Construction of high conductivity carbon-coated MoS₂ on porous carbon nanofibers for synergistic potassium storage

The anode materials with high capacity, excellent reversibility and good cycling stability are important for potassium-ion batteries (PIBs) application. Herein, we construct a freestanding anode structure by bounding the carbon-coated MoS₂ on porous carbon nanofibers (C@MoS₂@PCNF) for PIBs. Benefiting from the frame supporting of carbon nanofiber and carbon coating, the C@MoS₂@PCNF materials have high conductivity and firm electrode structure. The porous structure of the carbon nanofibers alleviate the volume expansion of the MoS₂ nanosheets during the reaction process effectively. Meanwhile, the MoS₂ nanosheets have abundant dislocation defects and larger interlayer spacing. The C@MoS₂@PCNF materials present excellent potassium storage performance used as PIBs anode. It delivers a high reversible capacity and a superior rate capacity, corresponding value are 323 mA h g⁻¹ after 100 cycles at 100 mA h g⁻¹ current density and 198 mA h g⁻¹ at 1000 mA g⁻¹ current density. The ex-situ atomic force microscope (AFM) images reveal the process of gradually forming SEI on the surface of C@MoS₂@PCNF during the first cycle. Moreover, the C@MoS₂@PCNF is assembled for potassium ion capacitor (PIC) with activated carbon (AC) to evaluate the potential application, which presents an excellent cycle stability.