Doable high energy density supercapacitors using rice husk-derived carbon in dihydroxybenzenes as redox-additive electrolytes

Abstract

Though activated carbon made from various bio wastes is quite affordable and plentiful, the energy density of these electrodes in aqueous electrolytes is still questionable. Therefore, increasing the energy density of activated carbon for use in supercapacitors is a challenging issue. The ideal way to boost the energy density of supercapacitors in aqueous electrolytes is by using redox-additive electrolytes. Redox-additive electrolytes are the impeccable solution for thriving the energy density of supercapacitors in aqueous electrolytes. Here, three additives namely 1, 2-benzene diol, 1, 3-benzene diol, and 1, 4-benzene diol were utilized as redox-additives with 1 M H2SO4 to study the influence of the position of OH on their redox activity and electrochemical performance. The activated carbon derived from rice-husk delivered a high specific capacitance of 1414 F/g at 4 A/g with 1, 4-benzene diol/H2SO4 among the three redox additives. A symmetric supercapacitor was fabricated, which exhibited a remarkable energy density of 38 Wh/kg at 2 A/g with 1, 4-benzene diol/H2SO4, which is almost 4 times superior to the energy density of the same electrode with H2SO4 (10.6 Wh/kg at 2 A/g).