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Metal Oxides for Rechargeable Batteries Energy Applications
Abstract
Nearly three decades of significant academic and commercialization
progress, appreciations have to be credited for Li+ ion-based rechargeable secondary
batteries, which conquered the entire world. The Li+ ion batteries dictate the
consumer battery market and are considered crucial for the practical realization of
plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and
electric vehicles (EVs). Recently, post-lithium–ion batteries, particularly Na, K,
Mg, and Zn, and Al–ion batteries have also been intensively explored for various
energy storage tenders due to their natural abundance, low cost, and environmental
safety of these materials. The utilization of metal oxides in battery application is
tremendous and, an example, the first commercial lithium ion batteries by Sony
Co. with LiCoO2 as a cathode. Recently, Ni-rich layered oxide-based lithium ion
batteries are on an edge of commercialization. The focus on battery research had
increased drastically from 2010, and still metal oxide-based cathodes/anodes are
researched exclusively due to their significant physicochemical properties. This
chapter emphasizes electrochemical properties of various metal oxide-based electrode
materials for various secondary rechargeable energy storage applications
including sodium ion batteries (SIBs), potassium ion batteries (PIBs), and zinc ion
batteries (ZIBs).
Prussian blue analogs (PBAs) could be used as Faradic electrodes materials in capacitive deionization (CDI) to desalinate seawater or brackish water, because it had the unique open framework that not only enables Na⁺ with large ion radius to be reversibly embedded/exited during charging/discharging, but also had a large channel structure to the transmission of Na⁺. However, due to the disadvantages of easy agglomeration, poor conductivity and easy structural collapse, the further applications of PBAs had been seriously limited. To break these limitations, the 3D composite material [email protected] was successfully synthesized by simple coprecipitation method through dotting NaFeHCF nanoparticles on the staggered carbon nanotube network. As expected, the NaFeHCF particles were uniformly embedded in the CNT networks without any agglomeration resulting in higher specific surface area and utilization. Due to the doping of carbon nanotubes, [email protected] enhanced charge transfer and ion diffusion, resulting in low charge transfer resistance and good wettability, thus benefiting CDI performance. In the desalination performance test, the [email protected] electrode could achieve a high desalination capacity of 82.97 mg g⁻¹ and a low energy consumption of 2.78 kg NaCl kWh⁻¹ in 3000 mg L⁻¹ NaCl, and the desalination capacity could still reach 89.82% of the initial value after 50 cycles. Consequently, the [email protected] achieves high desalination performance in CDI systems.
Sodium-ion batteries are considered to be the most promising alternative to lithium-ion batteries for large-scale stationary energy storage applications due to the abundant sodium resource in the Earth' crust and as a result, relatively low cost. Sodium layered transition metal oxides (Na
x
TMO2) are proper Na-ion cathode materials because of low cost and high theoretical capacity. Currently most researchers focus on the improvement of electrochemical performance such as high rate capability and long cycling stability. However, for Na
x
TMO2, the structure stability against humid atmosphere is essentially important since most of them are instable in air, which is not favorable for practical application. Here we provide a comprehensive review of recent progresses on air-stable Na
x
TMO2 oxides. Several effective strategies are discussed, and further investigations on the air-stable cathodes are prospected.
Potassium-ion batteries (PIBs) have attracted tremendous attention due to their low cost, fast ionic conductivity in electrolyte, and high operating voltage. Research on PIBs is still in its infancy, however, and achieving a general understanding of the drawbacks of each component and proposing research strategies for overcoming these problems are crucial for the exploration of suitable electrode materials/electrolytes and the establishment of electrode/cell assembly technologies for further development of PIBs. In this review, we summarize our current understanding in this field, classify and highlight the design strategies for addressing the key issues in the research on PIBs, and propose possible pathways for the future development of PIBs toward practical applications. The strategies and perspectives summarized in this review aim to provide practical guidance for an increasing number of researchers to explore next-generation and high-performance PIBs, and the methodology may also be applicable to developing other energy storage systems.
The development of lithium-ion batteries (LIBs) is hindered by the limited lithium resources and their uneven geographical distribution. Novel rechargeable batteries based on abundant elements (e.g., Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Al ³⁺ ) show great promising alternatives to LIBs. However, several challenges still remain for these emerging batteries, such as sluggish kinetics, poor reversibility, lack of suitable electrode materials, etc., induced by large radius and/or high charge density of primary ions. Among various strategies to address these challenges, multi-ion strategies show great feasibility to enhance the electrochemical performance of these emerging rechargeable battery systems. These multi-ion strategies involve electrochemistry of multiple ions in different electrode materials and electrolytes, and are devoted to combining individual merits of multiple ions as primary ions in rechargeable batteries. So far, several multi-ion strategies have been proposed, including dual-ion, triple-ion, and quadruple-ion strategies. It is demonstrated that such strategies, not only are beneficial to enhance diffusion kinetics and cycling reversibility, and/or to increase working voltage, but also provide more options of electrode materials for these emerging rechargeable batteries. In this review, we outline the challenges involved in these emerging rechargeable batteries. The fundamental configurations and corresponding reaction mechanisms of multi-ion strategies are tangibly discussed. Then, special focuses are on the applications of multi-ion strategies in merging rechargeable batteries, in which we elaborate and discuss in detail the enhanced effect of multi-ion strategies on electrochemical performance. Finally, the state-of-the-art challenges and the future directions of multi-ion strategies are highlighted and discussed.
