Surface energies control the anisotropic growth of [formula omitted]-Ni(OH)2 nanoparticles in stirred reactors

Abstract

Nickel hydroxides are an important family of electrode materials in the field of batteries and electrochemical energy storage. Two polymorphs, α-Ni(OH)2 and β-Ni(OH)2 have been identified, with intermediate structures also reported. However, the synthesis of the β-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 β-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 β-phase, we present a combined experimental and theoretical study including a multiscale phase-field model for the evolution of the morphology of β-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 β-Ni(OH)2 phase in different conditions. The model shows that the basal planes of β-Ni(OH)2 can grow in high pH but at the same time its growth is limited by other high energy prismatic surfaces.