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How Do Batteries Work? What You Need to Know!

a person's hands holding different kinds of batteries

Imagine living in a world where batteries don’t exist. You’ll be living in a world that has no mobile phones, hearing aids, transistor radios, laptops, electric cars, or any other portable device that you could think of.

Lucky for us, that’s not the case. And we all have Alessandro Volta to thank, seeing as he’s the one credited with this invention. If you’ve ever wondered exactly how batteries work, read on below to find out more!

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How Does It Work?

Let’s assume you have two alkaline double AA batteries and a flashlight. You know the flashlight needs the batteries to light up, so you open up the battery compartment to put them in. Essentially, what you’ll be doing is adding two critical components to an incomplete circuit. The circuit will still be incomplete until you flick the switch.

Flicking on the switch means you’ve given the double AAs the green light to convert their stored chemical energy into electrical energy. That energy will be transferred from the batteries and into the bulb, thus compelling the device to light up.

Because it’s a circuit, the energy being produced will be moving in a loop. From the batteries to the bulb, and then back to the batteries, using the opposite route.

close up of a person putting batteries into a flashlight
Image By: sockagphoto, Shutterstock

Components Of the Battery

Batteries are often made up of different components, designed to work in tandem to generate the required amount of energy. The first important component to take note of is the battery’s electrodes. They are normally packed with atoms, which are procured from various conducting materials. For example, if you’re working with an alkaline battery, its cathode will be made of manganese dioxide and the anode will be zinc.

The second component is the electrolyte. It’s not only found inside the electrodes, but outside as well. The electrolyte will house the ions, which are supposed to link up with the electrode’s atoms, to trigger a series of electrochemical reactions. As a collective, those reactions are called redox (oxidation-reduction) reactions.

You’ll find different books referring to the battery’s anode as a reducing agent and the cathode as an oxidizing agent. That’s largely due to the fact that the anode is fashioned to lose its electrons to the cathode. We’re describing a reaction that leads to the liberation of electrons from the electrode’s atoms and the simultaneous flow of ions between the two agents.

What usually happens is, the liberated electrons end up congregating inside the reducing agent (anode), leaving the cathode positively charged. This difference in charge eventually creates a force that pulls the electrons toward the charged cathode, to balance everything out. However, regardless of how strong that force is, the electrons cannot get to the cathode without a bridge, as the battery has a separator that acts as an obstacle.

The flashlight’s switch is the bridge. So, when you flick it on, you automatically install a pathway that allows the negative charges to comfortably travel to the other side to meet up with their positive compatriots. But you’ve set a condition whereby they must take the long route, which has the flashlight’s bulb.

Our circuit becomes complete when the current leaves the battery through the bottom part (anode), passes through the bulb, and then re-enters the battery through the cathode, which is at the top.

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What Are the Different Types of Batteries?

Some of the aspects that make batteries different are voltage, size, shape, and capacity (the energy/charge stored). And even though they usually come in various shapes and sizes, ultimately, they fall into one of two categories: primary and secondary batteries.

Primary batteries are non-rechargeable batteries. The kind of batteries that you only get to use once, and that’s it. Secondary batteries, on the other hand, are rechargeable. They can be recharged by passing an electrical current through them, but in the opposite direction. By that we mean, if the current normally flows from point A to B while discharging, recharging will require the current to flow from point B to A.

So, the next time your cell phone runs out of juice, and you decide to plug it in, what you’ll be doing is triggering a chemical reaction inside its batteries, by passing current in reverse.

Primary Batteries

a row of primary batteries
Image By: mohamed abdelghaffar, Pexels

Also known as disposable batteries, primary batteries aren’t outdated or useless—as most people think. Yes, they are not environmentally friendly, and yes, they are less cost-effective. However, compared to secondary batteries, they are more durable and often store much more energy. By the time your disposables run out of charge, you’ll have recharged your secondary batteries at least twice.

Some devices are designed to only use non-rechargeable batteries because they are more practical. A good example is a pacemaker. Seeing as they must be surgically implanted inside a person, they can’t rely on rechargeable batteries.