LiNiO₂ (LNO) has been introduced as cathode active material (CAM) for Li‐ion batteries in 1990. After years of intensive research, it emerged that several instability issues plague the material, so that it was abandoned in favor of isostructural metal‐substituted compounds called NCA (for lithium nickel cobalt aluminum oxide) and NCM (lithium nickel cobalt manganese oxide). These sacrifice a certain amount of specific energy in exchange for stability, durability and safety. With few exceptions, NCA and NCM are nowadays the industrial standard when it comes to automotive applications; however, the continuous push towards electric cars with longer driving range is synonym, for these compounds, with increasing the nickel content (which is already beyond 80%), eventually leading back again to LiNiO₂. For this reason we provide here a comprehensive review of the material, almost 30 years after its introduction as CAM. We aim at highlighting its physicochemical peculiarities, which make LNO complex in every aspect. We specifically stress the effect of the Li off‐stoichiometry (Li1‐zNi1+zO2) on every property of LNO, especially the electrochemical ones. We then focus on the key instability issues that plague the compound and on the strategies implemented so far to overcome them. Finally, in the course of the review we point to open questions that still remain to be addressed by the scientific community, and to which research directions seem more promising to lead LNO to its full exploitation.
Lithium cobalt oxide, as a popular cathode in portable devices, delivers only half of its theoretical capacity in commercial lithium-ion batteries. When increasing the cut-off voltage to release more capacity, solubilization of cobalt in the electrolyte and structural disorders of lithium cobalt oxide particles are severe, leading to rapid capacity fading and limited cycle life. Here, we show a class of ternary lithium, aluminum, fluorine-modified lithium cobalt oxide with a stable and conductive layer using a facile and scalable hydrothermal-assisted, hybrid surface treatment. Such surface treatment hinders direct contact between liquid electrolytes and lithium cobalt oxide particles, which reduces the loss of active cobalt. It also forms a thin doping layer that consists of a lithium-aluminum-cobalt-oxide-fluorine solid solution, which suppresses the phase transition of lithium cobalt oxide when operated at voltages >4.55 V.
The concept of a self-generated coating on LiCoO 2 that does not require any additional cost-consuming coating precursors has been proposed by a combination of simple processes, water washing and heat-treatment. Surface impurities, such as carbonate and hydroxide, on the LiCoO 2 surface are finely controlled during the self-generated coating process. The coating improves the electrochemical performance when both washing and heat-treatment are used, whereas each individual process is not effective. The surface changes of LiCoO 2 are analyzed to elucidate the mechanism of the self-generated coating using X-ray photoelectron spectroscopy, FT-IR spectroscopy, X-ray diffraction, and electron microscopies. The thickness of the coating layer and the type of the coating materials are controlled by the temperature of the heat-treatment after the washing process. When a high temperature of 700°C is used for the heat-treatment, a heavy coating layer having several tens of nm thickness is generated on the LiCoO 2 powder that severely interferes with the migration of Li ions and the electron conduction, thereby degrading cycle performance. On the other hand, the samples annealed at a low temperatures of 400°C has a thin coating layer with thickness of 10∼30 nm that improves the cycleability by inhibiting the electrolyte decomposition.
Ni-rich transition metal layered oxide materials are of great interest as positive electrode materials for lithium ion batteries. As the popular electrode materials NMC (LiNi1-x-yMnxCoyO2) and NCA (LiNi1-x-yCoxAlyO2) become more and more Ni-rich, they approach LiNiO2. Therefore it is important to benchmark the structure and electrochemistry of state of the art LixNiO2 for the convenience of researchers in the field. In this work, LiNiO2 synthesized from a commercial Ni(OH)2 precursor and modern synthesis methods shows a specific capacity close to the theoretical specific capacity of 274 mAh/g. In-situ X-ray diffraction (XRD) measurements were conducted to obtain accurate structural information versus lithium content, x. The known multiple phase transitions of LixNiO2 during charge and discharge were clearly observed, and the variation in unit cell lattice constants and volume was measured. Differential capacity versus voltage (dQ/dV vs. V) studies were used to investigate the electrochemical properties including regions of composition that show very slow kinetics. It is hoped that this work will be a useful reference for those working on Ni-rich positive electrode materials for Li-ion cells.
Rechargeable potassium-ion batteries have been gaining traction as not only promising low-cost alternatives to lithium-ion technology, but also as high-voltage energy storage systems. However, their development and sustainability are plagued by the lack of suitable electrode materials capable of allowing the reversible insertion of the large potassium ions. Here, exploration of the database for potassium-based materials has led us to discover potassium ion conducting layered honeycomb frameworks. They show the capability of reversible insertion of potassium ions at high voltages (~4 V for K2Ni2TeO6) in stable ionic liquids based on potassium bis(trifluorosulfonyl) imide, and exhibit remarkable ionic conductivities e.g. ~0.01 mS cm-1 at 298 K and ~40 mS cm-1 at 573 K for K2Mg2TeO6. In addition to enlisting fast potassium ion conductors that can be utilised as solid electrolytes, these layered honeycomb frameworks deliver the highest voltages amongst layered cathodes, becoming prime candidates for the advancement of high-energy density potassium-ion batteries.
Layered oxides are promising cathode materials for sodium-ion batteries because of their high theoretical capacities. However, many of these layered materials experience severe capacity decay when operated at high voltage (>4.25 V), hindering their practical application. It is essential to design high-voltage layered cathodes with improved stability for high-energy-density operation. Herein, nano P2-Na2/3(Mn0.54Ni0.13Co0.13)O2 (NCM) materials are synthesized using a modified Pechini method as a prospective high-voltage sodium storage component without any modification. The changes in the local ionic state around Ni, Mn, and Co ions with respect to the calcination temperature are recorded using X-ray absorption fine structure analysis. Among the electrodes, NCM fired at 850 °C (NCM-850) exhibits excellent electrochemical properties with an initial capacity and energy density of 148 mAh g–1 and 555 Wh kg–1, respectively, when cycled between 2 and 4.5 V at 160 mA g–1 along with improved cyclic stability after 100 charge/discharge cycles. In addition, the NCM-850 electrode is capable of maintaining a 75 mAh g–1 capacity even at a current density of 3200 mA g–1. In contrast, the cell fabricated with NCM obtained at 800 °C shows continuous capacity fading because of the formation of an impurity phase during the synthesis process. The obtained capacity, rate performance, and energy density along with prolonged cyclic life for the cell fabricated with the NCM-850 electrodes are some of the best reported values for sodium-ion batteries as compared to those of other p2-type sodium intercalating materials.
