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Influence of H2 reduction on lignin-based hard carbon performance in lithium ion batteries
Abstract
Lignin as a by-product of fuel alcohol industry is used to prepare hard carbon materials by acetone extraction, stabilization in N2 at 300 °C, carbonization in N2 and subsequent H2 reduction at 800 °C. The effect of H2 reduction after carbonization process on the performances of the prepared samples is systematically studied and a simple mechanism is proposed. Excitingly, it is demonstrated that the process of H2 reduction has a favorable influence on both structures and electrochemical performances of pyrolysis sample and an obvious improvement of capacity performance is obtained with reduction treatment. A first discharge/ charge capacity of 882.2/550.5 mA h g−1 (coulombic efficiency (CE) of 62.4%) is achieved at 0.1 C (1C = 372 mA g−1), and even after 200 cycles at 2 C a charge capacity of 228.8 mA h g−1 (about 92.8% retention ratio) remains and CE is above 99% during cycles for H2 reduced sample. The fabulous electrochemical performance could be attributed to high purity of acetone-extracted lignin, low surface oxygen-containing functional groups and relatively high graphitization degree of reduction sample. In a word, both the simple pyrolysis process and excellent electrochemical performance make lignin-based hard carbon a promising anode material for high-capacity and high-stability lithium ion batteries (LIBs).
... Additionally, acetone was used to extract lignin from a corn stalk lignin precursor; the extracted lignin was used to construct hard carbon materials through stabilization in nitrogen, carbonization in nitrogen, and hydrogen reduction [47]. Figure 5 shows the pyrolysis reaction mechanism that occurred after the lignin was extracted from a precursor with acetone. ...
... [46] Lithium battery anode material Acetone lignin from corn stalks 80% Stabilized at 300 • C for 2 h in N 2 in tube furnace. [47] Lithium battery anode material ...
... [48] Figure 5. Reaction mechanism using the pyrolysis technology. Reprinted from reference [47], with permission from Elsevier. ...
In recent decades, advancements in lignin application include the synthesis of polymers, dyes, adhesives and fertilizers. There has recently been a shift from perceiving lignin as a waste product to viewing lignin as a potential raw material for valuable products. More recently, considerable attention has been placed in sectors, like the medical, electrochemical, and polymer sectors, where lignin can be significantly valorized. Despite some technical challenges in lignin recovery and depolymerization, lignin is viewed as a promising material due to it being biocompatible, cheap, and abundant in nature. In the medical sector, lignins can be used as wound dressings, pharmaceuticals, and drug delivery materials. They can also be used for electrochemical energy materials and 3D printing lignin–plastic composite materials. This review covers the recent research progress in lignin valorization, specifically focusing on medical, electrochemical, and 3D printing applications. The technoeconomic assessment of lignin application is also discussed.
... For example, lignosulfonate has a large amount of sulfur content, which can be treated as a sulfur-doped agent in rechargeable batteries or supercapacitors [117][118][119][120][121][122] . Compared with lignosulfonate, alkali Table 1 Overview of lignin-derived anodes in lithium batteries [138][139][140][141][142][143][144][145][146] . ...
... It is, therefore, demonstrated that the multistage pore structures and graphitic structure of lignin-based carbon are favorable for the intercalation of lithium ions because of the fast diffusion of ions in the materials. Chang et al. investigated the influence of reduction environment on lignin-based hard carbon performance in LIBs [140] . As illustrated in Fig. 5 b, surface defects were created along with the polymerization of lignin monomers during the carbonization. ...
... (a) Schematic diagram of the formation process of lignin hierarchical porous carbon[138] , and (b) reaction mechanism during the pyrolysis process of lignin under H 2 environment[140] . Source: (a)[138] , Copyright 2015; (b)[140] , Copyright 2015. ...
Lignin, as a renewable bioresource, has been widely explored in cellulosic biofuel and several other industries. There are limited applications of lignin in the energy industry, especially in rechargeable batteries and supercapacitors, even though tremendous research work has been done regarding the use of lignin in these fields. It is vital to take lignin into consideration because its usage not only improves the performance of these devices but also reduces the cost, contributing to obtaining more sustainable and greener energy devices. This paper reviews recent developments of lignin-derived materials in rechargeable batteries and supercapacitors. It starts with a brief introduction of the benefits of lignin, followed by the fundamental nature and preparation of lignin-derived materials. Significant attention is paid to applications of lignin-derived materials in rechargeable batteries and supercapacitors including their use as binders and electrodes for rechargeable batteries, and electrodes and electrolytes for supercapacitors with a focus on the mechanisms behind their operation. The goal is to provide a detailed review of the critical aspects related to lignin utilized as an important resource for researchers working in a diverse range of fields dealing with energy storage and conversion. Lastly, a future vision on challenges and their possible solutions are presented.
... The larger interlayer distance of the samples compared to commercial graphite (0.335 nm) endows these materials with fast Li + diffusion, which is conducive to the improvement of rate capability. Notably, compared to the samples treated under argon, the H600 and H900 exhibit smaller d 002 due to reduced oxygen functional groups and edge defects (Table S3) [24]. The atomic ratio calculated based on XPS results shown in Table S5 also verified this tendency. ...
... As illustrated in Figure S3 and Table 1, the calculated R-values for A600, A900, H600, and H900 show the same trend as L c from XRD analyses. Taking the small variations in R and the larger L a of H600 and H900 compared to the samples treated under argon into consideration, it is deduced that H 2 reduction is more efficacious in improving the molecular structure along the a-axis than along the c-axis [24]. Raman spectroscopy was further conducted to distinguish and analyze the development of the graphitic structure. ...
Fast charging capability is highly desired for new generation lithium-ion batteries used in consumer-grade electronic devices and electric vehicles. However, currently used anodes suffer from sluggish ion kinetics due to limited interlayer distance. Herein, the coal-based semicoke was chosen as precursor to prepare cost-effective carbon anodes with high-rate performance through a facile pyrolytic strategy. The evolution of microstructure and its effect on electrochemical performance are entirely studied. The results show that large number of short-ordered defective structures are generated due to the occurrence of turbostatic-like structures when pyrolyzed at 900 °C, which are propitious to large interlayer distance and developed porous structure. High accessible surface area and large interlayer spacing with short-ordered defective domains endow the sample treated at 900 °C under argon (A900) with accelerated ion dynamics and enhanced ion adsorption dominated surface-induced capacitive processes. As a result, A900 delivers high capacity (331.1 mAh g−1 at 0.1 A g−1) and long life expectancy (94.8% after 1000 cycles at 1 A g−1) as well as good rate capability (153.2 mAh g−1 at 5 A g−1). This work opens a scalable avenue to fabricating cost-effective, high-rate, and long cycling life carbon anodes.
... [8] Through additional H 2 reduction treatment, our group prepared a lignin-based hard carbon for lithium ion batteries (LIBs), which exhibited an extreme boosting of initial coulombic efficiency compared with its pristine counterpart (ICE, from 42.4 % to 62.4 %) and capacity performances (e. g., from 138 mAh g À 1 to 222 mAh g À 1 after stably cycling at 2 C for 200 circles). [9] In view of poor Na-storage performances of the most commonly used graphite anodes in LIBs(although the capacity can be improved in ether-based electrolyte by staging Na-ion de-/intercalation to~150 mAh g À 1 compared to that of~30 mAh g À 1 in ester-based electrolyte), [10] researchers have also paid attention to the prospective application of lignin-based hard carbon in the resurgent SIBs, a very promising alternative source in particular for grid-scale energy storage. [11] For example, as early as in 2013, Mitlin et al. reported a hollow macroporous carbon derived from peat moss containing 80 wt% of hemicellulose and lignin, which delivered a stable capacity of 298 mAh g À 1 at 50 mA g À 1 (ca. ...
... One main reason is considered to be that the softening point of lignin (~210°C) is higher than its decomposition temperature (~200°C), which leads it very difficult to use pure lignin to prepare carbon with a particular morphology. [9] On the other hand, as indicated above, the natural cross-linked phenylpropane building-block structure of lignin also makes it difficult to form large-size graphite-like microcrystallite. Hence, successful preparation of hard carbon microspheres from low-cost lignin can be an important breakthrough in the development and commercialization of SIBs by removing its key anoderelated constraint. ...
We demonstrate a facile emulsion‐solvent evaporation process to easily convert lignin into a nanoporous N,P‐codoped hard carbon microsphere. The combined physiochemical characterizations indicate that this material possesses very suitable microstructure for electrochemical energy storage. The electrochemical measurements of sodium ion battery (SIB) show that, such lignin‐derived carbon microspheres also follow the widely‐accepted adsorption‐intercalation Na‐storage mechanism. The Na + diffusion coefficient in as‐obtained electrode could reach 10 –9 cm 2 s –1 . They exhibit quite excellent and balanced Na‐storage performances, such as large reversible and low‐voltage capacity (up to 307–336 and 229–246 mAh g −1 , respectively), high initial coulombic efficiency (78.7–82.4%), and good rate performance as well as long cycling stability (e.g., retaining at 248 mAh g –1 and a retention of ~92.2% after running at 0.1 A g –1 for 200 cycles). Consequently, this work not only provides a facile approach to realize high added‐value utilization of lignin, but also contributes to the development of eco‐environmental batteries using low‐cost materials.
... X-ray diffraction (XRD) and Raman analysis were further used to detect the microstructure of the as-prepared samples ( Fig. 2a and b). The XRD reflection peaks at ca., 22 and 44 represent (002) and (100) lattice plane of the graphite, respectively, indicating the formation of typical graphic-like structure [32,37]. With the increase of temperature, the peak position of (002) shifts from 21.56 to 22.34 , demonstrating a decrease in d-spacing from 0.412 nm to 0.397 nm, which might be associated with the decrease of the oxygen species and the increase of graphitization [38]. ...
