A hollow core–shell MnO2-NT/NiMn-LDH/NiS electrode for enhanced supercapacitor performance

Abstract

Addressing the global energy crisis and the intermittency of renewables requires efficient electrochemical energy storage. Supercapacitors (SCs) deliver high power density, fast charge/discharge, and excellent cycling, but their low energy density is a major challenge. Therefore, hierarchical core–shell hybrid electrodes are rationally designed to enhance SC electrochemical performance. In this work, we synthesized hollow MnO₂/NiMn-LDH/NiS core–shell electrodes by employing MnO₂ nanotubes as the backbone and NiMn-LDH/NiS nanosheets as the shell. The MnO₂ nanotubes effectively reduce internal resistance, alleviate agglomeration, and facilitate rapid electron transport, while the ultrathin NiMn-LDH/NiS nanosheets provide a large specific surface area and abundant electroactive sites, thereby improving electrolyte accessibility and promoting synergistic redox reactions. Benefiting from this design, the composite electrode achieves a high specific capacitance of 1246.5 F g⁻¹ at 1 A g⁻¹, maintains 512.3 F g⁻¹ at 20 A g⁻¹, and preserves 91.2% of its capacitance after 1000 cycles. Furthermore, in a two-electrode asymmetric configuration, the device delivers an energy density of 42.6 Wh kg⁻¹ at 800 W kg⁻¹, sufficient for stable LED illumination. These results demonstrate the potential of hierarchical MnO₂/NiMn-LDH/NiS electrodes for high-performance energy storage applications.