Regulation of nitrogen configurations and content in 3D porous carbons for improved lithium storage

Abstract

The incorporation of active nitrogen species in carbon materials has been widely demonstrated as a viable means to produce superior lithium storage materials, while the precise regulation of nitrogen configurations as well as their content still remains a formidable challenge. Herein, nitrogen-free porous carbon frameworks were synthesized by a self-templating strategy from disodium citrate, and post-annealing yielded 10.4 at% N that was primarily pyrrolic-N and pyridinic-N with an atomic ratio of about 3 : 1, with negligible inactive graphitic-N. A gravimetric capacity of 570 mA h g⁻¹ at a current density of 4 A g⁻¹ was measured for a Li half-cell based on the as-prepared N-doped 3D carbon materials. Lithium-ion capacitors with this N-doped carbon as the anode and commercial AC as the cathode yielded energy densities of 58.9 and 142.6 W h kg⁻¹ with the corresponding power densities of 7400 and 185 W kg⁻¹, respectively. We suggest that the carbon materials with high content of pyrrolic-N and pyridinic-N especially pyrrolic-N have improved lithium storage.