Na 3 V 2 ( PO 4 ) 3 /C composites as low‐cost and high‐performance cathode materials for sodium‐ion batteries

Summary The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronic conductivity of Na 3 V 2 (PO 4 ) 3 . Based on this, Na 3 V 2 (PO 4 ) 3 /C composites with diverse ratios of citric acid are synthetized via rheological phase reaction way in this work. The consequences display that the Na 3 V 2 (PO 4 ) 3 /C‐1.5 composite brings a higher initial discharge capacity of 113.2 mAh g −1 at a current rate of 1 C with coulombic efficiency above 99% during all cycles. The discharge capacity retains at 117.6 mAh g −1 at the 100th cycle. Even at the high current densities of 5 C and 10 C, the composite also shows superior cycling performance with negligible capacity fading. Its discharge capacities decline from 97 to 92.6 mAh g −1 at 5 C and from 85.3 to 83.7 mAh g −1 at 10 C. These remarkable outcomes arise from its preferable morphology with suitable carbon coating because both excess and skimpy carbon seriously affect the microstructure and electrochemical properties of Na 3 V 2 (PO 4 ) 3 /C composites.