Batteries go back much longer than most people think. Clay pots were found outside of Baghdad dating from 200 B.C. They contained an iron rod surrounded by copper sheathing. Testing revealed that the vessels had originally been filled with an acidic liquid like vinegar, leading scientists to believe that these ancient vessels were among the first batteries.

In 1799, Italian physicist Alessandro Volta created one of the first batteries by stacking alternating layers of zinc, brine-soaked pasteboard or cloth, and silver. This arrangement, called a voltaic pile, was not the first device to create electricity, but it was the first to emit a steady, lasting current.

The next breakthrough in battery technology came in 1836, when an English chemist invented the Daniell cell. In this early battery, a copper plate was placed at the bottom of a glass jar and a copper sulfate solution was poured over the plate to half-fill the jar. Then a zinc plate was hung in the jar, and a zinc sulfate solution was added. Early on, this device was a common way to power doorbells and telephones.

By 1898, the Colombia Dry Cell, a zinc-carbon battery became widely available. The manufacturer, National Carbon later changed its name to Eveready, which produces the Energizer brand.

There are three basic components in a battery: an anode, a cathode (commonly called electrodes) and an electrolyte. The electrolyte is a chemical that allows the flow of electrons from the anode (plus) to the cathode (minus). It puts the different metals of the anode and cathode into contact with one another, causing a reaction which converts stored chemical energy into useful electrical energy. When a load, such as a light bulb or motor is connected to the battery, the chemical reaction causes a current of electrical energy through the load, creating things like heat, light or motion. Batteries can only produce direct current (DC). Alternating current (AC) such as found in your house must be made using an inverter which converts DC to AC, or by a generator.

All batteries work on the same basic principle – chemistry. They use a variety of chemicals to power their reactions. Common batteries include:

Lead-acid battery (rechargeable): These have been around for more than 150 years, and are still used today in most autos. The electrodes are usually made of lead dioxide and metallic lead, and the electrolyte is sulfuric acid. They are relatively inexpensive to produce and can deliver high current, like that required for a starter.

Zinc-carbon battery (not rechargeable): This common battery has been used for years in flashlights. The anode is zinc, and the cathode is manganese dioxide. The electrolyte is ammonium chloride or zinc chloride.

Alkaline battery (not rechargeable): In recent years, these have replaced zinc-carbon. They can last up to eight times longer. The cathode is made of manganese dioxide, and the anode is zinc powder. The electrolyte is potassium hydroxide, which is an alkaline substance and gives the battery its name.

Lithium-ion battery (rechargeable): High-performance devices, such as cell phones, digital cameras and even electric cars have driven the development and use of these batteries. Many types of substances are used in lithium batteries, a common combination being a lithium-cobalt oxide cathode and a carbon anode.

As you can see, there are many different types and sizes of batteries. They all function on the same concept; a device that stores potential energy in the form of chemical energy, and is able to convert that energy into electricity by a chemical reaction.

If the battery is “one-shot” or disposable, it will keep going until it runs out of electrolyte. These batteries will only work in one direction (discharge), and are not designed to be recharged. In many other types of batteries, the reaction can be reversed; they can be recharged over and over, using a charger that you plug into a power source, like a wall socket, or the alternator in your car.

Researchers are currently working on a battery in which the electrodes would be lithium and oxygen from the air. Such a remarkable advancement would dramatically decrease battery weight and could deliver five to 10 times the energy of existing lithium-ion batteries. Though this technology still has a number of obstacles to overcome, it could one day revolutionize the electric car industry. Another source being developed for use in cars is the fuel cell, a space-age spin-off. It is actually not a battery, but more like a power source utilizing hydrogen and oxygen as fuel.

Those who would like to ask me questions about any other science topic may e-mail inquiries to lynn@thesylvaherald.com.

Marcus Goodkind of Tuckasegee, a retired aerospace engineer, worked with the National Aeronautics and Space Administration as a manager at Kennedy Space Center on all the manned programs from Mercury to Shuttle, including Apollo 11, the first manned lunar landing.