Early Stages of Battery Electrolytes Degradation: Theory and Experiment
Alia Tadjer, Georgi Vassilev, Rositsa Kukeva, Hristo Rasheev, Ivo Lozanov, Mariya Kalapsazova, Radostina Stoyanova
Abstract: The electrochemical stability window (ESW) is an important characteristic of electrolytes in general and particularly of battery electrolytes. It is believed that within this voltage window no redox processes involving the electrolyte components occur. However, the literature data available for the ESWs of standard electrolytes are very ambiguous as the measurements depend on a number of factors and there is no established protocol for the experimental assessment of this property.
Recently, tailored EPR experiments registered the presence of radicals in lithium- and sodium-ion batteries electrolytes even in the voltage ranges considered to be their respective ESWs [1]. Apparently, these radicals are products of the partial degradation of the solvents but the salts employed also play a role, because dissimilar radicals were identified upon the utilization of different salts. Knowledge about these redox reactions is very important for the battery safety and durability.
Combining experimental techniques (EPR, LSV, CV) and molecular modelling (DFT), this study aims at clarifying the type and mechanism of the redox processes taking place within the ESWs of the most typical electrolytes used in lithium- and sodium-ion batteries.
[1] R. Kukeva, M. Kalapsazova, H. Rasheev, G. Vassilev, A. Tadjer and R. Stoyanova. “In Situ Electron Paramagnetic Resonance Monitoring of Predegradation Radical Generation in a Lithium Electrolyte”. J. Phys. Chem. Lett. 14 (2023) 9633-9639, DOI:10.1021/acs.jpclett.3c02374.
The study is carried out with the financial support of the Bulgarian National Science Fund, contract CARiM (NSP VIHREN, ΚΠ-06-DB-6).
The authors from CARiM’s Research Team are bolded.
VIHREN-CARiM 2019 