One of the critical challenges for lithium manganese oxide spinel-based batteries is the severe capacity fade due to Mn dissolution from the spinel, especially at high temperature.In this talk, we will start from a model system with an inert Cu electrode and fluorine-free electrolyte, which eliminates the complexity of Li insertion in the active materials as well as the presence of HF. The goal is to elucidate the fundamental steps of how the presence of Mn in the electrolyte impacts the formation of SEI. How Mn dissolution influences the electrode surfaces and how the changes in surface chemistry harm battery long term viability will be discussed. Mn was found throughout the SEI, but not uniformly distributed. Also, the presence of Mn substantially increased the SEI formation and changed its composition and impedance. We take advantage of the fact that degradation films on both electrodes can be dissolved, and we remove the SEI contaminated with Mn by soaking the degraded electrodes in solvents. The relationships between these film properties and their effects on battery performance are described. We show a significant reduction in impedance from dissolving away these films.

Mn dissolution induced surface related battery degradation and method to mitigate by simple surface treatment

246th National Meeting (2013)

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