An in situ solidifying strategy enabling high-voltage all-solid-state Li-metal batteries operating at room temperature

Abstract

At present most reported all-solid-state Li-metal batteries (ASSLBs) have to operate at elevated temperature due to the huge resistances at solid–solid interfaces. Also, the poor stability of solid-state electrolytes (SSEs) against both Li metal and high-voltage cathodes largely restricts the development of high-voltage ASSLBs featuring high energy density. Herein, a succinonitrile-based solid polymer interlayer (SPI) is in situ introduced at the Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP)–Li and LAGP–cathode interfaces. The SPI perfectly fills all cracks and voids at solid–solid interfaces, and exhibits high ionic conductivity and a wide electrochemical window up to 4.8 V, which not only provides fast interfacial lithium-ion transport, but also significantly improves the interfacial stability of the SSEs against both Li metal and high-voltage layered oxide cathodes. Therefore, the SPI-based symmetric cell shows stable cycling at 0.1 mA cm⁻² for 600 h and a high critical current density of 7 mA cm⁻². The LiNi_0.8Co_0.15Al_0.05O₂–SPI–LAGP–SPI–Li cell shows a high capacity of 200 mA h g⁻¹ at 0.1C and stable cycling after 100 cycles at 0.5C with a capacity retention of 80% at room temperature. This work presents an effective and practical strategy to achieve outstanding performance of room-temperature ASSLBs with high output voltage.