Na3V2(PO4)3@NC composite derived from polyaniline as cathode material for high-rate and ultralong-life sodium-ion batteries

Polyaniline-derived N-doped carbon-composited Na3V2(PO4)(3) (NVP@NC) are synthesized by a rheological phase reaction followed by calcination. The NVP@NC composite displays improved cycling and rate properties. Its discharge capacity remains 118.7 mAh g(-1) at the 400th cycle at 0.3 C. It also obtains invertible capacities of 93.7 and 91.1 mAh g(-1) at 5 and 10 C after 1000 cycles, with capacity retention rates of 92.7% and 98.4%, respectively. These enhanced results due to the N-doped carbon layer (NC), which restrains the expansion and deformation of the crystal structure, reduce the transport length of sodium ion and electrons and improves the electroconductibility of NVP.