Influence of structure directing agents on synthesizing battery-type materials for flexible battery supercapacitor hybrids

Abstract Nickel cobalt oxide with the high theoretical capacitance and abundant redox states is considered to be one of the most effective energy storage materials for battery supercapacitor hybrids. Morphology design is well adopted for improving the energy storage ability of active materials. Morphology of active materials are reported to be largely influenced by the structure directing agents, but the effects of structure directing agent on physical and electrochemical properties of active materials are rarely discussed. In this work, urea, hexamethylenetetramine and ammonium fluoride are utilized as structure directing agents to synthesize nickel cobalt oxide and nickel cobalt oxide/nickel molybdenum oxide nanostructures on the nickel foam and the carbon cloth as the battery-type electrode for battery supercapacitor hybrids. The surface area and pore volume for active materials play dominated roles on the electrocapacitive performance of resulting battery supercapacitor hybrids, whereas surface properties effects on the electrochemical performance are limited when the surface area and pore volume of the active materials are large enough. This work fairly investigates the structure directing agent effects based on different active materials and flexible substrates. The discussion on the relation of surface and resistance features to the electrocapacitive performance of battery supercapacitor hybrids is also well established in this work.