How do rechargeable batteries work ?

How do rechargeable batteries work ?With the rise in portable devices such as laptops, cell phones, MP3 players and cordless power tools, the need for rechargeable batteries has grown substantially in recent years. Rechargeable batteries have been around since 1859, when French physicist Gaston Plante invented the lead acid cell. With a lead anode, a lead dioxide cathode and a sulfuric acid electrolyte, the Plante battery was a precursor to the modern-day car battery.

Rechargeable batteries consist of one or more electrochemical cells and are a type of energy accumulator. It is known as a secondary cell as it has the ability to be recharged and reused. The reactions inside the cell that causes the batteries to provide power can be made using a number of different materials. This reaction can be reversed using electricity for a number of uses. When the batteries are recharged, the positive active material is oxidized and the negative material is reduced. The electrolyte between the two materials could serve as a as a simple buffer for internal ion flow between the electrodes or may play an active part in the electrochemical reaction. The batteries require a proper battery charger that uses either AC or DC electricity to charge the batteries. Depending on the charger, batteries may take anywhere from 4-14 hours to charge. Though rechargeable batteries can be reused multiple times, it often has a limited lifecycle and can only be recharged a number of times. Rechargeable batteries have a higher initial cost, but are cheaper in the long-run. Rechargeable batteries are made using a number of different materials such as Lead–acid, Nickel–iron, Nickel–zinc, Lithium-ion, sodium-ion, etc. The most common rechargeable batteries are Nickel–cadmium battery (NiCd), Nickel–metal hydride battery (NiMH), Lithium-ion battery and Lithium-ion polymer battery. These batteries are becoming increasingly popular in many applications including cell phones, electric vehicles, motorized wheel chairs, flashlights, etc.

What happens inside a typical battery—like the one in a flashlight? When you click the power switch, you’re giving the green light to chemical reactions inside the battery. As the current starts flowing, the cells (power-generating compartments) inside the battery begin to transform themselves in startling but entirely invisible ways. The chemicals from which their components are made begin to rearrange themselves. Inside each cell, chemical reactions take place involving the two electrical terminals (or electrodes) and a chemical known as the electrolyte that separate them. These chemical reactions cause electrons (the tiny particles inside atoms that carry electricity) to pump around the circuit the battery is connected to, providing power to the flashlight. But the cells inside a battery contain only limited supplies of chemicals so the reactions cannot continue indefinitely. Once the chemicals are depleted, the reactions stop, the electrons cease flowing through the outer circuit, the battery is effectively flat—and your lamp goes out.

The good news is that if you’re using a rechargeable battery, you can make the chemical reactions run in reverse using a battery charger. Charging up a battery is the exact opposite of discharging it: where discharging gives out energy, charging takes energy in and stores it by resetting the battery chemicals to how they were originally. In theory, you can charge and discharge a rechargeable battery any number of times; in practice, even rechargeable batteries degrade over time and there eventually comes a point where they’re no longer willing to store charge. At that point, you have to recycle them or throw them away.

Using and charging batteries is not just about moving energy; it is about transforming energy. As some people may remember from school, energy cannot be created or destroyed ( survey here ) , but it can change form. Charging a battery transforms electrical energy to chemical energy, and using a battery transforms chemical energy into electrical energy. Every time energy changes form, some of the energy is lost. If someone tried to charge one battery with another battery of equal capacity, the two batteries would quickly run out of power because with each charge some of the power would be lost. Because of this loss of energy, using a battery is always going to be a less efficient use of energy than simply plugging into a socket, because plugging in means fewer energy-wasting transformations. That does not mean that batteries are bad, but that battery-powered machines are sometimes less “green” than they might appear to be.


Purchasing rechargeable batteries instead of standard ones is an easy way to show off your green side and demonstrate a bit of concern for the environment. If we all start doing this, we can ease the strain on our landfills without sacrificing our high-tech gadgets.


from Blogger



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