Investigations about the influence of different carbon matrixes on the electrochemical performance of Na3V2(PO4)3 cathode material for sodium ion batteries

Na superionic conductor (NASICON)–type Na3V2(PO4)3(NVP) has attracted great attention due to its unique conductive framework and high capacity. However, the poor intrinsic conductivity seriously restricted the further development. This work proposes an effective strategy of introducing the beneficial carbon-based matrix materials including reduced graphene oxide (rGO), polypyrrole (ppy), and carbon nanotubes (CNTs) to the NVP system. The modified composites reveal particular morphological features and enhanced specific surface areas, benefiting to improve the kinetic characteristics and sodium storage performance. Accordingly, the optimized NVP/C@CNT composite shows superior electrochemical performance. It can release a high reversible discharge capacity of 98.7 mAh g−1 at the 0.1 C rate. Meanwhile, a high capacity retention of 81% is obtained after 500 cycles at 2 C. Moreover, the kinetic characteristics demonstrate that the optimized NVP/C@CNT sample shows a high Na+ diffusion coefficient. This work offers a unique avenue for the development of the modification and synthesis of polyanion cathodes for sodium ion batteries. The modified samples combined with carbon-based matrix materials for the NVP system are successfully synthesized through a facile sol–gel method.