... However, the efficiency of HC700 is lower than that of HC300 and HC400 as presented in Table S3, even though the amount of oxygen functional groups is the least for HC700. Similarly, the specific capacities of HC700 also show the same tendency that is different from the previous reports [32]. We ascribed this to the oxygen species and their evolution during H 2 reduction as above-mentioned. ...
... The electrodes produced from 50% PLA blends exhibited a high specific capacity of 611 mAh g −1 after 200 cycles at 186 mAh g −1 , owing to the increased porosity. In addition, the surface defect site and the degree of graphitization of LDC could be enhanced through H 2 reduction (Chang et al. 2015), in which the carbonyl content and interlayer spacing of LDC were improved via pre-oxidation process (Du et al. 2021). Thus, LDC as the anode in LIBs can obtain excellent rate ability and cycling stability through ingenious microstructure design. ...
Developing novel techniques to convert lignin into sustainable chemicals and functional materials is a critical route toward the high-value utilization of lignocellulosic biomass. Lignin-derived carbon materials hold great promise for applications in energy and chemical engineering, catalysis and environmental remediation. In this review, the state-of-art sciences and technologies for controllable synthesis of lignin-derived carbon materials are summarized, pore structure engineering, crystalline engineering, and morphology controlling methodologies are thoroughly outlined and critically discussed. Green chemical engineering with cost-effectiveness and precise carbonization tuning microstructure are future research trends of lignin-derived carbon materials. Future research directions that could be employed to advance lignin-derived carbon materials toward commercial applications are then proposed.
... The cathode material made up of 13 wt% carbon black, 76 wt% hydrolysis lignin, and 11 wt% polytetrafluoroethylene (PTFE)-based binder. Lithium batteries utilising hydrolysis lignin as an electrode materials has a discharge capacity of 450 mAhg − 1 [82]. Culebras et al [83,84] developed a piezoelectric material made of macro carbon nanotube yarns (CNTYs) treated to lignin from the gaseous state (23 wt %). ...
The pulp and biorefining industries produce their waste as lignin, which is one of the most abundant renewable resources. So far, lignin has been remained severely underutilized and generally burnt in a boiler as a low-value fuel. To demonstrate lignin's potential as a value-added product, we will review market opportunities for lignin related applications by utilizing the thermo-chemical/biological depolymerization strategies (with or without catalysts) and their comparative evaluation. The application of lignin and its derived aromatics in various sectors such as cement industry, bitumen modifier, energy materials, agriculture, nanocomposite, biomedical, H2 source, biosensor and bioimaging have been summarized. This comprehensive review article also highlights the technical, economic, environmental, and socio-economic variable that affect the market value of lignin-derived by-products. The review shows the importance of lignin, and its derived products are a platform for future bioeconomy and sustainability.
... The carbonization, a process of thermochemical decomposition of lignin/PMMA microspheres under nitrogen conditions, has been illustrated in Fig. 6a. When the temperature was in the range of room temperature to 200 C, the main changes for PMMA, lignin and lignin/PMMA microspheres were the removal of moisture [37,38]. In this stage, the weight loss of them was 0.2%, 4.3% and 4.4%, respectively, as displayed in Fig. 6b. ...
Despite the great advantages of interconnected porous architectures of three-dimensional carbon as functional materials, apparent common drawbacks restricting their widespread applications are high cost and non-renewable of the carbon precursors and complicated activation procedures. In this study, biomass-derived honeycomb-like multilayered carbon (HMC) is synthesized by electrospraying and direct carbonization for the first time. Poly(methyl methacrylate) (PMMA) is mixed with biomass-derived lignin, the only carbon source, to form lignin/PMMA microspheres and microbowls by electrospraying. One-step carbonization of prepared micromaterials to obtain ultralight HMC, and the microstructures and pore size of carbon materials are controllable by adjusting the applied voltage of electrospraying. The obtained HMC-13 by carbonization of lignin/PMMA microspheres possesses interconnected carbon skeleton, partially graphitized structure and hierarchical pore system composed of macropores, mesopores and micropores. Benefiting from the structural advantages, HMC-13 as electrode of supercapacitor delivers a high specific capacitance of 348 F g⁻¹ at 0.5 A g⁻¹ in aqueous electrolytes. Additionally, the supercapacitor exhibits excellent cycling stability with only 4% capacitance loss after 10 000 cycles. Based on these encouraging results, environmental friendliness and facile synthesis strategy, the biomass-derived ultralight porous carbon material holds great promise for facilitating wasted biomass utilization and developing sustainable energy products.
... Industrial lignin has the characteristics of high aromatic structure and high energy value, indicating that it has the potential to be transformed into phenolic platform chemicals (De Wild et al. 2009;Liu et al. 2016;Santana et al. 2018;Wang et al. 2019), biofuels (De Wild et al. 2009) and various functional materials (Zhou et al. 2007;Babeł and Jurewicz 2008;Chang et al. 2015;Xiong et al. 2017;Wang et al. 2018). However, industrial lignin has a wide variety of sources and complex structures, which seriously hinder high-value utilization. ...
Owing to its high aromaticity and carbon content , technical lignin as the by-product of chemical pulping and bio-refining industry can be converted into lignin-derived porous carbon (LPC) materials after activation, which is a promising strategy for high-value utilization. In particular, LPC with a higher surface area and graphitiza-tion will have a broad prospect as the electrode material for lithium-ion batteries (LIBs). However, the structure of technical lignin varies greatly due to its different industrial processes and botany sources, which remarkably affects the activation process and electrochemical properties of LPC. Herein, we study the effect of oxygen/carbon (O/C) ratio and molecular weight on the structure of LPC by exploring the effect of four kinds of technical lignin on K2CO3 activation. High O/C ratio can promote LPC to maintain a high specific surface area (SSA). High molecular weight and low O/C ratio were beneficial to increase the graphitization degree and keep the porous structure of LPC. The electrochemical performance evaluation showed that high graphitization and stable porous structure were beneficial for lithium-ion storage. Therefore, LPC from enzymatic hydrolysis lignin (EHL) had long cycle performance (490 mAh · g −1 at a current density of 400 mA · g −1) and excellent rate performance compared to lignin from chemical pulping.
... For example, hard carbon prepared from lignin achieved a first discharge capacity of 882.2 mA h g −1 at 0.1 C and remained at a charge capacity of 228.8 mA h g −1 (~92.8% retention ratio) after 200 cycles at 2 C. 176 Alkali lignin and its degradation products were carbonized to form graphenelike carbon sheet/Fe 3 O 4 nanocomposite anodes, which exhibited an ultra-high first discharge specific capacity of 3829 mA h g −1 at 50 mA g −1 . 81 In addition, it was reported that a binder-free Si/C anode exhibited a high specific capacity of 1557 mA h g −1 and was reversibly cycled at 0.54 A g −1 with 89.3% capacity retention over 100 cycles, which can be ascribed to the great role of the lignin-derived network in suppressing the volume change of Si nanoparticles during cycling. ...
Electrode and electrolyte materials with higher performance, longer life, and lower cost need to be developed, given the substantial growing demand for advanced electrochemical energy systems. Lignin, the second most abundant natural polymer, has been successfully demonstrated to be a viable precursor or feedstock for the preparation of high‐performance electrochemical energy materials and components such as electrodes, electrolyte additives, membrane separators, and binders. Moreover, techno‐economic analyses indicate that it is possible to prepare cost‐effective carbon structures from lignin at engineering scale, in contrast with current carbon products. These facts suggest that the scalable conversion of lignin into high‐value energy materials will offer a promising pathway to not only promote the utilization and valorization of lignin but also boost the development of advanced electrochemical energy systems. This review examines cutting‐edge renewable energy materials derived from various lignin compounds and their applications in electrochemical energy systems with an emphasis on supercapacitors, rechargeable batteries, and fuel cells. Meanwhile, this review also aims to carve out the critical barriers for lignin‐derived high‐performance materials for energy applications, and to identify viable approaches for the synthesis of sustainable new energy materials. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd
... Industry lignin can be obtained from a variety of low-cost woody plants and even from industrial waste such as pulping black liquor (mainly alkali lignin) and bio-refining residue (mainly enzymatic lignin). Lignin carbon material (LC) has been reported as lithium-ion anode materials [2,30,31]. Because lignin has less reactive functional groups and a certain degree of aromatic, the direct pyrolysis lignin carbon materials have poor surface functional properties, such as low specific surface area, low graphitization and non-porous structure. ...
As an abundant natural aromatic polymer with high carbon content, lignin can be regarded as an abundant carbon matrix precursor to develop cost-effective and environmental friendly porous carbon for energy storage materials. However, the porous lignin-derived carbon remains a great challenge as an anode for Li-ion batteries due to its low degree of graphitization. In this paper, a low-cost, productive and scalable industrial method has been adopted to fabricate highly graphitized lignin-based porous carbon (PLC-EHL-K2CO3) with K2CO3 activation using enzymatic hydrolysis lignin (EHL) as a raw material. PLC-EHL-K2CO3 was composed of multilevel lamellar structure possessing high specific surface area and macro- and mesoporous. Notably, the graphitization of PLC-EHL-K2CO3 was significantly improved compared with the common KOH activation. Meanwhile, the structure of lignin is an important factor affecting the structure of PLC, such as the molecular weight and oxygen functional groups. The high specific surface area, large pore volume and unique multilevel lamellar morphology bestow PLC an excellent lithium storage performance, and PLC-EHL-K2CO3 electrode displays a desirable reversible capacity of 520 mAh·g⁻¹ at a current density of 200 mA g⁻¹ over 200 cycles and increases 47.3% than PLC-EHL-KOH, and even at 1 A g⁻¹ a specific capacity of 260 mAh·g⁻¹ can be retained after 1000 cycles. This higher graphitization porous carbon material from low-cost renewable lignin is a good candidate for lithium storage equipment.
