Poly (vinyl ethylene carbonate)-based dual-salt gel polymer electrolyte enabling high voltage lithium metal batteries

Abstract

Rechargeable lithium metal batteries (LMBs) have been regarded as one of the most promising next-generation energy-storage systems due to their high theoretical energy density. However, the practical application of LMBs is greatly impeded by poor high-voltage tolerance and safety concerns originated from flammable organic carbonate-based liquid electrolytes. Herein, a novel dual-salt gel polymer electrolyte (DS-GPE) is prepared via in situ polymerization of vinyl ethylene carbonate (VEC) and pentaerythritol tetra acrylate (PETEA) monomers in a poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) porous structure. The newly developed DS-GPE shows high ionic conductivity (6.9 mS cm−1) at room temperature, adequate Li+ transference number (tLi+= 0.512), outstanding oxidative resistance (5.3 V vs. Li/Li+) and favorable interfacial compatibility. Stable interfacial layers are rich in B-, F-, components on both the Li metal anode and high-voltage LiCoO2 cathode, realizing excellent cycling stability in Li||Li symmetrical cells, and a capacity retention of 83.42% over 100 cycles with average Coulombic efficiency of 99.86% in Li||LiCoO2 cell.