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

Abstract

Hard carbon materials are widely regarded as highly promising anode materials in sodium-ion batteries (SIBs) due to their distinctive disordered structure and high capacity. However, their practical applications are greatly limited due to their high cost, low conductivity and unsatisfactory sodium storage performances. In this work, we propose a cost-effective method for the preparation of nitrogen-doped and partially graphitized coal-based hard carbons (NHCs) as high-performance anode materials for SIBs. The resulting NHCs possess the structural advantages of a mesoporous structure, nitrogen doping, and homogeneous graphite domains, which facilitate rapid kinetics and electron transfer. When applied to anodes in SIBs, the NHCs delivered a high reversible capacity of 291.45 mAh g⁻¹, a high initial coulombic efficiency of 88.1%, and an impressive cycling stability of 132.7 mAh g⁻¹ even after 500 cycles at 1 A g⁻¹. Overall, the coal-based hard carbon materials prepared using this straightforward yet effective method have the potential for large-scale energy-related applications in terms of economical precursors, simple synthesis process and excellent storage-energy performances.