Carbon‐Coated NaVPO4F as a High‐Capacity Cathode for Aqueous Sodium‐Ion Battery

Abstract NaVPO4F has garnered significant attention as a promising cathode material for non‐aqueous sodium‐ion batteries due to its high theoretical specific capacity and appropriate potential. However, the dissolution of vanadium component of NaVPO4F in aqueous electrolytes has restricted its application in aqueous sodium‐ion batteries (ASIBs). Herein, we report the use of carbon‐coated NaVPO4F as a cathode material in ASIBs. This cathode material exhibited a discharge capacity of 111 mAh g−1 at 0.5 A g−1 in a concentrated 17 m NaClO4 aqueous solution and demonstrated capacity retention of 74.4 % over 100 cycles. The experimental results confirmed that the carbon coating on NaVPO4F and high‐concentration NaClO4 aqueous electrolyte exhibited positive effects in restraining vanadium dissolution. Additionally, when configuration with NaTi2(PO4)3@C as anode, the full cell exhibited a capacity of 43.9 mAh g−1 with an average operating voltage of 1.2 V at a current density of 0.5 A g−1 in a concentrated 17 m NaClO4 aqueous electrolyte. These outcomes underscore the potential of NaVPO4F@C as a promising cathode material for ASIBs.