1. Towards a better understanding of vinylene carbonate derived SEI-layers by synthesis of reduction compounds.
- Author
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Grugeon, Sylvie, Jankowski, Piotr, Cailleu, Dominique, Forestier, Coralie, Sannier, Lucas, Armand, Michel, Johansson, Patrik, and Laruelle, Stephane
- Subjects
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CHEMICAL reduction , *CARBONATES , *SUPERIONIC conductors , *BALL mills , *REDUCING agents - Abstract
Here two chemical reduction pathways to synthesize the vinylene carbonate (VC) and poly(VC) reduction products are investigated, with the precise aim of further deciphering the lithium-ion battery solid electrolyte interphase (SEI) layer composition and the associated reduction mechanisms. The liquid synthesis pathway offers the opportunity of varying the concentration of Li-4,4′-Di- tert -butylbiphenyl reducing agent, whereas the dry synthesis pathway by ball milling allows to solve issues related to solvent-induced side reactions and washing procedure. As a result, the two syntheses do not unveil the same reduction mechanisms, favouring either carboxylate or carbonate salts as the major end product. The latter pathway is very efficient in terms of providing SEI-layers products resulting in well-defined IR spectra and comparisons with simulated spectra enable us to obtain IR fingerprints of the Li di-vinylene di-carbonate (LDVD) compound. Taken together the synthesis procedures provide information on conditions favouring radical polymerization and further poly(VC) reduction into Li 2 CO 3 and polyacetylene. Overall, this chemical simulation of SEI-layers formation assists in a proper characterization of the SEI-layers created on graphite surfaces by their IR spectra showing that Li 2 CO 3 , LDVD and poly(VC) are all present in different proportions dependent on the VC content in the electrolyte. • Li 2 CO 3, Li divinylene dicarbonate and poly(VC) are all VC-derived SEI-layer compounds. • Poly(VC) can be reduced into Li 2 CO 3 and polyacetylene. • Dry ball milling with Li is helpful to synthesize SEI reduction compounds. • Radical polymerization processes prevail in presence of small amount of VC radicals. • EC also participates to the SEI formation in presence of electrolyte with 2 wt% VC. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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