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Decomposition of Carbonate‐Based Electrolytes: Differences and Peculiarities for Liquids vs. Polymers Observed Using Operando Gas Analysis
Author(s) -
Sångeland Christofer,
Sun Bing,
Brandell Daniel,
Berg Erik J.,
Mindemark Jonas
Publication year - 2021
Publication title -
batteries and supercaps
Language(s) - English
Resource type - Journals
ISSN - 2566-6223
DOI - 10.1002/batt.202000307
Subject(s) - ethylene carbonate , electrolyte , chemistry , carbonate , electrochemistry , dimethyl carbonate , solvent , inorganic chemistry , polymer , cyclic voltammetry , decomposition , chemical decomposition , electrode , organic chemistry , methanol
Direct tracking of solid polymer electrolyte (SPE) decomposition in comparison to a liquid analogue was accomplished by monitoring the evolution of volatile species using online electrochemical mass spectrometry (OEMS). Reduction of a poly(trimethylene carbonate)‐based SPE was dominated by CO 2 formation. Detection of CO 2 and an absence of CO confirms a preferred reduction degradation pathway involving C−O bond cleavage at the carbonyl carbon, in correlation with earlier suggestions. In contrast, the alkyl carbonate‐based liquid electrolyte exhibited extensive ethylene formation. Trace quantities of H 2 evolution ascribed to water impurities were also observed in both systems. During oxidation, the SPE and liquid electrolyte exhibited CO 2 , CO and SO 2 evolution synonymous with electrolyte solvent and salt degradation, albeit at different potentials. Overall, gas evolution rates and redox currents were lower in the SPE system. OEMS revealed significant gas formation independent of current response, as such highlighting the limitations of the voltammetry technique commonly used today to assess electrochemical stability.