Does Alumina Coating Alter the Solid Permeable Interphase Dynamics in LiMn2O4 Cathodes?

It is well known that the Al2O3 coating of the LiMn2O4 cathodes leads to improvement of the performance of these electrodes. However, the effect of the coating on the fundamental processes occurring on the interface with the active material which results in the formation of the solid permeable interphase is yet to be investigated. These effects should be more pronounced in the first cycle when a dynamic interaction of the active material at high voltage with the electrolyte and binder leads to the formation of this passivation layer. Here, we present a detailed investigation of the solid permeable interphase formation in alumina-coated and uncoated LiMn2O4 electrodes using X-ray absorption spectroscopy and analysis on the electrodes at the predesigned charging/ discharging states. We demonstrate that the alumina coating leads to modification of the solid permeable layer and its dynamics. We also discuss the possible influences of interface modifications via coating on the battery performance.