Chelating-Type Binders toward Stable Cycling and High-Safety Transition-Metal Sulfide-Based Lithium Batteries

Abstract

Conversion-type transition-metal sulfides (MS_x) are considered promising cathodes due to their low cost, easy availability, and high energy density. However, MS_x cathodes experience severe capacity decay when cycling in conventional carbonate-based electrolytes because of irreversible nucleophilic reactions between carbonate solvents and polysulfide intermediates. To address this issue, a series of chelating-type binders has been designed for enabling MS_x to function effectively. As a result, a typical transition-metal sulfide FeS₂ cathode can work reversibly with a high capacity of 527.3 mAh g^–1 over 300 cycles, retaining 76.9% capacity under an ultrahigh loading of 5.6 mAh cm^–2. Additionally, a new type of battery featuring FeS₂ cathodes coupled with LiC₆ anodes in carbonate electrolyte has been developed for high stability (72.0% retention after 300 cycles) and safety. This work demonstrates the potential of conversion-type lithium batteries for achieving long cycle life and high safety.