Ultrafast pore-tailoring of dense microporous carbon for high volumetric performance supercapacitors in organic electrolyte

Preparing activated carbon with high volumetric performance in organic electrolyte is crucial for developing high-energy and miniaturized supercapacitors, but still challenging because high surface area and large pore size are required to effectively store large-sized organic electrolyte ions, which usually result in the low density. Herein, an ultrafast strategy is proposed to tailor the interconnected porous structure of activated carbon through introducing CO₂ at the end of homogeneous activation. The uniformly distributed potassium components in carbon matrix promote a robust catalytic etching by CO₂, leading to precise tailoring of the ultramicropores (0.50–0.72 nm) to large micropores (0.81–1.14 nm) within only 2 min. The optimized sample with both high surface area and compaction density (2147 m² g⁻¹, 0.68 g cm⁻³) shows high gravimetric and volumetric capacitances (155 F g⁻¹ and 106 F cm⁻³ at 1 A g⁻¹) as well as good rate performance (102 F g⁻¹ and 70 F cm⁻³ at 20 A g⁻¹) in organic electrolyte. The symmetric supercapacitor achieves high energy densities of 35 Wh kg⁻¹ and 24 Wh L⁻¹ at 573 W kg⁻¹ and 395 W L⁻¹, respectively, indicating great potential of the ultrafast tailoring strategy for practical application.