Hydrothermal synthesis of layered Li[Ni_0.5Mn_0.5] O₂ as lithium intercalation material

In attempt to synthesize layered Li[Ni_0.5Mn_0.5]O ₂, a hydrothermal method has been employed. First, the spherical powder precursor, [Ni_0.5Mn_0.5](OH)₂, was prepared via a coprecipitation. Then, the precursor was hydrothermally reacted with an excess amount of LiOH aqueous solution at 170°C for 4 days. From X-ray diffraction investigation, it was found that the hydrothermally prepared powders showed the layered Li[Ni_0.5Mn_0.5]O₂ having α-NaFeO₂ structure (space group: R3m). The as-prepared powders delivered the initial discharge of about 104 mAh g^-1. Further calcination of the hydrothermally prepared powders at 800°C resulted in the well-ordered layered structure, indicating increase in the crystallinity. Subsequently, the resulting discharge capacity was also improved, 142 mAh g ^-1 by applying a current density of 20 mA g^-1 (1/8C) and the capacity retention was relatively good during cycling.