ABSTRACT The pursuit of high‐performance cathode materials is essential for advancing aqueous zinc‐ion hybrid capacitors (ZIHCs). However, conventional porous carbons often suffer from limited capacity and unsatisfactory rate capability due to insufficient active sites, mismatched pores, and low nitrogen‐doping levels. Herein, we propose a novel strategy for synthesizing nitrogen‐doped porous carbon (NPC) with a hierarchical pore structure using graphitic carbon nitride (g‐C 3 N 4 ) as a dual‐function soft template and nitrogen source and potassium citrate as a combined carbon precursor and activating agent. The optimal material, NPC‐0.5 (with a g‐C 3 N 4 /potassium citrate mass ratio of 1:3), exhibits a high specific surface area (805 m 2 g −1 ), a well‐defined hierarchical pore network, and a nitrogen content of 7.94 at% dominated by graphitic‐N species, which collectively enhance Zn 2+ storage and facilitate rapid ion transport. When employed as a cathode for ZIHCs, the NPC‐0.5 delivers a high specific capacity of 172 mAh g −1 at 0.1 A g −1 , excellent rate capability (41% capacity retention at 20 A g −1 ), and outstanding long‐term cycling stability (86% capacity retention after 65,000 cycles at 10 A g −1 ). This work provides an efficient and scalable approach for fabricating high‐performance nitrogen‐doped carbon cathodes for advanced ZIHCs.
Xu et al. (Sat,) studied this question.