Effect of boric acid on the properties of Li2MnO3•LiNi0.5Mn0.5O2 composite cathode powders prepared by large-scale spray pyrolysis with droplet classifier

Spherically shaped 0.3Li(2)MnO(3)center dot 0.7LiNi(0.5)Mn(0.5)O(2) composite cathode powders with filled morphology and narrow size distribution are prepared by large-scale spray pyrolysis. A droplet classification reduces the standard deviation of the size distribution of the composite cathode powders. Addition of boric acid improves the morphological properties of the product powders by forming a lithium borate glass material with low melting temperature. The optimum amount of boric acid dissolved in the spray solution is 0.8 wt% of the composite powders. The powders prepared from the spray solution with 0.8 wt% boric acid have a mixed layered crystal structure comprising Li2MnO3 and LiNi0.5Mn0.5O2 phases, thus forming a composite compound. The initial charge and discharge capacities of the composite cathode powders prepared from the 0.8 wt% boric acid spray solution are 297 and 217 mAh g(-1) respectively. The discharge capacity of the powders decreases from 217 to 196 mAh g(-1) by the 30th cycle, in which the capacity retention is 90%. (C) 2012 Elsevier Ltd. All rights reserved,