硫化物固态电解质因离子电导率高、机械延展性好、界面接触性优异等优点，成为全固态电池领域的研究热点和前沿。但其较差的电化学稳定性严重限制了其应用。目前学术界仅限于意识到这一问题，对其电化学稳定性差的机理研究还不够深入，且主流观点中用“表面钝化层”理论解释电化学稳定性的提升并不准确。基于此研究现状，本项目重点研究硫化物固态电解质在不同化学势下的分解反应过程，并分析多种因素对该分解反应的影响，深入理解其反应机理。然后结合申请人已有研究成果，从体相和表面相组成结构的角度，总结并衍生出新的提高电化学稳定性的有效方法。进而剖析该过程中电化学稳定性提升的机理，对现有理论提出修正和完善意见，并设计实验进行验证，加深理解并不断优化，开发出真正高压稳定的硫化物固态电解质。最后，通过匹配优化电极材料、改善界面并开发新型硫化物全固态电池模具，实现高能量密度、高功率密度、长寿命、易产业化的硫化物全固态电池。

Sulfide solid-state electrolyte has become the research frontier in the field of all solid-state batteries due to its advantages of high ionic conductivity, good mechanical properties and excellent interfacial contact with electrodes. However, the poor electrochemical stability severely limits its application. The research community has realized this problem, but not been able to reveal its in-depth decomposition mechanism. Moreover, the mainstream view of "surface passivation layer" theory is not exactly accurate for explaining the improvement mechanism of electrochemical stability. Based on this situation, this project aims to first perform a complete and in-depth analysis on the decomposition process of sulfide solid-state electrolyte under different chemical potentials. Then the influence of various factors on decomposition reaction is taken into consideration to establish a multi-dimensional database. New effective methods for improving the electrochemical stability are summarized and derived from previous studies of the applicant, in terms of bulk and surface modification. Furthermore, new creative mechanism is proposed to replace the existing theory for better understanding in improving electrochemical stability, verified by specially-designed experiment. Based on the above research, sulfide solid-state electrolytes with wide voltage window are expected to be optimized. Sulfide all-solid-state battery with high energy density, high power density, long cycling stability is to be realized by matching electrode materials, improving the interface and developing new devices.