Lithium ethylene dicarbonate identified as the primary product of chemical and electrochemical reduction of EC in 1.2 M LiPF6/EC:EMC electrolyte

Guorong V Zhuang; Kang Xu; Hui Yang; T Richard Jow; Philip N Ross Jr

doi:10.1021/jp052474w

Lithium ethylene dicarbonate identified as the primary product of chemical and electrochemical reduction of EC in 1.2 M LiPF6/EC:EMC electrolyte

J Phys Chem B. 2005 Sep 22;109(37):17567-73. doi: 10.1021/jp052474w.

Authors

Guorong V Zhuang¹, Kang Xu, Hui Yang, T Richard Jow, Philip N Ross Jr

Affiliation

¹ Materials Sciences and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA. GVZhuang@lbl.gov

PMID: 16853247
DOI: 10.1021/jp052474w

Abstract

Lithium ethylene dicarbonate ((CH2OCO2Li)2) was chemically synthesized and its Fourier transform infrared (FTIR) spectrum was obtained and compared with that of surface films formed on Ni after cyclic voltammetry (CV) in 1.2 M lithium hexafluorophosphate (LiPF6)/ethylene carbonate (EC):ethyl methyl carbonate (EMC) (3:7, w/w) electrolyte and on metallic lithium cleaved in-situ in the same electrolyte. By comparison of IR experimental spectra with that of the synthesized compound, we established that the title compound is the predominant surface species in both instances. Detailed analysis of the IR spectrum utilizing quantum chemical (Hartree-Fock) calculations indicates that intermolecular association through O...Li...O interactions is very important in this compound. It is likely that the title compound in the passivation layer has a highly associated structure, but the exact intermolecular conformation could not be established on the basis of analysis of the IR spectrum.