Enhanced Li+ diffusion by TrFE in PVDF binder for high-performance lithium-sulfur batteries

Abstract

Nowadays, the commercial development of lithium-sulfur (Li–S) batteries is hindered by several critical challenges. In this study, we focus on the role of binders in Li–S batteries, specifically comparing polyvinylidene fluoride (PVDF-TrFE) with commercial polyvinylidene fluoride (PVDF). By copolymerizing vinylidene fluoride (VDF) with trifluoroethylene (TrFE), PVDF-TrFE enhances the toughness of the PVDF, reduces the degree of crystallization, enhances adhesion, and reinforces the structural integrity of the cathode. Consequently, replacing the PVDF binder with PVDF-TrFE significantly improves the transport efficiency of lithium ions (Li⁺) in Li–S batteries. Notably, when compared to the PVDF binder, the Li–S batteries with the PVDF-TrFE binder showed superior electrochemical performance. Batteries with the PVDF-TrFE binder achieved a specific capacity of 742.53 mAh/g after 200 cycles at 0.2 C, and it also exhibited exceptional rate performance. At 5 C current, the reversible discharge specific capacity of the battery reached 462.54 mAh/g. Overall, this study suggests valuable insights into the molecular chain regulation of commercial PVDF binder, paving the way for future research in binders.