Effect of Surface Treatment with Titanate Coupling Agent on Structure and Performance of LiMn2O4
TiO2 was coated on the surface of LiMn2O4 by thermal decomposition of titanate coupling agent,and the effects of coating treatment on the structure and electrochemical performance of LiMn2O4,as well as material structure in the cycling were all explored.The results show that TiO2 can be uniformly coated on the surface of the LiMn2O4 by thermal decomposition of titanate coupling agent at 550 ℃.Surface coating does not change the crystal structure of LiMn2O4,but obviously improves its electrochemical performance,especially high temperature rate performance and cycle performance.At 55 ℃,LiMn2O4 with TiO2 coating delivers a specific capacity of 75.34 mAh/g at 5C,which is higher than that without coating(43.05 mAh/g).After 150 cycles,the capacity retention rate of the material with TiO2 coating and without coating is 77.27％and 62.85％,respectively.The improvement of electrochemical performance is attributed to reduction of Mn dissolution in the cathode material by TiO2 coating,which thus inhibits the change of crystal structure during cycling process,reduces the electrode polarization and charge transfer impedance,as well as improves the charge-discharge reversibility of the material and the Li+diffusion.
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