全固态钠离子电池硫系化合物电解质

全固态钠离子电池具有资源丰富、安全性高等优势,作为未来大规模储能的重要选择而成为近年来先进二次电池前沿研究热点。钠离子硫系化合物电解质室温离子电导率高、弹性模量高、容易冷压成型,能增强电极/电解质界面接触、减小界面阻抗、缓冲电极材料在充放电过程中的应力/应变,是全固态钠离子电池的研究重点。本文对钠离子硫系化合物固态电解质的结构及性质进行了总结,讨论了硫系化合物电解质的本征特性、与电极的界面稳定性,并介绍了硫系化合物全固态钠离子电池的研究现状,最后分析了硫系化合物电解质面临的挑战及今后的发展方向。

Chalcogenide Electrolytes for All-Solid-State Sodium Ion Batteries

All-solid-state sodium ion batteries (ASIBs) are important for future large-scale energy storage applications. ASIBs have come to occupy an important position in research on advanced secondary batteries in recent years owing to their advantages of abundance in resources, low cost, long lifetime, and high safety. As the key to the success of ASIBs, solid-state electrolytes such as polymers, oxide ceramics, and sulfide glass-ceramics have always attracted immense interest. Chalcogenide electrolytes for ASIBs have high room-temperature conductivity, high elastic modulus, and can be easily pressed into a mold at room temperature; hence, they are the research focus in ASIBs. This paper summarized recent studies on the structure and properties of chalcogenide electrolytes for ASIBs. These studies demonstrate the relationship between the phase structure and ionic conductivity of sulfide-based electrolytes and selenide-based electrolytes. Besides, arguments that the sodium vacancy in the crystal structure dominates ionic conduction, and creating a sodium vacancy via cation substitution is the principal strategy to increasing ionic conduction, are discussed. Further, the intrinsic chemical stability and interface stability between the electrode and electrolyte are highlighted. Based on the soft and hard acid and base theory, some studies adopted various anion/cation ion substitution strategies to improve the chemical stability of chalcogenide electrolytes in humid air. Particularly, the inconsistency in the electrochemical stability window of a representative chalcogenide electrode, Na₃PS₄, as measured by a semi-blocking electrode and calculated by first-principles, is compared. Additionally, to develop all-solid-state Na-S and Na-O₂ batteries with high capacity, the nonnegligible interface instability of the sulfide electrode against the sodium metal anode and feasible solutions are summarized. Next, the research progress on ASIBs using chalcogenide electrolytes is reviewed. Chalcogenide electrolytes are restricted by the electrochemical stability window and chemical compatibility with electrode materials; hence, they are expected to only be applicable to ASIBs using sulfur, sulfide, and organic matter as the cathode and Na-Sn alloy as the anode. However, these ASIBs have long cycling life (> 500 cycles), illustrating their potential applications in large-scale energy storage power stations. Finally, we comprehensively evaluate the ionic conductivity, stability against humid air, stability of the interface, electrochemical stability window, and ease of preparation of typical chalcogenide electrolytes, including Na₃PS₄, Na₃PSe₄, Na₃SbS₄, Na₃SbSe₄, Na₁₀SnPS₁₂, and Na₁₁Sn₂PS₁₂. Moreover, we highlight the challenges and propose possible solutions toward the development of chalcogenide electrolytes in future. Advanced technologies in fine synthesis, in situ characterization, and surface/interface modification are essential to overcome existing challenges and promote the development of chalcogenide-electrolyte-based ASIBs.