Preparation and capacitance performance of NiCo layered double hydroxide by multi-step constant current electrodeposition method

In comparison with single-step electrodeposition, multi-step electrodeposition for electrode preparation is more effective in releasing internal stresses, utilizing the highly efficient deposition time at the beginning of the electrodeposition, improving deposition efficiency, and producing adhesive-free high-performance electrodes with controllable mass. In this paper, NiCo layered double hydroxide (NiCo-LDH) with similar mass was successfully deposited by a two-electrode constant-current electrodeposition method using nickel foam as the substrate through different electrodeposition steps. A comparative study was conducted on the effects of NiCo-LDH deposition steps on the morphology, total deposition time, and electrochemical performance of NiCo-LDH samples. The results show that the mass of NiCo-LDH grown on foam nickel is similar when the number of deposition steps is from 1 to 6 at 12-13 mg, the coating of foam nickel substrate became more uniform. The total deposition time has decreased from 2550s for 1-step deposition to 1542 s for 6-step deposition, reducing the occupation time of the electrodeposition equipment. As the number of deposition layers increases, the specific capacitance of NiCo-LDH shows a trend of first increasing and then stabilizing. The high mass specific capacitance of NiCo-LDH electrode material deposited in 6 steps is 953 F g−1 at a current density of 3 mA cm−2. The assembled asymmetric supercapacitor device achieved an energy density of 0.309 mWh cm−2 at a power density of 4.25 mW cm−2, and a capacitance retention rate of 94 % after 10000 cycles at a current density of 40 mA cm−2. This indicates that the NiCo-LDH material prepared by multi-step electrodeposition method has good capacitance performance, providing a simple and time-saving method for manufacturing large-scale multi-step electrodeposition of adhesive-free supercapacitor electrodes.