Boosting Zn-ion storage capacity of pitch coke-based activated carbon via pre-oxidation assisted KOH activation strategy

Abstract

Activated carbons (ACs) with unique structure are desired for high-performance of Zinc-ion supercapacitors (ZICs). Herein, a series of ACs were prepared using air pre-oxidation assisted KOH activation technology from pitch coke (PHC). The results show that pre-oxidation promotes the development of pore and the regulation of surface chemical composition of obtained ACs. Based on this experiment, the as-prepared AC-330 delivers suitable oxygen functional groups, high specific surface area of 3223 m 2 g −1 and high small-sized mesopore (2–4 nm) volume of 0.72 cm 3 g −1 . All these unique structures endow AC-330 with a satisfactory specific capacity of 212.5 mAh g −1 at 0.1 A g −1 , and it can still remain at 85 mAh g −1 even when the current density increased up to 20 A g −1 with an excellent capacity retention of 40%. Fortunately, it can also deliver high energy-power density parameters (170 Wh kg −1 at 170.4 W kg −1 and 67.2 Wh kg −1 at 32.3 kW kg −1 ). • Pitch coke-based porous carbon (AC) was obtained via pre-oxidation assisted KOH activation. • The obtained AC has well-developed mesoporous structure for rapid ion transport. • Ion diffusion coefficient as a function of V 2–4 nm /V mic ratio was investigated. • The maximum energy density and power output of ZICs are 170 Wh/kg and 32.3 kW kg −1 , respectively.