Improved Na storage performance of Na3V2(PO4)3 cathode material for sodium-ion batteries by K-Cl co-doping

Abstract

Abstract As a promising cathode material for sodium-ion batteries (SIBs), Na3V2(PO4)3 (NVP), the typical NASICON (Na super-ionic conductor)-structure cathode material, has received much attention resulting from its high working potential and excellent structural stability. However, it has always suffered from low electroconductivity, which largely limits its application in SIBs. Herein, to improve the electrochemical performance, we developed potassium and chlorine co-doped Na3V2(PO4)3/carbon particles (NKVPCl/C) using a spray-drying method combined with a calcinating process and adopted them as cathode materials for SIBs. We studied in detail how K+ and Cl− affected the electrochemical performance. The NKVPCl/C-2 particles displayed a highly initial discharge capacity of 109.6 mA h g−1 at 0.2 C, and had a superior cycling stable property (nearly 100% of initial discharge capacity after 500 cycles at 5 C). The excellent electrochemical performance of NKVPCl/C can be attributed to its higher Na+ diffusion and electron conduction, which indicates that the strategy of co-doping K-Cl is an effective tactic for improving the property of NVP in SIBs.