Corrosion of Lead-Acid Battery Electrodes in Sulphuric Acid

solution. Thus, corrosion was more intense in the oxygenated acid
solution as compared with the deaerated acid solution.
2- The corrosion potentials and the corrosion current densities changed
considerably in the presence of the additives which involved :-
1, H3PO4 ( 11g dm -3 ),
2, A mixture of ( H3PO4(11g dm -3 )+ FeSO4(0.2 g dm -3 )),
3, NaCl (4 g dm -3 ) and ,
4, FeSO4 (0.2 g dm -3 ).
In the stirred and the un-stirred oxygenated 0.56M sulphuric acid solution
in the temperature range (298-318)K using the following working
electrodes:
1, lead alloy electrode,
2, grid lead electrode,
3, cured positive electrode, and ,
4, cured negative electrode.
Values of the corrosion potential (Ec) became more negative in the
presence of H3PO4 and less negative with NaCl additives, the values of the
corrosion current densities for all the electrodes were higher with NaCl
and lower with H3PO4 in the both media.
3- The protection efficiency (p%) was investigated for the additives in
the stirred and the un-stirred oxygenated 0.56M sulphuric acid
solution. Maximum values of p% were attained with H3PO4 and the
minimum with NaCl.
4- Values of the thermodynamic quantities (DG, DW and DH) were
estimated for the corrosion of the electrodes. DG values were more
negative in the deaerated acid solution in the absence of additives. In the
presence of the H3PO4, DG values were more negative while in the
presence of NaCl the values were less negative indicating a greater
corrosion feasibility in the former and smaller in the latter cases. DW