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Article Dans Une Revue Thin Solid Films Année : 2004

In situ ellipsometric and electrochemical monitoring of the oxidation of a Pb–Ca–Sn alloy used in the lead acid batteries

Résumé

The oxidation process of the Pb-0.08 wt.% Ca-1.2 wt.% Sn alloy was investigated by in situ spectroscopic ellipsometry measurements, combined with electrochemical measurements. The evolutions of the electrochemical and optical parameters show a mechanism of the film growth in two parts. In the first 10 min, the ellipsometric spectra exhibit large variations, whereas the measured current is approximately 0.3 mA cm−2. During this complex step, the surface topography is continuously changing. This stage corresponds to the growth of lead sulfate crystals, which is then oxidized in a thin and flat PbO2 layer, as confirmed by ex situ X-ray diffraction and scanning electron microscopy analysis. The second part is identified by a rapid and important decrease of the current, down to a low and steady value of approximately 0.01 mA cm−2. At once, the optical spectra vary slightly. A duplex layer model has been used to interpret spectroscopic ellipsometric measurements. The upper layer is likely composed of β-PbO2 as suggested by ex situ X-ray diffraction analysis. This model indicates a total thickness of the film approximately 480 nm at the end of the polarization (24 h).

Dates et versions

hal-02900547 , version 1 (16-07-2020)

Identifiants

Citer

N. Stein, G. Bourguignon, L. Raboin, L. Broch, L. Johann, et al.. In situ ellipsometric and electrochemical monitoring of the oxidation of a Pb–Ca–Sn alloy used in the lead acid batteries. Thin Solid Films, 2004, 455-456, pp.735-741. ⟨10.1016/j.tsf.2003.11.259⟩. ⟨hal-02900547⟩
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