Activator concentration regulating the porous structure of activated carbon for supercapacitor application

The porous structure and specific surface area (SSA) of activated carbon (AC) materials are two important factors to determine the performance of supercapacitors, and the emphasis in the current research is on how to regulate the pore structure of AC by an effective method. In this work, the low-cost and widely sourced semi-coke was employed to prepare AC in one step by the chemical activation method, which can effectively decrease the production cost of AC and promotes its application. Orthogonal experiments were designed to reveal the effect of process parameters on the electrochemical performance. It was found that the activator concentration has an important effect on the pore structure. When the mass ratio of the activator to semi-coke (R _as) remained unchanged, the large heating rate would result in a high activator concentration that delivered stronger etching power at the target temperature and thus remarkably affects the pore size and the pore volume of AC. When the heating rate changed from 2 to 7 ℃ min⁻¹, there had a considerable SSA increase of ca. 200 m² g⁻¹. To further reveal the effect of activator concentration on the pore’s property, the different mass ratios of the activator to semi-coke (R _as) were used. A series of ACs were produced, and the one that was prepared at 600 ℃ in a heating rate of 5 ℃ min⁻¹ in a R _as value of 3:1 delivered a high specific capacitance of 376 F g⁻¹ at 1 A g⁻¹ and a good cycling performance with a capacity retention of 98% after 10,000 cycles at 10 A g⁻¹. This work provided new inspiration for the preparation of high-performance activated carbon with low-cost semi-coke.