When considering the design of new high-energy storage systems, new materials, processes, or chemistries are introduced that are inherently more unstable than conventional Li-ion battery materials, resulting in limited battery cycle life and safety. One such example, high voltage (&gt;4.4 V vs Li/Li+) operation of Ni-rich Li[Ni, Mn, Co]O2 Li+ insertion electrodes (Ni-rich NMC), will be discussed in this presentation. Previous observations of high-voltage instabilities include NMC surface reconstruction, transition metal dissolution, electrolyte decomposition, and formation of solid surface species. However, the picture of these processes is still incomplete, with the dependence on electrolyte and NMC composition not yet fully understood. I will present results in which isotopic labeling of 18O in Ni-rich NMCs is combined with quantitative gas evolution analysis to identify key contributions to these high voltage instabilities, including instabilities related to solid-state anionic oxygen redox and the surprising impact of residual solid lithium carbonate on electrolyte and electrode degradation. This presentation will emphasize the need to accurately quantify these minor parasitic side reactions to fully understand their large influence on battery performance.

Quantifying outgassing, surface oxygen depletion, and solid carbonate evolution in Li(Ni, Co, Mn)O2 Li-ion cathodes

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.