Nitrogen self-doped carbon with super high-rate and long cycle life as anode materials for lithium-ion batteries

Nitrogen self-doped carbon was synthesized by hydrothermal and microwave calcination using polyacrylonitrile as a carbon source and nitrogen source. This method dramatically reduces the material preparation time while improving the electrochemical performance of amorphous carbon. X-ray photoelectron spectroscopy (XPS) analyses reveal that the pyridine nitrogen content is increased and the graphitized nitrogen disappeared in an amorphous carbon block. This indicates that the nitrogen doping sites of the amorphous carbon block can be modulated by the hydrothermal method. Microscopic observations show that the nitrogen self-doped carbon is nano-carbon spheres and carbon micron block. The self-doped nitrogen micron carbon block exhibits excellent cyclability and ultra-high rate capacity. When cycled at 0.5 A g⁻¹, the discharge capacity remains 356.6 mA h g⁻¹ after 1000 cycles. Even cycled at 5 A g⁻¹, the rate capacity was maintained at 183.3 mA h g⁻¹ after 300 cycles. The defects produced by self-doped pyridine nitrogen, not only improved the reactivity and electronic conductivity but also enhanced lithium-ion diffusion kinetics.