3Li2S-2MoS2 filled composite polymer PVDF-HFP/LiODFB electrolyte with excellent interface performance for lithium metal batteries

Abstract

Solid polymer electrolytes (SPEs) are close to commercialization owing to their high flexibility, low cost, and easy processing. However, the further commercial applications of SPE are hindered by low ionic conductivity and poor mechanical properties. To solve the problems, a porous and intercalated 3Li2S-2MoS2 (LMS) was prepared as an active filler. LMS and lithium oxalyldifluroborate (LiODFB) were embedded with the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in a composite intercalated solid polymer electrolyte (CSE-LMS). The CSE-LMS exhibits excellent properties such as high ionic conductivity (2.51 × 10-4 S·cm−1 at 60 ℃) with a favorable stability electrochemical window of 4.8 V (vs. Li/Li+), superior interface stability with lithium metal and outstanding mechanical strength. The LiCoO2/CSE-LMS/Li cell was assembled to construct a high specific energy device, which delivered excellent C-rate performance and a specific capacity of 145.79 mA·h·g−1 with a capacity retention of > 86.22% after 200 cycles at 0.5C. The LMS reduces polymer crystallinity and stablizes the interface conformation achieved by LMS interacting with PVDF-HFP and LiODFB. The results suggest that CSE-LMS12 doped with 12 wt% LMS is a promising SPE for solid-state batteries.