Rechargeable post Li-ion batteries based on aluminum (Al) are gaining attention due to high abundance of Al, the high theoretical volumetric capacity, and high safety associated with the low flammability [1,2]. In comparison to Li-ion batteries (LiBs), where the solid-electrolyte interphase (SEI) has been studied for decades, little is known on SEI formation in dependence of the used electrolyte for Al electrodes.

In this study, we present the electrochemical performance of Al foils with two different thicknesses (0.025 mm and 0.075 mm), which were used as negative electrode in Al-ion batteries in AlCl₃/1-ethyl-3-methylimidazolium chloride [EMIm]Cl electrolyte. Atomic force microscopy (AFM) was used to determine changes in the morphology of Al foils during the charge - discharge process to obtain information on the SEI and its microstructural morphology [3]. Spatially-resolved information on the electrochemical activity of interphase layers on cycled Al foils can be obtained via scanning electrochemical microscopy (SECM), which so far has only be studied at LiBs [4]. First results reveal the correlation between the morphological changes of SEI layer during cycling and its electrochemical behavior depending on the Al foil surface properties, which will be presented and discussed in this contribution.

Key words: Al foil, AFM, microstructure, SEI layer, SECM.

References:

1. Meng-Chang Lin, Ming Gong, Bingan Lu, Yingpeng Wu, Di-Yan Wang, Mingyun Guan, Michael Angell, Changxin Chen, Jiang Yang, Bing-Joe Hwang and Hongjie Dai, Nature, 520, 325–328 (2015).
2. Li, and N.J. Bjerrum, J. Power Sources, 110, 1–10 (2002).
3. Feng Wu, Na Zhu, Ying Bai, Yaning Gao, and Chuan Wu, Green Energy & Environment 3, 71-77, (2018).
4. Bastian Krueger, Luis Balboa, Jan Frederik Dohmann, Martin Winter, Peter Bieker and Gunther Wittstock. ChemElectroChem,7, 3590–3596, (2020).

This work contributes to the research performed at CELEST (Center for Electrochemical Energy Storage Ulm-Karlsruhe) and was funded by the German Research Foundation (DFG) under Project ID 390874152 (POLiS Cluster of Excellence).