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Preparation of intergrown P/O-type biphasic layered oxides as a high-performance cathode for sodium ion batteries
Abstract
This study reports on the solid-state synthesis and characterization of novel quaternary P/O intergrown biphasic Na0.8MnyNi0.8-yFe0.1Ti0.1O2 (y = 0.6, 0.55, 0.5, 0.45) cathode materials. Electrochemical test reveal superior performance of...
... Nonetheless, the limited cycling stability of Fe/Mn layered oxide cathodes remains a primary obstacle. As shown in Figure 2D, Zhang et al. successfully synthesized P2/O3 two-phase Na 0.67 Fe 0.425 Mn 0.425 Cu 0.15 O 2 layered oxides using the sol-gel method [76] . The SAED patterns of the P2 + O3 NaLiMNC composite: O3-type structure and P2-type structure; The STEM images: HADDF andABF images of P2 + O3 NaLiMNC composite; the blue and red rectangle represent O3 structure and P2 structure areas (Reproduced with permission from Ref. [73] . ...
... NFM-0.1, NFM-0.15 (Reproduced with permission from Ref. [76] . Copyright 2024, Elsevier). ...
Sodium-ion batteries (SIBs) are recognized as a leading option for energy storage systems, attributed to their environmental friendliness, natural abundance of sodium, and uncomplicated design. Cathode materials are crucial in defining the structural integrity and functional efficacy of SIBs. Recent studies have extensively focused on manganese (Mn)-based layered oxides, primarily due to their substantial specific capacity, cost-effectiveness, non-toxic nature, and ecological compatibility. Additionally, these materials offer a versatile voltage range and diverse configurational possibilities. However, the complex phase transition during a circular process affects its electrochemical performance. Herein, we set the multiphase Mn-based layered oxides as the research target and take the relationship between the structure and phase transition of these materials as the starting point, aiming to clarify the mechanism between the microstructure and phase transition of multiphase layered oxides. Meanwhile, the structure-activity relationship between structural changes and electrochemical performance of Mn-based layered oxides is revealed. Various modification methods for multiphase Mn-based layered oxides are summarized. As a result, a reasonable structural design is proposed for producing high-performance SIBs based on these oxides.
... P2、O3和混合相材料的电化学性能. (a) 三种材料的循环容量; (b) 三种材料的首次充放电曲线[33] (网络版彩图) Electrochemical properties of P2, O3 and phase-mixed materials. (a) Cyclic capacity of the three materials; (b) initial charge-discharge curves of the three materials[33] (color online). ...
... (a) 三种材料的循环容量; (b) 三种材料的首次充放电曲线[33] (网络版彩图) Electrochemical properties of P2, O3 and phase-mixed materials. (a) Cyclic capacity of the three materials; (b) initial charge-discharge curves of the three materials[33] (color online). ...
... V vs Na + / Na range. 63 During the first two cycles, the two peaks observed between 2.5 and 3.7 V do not decrease significantly in intensity, indicating good initial reversibility. As shown in Figure 4a, the NLNMO electrode in combination with conventional NaClO 4 /PC electrolyte delivers a specific capacity of ∼90 mAh g −1 at C/10, which decreases to 50 mAh g −1 at 1C rate. ...
Modern technologies that can replace state-of-the-art Li-ion batteries (LIBs), such as Na-ion batteries (NIBs), are currently driving new advancements in energy storage research. Developing functional active materials having sustainable features and enhanced performances able to assess their exploitation in the large-scale market represents a major challenge. Rationally designed P2-type layered transition metal (TM) oxides can enable high-energy NIB cathodes, where the tailored composition directly tunes the electrochemical and structural properties. Such positive electrodes need stable electrolytes, and exploration of unconventional room-temperature ionic liquid (RTIL)-based formulations paves the route toward safer options to flammable organic solvents. Notwithstanding the fact that Li⁺ doping in these materials has been proposed as a viable strategy to improve structural issues, an in-depth understanding of structure–property relationship as well as electrochemical testing with innovative RTIL-based electrolytes is still missing. Herein, we propose the solid-state synthesis of P2-Na0.84Li0.1Ni0.27Mn0.63O2 (NLNMO) cathode material, which exhibits promising structural reversibility and superior capacity retention upon cycling when tested in combination with RTIL-based electrolytes (EMI-, PYR14-, and N1114-FSI) compared to the standard NaClO4/PC. As unveiled from DFT calculations, lattice integrity is ensured by the reduced Jahn–Teller distortion upon Na removal exerted by Mn⁴⁺ and Li⁺ sublattices, while the good redox reversibility is mainly associated with the electrochemically active Ni²⁺/Ni³⁺/Ni⁴⁺ series burdening the charge compensation upon desodiation. By declaring the electrochemical compatibility of the P2-NLNMO cathode with three RTIL-based electrolytes and dissecting the role of Li/Ni/Mn sublattices in determining the electrochemical behavior, our comprehensive study enlightens the potential application of this electrode/electrolyte setup for future high-energy NIB prototype cells.
... In biphasic composites, synergistic benefits of constituent phases can be exploited to optimize structural and electrochemical properties. For example, while the primary phase acts as active cathode, the secondary phase may impart structural stability during Na + (de)insertion and/or can suppress volume change during battery cycling [10]. Recently, bi-or multiphasic hybrid composites were employed to yield high electrochemical performance and cycling stability [11,12]. ...
Sodium-ion batteries are pursued as pragmatic alternative to the Li-ion battery technology having operational similarity along with natural resource abundance. P2-type manganese-rich layered oxides are widely explored exhibiting high capacity along with fast rate kinetics. To improve their electrochemical performance and reduce voltage decay upon cycling and to mitigate irreversible phase transitions, cation doping or hybrid composite integrations have been proposed. Here, we report a unique Mn-rich layer-spinel composite, Na0.7(Li1/18Mn11/18Ni3/18Fe2/18χ1/18)O2–xNa2MoO4, leading to a synergistic effect of layered P2 and spinel phases. This stable layer/spinel biphasic composite was stabilized through Mo doping and its electrochemical activity was studied at different voltage windows. When cycled between 1.5–4.5 V, this composite delivered a high specific capacity of 183 mAh.g–1 involving both cationic and anionic (O2–/O2n–) redox. The structural evolution during (dis)charge was studied by ex-situ X-ray diffraction and cyclic voltammetry. It is observed that mitigating P2-P2′′ phase transition at higher voltage is crucial to improve the electrochemical performance, cycling stability and reduce the voltage hysteresis.
... Therefore, the reversibility of the phase transformation is greatly enhanced, delivering the better cycling stability for NLFMTO. Different from the previous reports about the P2/O3 biphasic cathodes [43,[58][59][60], the relationship between the biphasic complex way and the enhanced electrochemical performance is clearly illustrated here. ...
As the representative layered oxide cathode for sodium ion batteries (SIBs) featuring the low cost, P2-type Na-Fe-Mn oxide (NFMO) delivers a high capacity but a limited cycling stability, while O3-type NFMO shows extended cycling lifespan but a lower capacity. Considering the complementarity of two phases in electrochemistry, we successfully designed and fabricated a Fe/Mn-based layered oxide Na0.67Li0.11Fe0.36Mn0.36Ti0.17O2 with a unique P2/O3 biphasic architecture through high-proportion Li/Ti co-substitution. High-proportion Li substitution in transition metal layers triggers the reversible O redox below 4.2 V due to the formation of the special O bonding environment, delivering a highest capacity of 235 mA h g¹ ever reported among all Fe- and Mn-based layered oxide cathodes. Moreover, the unique intersected complex way at the phase boundary significantly suppressed the P2→OP4 phase transition and decreased the lattice mismatch between two phases at high potentials, greatly enhancing the cycling stability. This novel phase complex strategy benefits the design of promising cathode materials with high capacity and long lifespan for SIBs and beyond.
