Post-synthetic treatments on NixMnxCo1 − 2x(OH)2 for the preparation of lithium metal oxides

A series of hydroxides NixMnxCo(1−2x)(OH)2 for x = 0.00–0.50 were prepared. These hydroxides were used as the precursors in the synthesis of electrochemical active lithiated mixed metal oxides, LiNixMnxCo(1 − 2x)O2. The traditional co-precipitation method was used to synthesize the hydroxides and the effect of different post-synthetic treatments were tested. The solutions after co-precipitation of the hydroxides were heated under hydrothermal or microwave assisted hydrothermal conditions at 180 °C. All samples were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. We observed that the hydroxides undergo oxidation to an oxyhydroxide phase as the stoichiometry varies during their synthesis and with post-synthetic treatments. As the concentration of Ni and Mn increases in the sample, a mixture of both hydroxide and oxyhydroxide phases is obtained. SEM images demonstrate a sintering effect on the hydroxide particles after post-synthetic treatment, while XRD measurements on these samples show an increase in crystallinity and reduced turbostratic disorder. The oxides synthesized from these precursors demonstrate similar electrochemical performance with one another.

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► NixMnxCo(1−2x)(OH)2 were prepared and subjected to post-synthetic treatments. For the first time these treatments were applied within the synthetic solution.
► Extended treatments increased the presence of oxidized phase and particle size.
► Electrochemical active lithiated oxides were prepared from treated hydroxides. We discuss the impact of treatments on particle size and electrochemical properties.