Corrosion of Passive Aluminum Anodes in a Chloroaluminate Deep Eutectic Solvent for Secondary Batteries: The Bad, the Good, and the Ugly

David Moser, Philipp Materna, Anna Stark, Judith Lammer, Attila Csík, Jasmin M Abdou, Raphael Dorner, Martin Sterrer, Walter Goessler, Gerald Kothleitner, Bernhard Gollas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The passivity of aluminum is detrimental to its performance as an anode in batteries. Soaking of native oxide-covered aluminum in a chloroaluminate deep eutectic solvent gradually activates the electrode surface, which is reflected in a continuously decreasing open circuit potential. The underlying processes were studied by analyzing the 3 to 7 nm thick layer of native oxide after increasing periods of soaking with secondary neutral mass spectrometry, X-ray photoelectron spectroscopy, and energy-dispersive spectroscopy in a transmission electron microscope. They consistently show permeation of electrolyte species into the layer associated with gradual swelling. After extended periods of soaking at open circuit potentials, local deposits of a range of foreign metals have been found in scanning electron microscopy images of the electrode surface. The pitting corrosion is caused by trace metal ion impurities present in the electrolyte and results in highly nonuniform current density distribution during discharge/charge cycling of battery cells as shown by local deposits of aluminum. The processes during soaking at open circuit potentials have been monitored by electrochemical impedance spectroscopy and could be analyzed by fitting an equivalent circuit model for pitting corrosion.

Original languageEnglish
Pages (from-to)882-892
JournalACS Applied Materials & Interfaces
Issue number1
Early online date27 Dec 2022
Publication statusPublished - Jan 2023


  • aluminum anode
  • aluminum-sulfur battery
  • chloroaluminate electrolyte
  • corrosion
  • local current distribution
  • native oxide
  • pitting
  • trace metal impurities

ASJC Scopus subject areas

  • Materials Science(all)

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)
  • Experimental

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