Imagine a world where everything that used electricity had to be plugged in.
Flashlights, hearing aids, cell phones and other portable devices would be tethered to electrical outlets, rendering them awkward and cumbersome. Cars couldn't be started with the simple turn of a key; a strenuous cranking would be required to get the pistons moving. Wires would be strung everywhere, creating a safety hazard and an unsightly mess. Thankfully, batteries provide us with a mobile source of power that makes many modern conveniences possible.
While there are many different types of batteries, the basic concept by which they function remains the same. When a device is connected to a battery, a reaction occurs that produces electrical energy. This is known as an electrochemical reaction. Italian physicist Count Alessandro Volta first discovered this process in 1799 when he created a simple battery from metal plates and brine-soaked cardboard or paper. Since then, scientists have greatly improved upon Volta's original design to create batteries made from a variety of materials that come in a multitude of sizes.
Today, batteries are all around us. They power our wristwatches for months at a time. They keep our alarm clocks and telephones working, even if the electricity goes out. They run our smoke detectors, electric razors, power drills, mp3 players, thermostats -- and the list goes on. If you're reading this article on your laptop or smartphone, you may even be using batteries right now! However, because these portable power packs are so prevalent, it's very easy to take them for granted. This article will give you a greater appreciation for batteries by exploring their history, as well as the basic parts, reactions and processes that make them work. So cut that cord and click through our informative guide to charge up your knowledge of batteries.
Batteries have been around longer than you may think. In 1938, archaeologist Wilhelm Konig discovered some peculiar clay pots while digging at Khujut Rabu, just outside of present-day Baghdad, Iraq. The jars, which measure approximately 5 inches (12.7 centimeters) long, contained an iron rod encased in copper and dated from about 200 B.C. Tests suggested that the vessels had once been filled with an acidic substance like vinegar or wine, leading Konig to believe that these vessels were ancient batteries. Since this discovery, scholars have produced replicas of the pots that are in fact capable of producing an electric charge. These "Baghdad batteries" may have been used for religious rituals, medicinal purposes, or even electroplating.
In 1799, Italian physicist Alessandro Volta created the first battery 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. However, there were some drawbacks to Volta's invention. The height at which the layers could be stacked was limited because the weight of the pile would squeeze the brine out of the pasteboard or cloth. The metal discs also tended to corrode quickly, shortening the life of the battery. Despite these shortcomings, the SI unit of electromotive force is now called a volt in honor of Volta's achievement.
Take a look at any battery, and you'll notice that it has two terminals. One terminal is marked (+), or positive, while the other is marked (-), or negative. In normal flashlight batteries, like AA, C or D cell, the terminals are located on the ends. On a 9-volt or car battery, however, the terminals are situated next to each other on the top of the unit. If you connect a wire between the two terminals, the electrons will flow from the negative end to the positive end as fast as they can. This will quickly wear out the battery and can also be dangerous, particularly on larger batteries. To properly harness the electric charge produced by a battery, you must connect it to a load. The load might be something like a light bulb, a motor or an electronic circuit like a radio.
The internal workings of a battery are typically housed within a metal or plastic case. Inside this case are a cathode, which connects to the positive terminal, and an anode, which connects to the negative terminal. These components, more generally known as electrodes, occupy most of the space in a battery and are the place where the chemical reactions occur. A separator creates a barrier between the cathode and anode, preventing the electrodes from touching while allowing electrical charge to flow freely between them. The medium that allows the electric charge to flow between the cathode and anode is known as the electrolyte. Finally, the collector conducts the charge to the outside of the battery and through the load.