... Chang et al. examined the effect of H 2 reduction on the electrochemical performance of a ligninderived carbon anode. 24 At 74 mA g −1 , the anode demonstrated a capacity of ca. 400 mA h g −1 with an improved initial CE. ...
In this study, we demonstrate that lignin, which constitutes 30–40 wt% of the terrestrial lignocellulosic biomass and is produced from 2nd-generation biofuel plants as a cheap byproduct, is an excellent precursor material for sodium-ion battery anodes (NIBs). Because it is rich in aromatic monomers that are highly crosslinked by ether and condensed bonds, the lignin material carbonized at 1300 °C (C-1300) in this study has small graphitic domains with well-developed graphene layers, a large interlayer spacing (0.403 nm), and a high micropore surface area (207.5 m2 g-1). When tested as an anode in a NIB, C-1300 exhibited a high initial coulombic efficiency of 68% and a high reversible capacity of 297 mAh g-1 at 50 mA g-1 after 50 cycles. The high capacity of 199 mAh g 1 at less than 0.1 V with a flat voltage profile and extremely low charge/discharge voltage hysteresis (< 0.03 V) make C-1300 a promising energy dense electrode material. In addition, C-1300 exhibited an excellent high-rate performance of 116 mAh g-1 at 2.5 A g-1 and showed stable cycling retention (0.2% capacity decay per cycle after 500 cycles). By comparing the properties of the lignin-derived carbon with oak-sawdust-derived and sugar-derived carbons and a low-temperature carbonized sample (900 °C), the reasons for the excellent performance of C-1300 were determined to result from facilitated Na+ ion transport to the rich in microporous regions that penetrate through the less-defective and enlarged interlayer spacings.
... So most lignin need to undergo pretreatment to change thermal properties or be blended with other thermoplastic polymers to increase its plasticity performance before forming process [5,6]. The research on lignin based carbon materials started fifty years ago, and several methods, physical and chemical treatment, had been described to synthesize activated carbons and carbon fiber used in adsorption [7], lithium ion battery [8] or supercapacitor [9] from commercial lignins. Especially lignin based carbon fiber had been prepared by melting spinning, dry spinning [10] or wet spinning successfully [11]. ...
The review presents a survey of the literature on structure–property relationships in epoxy-clay nanocomposites. Herein, various pivotal parameters affecting structures and properties of the nanocomposites including various types of modification as well as a vast range of available dispersion techniques were discussed. Opportunities and challenges in regards to potential applications of nanoclay in multi-scale composites have been also addressed. The multi-scale composites containing nanoclays have been reviewed in terms of mechanical properties in both out-of-plane and in-plane directions, and compared with those containing carbon based nanofillers. In this regards, the improving mechanisms in mechanical properties of both epoxy-clay nanocomposites and nanoclay filled fiber reinforced composites were also discussed.
... The performance of this binder-free and conductive additive free electrode is comparable to electrodes where conventional binders or polymer binders were used. 9,39,50,56,57 Although lignin has been previously explored for use in sodium-ion batteries and carbon fibers as active material/support for lithium-ion batteries, 28,58,59 this work demonstrates it effectiveness in silicon-based negative electrodes. ...
This work demonstrates a high performance and durable silicon nanoparticle based negative electrode in which conventional polymer binder and carbon black additive are replaced with lignin. The mixture of silicon nanoparticles and lignin, a low cost, renewable, and widely available biopolymer, was coated on copper substrate using the conventional slurry mixing and coating method and subsequently heat treated to form the composite electrode. The composite electrode showed excellent electrochemical performance with an initial discharge capacity of up to 3086 mAh g-1 and retaining 2378 mAh g-1 after 100 cycles at 1A g-1. Even at relatively high areal loading of ~1 mg cm-2, an areal capacity of ~2 mAh cm-2 was achieved. The composite electrode also displayed excellent rate capability and performance in a full-cell setup. Through synergistic analysis of X-ray photoelectron spectroscopy (XPS), Raman, and nano-indentation experiment results, we attribute the amazing properties of Si/lignin electrodes to the judicious choice of heat treatment temperature at 600°C. At this temperature lignin undergoes complex compositional change during which a balance between development of conductivity and retaining of polymer flexibility is realized. We hope this work could lead to practicable silicon based negative electrodes and stimulate the interest in the utilization of bio-renewable resources in advanced energy applications.
... The curves for the PF-CNFs are similar to the results for materials with sodium ion binding with hydrogen-terminated graphene sheets or insertion between the graphene sheets [9,10,53,54]. Notably, additional plateau in PF-800, a common phenomenon in lignin-derived precursors [55,56], may attribute to SEI formation. We may attribute the high-voltage sloping to insertion between graphite layers, while the low-voltage storage behavior is attributed to insertion into nanopores. ...
... It can be seen from Table 1 that V micro /V total decreases from 67 FT-IR spectra in Fig. 3a are also applied to evaluate the functional groups in LACs. After activation at 800°C, LACs show almost identical spectra: besides OH stretching peak around 3435 cm −1 , only peaks of 1627, 1380/1044, and 1086 cm −1 remain, indicative of the aromatic skeletal vibrations, C-H deformations, and C-O-C vibrations, respectively [26,27]. It has also been reported that the C-O-type groups with high stability are probably beneficial to tailor the surface chemistry of ACs to have an enhanced and stable capacitance [9]. ...
Lignin as the second most abundant natural polymer was applied to prepare a hierarchical porous carbon (HPC) for supercapacitors (SCs). Direct activation with various KOH dosages was applied to obtain HPC. Both pore size distribution and electrochemical performance were evaluated and compared to optimize the KOH dosages. Field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), Fourier transform infrared spectrometry (FT-IR), and Raman spectroscopy were also applied to better understand the structure change of HPC with KOH dosages. High gravimetric capacities (C
g) of 268 and 162 F g−1 were obtained in aqueous and organic solutions, respectively. Excellent rate and cycle performance demonstrated the stable structure of HPC. Energy density could reach as high as 40.89 W h kg−1 in organic solution. Besides, it was also concluded that a high C
g can be obtained with low KOH dosage in aqueous solution while high KOH dosage was needed in organic solution. In a word, lignin was indeed a suitable precursor for the preparation of HPC in SCs.
Hard carbon (HC) anode shows great potential due to its high capacity and excellent rate performance. However, state-of-the-art HC anode still suffers insufficient initial Coulomb efficiency (ICE) due to the abundant Li-trapping sites. Herein, we demonstrate a facile annealing engineering for HC anodes to improve the ICE and the mechanism is systematically studied. Accordingly, during the annealing process, metastable O- and N-containing functional groups are pyrolyzed, which cause the microstructure reconstruction of HC. Therefore, irreversible lithium ions adsorption is reduced significantly and the conversion of sp3 to sp2 C contributes to the localized graphitization of HC. Consequently, the optimized HC achieves ultra-high ICE of 90% from initial 61%. It is demonstrated that HC will adsorb H2O and some organic species from environment gradually, causing conversion of some electrochemical stable functional groups to the irreversible Li-trapping sites. This work provides facile strategy and novel insight for high ICE HC anodes.
Biopolymers functionalization is perceived as an innovative approach to revolutionizing bio-catalyzed chemical transformations. Lignin, the chief natural source of polyphenols, has an aromatic structure with plenty of beneficial chemical groups. Accordingly, lignin can be functionalized, copolymerized, or recombined with different types of chemicals to produce highly efficient catalysts. Moreover, the stability and biodegradability of lignin make it an efficient bio-immobilizer for diverse metals (Pt, Pd, Ag, Cu, Fe, etc.), which are known for their excellent catalytic performances. In addition, the solid nature of the lignin-derived catalyst has excellent advantages in terms of simple catalyst recovery and reuse over consecutive cycles with high stability. The present work compiles the newly adopted approaches to valorize lignin in the field of catalysis. Lignin-derived acid and base catalysts, lignin metal-free catalysts, and lignin-supported metal catalysts have demonstrated the full potential of lignin in hydrolysis, esterification, oxidation, condensation, hydration, and multicomponent reactions. The synthesis methods, properties, and catalytic capacity of lignin-based catalysts were assessed and contrasted with conventional catalysts. Attractively, the inclusion of lignin in catalysis appeared as a novel upgrading strategy that offers eco-friendly and profitable materials, leading to simple and green chemical synthesis, as well as a revolutionary shift in the industrialization of biomass-derived materials generally, and functionalized lignin-based catalysts specifically.
Feedstock design is crucial for lignocellulosic biomass use. Current strategies for feedstock design cannot be readily applied to improve the quality of biomass-based materials, limiting the sustainability and economics of lignocellulosic biorefineries. Recent studies have advanced the understanding of biomass structure–property relationships and discovered several characteristics, such as molecular weight, uniformity, linkage profile, and functional groups, that are critical for manufacturing diverse quality biomaterials. These discoveries call for fundamentally different strategies for feedstock development. Such strategies need to rediscover the roles of monolignol biosynthesis enzymes and leverage lignin polymerization enzymes to achieve precise control of lignin molecular structure. These innovations could transform biomass into feedstock for high-quality biomaterials, addressing essential environmental challenges and empowering the bioeconomy.