Spinel based transition metal oxide - FeV2O4 is applied as a novel anode for sodium-ion battery. The electrochemical tests indicate that FeV2O4 is generally controlled by pseudo-capacitive process. Using cost-effective and eco-friendly aqueous based binders, Sodium-Carboxymethylcellulose/Styrene butadiene rubber, a highly stable capacity of ~97 mAh∙g-1 is obtained after 200 cycles. This is attributed to the strong hydrogen bonding of carboxyl and hydroxyl groups indicating superior binding with the active material and current collector which is confirmed by the ex-situ cross-section images of the electrode. Meanwhile, only ~27 mAh∙g-1 is provided by the electrode using poly(vinylidene difluoride) due to severe detachment of the electrode material from the Cu foil after 200 cycles. The obtained results provide an insight into the possible applications of FeV2O4 as an anode material and the use of water-based binders to obtain highly stable electrochemical tests for sodium-ion battery.
Nonaqueous potassium ion batteries (KIBs) are one of the emerging electrochemical energy storage technologies due to the abundance of potassium resources, but the difficulties of intercalation of large size K‐ions into electrode materials hinder the development of KIBs. Here, a layered potassium vanadate K0.5V2O5 is proposed as a potential cathode material for KIBs. Despite the large size of K‐ions, the as‐fabricated material is capable of delivering a reversible capacity around 90 mAh g−1 at 10 mA g−1 in the voltage range of 1.5–3.8 V (vs K+/K), and also exhibits a fast rate capability with a capacity of 60 mAh g−1 at 200 mA g−1 and good cycling stability with 81% capacity retention after 250 cycles at 100 mA g−1. Ex situ X‐ray diffraction and X‐ray photoelectron spectroscopy reveal that the layered potassium vanadate exhibits a highly stable and reversible structure change with a transition between V4+ and V5+ upon potassiation/depotassiation. Additionally, galvanostatic intermittent titration technique results show that the kinetics of potassiation/depotassiation is mainly determined by K‐ion diffusion in the active material. The present study may open up further exploration of potassium vanadates and other layered transition metal oxides in the field of KIBs. A layered potassium vanadate K0.5V2O5 is reported as a cathode material for non‐aqueous potassium ion batteries. This material demonstrates good cycling stability and a transition between V4+ and V5+ takes place upon potassiation/depotassiation. This study may stimulate further exploration of potassium vanadates and other layered transition metal oxides in the field of potassium ion batteries.
Owing to their safety and low cost, aqueous rechargeable Zn-ion batteries (ARZIBs) are currently more feasible for grid-scale applications, as compared to their alkali-counterparts such as lithium and sodium ion batteries (LIBs, SIBs), for both aqueous and non-aqueous systems. However, the materials used in ARZIBs have a poor rate capability and inadequate cycle lifespan, serving as a major handicap for long-term storage applications. Here, we report vanadium-based Na2V6O16·3H2O nanorods employed as a positive electrode for ARZIBs, which display superior electrochemical Zn storage properties. A reversible Zn2+ ion (de)intercalation reaction describing the storage mechanism is revealed using in situ synchrotron X-ray diffraction technique. This cathode material delivers a very high rate capability and high capacity retention of more than 80% over 1,000 cycles, at a current rate of 40C (1C = 361 mA g−1). The battery offers a specific energy of 90 W·h kg−1 at a specific power of 15.8 KW kg−1 , enlightening the material advantages for an eco-friendly atmosphere.
The use of transition-metal vanadium oxides (TMVOs) for the production of safe and low-cost aqueous rechargeable zinc-ion batteries (ARZIBs) has not been fully explored in detail so far. The electrochemistry involved in multistep Zn2+ insertion/de-insertion induced by vanadium reduction/oxidation in layered α-Zn2V2O7 upon cycling has been interpreted. It exhibits an excellent specific energy of 166 Wh kg−1 and high capacity holding of 85% after 1,000 cycles at an ultra-high current drain of 4000 mA g−1.
Although recent efforts have expanded the stability window of aqueous electrolytes from 1.23 V to >3 V, intrinsically safe aqueous batteries still deliver lower energy densities (200 Wh/kg) compared with state of-the-art Li-ion batteries (~400 Wh/kg). The essential origin for this gap comes from their cathodic stability limit, excluding the use of the most ideal anode materials (graphite, Li metal). Here, we resolved this ‘‘cathodic challenge’’ by adopting an ‘‘inhomogeneous additive’’ approach, in which a fluorinated additive immiscible with aqueous electrolyte can be applied on anode surfaces as an interphase precursor coating. The strong hydrophobicity of the precursor minimizes the competitive water reduction during interphase formation, while its own reductive decomposition forms a unique composite interphase consisting of both organic and inorganic fluorides. Such effective protection allows these high-capacity/low-potential anode materials to couple with different cathode materials, leading to 4.0 V aqueous Li-ion batteries with high efficiency and reversibility.
