NaTi₂(PO₄)₃@C nanocrystals anchored on B-doped graphene sheets with outstanding electrochemical performances for sodium energy storage

NASICON-type NaTi2(PO4)(3) (NTPO) is a promising anode for Na+ batteries owing to its excellent thermal stability, high Na+ conductivity, high theoretical capacity, low price, and good safety. However, the electronic conductivity of NTPO is not satisfactory for practical applications in rechargeable Na+ batteries. In this work, NTPO@C electrode anchored to B-doped graphene (BG) sheets is synthesized via a combination of facile sol-gel procedure and solid-state reaction at high temperature. As envisioned in the design step, the BG coupled with the carbon layer forms a network that improves the electronic conductivity of BG/NTPO@C anode, resulting in excellent Na+ storage properties. It provides a high specific capacity of 127.9 mAh g(-1) at 0.1C in the potential range of 1.5-3.0 V. Furthermore, it displays a high reversible capacity of 103.4 mAh g(-1) at 10C over 500 cycles while retaining 93.7% of the initial capacity. These electrochemical experiments demonstrate that the developed BG/NTPO@C composite is a promising novel anode for high-performance Na+ batteries.