Hard carbons are widely investigated as potential anodes for lithium and sodium ion batteries owing to their internally well-tailored textures (closed pores and defects) and large microcrystalline interlayer spacing. The renewable biomass is a green and economically attractive carbon source to produce hard carbons. However, the chemical and structural complexity of biomass has plagued the understanding of evolution mechanism from organic precursors to hard carbons and the structure–property relationship. This makes it difficult to finely tune the microstructure of biomass-derived hard carbons, thus greatly restricting their high-performance applications. Most recently, the optimal utilization and controllable conversion of biomass-derived polymeric materials (such as starch, cellulose and lignin) at the molecular level have become a burgeoning area of research to develop hard carbons for advanced batteries. Considering the principal source of carbonaceous materials is from biomass pyrolysis, we firstly overview the chemical structures and pyrolysis behaviors of three main biopolymers. Then, the controllable preparation of hard carbons using various physicochemical properties of biopolymers at the molecular level is systematically discussed. Furthermore, we highlight present challenges and further opportunities in this field. The Review will guide future research works on the design of sustainable hard carbons and the optimization of battery performance.
Carbon-based materials have emerged as promising anode candidates for lithium-ion capacitors (LICs) owing to the advantages of high electronic conductivity and environmental benignity. However, further development of carbonaceous anodes has been greatly hindered by the sluggish kinetics and insufficient cycling stability. Herein, mesopore-rich N-doped carbon nanofibers (MNCNF) membranes are designed as a free-standing anode material to achieve ultra-high rate and ultra-long lifespan Li storage performance. The interconnected network with rich mesopore volume, high doping level of pyridinic/pyrrolic N, and expanded interlayer spacing affords the as-fabricated MNCNF anode abundant active sites, promoted electronic conductivity and superior diffusion kinetics. With prominent merits of pore and defect engineering, MNCNF anode manifests extraordinary Li storage performance in terms of ultra-high rate capability (139 mA h g⁻¹ at 50 A g⁻¹) and ultra-long cycling stability (370 mA h g⁻¹ after 10000 cycles at 10 A g⁻¹). More importantly, LICs by using MNCNF as anodes deliver a high energy density of 165 Wh kg⁻¹ and an ultra-high power density of 132 kW kg⁻¹, together with a high capacitance retention of 84% after 20000 cycles. This study demonstrates the combination of pore and defect engineering for boosting Li storage performance and holds great promise for practical applications.
Carbonaceous materials have been accepted as a promising family of anode materials for lithium‐ion batteries (LIBs) owing to optimal overall performance. Among various emerging carbonaceous anode materials, hard carbons have recently gained significant attention for high‐energy LIBs. The most attractive features of hard carbons are the enriched microcrystalline structure, which not only benefits the uptake of more Li+ ions but also facilitates the Li+ ions intercalation and deintercalation. However, the booming application of hard carbons is significantly slowed by the low initial Coulombic efficiency, large initial irreversible capacity, and voltage hysteresis. Many efforts have been devoted to address these challenges toward practical applications. This paper focuses on an up‐to‐date overview of hard carbons, with an emphasis on the lithium storage fundamentals and material classification of hard carbons as well as present challenges and potential solutions. The future prospects and perspectives on hard carbons to enable practical application in next‐generation batteries are also highlighted. Hard carbons with high reversible capacity, excellent rate capacity, superior cycling stability, and low working potential, are better positioned to be chosen as the next‐generation advanced anode materials compared to soft carbons and graphite. Herein a comprehensive analysis of classification, formation, microstructure, and lithium storage fundamentals of hard carbons is provided, which is expected to be very attractive for the energy material communities.
Lignin, an aromatic polymer, offers interesting electroactive redox properties and abundant active functional groups. Due to its quinone functionality, it fulfils the requirement of erratic electrical energy storage by only providing adequate charge density. Research on the use of lignin as a renewable material in energy storage applications has been published in the form of reviews and scientific articles. Lignin has been used as a binder, polymer electrolyte and an electrode material,i.e.organic composite electrodes/hybrid lignin-polymer combination in different battery systems depending on the principal charge of quinone and hydroquinone. Furthermore, lignin-derived carbons have gained much popularity. The aim of this review is to depict the meticulous follow-ups of the vital challenges and progress linked to lignin usage in different lithium-based conventional and next-generation batteries as a valuable, ecological and low-cost material. The key factor of this new finding is to open a new path towards sustainable and renewable future lithium-based batteries for practical/industrial applications.
In this study, a simple and effective pre-lithiation strategy is developed to resolve a large initial irreversible capacity loss and low initial Coulombic efficiency of porous carbon as anode material for Li-ion batteries. By using this strategy, Li-incorporated hierarchically porous carbon monoliths (PCMs) are successfully obtained from water-soluble carboxymethyl cellulose lithium salt. The prepared PCMs are found to have amorphous carbon structures and well-developed hierarchical pore architectures. In addition, Li is found to be homogeneously incorporated throughout the prepared PCMs. The electrochemical properties of the prepared Li-incorporated PCMs are studied in a half-cell configuration and exhibit lower initial irreversible capacity along with stable cycle life at high current densities. Generally, the resistance of LIB cell remarkably increases at the end of discharge. Here, the galvanostatic intermittent titration technique analyses reveal a higher diffusion coefficient of the prepared Li-incorporated PCMs, specifically at the end of discharge. Therefore, this inherent property of Li-incorporated PCMs is favorable for high-power LIB anode materials.
As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.
Lignin-derived hard carbon (HC) has great potential as energy storage materials. However, it is difficult to obtain desired electrochemical performances by direct carbonization of lignin. Herein, we demonstrate a pre-oxidation strategy to enhance the reversible capacity of hard carbon with lignin as precursor. The pre-oxidation mechanism and its influence on the microstructures of the resulted hard carbon are systematically studied. Based on in-situ FT-IR and ¹³C NMR spectrum, etc., it is confirmed that three dominant configurations of oxygen-containing functional groups are formed during the process, and the content of the desired carbonyl groups (C=O) reaches a maximum value at a pre-oxidation temperature of 200 oC. Meanwhile, the alkyl groups are transformed into peroxides or alcohols, contributing to intermolecular cross-linkage within lignin. As a result, the obtained material with highly random orientation nanotexture gives a much larger d002 and abundant porous structure. Benefiting from these structural merits, the optimized lignin-derived hard carbon enables excellent Li-ion storage performance with a reversible capacity of 584 mAh g⁻¹ at 50 mA g⁻¹. This work provides insights into the rational design of high-performance hard carbon anodes for Li-ion batteries and beyond.
The comprehensive utilization of Si-rich biomass is restrained by macromolecular lignin and a large amount of ash. In this study, rice husks (RHs) are treated as a representative by alkali extraction and acid precipitation, and the obtained lignin-SiO2 composite is modified by carbonazation, ball milling, magnesiothermic reduction and additives. Through these processes, a Si/C composite with excellent electrochemical properties is obtained and performs stable cycling performance with high specific capacity retention of 572 mA h g⁻¹ at 1 A g⁻¹ after 1000 cycles. This introduced method provides a potential for utilizing Si-rich biomass comprehensively and preparing desirable Si/C anode materials from Si-rich biomass derived lignin-SiO2 composites.
Hard carbon (HC) is recognized as a promising anode material with outstanding electrochemical performance for alkali metal‐ion batteries including lithium‐ion batteries (LIBs), as well as their analogs sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs). Herein, a comprehensive review of the recent research is presented to interpret the challenges and opportunities for the applications of HC anodes. The ion storage mechanisms, materials design, and electrolyte optimizations for alkali metal‐ion batteries are illustrated in‐depth. HC is particularly promising as an anode material for SIBs. The solid‐electrolyte interphase, initial Coulombic efficiency, safety concerns, and all‐climate performances, which are vital for practical applications, are comprehensively discussed. Furthermore, commercial prototypes of SIBs based on HC anodes are extensively elaborated. The remaining challenges and research perspectives are provided, aiming to shed light on future research and early commercialization of HC‐based SIBs.
Lithium-ion capacitor (LIC) bridging gap between lithium ion battery and electrochemical capacitor has attracted myriad interests. Lignin, the second most abundant natural polymer, is also the main by-products treated as a waste in pulp and paper industry, which causes severe pollution to the aerosphere, water and soil. Herein, for the purpose of constructing high performance LIC and high value utilization of biomass waste, by regulating the porous framework and graphitic degree, lignin is converted to two kinds of functional carbons that serve as the electrode materials in LIC. Lignin-derived hierarchical porous carbon (LPC-3) prepared via the combination of freeze drying and activation displays a large specific surface area of 2490 m2 g-1 and a high fraction (54%) of pores in size more than 1.25 nm. As a result, a high specific capacitance of 145 F g-1 and a superior cyclic stability of 87% retention after 5000 cycles at 1 A g-1 are recieved. Simultaneously, lignin-derived graphitic carbon (LGC-1500) synthesized with the aid of catalyst (Fe) exhibits high plateau capacity (182 mA h g-1 below 0.2 V) and superior rate capability (131 mA h g-1 at 5 A g-1) thanks to that high fraction of extended graphitic structure is embedded in amorphous structure. Additionally, with optimization, the assembled LGC-1500//LPC-3 LIC delivers a high energy density of 97 Wh kg-1, a high power density of 11.4 kW kg-1 and a superior cyclic stability of 92.3% retention after 5000 cycles at 1 A g-1. This strategy realizes the high value utilization of lignin and provides insights into the design of high performance LICs and other energy storage systems.
Nitrogen-doped lignin-based carbon microspheres are synthesized using 3-aminophenol as a nitrogen source by the hydrothermal method. The structural change and the effect on the electrochemical properties are systematically investigated.
