Preparation and electrochemical properties of low-temperature activated porous carbon from coal tar pitch

Using coal tar pitch (CTP) as a carbon source and KOH as an activator, the one-step carbonization activation method was used to explore the effects of different activation temperatures on the development of the hierarchical porosity of carbon and its performance as electrodes in a supercapacitor. The results show that the specific surface area and pore volume of the prepared carbon material ACTP-3-600 at the activation temperature of 600 °C are higher than those at other temperatures, and the micropores account for about 90.5 %. When the mass ratio of KOH to CTP is 3, the specific capacitance of ACTP-3-600 can reach 475 F g−1 at a current density of 0.5 A g−1. Under the condition of a high current density of 10 A g−1, its specific capacitance can still maintain 301.8 F g−1, and the rate performance is 63.5 %. The symmetric supercapacitor assembled with it can achieve an energy density of 20.2 Wh kg−1 (at a power density of 450.0 W kg−1) in 1 M Na2SO4 electrolyte. After 10,000 cycles, the prepared carbon material has a capacitance retention rate of 91.2 % and good cycle stability. Because the activation temperature is relatively low, the method is simple, and the yield of prepared carbon material can reach 52.4 %, which is much higher than that of biomass (about 20 %). The prepared method can greatly reduce the cost of carbon materials. It is a feasible and helpful route to prepare high-performance hierarchical porous carbon materials.