Identifying the components of the solid-electrolyte interphase in Li-ion batteries

Luning Wang; Anjali Menakath; Fudong Han; Yi Wang; Peter Y Zavalij; Karen J Gaskell; Oleg Borodin; Dinu Iuga; Steven P Brown; Chunsheng Wang; Kang Xu; Bryan W Eichhorn

doi:10.1038/s41557-019-0304-z

Identifying the components of the solid-electrolyte interphase in Li-ion batteries

Nat Chem. 2019 Sep;11(9):789-796. doi: 10.1038/s41557-019-0304-z. Epub 2019 Aug 19.

Authors

Luning Wang¹, Anjali Menakath², Fudong Han³, Yi Wang¹, Peter Y Zavalij¹, Karen J Gaskell¹, Oleg Borodin⁴, Dinu Iuga², Steven P Brown², Chunsheng Wang^{5

6}, Kang Xu⁷, Bryan W Eichhorn⁸

Affiliations

¹ Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
² Department of Physics, University of Warwick, Coventry, UK.
³ Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.
⁴ Electrochemistry Branch, Power and Energy Division Sensor and Electron Devices Directorate, US Army Research Laboratory, Adelphi, MD, USA.
⁵ Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA. cswang@umd.edu.
⁶ Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA. cswang@umd.edu.
⁷ Electrochemistry Branch, Power and Energy Division Sensor and Electron Devices Directorate, US Army Research Laboratory, Adelphi, MD, USA. conrad.k.xu.civ@mail.mil.
⁸ Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA. eichhorn@umd.edu.

PMID: 31427766
DOI: 10.1038/s41557-019-0304-z

Abstract

The importance of the solid-electrolyte interphase (SEI) for reversible operation of Li-ion batteries has been well established, but the understanding of its chemistry remains incomplete. The current consensus on the identity of the major organic SEI component is that it consists of lithium ethylene di-carbonate (LEDC), which is thought to have high Li-ion conductivity, but low electronic conductivity (to protect the Li/C electrode). Here, we report on the synthesis and structural and spectroscopic characterizations of authentic LEDC and lithium ethylene mono-carbonate (LEMC). Direct comparisons of the SEI grown on graphite anodes suggest that LEMC, instead of LEDC, is likely to be the major SEI component. Single-crystal X-ray diffraction studies on LEMC and lithium methyl carbonate (LMC) reveal unusual layered structures and Li⁺ coordination environments. LEMC has Li⁺ conductivities of >1 × 10^-6 S cm^-1, while LEDC is almost an ionic insulator. The complex interconversions and equilibria of LMC, LEMC and LEDC in dimethyl sulfoxide solutions are also investigated.