Hydrothermal Synthesis of Layered Li[Ni0.5Mn0.5]O2 as Lithium Intercalation Material

In attempt to synthesize layered Li[Ni0.5Mn0.5]O2, a hydrothermal method has been employed. First, the spherical powder precursor, [Ni0.5Mn0.5](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[Ni0.5Mn0.5]O2 having (alpha)-NaFeO2 structure (space group:R3m ). The asprepared 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.