Nitrogen-doped lignin-based carbon microspheres represent well-developed spherical morphology with many active sites, ultramicroporous (<0.7 nm) structure, and large interlayer spacing. Consistent with the obtained physical structures and properties, the nitrogen-doped carbon microspheres exhibited fast sodium ion adsorption/intercalation kinetic process and excellent electrochemical performance. For example, a reversible specific capacity of 374 mAh g⁻¹ at 25 mA g⁻¹ with high initial coulombic efficiency of 85% and high capacitance retention of 90% after 300 cycles at 100 mA g⁻¹ and stable charge/discharge behavior at different current density is obtained. The additional defects and abundant ultramicroporous structure can enhance slope capacity, and large interlayer spacing is considered to be the reason for improving plateau capacity.
Recently, sodium-ion batteries have been intensively studied as an alternative to lithium-ion batteries because of the abundance of sodium and its ability, for example, to answer to smart grid energy storage applications. Among all anode materials, carbonaceous materials have shown promising results, particularly hard carbons owing to their high capacity and low insertion voltage (vs. Na⁺/Na). However, these materials often suffer from their high cost and low initial coulombic efficiency. In this paper, we investigate an easy route of hard carbon synthesis from low-cost pitch precursor. A pretreatment under a controlled atmosphere can hinder the graphitization of the pitch upon pyrolysis and induce an amorphous-like microstructure with high Na storage capacity. We also investigate the mechanism of pre-oxidation and show the importance of parameters optimization such as the atmosphere and the duration. A hard carbon with impressive electrochemical performances was obtained from a 12-hour pre-treatment at 300°C under oxygen flow followed up by a 2-hour carbonization at 1400°C under nitrogen with a high yield of 49%. This material delivers remarkable 312 mAh.g-1 of reversible capacity at C/20 for only 10 % of irreversibility at the first cycle. This work emphasizes the potential of pitch-based hard carbons for further industrialization of sodium-ion batteries.
Here, we report a nano-sized red phosphorous/biomass-derived porous carbon ([email protected]) which is employed as anode materials for lithium ion batteries (LIBs) via a facile vaporization−condensation−conversion strategy (VCC) with tobacco stem as the carbon precursor. The biomass-derived porous carbon not only acts as the host of red phosphorus to enhance the electrical conductivity, but also minimizes the volume expansion (≈400%) during cycling. The obtained [email protected] composite with a high red phosphorus content (62.1 wt%) delivers a high specific capacity of 1689 mA h g⁻¹ at 500 mA g⁻¹ with an initial Coulombic efficiency (ICE) of 91.7% and superior rate capability of 599 mA h g⁻¹ at 30 A g⁻¹. Furthermore, a high reversible capacity of 918 mA h g⁻¹ can be retained over 600 cycles at 5 A g⁻¹, indicating a remarkable cycle stability. More importantly, the introduction of agriculture waste-tobacco stem contributes to building low-cost, high-performance anode materials.
Coal tar pitch (CTP) with high carbon content and wide source of raw materials was an excellent precursor for the preparation of porous carbons (PCs). CTP was composed of polycyclic aromatic hydrocarbons (PAHs) with complex molecular size and chemical structure, the separation of CTP into several fractions with relatively narrow molecular weight by solvent extraction was of significance for CTP utilization. In this paper, CTP was treated by single-solvent extraction (carbon disulfide, acetone and ethyl acetate), and the six fractions were used as raw materials to prepare PCs as electrode material for electric double layer capacitor. The fractions were well characterized and the effect of mass distribution of different narrow fractions on structure property and electrochemical performance of the PCs was studied. The PCs prepared by carbon disulfide extract, acetone raffinate and ethyl acetate extract, containing more PAHs, exhibited the excellent specific capacitance performance in comparison with its residual components. The remarkable performance might contribute in the enhanced transport of electrolyte ions via the molecular graphene structure of PAHs. Additionally, the PC prepared by carbon disulfide raffinate showed outstanding cycling performance (99.7% at 2 A g-1 after 15,000 cycles) which was related to its unique layered porous structure.
Highly acidic lignin-derived sulfonated carbons (LDSCs) were produced from hardwood and softwood kraft lignins under mild conditions by applying fractionation and/or pre-carbonization treatments combined with acid-assisted hydrothermal carbonization. The use of lignin fraction with higher amount oxygen, obtained from the fractionation process, resulted in carbon with the highest density of surface acid groups and improved catalytic activity. The LDSCs were successful tested in the dehydration reaction of fructose to obtain 5-hydroxymethylfurfural, and the best catalyst can be recycled without loss in its catalytic activity after perform a simple regeneration process. In contrast, the pre-carbonization step, commonly performed in several works, resulted in LDSCs with low acidity. A simple and optimized methodology for obtaining LDSCs under mild conditions was developed, and the correlations between the preparation method and the physicochemical and catalytic properties established in this work may be extendible to other starting materials for rational sulfonated carbons production.
Sodium ion batteries are expected to be an alternative of lithium ion batteries because of the inexpensive raw materials. However, the anode materials still face the problems of low capacity and initial Coulomb efficiency, even for the hard carbons which are expected to commercial application. Here, we report a resin nanosphere derived from lignin through double solvent evaporation and resinification. Benefiting from the phenol‐formaldehyde condensation to form linear polymers, the samples possess a large microcrystalline size, moderate interlayer distance and defects sites in the turbostratic structure, which enhance the sodium storage capacity. The carbonized lignin‐based resin spheres (CLRSs) exhibit promising electrochemical performance with a comparable reversible capacity of 347 mAh g−1 and high ICE of 74%. Furthermore, the sodium storage mechanism into the obtained samples was also investigated by analyzing the relationship between the structure optimization and electrochemical performance. This article is protected by copyright. All rights reserved.
Lignin carbon fibres are cheaper than carbon fibres from petroleum sources, but they are yet to meet the required performance for automotive applications. They supersede petroleum-based carbon fibres in terms of cost, lightweight, environmentally sust ainability, availability and renewability. It is evident that the performance of lignin carbon fibres depends on their sources (e.g. biomass type) and processing/treatments. To enhance the application of these fibres, there is need for in-depth understanding of the evolution of their properties considering their sources, extraction methods, and further processings. On the other hand, it is important to understand the driving factors in the economic efficiency of the carbon fibres. This will guide researchers and industrialists in the search for high performance lignin carbon fibres with acceptable economic efficiency.
Hard carbon draws great interests as anode material in lithium ion batteries (LIBs) due to its high theoretical capacity, high rate capability and abundance of its precursors. Herein we firstly synthesize the lignin-melamine resins by grafting melamine onto lignin. Afterwards, nitrogen doped hard carbon is prepared by the pyrolysis of lignin-melamine resins with the aid of catalyst (Ni(NO3)2·6H2O) at 1000 °C. Compared with the samples without nitrogen-doping and catalysis, as-prepared nitrogen doped hard carbon exhibits higher reversible capacity (345 mAh g⁻¹ at 0.1 A g⁻¹), higher rate capability (145 mAh g⁻¹ at 5 A g⁻¹) and excellent cycling stability. The superior electrochemical performance is ascribed to the synergistic effect of nitrogen doping, graphitic structure and amorphous structure. Among them, nitrogen doping could create the vacancies around the nitrogen sites, which enhance the reactivity and the electronic conductivity of materials. Additionally, graphitic structure also enhances the electronic conductivity of materials, thus improving the electrochemical performance of hard carbon. It is worthwhile that lignin, renewable and abundant biopolymer, is converted to hard carbon with good electrochemical performance, which realizes the high value utilization of lignin.
Commercial lignin, by-product of enzymatic hydrolysis of biomass for bioethanol production, was used to prepare lignin based microsphere by reverse phase polymerization. The reverse phase polymerization had favorable influence on the morphology, size distribution and thermal stability by coordinating solid content and dispersed phase content of lignin emulsion. The carbonization yield at 870 degrees C of lignin based microsphere reaches to 38.87% by improving 5% from lignin precursor 33.43%, at solid content 0.059 and dispersed phase content 0.050. The mechanism is postulated based on the results from elemental analysis, FT-IR spectroscopy and thermogravimetric analysis. Furthermore, the lignin based microsphere could directly carbonize without pre-oxidization process. Hence, the reverse phase polymerization is a meaningful and possible industrial process. And the gravimetric capacitance of lignin based activated carbon microsphere (LAC-M) is as high as 334 F g(-1), and even after 10,000 cycles at 1 A g(-1) a specific capacity of 286 F g(-1) remains. Thus, LAC-M is a promising material for high performance SCs. (C) 2017 Published by Elsevier B.V.
Different structured activated carbons (ACs) were made from lignin (alkaline) by one-step activation. Using ZnCl2, KOH and K2CO3 as activating agents and the effect of activating agents on the electrochemical properties of the ACs for electric double layer capacitor (EDLC). The ACs prepared by the three kinds of activating agents are mainly microporous, while the ZnCl2-activated and KOH-activated ACs contain mesoporous through the nitrogen adsorption-desorption test. All the ACs used as electrode for EDLC showed excellent cyclability. The small amount of CO2 produced by K2CO3 decomposition involved in the activation reaction and a series of reactions between carbon of lignin and K2CO3, giving a AC with the maximum specific surface area of 1585 m² g⁻¹, and the best specific capacitance (Cs) performance of 263.46 F g⁻¹ at the current density 40 mA g⁻¹, using a two-electrode system. The results indicate that the K2CO3 as activating agent to prepared lignin-based AC applied in EDLC is appropriate.
