Ti/Cr(III) conversion coating on aluminium foil for lithium-ion battery package

ABSTRACT

Trivalent chromium (Cr(III)) was added into a titanium (Ti)-based solution in this study to prepare Ti/Cr(III) conversion coatings on the aluminium (Al) foil for lithium-ion battery package. Their surface morphology and chemical composition were characterized by field-emission scanning electron microscope (FE-SEM), energy-dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and the adhesive strength between Al foil and hot melt adhesive (modified polypropylene film) were determined. The results reveal that the Ti/Cr(III) conversion coating is mainly composed of Al₂O₃, TiO₂, Cr(OH)₃ and Cr₂O₃, and possesses the best anticorrosive performance with a corrosion current density of 1.05 µA cm⁻², which is one order of magnitude lower than pure Al foil. The adhesive strength between Ti/Cr(III)-treated Al foil and the adhesive is 14.3 N/15 mm with an increase of 250% compared with the pure Al foil, which meets the industry standard (12 N/15 mm).

KEYWORDS:

• Aluminium foil
• trivalent chromium
• conversion coating
• corrosion resistance
• lithium-ion battery package

Acknowledgements

This research is financially supported by the National Natural Science Foundation of China (21764011), the Foundation from Qinghai Science and Technology Department (2020-HZ-808) and Thousand Talents Program of Qinghai Province.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is financially supported by the National Natural Science Foundation of China [grant number 21764011], the Foundation from QingHai Department of Science and Technology [grant number 2020-HZ-808] and Thousand Talents Program of Qinghai Province.