Search

Potassium‐ion batteries (PIBs) have attracted significant research interest in the context of driving the advancement of grid energy storage due to K's elemental abundance and high theoretical output voltage. The main challenge facing PIBs is to find suitable cathode materials with fast transport kinetics and stable framework structures to intercalate/de‐intercalate the large‐size K+. Among these candidates, transition‐metal layered oxides are have excellent potential and have been extensively exploited due to their stable skeleton structure, simple synthetic chemistry, and high working potential. Herein, the current research status and prospects of layered transition‐metal oxide cathodes are summarized, especially focussing on the fine structure optimization engineering and energy storage mechanism. In addition, a brief overview of the research on advanced characterization techniques for PIBs is introduced in detail. Finally, the main research directions and hot spots of new‐type transition‐metal layered oxide cathode are also predicted, in order to guide the future development of advanced PIBs. [ABSTRACT FROM AUTHOR]

Rechargeable aluminum ion batteries (AIBs) are one of the most promising battery technologies for future large‐scale energy storage due to their high theoretical volumetric capacity, low‐cost, and high safety. However, the low capacity of the intercalation‐type cathode materials reduces the competitiveness of AIBs in practical applications. Herein, a conversion‐type FeF3‐expanded graphite (EG) composite is synthesized as a novel cathode material for AIBs with good conductivity and cycle stability. Combined with the introduction of a single‐wall carbon nanotube modified separator, the shuttle effect of the intermediate product, FeCl2, is significantly restrained. Moreover, enhanced coulombic efficiency and reversible capacity are achieved. The AIB exhibits a satisfying reversible specific capacity of 266 mAh g−1 at 60 mA g−1 after 200 cycles, and good Coulombic efficiency of nearly 100% after 400 cycles at a current density of 100 mA g−1. Ex situ X‐ray diffraction and X‐ray photoelectron spectroscopy are applied to explore the energy storage mechanism of FeF3 in AIBs. The results reveal that the intercalation of Al3+ species and the reduction of Fe3+ species occurrs in the discharge process. These findings are meaningful for the fundamental understanding of the FeF3 cathode for AIBs and provide unprecedented insight into novel conversion type cathode materials for AIBs. [ABSTRACT FROM AUTHOR]

Even though lithium ion batteries (LIBs) have seen extensive applications during the past 20 years, the anode materials which have realized commercialization are mainly restricted to graphite and Li4Ti5O12. However, because of the limited capacity of these two intercalation‐type anodes, they cannot meet the higher requirements in energy density of some applications. Very few types of high‐capacity anode materials have been successfully commercialized, mainly due to the inevitable large volume change during lithium insertion/extraction. Herein, a promising anode material, CaV4O9, which shows both high gravimetric capacity of more than 600 mAh g–1 with a safe average discharge potential of about 0.8 V, and near‐zero volume change character like Li4Ti5O12, is identified. The specific lithium storage mechanism and the origin of near‐zero volume change character are revealed. Considering the superior performance endowed by these unique intrinsic properties, CaV4O9 shows great potential for commercialized anode material and may promote innovation in LIBs. [ABSTRACT FROM AUTHOR]

VS2 is one of the attractive layered cathodes for alkali metal‐ion batteries. However, the understanding of the detailed reaction processes and energy storage mechanism is still inadequate. Herein, the Li+/Na+/K+ insertion/extraction mechanisms of VS2 cathode are elucidated on the basis of experimental analyses and theoretical simulations. It is found that the insertion/extraction behavior of Li+ is partially irreversible, while the insertion/extraction behavior of Na+/K+ is completely reversible. The detailed intermediates and final products (Li0.33VS2, LiVS2, Na0.5VS2, NaVS2, K0.6VS2, KzVS2, z > 0.6) during the discharging/charging processes are identified, indicating that VS2 undergoes different phase transitions and solid–solution reactions in different battery systems, which have a great influence on the battery performance. Moreover, the diffusion of Na+ in VS2 cathode is demonstrated to be much slower than that of Li+ and K+. Such mechanistic research provides a reference for in‐depth understanding of energy storage in layered transition metal sulfides/selenides. [ABSTRACT FROM AUTHOR]

