High-Temperature Chemical Oxidation Pathways in Lithium-ion Batteries: Mechanistic insights into Ethylene Carbonate Decomposition

Higher states of charge have been shown to exacerbate the onset and severity of these events. This has been attributed to the release of lattice oxygen in cells containing Ni-rich layered oxide electrodes.

The degradation reactions on the electrode/electrolyte interface triggered by this oxygen remain insufficiently understood. In this study, we investigate high-temperature degradation pathways of ethylene carbonate (EC)-based electrolytes in contact with Ni-rich positive electrode active materials up to 130 ◦C. By combining in-situ high-temperature online electrochemical mass spectrometry with post-mortem analyses, we identify and validate key degradation intermediates and products.