Ultrafine Na3V2(PO4)3@C nanoparticles embedded in boron-doped graphene as high-rate and long cycle-life cathode material for sodium-ion batteries

Sodium-ion batteries have been regarded as the most attractive alternative to lithium-ion batteries because of their low cost, abundance of sodium resources and promising applications for energy storage systems. In this work, boron-doped graphene decorated Na3V2(PO4)3@C (BG-Na3V2(PO4)3@C) composite is successfully synthesized for the first time by using a simple sol-gel assisted solid-state method. In this composite, the ultrafine Na3V2(PO4)3@C particles are uniformly distributed on the boron-doped graphene sheets. The carbon layer and boron-doped graphene greatly increase the electron/ion transport kinetics of Na3V2(PO4)3 and assure the material structure integrity, leading to excellent electrochemical performances in terms of high-rate capability and long cycle-life. It delivers a high reversible capacity of 94.7 mAh g−1 at 10C and keeps 96.4% of the capacity after 100 cycles. These preliminary results reveal that the as-fabricated BG-Na3V2(PO4)3@C composite is a new promising cathode material for sodium energy storage.