Batteries may be found anywhere. The modern world is reliant on these portable energy sources, which can be found in anything from mobile gadgets to hearing aids to automobiles.
Despite their pervasiveness in people's daily lives, batteries are sometimes disregarded.
A battery's anatomy
Most batteries are made up of three fundamental components: electrodes, an electrolyte, and a separator.
Every battery contains two electrodes. They are both constructed of conductive materials, yet they serve different functions. One electrode, known as the cathode, is connected to the battery's positive end and is where electrical current exits (or electrons enter) the battery during discharge, which is when the battery is used to power anything.
The opposite electrode, known as the anode, is connected to the battery's negative end and is where electrical current enters (or electrons leave) the battery during discharge.
The electrolyte is found both between and within these electrodes. A liquid or gel-like material containing electrically charged particles, called ions. Ions react with the electrode materials, causing chemical processes that allow a battery to create an electric current.
The separator, the battery's final component, is rather simple. The separator's function is to keep the anode and cathode separated inside the battery.
Without a separator, the two electrodes would make contact, resulting in a short circuit and preventing the battery from functioning correctly.
Consider inserting alkaline batteries, such as double AAs, into a flashlight to see how a battery works. When you put those batteries in the flashlight and turn it on, you're actually completing a circuit. The chemical energy contained in the battery is converted to electrical energy, which goes from the battery to the base of the flashlight's bulb and causes it to light up. The electric current then re-enters the battery, albeit at the other end from where it initially exited.
The battery's components all work together to power the flashlight. The electrodes of the battery are made up of atoms of various conducting materials. In an alkaline battery, for example, the anode is commonly constructed of zinc, and manganese dioxide serves as the cathode. Ions are present in the electrolyte between and inside those electrodes. When these ions come into contact with the atoms of the electrodes, specific electrochemical processes occur between the ions and the atoms of the electrodes.
The chemical reactions that occur in the electrodes are known as oxidation-reduction (redox) reactions. The cathode is regarded as the oxidizing agent in a battery because it steals electrons from the anode. The anode is known as the reducing agent because it loses electrons.
Finally, these reactions cause the flow of ions between the anode and the cathode, as well as the release of electrons from the electrode's atoms.
These liberated electrons concentrate inside an alkaline battery's anode (the bottom, flat component). As a result, the anode gets negatively charged as electrons are released, while the cathode becomes positively charged as electrons (which are negatively charged) are consumed. Because of the charge difference, electrons gravitate toward the positively charged cathode. They can't go into the battery, though, because the separator prohibits them from doing so.
Everything changes when you turn on your flashlight. The electrons can now go to the cathode. They must first travel through the base of your flashlight's bulb.
When the electric current re-enters the battery via the top of the cell at the cathode, the circuit is complete.
For primary batteries, such as those used in flashlights, the reactions that fuel the battery will ultimately cease, which means that the electrons that give the battery with its charge will no longer provide an electrical current. The battery is discharged or "dead" when this occurs.
Such batteries must be discarded since the electrochemical processes that caused the battery to create energy cannot be reversed. The electrochemical reactions that occur within secondary, or rechargeable, batteries, on the other hand, may be reversed by delivering electrical energy to the battery.
This occurs, for example, when you plug your smartphone battery into a charger that is linked to a power source.
Lithium-ion (Li-ion) batteries, which power most consumer electronic gadgets, are among the most prevalent secondary batteries in use today. These batteries generally have a carbon anode, a lithium cobalt dioxide cathode, and an electrolyte comprising a lithium salt in an organic solvent. Nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries are also rechargeable and can be used in electric cars and cordless power equipment. Lead-acid (Pb-acid) batteries are extensively used for starting, lighting, and ignition in automobiles and other vehicles.
All of these rechargeable batteries work on the same basic idea. When you connect the battery to a power source, the flow of electrons reverses and the anode and cathode return to their original states.
Although all batteries function in much the same manner, several types of batteries have distinct characteristics. Here are a few terminologies that are frequently used in battery discussions:
Voltage: Voltage, also known as nominal cell voltage, is the amount of electrical force, or pressure, at which free electrons migrate from the positive end of the battery to the negative end of the battery, according to Sastry. A current goes more slowly (with less electrical force) out of a lower-voltage battery than a higher-voltage battery (with greater electrical force). A flashlight's batteries normally have a voltage of 1.5 volts. If a flashlight utilizes two batteries in series, the aggregate voltage of these batteries, or cells, is 3 volts.
Lead-acid batteries, which are commonly used in nonelectric vehicles, typically have a voltage of 2.0 volts. However, in a car battery, six of these cells are normally linked in series, which is why such batteries are commonly referred to as 12-volt batteries.
The most popular form of Li-ion battery found in consumer devices is lithium-cobalt-oxide batteries, which have a nominal voltage of roughly 3.7 volts.
Amps: An amp, also known as an ampere, is a unit of measurement for electrical current, or the number of electrons passing through a circuit in a certain time period.
According to a post by Rice University's electrical and computer engineering department, capacity, or cell capacity, is measured in ampere-hours, which is the number of hours the battery can supply a specific amount of electrical current before its voltage drops below a certain threshold.
A 9-volt alkaline battery – the type used in portable radios — is rated at 1 ampere-hour, which indicates it can produce one amp of current continuously for one hour before reaching the voltage threshold and being declared drained.
Power density: The amount of power a battery can supply per unit weight is referred to as its power density. Power density is significant for electric vehicles since it indicates how quickly the automobile can accelerate from 0 to 60 mph (97 km/h). Engineers are always attempting to reduce the size of batteries without reducing their power density.