Methods to control internal interfaces in lithium ion batteries often require sophisticated procedures to deposit coating layers or introduce interphases, which are typically difficult to apply. This particularly holds for protection from parasitic reactions at the current collector, which reflects an internal interface for the electrode composite material and the electrolyte. In this work, electrolyte formulations based on aliphatic cyclic nitriles, cyclopentane-1-carbonitrile and cyclohexane-1-carbonitrile, are introduced that allow for successful suppression of aluminum dissolution and control of internal interfaces under application-relevant conditions. Such nitrile-based electrolytes show higher intrinsic oxidative and thermal stabilities as well as similar capacity retentions in lithium nickel–manganese–cobalt oxide LiNi3/5Mn1/5Co1/5O2 (NMC622)||graphite based full cells compared to the state-of-the-art organic carbonate-based electrolytes, even when bis(trifluoro-methane)sulfonimide lithium salt is utilized. Moreover, the importance of relative permittivity, degree of ion dissociation, and viscosity of the applied electrolyte formulations for the protection of current collector interfaces is emphasized.
Toward adequate control of internal interfaces utilizing nitrile-based electrolytes
Note: This paper is part of the JCP Special Topic on Interfacial Structure and Dynamics for Electrochemical Energy Storage.
C. H. Krause, P. Röring, S. Röser, D. Diddens, J. H. Thienenkamp, I. Cekic-Laskovic, G. Brunklaus, M. Winter; Toward adequate control of internal interfaces utilizing nitrile-based electrolytes. J. Chem. Phys. 7 May 2020; 152 (17): 174701. https://doi.org/10.1063/5.0003098
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