Hybridizing poly(vinylidene fluoride-co-hexafluoropropylene) with Li6.5La3Zr1.5Ta0.5O12 as a lithium-ion electrolyte for solid state lithium metal batteries

Polymer/ceramic composite solid electrolyte is an appealing solution for the exploitation of flexible solid-state lithium-metal batteries. Here we report a solid-state Li-ion electrolyte composing of poly(vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) polymer, ceramic powder Li6.5La3Zr1.5Ta0.5O12 (LLZTO) and lithium salt LiTFSI. The composite electrolyte exhibits a high ionic conductivity of 8.80 × 10−5 S·cm−1 at room temperature. A coin battery with LiFePO4 cathode is cycled under 0.5 C at room temperature for long cycles, achieving a Coulombic efficiency of 99.6% without virtually capacity loss (1st: 101.4 mAh·g−1 and 500th: 110.9 mAh·g−1). Such excellent performance can be ascribed to the formation of high ionic conductivity by LLZTO active garnet reducing polymer crystallinity. These results show that the developed polymer/ceramic composite has potential to be a high-performance electrolyte for solid-state lithium-metal batteries.