The simultaneous electrodeposition of lead and lead dioxide
The simultaneous electrodeposition of both Pb and PbO2 from Pb(NO3)2 solutions onto a Ni substrate has been investigated with particular reference to the influence of different organic addition agents on the nature of the Pb and PbO2 deposit, the porosity of the Pb deposit and the current efficiency for deposition. Plating solutions for Pb based on Pb(NO3)2 that operate at room temperature and up to 50°C have been developed which produce Pb deposits with properties almost equivalent to those from conventional Pb(BF4)2 plating solutions. The effect of certain additives in modifying the adhesion and grain size of PbO2 deposits has also been reported. Pb and PbO2 deposits prepared by electrodeposition from Pb(NO3)2 solutions containing selected organic addition agents were evaluated for use as the active materials in the Pb/HBF4/PbO2 primary battery. Tests have confirmed that the Pb and PbO2 deposits produced by simultaneous electrodeposition from a Pb(NO3)2 solution containing selected addition agents were not as effective in terms of discharge properties, when compared to the PbO2 and Pb deposited separately from conventional plating solutions. However, Pb and PbO2 deposited simultaneously, satisfied the requirements of the active material used in the Pb/HBF4/PbO2 battery. The continuing problem of the varying degrees of adhesion of electrodeposited PbO2 onto etched Ni foils with no significant variation in composition was investigated. The adhesion of PbO2 to etched N1200 foil was found to be good, whilst that to N1270 was proved to be poor. Certain physical and electrochemical properties of foils that exhibited both 'good' and 'bad' adhesion of PbO2 were investigated, in order to ascertain the cause of the adhesion problem. A number of possible reasons for the poor adhesion of PbO2 to certain batches of Ni foil have been examined and a probable explanation for the adhesion failures has been proposed.
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