Surface energies control the anisotropic growth of β -Ni(OH)$_2$ nanoparticles in stirred reactors

Nickel hydroxides are an important family of electrode materials in the field of batteries and electrochemical energy storage. Two polymorphs, -Ni(OH)$_2$ and -Ni(OH)$_2$ have been identified, with intermediate structures also reported. However, the synthesis of the -phase precipitants that are ideal for electrochemical applications is not trivial. The growth and morphology of the final products can widely vary with the pH. The electrochemical performance of the -phase is sensitive to its structure and morphology, which are also sensitive to the reaction conditions. In order to better understand the initial nucleation, growth and morphological evolution of the -phase, we present a combined experimental and theoretical study including a multiscale phase-field model for the evolution of the morphology of -Ni(OH)$_2$ . Surface indices and energies for the phase-field modeling were obtained from density functional calculations (DFT). The developed phase-field model can reproduce the growth of -Ni(OH)$_2$ phase in different conditions. The model shows that the basal planes of -Ni(OH)$_2$ can grow in high pH but at the same time its growth is limited by other high energy prismatic surfaces.