Hard–soft carbon decorated Na3V2(PO4)3 cathode for high-rate and stable sodium-ion batteries

Abstract

Na superionic conductors (NASICONs) have attracted much attention due to their unique framework structure and high capacity. However, the poor intrinsic electron conductivity severely limits further development. This work develops a soft–hard carbon composite modified Na₃V₂(PO₄)₃ (NVP) cathode with excellent rate performance and long-term cycling stability. The optimized sample exhibits excellent electrochemical performance and can deliver a specific discharge capacity of 102.7 mAh g⁻¹ at 1 C rate. At the same time, after 5000 cycles at 20 C rate, the discharge capacity can reach 82.3 mAh g⁻¹, and the capacity retention rate is 100.1%. The morphological characteristics of the NVP/C samples were investigated. Meanwhile, combined with Raman spectroscopy and electrochemical analysis, these results revealed that the synergistic interaction between soft and hard carbon components significantly enhances electronic conductivity and facilitates rapid ionic transport. This work provides a unique idea for the surface modification and synthesis of NASICON cathode materials for sodium-ion batteries.