Sodium‐ion batteries (SIBs) have emerged as a compelling alternative to lithium‐ion batteries (LIBs), exhibiting comparable electrochemical performance while capitalizing on the abundant availability of sodium resources. In SIBs, P2/O3 biphasic cathodes, despite their high energy, require furthur improvements in stability to meet current energy demands. This study introduces a systematic methodology that leverages the meta‐heuristically assisted NSGA‐II algorithm to optimize multi‐element doping in electrode materials, aiming to transcend conventional trial‐and‐error methods and enhance cathode capacity by the synergistic integration of P2 and O3 phases. A comprehensive phase analysis of the meta‐heuristically designed cathode material Na0.76Ni0.20Mn0.42Fe0.30Mg0.04Ti0.015Zr0.025O2 (D‐NFMO) is presented, showcasing its remarkable initial reversible capacity of 175.5 mAh g⁻¹ and exceptional long‐term cyclic stability in sodium cells. The investigation of structural composition and the stabilizing mechanisms is performed through the integration of multiple characterization techniques. Remarkably, the irreversible phase transition of P2→OP4 in D‐NFMO is observed to be dramatically suppressed, leading to a substantial enhancement in cycling stability. The comparison with the pristine cathode (P‐NFMO) offers profound insights into the long‐term electrochemical stability of D‐NFMO, highlighting its potential as a high‐voltage cathode material utilizing abundant earth elements in SIBs. This study opens up new possibilities for future advancements in sodium‐ion battery technology.
All solid-state batteries (ASSBs) represent the next generation of technology, offering tremendous potential in safety and energy density. However, successfully integrating high-capacity cathode materials without compromising long-term stability remains a...
Cycling stability is the biggest challenge for cathodes of sodium‐ion batteries (SIBs), which is directly affected by the structure design. Herein, the combination of high‐entropy (HE) and multiphase structure is demonstrated to be helpful for maintaining the structure and improving the cycling stability. In the Ni/Mn/Cu/Ti/Sn five‐component HE multiphase cathode, the multiple elements at transition metal sites can enlarge the lattice and stabilize the structure simultaneously without causing an obvious capacity drop, achieving the synergistic effect of multi‐cations. In the HE cathodes consisting of P2 and O3 phases, the harmful phase transition in high‐voltage is suppressed and the cycling performance is improved. A capacity retention of 77.3 mAh g⁻¹ after 300 cycles is delivered, and an improved rate performance of 88.7 mAh g⁻¹ at 750 mA g⁻¹ is observed, better than that of the low‐entropy multiphase cathode(P2 and O3) and the HE oxide single O3‐phase cathode. The weighted average ionic radius(WAIR) of all transition metals is demonstrated critical for the formation of the phase composition in HE composites. Through comparing a series of HE and multiphase cathodes, an empirical range of WAIR is obtained, which shows guidance for the design of other cathode materials.
P2‐type cobalt‐free MnNi‐based layered oxides are promising cathode materials for sodium‐ion batteries (SIBs) due to their high reversible capacity and well chemical stability. However, the phase transformations during repeated (dis)charge steps lead to rapid capacity decay and deteriorated Na⁺ diffusion kinetics. Moreover, the electrode manufacturing based on polyvinylidene difluoride (PVDF) binder system has been reported with severely defluorination issue as well as the energy intensive and expensive process due to the use of toxic and volatile N‐methyl‐2‐pyrrolidone (NMP) solvent. It calls for designing a sustainable, better performing, and cost‐effective binder for positive electrode manufacturing. In this work, we investigated inorganic sodium metasilicate (SMS) as a viable binder in conjunction with P2‐Na0.67Mn0.55Ni0.25Fe0.1Ti0.1O2 (NMNFT) cathode material for SIBs. The NMNFT‐SMS electrode delivered a superior electrochemical performance compared to carboxy methylcellulose (CMC) and PVDF based electrodes with a reversible capacity of ~161 mAh/g and retaining ~83 % after 200 cycles. Lower cell impedance and faster Na⁺ diffusion was also observed in this binder system. Meanwhile, with the assistance of TEM technique, SMS is suggested to form a uniform and stable nanoscale layer over the cathode particle surface, protecting the particle from exfoliation/cracking due to electrolyte attack. It effectively maintained the electrode connectivity and suppressed early phase transitions during cycling as confirmed by operando XRD study. With these findings, SMS binder can be proposed as a powerful multifunctional binder to enable positive electrode manufacturing of SIBs and to overall reduce battery manufacturing costs.
Sodium‐ion batteries (SIBs) work similarly to lithium‐ion batteries, but they cost less and are safer. However, the battery has some shortcomings, such as low energy density and poor stability, which hinder its development and application. The development of electrode materials with low cost and high‐performance characteristics is a hot and difficult point in the research of SIBs. In this paper, the existing sodium ion cathode and anode materials are systematically reviewed. Firstly, the electrochemical structures and properties of various cathode and anode materials were introduced, and the limitations of cathode and anode materials of SIBs were analyzed. Based this, the current modification methods were summarized, such as surface coating of materials, doping of heteroatoms and metal elements to improve the electrochemical performance. In this paper, the research progress and modification measures of SIBs are summarized and prospected. It is helpful to further improve its comprehensive performance and lay a foundation for the future application of cathode and anode materials for SIBs.
Sodium-ion batteries (SIBs) have attracted great attention being the most promising sustainable energy technology owing to their competitive energy density, great safety and considerable low-cost merits. Nevertheless, the commercialization process of SIBs is still sluggish because of the difficulty in developing high-performance battery materials, especially the cathode materials. The discovery of layered transition metal oxides as the cathode materials of SIBs brings infinite possibilities for practical battery production. Thereinto, the O3-type layered transition metal oxides exhibit attractive advantages in terms of energy density benefiting from their higher sodium content compared to other kinds of layered transition metal oxides. Enormous research studies have largely put forward their progress and explored a wide range of performance improvement approaches from the morphology, coating, doping, phase structure and redox aspects. However, the progress is scattered and has not logically evolved, which is not beneficial for the further development of more advanced cathode materials. Therefore, our work aims to comprehensively review, classify and highlight the most recent advances in O3-type layered transition metal oxides for SIBs, so as to scientifically cognize their progress and remaining challenges and provide reasonable improvement ideas and routes for next-generation high-performance cathode materials.
Sodium ion batteries (SIBs) have attracted great interest as candidates in stationary energy storage systems relying on low cost, high abundance and outstanding electrochemical properties. The foremost challenge in advanced NIBs lies in developing high-performance and low-cost electrode materials. To accelerate the commercialization of sodium ion batteries, various types of materials are being developed to meet the increasing energy demand. O3-type layered oxide cathode materials show great potential for commercial applications due to their high reversible capacity, moderate operating voltage and easy synthesis, while allowing direct matching of the negative electrode to assemble a full battery. Here, representative progress for Ni/Fe/Mn based O3-type cathode materials have been summarized, and existing problems, challenges and solutions are presented. In addition, the effects of irreversible phase transitions, air stability, structural distortion and ion migration on electrochemical performance are systematically discussed. We hope to provide new design ideas or solutions to advance the commercialization of sodium ion batteries.
Though layered sodium oxide materials are identified as promising cathodes in sodium-ion batteries, biphasic P3/O3 depicts improved electrochemical performance and structural stability. Herein, a coexistent P3/O3 biphasic cathode material was synthesized with "LiF" integration, verified with X-ray diffraction and Rietveld refinement analysis. Furthermore, the presence of Li and F was deduced by inductively coupled plasma-optical emission spectrometry (ICP-OES) and energy dispersive X-ray spectroscopy (EDS). The biphasic P3/O3 cathode displayed an excellent capacity retention of 85% after 100 cycles (0.2C/30 mA g-1) at room temperature and 94% at -20 °C after 100 cycles (0.1C/15 mA g-1) with superior rate capability as compared to the pristine cathode. Furthermore, a full cell comprising a hard carbon anode and a biphasic cathode with 1 M NaPF6 electrolyte displayed excellent cyclic stabilities at a wider temperature range of -20 to 50 °C (with the energy density of 151.48 Wh kg-1) due to the enhanced structural stability, alleviated Jahn-Teller distortions, and rapid Na+ kinetics facilitating Na+ motion at various temperatures in sodium-ion batteries. The detailed post-characterization studies revealed that the incorporation of LiF accounts for facile Na+ kinetics, boosting the overall Na storage.
