Electrochemical and spectroscopic characterization of an alumina-coated LiMn2O4 cathode with enhanced interfacial stability

Pristine LiMn2O4, synthetized by solid-state route, is coated by an Al2O3 layer through co-precipitation method, in order to enhance the electrochemical performances and stability of the cathode, especially at high temperatures. Structural analysis by X-ray diffraction and morphological characterization by scanning and transmission electron spectroscopy reveal phase pure and crystalized nanomaterial forming clusters. The cycling performances of pristine and modified materials are investigated by galvanostatic cycles at several charge/discharge rates. A detailed analysis of the interfacial properties, and of their impact toward cycling behavior, is carried out by combining galvanostatic cycles at 1C and electrochemical impedance spectroscopy at T = 25 °C and T = 50 °C. The results show that the electrode/electrolyte interface of Al2O3-modified LiMn2O4 is stabilized by suppressing Mn dissolution, resulting in improved cycleability, especially at high temperatures. These results are corroborated by X-ray photoelectron spectroscopy studies, which confirm the suppression of Mn dissolution for the Al2O3–coated material.