Preparation and characterization of high performance super activated carbon based on coupled coal/sargassum precursors

High electrochemical performance supercapacitors require activated carbon with high specific surface area, suitable pore size distribution and surface properties, and high electrical conductivity as electrode materials, whereas there exists a trade-off relationship between specific surface area and electrical conductivity, which is not well met by a single type of carbon source. To solve this problem, the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution, followed by carbonization and KOH activation. The effects of mixing mass ratio and activation temperature on the prepared activated carbon (AC) are investigated using single factor experimental method. The experimental results show that AC 1/3-800 has abundant micropore and mesopore content, good pore structure connectivity, high electrical conductivity and good wettability, and superior electrochemical properties compared with other activated carbons prepared in this experiment. Its total specific surface area is up to 2098.5 m 2 ·g −1 , the pore volume is up to 1.33 cm 3 ·g −1 , the content of mespores with diameter of 6–8 nm is significantly increased, and the pore size distribution is wide and uniform. When the current density increases from 0.1 to 10 A·g −1 , the gravimetric capacitance decreases from 219 to 186 F·g −1 with a capacitance retention of 84.9%, the equivalent series resistance is very small, and the rate performance and reversibility of charging and discharging have also been excellent.