Alkaline lignin extracted from oak wood cooperage wastes was chemically modified to prepare beads by suspension polymerization on water without the use of organic solvents. These beads were macroporous and swelled in hydrophilic solvents. They were functionalized under microwaves to be used as scavenging agents in winery applications. The beads prepared by this approach have the advantage of being more acceptable by winemakers than synthetic polymer supports previously reported. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013
The reversible Li+ storage sites and storage–de-storage mechanisms are studied with the carbonaceous materials prepared from methylnaphthalene-derived isotropic pitches. Results of the electrochemical studies indicate that these carbons have at least three different Li+ storage sites: Li+ ions are de-stored from site I at 0.0–0.12 V (vs. Li/Li+), from site II at 0.12–0.8 V, and from site III at >0.8 V. Site III is the most prosperous among the three when the preparation temperature is <700°C. The number of site I, which is negligible at <700°C, steadily grows at the expense of site III to reach a maximum population at 1000–1200°C and diminishes thereafter. Site I looks similar to site III in that its discharge potential profile appears as a plateau, but differs in that it shows a negligible hysteresis between the charging and discharging potential. A large potential hysteresis is observed with site III. Site III is likely to be the void spaces where some amount of hetero-atoms (H and O) or dangling bonds still exist, whereas site I is another type of void that is converted from site III by ‘molecular bridging’ between the randomly oriented stacks of small constituent molecules. During the charging reaction, Li+ ions are stored at site II first, then at sites I and III in order. But Li+ de-storage takes place from site I first, then sites II and III.
Background
Lignin is one of the three major components in plant cell walls, and it can be isolated (dissolved) from the cell wall in pretreatment or chemical pulping. However, there is a lack of high-value applications for lignin, and the commonest proposal for lignin is power and steam generation through combustion. Organosolv ethanol process is one of the effective pretreatment methods for woody biomass for cellulosic ethanol production, and kraft process is a dominant chemical pulping method in paper industry. In the present research, the lignins from organosolv pretreatment and kraft pulping were evaluated to replace polyol for producing rigid polyurethane foams (RPFs).
Results
Petroleum-based polyol was replaced with hardwood ethanol organosolv lignin (HEL) or hardwood kraft lignin (HKL) from 25% to 70% (molar percentage) in preparing rigid polyurethane foam. The prepared foams contained 12-36% (w/w) HEL or 9-28% (w/w) HKL. The density, compressive strength, and cellular structure of the prepared foams were investigated and compared. Chain extenders were used to improve the properties of the RPFs.
Conclusions
It was found that lignin was chemically crosslinked not just physically trapped in the rigid polyurethane foams. The lignin-containing foams had comparable structure and strength up to 25-30% (w/w) HEL or 19-23% (w/w) HKL addition. The results indicated that HEL performed much better in RPFs and could replace more polyol at the same strength than HKL because the former had a better miscibility with the polyol than the latter. Chain extender such as butanediol could improve the strength of lignin-containing RPFs.
Production of ethanol by bioconversion of lignocellulosic biomass has attracted much interest in recent years. However, the pretreatment process for increasing the enzymatic digestibility of cellulose has become a key step in commercialized production of cellulosic ethanol. During the last decades, many pretreatment processes have been developed for decreasing the biomass recalcitrance, but only a few of them seem to be promising. From the point of view for integrated utilization of lignocellulosic biomass, organosolv pretreatment provides a pathway for biorefining of biomass. This review presents the progress of organosolv pretreatment of lignocellulosic biomass in recent decades, especially on alcohol, organic acid, organic peracid and acetone pretreatments, and corresponding action mechanisms. Evaluation and prospect of organosolv pretreatment were performed. Finally, some recommendations for future investigation of this pretreatment method were given.
Non-graphitizable carbon (hard carbon) as a negative electrode material for lithium-ion batteries is investigated by X-ray photoelectron spectroscopy, and hard X-ray photoelectron spectroscopy (HX-PES). HX-PES spectra have peaks of both the solid electrolyte interphase on the hard carbon surface and the hard carbon itself. The change in spectrum with state of charge is observed by HX-PES. Hard carbon has two types of lithium insertion site; between graphene sheets and into nano-scale voids. These spectroscopic results are consistent with the lithium insertion mechanism into hard carbon.
We have prepared carbon anode materials by pyrolysis of rice husk (RH). Through X-ray powder diffraction, Brunauer-Emmett-Teller (BET) measurement, and ICP-AES analysis, the effects of acid-base pre-treatment, pyrolysis temperature, and the use of a proprietary poregenic agent on the cell capacity of these materials were investigated. The carbonaceous materials made from RH treated with a proprietary agent showed an extraordinarily high reversible capacity of 1055 mAh/g. To our best knowledge, this new hard carbon material possesses the highest reversible capacity ever reported for any carbon anode materials of lithium-ion batteries.
Low-cost and bio-based carbon nanofibrous webs (PL-CNFs) are fabricated from polyacrylonitrile (PAN) - refined lignin (RL) which is extracted from hardwood lignosulfonate via simple eletrospinning followed by stabilization and carbonization. The effects of the PAN/RL mass ratios varying from 9/1,7/3 to 5/5 and heat-treatment temperatures (HTTs) in the range from 800, 1000 to 1300 °C on morphology and structure of PL-CNFs are systematically studied. Due to unique morphology and weakly ordered turbostratic microstructure of the 3-D conductive composite networks, the PL-CNFs anode obtained at 1300 °C with a mass ratio of 5/5 exhibits a high reversible capacity of 292.6 mA h g-1 with an initial efficiency of 70.5% at a constant current density of 0.02 A g-1 when used as free-standing and binder-free anodes for sodium ion batteries (SIBs). The anode also presents high rate capability (210 and 80 mA h g-1 at 0.4 and 1 A g-1, respectively) and excellent cycle stability (247 mA h g-1 reversible capacity with 90.2% capacity retention ratio at 0.1 A g-1 over 200 cycles). It is demonstrated that biomass waste lignin can be applied as a promising precursor to fabricate low-cost-high performance carbon electrode materials for SIBs.
Carbonaceous materials pyrolyzed from green tea leaves are fabricated and characterized for their potential application as high-performance anodes in lithium ion batteries (LIBs). Three different pyrolysis temperatures (700, 800, and 900 °C) are employed, and the most efficient pyrolysis temperature is determined through a variety of physical and electrochemical measurements. The carbon pyrolyzed at a relatively low temperature of 700 °C contains numerous functional groups, defects that are different from those in graphitic carbon, and large pores. Consequently, the sample exhibited a relatively large capacity of 471 mAh g-1 at the 50th cycle, even though high initial irreversibility was observed. Furthermore, when compared to the extremely low capacity of graphite (12.7 mAh g-1), the carbon specimen pyrolyzed at 700 °C displays an excellent high-rate capability of 131 mAh g-1 at 10 C. Such a result is attributed to the relatively isotropic structures and large-size pores in the sample, which facilitates the rapid diffusion of lithium ions.
A novel biomass-based nitrogen-doped free-standing fused carbon fibrous mat was fabricated from lignin-polyethylene oxide (PEO) (90:10) blend via electrospinning followed by carbonization and thermal annealing in the presence of urea. The morphology and structure of the carbon fibers were characterized by field-emission scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and elemental analysis, and their electrochemical properties were investigated for the first time as anode in lithium ion batteries (LIBs). The fused carbon fibers without nitrogen doping exhibited high specific capacity up to 445 mAh g(-1) at a current density of 30 mA g(-1) (comparable to polyacrylonitrile (PAN)-derived carbon nanofibers) and good cyclic stability at different current rates. After thermal annealing in the presence of urea, the charge capacity was further improved to as high as 576 mAh g(-1) and still maintained a good capacity of about 200 mAh g(-1) even at a high current rate of 2000 mA g(-1). This research demonstrates the great promise of lignin-derived nanocarbon materials for applications in energy storage systems.
Low-cost carbon nanofibers are fabricated from lignin, the second most abundant raw material in wood after cellulose and polyacrylonitrile mixture as a carbon precursor by electrospinning, followed by suitable heat treatments. As the lignin content in the precursor increases, the carbon nanofibers become thinner, as seen from scanning electron microscopy images. However, their carbon structure and electrochemical performance are found to be very similar, even though surface functional groups on carbon nanofibers are slightly different from each other. For example, in the initial charge (lithium insertion) and discharge (lithium deinsertion) process, the reversible specific capacities of the various carbon nanofibers come from different precursor ratios of lignin and polyacrylonitrile are similar. Even at a fast (7 min) charge and discharge condition, the carbon nanofibers prepared from the lignin-containing precursors show a discharge capacity of 150 mAh g−1. The lignin-based carbon nanofibers thus show promise for use in high-power lithium ion battery anodes with low price.
The imminent industrial production of cellulosic ethanol from annual plants will generate massive amounts of herbaceous lignins that will have to be valorized. However, the chemical and physical properties of herbaceous lignins are much less known than those of wood lignins. In the present study, organosolv lignins were extracted from wheat, triticale, corn, flax, and hemp residues using microwave irradiation under similar conditions. The extracted lignins were extensively analyzed by FT-IR, 31P NMR, gel permeation chromatography, thermogravimetric analysis, and elemental and carbohydrate analysis to determine their applicability in polymers. All lignins were of high purity with low sugar, sulfur, and ash content. Corn, hemp, and flax lignins were found to contain high concentrations of non-methoxylated phenolic groups, syringyl phenolic groups, and aliphatic OH groups, respectively, making them promising candidates for production of phenolic resins, stabilization of polyolefins, and polyurethane synthesis, respectively. Triticale or wheat lignins were less specific, with a balanced content of OH groups, which makes them applicable to polyester synthesis.
