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Published online by Cambridge University Press: 20 July 2012
Olivine lithium manganese phosphate, LiMnPO4 is a promising cathode material for high energy and safe lithium ion batteries. However, LiMnPO4 possesses excessively poor electrochemical activity, compared to conventional cathode materials. To enhance the electrochemical activity, we have synthesized LiMnPO4/multi-walled carbon nanotube (MWCNT) composites by employing an in-situ sol-gel method. The LiMnPO4/MWCNT composites were investigated by utilizing X-ray diffraction, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and galvanostatic charge-discharge cycling. The LiMnPO4 showed a particle size of ca. 50 nm and capacity of 102 mAh/g at 0.1 C without C.V. charging mode. This study demonstrated that the electrochemical activity of LiMnPO4 was significantly affected by not only pH and the amount of a chelating agent but also unreacted Mn2+. This is the first report analyzing the existence and effects of unreacted Mn2+ in LiMnPO4 synthesized by a sol-gel method.