Fabrication and Electrochemical Properties of Sandwich-Type Nanoporous Nickel/Nickel Oxide Composite Electrodes

Abstract:

Nanoporous Nickel/Nickel Oxide (np-Ni/NiO) composite electrodes were fabricated with a “free dealloying - natural oxidation” method by dealloying a high ductile amorphous Ni₄₀Ti₆₀ precursor alloy in 0.25 M HF solution. The structure, morphologies and electrochemical properties of the composite electrodes were studied by XRD, SEM and Electrochemical measurements. The results indicate that the np-Ni/NiO composites exhibit a sandwich-type structure with "dealloyed layer︱amorphous alloy core︱dealloyed layer ". Due to the good connection between layers, the electrode material performs an excellent flexibility and structural integration. The thickness of the dealloyed layer and the content of NiO increase with extending the dealloying time. The volume capacitance of np-Ni/NiO by dealloying Ni₄₀Ti₆₀ ribbons in 0.25 M HF for 2 h can reach to 491.1 F/cm₃ at a discharge current density of 0.5 A/cm₃. After 6000 cycles, the volume capacitance remains at 472 F/cm₃, indicating an excellent cycle stability of np-Ni/NiO composite electrodes.

Key words:Ni-based amorphous alloy; dealloying; nanoporous nickel/nikel oxide; sandwich-type structure; specific capacitors