The safety of energy storage equipment has always been a stumbling block to the development of battery, and sodium ion battery is no exception. However, as an ultimate solution, the use of non‐flammable electrolyte is susceptible to the side effects, and its poor compatibility with electrode, causing failure of batteries. Here, we report a non‐flammable electrolyte design to achieve high‐performance sodium ion battery, which resolves the dilemma via regulating the solvation structure of electrolyte by hydrogen bonds and optimizing the electrode–electrolyte interphase. The reported non‐flammable electrolyte allows stable charge‐discharge cycling of both sodium vanadium phosphate@hard carbon and Prussian blue@hard carbon full pouch cell for more than 120 cycles with a capacity retention of >85 % and high cycling Coulombic efficiency (99.7 %).

Recently, environmental degradation along with the energy crisis has led to an urgent necessity to develop renewable and clean energy storage devices. The sodium ion batteries (SIBs) have become promising candidates in the whole energy storage system, due to its rich and low‐cost sodium resources. To accelerate the commercialization of SIBs, the energy density of SIBs needs to be further improved. Increasing the operating voltage of SIBs is considered to be an effective method, which requires stable and high‐voltage cathode materials. Comparatively, polyanionic sulfate materials (PSMs) with stable skeletons, adjustable structures, operational safety, and the high electronegativity of SO42− are believed to be the most promising high‐energy‐cathodes. In this review, recent progresses on several typical sulfates for SIBs are summarized. What's more, based on their intrinsic characteristics, the structures and kinetic behaviors of PSMs are also discussed. Reported measures to optimize their electrochemical performances and structural stability are summarized and reviewed. The key challenges and corresponding opportunities for PSMs are also discussed. The insights presented in this review may be a guide for designing and developing stable and practical PSMs for room‐temperature SIBs, which is conducive to promoting their industrialization.

Hard carbon (HC) anodes have shown extraordinary promise for sodium‐ion batteries, but are limited to their poor initial coulombic efficiency (ICE) and low practical specific capacity due to the large amount of defects. These defects with oxygen containing groups cause irreversible sites for Na+ ions. Highly graphited carbon decreases defects, while potentially blocking diffusion paths of Na+ ions. Therefore, molecular‐level control of graphitization of hard carbon with open accessible channels for Na+ ions is key to achieve high‐performance hard carbon. Moreover, it is challenging to design a conventional method to obtain HCs with both high ICE and capacity. Herein, a universal strategy is developed as manganese ions‐assisted catalytic carbonization to precisely tune graphitization degree, eliminate defects, and maintain effective Na+ ions paths. The as‐prepared hard carbon has a high ICE of 92.05% and excellent cycling performance. Simultaneously, a sodium storage mechanism of “adsorption‐intercalation‐pore filling‐sodium cluster formation” is proposed, and a clear description given of the boundaries of the pore structure and the specific dynamic process of pore filling.

Binder as a bridge in the electrode can bring various components together thus guaranteeing the integrity of electrode and electronic contact during battery cycling. In this review, we summarize the...

Intercalation‐based anode materials can be considered as the most promising anode candidates for large‐scale sodium‐ion batteries (SIBs), owing to their long‐term cycling stability and environmental friendliness, as well as their natural abundance. Nevertheless, their low energy density, low initial coulombic efficiency, and poor cycling lifespan, as well as sluggish sodium diffusion dynamics are still the main issues for the application of intercalation‐based anode materials in SIBs in terms of meeting the benchmark requirements for commercialization. Over the past few years, tremendous efforts have been devoted to improving the performance of SIBs. In this Review, recent progress in the development of intercalation‐based anode materials, including TiO2, Li4Ti5O12, Na2Ti3O7, and NaTi2(PO4)3, is summarized in terms of their sodium storage performance, critical issues, sodiation/desodiation behavior, and effective strategies to enhance their electrochemical performance. Additionally, challenges and perspectives are provided to further understand these intercalation‐based anode materials.

The safety of energy storage equipment has always been as tumbling blockt ot he development of battery,a nd sodium ion battery is no exception. However,a sa nu ltimate solution, the use of non-flammable electrolyte is susceptible to the side effects,a nd its poor compatibility with electrode, causing failure of batteries.H ere,w er eport an on-flammable electrolyte design to achieve high-performance sodium ion battery,which resolves the dilemma via regulating the solvation structure of electrolyte by hydrogen bonds and optimizing the electrode-electrolyte interphase.T he reported non-flammable electrolyte allows stable charge-discharge cycling of both sodium vanadium phosphate@hardc arbon and Prussian blue@hardc arbon full pouchc ell for more than 120 cycles with acapacity retention of > 85 %and high cycling Coulombic efficiency (99.7 %).

Prussian blue analogues (PBAs) have attracted extensive attention as cathode materials in sodium‐ion batteries (SIBs) due to their low cost, high theoretical capacity, and facile synthesis process. However, it is of great challenge to control the crystal vacancies and interstitial water formed during the aqueous co‐precipitation method, which are also the key factors in determining the electrochemical performance. Herein, an antioxidant and chelating agent co‐assisted non‐aqueous ball‐milling method to generate highly‐crystallized Na2‐xFe[Fe(CN)6]y with hollow structure is proposed by suppressing the speed and space of crystal growth. The as‐prepared Na2‐xFe[Fe(CN)6]y hollow nanospheres show low vacancies and interstitial water content, leading to a high sodium content. As a result, the Na‐rich Na1.51Fe[Fe(CN)6]0.87·1.83H2O hollow nanospheres exhibit a high initial Coulombic efficiency, excellent cycling stability, and rate performance via a highly reversible two‐phase transition reaction confirmed by in situ X‐ray diffraction. It delivers a specific capacity of 124.2 mAh g−1 at 17 mA g−1, presenting ultra‐high rate capability (84.1 mAh g−1 at 3400 mA g−1) and cycling stability (65.3% capacity retention after 1000 cycles at 170 mA g−1). Furthermore, the as‐reported non‐aqueous ball‐milling method could be regarded as a promising method for the scalable production of PBAs as cathode materials for high‐performance SIBs.

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