Surface modification of LiMn2O4 thin films at elevated temperature

In order to improve the cycle stability of spinel LiMn2O4 electrode at elevated temperature, the LiCoO2-coated and Co-doped LiMn2O4 film were prepared by an electrostatic spray deposition (ESD) technique. LiCoO2-coated LiMn2O4 film shows excellent cycling stability at 55 °C compared to pristine and Co-doped LiMn2O4 films. The samples were studied by X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The excellent performance of LiCoO2-coated LiMn2O4 film can be explained by suppression of Mn dissolution. On the other hand, the LiCoO2-layer on the LiMn2O4 surface allows a homogenous Li+ insertion/extraction during electrochemical cycles and improves its structure stability.