China Nonferrous Metallurgy

This study systematically investigates the electrochemical behavior of Co²⁺ in a choline chloride-ethylene glycol system and its impact mechanism on the preparation of Ni-Co alloy. Analysis via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) revealed that increasing Co²⁺ concentration significantly enhances its redox reaction activity. The charge transfer resistance (Rct) decreases in the negative potential region, confirming that a high-concentration system facilitates electron transfer and promotes Co²⁺ reduction. Fitting LSV data with the Levich equation demonstrated a positive correlation between the diffusion coefficient (D) and Co²⁺ concentration. Characterization and analysis of the electrochemically co-deposited Ni-Co alloy showed that scanning electron microscopy and transmission electron microscopy (SEM/TEM) analyses indicated an increase in the nickel-to-cobalt ratio of the coating with rising Ni/Co concentration ratio in the electrolyte. X-ray diffraction (XRD) analysis confirmed that the Ni-Co alloy possesses a single-phase solid-solution structure, with Co atoms occupying Ni lattice sites in a substitutional manner without forming intermetallic compound phases.