Sodium-ion battery has captured much attention due to the abundant sodium resources and potentially low cost. However, it suffers from poor cycling stability and low diffusion coefficient, which seriously limit its widespread application. Here, K3V2(PO4)3/C bundled nanowires are fabricated usinga facile organic acid-assisted method. With a highly stable framework, nanoporous structure, and conductive carbon coating, the K3V2(PO4)3/C bundled nanowires manifest excellent electrochemical performances in sodium-ion battery. A stable capacity of 119 mAh g−1 can be achieved at 100 mA g−1. Even at a high current density of 2000 mA g−1, 96.0% of the capacity can be retained after 2000 charge-discharge cycles. Comparing with K3V2(PO4)3/C blocks, the K3V2(PO4)3/C bundled nanowires show significantly improved cycling stability. This work provides a facile and effective approach to enhance the electrochemical performance of sodium-ion batteries. [ABSTRACT FROM AUTHOR]

With the increasing energy crisis and environmental pollution, rechargeable aqueous Zn‐based batteries (AZBs) are receiving unprecedented attention due to their list of merits, such as low cost, high safety, and nontoxicity. However, the limited voltage window, Zn dendrites, and relatively low specific capacity are still great challenges. In this work, a new reaction mechanism of reversible Mn2+ ion oxidation deposition is introduced to AZBs. The assembled Mn2+/Zn2+ hybrid battery (Mn2+/Zn2+ HB) based on a hybrid storage mechanism including Mn2+ ion deposition, Zn2+ ion insertion, and conversion reaction of MnO2 can achieve an ultrawide voltage window (0–2.3 V) and high capacity (0.96 mAh cm−2). Furthermore, the carbon nanotubes coated Zn anode is proved to effectively inhibit Zn dendrites and control side reaction, hence exhibiting an ultrastable cycling (33 times longer than bare Zn foil) without obvious polarization. Benefiting from the optimal Zn anode and highly reversible Mn2+/Zn2+ hybrid storage mechanism, the Mn2+/Zn2+ HB shows an excellent cycling performance over 11 000 cycles with a 100% capacity retention. To the best of the authors' knowledge, it is the highest reported cycling performance and wide voltage window for AZBs with mild electrolyte, which may inspire a great insight into designing high‐performance aqueous batteries. [ABSTRACT FROM AUTHOR]

Niobium pentoxides (Nb2O5) have attracted extensive interest for ultrafast lithium‐ion batteries due to their impressive rate/capacity performance and high safety as intercalation anodes. However, the intrinsic insulating properties and unrevealed mechanisms of complex phases limit their further applications. Here, a facile and efficient method is developed to construct three typical carbon‐confined Nb2O5 (TT‐Nb2O5@C, T‐Nb2O5@C, and H‐Nb2O5@C) nanoparticles via a mismatched coordination reaction during the solvothermal process and subsequent controlled heat treatment, and different phase effects are investigated on their lithium storage properties on the basis of both experimental and computational approaches. The thin carbon coating and nanoscale size can endow Nb2O5 with a high surface area, high conductivity, and short diffusion length. As a proof‐of‐concept application, when employed as LIB anode materials, the resulting T‐Nb2O5@C nanoparticles display higher rate capability and better cycling stability as compared with TT‐Nb2O5@C and H‐Nb2O5@C nanoparticles. Furthermore, a synergistic effect is investigated and demonstrated between fast diffusion pathways and stable hosts in T‐Nb2O5 for ultrafast and stable lithium storage, based on crystal structure analysis, in situ X‐ray diffraction analysis, and density functional theoretical calculations. Therefore, the proposed synthetic strategy and obtained deep insights will stimulate the development of Nb2O5 for ultrafast and long‐life LIBs. [ABSTRACT FROM AUTHOR]