2D-lamellar stacked Na3V2(PO4)2F3@RuO2 as a high-voltage, high-rate capability and long-term cycling cathode material for sodium ion batteries†
Abstract
Uniform two-dimensional (2D)-lamellar stacked Na3V2(PO4)2F3@RuO2 has been successfully synthesized for the first time. As a cathode material for sodium ion batteries, it exhibits high-voltage efficiency with an 87.3% reversible capacity over 3.5 V. Furthermore, it shows high-rate capability with 115.8 mA h g−1 at 20C, and a long-term cyclability with the reversible capacity maintained at 89.5 mA h g−1 even after 1000 cycles. The electrochemical impedance spectroscopy result indicates that the charge transfer resistance decreases and the sodium-ion diffusion coefficient dramatically increases for Na3V2(PO4)2F3@RuO2 compared to Na3V2(PO4)2F3. In addition, we have investigated the effect of HNO3 concentration on the structure and electrochemical performance of Na3V2(PO4)2F3. It is expected that this approach paves the way for designing cathode materials with outstanding performance.