Effect of Vinylene Carbonate Additive in Li-Ion Batteries: Comparison of LiCoO2∕C, LiFePO4∕C, and LiCoO2∕Li4Ti5O12 Systems
Résumé
Vinylene Carbonate (VC) is a commonly used electrolyte additive in Li-ion batteries, because of its beneficial role on the formation of the solid electrolyte interphase (SEI). It was shown to contribute to surface film formation on both electrodes of LiCoO 2 /C cells via its radical polymerization mechanism. In this paper, we carried out a comparative study of the role of VC on electrode/electrolyte interfaces in LiCoO 2 /C, LiFePO 4 /C and LiCoO 2 /Li 4 Ti 5 O 12 systems, in which the potential and the chemical nature of each electrode are changed. Coincells were charged at different potentials using a LiPF 6 /EC:DEC:DMC liquid electrolyte with or without VC, and the electrodes were analyzed by X-ray Photoelectron Spectroscopy (XPS). We showed there is no interaction between the negative and the positive electrode in the VC polymerization mechanisms-for example by exchange of chemical species from one electrode to the other one-during the first charge. Separate mechanisms occur, although the same VC polymer is deposited at the surface of both electrodes.
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