Trumpet-Like ZnS@C Composite for High-Performance Potassium Ion Battery Anode.

ZnS has acquired increasing attention for high-performance PIBs anode because of its remarkable theoretical capacity, and redox reversibility for conversion reaction. However, the larger volume variation and delayed reaction kinetics for the ZnS in the discharge/charge processes lead to pulverization and severe capacity degradation. Herein, the trumpet-like ZnS@C composite was synthesized by template method by using sodium citrate as carbon source followed by vulcanization process. As potassium ion batteries (PIB) anode, ZnS@C composite exhibits good rate performance and long life (stable reversible capacity of 107.8 mAh/g over 2000 charge-discharge cycles at 5 A/g and high reversible capacity of 310 mAh/g at 0.1 A/g). The outstanding electrochemical performance of the ZnS@C composite is ascribed to its unique structure, which can mitigate the volume expansion of ZnS in the charge discharge process, expand the contact area between the electrode and electrolyte, and improve the conductivity of electrode materials by the introduction of carbon layer. This method of synthesizing trumpet-like ZnS@C composite provides an important strategy for obtaining potassium ion batteries anode with long cycle.