A High-Concentration Edge-Nitrogen-Doped Porous Carbon Anode via Template Free Strategy for High-Performance Potassium-Ion Hybrid Capacitors

Developing facile and economical strategies to fabricate nitrogen-doped porous carbon anode is desirable for dual-carbon potassium ion hybrid capacitors (PIHCs). Here, a high-concentration edge-nitrogen-doped porous carbon (NPC) anode is synthesized by a template-free strategy, in which the total content of pyrrolic nitrogen and pyridinic nitrogen accounts for more than 80% of the nitrogen atoms. As a result, the NPC anode displays a capacity of 315.4 mA h g⁻¹ at a current rate of 0.1 A g⁻¹ and 189.1 mA h g⁻¹ at 5 A g⁻¹. Ex situ characterizations and density functional theory calculations demonstrate the high-concentration edge-nitrogen doping enhances K⁺ adsorption and electronic conductivity of carbon materials, resulting in good electrochemical performance. The assembled NPC//CMK-3 PIHC delivers an energy density of 71.1 W h kg⁻¹ at a power density of 771.9 W kg⁻¹ over 8,000 cycles.