A series of hard carbons with different porous structure are prepared and tested for an anode of lithium ion batteries. Nitrogen adsorption/desorption isotherms and transmission electron microscope images reveal that the porous carbons prepared using different template exhibit typical mesoporous structure and hierarchical porous structure respectively. The results of charge–discharge tests and diffusion coefficients show that the electrochemical behavior is strongly dependent on the porous texture of carbons. The obtained hierarchical porous carbons exhibit a highest capacity of 503.5 mAh g−1 at 0.2C rate and still keep a capacity of 332.8 mAh g−1 at 5C rate. The enhanced electrode performance of the porous hard carbons derives from better structural flexibility and shorter diffusion pathways in the advantageous nano-porous texture.
We synthesize a carbon anode material with unique nanostructure for high power lithium ion batteries. The carbon material is composed of numerous clusters of carbon nanobeads, and shows a macro-meso-micro hierarchical porous structure. This unique nanostructure appears to facilitate the rapid transfer of lithium ions and a very large ion adsorption. It exhibits a reversible capacity of 407.4mAhg−1 and its rate performance is drastically improved in comparison with that of the commercial graphite. The unique structure enables the anode to combine the advantages of both lithium ion batteries and electrochemical double layer capacitors, resulting in the good electrochemical performance.
Carbonaceous materials have been obtained by the pyrolysis of coconut shells at 800 and 900°C with pore forming substances such as KOH and ZnCl2. The prepared carbons were subjected to XRD, SEM, BET-surface area and charge–discharge studies. The structure and morphology were greatly changed by porogens, which in turn influence the electrochemical properties of the carbonaceous materials. Nanocrystalline tin (Sn) particles were prepared by chemical reduction method. The cycling tests showed that the addition of nanotin with the active material offers a stable cycling behavior. The electrochemical impedance spectra for the Li/C cells have been made and the results are discussed.
Biomass from herbaceous crops is the largest renewable source for the production of bioproducts and biofuels. The available information about lignins in straw of herbaceous crops is scattered and the available reviews generally address wood lignins. This review is focused on the structural characteristics and separation of lignin in the straws of corn, wheat, rice and flax, and it is the first attempt to generalize the information about lignin structure of important herbaceous crops and processes for the separation of lignin from hemicellulose and cellulose in lignocellulosic crop residues. The differences in lignin structures and processes for the fractionation of the major components of straw are highlighted, and the conversion of lignin into value-added products is addressed.
The state of lithium in a novel hard-carbon optimized to the anode of large size Li ion secondary battery, which has been recently commercialized, was investigated and compared with other existing hard-carbon samples by 7Li NMR method. The new carbon material showed a peak at 85ppm with a shoulder signal at 7ppm at room temperature in static NMR spectrum, and the former shifted to 210ppm at 180K. The latter at room temperature was attributed to Li doped in small particles contained in the sample. The new carbon sample showed weaker intensity of cluster-lithium signal than the other hard-carbon samples in NMR, which corresponded to a tendency of less “constant voltage” (CV) capacity in charge–discharge curves of electrochemical evaluation. Smaller CV capacity and initial irreversible capacity, which are the features of the novel hard-carbon, are considered to correspond to a blockade of the diffusion of Li into pore of carbon.
An investigation is made on the interfacial phenomena of commercially available mesocarbon microbeads (MCMB) as the carbon lithium electrode in an electrolyte, which consists of 1 M LiPF6 dissolved in an equal mixture of ethylene carbonate (EC) and diethyl carbonate (DEC). Once the charge–discharge of lithium (Li) proceeds, a surface film is formed on the MCMB carbon electrode, and its thickness increases with cycle number. The growth of the surface film with cycle number is observed by a scanning electron microscope and the surface resistance by means of AC impedance measurements. A continuous decrease in the charge capacity with cycle number is found and is related to film growth. The surface films are composed of solvated Li compounds, as shown by surface-sensitive Fourier transform infrared (FT-IR) spectroscopy.
We have prepared carbon anode materials by pyrolysis of rice husk (RH). Through X-ray powder diffraction, Brunauer–Emmett–Teller (BET) measurement, and ICP-AES analysis, the effects of acid–base pre-treatment, pyrolysis temperature, and the use of a proprietary pore-genic agent on the cell capacity of these materials were investigated. The carbonaceous materials made from RH treated with a proprietary agent showed an extraordinarily high reversible capacity of 1055mAh/g. To our best knowledge, this new hard carbon material possesses the highest reversible capacity ever reported for any carbon anode materials of lithium-ion batteries.
The irreversible capacity loss that occurs during the first cycle in an Li ion battery was studied using Fourier transform infrared attenuated total reflectance, secondary ion mass spectrometer, X-ray photoelectron spectroscopy, and plasma spectrometer. The irreversible capacity loss was related to both the solvent decomposition and the reaction of Li with active sites in the bulk of the carbon electrode. Li remaining in the discharged electrode not only exists on the surface of the carbon but also in its bulk. The Li concentration on the surface of the carbon is higher than that in the bulk. The binding energy of Li remaining in the bulk of the discharged carbon electrode is higher by â¼ 2.5 eV than that of metallic lithium (52.5 eV) and lower by â¼ 0.5 eV than that of Li remaining on the surface of the discharged electrode.
We demonstrate a single step, efficient, catalyst-and-solvent-free and scalable process for the synthesis of monodisperse, prolate spheroid shaped carbon (PSC) with 3 μm polar and 1.5 μm equatorial diameters by thermolysis of refined corn oil in a closed SS reactor at 700 °C. The autogenic pressure and in situ mass spectra during the thermolysis of corn oil were measured to gain insight on the reaction products as a function of temperature. We have characterized the morphology, structure, composition and magnetic property of PSC by using SEM, EDX, XRD, pair distribution function (PDF), solid state 13C NMR, Raman spectroscopy and EPR. We propose a putative mechanism for their formation by using all the complementary data.
Amorphous carbon films were deposited successfully on Cu foils by DC magnetron sputtering technique. Electrochemical performance of the film as lithium battery anode was evaluated across Li metal at 0.2C rate in a non-aqueous electrolyte. The discharge curves showed unusually low irreversible capacity in the first cycle with a reversible capacity of ∼810mAhg−1, which is at least 2 times higher than that of graphitic carbon. For the first time we report here an amorphous carbon showing such a high reversibility in the first cycle, which is very much limited to the graphitic carbon. The deposited films were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and step profilometer for the structural and surface properties. The hydrogen content of the synthesized films was studied using residual gas analysis (RGA). The low hydrogen content and the low specific surface area of the synthesized amorphous carbon film are considered responsible for such a high first cycle columbic efficiency. The growth mechanism and the reasons for enhanced electrochemical performance of the carbon films are discussed.
The pyrolysis of local white sugar was studied at various heat-treatment temperatures in nitrogen and argon atmospheres. The pyrolyzed sugar carbons (PSCs) were characterized by TGA, XRD, SEM, Raman, elemental, and BET surface area analyses. The effects of atmosphere and heat-treatment temperature on the structure, morphology, and cell performance are discussed.
High capacities with large hysteresis were observed during lithium insertion in hydrogen-containing carbons heated at temperatures near 700 °C. Quasi open-circuit voltage (OCV) measurements were used to study these materials. Using a simple model developed previously [1], we can qualitatively model the result of the OCV measurement. It is believed that the lithium atoms bind near aromatic hydrogen at edge of each graphene layer in the materials. This activated process involves a carbon-carbon bonding change from (sp)2 to (sp)3 leading to large hysteresis during lithium insertion.
Lithium can be inserted reversibly within most carbonaceous materials. The physical mechanism for this insertion depends on
the carbon type. Lithium intercalates in layered carbons such as graphite, and it adsorbs on the surfaces of single carbon
layers in nongraphitizable hard carbons. Lithium also appears to reversibly bind near hydrogen atoms in carbonaceous materials
containing substantial hydrogen, which are made by heating organic precursors to temperatures near 700°C. Each of these three
classes of materials appears suitable for use in advanced lithium batteries.
The anodic performance of soft carbons prepared from synthetic mesophase pitches by heat-treatment at 500 to 1200°C are investigated in order to clarify their mechanism for the insertion of lithium ions. It is found that the insertion mechanism for soft carbon heat-treated at low temperatures is divided into the following three cases: (i) lithium ions partially charge transferred on the surface of hexagonal planes or in the unstacked carbon layers to be charged and discharged at 0.25 to 0.8 V (Type I); (ii) intercalated into carbon layers up to a higher stage to be charged and discharged at 0.0 to 0.25 V (Type II); (iii) inserted into the microspaces located at the edges of carbon clusters to be charged at 0.0 to 0.1 V and discharged at 0.8 to 2.0 V (Type III). Lithium ions of Types I and II are charged and discharged reversibly, hence, the capacity is stable with cycling. By contrast, the capacity of Type III ions decreases gradually with cycle number. The irreversible charge–discharge and poor cycle stability of Type III ions suggest some chemical reactions during charge–discharge that increase the discharge potential and modify the carbon structure. Bonding of carbon planes at facing edges in the anisotropic carbon may be responsible for the poor cycle stability. The capacity of Type II ions increases gradually with heat-treatment which graphitizes carbon to allow intercalation. By contrast, the capacities of Types I and III ions are decreased gradually and sharply, respectively, by heat-treatment. The progress of graphitization densifies the carbon and reduces the free surface of the hexagonal sheet and the charging to such sites. The performance of Type III ions reflects the characteristic of anisotropic carbon in which the clusters are aligned to have more faced edges than those in isotropic carbon. The heat-treatment combines the edges to enlarge considerably the hexagonal plane in this temperature range.
