Optimized mesopores enable enhanced capacitance of electrochemical capacitors using ultrahigh surface area carbon...

Porous carbons with high specific surface area are critical engineering materials for current electrochemical capacitors (ECs) technology. Controlling the pore size distribution of porous carbons remains a significant challenge as it is a key aspect in many applications. Herein, we synthesized porous carbon as the electrode material of ECs by means of a two-step synthesis procedure using abandoned feathers as carbon precursor and potassium hydroxide as activating agent. The optimal sample (AFHPC-800-1:3) exhibited an ultra-high specific surface area (S_BET) of 3474 m²/g and a huge total pore volume (V_T) of 1.82 m³ g^-1 as well as abundant small mesopores ranging from 2 to 5 nm in size. The ECs based on the AFHPC-800-1:3 electrode exhibited an ultra-high specific capacitance (C_sp) of up to 709F g^-1 at 0.5 A g^-1. More interestingly, a capacitance of 212F g^-1 was retained even at 100 A g^-1, demonstrating excellent high-rate capacitive performance. Furthermore, the symmetrical capacitor yielded an excellent energy density of 35.1 Wh kg^-1 when the specific power density was 625 W kg^-1, substantiating the potential of the small mesopores in promoting the overall capacitance and energy density of electrode materials.