Short-Range Ordered Porous Carbon Derived from Confined-Region Activation Strategy Exhibits Excellent High-Loading Performance in Supercapacitors

Constructing high-loading (>10 mg/cm2) carbon-based electrode materials is an effective way to simultaneously boost the gravimetric/volumetric energy density and power density of capacitors. However, porous carbon materials usually have high defect structures, low compaction density, and low graphitization degree, which severely hinder their electron/ion transport rates at high mass loading, thereby deteriorating the electrochemical performance. Thus, we first propose to construct short-range ordered porous carbon materials with high compaction density to enhance the detailed electrochemical performance without affecting the electron/ion transport rates. Herein, S, N codoped porous carbon (3SN-NAC-800) with a large specific surface area, high compaction density, and abundant short-range ordered structures was prepared by the confined-region activation method, in which needle coke was used as precursor, thiourea as the dopant, and KOH as the activator under 10 MPa pressure. The 3SN-NAC-800 electrode with 4 mg/cm2 exhibits high capacities of 267.2 and 229.7 F/g under 2 and 50 A/g, respectively, and 92.9% capacitance retention for 20,000 cycles. When the mass loading was increased to 8, 12, and 14 mg/cm2, it still exhibited high capacities of 260.4, 257.5, and 250.4 F/g at 2 A/g, respectively. Besides, the electrode with 12 mg/cm2 shows high gravimetric and areal capacitance values of 197.3 F/g and 2367.12 mF/cm2 at 40 A/g, respectively, as well as 90.98% capacity retention for 20,000 cycles, showing excellent rate capability and cycling stability. Furthermore, it exhibits a maximum energy density of 0.11 mWh/cm2 at 2.97 mW/cm2, and a maximum power density of 87.6 mW/cm2 at 0.044 mWh/cm2. This work demonstrates an efficient strategy to prepare short-range ordered porous carbon materials for high-mass-loading capacitors.