Defect-rich phosphorus-doped 3D carbon cathodes with graphitic domains for high-performance zinc-ion storage devices

Aqueous zinc-ion capacitors (ZICs) have garnered significant attention as safe and cost-effective alternatives to lithium-ion batteries. However, conventional carbon cathodes suffer from limited Zn²⁺ adsorption capacity and sluggish charge transport, severely restricting their energy and power performance. Herein, we propose a scalable and cost-effective strategy to fabricate three-dimensional (3D) porous phosphorus-doped carbon (TPMC) with tunable graphitic domains, hierarchical porosity, and abundant active sites. The tailored microstructure features enlarged interlayer spacing, interconnected mesopores, and locally ordered graphitic regions, which together facilitate efficient Zn²⁺ diffusion and fast electron transport. Besides, phosphorus doping and silica template introduce surface and edge defects, further enhancing electrochemical activity. As a result, the optimized TPMC electrode delivers a high specific capacity of 257 mAh g^-1, an energy density of 244.1 Wh kg^-1 at a power density of 69.6 W kg^-1, and excellent cycling stability with 94.9 % retention after 100,000 cycles. Both kinetic analysis and ex situ characterizations confirm that graphite domain modulation significantly accelerates interfacial charge transfer and enhances pseudocapacitive behavior, thereby promoting Zn²⁺ adsorption/desorption. Moreover, the quasi-solid-state ZICs demonstrate high capacity, outstanding cycling stability with 95 % retention over 50,000 cycles, and excellent mechanical flexibility. This work provides new insights into the microstructural design of carbon materials and offers a promising strategy for developing advanced aqueous Zn-ion energy storage systems.