Thermogravimetry/mass spectrometry was applied to characterize six lignins prepared for an international round robin test. The sample set includes a mildly isolated lignin, and technical lignins prepared by steam explosion, Alcell, Indulin and Sucrolin processes. The samples were thermally degraded in an argon atmosphere using a heating rate of 20 °C min−1. The weight loss and the evolution profiles of the thermal decomposition products of low molecular mass were monitored. It was found that the intensity and the evolution profile of the products (especially water, formaldehyde, methane and methanol) reflect the severity of the isolation procedure and the origin of the lignin. Correlations have been observed between the abundance of volatile products and the type and amount of functional groups. The terminal CH2OH groups decompose by the release of both water and formaldehyde, as demonstrated by the relationship between the aliphatic hydroxyl group content and the formaldehyde as well as the water evolution. The dependence of the methane yield on the methoxyl group content provided evidence that the scission of methoxyl groups results in the formation of methane as well as methanol. The correlations found allow the assignments of the gaseous products to functional groups.
Electrodic characteristics of various carbon materials have been investigated to study the correlation between structures of carbon materials and performances of negative electrodes of lithium rechargeable batteries. In the case of highly graphitized carbon materials, the discharge capacity was determined mainly by their crystallinity with no dependence on textures and natural graphite; the highest graphitization at about 360 mAh/g was stage-1 lithium-intercalated graphite, C6Li (theoretical maximum 372 mAh/g). The coulombic efficiency at the first cycle was strongly dependent on the textures of the carbon materials, and pitch-based carbon fiber of a radial structure showed an excellent coulombic efficiency over 96% by selecting appropriate electrolytes. The performances of the pitch-based carbon fiber were also excellent in the electrolytes consisting of mixed solvents containing propylene carbonate. On the other hand, the pitch coke heat-treated at 550 °C had an initial capacity over 550 mAh/g, which was beyond the theoretically maximum capacity of 372 mAh/g for C6Li, although the capacity decreased rapidly to less than 250 mAh/g within ten cycles. Polyacrylonitrile (PAN)-based carbon fiber showed a stable capacity with cycling over 350 mAh/g in spite of low graphitization. The initial coulombic efficiency seemed to increase in accordance with decrease of hydrogen and oxygen in the pitch coke, and oxygen and nitrogen in the polyacrylonitrile (PAN) fibers. These phenomena seemed to suggest that carbon materials of disordered structure would have higher capacity than that of the graphitic carbon materials.
We describe the preparation of hard carbon samples from epoxy resins. These materials are shown by wide angle X-ray diffraction to be constructed of graphene sheets of small lateral extent (about 25 Å in diameter). By controlling the synthesis conditions, it is possible to prepare materials wherein the fraction of graphene sheets present as single layers can be adjusted. Using small angle X-ray scattering, we show that these materials incorporate small nanopores between the single layers, which are about 15 Å in diameter. This suggests that the single layers are arranged more or less like a “house of cards”. Lithium can be inserted reversibly into these materials and the amount of lithium that can be inserted increases as the fraction of single layers in the sample increases. This suggests that the mechanism of lithium insertion in these materials is surface adsorption of lithium on the internal surfaces of the single-layer graphene sheets. We compare the insertion of lithium in these carbons to that which occurs in soft carbons with insignificant numbers of single layers and no measurable nanoporosity.
This review covers the production and utilisation of liquids from the thermal processing of biomass and related materials to substitute for synthetic phenol and formaldehyde in phenol formaldehyde resins. These resins are primarily employed in the manufacture of wood panels such as plywood, MDF, particle-board and OSB. The most important thermal conversion methods for this purpose are fast pyrolysis and vacuum pyrolysis, pressure liquefaction and phenolysis. Many feedstocks have been tested for their suitability as sources of phenolics including hard and softwoods, bark and residual lignins. Resins have been prepared utilising either the whole liquid product, or a phenolics enriched fraction obtained after fractional condensation or further processing, such as solvent extraction. None of the phenolics production and fractionation techniques covered in this review are believed to allow substitution of 100% of the phenol content of the resin without impacting its effectiveness compared to commercial formulations based on petroleum derived phenol. This survey shows that considerable progress has been made towards reaching the goal of a price competitive renewable resin, but that further research is required to meet the twin challenges of low renewable resin cost and satisfactory quality requirements. Particular areas of concern are wood panel press times, variability of renewable resin properties, odour, lack of reactive sites compared to phenol and potential for increased emissions of volatile organic compounds.
Commercial carbon cloth made of PAN-based carbon fibres was used as free-standing anode for lithium
intercalation. The role of surface functional groups on the specific irreversible charge loss and reversible
charge during the intercalation and de-intercalation of lithium ions into carbon cloth has been investigated.
Oxygen groups have been introduced by nitric acid vapour treatment and subsequently gradually
removed by thermal treatment at different temperatures in He or H2 atmosphere as confirmed by
X-ray photoelectron spectroscopy. A clear correlation between the amount of surface-bound oxygen
groups and the irreversible specific charge was observed. Three irreversible processes were distinguished
during the first cathodic scan: (i) reduction of oxygen groups, (ii) formation of the solid
electrolyte interphase (SEI) and (iii) presumably exfoliation. The latter one was only observed for samples
with low surface oxygen concentration, and its contribution to the irreversible capacity was small
due to the low graphitization degree of the samples. An increased specific reversible charge upon
increasing the amount of oxygen-containing groups was observed with the main improvement above
1.5 V.
We report for the first time initial lithium intake capacities for pyrolytic carbonaceous materials far exceeding even the theoretical value for metallic lithium. The carbonaceous materials were synthesized by pyrolysis of peanut shells under argon. Thermal conditions for the pyrolysis were optimized in order to obtain materials with desirable electrochemical properties. Peanut shells carbonized in a two-step process that occurred between 300 and 600 °C. The shells were also treated with a proprietary porogenic agent with the goal of altering the pore structure and surface area of the pyrolysis products. Both the untreated and the porogen-treated shells yielded carbons with poor crystallinity, although the surface area and the pore diameter of the latter registered a 66-fold and two-fold increase, respectively, over the former. Both the carbons had a predominance of non-parallel single sheets of carbons, as determined by the values of their R factors. Charge–discharge studies showed that although the capacities registered with carbons from the untreated shells varied with the H/C ratio, it was generally reasonable to relate the high initial capacities (in some cases as much as 4765 mAh/g) to the extra surface area of unorganized single layers of carbon and nanoscopic cavities generated by the pore-former. It is also believed that the ‘extra’ capacity may stem from lithium interaction with surface groups and from lithium plating on the carbon surface and subsequent passivation.
Carbon materials capable of efficient hydrogen electrosorption at ambient conditions can be used for negative electrode material in chemical power sources, competitive for metallic hydride alloys. This paper describes physical, chemical and electrochemical properties of active carbon (LAC) produced from lignin processed by standard carbonization and KOH activation at temperature of 950 °C. Microporous carbon with BET surface of 1946 m2/g obtained in such conditions has a complex porous structure with a considerable number of supermicropores and small mesopores (ca. 50%). As a result, efficient hydrogen electrosorption of 510 mA h/g (1.89 wt% in meaning of energy storage) is obtained and favorable discharge characteristics at current densities up to 1 A/g.
Since the birth of lithium ion battery in the end of 1980s and early 1990s many kinds of anode materials have been studied. Nevertheless, graphitic carbon is still the only commercially available product. As a result, modification of carbonaceous anode materials has been a research focus. In this paper, latest progress on carbon anode materials for lithium ion batteries is briefly reviewed including research on mild oxidation of graphite, formation of composites with metals and metal oxides, coating by polymers and other kinds of carbons, and carbon nanotubes. These modifications result in great advances; novel kinds of carbon anodes will come in the near future, which will propel the development of lithium ion batteries.
Activated carbons were prepared from lignin by chemical activation with ZnCl2, H3PO4 and some alkali metal compounds. The influence of carbonization and activating reagent on the pore structure of the activated carbon was investigated. It was found that the maximum surface areas were obtained at the carbonization temperature of 600\textdegreeC in both ZnCl2 and H3PO4 activation, and that the surface areas were as large as those of the commercial activated carbons. On the other hand, in alkali metal activation it was found that the maximum surface areas were obtained at the carbonization temperature of 800\textdegreeC. Except for Na2CO3 maximum surface areas were much larger than those of the commercial activated carbons. The activated carbon prepared by K2CO3 activation showed a surface area of nearly 2000 m2/g. It was shown that ZnCl2 works effectively as dehydration reagent below 600\textdegreeC. On the other hand, K2CO3 works effectively in two temperature ranges, below 500\textdegreeC and above 600\textdegreeC. Below 500\textdegreeC, the carbonization behavior was modified by impregnation with K2CO3, but the pore structure changes little. Above 600\textdegreeC, carbon was consumed by K2CO3 reduction and then the surface area was increased.
Properties of a novel hard-carbon optimized to large size Li ion secondary battery studied by 7 Li NMR
- J Yang
- X Y Zhou
- J Li
- Y L Zou
- J J Tang
J. Yang, X.Y. Zhou, J. Li, Y.L. Zou, J.J. Tang, Properties of a novel hard-carbon
optimized to large size Li ion secondary battery studied by 7 Li NMR, Mater.
Chem. Phys. 135 (2012) 445-450.
- X J Pan
- J N Saddler
X.J. Pan, J.N. Saddler, Effect of replacing polyol by organosolv and kraft lignin on
the property and structure of rigid polyurethane foam, Biotechnol. Biofuels 6
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