In Situ Assessment of LiMn₂O₄ Degradation during Prolonged Exposure in Carbonate-Based Electrolytes

The degradations of thin-film LiMn₂O₄ electrodes during prolonged exposure to 1 M LiPF₆/EC-DMC at room temperature and 55°C, were assessed by in situ Raman spectroscopy. Our results demonstrate that different deterioration mechanisms of the spinel were found depending on the temperature. Exposure of a thin-film spinel LiMn ₂O₄ electrode to LiPF₆/EC-DMC electrolyte at room temperature and 55°C led to spontaneous formation of a thin insulating surface layer. This process is accompanied by the transformation of the LiMn₂O₄ electrode surface into λ-MnO₂ and Mn₂O₃ at room temperature and 55°C, respectively.