High Performance and Biodegradable Skeleton Material Based on Soy Protein Isolate for Gel Polymer Electrolyte

A kind of biodegradable and well-sourced soy protein isolate (SPI)/poly(vinyl alcohol) (PVA) composite nanofiber membranes was fabricated via electrospinning and used as skeleton material in gel polymer electrolyte (GPE) of lithium-ion batteries. This study revealed that the proper material proportion, low crystallinity, sufficient porosity and good affinity between nanofiber and the electrode/electrolyte resulted in high saturated electrolyte uptake and conservation rate of the nanofiber membranes. The GPEs based on the SPI/PVA composite nanofiber membranes presented remarkable electrochemical performance, including high ionic conductivity, excellent compatibility with lithium electrode and good electrochemical stability. An ionic conductivity of 3.8 X 10(-3) S cm(-1) and interfacial resistance of 250 Omega. for the GPEs can be obtained when the weight ratio of SPI to RUA in the spinning solution was 3:1, which was more superior to the existing biobased GPEs. In addition, the Li/GPE/LiCoO2 cells with GPEs based on the SPI/PVA (3:1) composite nanofiber membranes displayed the excellent initial discharge capacity and cycle performance. Therefore, the environmental and economical SPI/PVA composite nanofiber membranes with the optimized material proportion can be used as a green skeleton material in GPEs for high performance lithium-ion batteries.