Role of coprecipitation and calcination of precursors on phase homogeneity and electrochemical properties of battery active materials

Abstract

Coprecipitation has previously been demonstrated to produce diverse compositions of battery precursor particles, frequently under the assumption that the precipitation of transition metals from the solution results in advantages with regards to efficient homogeneous local mixing of transition metal cations within the solid particles. Such mixing is generally considered as an advantage relative to solid state reaction of solid powders with the equivalent starting stoichiometry; however, very few studies have attempted to quantitatively confirm the impact of this local mixing on the resulting final materials. The extent to which local mixing from coprecipitation facilitates the mass transport of transition metals during the calcination process, which would be expected to aid in producing well crystallized single-phase particles, is not clear. Herein, this study will systematically compare the phase purity and crystallinity of oxide powders comprised of a blend of transition metals that were produced from either physical mixture of single transition metal precursors or multicomponent precursors produced via coprecipitation from solution. These experiments provide quantitative support for the role that local mixing, achieved via precipitation, plays in forming high crystallinity final materials with the desired phase. LiMn1.5Ni0.5O4 was used as a model multicomponent target final material after calcination.