Novel electrochemical deposition of Co(CO3)0.5(OH)∙0.11H2O nano-needles with folded umbrella-like architecture onto nickel foam for supercapacitors

Here, we developed a novel anodic hydrothermal electrochemical deposition technology capable of directly growing a film of Co(CO3)0.5(OH)∙0.11H2O∙0.11H2O onto nickel foam for supercapacitors. The resultant film exhibited a morphology of nano-needles with folded umbrella-like architecture, different from the smooth needle-like morphology in reported articles, and could deliver a specific capacitance of 2.455 F·cm−2 (1227F·g−1) at 5 mA∙cm−2, a rate capability of 58.9% after a 6 fold increase in the charge/discharge current density and a capacity retention of 93.7% after 10,000 cycles in a three-electrode electrolytic cell. When packaged as a two-electrode asymmetric supercapacitor (ASC) device with the Co(CO3)0.5(OH)∙0.11H2O film electrode as the positive electrode and active‑carbon as the positive electrode, the ASC device exhibited specific capacitances of 1.46(112.3), 1.38(106.2), 1.36(104.6), 1.25(96.2) and 1.11 F·cm−2 (85.4 F·g−1) at 5, 8, 10, 20 and 30 mA∙cm−2, and the capacitance retention rate of 72.9% after 10,000 cycles at 8 mA∙cm−2. The results demonstrate the potential of anodic hydrothermal electrochemical deposition in fabricating the film of active electrode materials on conductive substrates for next-generation supercapacitor with high performance. •Anodic hydrothermal electrochemical deposition was developed to prepare a film electrode for supercapactiors.•Co(CO3)0.5(OH)∙0.11H2O exhibited a morphology of nano-needles with folded umbrella-like architecture.•The resultant film electrode delivered superior electrochemical performance.