Bilayer Halide Electrolytes for All-Inorganic Solid-State Lithium-Metal Batteries with Excellent Interfacial Compatibility

Inorganic solid-state electrolytes (ISSEs) have been extensively researched as the critical component in all-solid-state lithium-metal batteries (ASSLMBs). Many ISSEs exhibit high ionic conductivities up to 10^-3 S cm^-1. However, most of them suffer from poor interfacial compatibility with electrodes, especially lithium-metal anodes, limiting their application in high-performance ASSLMBs. To achieve good interfacial compatibility with a high-voltage cathode and a lithium-metal anode simultaneously, we propose Li₃InCl₆/Li₂OHCl bilayer halide ISSEs with complementary advantages. In addition to the improved interfacial compatibility, the Li₃InCl₆/Li₂OHCl bilayer halide ISSEs exhibit good thermal stability up to 160 °C. The Li-symmetric cells with sandwich electrolytes Li₂OHCl/Li₃InCl₆/Li₂OHCl exhibit long cycling life of over 300 h and a high critical current density of over 0.6 mA cm^-2 at 80 °C. Moreover, the all-inorganic solid-state lithium-metal batteries (AISSLMBs) LiFePO₄-Li₃InCl₆/Li₃InCl₆/Li₂OHCl/Li fabricated by a facile cold-press method exhibit good rate performance and long-term cycling stability that stably cycle for about 3000 h at 80 °C. This work presents a facile and cost-effective method to construct bilayer halide ISSEs, enabling the development of high-performance AISSLMBs with good interfacial compatibility and thermal stability.