Study of Mn dissolution from LiMn2O4 spinel electrodes using in situ totalreflection X-ray fluorescence analysis and fluorescence XAFS technique

The dissolution process of Mn from LiMn2O4 cathode into an electrolyte solu tion accompanied on electrochemical cycling at various temperature was stud ied for the first time by in situ methods using a combination of total refl ection X-ray fluorescence (TXRF) analysis and a capillary technique, When t he in situ cell was cycled at 50 degreesC, the Mn concentrations measured o n the 5th, 10th and 15th cycles were determined to be 11, 56 and 393 ppm, r espectively The concentration of Mn in the cell was shown to be the highest at the center of both electrodes. It was also found that dissolution of Mn from the cathode material takes place during the charge rather than the di scharge process. Mn K-XANES (X-ray absorption near-edge structure) spectra of the electrolyte solution revealed that Mn exists as Mn2+. (C) 2001 Elsev ier Science B.V. All rights reserved.