Lithium-ion batteries (LIBs) have dominated the secondary batteries market in the past few decades. However, the widespread application is seriously hampered by the limited lithium resource and high cost. Recently, sodium-ion batteries (SIBs) have generated significant attention because of their abundant raw sources, low cost, and similar “rocking chair” mechanism with LIBs, which holds great application potential in large-scale energy storage. Cathode materials with good structural stability, high capacities, and redox potentials are in urgent demand for next-generation SIBs. Therefore, understanding the structure-dependent intercalation electrochemistry and recognizing the existing issues relating to cathode materials are indispensable prerequisites. Herein, this review provides a comprehensive overview of the recent advances of the most promising SIBs cathode candidates, including layered oxides, polyanionic materials, and Prussian blue analogues. The currently existing issues that need to be addressed for these cathodes are pointed out, such as insufficient energy density, low electron conductivity, air sensitivity, and so on. This review also details the structural characteristics of these three cathode candidates. Moreover, the recent optimization strategies for improving the electrochemical performance are summarized, including element doping, morphology modification, structure architecture, and so on. Finally, the current research status and proposed future developmental directions of these three cathode materials are concluded. This review aims to provide practical guidance for the development of cathode materials for next-generation SIBs.
Sodium‐ion batteries (SIBs) are considered as a low‐cost complementary or alternative system to prestigious lithium‐ion batteries (LIBs) because of their similar working principle to LIBs, cost‐effectiveness, and sustainable availability of sodium resources, especially in large‐scale energy storage systems (EESs). Among various cathode candidates for SIBs, Na‐based layered transition metal oxides have received extensive attention for their relatively large specific capacity, high operating potential, facile synthesis, and environmental benignity. However, there are a series of fatal issues in terms of poor air stability, unstable cathode/electrolyte interphase, and irreversible phase transition that lead to unsatisfactory battery performance from the perspective of preparation to application, outside to inside of layered oxide cathodes, which severely limit their practical application. This work is meant to review these critical problems associated with layered oxide cathodes to understand their fundamental roots and degradation mechanisms, and to provide a comprehensive summary of mainstream modification strategies including chemical substitution, surface modification, structure modulation, and so forth, concentrating on how to improve air stability, reduce interfacial side reaction, and suppress phase transition for realizing high structural reversibility, fast Na⁺ kinetics, and superior comprehensive electrochemical performance. The advantages and disadvantages of different strategies are discussed, and insights into future challenges and opportunities for layered oxide cathodes are also presented.
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The abundance of sodium resources provides the basis for the large‐scale application of sodium‐ion batteries (SIBs) in the field of energy storage. Among the cathode candidates for SIBs, oxide materials stand out because of their ease of synthesis, environmental friendliness and high capacity. According to the crystal structure, oxide cathode materials can be mainly classified as P2, P3, O3 and tunnel phases. Benefiting from the combined advantages of different phases, composite oxide cathode materials have been widely studied due to the enhanced both cycling and rate performance. In this review, we analyzed the three key issues of phase regulation, electrochemical performance and reaction mechanism based on the recent progress for composite oxide cathode materials. The composite oxide cathode materials will be one of the most competitive and attractive cathodes for SIBs.
Sodium layered oxides generally suffer from deep-desodiation instability in P2 structure and sluggish kinetics in O3 structure. It will be great to design P2/O3 biphasic materials that bring the complementary merits of both structures. However, such exploration is hindered by the ambiguous mechanism of material formation. Herein, supported by theoretical simulations and various spectroscopies, we prove that P2/O3 biphasic structures essentially originate from the internal heterogeneity of cationic potential, which can be realized by constraining the temperature-driven ion diffusion during solid-state reactions. Consequently, P2/O3 biphasic Na0.7Ni0.2Cu0.1Fe0.2Mn0.5O2–δ with well-designed quaternary composition is successfully obtained, exhibiting much-improved rate capabilities (62 mAh g⁻¹ at 2.4 A g⁻¹) and cycling stabilities (84% capacity retention after 500 cycles) than its single-phase analogues. Furthermore, synchrotron-based diffraction and X-ray absorption spectroscopy are employed to unravel the underlying sodium-storage mechanism of the P2/O3 biphasic structure. This work presents new insights toward the rational design of advanced layered cathodes for sodium-ion batteries.
Na ⁺ ion intercalated layered metal oxides have tremendous applications as the cathode materials for SIBs owing to their superior electrochemical performance compared to other types of cathode materials.
The layered transition‐metal‐oxide materials are one type of promising cathode materials for sodium‐ion batteries, which typically include P2, P3, and O3 phases, and each has its own advantages and challenges. Taking into account the complementarity of each single‐phase structure, constructing the composite structures is an efficient pathway to stabilize the structure and improve the electrochemical performance. Herein, three composite cathode materials owning the phase structures of P3/P2, P2/O3, and P3/P2/O3 are prepared by changing the calcinating conditions without introducing any doping element. Among them, the composite of P3/P2/O3 shows the best capacity retention of 80 mAh g–1 after 200 cycles and the highest rate performance of 100 mAh g–1 at a current density of 750 mA g–1. The improved electrochemical performance can be attributed to the staggered arrangement of different phase structures and the gradient Na‐extraction/intercalation voltages of different phases. The slip of the transition metal layer is subjected to the constraint of the adjacent phase structure, thus inhibiting the phase transformation for capacity fading. This work provides an easy way for the preparation of composite cathode structures and brings a clear case for understanding the advantage of composite structures on electrochemical performance. Undoped bi‐phase and tri‐phase cathode materials for sodium‐ion batteries are prepared to investigate the exclusive contributions of the multi‐phase structure on electrochemical performance, in which, the tri‐phase cathode show better performance than the bi‐phase cathode and then single‐phase cathode, owing to a structural constraint effect during Na+‐extraction/intercalation and the resulting restricted phase transformations.
Biphasic hybridization of layered cathode materials for sodium-ion batteries (SIBs) is crucial to enhance storage performances. The synergistic effect of biphases is generally considered to underlie the enhancement, yet the in-depth mechanism underneath remains unclear, in particular at high-voltages (> 4.2 V, vs Na⁺/Na). Herein, a unique high-voltage-stable P2/O3 composite layered oxide-Na0.85Ni0.34Mn0.33Ti0.33O2 with a specific proportion (P2:O3 = 24.8%:75.2%) is reported via tuning the amounts of Ti substitution in Na0.85Ni0.34Mn0.66-xTixO2. Operando X-ray diffraction reveals that the biphasic Na0.85Ni0.34Mn0.33Ti0.33O2 cathode successfully restrains the formation of O2 phase and undergoes completely reversible structural evolution of P2/O3–P2/P3–OP4/OP2 upon being charged to a high voltage of 4.4 V. Moreover, the interlocking effect between the phase boundaries is revealed to effectively mitigate the severe structural strain and large lattice volume change, thus further raising its structural stability under the high-voltage regions. Consequently, the obtained biphasic P2/O3-Na0.85Ni0.34Mn0.33Ti0.33O2 cathode exhibits an excellent capacity retention of 80.6% at 1C after 200 cycles. More importantly, the full cell fabricated with hard carbon anode achieves a high energy density of 294.6 Wh kg⁻¹. These results highlight the excellent electrochemical performance of biphasic cathode materials and also grasp new insight into designing composite structure materials for SIBs.
Multiphase layered transition metal oxides (LTMOs) for sodium ion battery (SIB) positive electrodes with phase interfaces across multiple length scales are a promising avenue toward practical, high‐performance SIBs. Combinations of phases can complement each other's strengths and mitigate their weaknesses if their interfaces are carefully controlled. Intra‐ and interparticle phase interactions from nanoscale to macroscale must be carefully tuned to generate distinct effects on properties and performance. An informed design strategy must be paired with relevant synthesis techniques and complemented by spatially resolved characterization tools to manipulate different length scales and interfaces. This review examines the design, synthesis, and characterization strategies that have been demonstrated for the preparation of heterogeneous, multiphasic LTMOs with phase interfaces across varied length scales.
Sodium ion batteries have become one of the research hotspots in the field of energy storage. Due to the comprehensive advantages in specific capacity, working voltage, and cost, layered oxides...
Although carbon materials have great potential for potassium ion battery (KIB) anodes due to their structural stability and abundant carbon-containing resources, the limited K+-intercalated capacity impedes their extensive applications in energy storage devices. Current research studies focus on improving the surface-induced capacitive behavior to boost the potassium storage capacity of carbon materials. Herein, we designed edge-nitrogen (pyridinic-N and pyrrolic-N) doped carbon spheres with a hierarchically porous structure to achieve high potassium storage properties. The electrochemical tests confirmed that the edge-nitrogen induced active sites were conducive for the adsorption of K+, and the hierarchical porous structure promoted the generation of stable solid electrolyte interphase (SEI) films, both of which endow the resulting materials with a high reversible capacity of 381.7 mA h g-1 at 0.1 A g-1 over 200 cycles and an excellent rate capability of 178.2 mA h g-1 at 5 A g-1. Even at 5 A g-1, the long-term cycling stability of 5000 cycles was achieved with a reversible capacity of 190.1 mA h g-1. This work contributes to deeply understand the role of the synergistic effect of edge-nitrogen induced active sites and the hierarchical porous structure in the potassium storage performances of carbon materials.
