title: Anodic Behavior of the Aluminum Current Collector in Imide-Based Electrolytes: Influence of Solvent, Operating Temperature, and Native Oxide-Layer Thickness.
abstract: The inability of imide salts to form a sufficiently effective passivation layer on aluminum current collectors is one of the main obstacles that limit their broad application in electrochemical energy-storage systems. However, under certain circumstances, the use of electrolytes with imide electrolyte salts in combination with the aluminum current collector is possible. In this contribution, the stability of the aluminum current collector in electrolytes containing either lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) or lithium fluorosulfonyl-(trifluoromethanesulfonyl) imide (LiFTFSI) as conductive salt was investigated by electrochemical techniques, that is, cyclic voltammetry (CV) and chronocoulometry (CC) in either room-temperature ionic liquids or in ethyl methyl sulfone. In particular, the influence of the solvent, operating temperature, and thickness of the native oxide layer of aluminum on the pit formation at the aluminum current collector surface was studied by means of scanning electron microscopy. In general, a more pronounced aluminum dissolution and pit formation was found at elevated temperatures as well as in solvents with a high dielectric constant. An enhanced thickness of the native aluminum oxide layer increases the oxidative stability versus dissolution. Furthermore, we found a different reaction rate depending on dwell time at the upper cut-off potential for aluminum dissolution in TFSI- and FTFSI-based electrolytes during the CC measurements; the use of LiFTFSI facilitated the dissolution of aluminum compared to LiTFSI. Overall, the mechanism of anodic aluminum dissolution is based on: i) the attack of the Al2O3surface by acidic species and ii) the dissolution of bare aluminum into the electrolyte, which, in turn, is influenced by the electrolyte's dielectric constant.
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Meister
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Qi
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Kloepsch
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Krämer
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Streipert
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.|Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Winter
authors.affiliation: University of Münster, MEET Battery Research Center, Institute of Physical Chemistry, Corrensstraße 46, 48149, Münster, Germany.
authors.forename: Tobias
authors.identifier: 0000-0002-2097-5193
authors.initials: T
authors.lastname: Placke
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D004573:Electrolytes / Q000737:chemistry*; D007094:Imides / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D012997:Solvents; D013696:Temperature
chemical_list: D004573:Electrolytes; D007094:Imides; D010087:Oxides; D012997:Solvents; D000535:Aluminum
keywords: aluminum current collector; anodic dissolution; ionic liquids; lithium-ion battery; native oxide layer