LiMn2O4/LiNi0.5Mn1.5O4 composite with improved electrochemical property

LiMn2O4/LiNi0.5Mn1.5O4 composite with LiMn2O4 substrate and LiNi0.5Mn1.5O4 surface layer is proposed and prepared through sol-gel method. The resulting samples have been characterized by XRD and SEM measurements, in terms of which the impurity-free phase, uniform particle morphology have been proved. Charge-discharge test, XPS measurement combining with TEM observation confirm the existence of LiNi0.5Mn1.5O4 surface layer. Comparing with the bare LiMn2O4, the LiNi0.5Mn1.5O4-coated LiMn2O4 phase presents significantly improved cycling stability, especially at 60 degrees C. Additionally, the rate capability and thermal safety of LiMn2O4 are greatly enhanced after being coated by LiNi0.5Mn1.5O4. ICP-AES measurement, structural analysis, and impedance experiment indicate that the improved electrochemical property of LiNi0.5Mn1.5O4-coated LiMn2O4 should be attributed to the alleviated dissolution loss of manganese, strengthened structural stability, and improved SEI property. (C) 2013 Elsevier Ltd. All rights reserved.