Abstract:

Nickel-cobalt hydroxide is widely adopted as an electrode material in nickel-zinc batteries owing to its high theoretical specific capacity, economic benefits, and abundant availability. Leveraging a coprecipitation method, this study modulates the concentrations of various nitrate solutions with different nickel-cobalt ratios, enabling the one-step room-temperature synthesis of nickel-cobalt bimetallic hydroxides. Notably, the synthesized samples are intended for use as positive electrode materials in nickel-zinc batteries. Microstructural characterizations of the synthesized samples are performed using several techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. Furthermore, the electrochemical performance of the samples as electrode materials for nickel-zinc batteries is assessed using an electrochemical workstation. The results reveal that using a high-concentration NaOH solution as the electrolyte results in higher capacities for nickel-zinc batteries compared to other nickel-cobalt hydroxides prepared via coprecipitation techniques. Notably, the optimal capacity is achieved at a nickel-cobalt feed ratio of 4∶1. Specifically, the Ni₄Co₁-LDH sample demonstrates the best performance, reaching a capacity of 327.9 mAh/g at a current density of 0.5 A/g. Consequently, a nickel-zinc battery is assembled using the Ni₄Co₁-LDH sample as its positive electrode material and zinc foil as its negative electrode material, with a high-concentration NaOH solution for electrochemical testing. Results reveal that the battery demonstrates a capacity of 230.7 mAh/g at a current density of 0.5 A/g. Overall, the proposed approach offers advantages of rapid material synthesis and excellent performance, thus offering new insights for the performance optimization of nickel-zinc batteries.

Key words: co-precipitation method, nickel cobalt hydroxide, cathode material, nickel zinc battery