The dry cell battery is one of the most commonly used types, including AA, 9-volt, and watch batteries. Dry cell batteries are different from wet cells because their electrolytes are contained in a low-moisture paste, while a wet cell has electrolytes contained in a liquid, hence the difference in names. A chemical reaction within the battery creates an electrical charge that flows from inside to an outer circuit that is connected to an electrical device.
What It Is Made Of
Dry cell batteries, regardless of their size, typically have the same basic components. At the center of each is a rod called a cathode, which is often made of carbon and surrounded by an electrolyte paste. Different chemicals can be used to create this paste, such as ammonium chloride and manganese dioxide, depending on the type of battery. The cathode and electrolyte paste are wrapped in paper or cardboard and sealed into a metal cylinder called an anode, which is typically made of zinc.
How It Works
The anode in the dry cell battery has two terminals, one that is positive and one that is negative. When a load is connected to the battery's terminals, a chemical reaction occurs between the anode and the paste that produces roughly 1.5 volts of electricity. A pin or "collector" in the middle of the battery conducts this charge out of the battery to an external circuit. This circuit physically connects to the electronic device the battery is in, providing the charge necessary for the device to function.
Each set of anode, electrolyte, and cathode acts as a single cell, and multiple cells can be connected together within one dry cell battery to produce a higher overall voltage. After the load has been connected for a long time, the battery's chemicals break down and no longer produce a charge. Primary batteries should be discarded once they reach this point, while secondary batteries can be recharged through special devices. This effectively reverses the chemical reaction within each cell, allowing the battery to continue working.
Different Types
Alkaline batteries are more popular than their older counterparts because they corrode more slowly and thus produce a charge longer. A less commonly used type of dry cell battery uses silver for the cathode rod. Nickel/Cadmium (NiCd), Nickel Metal Hydride (NiMH), and Lithium-Ion (Li-Ion) batteries are rechargeable, making them popular for use in power-hungry digital cameras and other portable devices.
Proper Handling and Disposal
Batteries frequently contain chemicals that are harmful if released into the environment, and should be recycled properly. Many municipal recycling programs accept batteries, though modern alkaline ones can typically be thrown away with household trash. Consumers should also consider using rechargeable batteries because they can be reused many times and can also be recycled after they no longer hold a charge.