High-capacity charge storage electrodes based on nickel oxide and nickel–cobalt double hydroxide nanocomposites on 3D nickel foam prepared by sparking and electrodeposition

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Abstract In the present work, nickel oxide (NiO) and nickel-cobalt double hydroxide (NiCo-DH) nanocomposites on Ni foams were synthesized for the first time and systemically optimized for charge storage applications. NiO nanoparticles were sparked on Ni foams followed by the electrodeposition of NiCo-DH with various times ranging from 50 to 400 s. Structural characterization results by electron microscopy, Raman spectroscopy and X-ray spectroscopy revealed that 5–10 nm sparked NiO nanoparticles acted as the nucleation seeds for the formation of smaller NiCo-DH nanostructures resulting in an increase of surface area at a moderate electrodeposition times of 100 s and induced metallic Ni and Co species on the composite layer. From electrochemical measurements, the optimal electrodeposition time of 100 s provided a moderate mass loading of 0.6 mg cm−2 and a high specific capacity of 938 C g−1 (1876 F g−1) @ 1 A g−1 with a good rate capability of 69% (647.5 C g−1) @ 20 A g−1. Additionally, a decent capacity retention of 97% was attained after 1000 cycles @ 4 A g−1. The results could be attributed to high surface capacity of NiO + NiCo-DH nanocomposite structures and high electrical conductivity with a low effective series resistance of 0.39 Ω.