Nitrogen-doped and partially graphitized coal-based hard carbon materials for high-performance sodium-ion storage in SIBs

Nitrogen-doped and partially graphitised coal-based hard carbons (NHCs) were prepared by a simple annealing process. NHC-2 exhibited a reversible capacity of 291.45 mAh g −1 at 0.03 A g −1 , a high ICE of 88.1%, and good cycling stability in SIBs.