As a powerful tool for chemical compositional analyses, electron energy loss spectroscopy (EELS) can reveal an abundance of information regarding the atomic‐level electron state in a variety of materials, including the elemental types as well as their valence and concentration distributions, and the structure‐related atom radial distribution. Benefiting from its unique capabilities and the newly developed advanced transmission electron microscope (TEM) configurations (i.e., in situ bias, in situ heating, cryo‐TEM, etc.), EELS has facilitated the battery studies in various aspects. Here, a brief introduction of EELS is provided. Thereafter, a description of the recent progress in studying battery materials using EELS is provided, and finally a look ahead on the future development of EELS techniques and their applications in battery studies is provided. Electron energy loss spectroscopy (EELS) can reveal an abundance of material chemical information, which has promoted battery research in various aspects. A brief EELS introduction is provided here, and then some recent progress in studying the battery materials using EELS is summarized. Finally, a perspective on future battery studies using EELS is described.
Developing advanced cathode materials is still a great interest for sodium-ion batteries. Acceptable commercialization of sodium-ion batteries relies on the design and exploitation of suitable electrode materials. This study offers a novel insight of material design into exploiting high performance P2-type cathode materials for sodium-ion batteries. Skillfully incorporating Mg2+ into some intrinsic Na+ vacancies in Na-ion layers can achieve high-performance P2-type cathode materials for sodium-ion batteries. The materials prepared by co-precipitation approach show well-defined morphology of secondary football-like hierarchical structures. Neutron power diffraction and refinement results demonstrate the incorporation of Mg2+ into intrinsic vacancies can enlarge the space for Na-ion diffusion, can increase the d-spacing of (002) peak and the size of slabs, but reduces the chemical bond length, thus resulting in an enhanced rate capability and cycling stability. The incorporation of Mg2+ into available vacancies and such unique morphology make Na0.7Mg0.05Mn0.8Ni0.1Co0.1O2 the promising cathode, which even can be charged and discharged at ultra-high current density of 2000mA g-1 with a great specific capacity of 60mAh g-1. The work provides a new insight to design electrode materials for sodium-ion batteries.
Sodium-ion batteries (SIBs) have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. O3-type layered oxides have been considered as one of the most promising cathodes for SIBs. However, they commonly show inevitable complicated phase transitions and sluggish kinetics, incurring rapid capacity decline and poor rate capability. Here, a series of sodium-sufficient O3-type NaNi0.5Mn0.5- x Ti x O2 (0 ≤ x ≤ 0.5) cathodes for SIBs is reported and the mechanisms behind their excellent electrochemical performance are studied in comparison to those of their respective end-members. The combined analysis of in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, and scanning transmission electron microscopy for NaNi0.5Mn0.2Ti0.3O2 reveals that the O3-type phase transforms reversibly into a P3-type phase upon Na+ deintercalation/intercalation. The substitution of Ti for Mn enlarges interslab distance and could restrain the unfavorable and irreversible multiphase transformation in the high voltage regions that is usually observed in O3-type NaNi0.5Mn0.5O2, resulting in improved Na cell performance. This integration of macroscale and atomicscale engineering strategy might open up the modulation of the chemical and physical properties in layered oxides and grasp new insight into the optimal design of high-performance cathode materials for SIBs.
Room-temperature sodium-ion batteries (SIBs) have shown great promise in grid-scale energy storage, portable electronics, and electric vehicles because of the abundance of low-cost sodium. Sodium-based layered oxides with a P2-type layered framework have been considered as one of the most promising cathode materials for SIBs. However, they suffer from the undesired P2-O2 phase transition, which leads to rapid capacity decay and limited reversible capacities. Herein, we show that this problem can be significantly mitigated by substituting some of the nickel ions with magnesium to obtain Na0.67 Mn0.67 Ni0.33-x Mgx O2 (0≤x≤0.33). Both the reversible capacity and the capacity retention of the P2-type cathode material were remarkably improved as the P2-O2 phase transition was thus suppressed during cycling. This strategy might also be applicable to the modulation of the physical and chemical properties of layered oxides and provides new insight into the rational design of high-capacity and highly stable cathode materials for SIBs.
We investigated the transport properties and interfacial kinetics of P2-Na2/3[Ni1/3Ti2/3]O2 (NT) and P2-Na2/3[Ni1/3Mn1/3Ti1/3]O2 (NMT) layered oxide materials, using three techniques: DC conductivity measurement, potentiostatic intermittent titration technique, and impedance spectroscopy. The measured electronic conductivity (NT: 3.96 × 10-8 S/cm, NMT: 1.21 × 10-7 S/cm at 110?C) was orders of magnitude lower than the ionic conductivity (NT: 4.89 × 10-3 S/cm, NMT: 8.28 × 10-3 S/cm at 110?C) in both materials.Manganese addition improved the charge carrier transport properties by a factor of 2-3. The potential-dependent diffusion coefficients of both materials were in the order of 10-14-10-12 cm2/s. The charge transfer resistance was also found to have a strong potential dependency and the interfacial kinetics of NMT were considerably faster than NT. Due to its faster ionic/electronic transport in the pristine/intercalated states and faster interfacial kinetics, NMT was found to exhibit better rate performance than NT. Further performance improvements need to focus on boasting the intrinsic electronic conductivity of these materials.
Na3V2(PO4)3 (denoted as NVP) has been considered as a promising cathode material for room temperature sodium ion batteries. Nevertheless, NVP suffers from poor rate capability resulting from the low electronic conductivity. Here, the feasibility to approach high rate capability by designing carbon-coated NVP nanoparticles confined into highly ordered mesoporous carbon CMK-3 matrix (NVP@C@CMK-3) is reported. The NVP@C@CMK-3 is prepared by a simple nanocasting technique. The electrode exhibits superior rate capability and ultralong cyclability (78 mA h g−1 at 5 C after 2000 cycles) compared to carbon-coated NVP and pure NVP cathode. The improved electrochemical performance is attributed to double carbon coating design that combines a variety of advantages: very short diffusion length of Na+/e− in NVP, easy access of electrolyte, and short transport path of Na+ through carbon toward the NVP nanoparticle, high conductivity transport of electrons through the 3D interconnected channels of carbon host. The optimum design of the core–shell nanostructures with double carbon coating permits fast kinetics for both transported Na+ ions and electrons, enabling high-power performance.
Room-temperature stationary sodium-ion batteries have attracted great attention particularly in large-scale electric energy storage applications for renewable energy and smart grid because of the huge abundant sodium resources and low cost. In this article, a variety of electrode materials including cathodes and anodes as well as electrolytes for room-temperature stationary sodium-ion batteries are briefly reviewed. We compare the difference in storage behavior between Na and Li in their analogous electrodes and summarize the sodium storage mechanisms in the available electrode materials. This review also includes some new results from our group and our thoughts on developing new materials. Some perspectives and directions on designing better materials for practical applications are pointed out based on knowledge from the literature and our experience. Through this extensive literature review, the search for suitable electrode and electrolyte materials for stationary sodium-ion batteries is still challenging. However, after intensive research efforts, we believe that low-cost, long-life and room-temperature sodium-ion batteries would be promising for applications in large-scale energy storage system in the near future.
Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles. However, the growing concern on scarcity and large-scale applications of lithium resources have steered effort to realize sustainable sodium-ion batteries, Na and Fe being abundant and low-cost charge carrier and redox centre, respectively. However, their performance is limited owing to low operating voltage and sluggish kinetics. Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe(3+)/Fe(2+) redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics. Rare-metal-free Na-ion rechargeable battery system compatible with the present Li-ion battery is now in realistic scope without sacrificing high energy density and high power, and paves way for discovery of new earth-abundant sustainable cathodes for large-scale batteries.
