Alkaline Dry Cell Vs. Ordinary Dry Cell

Dry Cell Construction

The basic construction of a dry cell battery is the same regardless of its size. The positive and negative terminals are on the outside of the battery. In the center is the cathode, a rod made of metal or graphite. Surrounding the battery under the outside casing is the anode, usually made of zinc. Between the cathode and anode, separated by a non-conductive material, is the electrolyte, a moist paste that can be made from a variety of materials.

When a device, such as a flashlight, is connected to the external positive and negative terminals, electrons flow from the anode (negative) through the electrolyte, then through the connected device to the cathode, completing the circuit and powering the device. In a regular zinc dry cell battery, the anode is zinc and the electrolyte is an acidic mixture of ammonium chloride or zinc chloride and manganese dioxide. In an alkaline battery, the anode is usually zinc powder and the electrolyte is a potassium hydroxide mixture, which is alkaline (the opposite of acidic), hence the name alkaline battery.

Alkaline batteries cost more than zinc batteries, but their per-use cost is less. In a zinc battery, the acidic electrolyte causes the zinc anode to deteriorate much more quickly than the alkaline electrolyte in an alkaline battery. In the alkaline battery, the anode is zinc powder that provides more surface area and greater longevity than solid zinc. Because of their chemical makeup, alkaline batteries maintain a consistent source of power for a longer period of time.

Some alkaline batteries are rechargeable, so they can be used indefinitely. The recharging process reverses the electron flow and restores the zinc anode. Other types of batteries are mercury and lithium ion, which are more expensive. Cost and the use to which the battery will be put are the determining factors in deciding which battery to use.