Deciphering Interfacial Stability of Sulfide and Halide-Based Electrolytes via Operando X-ray Photoelectron Spectroscopy
Zhicong Liu, Jianming Tao, Han Jiang, Yubing Wu, Lin Liang, Yanmin Yang, Yue Chen, Zhigao Huang, Yingbin Lin
Abstract
Combined solid electrolytes address cathode-anode compatibility in all-solid-state Li-ion batteries (ASSLBs), yet interface stability and ion transport mechanisms between different electrolytes remain unclear. Herein, we investigate Li 6 PS 5 Cl (LPSC), Li 3 InCl 6 (LIC), and Li 1.75 ZrO 0.5 Cl 4.75 (LZOC) composite electrolytes through electrochemical analysis and operando X-ray photoelectron spectroscopy. Our results reveal that the electrostatic potential difference between LPSC and LIC inhibits Li + migration, leading to the decomposition of LIC into InCl 3 and LiCl, causing battery failure. In contrast, LZOC forms an oxygen-rich interphase with LiCoO 2 (LCO), showing better interfacial stability. The electrostatic potential difference between LZOC and LPSC promotes Li + diffusion, maintaining interface stability even as LPSC decomposes, thereby preventing severe degradation of LZOC. Therefore, the LCO-LZOC composite cathode exhibits better electrochemical performance than LCO-LIC. This study elucidates the basic mechanism of interfacial reaction and ion diffusion in sulfide–halide electrolytes and emphasizes the key role of electrolyte compatibility in ASSLBs failure pathways.