An Advanced Gel Polymer Electrolyte for Solid-State Lithium Metal Batteries.

Abstract

All-solid-state lithium metal batteries (LMBs) are regarded as one of the most viable energy storage devices and their comprehensive properties are mainly controlled by solid electrolytes and interface compatibility. This work proposes an advanced poly(vinylidene fluoride-hexafluoropropylene) based gel polymer electrolyte (AP-GPEs) via functional superposition strategy, which involves incorporating butyl acrylate and polyethylene glycol diacrylate as elastic optimization framework, triethyl phosphate and fluoroethylene carbonate as flameproof liquid plasticizers, and Li7La3Zr2O12 nanowires (LLZO-w) as ion-conductive fillers, endowing the designed AP-GPEs/LLZO-w membrane with high mechanical strength, excellent flexibility, low flammability, low activation energy (0.137eV), and improved ionic conductivity (0.42 × 10-3 S cm-1 at 20 °C) due to continuous ionic transport pathways. Additionally, the AP-GPEs/LLZO-w membrane shows good safety and chemical/electrochemical compatibility with the lithium anode, owing to the synergistic effect of LLZO-w filler, flexible frameworks, and flame retardants. Consequently, the LiFePO4/Li batteries assembled with AP-GPEs/LLZO-w electrolyte exhibit enhanced cycling performance (87.3% capacity retention after 600 cycles at 1 C) and notable high-rate capacity (93.3 mAh g-1 at 5 C). This work proposes a novel functional superposition strategy for the synthesis of high-performance comprehensive GPEs for LMBs.