Energy production and storage have become key issues concerning our welfare in daily life. Present challenges for batteries are twofold. In the first place, the increasing demand for powering systems of portable electronic devices and zero-emission vehicles stimulates research towards high energy and high voltage systems. In the second place, low cost batteries are required in order to advance towards smart electric grids that integrate discontinuous energy flow from renewable sources, optimizing the performance of clean energy sources. Na-ion batteries can be the key for the second point, because of the huge availability of sodium, its low price and the similarity of both Li and Nainsertion chemistries. In spite of the lower energy density and voltage of Na-ion based technologies, they can be focused on applications where the weight and footprint requirement is less drastic, such as electrical grid storage. Much work has to be done in the field of Na-ion in order to catch up with Li-ion technology. Cathodic and anodic materials must be optimized, and new electrolytes will be the key point for Na-ion success. This review will gather the up-to-date knowledge about Na-ion battery materials, with the aim of providing a wide view of the systems that have already been explored and a starting point for the new research on this battery technology.
To evaluate the potential of Na-ion batteries, we contrast in this work the difference between Na-ion and Li-ion based intercalation chemistries in terms of three key battery properties—voltage, phase stability and diffusion barriers. The compounds investigated comprise the layered AMO2 and AMS2 structures, the olivine and maricite AMPO4 structures, and the NASICONA3V2(PO4)3 structures. The calculated Na voltages for the compounds investigated are 0.18–0.57 V lower than that of the corresponding Li voltages, in agreement with previous experimental data. We believe the observed lower voltages for Na compounds are predominantly a cathodic effect related to the much smaller energy gain from inserting Na into the host structure compared to inserting Li. We also found a relatively strong dependence of battery properties on structural features. In general, the difference between the Na and Li voltage of the same structure, ΔVNa–Li, is less negative for the maricite structures preferred by Na, and more negative for the olivine structures preferred by Li. The layered compounds have the most negative ΔVNa–Li. In terms of phase stability, we found that open structures, such as the layered and NASICON structures, that are better able to accommodate the larger Na+ ion generally have both Na and Li versions of the same compound. For the close-packed AMPO4 structures, our results show that Na generally prefers the maricite structure, while Li prefers the olivine structure, in agreement with previous experimental work. We also found surprising evidence that the barriers for Na+ migration can potentially be lower than that for Li+ migration in the layered structures. Overall, our findings indicate that Na-ion systems can be competitive with Li-ion systems.
The layered Mn-based oxides (Na
x
MnO2), which is one of the most promising cathode families for rechargeable sodium-ion batteries, have received considerable attention because of their tunable electrochemical performances and low costs. Herein, a novel P2/O3 intergrown Li-containing Na0.8Li0.27Mn0.68Ti0.05O2 cathode material prepared by Ti-substitution into Mn-site is reported. Benefiting from the synergistic effects of the biphasic composite structure and inactive d0 element substitution, this P2/O3 electrode exhibits high initial charge/discharge capacity and excellent cycling performance. The combination of different characterization techniques including solid-state NMR, electron paramagnetic resonance, X-ray adsorption spectroscopy, and high-resolution transmission electron microscopy gives insights into the local electronic environment, the redox chemistry, and also the microstructure rigidity of these cathode materials upon cycling. On the basis of comprehensive comparison with the Ti-free P2/O3-Na0.8Li0.27Mn0.73O2, the observed improvement on the electrochemical performance is primarily attributed to the mitigation of notorious Mn3+/Mn4+ redox and the enhanced stability of the oxygen charge compensation behavior. From the viewpoint of structure evolution, Ti-substitution restrains the Li+ loss and irreversible structural degradation during cycling. This study provides an in-depth understanding of the electronic and crystal structure evolutions after inactive d0 element substitution and may shed light on the rational design of high-performance P2/O3 biphasic Mn-based layered cathodes.
A critical challenge for the practical use of the layered O3-type binary nickel manganese oxides for sodium-ion batteries is the poor structural stability during extended cycling. The approaches of constructing O3/P2 hybrid composites can partially improve the cycling stability, but general approaches sacrifice the advantages of high capacity and low cost of the O3-type cathodes due to excessive sodium deficiency and lithium substitution. Here, we rationally design a serial of novel O3-majority hybrid Na0.9-xNi0.45Mn0.55O2 (x = 0.02, 0.04 and 0.08) cathodes, which exhibit high capacities while maintaining exceptional long-term stability. Particularly, the optimized O3/P2 Na0.88Ni0.45Mn0.55O2 composite delivers 106.7 mA h·g⁻¹ with 71.1% capacity retention after 250 cycles at 1 C (1C = 150 mA g⁻¹), the cyclability is 32% higher than that of the O3–Na0.9Ni0.45Mn0.55O2 cathode; and it also delivers a initial discharge capacity of 75.9 mA h·g⁻¹, maintaining 72.4% capacity retention after 1000 cycles at 10 C. More importantly, the post-cycling analyses demonstrate O3/P2 hybrid phases successfully suppress the structural degradation of Na0.9Ni0.45Mn0.55O2 during battery operation. This study provides new perspectives in designing high performance cathodes for sodium-ion batteries.
Elements doping has been used to improve the electrochemical performances of O3-type layered transition metal oxide cathodes for sodium-ion batteries. But their roles and the improvement mechanism have not been clearly understood. Herein, the effects of Mg substitution for Mn on the structure and electrochemical performances of NaMn0.48Ni0.2Fe0.3Mg0.02O2 have been comprehensively investigated and some new insights into the roles of Mg in improving the rate capability and cycling stability have been presented. 1) The substitution of Mg for Mn enlarges the interlayer spacing, which not only enhances Na+ diffusion and the rate capability but also alleviates the lattice strains induced by Na+ intercalation/deintercalation. 2) the substitution of Mg for Mn also shrinks TM-O bond and TMO2 slabs which enhances the layered structure stability. 3) Mg substitution also mitigates the structure distortion or volume change of the crystal lattices and suppresses the irreversible phase transitions. 4) the substitution of low valence Mg2+ for Mn3+ reduces Mn3+ and minimizes Jahn–Teller effect, which also further alleviates the irreversible phase transformations and improves the layered structure stability. This study not only unveils the roles of Mg but also presents some insights into designing the cathode materials with both high rate capability and high cycling stability through the lattice structure regulation.
Sodium layered oxide materials show excellent performance as cathodes in sodium ion batteries, leading to considerable interest in routes to improving their properties. A manganese-rich P2/O3-phase Na2/3Li0.18Mn0.8Fe0.2O2 material is synthesized, from earth abundant precursors, via a solid state-reaction. Its biphasic nature is confirmed by X-ray diffraction and transmission electron microscopy, and the inclusion of Li by solid state NMR. The pristine electrode delivers a capacity of 125 and 105 mAh g⁻¹ at C/10 and 1C rates, respectively, with a coulombic efficiency of ca. 95 to 99.9% over 100 cycles. In addition, the influence of mechanical post-treatment is explored and shows an increased energy density and capacity retention over 50 cycles when compared to the pristine compound. The strategies outlined in this work not only apply to popular sodium manganese-based layered oxides, but also to the wider family of sodium layered oxide cathode materials in general - providing an additional facile and exploitable route to optimization.
Cathode materials are critical to the energy density, power density and safety of sodium-ion batteries (SIBs). Herein, we performed a comprehensive study to elucidate and exemplify the interplay mechanism between phase structures, interfacial microstrain and electrochemical properties of layered-structured NaxNi1/3Co1/3Mn1/3O2 cathode materials for high voltage SIBs. The electrochemical test results showed that the NaxNi1/3Co1/3Mn1/3O2 with intergrowth P2/O3/O1 structure demonstrates better electrochemical performance and better thermal stability than the NaxNi1/3Co1/3Mn1/3O2 with P2/O3 binary-phase integration and the NaxNi1/3Co1/3Mn1/3O2 with only P phase is dominate. This result is caused by the distinct interfacial microstrain development during the synthesis and cycling of P2/O3/O1 phase. In operando high energy X-ray diffraction further revealed that the intergrowth P2/O1/O3 cathode can inhibit the irreversible P2-O2 phase transformation and simultaneously improve the structure stability of the O3 and O1 phases during cycling. We believe that interfacial microstrain can serve as an indispensable bridge to guide future design and synthesis of high performance SIBs cathode materials and other high energy battery materials.