Narrow electrochemical stability window (1.23 V) of aqueous electrolytes is always considered the key obstacle preventing aqueous sodium-ion chemistry of practical energy density and cycle life. The sodium-ion water-in-salt electrolyte (NaWiSE) eliminates this barrier by offering a 2.5 V window through suppressing hydrogen evolution on anode with the formation of a Na+-conducting solid-electrolyte interphase (SEI) and reducing the overall electrochemical activity of water on cathode. A full aqueous Na-ion battery constructed on Na0.66[Mn0.66Ti0.34]O2 as cathode and NaTi2(PO4)3 as anode exhibits superior performance at both low and high rates, as exemplified
by extraordinarily high Coulombic efficiency (>99.2%) at a low rate (0.2 C)
for >350 cycles, and excellent cycling stability with negligible capacity losses
(0.006% per cycle) at a high rate (1 C) for >1200 cycles. Molecular modeling
reveals some key differences between Li-ion and Na-ion WiSE, and identifies a
more pronounced ion aggregation with frequent contacts between the sodium
cation and fluorine of anion in the latter as one main factor responsible for the
formation of a dense SEI at lower salt concentration than its Li cousin.
As promising high-capacity cathode materials for Na-ion batteries, O3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Herein, a combined structure modulation is proposed to concurrently tackle the two handicaps via reducing Na layers spacing and simultaneously increasing valance state of transition metals. Guided by density functional theory calculations, we demonstrate that such a modulation can be subtly realized through co-substitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure of NaNi0.5Mn0.5O2 via Cu/Ti co-doping. The as-obtained NaNi0.45Cu0.05Mn0.4Ti0.1O2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its original structure and capacity after being soaked in water. Such a simple and effective structure modulation reveals a new avenue for developing high-performance O3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forwards.
K-ion batteries are a potentially exciting and new energy storage technology that can combine high specific energy, cycle life, and good power capability, all while using abundant potassium resources. The discovery of novel cathodes is a critical step toward realizing K-ion batteries (KIBs). In this work, a layered P2-type K0.6CoO2 cathode is developed and highly reversible K ion intercalation is demonstrated. In situ X-ray diffraction combined with electrochemical titration reveals that P2-type K0.6CoO2 can store and release a considerable amount of K ions via a topotactic reaction. Despite the large amount of phase transitions as function of K content, the cathode operates highly reversibly and with good rate capability. The practical feasibility of KIBs is further demonstrated by constructing full cells with a graphite anode. This work highlights the potential of KIBs as viable alternatives for Li-ion and Na-ion batteries and provides new insights and directions for the development of next-generation energy storage systems.
Energy production and storage technologies have attracted a great deal of attention for day-to-day applications. In recent decades, advances in lithium-ion battery (LIB) technology have improved living conditions around the globe. LIBs are used in most mobile electronic devices as well as in zero-emission electronic vehicles. However, there are increasing concerns regarding load leveling of renewable energy sources and the smart grid as well as the sustainability of lithium sources due to their limited availability and consequent expected price increase. Therefore, whether LIBs alone can satisfy the rising demand for small- and/or mid-to-large-format energy storage applications remains unclear. To mitigate these issues, recent research has focused on alternative energy storage systems. Sodium-ion batteries (SIBs) are considered as the best candidate power sources because sodium is widely available and exhibits similar chemistry to that of LIBs; therefore, SIBs are promising next-generation alternatives. Recently, sodiated layer transition metal oxides, phosphates and organic compounds have been introduced as cathode materials for SIBs. Simultaneously, recent developments have been facilitated by the use of select carbonaceous materials, transition metal oxides (or sulfides), and intermetallic and organic compounds as anodes for SIBs. Apart from electrode materials, suitable electrolytes, additives, and binders are equally important for the development of practical SIBs. Despite developments in electrode materials and other components, there remain several challenges, including cell design and electrode balancing, in the application of sodium ion cells. In this article, we summarize and discuss current research on materials and propose future directions for SIBs. This will provide important insights into scientific and practical issues in the development of SIBs.
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.
The rapidly expanding field of nonaqueous multi-valent intercalation batteries offers a promising way to overcome safety, cost, and energy density limitations of state-of-the-art Li-ion battery technology. We present a critical and rigorous analysis of the increasing volume of multivalent battery research, focusing on a wide range of intercalation cathode materials and the mechanisms of multivalent ion insertion and migration within those frameworks. The present analysis covers a wide variety of material chemistries, including chalcogenides, oxides, and polyanions, highlighting merits and challenges of each class of materials as multivalent cathodes. The review underscores the overlap of experiments and theory, ranging from charting the design metrics useful for developing the next generation of MV-cathodes to targeted in-depth studies rationalizing complex experimental results. On the basis of our critical review of the literature, we provide suggestions for future multivalent cathode studies, including a strong emphasis on the unambiguous characterization of the intercalation mechanisms.
A zero-strain insertion material of Li 2 Ni 0.2 Co 1.8 O 4 having a spinel framework was synthesized and showed very small dimensional change during charge–discharge reaction with large volumetric capacity.
A 5.5 V high-voltage electrolyte enables both Li-metal and graphite anodes and 5.3 V LiCoMnO 4 cathodes to achieve a high Coulombic efficiency of >99%, opening new opportunity to develop high-energy Li-ion batteries. The design principle for the high voltage and safe electrolytes will greatly benefit the development of next-generation electrochemical energy storage devices. These findings should therefore be of extensive interest to a broad audience working on energy storage technologies, materials, and electrochemistry in general.
Due to the abundant resources and potential price advantage, potassium-ion batteries (KIBs) have recently drawn increasing attention as a promising alternative to lithium-ion batteries (LIBs) for their applications in electrochemical energy storage applications. Despite of the continuous progress in identifying possible electrode materials, the development of KIBs has been challenged by different problems including low reversible capacities, unsatisfactory cycling stability, and insufficient energy density, which become serious concerns for the practical application of KIBs. In this review, we will summarize the recent advancements on both cathode and anode materials with focus on their structural-performance relationship. Meanwhile, challenges and opportunities related to the future development of KIBs are also discussed.
