In-situ constructing slow-release Li-Al-O interface layer for lithium metal batteries to enhance interface stability and suppress lithium dendrite growth

Composite polymer electrolytes (CPEs) have shown extraordinary promise for use in all-solid-state lithium metal batteries (LMBs) because of their tunable merits in ionic conductivity and mechanical flexibility. Their practical application is however hindered by the poor interface stability and the uncontrollable Li dendrite formation. Addressing these two issues, we report an in-situ formed Li-Al-O interface layer between CPEs and Li metal anode by introducing Al2O3 nanoparticles in CPEs. X-ray photoelectron spectroscopy results indicated that the CPE-Al2O3 could slowly release Al atoms which react with Li metal to form the current Li-Al-O interface layer. We highlight that the Li-Al-O interface layer can stabilize lithium deposition/stripping over 1400 h in lithium symmetric batteries, and afford an impressive cycle life of 300 cycles in LiFePO4-Li batteries with almost no capacity loss. The present findings demonstrate that in-situ constructing a slow-release Li-Al-O interface layer is an easy and effective approach to stabilize the solid electrolyte interface and suppress the Li dendrites growth. Furthermore, the obtained batteries show excellent cycling stability, indicating the strategy with in-situ formed CPEs shed light on improving the processability of fabrication of high-performance electrolytes.