Currently, there is increasing interest in developing ‘beyond lithium’ battery technologies to augment, or in certain situations replace, lithium ion batteries (LIBs). Room temperature sodium ion batteries (NIBs) offer an attractive combination of low cost and plentiful constituents and a wide range of phases, structures and stoichiometries available for optimisation. Sodium layered oxides are considered to be promising candidates as cathode materials, due to their flexibility and versatility, as well as their intrinsically fast structural diffusion of Na ions which leads to enhanced rate capability. In particular, sodium manganese based layered oxides (generally NaxMn1−y−zMyTMzO2, where TM represents one or more transition metals, and M consists of one or more non-transition metals) are a key family of materials, in part due to the relatively low cost and environmentally friendly nature of the manganese, and consequently are worthy of a detailed investigation. Examination of these systems, particularly in terms of stoichiometry and phase, has shown that significant advances have been made recently, both in terms of understanding the mechanisms behind electrochemical performance, and in terms of refining these to produce improved materials. The goal of this review is to present the current developments in sodium manganese based layered oxides (particularly with respect to electrochemical performance, physical properties and manganese content), to discuss the current state of this field of research and to draw conclusions regarding where future investigations may be most fruitfully directed.
Sodium-ion full cell with hard carbon as anode and a layered oxide cathode based on earth abundant elements i.e., Na0.67[Fe0.5Mn0.5]O2 is reported. The irreversible capacity of the negative electrode in the full cell configuration is compensated by the addition of a sacrificial salt such as NaN3 to the P2-Na0.67[Fe0.5Mn0.5]O2 cathode material. 60% increase in the reversible capacity is achieved with the addition of 10% of sodium azide in the composite cathode without compromise on the cycle life. Though, there is a limit in its use because of the capacity fade which can be observed with the further increase in NaN3 content. The quantification of sodium ions at the end of discharge (at 1 V) after 40 cycles by ex-situ X-ray diffraction and solid state nuclear magnetic resonance supports the electrochemical data. Scanning electron microscopy shows the effect of NaN3 on the electrode microstructure in terms of the porosity created by NaN3 decomposition.
Na0.67-xKxMn0.72Ni0.14Co0.14O2 (x = 0, 0.01, 0.03, 0.05) layered cathodes were prepared as the cathode of sodium-ion batteries by a co-precipitation method. The effects of K⁺ doping were investigated, as the doping amount of K⁺ could change the structure and finally influence the electrochemical performances. The appropriate content of K⁺ could expand the Na⁺ diffusion channel and improve both the cycleability and rate performance. The Na0.66K0.01Mn0.72Ni0.14Co0.14O2 composite showed enhanced cycle performance with an initial capacity of 141 mAh g⁻¹ and 112 mAh g⁻¹ maintained after 100 cycles at 2.0C rate. Meanwhile, the pristine Na0.67Mn0.72Ni0.14Co0.14O2 (without K⁺ doping) showed a lower initial capacity of 112 mAh g⁻¹ with 67 mAh g⁻¹ retained after 100 cycles at 2.0C. What’s more, the Na0.66K0.01Mn0.72Ni0.14Co0.14O2 sample delivered a high reversible capacity of 88.4 mAh g⁻¹ even at 8.0C, which was much higher than that of Na0.67Mn0.72Ni0.14Co0.14O2 (35 mAh g⁻¹). These results demonstrated that the K⁺ doping could be a feasible strategy to enhance the performance of layered cathode for sodium ion battery.
The NaFe0.95V0.05PO4/C composite is synthesized by electrochemical ion displacement from LiFe0.95V0.05PO4/C composite in aqueous NaNO3 solution. A coulombic capacity amounting to ∼105 and ∼82 mAh g−1 at sodiation/desodiation rate of 500 and 5000 mAg−1, respectively, is evidenced. For the sake of comparison the same investigations is performed with LiFe0.95V0.05PO4/C composite in LiNO3 solution, and better capacity retention and rate performance is evidenced for NaFe0.95V0.05PO4/C one. This advancement is found to be due a higher participation of pseudocapacity in the sodiation/desodiation charge storage process. An aqueous battery composed of NaFe0.95V0.05PO4/C cathode, belt-like Na1.2V3O8 anode and NaNO3 solution as an electrolyte, tested galvanostatically, displays long-life performance with only 10% of capacity fade after 1000 charge/discharge cycles.
Room-temperature sodium-ion batteries (SIBs) have shown great promise in grid-scale energy storage, portable electronics, and electric vehicles because of the abundance of low-cost sodium. Sodium-based layered oxides with a P2-type layered framework have been considered as one of the most promising cathode materials for SIBs. However, they suffer from the undesired P2?O2 phase transition, which leads to rapid capacity decay and limited reversible capacities. Herein, we show that this problem can be significantly mitigated by substituting some of the nickel ions with magnesium to obtain Na0.67Mn0.67Ni0.33?xMgxO2 (0?x?0.33). Both the reversible capacity and the capacity retention of the P2-type cathode material were remarkably improved as the P2?O2 phase transition was thus suppressed during cycling. This strategy might also be applicable to the modulation of the physical and chemical properties of layered oxides and provides new insight into the rational design of high-capacity and highly stable cathode materials for SIBs.
The effects of Li substitution for Ti on the structure and electrochemical performances of Co-free Na0.67Mn0.55Ni0.25Ti0.2–xLixO2 (x = 0, 0.1, 0.2) layered cathode materials for sodium ion batteries have been comprehensively investigated. X-ray diffraction and Rietveld refinement results demonstrate that Li mainly occupies TM (TM = transition metal) sites in the crystal structure to maintain the P2 structure majority and a small amount of Li atoms enter Na sites to generate some O3 phase. The discharge voltage, reversible capacity, rate capability, cycling performance, and Coulombic efficiency all have been improved by Li substitution, which can be largely attributed to the integration of P2 and O3. Li substitution also raises the average discharge voltage from 2.6 to 3.1 V. Na0.67Mn0.55Ni0.25Li0.2O2 (L02) can deliver an initial capacity of about 158 mA h g–1 at 0.05C (12 mA g–1) in comparison with the Li-free sample (147 mA h g–1). Even at the high rates of 480 (2C), 1200 (5C), and 1920 (8C) mA g–1, L02 can also display ca. 93, 65, and 38 mA h g–1 discharge capacities, respectively. The rate capability is higher than what is reported in the previous Li-substituted cathode materials. In addition, Li substitution in transition-metal sites generates more defects to maintain the charge neutrality, which enhances the electronic conductivity and also has a positive effect on the Na ion diffusion coefficient. The electronic conductivity and Na ion diffusion coefficient have been enhanced by 122% and 29%, respectively, with the substitution of Li for Ti. Our results also show that the oxidation peaks become sharper with increasing Li content, which indicates the feasibility of Na ion intercalation/deintercalation in the integrated P2/O3 phase. This study also offers some new insights into designing high-performance cathode materials for sodium ion batteries.
The Na0.6Li0.6[Mn0.72Ni0.18Co0.10]O2 with well crystallized and high specific capacity is prepared by doping of Na and Li for Li and Na ion battery. The Na0.6Li0.6[Mn0.72Ni0.18Co0.10]O2 composite is easily synthesized by molten-salt method. The effects of annealing temperature, time, Na contents, and electrochemical performance are investigated. In XRD analysis, the substitution of Na-ion resulted in the P2–Na2/3MO2 structure (Na0.70MO2.05), which co-exists in the Na0.6Li0.6[Mn0.72Ni0.18Co0.10]O2 composites. The discharge capacities of cathode materials exhibited 284 mAh g−1 for Li and 237 mAh g−1 for Na ion battery with higher initial coulombic efficiency.
The title material is synthesized by solid state reaction of Na2CO3, Mn2O5, and TiO2 (Ar, 900 °C, 20 h).
While sodium-ion batteries (SIBs) are considered as a next-generation energy storage device because of the higher abundance and lower cost of sodium compared to those of lithium, developing high-power and stable cathode materials remains a great challenge. Here, micron-sized plate-like copper-substituted layered P2-type Na0.67CuxMn1-xO2 is demonstrated to rapidly charge and discharge within 5 minutes while giving a capacity of more than 90 mA h g-1, corresponding to a half-cell energy density of 260 W h (kg cathode)-1 at a power density of 3000 W (kg cathode)-1, which is comparable to that of high-power lithium-ion cathodes. The materials show excellent stability, retaining more than 70% of the initial capacity after 500 cycles at 1000 mA g-1. The good cycle and rate performances of the materials are attributed to copper in the lattice, which stabilizes the crystal structure, increases the average discharge potential and improves sodium transport. This makes Na0.67CuxMn1-xO2 an ideal choice as a cathode for high-power sodium-ion batteries.
