Nitrogen-doped porous carbon microspheres for high-rate anode material in lithium-ion batteries

Developing high-capacity anode materials is urgent for next-generation lithium-ion batteries (LIBs) with the increasing need of larger scale applications. In order to obtain suitable anode materials, nitrogen-doped porous carbon microspheres (NPCMs) were prepared via spray drying followed by carbonization using chitosan as both carbon and nitrogen sources. The structure and properties of NPCMs were characterized by thermogravimetric, Raman spectroscopic, x-ray diffraction, scanning electron microscopic, transmission electron microscopic as well as x-ray photoelectron spectroscopic analysis, and the electrochemical performance of NPCM electrodes were also evaluated. The results show that the diameter of the obtained microspheres is 1-7 μm. When used as the anode material, the NPCMs display a reversible capacity of 443 mAh g^-1 at 100 mA g^-1 after 120 cycles and maintain a high capacity of 377 mAh g^-1 at 1 A g^-1 after 500 cycles. Even at a high current density of 4 A g^-1, a discharge capacity of 256 mAh g^-1 can also be obtained. The excellent rate performance and long cycle life of the electrode might be ascribed to the nitrogen-doping, porous and amorphous structure of NPCMs. The results suggest that the prepared NPCMs have the potential to be used as a promising anode material for high-capacity LIBs.