Gas evolution from cathode materials: A pathway to solvent decomposition concomitant to SEI formation

• Published in: Journal of power sources 2013-10, Vol.239 (1), p.341-346
• Main Authors: Browning, Katie L., Baggetto, Loïc, Unocic, Raymond R., Dudney, Nancy J., Veith, Gabriel M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Battery safety; Coulombic losses; Electrical engineering. Electrical power engineering; Electrolyte decomposition; Exact sciences and technology; Gas evolution; Li-ion battery; Li-ion safety; Materials
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.03.118

This work reports a method to explore the catalytic reactivity of electrode surfaces toward the decomposition of carbonate solvents [ethylene carbonate (EC), dimethyl carbonate (DMC), and EC/DMC]. We show that the decomposition of a 1:1 wt% EC/DMC mixture is accelerated over certain commercially available LiCoO2 materials resulting in the formation of CO2 while over pure EC or DMC the reaction is much slower or negligible. The solubility of the produced CO2 in carbonate solvents is high (0.025 g mL−1) which masks the effect of electrolyte decomposition during storage or use. The origin of this decomposition is not clear but it is expected to be present on other cathode materials and may affect the analysis of SEI products as well as the safety of Li-ion batteries. •Surface chemistry of LiCoO2 will influence catalytic decomposition of electrolyte molecules.•CO2 solubility affected by solvent composition with solubilities up to 0.02 g CO2 mL−1.•Alternative to electrochemical SEI formation that may mediate cell lifetime.