Interlaminar oxygen bridging assisted alkali activation constructs hydrophilic petroleum coke-based porous carbon for advanced aqueous supercapacitors

Porous carbon with well-developed pores and heteroatom-doping is studied extensively in aqueous supercapacitor. However, few studies focus on the construction of hydrophilic capacitive carbon. Herein, interlaminar oxygen bridging assisted alkali activation strategy is proposed to design hydrophilic petroleum coke-based porous carbon (PPC) with oxygen-doping and pore forming via KOH activation oxidized petroleum coke. Due to the low activation temperature and alkali-coke ratio of 1:1, PPC-600 inherits high oxygen content of 14.51 at.% and ordered graphite lattice, and presents low specific surface area of 216 m 2 g −1 and small water contact angle of 6.2°. Electrochemical tests show that PPC-600 delivers a capacitance of 304.7 F g −1 at 0.5 A g −1 higher than PPC-700 (specific surface area of 1030 m 2 g −1 ) about 226.9 F g −1 . CV deconvolution reveals that the high capacitance of PPC-600 is associated with the coupling of surface-controlled and diffusion-controlled, while PPC-700 is mainly contributed by surface-controlled, confirming that interlaminar oxygen can increase the non-double layer capacitances. Furthermore, PPC-600-based aqueous supercapacitor has excellent capacitance retention of 89.7 % and Colombian efficiency about 100 % over 50,000 cycles at 10 A g −1 . These results show that surface heteroatom and hydrophilic engineering are promising strategies to improve the capacitance of porous carbon.