Carbon Nitride Transforms into a High Lithium Storage Capacity Nitrogen-Rich Carbon.

We describe here the metal-templated transformation of carbon nitride (CN) into nitrogen-containing carbons as anodes for Li-ion batteries (LIBs). Changing the template from the carbon- and nitrogen-immiscible Cu powder to the carbon- and nitrogen-miscible Fe powder yields different carbons; while Fe templating produces graphitized carbons of low (<10%) nitrogen content and moderate pore volume, Cu templating yields high defect-density carbons of high (32-24%) nitrogen content and larger pore volume. The Li storage capacity of the high nitrogen content and larger pore volume Cu-templated carbons exceeds that of the more graphitic Fe-templated carbons due to added contribution from Li insertion/extraction from pores and defects and to reversible faradaic Li reaction with nitrogen atoms. The Cu-templated carbon annealed at 750 °C delivers the highest specific capacity of 900 mAh g at 0.1 A g and 275 mAh g at 20 A g, while also achieving a 96% capacity retention after 2000 cycles at 2 A g. The fabrication of higher mass loading electrodes (4.5 mg cm) provided a maximum areal capacity of 2.6 mAh cm at 0.45 mA cm (0.1 A g), comparable to the capacities of commercial LIB cells and favorable compared to other reported carbon materials.