N/S dual-doped KB-decorated Na3V2(PO4)2F3 as high-performance cathode for advanced sodium storage properties

Abstract

Na₃V₂(PO₄)₂F₃ (NVPF) with sodium superionic conductor NASICON) structure’s quick diffusion channel, high energy density, and high operating voltage make it among the most promising cathode materials for batteries that use sodium ions. But its inadequate inherent electronic conductivity and structural stability hinder its excellent electrochemical performance. In this investigation, N and S co-doped Ketjen Black (NSKB) decorated NVPF cathode material (NVPF@NSKB) was effectively produced using a straightforward sol–gel technique. When NSKB is added, NVPF takes on a loose, porous shape. Improving the conductivity of the material, significantly increasing the contact area between the electrode and the electrolyte, helps the material to perform better electrochemical performance. Compared with the original NVPF@C, NVPF@NSKB shows better charging performance, reaching a capacity of 115.4 mAh g⁻¹ at 0.5 C and 103.3 mAh g⁻¹ at 25 C. The battery also demonstrates excellent cycling stability. After 500 cycles at 30 C, the battery’s capacity remained at 80.7 mAh g⁻¹ with minimal capacity loss. This study demonstrates that N and S co-doped KB is an effective strategy to enhance the performance of sodium-ion battery cathode materials, Na₃V₂(PO₄)₂F₃.