Serving as conductive matrix and stress buffer, the carbon matrix plays a pivotal role in enabling red phosphorus to be a promising anode material for high capacity lithium ion batteries and sodium ion batteries. In this paper, nitrogen-doping is proved to effective enhance the interface interaction between carbon and red phosphorus. In detail, the adsorption energy between phosphorus atoms and oxygen-containing functional groups on the carbon is significantly reduced by nitrogen doping, as verified by X-ray photoelectron spectroscopy. The adsorption mechanisms are further revealed on the basis of DFT (the first density functional theory) calculations. The RPNC (red phosphorus/nitrogen-doped carbon composite) material shows higher cycling stability and higher capacity than that of RPC (red phosphorus/carbon composite) anode. After 100 cycles, the RPNC still keeps discharge capacity of 1453 mAh g-1 at the current density of 300 mA g-1 (the discharge capacity of RPC after 100 cycles is 1348 mAh g-1). Even at 1200 mA g-1, the RPNC composite still delivers a capacity of 1178 mAh g-1. This work provides insight information about the interface interactions between composite materials, as well as new technology develops high performance phosphorus based anode materials.
Keywords: anode materials; lithium ion batteries; nitrogen-doped carbon; red phosphorous.