Interface engineering of Li1.5Al0.5Ge1.5(PO4)3 electrolytes via in-situ polymer–cerium hybrid interlayers for high-performance all-solid-state lithium metal batteries

NASICON-type solid electrolytes exhibit substantial potential for application in all-solid-state lithium metal batteries (ASSLMBs) with a high energy density, attributed to their broad electrochemical window, high ionic conductivity, and excellent air stability. Nevertheless, the practical application is severely limited by inadequate chemical stability upon interaction with lithium metal. To address this challenge, a multifunctional interlayer was developed to suppress the detrimental reaction between Li metal and Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP). The interlayer exhibits outstanding interfacial compatibility and minimized interfacial This interlayer was fabricated through the in-situ solidification of poly(ethylene glycol) methyl ether acrylate with cerium trifluoride, combined with ionic liquid (named as PCEIL). The interlayer exhibits outstanding interfacial compatibility and minimized interfacial resistance, which enables the Li|PCEIL-LAGP-PCEIL|Li symmetric battery to achieve stable cycling over 1000 h at 0.1 mA cm −2 without short-circuiting. Additionally, this interlayer enables superior performance in Li|PCEIL-LAGP-PCEIL|LiFePO 4 cells, with a remarkable capacity retention of 96.5 % after 250 cycles at 0.2C, and an impressive average Coulombic efficiency of 99.8 %. Therefore, this work provides effective strategies to stabilize NASICON-type solid electrolytes and lithium metal, promoting the development of high-performance ASSLMBs.