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.