What Is a Silver-Oxide Battery?

Silver oxide battery, also known as silver-zinc battery or zinc-silver oxide battery, is a battery with silver oxide as the positive electrode, zinc as the negative electrode, and alkaline solution as the electrolyte. It has the advantages of smooth discharge and high energy-to-weight ratio. However, because of the higher cost of silver, it is generally used as a button battery, or used in specific occasions that have higher requirements and can withstand this high cost. Certain torpedoes or submarines.

Like a mercury battery, a silver oxide battery has a very smooth discharge voltage curve. But its working voltage is 1.5v (open circuit voltage is 1.6v). The ampere-hour capacity of a silver oxide battery is about the same as a mercury battery. Silver oxide batteries are an important power source for hearing aids and meters. The positive electrode (cathode) is a depolarized oxide of silver oxide and manganese dioxide. With different applications, the composition of the mixture is different; the negative electrode is zinc. Silver oxide batteries for hearing aids (requires low leakage current and long life), the electrolyte is strong alkaline potassium hydroxide to enhance its energy density; silver oxide batteries for electronic watches (very low Leakage current, extremely long service life), and its electrolyte is sodium hydroxide (50-diumhydroxide) with better stability.

Of the common silver oxide battery models, the beginning is generally SR, which is caused by

The voltage of the silver oxide battery is high. The nominal voltage of the silver oxide primary battery is 1.55v, which is higher than 1.5v of the alkaline battery and 1.35v of the mercury battery. During the discharge process, the curve of the voltage versus the discharge time is flat, that is, it can maintain near the same voltage for a long time. It is different from the case that the alkaline battery gradually decreases its voltage as the battery power decreases. ^[2]

The chemical reaction is as follows:

Zn + Ag ₂ O ZnO + 2Ag

The positive and negative reactions are:

Positive electrode: Ag ₂ O + H ₂ O + 2e- 2Ag + 2OH-

Negative electrode: Zn + 2OH- ZnO + H ₂ O + 2e-

Because the zinc in the negative electrode can react with the components in the electrolyte, it is corroded and consumed. This will not only reduce the available capacity of the battery, but also generate hydrogen, which will cause the internal pressure of the battery to increase and expand. In order to suppress this effect, the zinc surface is usually covered with a small amount of mercury, but it also causes mercury pollution to the environment caused by waste batteries. The battery clips of silver oxide batteries can also be recycled. Therefore, silver oxide batteries should be recycled effectively to avoid polluting the environment. ^[2]