Application of the Box–Behnken design in the response surface methodology for the precipitation of Ni/Ni oxalate composite anodes

In this work, first, using the Box–Behnken method, the temperature, oxalic acid/nickel mole ratio, and stirring duration are optimized to maximize the precipitation efficiency of nickel oxalate. Then, ANOVA is used to study the statistically significant parameters and their interactions. At 42.5 °C, with a 1.25 oxalic acid/nickel mole ratio and a 135 min stirring duration, 99.94% precipitation efficiency is achieved. A good agreement (R ² = 0.9535) between the predicted and experimental values is reported. Then, this obtained nickel oxalate hydrate is heat-treated at 290 °C for 3 h in a vacuum and turned into a composite made of anhydride oxalate and metallic nickel. The possible use of this composite as an anode material is first investigated: it delivers a capacity of 552.24 mAh g⁻¹ after 100 cycles under a load of 100 mA g⁻¹. Cyclic voltammetry is utilized to probe its lithiation mechanism. The structural and morphological properties of the composite are cited as a reason for its good cycling performance. Graphical abstract: [Figure not available: see fulltext.].