Nitrogen Doped Carbon Coated Bi Microspheres as High-performance Anode for Half and Full Sodium Ion Batteries.

As two-dimensional (2D) materials, bismuth (Bi) has large interlayer spacing along c-axis (0.395 nm) which provides rich active sites for sodium ions, thus guaranteeing high sodium ion storage activity. However, its poor electrical conductivity, combined with its degraded cycling performance, restricts its practical application. Herein, Bi microsphere coated with nitrogen-doped carbon (Bi@NC) was synthesized. Owing to the unique Bi crystals and nitrogen-doped carbon layer, the obtained Bi@NC anode exhibited satisfactory cycling stability and superior rate capability. Moreover, after assembling Bi@NC anode with Na3 V2 (PO4 )3 @C cathode to full battery, excellent sodium storage performance was obtained (57 mA h g-1 after 2000 cycles at 1.0 A g-1 ).