Nitrogen-doped chain-like carbon nanospheres with tunable interlayer distance for superior pseudocapacitance-dominated zinc- and potassium-ion storage

Carbon-based materials have attracted extensive interest in metal-ion batteries owing to their low cost, good conductivity, and environmental friendliness. The practical application of graphite materials is associated with trade-offs in cyclability and energy density due to the sluggish kinetics. Herein, nitrogen-doped chain-like carbon nanospheres (NCN) with expanded interlayer distance are effectively fabricated by annealing carbon derived from aniline combustion. More impressively, the resulting NCN exhibits a chain-like structure and pyrrolic-N-dominated nitrogen doping, which not only facilitates charge transport but also provides chemically active sites for Zn- and K-ion storage. The above features lead to ultrafast ion storage in the NCN electrode via redox pseudocapacitive reactions, which endows NCN with enhanced kinetics and dramatic electrochemical performance: a remarkable energy density of 124.1 W h kg⁻¹ for zinc-ion storage; superior reversible capacity (363.4 mA h g⁻¹ at 0.1 A g⁻¹), robust rate capability (120.3 mA h g⁻¹ at 10 A g⁻¹) and excellent cycling performance (193.8 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹) for potassium-ion storage.