MoSe 2 /N‐Doped Carbon as Anodes for Potassium‐Ion Batteries

Abstract Potassium‐ion batteries (PIBs) have attracted considerable attention due to the low redox potential, low price, and abundance, in comparison to lithium and sodium. Herein, a novel potassium MoSe 2 /N‐C battery with a new electrolyte, 1 m potassium bis(fluoro‐slufonyl)imide in ethyl methyl carbonate, is reported. The MoSe 2 /N‐C composite, which consists of carbon‐coated MoSe 2 nanosheets, is synthesized through solvothermal and annealing method. As an anode material for PIBs, it exhibits an outstanding rate performance and long cycling stability. Meanwhile, a reversible capacity of 258.02 mA h g −1 is achieved after 300 cycles at 100 mA g −1 , obtaining a Coulombic efficiency close to 100%. Even at a high current density, it can maintain 218 and 197 mA h g −1 at 500 and 1000 mA g −1 , respectively. The charge/discharge mechanism of MoSe 2 /N‐C as the anode material for PIBs is investigated. These results reveal that the insertion and the extraction of K + will lead to a phase transition of MoSe 2 . During the charge process, a part of the MoSe 2 will transform to Mo 15 Se 19 and the major final discharge product is K 5 Se 3 .