Enhanced supercapacitor performance by fabricating open-porous MnCo2O4 particles on carbon cloth and using K3[Fe(CN)6] electrolyte additive

In the pursuit of advanced energy storage solutions, materials featuring high porosity, robust redox activity, and abundant electrochemically accessible sites are highly attractive candidates for next-generation supercapacitor electrodes. In this study, a binder-free positive electrode material consisting of porous MnCo 2 O 4 particles directly coated onto carbon cloth (MnCo 2 O 4 @CC) was synthesized via a straightforward hydrothermal process followed by thermal treatment. Additionally, the incorporation of redox additives into electrolytes has been identified as a promising approach to elevate electrochemical supercapacitor performance. To this end, we designed an aqueous asymmetric supercapacitor (ASC) system utilizing MnCo 2 O 4 @CC and activated carbon (AC) electrodes, where potassium ferricyanide (K 3 [Fe(CN) 6 ], denoted as KFCN) was introduced as an electrolyte additive to augment pseudocapacitive behavior. The electron migration mechanisms and charge storage dynamics of MnCo 2 O 4 @CC in a KOH + KFCN electrolyte were systematically investigated. The MnCo 2 O 4 @CC electrode immersed in a 3 M KOH + 0.05 M KFCN solution exhibited a high specific capacitance of 2206.7 F g −1 at 1 A g −1 , along with low resistance characteristics and exceptional cycling durability. A complete aqueous MnCo 2 O 4 @CC//KOH + KFCN//AC ASC was assembled, demonstrating enhanced specific capacitance, extended cycle life (94.5% capacitance retention after 10,000 cycles), and an ultrahigh energy density of 79.9 Wh kg −1 at 799.6 W kg −1 . These findings provide significant electrochemical insights and demonstrate the great potential of the MnCo 2 O 4 @CC-KOH + KFCN system for next-generation supercapacitor applications.