Zinc-air batteries are primary cells, i.e. non-rechargeable batteries. Their chemical reaction is based on the oxidation of zinc. Zinc-air batteries belong to the metal-air batteries and use a relatively old technology, which is often used in button cells, but also in other battery shapes and sizes The considerations extend far beyond the use of classic batteries to the energy source for motor vehicles.
The structure of zinc-air batteriesIn terms of construction, zinc-air batteries consist of an anode made of zinc powder, the cathode is formed from atmospheric oxygen, the electrolyte is caustic potash solution and a graphite rod, graphite powder or a carbon grid serves as the catalyst. In the frequently chosen design of the button cell, a separator and the carbon grid are located between the zinc powder and the oxygen. The oxygen is supplied through small air holes which are sealed by adhesive tapes until they are used. As soon as the air holes are opened and oxygen is supplied, oxidation of the zinc with the oxygen takes place and the zinc-air battery delivers the nominal voltage. Wh/kg.
Since zinc-air batteries react in the presence of oxygen to produce energy, air sealing is particularly important during storage and before use, otherwise the battery will self-discharge. If there is no air supply, the self-discharge is about 3% per year. Zinc-air batteries are used as button cells in hearing aids. Their use in wristwatches is limited because they are often sealed airtight.