Reactions of singly-reduced ethylene carbonate in lithium battery electrolytes: A molecular dynamics simulation study using the ReaxFF

Dmitry Bedrov, Grant D. Smith, Adri Van Duin

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Abstract

We have conducted quantum chemistry calculations and gas- and solution-phase reactive molecular dynamics simulation studies of reactions involving the ethylene carbonate (EC) radical anion EC - using the reactive force field ReaxFF. Our studies reveal that the substantial barrier for transition from the closed (cyclic) form, denoted c-EC -, of the radical anion to the linear (open) form, denoted o-EC -, results in a relatively long lifetime of the c-EC - allowing this compound to react with other singly reduced alkyl carbonates. Using ReaxFF, we systematically investigate the fate of both c-EC - and o-EC - in the gas phase and EC solution. In the gas phase and EC solutions with a relatively low concentration of Li +/x-EC - (where x = o or c), radical termination reactions between radical pairs to form either dilithium butylene dicarbonate (CH 2CH 2OCO 2Li) 2 (by reacting two Li +/o-EC -) or ester-carbonate compound (by reacting Li +/o-EC - with Li +/c-EC -) are observed. At higher concentrations of Li +/x-EC - in solution, we observe the formation of diradicals which subsequently lead to formation of longer alkyl carbonates oligomers through reaction with other radicals or, in some cases, formation of (CH 2OCO 2Li) 2 through elimination of C 2H 4. We conclude that the local ionic concentration is important in determining the fate of x-EC - and that the reaction of c-EC - with o-EC - may compete with the formation of various alkyl carbonates from o-EC -/o-EC - reactions.

Original languageEnglish (US)
Pages (from-to)2978-2985
Number of pages8
JournalJournal of Physical Chemistry A
Volume116
Issue number11
DOIs
StatePublished - Mar 22 2012

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

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