Nitrogen-rich Graphite Flake from Hemp as Anode Material for High Performance Lithium-ion Batteries

Biomass-derived carbon (BC) has attracted extensive attention as anode material for lithium ion batteries (LiBs) due to its natural hierarchical porous structure and rich heteroatoms that can adsorb Li⁺ . However, the specific surface area of pure biomass carbon is generally small, so we can help NH₃ and inorganic acid produced by urea decomposition to strip biomass, improve its specific surface area and enrich nitrogen elements. The nitrogen-rich graphite flake obtained by the above treatment of hemp is named NGF. The product that has a high nitrogen content of 10.12% has a high specific surface area of 1151.1 m²  g^-1 . In the lithium ion battery test, the capacity of NGF is 806.6 mAh g^-1 at 30 mA g^-1 , which is twice than that of BC. NGF also showed excellent performance that is 429.2 mAh g^-1 under high current testing at 2000 mA g^-1 . The reaction process kinetics is analyzed and we found that the outstanding rate performance is attributed to the large-scale capacitance control. In addition, the results of the constant current intermittent titration test indicate that the diffusion coefficient of NGF is greater than that of BC. This work proposes a simple method of nitrogen-rich activated carbon, which has a significantly commercial prospect.