PEO/PVDF–HFP/LLZTO Composite Solid Polymer Electrolyte for High-Performance All-Solid-State Lithium Metal Batteries

A composite solid polymer electrolyte (CSPE) is the best candidate in all-solid-state lithium metal batteries because of its flexibility, high safety, wide electrochemical stability, relatively high ionic conductivity, and excellent compatibility with the lithium metal. In this work, the garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) is introduced into a poly(ethylene oxide) (PEO)/poly(vinylidene fluoride–hexafluoropropylene) (PVDF–HFP)-based CSPE (PEO/PVDF–HFP/LLZTO CSPE). The PEO/PVDF–HFP/LLZTO CSPE possesses a high lithium-ion transference number of 0.47, a high ionic conductivity of 2.65 × 10–4 S cm–1, a wide electrochemical window of 5.55 V vs Li+/Li, and effective inhibition of lithium dendrite growth for 1000 h with a current density of 0.10 mA cm–2. Furthermore, the Li//LiFePO4 cell assembled with the PEO/PVDF–HFP/LLZTO CSPE delivers superior rate capability and good cycling stability. Therefore, the PEO/PVDF–HFP/LLZTO CSPE is a very promising candidate for high-performance all-solid-state lithium metal batteries.