Citric acid-assisted synthesis of Na 3 V 2 (PO 4 ) 3 /C composite as high-performance electrode material for sodium-ion batteries

Na 3 V 2 (PO 4 ) 3 with NASICON structure is regarded as a hopeful cathode in sodium-ion batteries (NIBs). Nevertheless, the immanently inferior electronic conductivity significantly restricts its electrochemical performance and practical application. In this work, a facile solid-state sintering approach employing citric acid as both the reduction agent and carbon source has been developed to prepared Na 3 V 2 (PO 4 ) 3 /C composite. The influence of different sintering temperatures on the structure, morphology, and electrochemical performance of Na 3 V 2 (PO 4 ) 3 /C for NIBs was systematically investigated. The results indicate that the Na 3 V 2 (PO 4 ) 3 /C sample calcined at 850 °C (NVP/C-850) presents the best electrochemical property among the as-obtained four NVP/C samples studied. The optimized NVP/C-850 composite exhibits a reversible capacity of 117.4 mAh/g at 0.2 C, and after 100 cycles, capacity retention of 94.7% was kept. Besides, among the four electrodes, NVP/C-850 electrode exhibited smallest resistance and highest Na + diffusion coefficient. Thus, the outstanding results demonstrate potential application of the NVP/C for NIBs.