Double carbon matrix rGO and resorcinol formaldehyde aerogel supported mesoporous K-⸹MnO2 nano-spheres as anode material for high efficacy hybrid aqueous asymmetric super capacitor

Abstract

The present study reports a high power density hybrid aqueous asymmetric super capacitor device by fabrication of potassium doped manganese oxide (K-⸹MnO₂) nano-spheres embedded in reduced graphene oxide (rGO) and resorcinol formaldehyde aerogel (RF) as anode material and activated carbon as cathode material. This rationally designed electrode material manifests exceptionally lofty areal capacitance of 1037.30 mF/Cm² and gravimetric capacitance 671.90 F/g. The synergy of reduced graphene oxide and resorcinol formaldehyde aerogel endows the K-⸹MnO₂ enhanced specific surface area (676.314 m²/g), elevated electroactive sites and improved ionic and electrical conductivity. Benefiting from Power law and Dunn's method a comprehensive mechanistic insight has been presented, revealing the superiority of surface controlled capacitive and pseudo-capacitive kinetics. In 1 M Na₂SO₄ electrolytic solution an asymmetric aqueous hybrid super capacitor rGO/K-⸹MnO₂/RF//AC has been fabricated. The device delivers an impressive areal cell capacitance of 321.63 mF/cm²and gravimetric cell capacitance of 371.25 F/g. Moreover the device exhibits excellent energy density 132 Wh/kg (114.35 μWh/cm²) and power density 533.33 W/Kg (4.6205 mW/cm²). The device shows outstanding cyclic stability of 96.7 % over 10,000 continuous charge-discharge cycles. This fascinating capacitive performance make the rGO/K-MnO₂/RF //AC a potent candidate for energy storage applications in hybrid aqueous asymmetric super capacitors.