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We demonstrate an economical polytetrafluoroethylene-assisted fluorination method to synthesize three binary sodium-rich fluorides Na2MVF7 (M = Mn, Fe, and Co). The optimal Na2FeVF7 cathode delivers a high reversible capacity of...

With high theoretical capacity and operating voltage, KVPO 4 F is a potential high energy density cathode material for potassium-ion batteries. However, its performance is usually limited by F loss, poor electronic conductivity, and unsteady electrode/electrolyte interface. Herein, a simple one-step sintering process is developed, where vanadium−oxalate−phosphite/phosphate frameworks and fluorinated polymer are used to synthesize carbon-coated KVPO 4 F nanoplates. It is found that the V−F−C bond generated by fluorinated-polymer-derived carbon at the interface of KVPO 4 F/C nanoplates diminishes the F loss, as well as enhances K-ions migration ability and the electronic conductivity of KVPO 4 F. The as-synthesized KVPO 4 F/C cathode delivers a reversible capacity of 106.5 mAh g −1 at 0.2 C, a high working voltage of 4.28 V, and a rate capability with capacity of 73.8 mAh g −1 at the ultrahigh current density of 100 C. In addition, a KVPO 4 F/C//soft carbon full cell exhibits a high energy density of 235.5 Wh kg −1 .

Layered transition-metal oxides have engendered intensive attention as advanced cathode materials of potassium-ion batteries (PIBs). Nevertheless, their practical application to PIBs is hindered by the unsatisfactory cycling stability and rate...

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