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

Conversion-type transition-metal sulfides (MSx) are considered promising cathodes due to their low cost, easy availability, and high energy density. However, MSx 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 MSx 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.