CuP_(2) as high-capacity and long-cycle-life anode for potassium-ion batteries

Metal phosphides have shown great potential for potassium-ion batteries because of their high theoretical specific capacity.Nevertheless,most of the metal phosphide anodes are plagued by rapid capacity decay(caused by the large volume changes during the discharge/charge process),which would restrict their further practical application.Herein,a chemically bonded CuP_(2)/C composite was prepared by a facile high-energy ball milling method.A potassium bis(trifluoromethanesulfonyl)imide(KFSI)-based electrolyte was adopted instead of a conventional KPF6-based electrolyte for the CuP_(2)/C composite anode.Benefiting from the synergistic effects of the formation of strong P-O-C chemical bonds and the KFSIbased electrolyte,the CuP_(2)/C composite anode exhibited high reversible capacity(451.4 mAh g^(-1) at50 mA g^(-1)),excellent rate performance(123.5 mAh g^(-1) at 1000 mA g^(-1)),and superior cycling stability(300 mAh g^(-1) after 100 cycles).This work paves the way for the development of high-performance CuP_(2) anode for potassium-ion batteries.