Zinc-carbon batteries service life

Magnesium has been used successfully in a magnesium/manganese dioxide (Mg/MnO,) battery. This battery has two main advantages over the zinc-carbon battery, namely, twice the service life or capacity of the zinc battery of equivalent size and the ability to retain this capacity, during storage, even at elevated temperatures (Table 9.1). This excellent storability is due to a protective film that forms on the surface of the magnesium anode. 

Figure7.1 Battery service life as a function of initial current drain and duty cycle D size carbon-zinc battery (Courtesy of Union Carbide)...

The effective service life of Air/PANI-Zn battery can be greater by several folds than that of conventional alkaline air-zinc batteries owing to the absence in principle of electrolyte carbonization (pH < 7). 

The combination of the effects of self-discharge and gas transfer degradation determines the service life performance of a zinc/air battery. For most applications water transfer is the dominant factor. However, under some conditions electrolyte carbonation and direct oxidation mechanisms can adversely affect performance. 

Table 54.2 Estimated average service life at 21 °C for a selection of Union Carbide Eveready carbon- zinc Leclanche dry cells and batteries, voltage range 1.5-9V... 

Serv ice life at low temperatures is reduced because of decreased chemical activity in the cell. The effects are more pronounced for heavy current drains than for light drains. When a standard carbon-zinc battery has reached a temperature of — 18°C, little service is obtained except at light drains. At —23°C,... 

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