In this work we report Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 layered cathode materials that were synthesized via a coprecipitation method. The Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 electrode exhibited an exceptionally high capacity (180.1 mA h g–1 at 0.1 C-rate) as well as excellent capacity retentions (0.2 C-rate: 89.6%, 0.5 C-rate: 92.1%) and rate capabilities at various C-rates (0.1 C-rate: 180.1 mA h g–1, 1 C-rate: 130.9 mA h g–1, 5 C-rate: 96.2 mA h g–1), which were achieved due to the Li supporting structural stabilization by introduction into the transition metal layer. By contrast, the electrode performance of the lithium-free Na[Ni0.25Fe0.25Mn0.5]O2 cathode was inferior because of structural disintegration presumably resulting from Fe3+ migration from the transition metal layer to the Na layer during cycling. The long-term cycling using a full cell consisting of a Na[Li0.05(Ni0.25Fe0.25Mn0.5)0.95]O2 cathode was coupled with a hard carbon anode which exhibited promising cycling data including a 76% capacity retention over 200 cycles.
An alluaudite-type sodium iron sulfate has recently been discovered as a 3.8 V cathode material for low-cost, high-power, and efficient sodium-ion batteries. To optimize the composition of the alluaudite phase and to explore further compounds, we have carefully surveyed the Na2SO4-FeSO4 binary system. Solid-state reactions at a moderate temperature of 623 K produce two stable phases: 1) vanthoffite-structured Na6Fe(SO4)4 and 2) alluaudite-type Na2+2xFe2−x(SO4)3 with a certain non-stoichiometry. The possible compositional and structural flexibilities demonstrated in this work inspire further improvement of the alluaudite-type sodium metal sulfates for advanced sodium-ion batteries.
A layered composite with P2 and O3 integration is proposed toward a sodium-ion battery with high energy density and long cycle life. The integration of P2 and O3 structures in this layered oxide is clearly characterized by XRD refinement, SAED and HAADF and ABF-STEM at atomic resolution. The biphase synergy in this layered P2+O3 composite is well established during the electrochemical reaction. This layered composite can deliver a high reversible capacity with the largest energy density of 640 mAh g(-1) , and it also presents good capacity retention over 150 times of sodium extraction and insertion.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The electrochemical extraction and insertion of Na in P2-Na 2/3 ][Ni 1/3 Mn 2/3 ]O 2 was studied by in situ X-ray diffraction. All the original Na can be extracted from P2-Na 2/3 ][Ni 1/3 Mn 2/3 ]O 2 and it can he reversibly inserted again. When x > 1/3 in Na x [Ni 1/3 Mn 2/3 ]O 2 . the compound remains in the P2 structure. For x 1/3, a small amount of 02-type stacking faults are introduced into the structure. When x < 1/3, the electrode exists as two coexisting phases. These are P2-Na 1/3 [Ni 1/3 Mn 2/3 ]O 2 (with some 02-type stacking faults) and [Ni 1/3 Mn 2/3 ]O 2 . [Ni 1/3 Mn 2/3 ]O 2 adopts the 02 structure with stacking faults. As sodium is reinserted in [Ni 1/3 Mn 2/3 ]O 2 to make Na 1/3 [Ni 1/3 Mn 2/3 ]O 2 the P2 structure forms again. The evolution of the lattice parameters of P2-Na x [Ni 1/3 Mn 2/3 ]O 2 (1/3 < x < 2/3) with x and the lattice constants of [Ni 1/3 Mn 2/3 ]O 2 are also reported.
Sodium-ion batteries (SIBs) are establishing themselves as a low-cost alternative to the widespread lithium-ion technology, a trend that is exemplified by the use of aluminium as anode current collector. In order to be in line with this philosophy, environmentally friendly, abundant and cheap materials need to be used in order to provide a complementary rather than competing battery technology other than lithium-ion. With the same scope in mind, herein we present the structural and electrochemical characterization of P2-type NaxMg0.11Mn0.89O2 material to demonstrate the effectiveness of Mg-doping for the development of future layered cathode materials. Of particular interest is the effect on the long-term cyclability (200 cycles), which has not been reported, yet. As shown in the manuscript, a Mg content as low as 11% in the MO2 layer leads to a smoothing of the potential profile, very high coulombic efficiencies exceeding 99.5% at 12 mA g−1 and a stable long-term cycling behaviour.
Novel layered P2/O3 intergrowth Na1-xLixNi0.5Mn0.5O2 cathodes show high-rate performance for sodium-ion batteries. The good electrochemical properties are attributed to the synergistic effect of an intergrowth structure that results from the direct incorporation of Li in the matrix. This finding highlights the importance of multiphase intergrowths with orientation relationships that can attain performance for future optimized sodium-ion batteries.
The synthesis of a new layered cathodematerial,Na0.5[Ni0.23Fe0.13Mn0.63]O2,
and its characterization in terms of crystalline structure and electrochemical performance
in a sodium cell is reported. X-ray diffraction studies and high resolution scanning electron
microscopy images reveal a well-defined P2-type layered structure, while the electrochemical tests demonstrate excellent characteristics in terms of high capacity and cycle life. This performance, the low cost, and the environmental compatibility of its component poses Na0.5[Ni0.23Fe0.13Mn0.63]O2 to be among the most promising materials for the next generation of sodium-ion batteries.
A novel tunnel Na0.61Ti0.48Mn0.52O2 material is explored as a cathode for sodium-ion batteries for the first time. It can deliver a reversible discharge capacity of 86 mA h g(-1) with an average voltage of 2.9 V at 0.2 C rate in a sodium half cell, exhibiting good rate capability and capacity retention at a cut-off voltage of 1.5-4 V. These results indicate that tunnel Na0.61Ti0.48Mn0.52O2 has a great potential application in large scale energy storage.
New electrode materials of layered oxides, Na2/3Ni1/3Mn2/3-xTixO2 (0 ≤ x ≤ 2/3), are successfully synthesized, and their electrochemical performance is examined in aprotic Na cells. A Na//Na2/3Ni1/3Mn1/2Ti1/6O2 cell delivers 127 mA h g(-1) of reversible capacity and the average voltage reaches 3.7 V at first discharge with good capacity retention.
Several new ternary oxides have been isolated in the
manganese-oxygen-sodium system for {Na}/{Mn} ⩽ 1 : Na
0.20MnO 2, Na 0.40MnO 2, Na
0.44MnO 2, Na 0.70MnO 2+ y
(0 ⩽ y ⩽ 0.25) and NaMnO 2, both with two allotropic
varieties. All structures are characterized by edge sharing (MnO
6) octahedra, forming double or triple chains for small
sodium content and bidimensional layers when the {Na}/{Mn} ratio becomes
close to 1. Electrical and magnetic behaviour of the phases has been
determined.
The Earth-abundant high capacity Na2/3[Fe1/2Mn1/2]O2 sodium-ion battery cathode material has been synthesized by conventional solid state synthesis. X-ray diffraction measurement shows the formation of the single phase Na2/3[Fe1/2Mn1/2]O2. Scanning electron microscopy shows particle size in the micron range having hexagonal morphology with high aspect ratio. To circumvent the first cycle irreversible capacity loss in Na2/3[Fe1/2Mn1/2]O2, NaN3 has been used as a source of extra Na ions added to the cathode mix. While pristine P2 type Na2/3[Fe1/2Mn1/2]O2 exhibits an irreversible capacity of 59 mAh/g, it reduces to 27 mAh/g after adding 5 wt.% NaN3 with concomitant nitrogen evolution in the half cell configuration. With further optimization, the combination of Na2/3[Fe1/2Mn1/2]O2 with NaN3 is promising for a viable sodium-ion cell.
