Leady oxide (LO) containing different amounts of mineral additive
(0e15 wt. % (w/o)) was mixed with water and 1.40 s.g. H2SO4
in a ratio equal to 5% H2SO4/LO). The mixtures were homogenized
during 30 min and cured 3BS pastes were obtained. The formation
of the mixture was achieved by the employment of a tubular
electrode. Before each experiment, the PbeSb spine was previously
polarized at 1.3 V/Hg/Hg2SO4/saturated K2SO4 in 1.28 s.g. H2SO4
solution so that a conductive anodic layer of PbO2 is obtained. This
layer ensures the contact between the spine and 3BS and initiates
its conversion to PbO2. Each electrode is filled with 3BS powder. All
electrodes are formed in 1.05 s.g H2SO4 solution. The electrodes
were polarized at a constant current of 50 mA until the complete
mass of 3BS is totally converted to a brownish-black PbO2 powder.