Synthesis and electrochemical performance of ultrafine hierarchical S-doped MnNi LDH-MWCNTs as highly efficient hybrid cathode for flexible asymmetric supercapacitors

The present work proposes a novel hierarchical nanostructure composed of the Cu-Ni nanostructured metallic foams (CN NMFs) and S-doped MnNi LDH-MWCNTs on Cu foil (CF), as an excellent self-standing hybrid cathode for flexible asymmetric supercapacitors. The combination of structural and compositional advantages endows the CF/CN NMFs/S-LDH-MWCNTs electrode with greatly improved electrochemical capacitive performance, including high specific capacitance (4760 F g–1 at a current density of 1 A g–1) and excellent rate capability (81.9% capacitance retention at 10 A g–1) and superior cycling stability. Remarkably, the corresponding solid-state flexible asymmetric supercapacitor with CF/CN NMFs/S-LDH-MWCNTs and Fe3O4@ZnO-AC film as cathode and anode, respectively, delivers a high energy density up to 124.37 Wh kg–1 as well as superb cycling stability (98.8% capacitance retention after 5000 cycles), and can be able to light up a LED indicator, demonstrating the potential for practical applications. These attractive results suggest that such an all-solid-state asymmetric supercapacitor shows great potential in developing energy storage systems with high levels of energy and power delivery.