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@PCNIF 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@PCNIF 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 current density. The ex-situ atomic force microscope (AFM) images reveal the process of gradually forming SEI on the surface of C@MoS2@PCNIF during the first cycle. Moreover, the C@MoS2@PCNIF is assembled for potassium ion capacitor (PIC) with activated carbon (AC) to evaluate the potential application, which presents an excellent cycle stability.