Research On Lead-samarium Alloys For Positive Grid Of VRLA Battery

In this investigation, the influence of the rare earth, samarium, asalloying additive on electrochemical behaviors of pure Pb was studied. Theelectrochemical behaviors of new alloys were determined with XRDpatterns, self-depassivation, linear sweep voltammograms, and ACimpendence, in 4.87 M H₂SO₄ solution(25℃). The research on the Pb-Smalloys (Pb-0.02%Sm, Pb-0.04%Sm, Pb-0.12%Sm) indicates that the oxidefilm formed on alloy surface at 0.9V was thicker than that on pure leadsurface when the alloy contained less than 0.1% samarium, meanwhilesamarium exercised little influence on the conversion of PbSO₄ into PbO₂ inoxide film at charge potential, correspondingly, the electrochemicalimpedance of the oxide film was much larger than that formed on pure lead.However, with the addition of more than 0.1% samarium, the oxide film onthe alloy surface was thinner and samarium obviously promotes theconversion of passive PbSO₄ in oxide film into conductive PbO₂. ACimpendence experimental shows that samarium can more greatly inhibit thegrowth of passivation layer and decrease the electrochemical impedance ofthe film with higher content samarium.