Thermal stability of PVDF-HFP based gel electrolyte for high performance and safe lithium metal batteries

Gel polymer electrolytes (GPEs) have garnered significant attention due to their efficacy in addressing safety concerns associated with liquid electrolyte leakage. However, the frail mechanical properties and low thermal stability of GPEs have constituted significant obstacles to their commercialization. In this paper, safe GPEs with excellent mechanical properties and high thermal stability were prepared by introducing high-strength and lithophilic cellulose acetate (CA) into PVDF-HFP gel electrolytes. The incorporation of CA facilitates the dissociation and transport of Li salts, and the formation of a hydrogen bonding network between the -OH of CA and the -F of the PVDF-HFP substrate was identified through FTIR testing. The thermal stability was elucidated through pyrolysis kinetics, and the activation energy was calculated. The pyrolysis products were compared through a TG-FTIR-MS test to demonstrate the high-temperature resistance of the FPF-CA membrane. The prepared GPEs exhibited high ionic conductivity (1.087 x 10-3 S/cm) and some self-extinguishing properties at room temperature, with a higher electrochemical window of 4.81 V and a high Li+ mobility number of 0.56. The capacity retention was 93% after 600 cycles at 1C.