Enhancement of the rate capabilities for all-solid-state batteries through the surface oxidation of sulfide solid electrolytes

摘要

Lithium-ion conducting sulfide solid electrolytes are promising candidates for all-solid-state lithium ion batteries, which are being developed to meet the increasing demand for high-capacity rechargeable batteries. In this study, a new type of solid electrolyte with a core-shell structure consisting of oxidized-shell surrounding sulfide solid electrolyte (O-SSE) was developed. The influence of the surface oxidation of 80Li(2)S center dot 20P(2)S(5) glass-ceramic electrolyte on a battery using 4 V class cathode material was investigated. The results of X-ray photoelectron spectroscopy depth profiling confirmed that > 80% of the surface of the O-SSE was oxidized from P-S bonds to P-O bonds, and the oxygen remained localized at the surface. The interfacial resistance between the sulfide solid electrolyte and LiNi0.8CO0.15Al0.05O2 (NCA) was significantly decreased by this surface oxidation. The ASSB cell using O-SSE as a cathode solid electrolyte exhibited better discharge performance than 80Li(2)S center dot 20P(2)S(5) glass-ceramic electrolyte and could discharge at a high current density of 2.0 mA.cm(-2). These results demonstrate that surface oxidation of a sulfide solid electrolyte is a new and effective method for reducing the interfacial resistance between the cathode material and solid electrolyte and improving the charge-discharge performance.