Hydrothermal synthesis of layered Li[Ni{sub}(1/3)Co{sub}(1/3)Mn{sub}(1/3)]O{sub}2 as positive electrode material for lithium secondary battery

摘要

In attempts to prepare layered Li[Ni{sub}(1/3)Co{sub}(1/3)Mn{sub}(1/3)]O{sub}2, hydrothermal method was employed. The hydrothermal precursor, [Ni{sub}(1/3)Co{sub}(1/3)Mn{sub}(1/3)](OH){sub}2, was synthesized via a coprecipitation route. The sphere-shaped powder precursor was hydrothermally reacted with LiOH aqueous solution at 170℃ for 4 days in autoclave. From X-ray diffraction and scanning electron microscopic studies, it was found that the as-hydrothermally prepared powders were crystallized to layered α-NaFeO{sub}2 structure and the particles had spherical shape. The as-prepared Li[Ni{sub}(1/3)Co{sub}(1/3)Mn{sub}(1/3)]O{sub}2 delivered an initial discharge of about 110 mAhg{sup}(-1) due to lower crystallinity. Heat treatment of the hydrothermal product at 800 ℃ was significantly effective to improve the structural integrity, which consequently affected the increase in the discharge capacity to 1.57 (4.3 V cut-off) and 182mAhg{sup}(-1) (4.6 V cut-off) at 25 ℃ with good reversibility.