Cycling properties of Na3V2(PO4)2F3 as positive material for sodium-ion batteries

The research into sodium-ion battery requires the development ofhigh voltage cathodic materials to compensate for the potential of the negative electrode materials which is usually higher than the lithium counterparts. In this framework, the polyanionic compound Na3V2(PO4)2F3 was prepared by an easy-to-scale-up carbothermal method and characterized to evaluate its electrochemical per- formances in halfcell vs. metallic sodium. The material shows a specific capacity (115 mAh g−1) close to the theoretical limit, good coulombic efficiency (>99%) and an excellent stability over several hundred cycles at high rate. High-loading free-standing electrodes were also tested, which showed interesting performances in terms of areal capacity and cyclability.