High Nitrogen-Doped Carbon Nanorings Derived from Coal Tar Pitch with Surfactant-Mediated Self-Assembly Strategy for Enhanced Zinc-Ion Storage

Zinc-ion hybrid capacitors (ZIHCs) are poised to make a significant impact on the energy storage domain, yet their progress is impeded by the limited number of active sites in existing carbon electrode materials. In this paper, surfactant-mediated electrostatic self-assembly and confined pyrolysis strategy are employed to fabricated nitrogen-doped carbon nanorings (NCNRs) with coal tar pitch as the carbon precursor and g-C3N4 nanorings (g-CNNRs) as both template and nitrogen source. The as-prepared NCNRs possess thin-walled hollow nanostructures with high nitrogen-doping content (∼15 atom %) and a high density of defects (sp3/sp2=0.73). When employed as the positive electrode in ZIHCs, the NCNRs exhibit a high reversible capacity (249 F g–1 at 0.1 A g–1), excellent rate performance (113 F g–1 even at 20.0 A g–1), and ultralong cycle life (90% capacity retention after 20,000 cycles at 1.0 A g–1). This work presents a strategy for the design of novel-structured carbon materials from coal tar pitch toward high-performance ZIHCs.