Cathode performance of LiMnPO4/C nanocomposites prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment

LiMnPO4/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment in the range of spray pyrolysis temperature from 200 to 500 degrees C. The ordered LiMnPO4 olivine structure without any impurity phase could be identified by X-ray diffraction analysis for all samples. It could be also confirmed from scanning electron microscopy and transmission electron microscopy observations that the final samples were the LiMnPO4/C nanocomposites with approximately 100 nm in primary particles size. The LiMnPO4/C nanocomposite samples were used as cathode active materials for lithium batteries, and the electrochemical tests were carried out for the cell Li/1 M LiPF6 in EC:DMC = 1:1/LiMnPO4/C at various charge/discharge rates in three charge modes. As a result, the final sample which was synthesized at 300 degrees C by spray pyrolysis showed the best electrochemical performance due to the largest specific surface area, the smallest primary particle size and a well distribution of carbon. At galvanostatic charge/discharge rates of 0.05 C, the cell delivered first discharge capacities of 123 and 165 mAh g(-1) in correspondence to charge cutoff voltages of 4.4 and 5.0 V, respectively. Furthermore, in a constant current-constant voltage charge mode at 4.4 V, the cells also exhibited initial discharge capacities of 147 mAh g(-1) at 0.05 C, 145 mAh g(-1) at 0.1 C, 123 mAh g(-1) at 1 C and 65 mAh g(-1) at 10C. Moreover, the cells showed fair good cycleability over 100 cycles. (C) 2010 Elsevier B.V. All rights reserved.