A Facile Process to Make Phosphorus-doped Carbon Xerogel as Anode for Sodium Ion Batteries

Sodium ion batteries become popular due to their low cost. Among possible anode materials of sodium ion batteries, phosphorus has great potential owing to its high theoretical capacity. Previous research that yielded high capacity of phosphorus anode used very expensive materials such as black phosphorus (BP) and phosphorene. To take advantage of the low cost of sodium ion batteries, we proposed a new method to make anode: condensing red phosphorus (RP) on carbon xerogel. Even with large particle size (~ 50 $\mu$m) and high mass loading (2 mg/cm$^2$), the composite cycled at 200 mA/g yielded a capacity of 242 mA/g, or 1993 mAh/g based on phosphorus after subtracting the contribution of carbon. The average degradation rate is only 0.06% in 80 cycles. The average columbic efficiency is as high as 99.2%. Our research provided an innovative approach to synthesis of anodes for sodium ion batteries, which could promote their commercialization.