It is essential to develop afacile and effective method to enhance the electrochemical performance of lithium metal anodes for building high-energy-density Li-metal based batteries.H erein, we explored the temperature-dependent Li nucleation and growth behavior and constructed ad endritefree Li metal anode by elevating temperature from room temperature (20 8 8C) to 60 8 8C. As eries of ex situ and in situ microscopyi nvestigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density,a nd compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li-ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite-free Li growth behavior.A sa nodes in both half cells and full cells,t he compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 8 8C. Figure 4. a) Coulombic efficiencies of Li plating/striping on Cu at different temperatures. b) The first cycle voltage profiles of Li plating/striping. c) Charge/ discharge voltage profiles of Li jjLi symmetric cells. d) Energy density and energy efficiency of Li jjLTOfull cells at 60 8 8Cand 20 8 8C.

Layered lithium‐rich cathode materials have attracted extensive interest owing to their high theoretical specific capacity (320–350 mA h g−1). However, poor cycling stability and sluggish reaction kinetics inhibit their practical applications. After many years of quiescence, interest in layered lithium‐rich cathode materials is expected to revive in answer to our increasing dependence on high‐energy‐density lithium‐ion batteries. Herein, we review recent research progress and in‐depth descriptions of the structure characterization and reaction mechanisms of layered lithium‐rich manganese‐based cathode materials. In particular, we comprehensively summarize the proposed reaction mechanisms of both the cationic redox reaction of transition‐metal ions and the anionic redox reaction of oxygen species. Finally, we discuss opportunities and challenges facing the future development of lithium‐rich cathode materials for next‐generation lithium‐ion batteries.

of lithium resources in the earth's crust (0.0022 wt%). [9] Therefore, it is critical to develop new battery systems. [10] Multivalent-ion batteries can in principle provide higher energy density than monovalent LIBs, which could overcome the aforementioned problems by employing a non-Li metallic anode. [11][12][13] Among various candidates, rechargeable magnesium batteries have many advantages over LIBs, such as abundant Mg resources, small ionic radius (0.72 Å) and high theoretical volumetric capacity (3833 mAh cm −3 ) (Figure 1a). Particularly, RMBs are inherently safer than LIBs because metallic Mg anodes are dendrite-free upon cycling. [14][15][16][17] In addition, Mg also possesses higher oxidative stability than lithium. [18] The configurations and working mechanisms of RMBs are similar to those of LIBs (Figure 1b,c). However, the current research on RMBs still faces many challenges. Particularly, metallic Mg anodes have a strong tendency to form an insulated and passivating surface layer, which kinetically blocks electrochemical reactions at room temperature. [19][20][21] Such passivating layers engender difficulty for choosing compatible electrodes and electrolytes. [22,23] In addition, many RMBs electrolytes are air-sensitive, highly corrosive and flammable, [24,25] which poses a threat to their practical applications. Additionally, it is challenging to quest for suitable cathode materials with the rapid intercalation/ deintercalation of Mg 2+ at room temperature, considering the complex reaction mechanism of Mg-based electrochemistry. Many useful pioneering works have been devoted to developing cathode materials for RMBs (Figure 1d). [26][27][28] The strong electrostatic interaction of Mg 2+ inevitably results in sluggish kinetics, which is kinetically slower than Li + , especially at room temperature. [19] In this review, we summarize recently developed cathode materials for rechargeable magnesium-ion batteries. The anode materials beyond Mg metal are also discussed. Furthermore, we explored other Mg-based energy storage technologies, including Mg-air batteries, Mg-sulfur batteries, and Mg-iodine batteries. This review could also provide basic knowledge and valuable strategies for the advancement of high-energy-density rechargeable magnesium-based batteries. Cathode MaterialsSimilar to LIBs, the working mechanism of RMBs batteries are based on the shuttle of Mg 2+ ions between cathode and anode Benefiting from higher volumetric capacity, environmental friendliness and metallic dendrite-free magnesium (Mg) anodes, rechargeable magnesium batteries (RMBs) are of great importance to the development of energy storage technology beyond lithium-ion batteries (LIBs). However, their practical applications are still limited by the absence of suitable electrode materials, the sluggish kinetics of Mg 2+ insertion/extraction and incompatibilities between electrodes and electrolytes. Herein, a systematic and insightful review of recent advances in RMBs, including intercalation-based cathode materials and conversion...

Potassium‐ion batteries (PIBs) are emerging as one of the potential alternatives to lithium‐ion batteries for next‐generation rechargeable battery systems. Nevertheless, the lack of suitable cathode materials with high capacity hinders their practical applications. Recently, Prussian blue analogs (PBAs) cathode materials stand out as promising candidates for PIBs. Their unique crystal structure with open 3D frameworks and large interstitial voids favors fast K+ intercalation without causing drastic volume expansion, which is the prerequisite for high‐rate and long‐term battery operation. Herein, a fundamental review on the development and advance of PBAs cathode materials is presented for PIBs with in‐depth elucidation of their crystal structures, chemical compositions, and electrochemical performances. Particularly, the unique and prominent advantages of PBAs in both aqueous and nonaqueous PIBs are highlighted. In addition, to bridge the current gap from the laboratory to future commercialization, potential improvement strategies are proposed to overcome the present drawbacks. Finally, perspectives and new insights are provided for further exploration and research in PBAs for better PIBs.

Potassium‐ion batteries are attracting great interest for emerging large‐scale energy storage owing to their advantages such as low cost and high operational voltage. However, they are still suffering from poor cycling stability and sluggish thermodynamic kinetics, which inhibits their practical applications. Herein, the synthesis of hierarchical K1.39Mn3O6 microspheres as cathode materials for potassium‐ion batteries is reported. Additionally, an effective AlF3 surface coating strategy is applied to further improve the electrochemical performance of K1.39Mn3O6 microspheres. The as‐synthesized AlF3 coated K1.39Mn3O6 microspheres show a high reversible capacity (about 110 mA h g−1 at 10 mA g−1), excellent rate capability, and cycling stability. Galvanostatic intermittent titration technique results demonstrate that the increased diffusion kinetics of potassium‐ion insertion and extraction during discharge and charge processes benefit from both the hierarchical sphere structure and surface modification. Furthermore, ex situ X‐ray diffraction measurements reveal that the irreversible structure evolution can be significantly mitigated via surface modification. This work sheds light on rational design of high‐performance cathode materials for potassium‐ion batteries.

Hard carbons with low cost and high specific capacity hold great potential as anode materials for potassium‐based energy storage. However, their sluggish reaction kinetics and inevitable volume expansion degrade their electrochemical performance. Through rational nanostructure design and a heteroatom doping strategy, herein, the synthesis of phosphorus/oxygen dual‐doped porous carbon spheres is reported, which possess expanded interlayer distances, abundant redox active sites, and oxygen‐rich defects. The as‐developed battery‐type anode material shows high discharge capacity (401 mAh g−1 at 0.1 A g−1), outstanding rate capability, and ultralong cycling stability (89.8% after 10 000 cycles). In situ Raman spectroscopy and density functional theory calculations further confirm that the formation of PC and PO/POH bonds not only improves structural stability, but also contributes to a rapid surface‐controlled potassium adsorption process. As a proof of concept, a potassium‐ion hybrid capacitor is assembled by a dual‐doped porous carbon sphere anode and an activated carbon cathode. It shows superior electrochemical performance, which opens a new avenue to innovative potassium‐based energy storage technology.

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A review focusing on the tunable pore structure design, surface chemistry, composition, and electrochemical performances of PCSs in various types of rechargeable batteries in order to provide insight and inspiration for promoting the development of next-generation high-performance batteries.