Feo_0.7F_1.3/C nanocomposite as a high-capacity cathode material for sodium-ion batteries

Searching high capacity cathode materials is one of the most important fi elds of the research and development of sodium-ion batteries (SIBs). Here, we report a FeO_0.7F_1.3/C nanocomposite synthesized via a solution process as a new cathode material for SIBs. This material exhibits a high initial discharge capacity of 496 mAh g^-1 in a sodium cell at 50 °C. From the 3^rd to 50^th cycle, the capacity fading is only 0.14% per cycle (from 388 mAh g^-1 at 3^rd the cycle to 360 mAh g^-1 at the 50^th cycle), demonstrating superior cyclability. A high energy density of 650 Wh kg^-1 is obtained at the material level. The reaction mechanism studies of FeO_0.7F_1.3/C with sodium show a hybridized mechanism of both intercalation and conversion reaction.