Lithium-ion batteries with high energy density, long cycle life, and appropriate safety levels are necessary to facilitate the penetration of electrified transportation systems into the automobile market. Currently, Ni-rich layered Li[Ni1-2xCoxMnx]O2 (NCM, x ≤ 0.2) cathodes show high capability for increasing the energy densities of cells. However, the poor thermal stability of this type of cathodes is retarding their commercialization. In this study, it is demonstrated that operating Ni-rich cathodes at higher cut-off potentials (> 4.3 V) rather than progressing to highly nickel enriched compositions can be a better method of enhancing their energy densities and maintaining adequate thermal stability. It is shown that a Li[Ni0.6Co0.2Mn0.2]O2 (NCM-622) cathode cycled up to 4.5 V exhibits a discharge capacity of 200 mAh g-1 and capacity retention of 93 %, which are similar to the ones of Li[Ni0.8Co0.1Mn0.1]O2 (NCM-811) cycled up to 4.3 V. Similar volume change during cycling and comparable NiO-like rocksalt impurity layer after 100 cycles in both of the cathodes may be the reason for their similar cycle lives despite operating at different charge cut-off potentials. In spite of the comparable capacity and retention, NCM-622 cathode exhibits superior thermal stability, in which the occurrence of the exothermic reaction is delayed by 50 °C, than NCM-811. In addition, analogous trends are observed in the cathodes with higher nickel compositions, i.e., NCM-811 and Li[Ni0.9Co0.05Mn0.05]O2 cycled up to 4.5 V and 4.3 V, respectively.
The development of high-rate cathodes particularly with remarkable wide-temperature-tolerance sodium-storage capability plays a significant role in commercial applications of sodium-ion batteries (SIBs). Herein, we devise a scaled-up electrospinning avenue to fabricate nanocrystal-constructed ultralong layered NaCrO2 nanowires (NWs) towards SIBs as a wide-temperature-operating cathode. The resultant one-dimensional (1D) NaCrO2 nano-architecture is endowed with orientated and shortened electronic/ionic transport, and remarkable structural tolerance to stress change over sodiation-desodiation processes. Benefiting from these structural superiorities, the NaCrO2 NWs are featured with prominent Na+-storage behaviors in the wide operating temperature range from ‒15 to 55 °C. Promisingly, the NaCrO2 NWs exhibit extraordinary high-rate capacities of ~108.8 and ~87.2 mAh g-1 at 10 and 50 C rates at 25 °C, and even 94.6 (55 °C) and ~60.1 (‒15 °C) mAh g-1 at 10 C along with outstanding cyclic stabilities with capacity retentions of ~80.6% (‒15 °C), 88.4% (25 °C) and ~86.9 % (55 °C). The overall performance of our NaCrO2 is superior to other reported NaCrO2-based cathodes, even with conductive nano-carbon coating. Encouragingly, a competitive energy density of ~161 Wh kg-1 can be obtained by the NaCrO2 NWs-based full cell. Therefore, our NaCrO2 NWs can be highly anticipated as advanced cathode for commercial wide-temperature-tolerance SIBs.
Design of high voltage potassium-based cathode materials is critical to the development of high energy density potassium-ion (K-ion) battery. Herein we present a new honeycomb layered framework K2/3Ni1/3Co1/3Te1/3O2 (or equivalently as K2NiCoTeO6 and adopting a P2-type stacking mode in Hagenmuller’s nomenclature) that exhibits a high working voltage (ca. 4.3 V versus K⁺/K) by far exceeding the performance of layered cathode materials for K-ion battery reported so far. The displayed record high voltage is rooted in the more electronegative [TeO6]⁶⁻ moiety which, through the inductive effect, engenders a high voltage compared to O2²⁻. This work will pave way for the further advancement of high voltage cathode materials for rechargeable potassium-ion battery.
Undesired reactions between layered sodium transition-metal oxide cathodes and air impede their utilization in practical sodium-ion batteries. Consequently, a fundamental understanding of how layered oxide cathodes degrade in air is of paramount importance, but it has not been fully understood yet. Here a comprehensive study on a model material NaNi0.7Mn0.15Co0.15O2 reveals its reaction chemistry with air and the dynamic evolution of the degradation species upon air exposure. We find that besides the extraction of Na+ ions from the crystal lattice to form NaOH, Na2CO3, and Na2CO3•H2O in contact with air, nickel ions gradually dissolve from the bulk to form NiO and accumulate on the particle surface as revealed by sub-nanometer surface sensitive time-of-flight secondary ion mass spectroscopy. The degradation species on the surface are insulating, leading to an increase in interfacial resistance and declined electrochemical performance. We also demonstrate a feasible surface coating strategy for suppressing the unfavorable degradation process. Understanding the degradation mechanism at nanoscale can facilitate future development of high-energy cathodes for sodium-ion batteries.
Multivalent‐ion batteries built on water‐based electrolytes represent energy storage at suitable price‐points, competitive performance and enhanced safety. However, to comply with modern energy‐density requirements, the battery must be reversible within an operating voltage window greater than 1.23V or the electrochemical stability limits of free water. Taking advantage of its powerful solvation and catalytic activities, adding water in electrolyte preparations can unlock a wider gamut of liquid mixtures as compared to strictly non‐aqueous systems. However, a point‐by‐point sweep of all potential formulations is arduous and ineffective without some form of systematic rationalization. The present review consolidates recent progress, pitfalls, limits and insights critical to expediting aqueous electrolyte designs which boost multivalent‐ion battery outputs.
Increased interest in electrical energy storage is in large part driven by the explosive growth in intermittent renewable sources such as wind and solar as well as the global drive...
