Re-Deposition Of Aluminum Species After Dissolution To Improve Electrode Performances Of Lithium Manganese Oxide

In order to address the role of aluminum dopant in spinel-structured lithium manganese oxide (Li1.08Mn1.84Al0.08O3.96, Al-doped LMO) electrode, high-temperature (60 degrees C) charge/discharge cycling and storage experiments are carried out. The Al-doped LMO outperforms the un-doped counterpart with respect to capacity fading and Mn dissolution. However, the electrode polarization becomes substantial for the Al-doped LMO after the high-temperature storage. As the resistive component to be responsible for the electrode polarization, Al2O3 and Al(OH)(x)F3-x are identified on the Al-doped LMO surface from X-ray photoelectron spectroscopy study. It is very likely that the doped Al ions dissolve into the electrolyte during the high-temperature storage but re-deposit as a form of Al2O3 and Al(OH)(x)F3-x on the LMO surface. Due to a scavenging action of these Al species for hydrogen fluoride, Mn dissolution is suppressed to give an improved cycle and storage performance at elevated temperature. (C) 2014 The Electrochemical Society. All rights reserved.