High-Performance PVDF-HFP-PVAc-LLZTO Composite Solid-State Electrolyte for Lithium Metal Battery

Abstract

Composite solid-state electrolytes are highly promising contenders for next-generation lithium-metal batteries due to their high safety, good flexibility, and compatibility with lithium metal. In this work, Poly(vinyl acetate) (PVAc) was incorporated into PVDF-HFP in order to reduce the crystallinity of the PVDF-HFP matrix, improve the ionic conductivity of the electrolyte, and greatly reduce the interfacial impedance of the electrolyte by utilizing the low-temperature flexibility, excellent amorphous nature, and strong bonding properties of PVAc. On this basis, the active filler LLZTO was introduced to further reduce the crystallinity of the PVDF-HFP matrix and provide more Li+ transport channels. The PP60-10LLZTO composite solid electrolyte has exceptional mechanical and electrochemical characteristics with a high ionic conductivity of 7.2*10−4 S cm−1 and the Li+ transference number of 0.57 at 30 °C. The assembled LFP/Li battery can be stably cycled for 450 cycles at 30 °C and 0.5C, and its capacity retention rate is as high as 89%. The strategy of constructing composite solid-state electrolytes in this paper presents new insights for designing and developing high-performance solid-state lithium metal batteries.