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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 .
Ge et al. (Fri,) studied this question.