Li-Ni-Mn-O cathode powders with various ratios of nickel and manganese components were prepared by ultrasonic spray pyrolysis from polymeric precursor solutions. The precursor powders obtained from the polymeric precursor solutions containing citric acid and ethylene glycol were several micrometre in size, had a spherical shape and hollow morphology irrespective of the ratios of nickel and manganese components. However, the morphology of the post-treated Li-Ni-Mn-O cathode powders were affected by the ratios of nickel and manganese components. The LiMn1.5Ni0.5O4 and LiNi0.5Mn0.5O2 cathode powders were several micrometre in size, had a hollow and spherical morphology. However, the LiMn2O4 and LiNi0.7Mn0.25O2 cathode powders had a fine size and regular morphology. The mean sizes of the LiMn2O4 and LiNi0.75Mn0.25O2 cathode powders were 1.2 and 0.26 pm, respectively. The initial discharge capacities of the prepared Li-Ni-Mn-O cathode powders were changed from 120 to 206 mAhg(-1) according to the ratios of nickel and manganese components.

Keywords: spray pyrolysis; cathode material; lithium secondary batteries