Small mesopore engineering of pitch-based porous carbons toward enhanced supercapacitor performance

The advancement of modern carbon-based supercapacitor depends strongly on the porous carbons (PCs) with tailoring pore configuration. To achieve the trade-off between power density and energy density, enriching small mesopore in PCs is an important but challenging research subject. Herein, the PCs with customizable small mesopores were fabricated from cheap coal tar pitch (CTP) by adjusting their content of light component (i.e. toluene soluble CTP, TS). The share of small mesopore in total pore structure of PCs (V2–4 nm/Vtotal) progressively increases with the lifting TS content of precursor. Consequently, the specific surface area and pore volume of PCs increase first and then decrease as the TS content increases. Simultaneously, the influence of small mesopore on the capacitance performances of supercapacitors was reflected in their capacitance, rate capability, cycle stability and self-discharge performance. The supercapacitor assembled by the PC with a V2–4 nm/Vtotal of ~31.3% delivers a superior energy density of 0.15 mW h cm−2 at a power density of 5.40 mW cm−2. Therefore, the small mesopore engineering in carbon materials derived from inexpensive precursors broadens the avenue to further improve the areal capacitive performance of supercapacitors by a facile up-scalable approach.