Russian‐Doll‐Like Porous Carbon as Anode Materials for High‐Performance Potassium‐Ion Hybrid Capacitors

Abstract Pore‐structure design with the sophisticated and pragmatic nanostructures still remains a great challenge. In this work, porous carbon with Russian‐doll‐like pores rather than traditional single modal is fabricated via a boiling carbonization approach, accompanied by K⁺‐pre‐intercalation. The most important internal factor is that alkali can penetrate into the stereoscopic space of layered Malonic acid dihydrazide and the confinement effect leads to the in‐depth development of different dimensional pore structures. The oxygenated and nitrogenated surface guarantees the K⁺ intercalation behavior. Benefiting from their open framework and enlarged interlayer spacing, K⁺‐pre‐intercalated porous carbon with Russian‐doll‐like pores (denoted as KPCRPs) as anode material exhibits promising potassium storage performance. The assembled KPCRP//activated carbon potassium‐ion hybrid supercapacitor in 30 m CH₃COOK displays a high energy density of 157.29 Wh kg⁻¹, an ultrahigh power output of 14 kW kg⁻¹, and a long cycling life (99.58% capacity retention after 10000 cycles), highlighting the superiority of Russian‐doll‐like pore structure. This work sheds light on the designing of 3D pores structure, especially for multimodal pore architectures.