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 Li1.5Al0.5Ge1.5(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 LiNi0.8Co0.15Al0.05O2–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.