Combustion activation synergistic self-templating approaches to construct N-doped honeycomb porous carbon anode for advanced potassium-ion batteries

Abstract

The development of high-performance anode materials for potassium-ion batteries remains challenging due to sluggish ion kinetics and structural instability. This study addresses these limitations by preparing nitrogen-doped honeycomb porous carbon (ESC-650) via a self-templated combustion activation strategy to enhance K⁺ storage, leveraging defect engineering and hierarchical porosity. Owing to the hierarchical pore structure with suitable N doping, ESC-650 exhibits satisfactory K⁺ storage performance. Specifically, ESC-650 can deliver a high reversible capacity of 321 mAh g⁻¹ at 0.05 A g⁻¹, retaining 89.1 % capacity after 250 cycles. Even at 10.0 A g⁻¹, ESC-650 can also maintain a capacity of 125 mAh g⁻¹, indicating that honeycomb porous carbon can be adapted to the rapid migration of K⁺, thus possessing favorable rate capability. In situ Raman analysis reveals there are two-state of K⁺ storage mechanism for ESC-650, which are surface adsorption and vacancy-adsorption accompanied by intercalation processes, respectively. Full-cell tests paired ESC-650 anode with K_0.45Mg_0.1Fe_0.1Mn_0.8O₂ cathode display a good cycling stability, which underscores ESC-650's potential for practical applications. This work establishes a defect-engineered, hierarchically porous carbon anode that overcomes kinetic barriers in PIBs. The synergistic integration of nitrogen doping and optimized pore architecture enables high-rate capability and long-term cyclability for carbon anode materials.