The status of ambient temperature sodium ion batteries is reviewed in light of recent developments in anode, electrolyte and cathode materials. These devices, although early in their stage of development, are promising for large-scale grid storage applications due to the abundance and very low cost of sodium-containing precursors used to make the components. The engineering knowledge developed recently for highly successful Li ion batteries can be leveraged to ensure rapid progress in this area, although different electrode materials and electrolytes will be required for dual intercalation systems based on sodium. In particular, new anode materials need to be identified, since the graphite anode, commonly used in lithium systems, does not intercalate sodium to any appreciable extent. A wider array of choices is available for cathodes, including high performance layered transition metal oxides and polyanionic compounds. Recent developments in electrodes are encouraging, but a great deal of research is necessary, particularly in new electrolytes, and the understanding of the SEI films. The engineering modeling calculations of Na-ion battery energy density indicate that 210 Wh kg−1 in gravimetric energy is possible for Na-ion batteries compared to existing Li-ion technology if a cathode capacity of 200 mAh g−1 and a 500 mAh g−1 anode can be discovered with an average cell potential of 3.3 V.
Na-ion batteries were tested with layered Na(Ni1/3Fe1/3Mn1/3)O2 cathodes and carbon anodes in a sodium-salt containing organic ester carbonate electrolyte. Layered single phase Na(Ni1/3Fe1/3Mn1/3)O2 was synthesized from solid-state reaction using a (Ni1/3Fe1/3Mn1/3)C2O4 oxalate precursor and Na2CO3 fired at 850 °C with slow-cooling. The Na-ion NayC/Na1 − y(Ni1/3Fe1/3Mn1/3)O2 cell had an average voltage of ~ 2.75 V, modest capacity of 100 mA h g− 1 for 150 cycles (1.5–4.0 V), and a capacity of 94 mA h g− 1 at a 1 °C rate. X-ray diffraction (XRD) data of extracted cycled electrodes were used to characterize material stability and phases formed upon cycling. It was found that Na1 − y(Ni1/3Fe1/3Mn1/3)O2 (0 ≤ y ≤ 0.46) maintains a layered structure with good crystallinity over 150 cycles. These results bode well for the development and optimization of rechargeable Na-ion batteries.
Lithium metal phosphates (olivines) are emerging as long-lived, safe cathode materials in Li-ion batteries. Nano-LiFePO4 already appears in high-power applications, and LiMnPO4 development is underway. Current and emerging Fe- and Mn-based intercalants, however, are low-energy producers compared to Ni and Co compounds. LiNiPO4, a high voltage olivine, has the potential for superior energy output (>10.7 Wh in 18650 batteries), compared with commercial Li(Co,Ni)O2 derivatives (up to 9.9 Wh). Speculative Co and Ni olivine cathode materials charged to above 4.5 V will require significant advances in electrolyte compositions and nanotechnology before commercialization. The major drivers toward 5 V battery chemistries are the inherent abuse tolerance of phosphates and the economic benefit of LiNiPO4: it can produce 34% greater energy per dollar of cell material cost than LiAl0.05Co0.15Ni0.8O2, today's “standard” cathode intercalant in Li-ion batteries.
RECHARGEABLE lithium batteries can store more than twice as much energy
per unit weight and volume as other rechargeable
batteries1,2. They contain lithium ions in an electrolyte,
which shuttle back and forth between, and are intercalated by, the
electrode materials. The first commercially successful rechargeable
lithium battery3, introduced by the Sony Corporation in 1990,
consists of a carbon-based negative electrode, layered LiCoO2
as the positive electrode, and a non-aqueous liquid electrolyte. The
high cost and toxicity of cobalt compounds, however, has prompted a
search for alternative materials that intercalate lithium ions. One such
is LiMn2O4, which has been much studied as a
positive electrode material4-7 the cost of manganese is less
than 1% of that of cobalt, and it is less toxic. Here we report the
synthesis and electrochemical performance of a new material, layered
LiMnO2, which is structurally analogous to LiCoO2.
The charge capacity of LiMnO2 (~270mAhg-1)
compares well with that of both LiCoO2 and
LiMn2O4, and preliminary results indicate good
stability over repeated charge-discharge cycles.
In recent years consistent attention has been devoted to novel types of lithium rechargeable batteries in which the metal
anode is replaced by a lithium‐source anode. The general interest in these batteries, often called rocking‐chair batteries,
has increased consistently; however, the idea of exploiting the rocking lithium systems for achieving improvements in safety
and cycle life is not new, but dates back to the beginning of the eighties. In this paper we critically review the progress
in this area and discuss the impact that rocking chair systems may have on the future of lithium battery technology.
A layered phase, NaNi1/3Mn1/3Co1/3O2 (NaNMC), isostructural to NaCoO2 has been synthesized. Stoichiometric NaNMC crystallizes in a rhombohedral R (3) over barm space group where Na is in an octahedral environment (O3-Type). Galvanostatic cycling on NaNMC vs Na cell indicated a reversible intercalation of 0.5 Na, leading to a capacity of 120 mAh.g(-1) in the voltage range of 2-3.75 V and indicating its possible application in Na-ion batteries. The electrochemically driven Na insertion/deinsertion in NaNMC is associated with several phase transitions and solid solution regimes which are studied by in situ X-ray diffraction. Sodium deinsertion in NaxNMC resulted in sequential phase transitions composed of biphasic and monophasic domains. The composition driven structural evolution in NaxNMC follows the sequence O3 double right arrow O1 double right arrow P3 double right arrow P1 phases with an increased 'c' parameter, while the 'a' parameter remains almost unchanged.
A series of spinel-structured LiMn2−x−yNixCryO4 have been prepared and their electrochemical performances as 5-V cathode materials for lithium ion batteries are evaluated. The synthesis reactions for these materials are characterized by TG/DSC, XRD and SEM. TG/DSC measurements show that the chemical reactions for the final product are completed below 400 °C. XRD analysis indicates that spinel structure is formed at around 650 °C. However, SEM images show well-defined polyhedron crystalline particles do not appear until 800 °C. Electrochemical evaluation shows that LiMn1.4Ni0.4Cr0.2O4 prepared at 850 °C boasts the best electrochemical performance with an initial discharge capacity of 128 mA h/g and a capacity retention of more than 90% after 230 cycles between 3.5 and 4.98 V.
Rechargeable lithium batteries have risen to prominence as key devices for green and sustainable energy development. Electric vehicles, which are not equipped with an internal combustion engine, have been launched in the market. Manganese- and iron-based positive-electrode materials, such as LiMn(2)O(4) and LiFePO(4), are used in large-scale batteries for electric vehicles. Manganese and iron are abundant elements in the Earth's crust, but lithium is not. In contrast to lithium, sodium is an attractive charge carrier on the basis of elemental abundance. Recently, some layered materials, where sodium can be electrochemically and reversibly extracted/inserted, have been reported. However, their reversible capacity is typically limited to 100 mAh g(-1). Herein, we report a new electrode material, P2-Na(2/3)[Fe(1/2)Mn(1/2)]O(2), that delivers 190 mAh g(-1) of reversible capacity in the sodium cells with the electrochemically active Fe(3+)/Fe(4+) redox. These results will contribute to the development of rechargeable batteries from the earth-abundant elements operable at room temperature.
- Z Lu
- J R Dahn
Z. Lu and J. R. Dahn, In Situ X-Ray Diffraction Study of P2-Na 2/3 [Ni 1/3 Mn 2/3 ]O 2, J. Electrochem. Soc., 2001, 148, A1225.
95 ]O 2 Cathode for Sodium Ion Batteries
- S.-M Oh
- S.-T Myung
- J.-Y Hwang
- B Scrosati
- K Amine
- Y.-K Sun
S.-M. Oh, S.-T. Myung, J.-Y. Hwang, B. Scrosati, K. Amine and
Y.-K.
Sun,
High
Capacity
O3-Type
Na
[Li 0.05 (Ni 0.25 Fe 0.25 Mn 0.5 ) 0.95 ]O 2 Cathode for Sodium Ion
Batteries, Chem. Mater., 2014, 26, 6165-6171.
High Performance Na 0.5 [Ni 0.23 Fe 0.13 Mn 0.63 ]O 2 Cathode for Sodium-Ion Batteries
- I Hasa
- D Buchholz
- S Passerini
- B Scrosati
- J Hassoun
I. Hasa, D. Buchholz, S. Passerini, B. Scrosati and
J. Hassoun, High Performance Na 0.5 [Ni 0.23 Fe 0.13 Mn 0.63 ]O 2
Cathode for Sodium-Ion Batteries, Adv. Energy Mater.,
2014, 4, 1400083.