Surface reconstruction of Co3O4/rGO heterointerface enabling high-performance asymmetric supercapacitors

Abstract

The rational surface reconstruction of component heterointerfaces is an effective strategy for boosting the electrochemical activity and structural stability of asymmetric supercapacitors. In this study, a Co₃O₄/rGO (cobalt oxide/reduced graphene oxide(rGO)) heterostructure was designed using a hydrothermal and annealing strategy. Owing to its abundant electroactive sites, accelerated diffusion reaction kinetics, and strong OH⁻adsorption capability, the optimized Co₃O₄/rGO composite delivered an ultrahigh capacitance of 273.3 F/g at 1 A/g. Additionally, density functional theory (DFT) calculations verified the significant charge transfer from Co₃O₄ to rGO near the heterointerface, achieving obvious charge redistribution and the formation of a space-charge layer. This optimization enhances significantly optimizes OH⁻ adsorption and diffusion and improves electrical conductivity, leading to the excellent electrochemical performance of the surface-reconstructed Co₃O₄/rGO. More importantly, the all-solid-state asymmetric supercapacitor Co₃O₄/rGO//AC (activated carbon) demonstrated an exceptional energy density of 16.47 Wh/kg at a power density of 599 W/kg, along with excellent cycling stability, retaining 91.0 % capacitance after 5000 cycles. Overall, this study provides an effective approach for designing surface-reconstructed heterointerfaces to achieve remarkable electrochemical performance and ensure structural integrity, showcasing significant potential for practical applications in the energy storage market.