An alkaline dry battery, also known as an alkaline battery, is a type of disposable battery that uses an alkaline electrolyte as its power source. It is called a "dry battery" because it contains no free-flowing liquid electrolyte. Alkaline batteries are commonly available in the cylindrical shape with a metal jacket and a positive terminal (cap) at one end and a negative terminal (nub) at the other end.
The basic construction of an alkaline dry battery consists of the following components:
1. Cathode (Positive Electrode): The cathode is typically made of manganese dioxide (MnO2) mixed with carbon black and other additives. It acts as the positive electrode, where reduction reactions occur during battery discharge.
2. Anode (Negative Electrode): The anode is usually made of powdered zinc (Zn). It serves as the negative electrode, where oxidation reactions take place during battery discharge.
3. Separator: A separator is placed between the cathode and anode to prevent direct contact and short circuits while allowing the flow of ions.
4. Alkaline Electrolyte: The alkaline electrolyte in an alkaline battery is typically a potassium hydroxide (KOH) solution, which provides the necessary ions for the electrochemical reactions.
When an external load is connected across the positive and negative terminals of the battery, a chemical reaction occurs within the cell. The manganese dioxide (MnO2) at the cathode reacts with water from the electrolyte, producing hydroxyl ions (OH-) and releasing electrons. At the same time, the zinc at the anode reacts with hydroxyl ions and generates zinc oxide (ZnO) and water. The released electrons flow through the external circuit, providing electrical power for the connected device.
Alkaline batteries are known for their high energy density, long shelf life, and relatively stable voltage output during discharge. They are widely used in various consumer electronics, toys, remote controls, flashlights, and many other portable devices that require a reliable and long-lasting power source.