Zinc complex-based multifunctional binders for lithium sulfide-based lithium–sulfur batteries

Abstract

Lithium sulfide (Li₂S) is a promising cathode material for lithium–sulfur batteries (LSBs) due to its compatibility with lithium-free anodes and commercial electrode processing. However, its high moisture sensitivity and processing difficulties pose challenges, particularly in identifying suitable binders. Here, we report a fluorine-free binder based on a zinc acetate triethanolamine (Zn(OAc)₂·TEA) complex, which exhibits enhanced specific capacity, rate capability, and cycling stability compared to the commonly used PVDF binder. These improvements are attributed to the strong lithium polysulfide (LPS) trapping ability and redox catalytic activity of the Zn(OAc)₂·TEA complex. To improve mechanical robustness and solution stability, polyethylenimine (PEI) was incorporated to form a Zn(OAc)₂·TEA/PEI hybrid binder. Electrochemical testing revealed that Li₂S cathodes employing Zn(OAc)₂·TEA/PEI with 10 wt% PEI delivered superior rate performance, high discharge capacity, and excellent long-term cycling stability. This work presents a promising fluorine-free binder strategy that integrates LPS trapping and redox catalysis, advancing the practical development of high-performance Li₂S-based LSBs.