Integrating bimetallic MOF-derived sulfides with MnO2: synergistic Cu–Co–S@MnO2 heterojunctions for flexible hybrid supercapacitors

Abstract

Metal–organic frameworks (MOFs) are promising energy storage materials due to their high specific surface area and tunable structures. However, their practical application is limited by poor conductivity and structural stability. This study proposes a dual-strategy modification combining sulfidation and MnO₂ coating to address these issues. A bimetallic Cu–Co-MOF was grown on nickel foam via hydrothermal synthesis, followed by sulfidation to form Cu–Co–S, enhancing conductivity through electron structure optimization. Subsequent rapid electrodeposition of MnO₂ created a heterojunction structure, improving structural stability and forming an interfacial electric field to boost electron mobility and ion adsorption. The Cu–Co–S@MnO₂ electrode achieved a specific capacitance of 1483.3 F g⁻¹ at 1 A g⁻¹ and retained 93% capacitance after 10 000 cycles. A flexible asymmetric supercapacitor using this electrode retained 88.1% capacitance after 5000 cycles. Additionally, the device achieves an energy density of up to 185.25 Wh kg⁻¹ at high power density of 0.75 kW kg⁻¹. These results highlight the potential of this strategy for developing high-performance, durable energy storage devices for flexible electronics.