So how do batteries work?
Well the first part we will need to look at is the main parts of a battery and what exactly a battery is made up of. All batteries contain one or more cells, but people often use the terms battery and cell interchangeably. A cell is just the working chemical unit inside a battery; one battery can contain any number of cells. A cell has three main parts: a positive electrode (terminal), a negative electrode, and a liquid or solid separating them called the electrolyte. When a battery is connected to an electric circuit, a chemical reaction takes place in the electrolyte causing ions (in this case, atoms with a positive electrical charge) to flow through it one way, with electrons (particles with a negative charge) flowing through the outer circuit in the other direction. This movement of electric charge makes an electric current flow through the cell and through the circuit it is connected to.
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.
A Little Battery history
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.
The next breakthrough in battery technology came in 1836 when English chemist John Frederick Daniell 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 the zinc plate was hung in the jar, and a zinc sulfate solution was added. Because copper sulfate is denser than zinc sulfate, the zinc solution floated to the top of the copper solution and surrounded the zinc plate. The wire connected to the zinc plate represented the negative terminal, while the one leading from the copper plate was the positive terminal. Obviously, this arrangement would not have functioned well in a flashlight, but for stationary applications it worked just fine. In fact, the Daniell cell was a common way to power doorbells and telephones before electrical generation was perfected.
The Anatomy of a Battery/Cell
If you look at a battery you will 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.
On the next page, we’ll explore how the cathode, anode, electrolyte, separator and collector work together to produce an electrical current and keep your portable devices going strong.
A lot happens inside a battery when you pop it into your flashlight, remote control or other wire-free device. While the processes by which they produce electricity differ slightly from battery to battery, the basic idea remains the same.
When a load completes the circuit between the two terminals, the battery produces electricity through a series of electromagnetic reactions between the anode, cathode and electrolyte. The anode experiences an oxidation reaction in which two or more ions (electrically charged atoms or molecules) from the electrolyte combine with the anode, producing a compound and releasing one or more electrons. At the same time, the cathode goes through a reduction reaction in which the cathode substance, ions and free electrons also combine to form compounds. While this action may sound complicated, it’s actually very simple: The reaction in the anode creates electrons, and the reaction in the cathode absorbs them. The net product is electricity. The battery will continue to produce electricity until one or both of the electrodes run out of the substance necessary for the reactions to occur.
Modern batteries use a variety of chemicals to power their reactions. Common battery chemistries include:
> Zinc-carbon battery: The zinc-carbon chemistry is common in many inexpensive AAA, AA, C and D dry cell batteries. The anode is zinc, the cathode is manganese dioxide, and the electrolyte is ammonium chloride or zinc chloride.
> Alkaline battery: This chemistry is also common in AA, C and D dry cell batteries. The cathode is composed of a manganese dioxide mixture, while the anode is a zinc powder. It gets its name from the potassium hydroxide electrolyte, which is an alkaline substance.
> Lithium-ion battery (rechargeable): Lithium chemistry is often used in high-performance devices, such as cell phones, digital cameras and even electric cars. A variety of substances are used in lithium batteries, but a common combination is a lithium cobalt oxide cathode and a carbon anode.
> Lead-acid battery (rechargeable): This is the chemistry used in a typical car battery. The electrodes are usually made of lead dioxide and metallic lead, while the electrolyte is a sulfuric acid solution.
How to make your own battery
There are lots of easy ways to make homemade batteries. Basically, any two different kinds of metal can be placed in a conducting solution and you get a battery. Familiar homemade batteries include sticking copper and zinc strips into a lemon or a potato to make a battery.
One quick battery is made from a coke can, the cola from the can, and some copper.
Ok so if you are unsure and don’t believe just how easy this is, here are some step guides
Step One
Pour the drink into a plastic cup and empty the can completely.
Step Two
CAREFULLY!!!! cut a small strip of the Aluminum can. This can MUST be made out of Aluminum. You can find out what it is made out of by reading the side of the can. The cans are normally made out of Aluminum or another metal mixture (tin, steel).
Step Three
Once you have cut a slither of Aluminum from the can about one inch wide by say 3-4 inches long, you will want to get some sandpaper and sand the Aluminum strip down thoroughly. The Aluminum will have a coating of plastic or some oxide to prevent reactions with the content (soda drink).
Step Four
You will Need to acquire a similar sized piece of other metal. I would suggest copper, as this has good conductivity. Once again, clean the copper strip with sandpaper to ensure it is clean of any contaminants. Once ready, bend the the metal strips into the liquid as shown below. Here is a quick question for you to try. Does altering the length or size of the metal strips increase the voltage produced? Remember to always write a science journal of your findings and be specific of ALL measurements. YOU CAN NOT RECORD TOO MUCH INFORMATION!!!
Last Step
Test it. If you do not have the device shown above, this is a volt metre with some crocodile clips and some standard cabling (which will often come with a volt metre). They are quite cheap, check amazon or click here for google results, really you just want a cheap one.
Now that you have got this running, it is time to test different liquids and materials to find which is the best (remembering to record your findings). Some suggestions would be different energy drinks, fruits, salt water, mud.
How to make a Lemon Battery
Electrochemistry – Salt Bridge Battery explained (detailed)
How is an Alkaline Battery made
How Batteries Work
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