Identification of Diethyl 2,5-Dioxahexane Dicarboxylate and Polyethylene Carbonate as Decomposition Products of Ethylene Carbonate Based Electrolytes by Fourier Transform Infrared Spectroscopy
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AbstractThe formation of passive films on electrodes due to electrolyte decomposition significantly affects the reversibility of Li-ion batteries (LIBs); however, understanding of the electrolyte decomposition process is still lacking. The decomposition products of ethylene carbonate (EC)-based electrolytes on Sn and Ni electrodes are investigated in this study by Fourier transform infrared (FTIR) spectroscopy. The reference compounds, diethyl 2,5-dioxahexane dicarboxylate (DEDOHC) and polyethylene carbonate (poly-EC), were synthesized, and their chemical structures were characterized by FTIR spectroscopy and nuclear magnetic resonance (NMR). Assignment of the vibration frequencies of these compounds was assisted by quantum chemical (Hartree-Fock) calculations. The effect of Li-ion solvation on the FTIR spectra was studied by introducing the synthesized reference compounds into the electrolyte. EC decomposition products formed on Sn and Ni electrodes were identified as DEDOHC and poly-EC by matching the features of surface species formed on the electrodes with reference spectra. The results of this study demonstrate the importance of accounting for the solvation effect in FTIR analysis of the decomposition products forming on LIB electrodes. © 2014 American Chemical Society.
CitationShi F, Zhao H, Liu G, Ross PN, Somorjai GA, et al. (2014) Identification of Diethyl 2,5-Dioxahexane Dicarboxylate and Polyethylene Carbonate as Decomposition Products of Ethylene Carbonate Based Electrolytes by Fourier Transform Infrared Spectroscopy. The Journal of Physical Chemistry C 118: 14732–14738. Available: http://dx.doi.org/10.1021/jp500558x.
SponsorsThis work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Freedom CAR and Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02 O5CH1123 and the UCB-KAUST Academic Excellence Alliance (AEA) Program. The IR instrumentation was purchased with funding from the Director, Office of Basic Energy Sciences, Materials Science and Engineering Division of the U.S. Department of Energy.
PublisherAmerican Chemical Society (ACS)