Achieving long-term cycling stability in Na3V2(PO4)3 cathode material through polymorphic carbon network coating

Abstract

Na₃V₂(PO₄)₃ (NVP) material has evolved as a significant candidate for electrode materials in the development of sodium-ion batteries. However, the low conductivity of NVP material leads to low cycling performance, limiting their application in high-efficiency battery materials. To address this issue, this work proposes a novel strategy for materials design through constructing 3D network carbon-coatings on the surface of NVP materials. The carbon-coatings are achieved via a combination of sol-gel technique and heat treatment using pyrolytic carbon (C), carbon nanotubes (CNTs) and graphene (GN). In comparison to NVP@C, the electrochemical properties of NVP@C/GN, NVP@C/CNTs, and NVP@C/GN/CNTs have shown improvements. Among these, NVP@C/GN/CNTs exhibit the most outstanding electrochemical performance in the half-cell test. Specifically, this material demonstrates exceptional cycling stability, with a capacity of 92 mAh g⁻¹ that can be maintained even after 800 cycles at a high-rate performance of 10C, with an attenuation of 10.6 %. The enhanced electrochemical performance is attributed to the specific ternary carbon-coating conductive structure, which significantly shortens the diffusion paths of Na⁺ ions and electrons within NVP, resulting in improved Na⁺ ion and electron transport kinetics. This study provides a new design paradigm for improving the conductivity of cathode material for sodium-ion batteries.