Degradation mechanisms of the ethylene carbonate/diethyl carbonate mixture studied by radiolysis

Furong Wang (1) , Fanny Varenne (2) , Daniel Ortiz (2) , Valentin Pinzio (2) , Mehran Mostafavi (1) , Sophie Le Caer (2)

1 LCPO - Laboratoire de Chimie Physique D'Orsay
2 LIONS - Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire

The reactivity of ethylene carbonate (EC) and of the ethylene carbonate/diethyl carbonate (DEC) mixture is studied under ionizing radiation in order to mimic aging phenomena occurring in lithium-ion batteries. Picosecond pulse radiolysis experiments show that the attachment of the electron on EC molecule is ultrafast (k(e-EC + EC) = 1.3 10 9 L mol-1 s-1 at 46°C). In the case of the 50/50 EC/DEC mixture, just after the electron pulse, the electron is solvated by a mixture of EC and DEC molecules, but its fast decay is attributed to the electron attachment on the EC molecule exclusively. Stable products detected after steady-state irradiation include mainly H2, CH4, CO and CO2. The evolution of the radiolytic yields with the EC fraction shows that H2 and CH4 do not exhibit a linear behavior, whereas CO and CO2 obey it. Indeed, H2 and CH4 mainly arise from the excited state of DEC, whose formation is significantly affected by the evolution of the dielectric constant of the mixture and by the electron attachment on EC. CO formation is mainly due to the reactivity of the EC molecule that is not affected in the mixture as proven by pulse radiolysis experiments.

Domaines: Matériaux

Furong Wang, Fanny Varenne, Daniel Ortiz, Valentin Pinzio, Mehran Mostafavi, et al.. Degradation mechanisms of the ethylene carbonate/diethyl carbonate mixture studied by radiolysis. ChemPhysChem, 2017, 18, pp.2799-2806. ⟨10.1002/cphc.201700320⟩. ⟨cea-01513523⟩