4.2.4 Mercury Cell This cell is also m common use and consists of: an outer steel Container as the positive electrode, a cylinder of compressed zinc powder in the centre of the cell as the negative electrode potassium hydroxide as the electrolyte surrounding the zinc plate, and manganese dioxide and carbon as the depolarizing mixture. The cell is constructed so small that it is commonly used in watches, hearing aids, and miniature calculators. Its voltage is 1.35 V. Mercury cell The most important features of the mercury cell are: It can be stored for long periods without losing its charge through local action. It has a very high energy output for its size Its drawbacks are: It is toxic due to high mercury content It is expensive This cell has been replaced with a safer silver oxide cell.