4. Conclusions
The following conclusions have been drawn from the present
study.
1. A pure-zinc electrode (99.9 to 99.95 wt.%) in 10 M
NaOH with inhibitor and complexing agents such as 15 wt.%
sodium citrate, 0.3 wt.% CaO and 0.02 M sodium stannate
provides a good combination of anode and electrolyte for use
in alkaline metal-air batteries and dry cells.
2. Potentiodynamic polarization studies clearly bring out
the fact that the corrosion of pure zinc and its alloys in 10 M
NaOH is mostly under cathodic control. By contrast, the
corrosion of zinc and its alloys in the presence of inhibitor
and complexing agents is mainly under anodic control.
3. Both pure zinc and Zn +0.01 wt.% Mg+0.01 wt.% Pb
alloy have anode efficiencies of 93 to 99% between current
densities of 25 to 125 mA/cm 2.
4. It has been proved that it is possible to use pure zinc or
zinc alloy (Zn+0.01 wt.% Mg+0.01 wt.% Pb) as a good
anode in both alkaline Zn-MnO2--carbon cells and alkaline
Zn-air cells in place of zinc that contains mercury.
5. It is possible to construct both dry cells and metal-air
batteries using the above mercury-free anodes and electrolytes.