Characteristics of stabilized spinel cathode powders obtained by in-situ coating method

TiO₂-coated LiMn₂O₄ cathode powders are prepared using an in situ spray pyrolysis process. The TiO₂-coated LiMn₂O₄ powders have spherical aggregated structures of nanometer-sized primary particles. The mean sizes of the primary and secondary TiO₂-coated LiMn₂O₄ powders are 55 and 880 nm, respectively. The transmission electron microscopy images of the LiMn ₂O₄ primary particles show a single-crystalline and well-faceted structure. The single-crystalline LiMn₂O₄ primary particles are uniformly coated with an amorphous TiO₂ layer. An immediate reaction of titanium tetraisopropoxide with oxygen forms a small flame at the exit of an alumina tube located in the center part of a quartz reactor. Sudden collisions between TiO₂ vapor and submicron-sized composite powders of the Li and Mn components occur to form the TiO ₂-coated cathode powders. The discharge capacities of the TiO ₂-coated LiMn₂O₄ cathode powders are 126 and 109 mAh g^-1 in the first and 170 cycles at a current density of 1 C. The capacity retentions of the pure and TiO₂-coated LiMn ₂O₄ powders are 69% and 86% of the initial capacity after 170 cycles.