The supercapacitor performance of heteroatom doped activated carbon produced from biomass

As a result of the increase in energy demand, the development of clean, sustainable and effective energy storage and conversion technologies is one of the most popular fields of study of the world's science and technology communities. Among the different energy storage systems, supercapacitors stand out thanks to their features. In this study, activated carbon produced from vetch seeds (VSAC) was used as supercapacitor electrode material. In the first step, different carbonisation temperatures and activation chemical ratios were investigated and the activated carbon samples with the highest and lowest electrochemical performance were determined. Activated carbon (VSAC 600-800 IR3) has the highest specific capacitance values with a carbonisation temperature of 600 °C and an activation chemical impregnation ratio of 1:3 by mass (carbonised sample: KOH). These specific capacitance values have been calculated as 248 F/g in 1 M H2SO4 electrolyte and 167 F/g in 6 M KOH electrolyte, respectively. On the other side (VSAC 650-800 IR1) has the lowest specific capacitance values with the carbonisation temperature of 650 °C and an activation chemical impregnation ratio of 1:1 by mass (carbonised sample: KOH). These specific capacitance values have been calculated as 92 F/g in 1 M H2SO4 electrolyte and 106 F/g in 6 M KOH electrolyte. In the second step, nitrogen-sulphur co-doping and boron doping processes were carried out for both samples. Electrochemical performances of the samples produced as a result of heteroatom doping were investigated in 1 M H2SO4 and 6 M KOH electrolytes. As a result of these processes, the highest increase in the specific capacitance value was observed in the activated carbon coded by VSAC 650-800 IR1 B. The results of the electrochemical performance analyses performed using 1 M H2SO4 and 6 M KOH electrolytes were calculated as 307 F/g (233 % increase) and 169 F/g (60 % increase), respectively. In the light of all these data, it has been proven that high performance supercapacitor electrode material can be obtained by producing activated carbon from vetch seeds at a certain pre-carbonization temperature and activation chemical ratio.