Porous poly(vinylidene fluoride) supported three-dimensional poly(ethylene glycol) thin solid polymer electrolyte for flexible high temperature all-solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) are promising candidates for the next-generation all-solid-state batteries due to their good flexibility as well as safety. However, the low ionic conductivity, uncontrolled lithium dendrite growth, poor cyclic performance and high temperature intolerance are still great challenges for their widely applications. In this work, a flexible and dense poly(vinylidene fluoride)/poly(ethylene glycol) (PVDF@PEG) SPE is designed and fabricated via an in-situ thermocuring method, which exhibits a high ionic conductivity of 8.03 × 10 −5 S cm −1 at 30 °C and excellent electrochemical stability window of 5.2 V. More importantly, the Li/PVDF@PEG/Li symmetric cell can be continuously cycled at 0.1 mA cm −2 more than 3200 h without short-circuit at both 60 and 100 °C. Owing to these outstanding merits, the LiFePO 4 /PVDF@PEG/Li pouch cell delivered a high discharge specific capacity of 122.8 mAh g −1 after 1000 cycles at 1C with a capacity retention of 86.36% under 60 °C. Notably, the LiFePO 4 //Li pouch cell also shows excellent cycle stability at 100 °C, exhibiting reversible capacities from 155.5 to 123.1 mAh g −1 under 1C after 1000 cycles.