Role of Electrochemical Precipitation Parameters in Developing Mixed-Phase Battery-Grade Nickel Hydroxide

There is a high demand for nickel hydroxide as an engineering material used in the positive electrode of nickel metal hydride (Ni-MH) rechargeable batteries. These batteries are extensively used in various small instruments, disposable batteries, and electric vehicles. The structure of nickel hydroxide significantly influences the discharge capacity and energy density, key properties of Ni-MH batteries, and this structure is primarily determined by the synthesis method used. In this study, nickel hydroxide was synthesized using an electrochemical precipitation method, with current density acting as a parameter to control the desired phase of the product, whether α-nickel hydroxide, β-nickel hydroxide, or a combination of both. At a current density of 50 A/m2, the synthesized nickel hydroxide demonstrated a smaller particle size and a superior discharge electrochemical property in comparison to that generated at 500 A/m2. The effect of agitation in catholyte was also investigated to examine the change in discharge property of the precipitated material. The product synthesized at 500 A/m2 from an agitated catholyte exhibited a tap density of 1.24 g/cc and an improved discharge capacity of 254 mAh per gram of Ni(OH)2.