Due to massively growing demand arising from energy storage systems, sodium ion batteries (SIBs) have been recognized as the most attractive alternative to the current commercialized lithium ion batteries (LIBs) owing to the wide availability and accessibility of sodium. Unfortunately, the low energy density, inferior power density and poor cycle life are still the main issues for SIBs in the current drive to push the entire technology forward to meet the benchmark requirements for commercialization. Over the past few years, tremendous efforts have been devoted to improving the performance of SIBs, in terms of higher energy density and longer cycling lifespans, by optimizing the electrode structure or the electrolyte composition. In particular, among the established anode systems, those materials, such as metals/alloys, phosphorus/phosphides, and metal oxides/sulfides/selenides, that typically deliver high theoretical sodium-storage capacities have received growing interest and achieved significant progress. Although some review articles on electrodes for SIBs have been published already, many new reports on these anode materials are constantly emerging, with more promising electrochemical performance achieved via novel structural design, surface modification, electrochemical performance testing techniques, etc. So, we herein summarize the most recent developments on these high-performance anode materials for SIBs in this review. Furthermore, the different reaction mechanisms, the challenges associated with these materials, and effective approaches to enhance performance are discussed. The prospects for future high-energy anodes in SIBs are also discussed.
Due to the abundance of sodium sources and relatively high safety, sodium-ion batteries (SIBs) are considered as a promising candidate for next-generation large-scale energy storage systems. However, currently the lack of suitable anode materials is limiting the development of SIBs. Metal oxides (MOs) which have the advantage of rich material sources and high theoretical capacity have attracted lots of attention as anode for SIBs in scientific community. Nevertheless, due to the low conductivity, large volumetric change during charge/discharge process of SIBs, the material often demonstrates unsatisfactory cycling stability and capacity rate. Construction of material composites through incorporation of graphene to MOs with tailored nanostructure and composition has demonstrated promising performance in SIBs. In this review, we attempt to provide a comprehensive summary of the research development on the low-cost metal oxides/graphene composites (MOs/G) as anode materials for SIBs. The characteristics of different morphology, composition, crystal phases of MOs/G composites and their electrochemical properties in SIBs are demonstrated. The correlation of the morphological and structural properties of the MOs materials with their performance in SIBs is discussed. This timely review sheds light on the path towards achieving cost effective, safe SIBs with high energy density and long cycling life using MOs/G as anode materials.
Stoichiometric LiMnO2 and NaMnO2 with a cation-disordered rocksalt-type structure as metastable polymorphs are successfully prepared by mechanical milling. Although cation-disordered rosksalt phases with a stoichiometric composition (Li:Mn molar ratio = 1:1), are expected to be electrochemically less active, both samples show superior performance as electrode materials when compared with thermodynamically stable layered phases in Li/Na cells. Both metastable samples deliver large reversible capacities, which correspond to >80% of theoretical capacities with relatively small polarization on the basis of reversible Mn3+/Mn4+ redox. Moreover, for rocksalt LiMnO2, phase transition into a spinel phase is effectively suppressed compared with a thermodynamically stable phase. Electrode reversibility of NaMnO2 is also drastically improved by the use of the metastable phase with good capacity retention. Metastable phases with unique nanostructures open a new path to design the advanced electrode materials with high energy density, and thus broad impact is anticipated for rechargeable Li/Na battery applications.
Mesoporous orthorhombic LiMnO2 has been directly fabricated by a one-step flux method in this work. Benefiting from the unique mesoporous structure, the orthorhombic LiMnO2 prepared through calcinating the mixture of flux LiOH H2O and Mn2O3 with various Li/Mn molar ratios shows enhanced lithium storage properties. When used as the cathode for lithium ion battery, the mesoporous orthorhombic LiMnO2 has been found to exhibit a maximum discharge capacity of 191.5 mAh g⁻¹ and a high reversible capacity of 162.6 mAh g⁻¹ (84.9% retention) after 50 cycles at a current density of 0.1 C rate. These results demonstrate its potential application in high performance lithium-ion batteries.
The electrochemical storage of sodium ions from aqueous electrolytes in transition metal oxides is of interest for energy and sustainability applications. These include low-cost and safe energy storage and energy-efficient water desalination. The strong interactions between water and transition metal oxide surfaces, as well as those between water and sodium ions, dictate the stability and electrochemical energy storage mechanisms in these materials. This review summarizes the implications of water as an electrolyte solvent for transition metal oxide electrodes, and sodium ion intercalation from neutral pH electrolytes into a diverse set of transition metal oxides. Increased control of the aqueous electrolyte/transition metal oxide interface is likely to lead to improvements in stability and capacity, which are critical breakthroughs for the implementation of transition metal oxides in aqueous sodium ion energy storage technologies.
Transformational changes in battery technologies are critically needed to enable the effective use of renewable energy sources, such as solar and wind, and to allow for the expansion of the electrification of vehicles. Developing high-performance batteries is critical to meet these requirements, which certainly relies on material breakthroughs. This review article presents the recent progresses and challenges in discovery of high-performance anode materials for Li-ion batteries related to their applications in future electrical vehicles and grid energy storage. The advantages and disadvantages of a series of anode materials are highlighted.
Sodium ion batteries (NIBs) are one of the versatile technologies for low-cost rechargeable batteries. O3-type layered sodium transition metal oxides (NaMO2, M = transition metal ions) are one of the most promising positive electrode materials considering their capacity. However, the use of O3 phases is limited due to their low redox voltage and associated multiple phase transitions which are detrimental for long cycling. Herein, a simple strategy is proposed to successfully combat these issues. It consists of the introduction of a larger, nontransition metal ion Sn⁴⁺ in NaMO2 to prepare a series of NaNi0.5Mn0.5− ySn yO2 (y = 0–0.5) compositions with attractive electrochemical performances, namely for y = 0.5, which shows a single-phase transition from O3 ⇔ P3 at the very end of the oxidation process. Na-ion NaNi0.5Sn0.5O2/C coin cells are shown to deliver an average cell voltage of 3.1 V with an excellent capacity retention as compared to an average stepwise voltage of ≈2.8 V and limited capacity retention for the pure NaNi0.5Mn0.5O2 phase. This study potentially shows the way to manipulate the O3 NaMO2 for facilitating their practical use in NIBs.
