Novel fabrication strategy of nanostructured NiCo-LDHs monolithic supercapacitor electrodes via inducing electrochemical in situ growth on etched nickel foams

• Ultra-fast electrochemical in-situ growth of NiCo-based hydroxides on nickel foams. • The in-situ grown NiCo-LDHs comprise rough and porous hierarchical nanosheets. • The Ni 1 Co 2 /NF electrode has a high specific capacity of 3.01 C cm −2 at 1 mA cm −2 . • The assembled HSC device has a high energy density of 97.4 μWh cm −2 at 800.5 μW cm −2 . • The assembled HSC device retains 85.0% of its initial capacity after 5000 cycles. Development of electrode materials with high electrochemical charge storage capabilities through cost-effective methods has attracted intensive attention from researchers. Herein, a low-cost and scaled-up method for electrochemical synthesis of monolithic electrodes is presented. Nickel foam (NF) was chemically etched using the transition metal (NiCo-based) nitrate solutions with different ratios of Ni and Co. After being rinsed and dried, the etched NF was used as anode in an alkaline solution and a Pt mesh was utilized as cathode. Shortly after a constant voltage was applied to the two-electrode system, NiCo-based layered double hydroxides (NiCo-LDHs) were found to be self-grown on the NF with an ultra-fast rate. The in situ grown NiCo-LDHs were composed of hierarchical nanosheets with rough and porous surfaces, and had a high specific area. The monolithic Ni 1 Co 2 /NF electrode exhibited the best electrochemical performance with a high specific capacity of 3.01 C cm −2 at 1 mA cm −2 . A hybrid supercapacitor was assembled using the Ni 1 Co 2 /NF as positive electrode and activated carbon as negative electrode. It exhibited a high energy density of 97.4 μWh cm −2 at a power density of 800.5 μW cm −2 , and retained 85.0% of initial capacity after 5000 cycles.