Synthesizing mesoporous carbon with small pore size, narrow distribution and enhanced capacitive performance

Engineering porous carbon with small mesopores and narrow pore distribution is an effective strategy to trade-off the capacitive performances and pore structure of carbon materials. Here, mesoporous carbon with small pore size and bimodal distribution is successfully constructed from the mixture of coal tar pitch and agar via one-pot pyrolysis method in molten salt (KCl/KHCO 3 ). The formation process of bimodal pore structure is unveiled. During pyrolysis process, the agar with rich oxygen-containing groups generates abundant free radicals, which can not only accelerate the cross-linking reaction rate of pitch molecules to construct the carbon sketch, but also introduce oxygen-containing functional groups between carbon layers to effectively prevent the stacking effect of carbon. Therefore, the diffusion of molten KCl/K 2 CO 3 into the interior of the carbon layer is facilitated to achieve homogeneous activation to form bimodal pore structure. In three-electrode testing system, the optimized carbon shows superior rate capability with a specific capacitance of 220.0 F g −1 at 200.0 A g −1 in 6.0 mol L −1 KOH electrolyte. In two-electrode system, the capacitors in 1.0 mol L −1 TEABF 4 /acetonitrile achieves maximal energy density of 44.6 Wh kg −1 and power density of 34,000 W kg −1 . This work supplies a facile strategy to prepare small-sized mesoporous carbon material with high capacitive performances.