Simplified fast synthesis of strong-coupling composite supercapacitor materials by one-step bipolar pulse electrodeposition

Abstract

Combining two distinct materials to obtain high-performance electrode materials is a viable solution, but the process is inefficient, taking at least two processes and requiring tens of hours. Here, a unique bipolar pulse electrodeposition process is proposed, which effectively manufactures a composite electrode material with strong synergistic connection between NiCoS and PPy in a single step. Taking advantage of the synergistic impact of the nickel–cobalt sulfide nanoflower structure with a wide electrode–electrolyte contact area, as well as PPy with the appropriate thickness, the composite NiCoS/PPy electrode exhibits a high specific capacitance of 1848.8 F g⁻¹ at a current density of 1 A g⁻¹ and excellent rate performance. Due to the strong-coupling and the protection of the PPy layer, the electrode material possesses ultra-high cycling stability at high current density (96.15% capacitance retention after 10 000 cycles at 10 A g⁻¹). When compared to other typical methods, this approach greatly simplifies the composite electrode material production process, requiring just one step and 2400 seconds, which is hundreds of times faster. Furthermore, an assembled asymmetric supercapacitor (ASC) device of NCS/P-3//activated carbon (AC) achieves a high energy density of 48.79 and 40.21 W h kg⁻¹ at a power density of 750 and 7500 W kg⁻¹, respectively, while maintaining a long cycle-life. It is proved that on the premise of simplifying the preparation process by bipolar pulse electrodeposition, the composite electrode material has excellent electrochemical properties and can be used in high-capacity asymmetric supercapacitors.