Enhanced electrochemical performance of high-density Al-substituted α-nickel hydroxide by a novel anion exchange method using NaCl solution

High-density Al-substituted α-nickel hydroxide with interlayer NO3− for alkaline nickel-based rechargeable batteries has been synthesized using a polyacrylamide (PAM) assisted two-step drying method. In order to improve its electrochemical performance, Al-substituted α-Ni(OH)2 with interlayer NO3− is modified by a simple anion exchange method using NaCl solution. The physical and electrochemical properties of the synthesized material are characterized by means of X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and a charge–discharge test. Compared with NO3− intercalated α-Ni(OH)2 precursor, the resulting Cl− intercalated α-Ni(OH)2 samples possess more excellent electrochemical activities, including higher proton diffuse coefficient, lower electrochemical impedance, higher specific capacity, and better cyclic stability. Especially, it is also found that the introduction of Cl− can greatly accelerate the activation process of α-Ni(OH)2 electrodes.