Transition metal vanadates have attracted much attention for high capacity anodes of lithium ion batteries (LIBs). However, they have obvious drawbacks (short cycle-lives and low rate performance) because of the intrinsically low electronic conductivity and serious volume variation during Li-ion desorption and insertion. In particular, pure Co3V2O8 micro-pencils (pCVO MPs) have a stable and regular crystal structure, large tap density and uniform grain size, but, unfortunately, they have not exhibited expected electrochemical performance. Herein, we report the successful preparation of reduced graphene oxide coated Co3V2O8 micro-pencils (rGO@CVO MPs) through a facile approach combining hydrothermal synthesis with thermal reduction. When tested as anodes for LIBs, rGO@CVO MPs exhibit superior electrochemical performance compared to that of pure Co3V2O8 micro-pencils (pCVO MPs). The anodes of rGO@CVO MPs show a high reversible capacity of 760 mA h g⁻¹ over 200 cycles at 200 mA g⁻¹, and 500 mA h g⁻¹ can remain after 500 cycles at 1000 mA g⁻¹, with an increase in 200 mA h g⁻¹ in contrast to the pCVO MPs. It is consequently demonstrated that the composite material (rGO@CVO MPs) is a promising anode material for LIBs.
A novel layered ternary material K0.67Ni0.17Co0.17Mn0.66O2 has been fabricated via a co-precipitation assisted solid-phase method and further evaluated as a cathode for potassium-ion batteries for the first time. Highly reversible K⁺ intercalation/deintercalation is demonstrated in this material. It delivers a reversible capacity of 76.5 mAh/g with average voltage of 3.1 V and shows good cycling performance with capacity retention of 87% after 100 cycles at 20 mA/g. This work may give a new insight into developing cathode materials for potassium-ion batteries.
Novel and low-cost batteries are of considerable interest for application in large-scale energy storage systems, for which the cost per cycle becomes critical. Here, this study proposes K0.5MnO2 as a potential cathode material for K-ion batteries as an alternative to Li technology. K0.5MnO2 has a P3-type layered structure and delivers a reversible specific capacity of ≈100 mAh g−1 with good capacity retention. In situ X-ray diffraction analysis reveals that the material undergoes a reversible phase transition upon K extraction and insertion. In addition, first-principles calculations indicate that this phase transition is driven by the relative phase stability of different oxygen stackings with respect to the K content.
Zn3V2O8 (ZVO) with sheet-like morphology is synthesized by a simple green precipitation technique via a metal-organic framework (MOF) intermediate for use as an anode in high energy lithium-ion batteries (LIBs). This sheet-like morphology, enriched with highly porous features, is evident from transmission electron microscopy (TEM) and surface area measurements. When tested as a lithium half-cell electrode, the ZVO porous sheets delivered a reversible specific capacity of 1228 mA h g⁻¹ at a current density of 0.3 A g⁻¹ for 200 cycles. Interestingly, on applying two different high current densities of 1 and 3 A g⁻¹, this porous ZVO material registered high capacities of 665 and 510 mA h g⁻¹, initially for 30 and 50 cycles, respectively. On reducing the current density to 0.5 and 1 A g⁻¹ for the two instances, both sustained stable capacities of 906 and 687 mA h g⁻¹ in the 160th and 600th cycles, respectively. The fact that these porous sheets maintained a stable capacity as high as 370 mA h g⁻¹ at the high applied current density of 5 A g⁻¹ after 2000 discharge/charge cycles reveals the structural stability of the ZVO prepared by a simple green precipitation technique.
We report a study of the structural evolution of P2-Na0.67[Mn0.66Fe0.20Cu0.14]O2 positive electrode for Na-ion batteries during (NIBs) charge and discharge. Operando X-ray diffraction (XRD) analysis revealed two phase transitions over the first cycle (1.5 - 4.3 V). Ex-situ pair distribution function (PDF) analysis was used to characterize the local structure of the high voltage phase observed in many Fe-containing layered P2-struture oxide materials. The high voltage phase is disordered along the c-axis and is derived by the migration of a fraction of iron ions into the interlayer space. Operando X-ray absorption spectroscopy (XAS) was employed to monitor the local structure evolution of the transition metals, showing the existence of Mn3+/4+ redox below ~ 3.4 V, followed by the redox activity of Cu and Fe ions at higher voltages. No evident change was observed in the K-edge X-ray absorption near edge structure (XANES) of the transition metals at voltages above 4.1 V, where the growth of the high voltage phase is initiated. These results imply the reversible contribution of oxide ions in the redox process. This process results in voltage fading over cycling, similar to Li2MnO3-based positive electrode materials in Li-ion batteries.
Transition metal oxides (TMOs), based on conversion reaction, are attractive candidate anode materials for lithium-ion batteries (LIBs) because of their high theoretical capacity and safety characteristics. In this review, we will summarize recent progress on the rational design and efficient synthesis of TMOs with controlled morphologies, composition, and micro-/nanostructures, along with their Li storage behaviors. Single metal oxides of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), ruthenium (Ru), chromium (Cr), molybdenum (Mo), and tungsten (W), and their common binary metal oxides are covered in this review. Finally, the ignored merits of conversion reaction is put forward, and the design of metal oxides electrode by making full use of the merits is proposed.
