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 LiMn2O4 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 TiO2-coated cathode powders. The discharge capacities of the TiO2-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 LiMn2O4 powders are 69% and 86% of the initial capacity after 170 cycles. (C) 2013 Elsevier B.V. All rights reserved.