Battery Works Battery (Also Called

¶ … Battery Works battery (also called electric cell) is a device that converts chemical energy into electricity. It consists of a container full of chemicals that produce electrons as a result of chemical reaction. It also has two terminals, one positive (+) and the other negative (-).When the two terminals of a battery are connected through a wire or a device such as a light bulb or a motor is connected across the terminals, the chemical reaction inside the battery starts and electrons flow from the negative terminal to the positive terminal, providing the required electric current to run the device. (Brain, 2007)

We can visualize the process taking place inside a battery by examining what an electric current is. Each atom consists of a tiny, positively charged nucleus surrounded by a number of even smaller, negatively charged particles called electrons. The charge on the nucleus is equal in size to the total charge of all the electrons in an atom, which makes atoms electrically neutral. However, atoms can lose or gain electrons to become positively or negatively charged; in such a state they are called ions ("How do..." n.d.) the top wire in the figure below shows an electrically neutral wire in which the positively charged ions (red) and the negative charges (blue) are balanced. However, if the negatively charged electrons get concentrated at one end of the wire, they would rush towards the positively charged ions at the other end of the wire to balance out the positive charges. Such a flow of negatively charged electrons appears as an electric current in the wire as shown in the wire at bottom below:

Such an imbalance of the negatively and positively charged ions make electric current flow between the negative and positive terminals of the battery.

Chemical Reaction Inside a Battery: Although there are different types of batteries such as zinc-carbon battery (the commonly used, inexpensive dry battery cells), lead acid battery (used in automobiles) or the Nickel-metal hydride battery (rechargeable, dry batteries), the principle of how they work is the same. Each cell inside a battery consists of a liquid, paste or solid "electrolyte," a "positive electrode," and a "negative electrode." The electrolyte is an ionic conductor; one of the electrodes reacts, producing electrons, while the other accepts electrons. When the electrodes are connected to a device to be powered (called a load) an electrical current flows. ("Battery," 2007)

As an example, in one cell of a lead-acid battery used in automobiles, the process producing the current takes place as follows:

One plate inside the cell is made of lead; the other plate is made of lead dioxide, and it contains a strong sulfuric acid electrolyte in which both plates are immersed.

Lead combines with SO4 to create lead sulfate (PbSO4) plus one electron.

Lead dioxide, hydrogen ions and SO4 ions, plus electrons from the lead plate, create PbSO4 and water on the lead dioxide plate.

As the battery discharges, both plates build up PbSO4 (lead sulfate), and water builds up in the acid. (Brain, 2007)