P2-type layered Na2/3Ni1/4Mn3/4O2 has been synthesized by a solid-state method and its electrochemical behavior has been investigated as a potential cathode material in aqueous hybrid sodium/lithium ion electrolyte by adopting activated carbon as the counter electrode. The results indicate that the Na⁺/Li⁺ ratio in aqueous electrolyte has a strong influence on the capacity and cyclic stability of the Na2/3Ni1/4Mn3/4O2 electrode. Increase on the Li⁺ content leads to a shift of the redox potential towards a high value, which is favorable for the improvement of the working voltage of the layered material as cathode. It is found that the coexistence of Na⁺ and Li⁺ in aqueous electrolyte can improve the cyclic stability for the Na2/3Ni1/4Mn3/4O2 electrode. A reversible capacity of 54 mAh g⁻¹ was obtained with a high cyclability as the Na⁺/Li⁺ ratio was 2:2. Furthermore, an aqueous hybrid ion cell was assembled with the as-proposed Na2/3Ni1/4Mn3/4O2 as cathode and NaTi2(PO4)3/graphite synthesized in this work as anode in 1 M Na2SO4/Li2SO4 (mole ratio as 2:2) mixed electrolyte. The cell shows an average discharge voltage at 1.2 V, delivering an energy density of 36 Wh kg⁻¹ at a power density of 16 W kg⁻¹ based on the total mass of the active materials.
A spherical stoichiometric LiNiO2 particle, which was composed of compactly packed nanosized primary particles, was prepared and cycled at different cutoff voltages to explicitly demonstrate the effect of phase transitions during Li deintercalation/intercalation on the Li-ion intercalation stability of LiNiO2. The capacity retention was greatly improved by suppressing the H2 → H3 phase transition at 4.1 V, such that 95% of the initial capacity (164 mAh g–1) was retained after 100 cycles when cycled at 4.1 V. At 4.2 and 4.3 V, continuous capacity loss (81% of 191 mAh g–1 at 4.2 V and 75% of 232 mAh g–1 at 4.3 V after 100 cycles) was observed during cycling, and these electrodes incurred extensive structural damages (micro-, hairline and nanoscale cracks observed by transmission electron microscopy) from the repeated lattice contraction and expansion accompanying the H2 → H3 transition, in agreement with the cycling data.
Layered metal oxides have attracted increasing attention as cathode materials for sodium-ion batteries (SIBs). However, the application of such cathode materials is still hindered by their poor rate capability and cycling stability. Here, a facile self-templated strategy is developed to synthesize uniform P2-Na0.7 CoO2 microspheres. Due to the unique microsphere structure, the contact area of the active material with electrolyte is minimized. As expected, the P2-Na0.7 CoO2 microspheres exhibit enhanced electrochemical performance for sodium storage in terms of high reversible capacity (125 mAh g(-1) at 5 mA g(-1) ), superior rate capability and long cycle life (86 % capacity retention over 300 cycles). Importantly, the synthesis method can be easily extended to synthesize other layered metal oxide (P2-Na0.7 MnO2 and O3-NaFeO2 ) microspheres.
Large-scale electric energy storage is fundamental to the use of renewable energy. Recently, research and development efforts on room-temperature sodium-ion batteries (NIBs) have been revitalized, as NIBs are considered promising, low-cost alternatives to the current Li-ion battery technology for large-scale applications. Herein, we introduce a novel layered oxide cathode material, Na0.78Ni0.23Mn0.69O2. This new compound provides a high reversible capacity of 138 mAh g-1 and an average potential of 3.25 V vs. Na+/Na with a single smooth voltage profile. Its remarkable rate and cycling performances are attributed to the elimination of the P2-O2 phase transition upon cycling to 4.5 V. The first charge process yields an abnormally excess capacity which has yet to be observed in other P2 layered oxides. Metal K-edge XANES results show that the major charge compensation at the metal site during Na-ion deintercalation is achieved via the oxidation of nickel (Ni2+) ions, whereas, to a large extent, manganese (Mn) ions remain in their Mn4+ state. Interestingly, Electron Energy Loss Spectroscopy (EELS) and soft X-ray Absorption Spectroscopy (sXAS) results reveal differences in electronic structures in the bulk and at the surface of electrochemically-cycled particles. At the surface, transition metal ions (TM ions) are in a lower valence state than in the bulk, and the O K-edge pre-peak disappears. Based on previous reports on related Li-excess LIB cathodes, it is proposed that part of the charge compensation mechanism during the first cycle takes place at the lattice oxygen site, resulting in a surface to bulk transition metal gradient. We believe that by optimizing and controlling oxygen activity, Na layered oxide materials with higher capacities can be designed.
K-ion battery (KIB) is a new-type energy storage device which possesses potential advantages of low-cost and abundant resource of K precursor materials. However, the main challenge lies on the lack of stable materials to accommodate the intercalation of large-size K-ions. Here we designed and constructed a novel earth abundant Fe/Mn-based layered oxide interconnected nanowires as a cathode in KIBs for the first time, which exhibits both high capacity and good cycling stability. On the basis of advanced in situ X-ray diffraction (XRD) analysis and electrochemical characterization, we confirm that interconnected K0.7Fe0.5Mn0.5O2 nanowires can provide stable framework structure, fast K-ion diffusion channels and three-dimensional electron transport network during the depotassiation/potassiation processes. As a result, a considerable initial discharge capacity of 178 mAh g-1 is achieved when measured for KIBs. Besides, K-ion full batteries based on interconnected K0.7Fe0.5Mn0.5O2 nanowires/soft carbon are assembled, manifesting over 250 cycles with a capacity retention of ~76%. This work may open up the investigation of high-performance K-ion intercalated earth abundant layered cathodes and will push the development of energy storage systems.