| 1. |
- Forestier, C., et al.
(författare)
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Comparative investigation of solid electrolyte interphases created by the electrolyte additives vinyl ethylene carbonate and dicyano ketene vinyl ethylene acetal
- 2017
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 345, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the replacement of the carbonyl oxygen in VEC additive by =C(CN)(2) in the analogous dicyano ketene vinyl ethylene acetal (DCKVEA) on the electrochemical reduction profile is significant. Yet, the additives were proven, through IR spectroscopy supported by DFT computations, by applying EELS techniques and performing synthesis of a reduction product, to reduce in a similar way. Interestingly, the reduction-induced capacities were found to be quite different and can be explained either by the different properties of the SEI, from lithium carbonate and its malononitrile homologue, or by the different abilities of the two additives to solvate Li+.
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| 2. |
- Forestier, C., et al.
(författare)
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Facile reduction of pseudo-carbonates: Promoting solid electrolyte interphases with dicyanoketene alkylene acetals in lithium-ion batteries
- 2016
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 303, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Dicyanoketene ethylene and propylene acetals, DCKEA and DCKPA respectively, have been investigated as electrolyte additives for Li-ion batteries. The purpose was to assess the changes in reduction behaviour and solid electrolyte interphase (SEI) passivation properties upon replacing the carbonyl group of ethylene carbonate (EC) and propylene carbonate (PC) solvents, respectively, by the slightly more electronegative and highly conjugated =C(CN)(2) group. The experimental reduction potentials and the IR spectroscopy characterisation efforts were further supported by density functional theory (DFT) computations. The two additives were found to, in relatively small amount (0.5 wt%), provide beneficial effects on the capacity retention of 8 mAh cells cycled at 20 and 45 degrees C. Moreover, the additives proved to enhance the thermal stability of the lithiated graphite/electrolyte interface, as deduced from DSC measurements.
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| 3. |
- Grugeon, S., et al.
(författare)
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Towards a better understanding of vinylene carbonate derived SEI-layers by synthesis of reduction compounds
- 2019
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 427, s. 77-84
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Tidskriftsartikel (refereegranskat)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.
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