Quantitative evaluation of LiPF6 as corrosion inhibiting additive for Al in LiTFSI-based battery electrolytes – An on-line mass spectrometric study

Autor: Christopher Behling, Janik Lüchtefeld, Karl J.J. Mayrhofer, Balázs B. Berkes
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Electrochemistry Communications, Vol 159, Iss , Pp 107646- (2024)
Druh dokumentu: article
ISSN: 1388-2481
DOI: 10.1016/j.elecom.2023.107646
Popis: Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is a promising candidate for future lithium-ion battery (LIB) electrolytes because of its increased stability and ionic conductivity. One major drawback of this salt, however, is its ability to dissolve Al, leading to a degradation of current collectors in LIBs over time. Surface passivating additives can reduce or even completely suppress the dissolution. A truly cost and material-efficient suppression, however, can only be achieved by identifying the ideal (i.e., minimal) amount of additive. Therefore, quantifying the dissolution-suppressing effect of additives is necessary to create an optimum electrolyte mixture. In this work, we examine the influence of lithium hexafluorophosphate (LiPF6) addition to LiTFSI-based electrolytes via cyclic voltammetry (CV) in an electroanalytical flow cell (EFC) coupled on-line to an inductively coupled plasma mass spectrometer (ICP-MS) for continuous downstream elemental analysis. This setup allows the potential resolved quantification of Al dissolution with unprecedented precision in real-time. With that, we found that already very small amounts of 0.02 M LiPF6 added to 0.98 M LiTFSI will drastically reduce the total dissolved amount of Al during one CV cycle by a factor of ∼ 20, while electrolytes containing 0.30 M LiPF6 (and 0.70 M LiTFSI) completely suppress the dissolution of Al. These findings allow the substitution of large portions of LiPF6, enabling the production of safer LIBs without risking current collector degradation.
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