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

Abstract

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. The 3D nanofiber membrane (PAL-3-C12) prepared with an adjusted weight ratio of polyacrylonitrile (PAN)/poly-L-lactic acid (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 LiFePO4 full cell retains capacity retention of 97.63% after 140 cycles at 1C.

Keywords

• 3D nanofiber membrane
• Polymer membrane skeleton
• Gel polymer electrolyte
• Electrospinning method
• Lithium metal battery