Important Topic of Chemistry: Mercury cell

• The mercury oxide-zinc battery system has been around since the nineteenth century, but it wasn’t widely employed until 1942, when Samuel Ruben invented a balanced mercury cell for military applications such as metal detectors, explosives, and walkie-talkies. The battery system had a longer shelf life (up to ten years) and a consistent voltage output. The battery method was widely used for small electronic devices such as cardiac pacemakers and hearing aids after WWII. Mercury oxide batteries came in a variety of sizes, from tiny button cells for hearing aids to large button cells for electric wristwatches.
• A primary cell, often known as a “Mercury battery” or “Mercury oxide battery,” is a non-rechargeable, non-reusable electrochemical battery. Mercury batteries were the most potent power source for many tiny portable electronic devices such as calculators, watches, hearing aids, digital thermometers, button or coin games, and major appliances such as walkie-talkies during and after WWII. However, on May 13, 1996, Bill Clinton, the President of the United States, signed “The Battery Act” into law. The law’s major goal was to minimize hazardous and heavy metal levels in the environment, such as groundwater, streams, and municipal trash. The popularity of the mercury battery declined as a result of this act.
• The Mercury cell is a dry cell that uses zinc as an anode, mercuric oxide as a cathode, and potassium hydroxide as an electrolyte.

The mercury cells working system

• The Mercury cell is a form of a primary cell that is non-reusable and non-rechargeable, meaning it generates electricity through irreversible chemical reactions.
• The mercury compound works as a cathode in a mercury cell, where the reduction reaction takes place, while the zinc compound acts as an anode, where the oxidation reaction takes place. Sodium hydroxide or potassium hydroxide is an electrolyte that conducts electricity when it ionizes in a molten state.

The Benefits of Mercury Cells vs. Dry Cells

Zinc is converted to zinc chloride in a dry cell during an electrochemical process, making zinc porous. A chemical in the cell leaks out through the porous shell, corroding the metal and reducing the cell’s lifetime. The Mercury cell, on the other hand, does not use any ions in the solution throughout the reactions to change its lifetime.

• Shelf life of up to ten years
• Large capacity for the size
• The output voltage is constant at 1.35V.
• Mercury cells are inexpensive to build with current technology.
• Chlorine can be separated using a mercury cell by removing contaminants such as oxygen, sodium chlorate, and sodium hypochlorite

Limitations

• Environmental and economic concerns – Mercury vapour is toxic to the human body’s organs, including the kidney, neurological system, digestive system, eye, skin, and immune system. A small amount can be extremely harmful to the human body.
• Dangerous to a child’s growth in utero and in the early stages of life.