Hydrolysis of Ethylene Carbonate with Water and Hydroxide under Battery Operating Conditions. Issue 7 (14th April 2016)

• Record Type: Journal Article
• Authors: Metzger, Michael; Strehle, Benjamin; Solchenbach, Sophie; Gasteiger, Hubert A.
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 7(2016)
• Page Start: A1219
• Page End: A1225
• Publication Date: 2016-04-14
• Subjects: Ethylene Carboante -- Gassing -- Hydrolysis -- Hydroxide ions -- Lithium-ion batteries -- On-line Electrochemical Mass Spectrometry; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0411607jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : This study deals with the decomposition of ethylene carbonate (EC) by H2 O in the absence and presence of catalytically active hydroxide ions (OH − ) at reaction conditions close to lithium-ion battery operation. We use On-line Electrochemical Mass Spectrometry (OEMS) to quantify the CO2 evolved by these reactions, referred to as H2 O-driven and OH − -driven EC hydrolysis. By examining both reactions at various temperatures (10 – 80°C) and water concentrations (<20 ppm or 200, 1000, and 5000 ppm H2 O) with or without catalytically active OH − ions in EC with 1.5 M LiClO4, we determine an Arrhenius relationship between the CO2 evolution rate and the cell temperature. While the apparent activation energy for the base electrolyte (<20 ppm H2 O) is very large (app. Ea ≈153 kJ/mol), substantially lower values are obtained in the presence of H2 O (app. Ea ≈99 ± 3 kJ/mol), which are even further decreased in the presence of catalytically active OH − (app. Ea ≈43 ± 5 kJ/mol). Our data show that OH − -driven EC hydrolysis is relevant already at room temperature, whereas H2 O-driven EC hydrolysis (i.e., without catalytically active OH − ) is only relevant at elevated temperature (≥40°C), as is the case for the base electrolyte. Thus, catalytic quantities of OH −, e.g., from hydroxide contaminants on the surface of transition metal oxide based active materials, would be expected to lead to considerable CO2 gassing in lithium-ion cells.