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 Fe7S8/C hybrid nanocages reinforced by defect-rich MoS2 nanosheets (Fe7S8/C@d-MoS2) 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 MoS2 nanosheets dramatically promotes the potassium-ion diffusion coefficient. The ex-situ measurements revealed the potassium-ion storage mechanism in the Fe7S8/C@d-MoS2 composite. Benefitting from the tailored structural design, the Fe7S8/C@d-MoS2 hybrid nanocages show high reversible capacity, exceptional rate property, and superior cyclability.