Preparation of hierarchical porous activated carbons for high performance supercapacitors from coal gasification fine slag

Coal gasification is an important technology for clean conversion and utilization of coal. The coal gasification slag is the main solid waste of coal chemical industry, whose comprehensive utilization is an important factor for the whole coal chemical project to realize circular economy. In this work, coal gasification fine slag with high carbon content was used as the raw material to prepare hierarchical porous activated carbons (AC) after deep deashing. The optimal coal gasification fine slag activated carbon (GCFS-AC) has large BET surface area of 1151.8 m 2 /g and high total pore volume of 0.923 cm 3 /g. Owing to the hierarchical porous structures with large mesopore volume, CGFS-AC exhibits high charge storage capacity and energy density, as well as excellent cycling stability. The specific capacitance is 255.2 F/g at 1 A/g, which is significantly higher than that of commercial YP50 activated carbon. After 10,000 cycles, the specific capacitance is still 197.1 F/g, which is 94.4% of its initial capacitance. In addition, the CGFS-AC//CGFS-AC symmetric supercapacitor has a high energy density of 22.2 Wh/kg at power density of 399.8 W/kg.