A novel coprecipitation method towards the synthesis of NixMnxCo(1–2x)(OH)2 for the preparation of lithium metal oxides

Abstract

A series of mixed metal hydroxide (Ni x Mn x Co(1–2x)(OH)2) precursors for the preparation of lithiated mixed metal oxides (LiNi x Mn x Co(1–2x)O2) were prepared using a novel coprecipitation approach based on the thermal decomposition of urea. Three different methods were used to achieve the temperature required to decompose urea and subsequently precipitate the hydroxides. The first two methods consisted of either a hydrothermal or microwave-assisted hydrothermal synthesis at 180 °C and elevated pressures. The final method was an aqueous reflux at 100 °C. A complete series (x = 0.00–0.50) was prepared for each method and fully characterized before and after converting the materials to lithiated metal oxides (LiNi x Mn x Co(1–2x)O2). We observed the formation of a complex structure after the coprecipitation of the hydroxides. Scanning electron micrographs images demonstrate that the morphology and particle size of the hydroxide particles varied significantly from x = 0.00–0.50 under hydrothermal synthesis conditions. There is also a significant change in particle morphology as the urea decomposition method is varied. The X-ray diffraction profiles of the oxides synthesized from these hydroxide precursors all demonstrated phase pure oxides that provided good electrochemical performance.