Studying the substrate effects on energy storage abilities of flexible battery supercapacitor hybrids based on nickel cobalt oxide and nickel cobalt oxide@nickel molybdenum oxide

Assembly of the efficient flexible energy storage devices is indispensable for widening the application of the wearable electronics which require electricity for operating. The flexible substrate such as Ni foam and carbon cloth is one of the key components for establishing flexible energy storage devices. However, the effects of the substrate for growing the active materials on the physical and electrochemical properties of the energy storage devices are rarely investigated. In this work, the Ni foam and the carbon cloth are used as the flexible substrates for fabricating the positive electrodes composed of the nickel cobalt oxide and the nickel cobalt oxide@nickel molybdenum oxide active materials for battery supercapacitor hybrids. The larger surface area and the pore volume are obtained for the electrodes based on the carbon cloth with the 360° growing sites, whereas the higher electrical conductivity and extra nickel hydroxide and nickel oxide are obtained for the electrodes based on the Ni foam. The best electrochemical performance is obtained for the battery supercapacitor hybrid based on the Ni foam substrate with the nickel cobalt oxide@nickel molybdenum oxide as the active material. This device provides the highest energy density of 11.90 Wh kg⁻¹ at the maximum power density of 800 W kg⁻¹. This work proposes a novel investigation of the substrate effect on the energy storage ability for the battery supercapacitor hybrids. The unique physical properties of the electrodes composed of the Ni foam and carbon cloth flexible substrates are also understood. Another feasible ways are expected to apply for improving the energy storage ability of the battery supercapacitor hybrids with the understanding of the flexible substrate features.