NaTi^sub 2^(PO^sub 4^)^sub 3^@C nanoparticles embedded in 2D sulfur-doped graphene sheets as high-performance anode materials for sodium energy storage

Na-ion battery has been investigated as a potential candidate for Li-ion battery because of its abundant sodium resource. One of the advanced anodes for Na-ion battery is NaTi2(PO4)3 due to the open 3D framework, good thermal structure and high Na+ conductivity. However, the NaTi2(PO4)3 material possesses a low electrical conductivity, which hinders its application for large-scale sodium storage. Herein, the nanosized NaTi2(PO4)3@C crystals embedded in 2D sulfur-doped graphene sheets are synthesized using a simple method. The 2D sulfur-doped graphene sheets can easily facilitate the transport of electrons/ions and inhibit the volume change during the insertion/extraction of Na+ ions, resulting in superior rate property. The synthesized electrode shows the high discharge capacity (130.1 mAh g−1 at 0.1 C), excellent rate property (112.8 mAh g−1 at 10 C) and stable cycle life (95.8 mAh g−1 over 500 cycles at 20 C), revealing its great application for Na-ion battery. This novel strategy could be applied to synthesize other advanced electrode materials for electrochemical sodium storage.