Stable cycling of all-solid-state lithium battery with surface amorphized Li1.5Al0.5Ge1.5(PO4)3 electrolyte and lithium anode

The severe instability with lithium (Li) anode of NASICON-structure Li1.5Al0.5Ge1.5(PO4)3 (LAGP) solid-state electrolyte (SSE) greatly hinders its practical applications in the all-solid-state lithium batteries (ASSLBs) with high energy density and safety. In order to alleviate this issue, here we employed an artificial protective layer of LAGP glass on the surface of ceramic LAGP sheet to construct a surface amorphized electrolyte via a spin-coating co-sintering method. AC impedance test and galvanostatic charge-discharge cycling of Li/electrolytes/Li symmetrical cell suggest that enabled by this glass layer, the surface amorphized LAGP can exhibit better compatibility with Li anode. In addition, with a poly(ethylene oxide) polymer electrolyte in the cathode side, at 0.1 C under 60 °C, the LiFePO4/Li ASSLB using surface amorphized LAGP can keep stable for 120 cycles with a retention of 93.6%, which is more than 13 times of the cell using ceramic LAGP (6.9%). The formation mechanisms of unstable interphases in LAGP/Li interface were briefly summarized, and probable reasons behind the good compatibility between and LAGP glass and Li were discussed.