The Zinc Electrode in Alkaline Solutions

Metallic zinc was used as material for the negative electrode in the earliest electrical cell, Volta s pile, and is still employed in a variety of batteries including batteries with alkaline electrolytes. 

The operation of zinc anodes in alkaline solutions (mainly 20-40% KOH) involves specific features. In the anodic dissolution of zinc 

Because, under these conditions, discharge of the battery as a rule results in the production of one OH ion for each electron at the positive electrode (Eiq. 2.7), the secondary process overall occurs without the consumption of alkali, and a solution volume of 1-2 ml/Ah is practically sufficient for the operation of the cell. 

there are two possible modes of utilizing zinc anodes in alkaline solutions. In the first, and older, mode only the primary process is used, with monolithic zinc anodes and a large volume of electrolyte. In the second mode, the secondary process is employed, with powdered zinc anodes at which the true current densities are much lower than at smooth electrodes. 

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The electrochemistry of the zinc electrode in alkaline solution is actually quite complex. Zinc commonly has a coordination number of 4, such as in zinc oxide, or of 6, as in some crystals. The electronic configuration of zinc makes the +2 oxidation state the most stable, although references are occasionally made to monovalent zinc. Zinc has a tendency towards... 

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