A Robust Strategy for Engineering Fe₇S₈/C Hybrid Nanocages Reinforced by Defect-Rich MoS₂ Nanosheets for Superior Potassium-Ion Storage

Metal sulfides have attracted tremendous research interest for developing high-performance electrodes for potassium-ion batteries (PIBs) for their high theoretical capacities. Nevertheless, the practical application of metal sulfides in PIBs is still unaddressed due to their intrinsic shortcomings of low conductivity and severe volume changes during the potassiation/depotassiation process. Herein, robust Fe 7 S 8 /C hybrid nanocages reinforced by defect-rich MoS 2 nanosheets (Fe 7 S 8 /C@d-MoS 2 ) were designed, which possess abundant multichannel and active sites for potassium-ion transportation and storage. Kinetic analysis and theoretical calculation verify that the introduction of defect-rich MoS 2 nanosheets dramatically promotes the potassium-ion diffusion coefficient. The ex-situ measurements revealed the potassium-ion storage mechanism in the Fe 7 S 8 /C@d-MoS 2 composite. Benefitting from the tailored structural design, the Fe 7 S 8 /C@d-MoS 2 hybrid nanocages show high reversible capacity, exceptional rate property, and superior cyclability.