Biodegradable composite polymer as advanced gel electrolyte for quasi-solid-state lithium-metal battery

The development of low-cost and eco-friendly gel polymer electrolytes (GPEs) with a wide window, ideal compatibility, and structural stability is an effective measure to achieve safe high-energy-density lithium-metal batteries. Herein, a biodegradable composite polyacrylonitrile/poly- l -lactic acid nanofiber membrane (PAL) is synthesized and used as a robust skeleton for GPEs. A 3D nanofiber membrane (PAL-3-C12) prepared with an adjusted weight ratio of PAN/PLLA and spinning solution concentration delivers decent thermal stability, biodegradability, and liquid electrolyte absorbability. The “passivation effect” of PAN upon lithium metal is effectively alleviated by hydrogen bonds formed in the PAL chains. These advantages enable PAL GPEs to work stably to 5.17 V while maintaining high ionic conductivity as well as excellent corrosion resistance and dielectric properties. The interfacial compatibility of optimized GPEs promotes the stable operation of a Li||PAL-3-C12 GPEs||Li symmetric battery for 1000 h at 0.15 mA cm −2 /0.15 mA h cm −2 , and the LiFePO 4 full cell retains capacity retention of 97.63% after 140 cycles at 1C. • A biodegradable PAL composite nanofiber membrane constructed by interlaced nanofibers as a robust host for GPEs has been synthesized via electrospinning. • The optimized PAL fiber networks exhibit good thermal stability, biodegradability, and liquid electrolyte absorbability. • The “passivation effect” of PAN upon Li metal is effectively alleviated by hydrogen bonds formed between PAN and PLLA chains. • PAL-3-C12 GPEs exhibit superior interfacial compatibility with electrodes.