There are three main types of primary batteries. There’s lithium, alkaline, and zinc-carbon. Since these batteries don’t have any liquid in them, we sometimes refer to them as dry cells.

Advantages of Primary Batteries
  • They have a low initial cost
  • Ideal for single-use applications.
  • Have a relatively higher energy density
  • Are best suited for low-draining applications, such as hearing aids
Disadvantages of Primary Batteries
  • Are non-rechargeable
  • Can’t be recycled
  • Are uneconomical, since you only get to use them once

Button Batteries

coin or button cell batteries
Image Credit: Nor Gal, Shutterstock

These types of batteries are popular among people who rely on hearing aids and those who love quartz watches. Some of them have organic electrolytes and lithium, while others are made of the same material used to manufacture alkaline batteries. Regardless, the battery’s top central section will always act as the negative electrode, and the bottom outer case is the positive electrode.

The positive electrodes will be made of copper oxide, or manganese oxide, while the negatives constitute lithium or zinc. The positive electrodes of button batteries were initially made using mercury oxide, but once we realized how toxic mercury is, its application had to be stopped.

Alkaline Batteries

alkaline batteries
Image Credit: Arcaion, Pixabay

Physically, alkaline and zinc-carbon batteries have the same traits. But when you look at the amount of energy stored inside these batteries, you’ll realize that they pack a heavier punch. They are also comparatively durable and more dependable, which is why they come with a high price tag.

Their negative electrodes are also made using zinc, but the positive ones are purely based on manganese (IV) oxide. Potassium hydroxide acts as the electrolyte in this case.

Zinc-Carbon Batteries

close up of a white remote control with zinc carbon batteries
Image Credit: Paddington, Shutterstock

Of the three, zinc-carbon batteries are the most affordable, conventional, and ideal for simple devices such as flashlights. Their history can be traced back to 1865 when they were invented by Georges Leclanche. He was a French engineer, and to remember him, the cells were dubbed by the engineering community, “the Leclanche Cells.”

Zinc-carbon cells are pocket-friendly but short-lived. They don’t store that much energy, and that’s why their popularity has waned over the years. We call them “zinc-carbon” because the positive and negative electrodes are made using carbon rods and zinc alloy, respectively. You’ll also find ammonium chloride paste in there, as it’s meant to act as the electrolyte.

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Secondary Batteries

lead acid rechargeable batteries
Image Credit: Ocskay Mark, Shutterstock

These cells became popular in the 80s and 90s when the world was slowly starting to warm up to portable devices such as MP3 players and mobile phones. Before that period, their limited capacity made people not like them that much, as they found non-rechargeables more efficient and convenient when operating things like flashlights and toys. During those days, lead-acid accumulators were the most common secondary batteries.

Advantages of Secondary Batteries
  • Have a long shelf life
  • Cost-effective
  • Offer convenience
Disadvantages of Secondary Batteries
  • High initial cost
  • Not easy to dispose of or recycle


mechanic checking a car lead acid battery with multimeter
Image Credit: Smile Fight, Shutterstock

We’ve used the lead-acid battery for more than a century now. It usually has six cells, with electrodes made of lead dioxide and lead metal. The former is the positive terminal, while the latter represents the negative. These batteries use sulfuric acid as the electrolyte. And once the reaction starts, the electrodes are coated with lead sulfate and the acid turns into water.


Nickel-Cadmium batteries bundled together
Image Credit: Sezgin Kipel, Shutterstock

The rechargeable batteries installed in most power tools and toys are nickel-cadmium. They are very durable, and dependable, and must be discharged fully before recharging. Manufacturers have been trying to put an end to the production of these batteries, ever since we realized that their toxic cadmium can easily bond with soil minerals when disposed of in landfills. And if nothing’s done about it, they could eventually find their way into our water sources.


lithium ion battery for electronic devices
Image Credit: Anton Starikov, Shutterstock

Lithium-ion batteries have grown exponentially in popularity these past few years. They are the same batteries used to power MP3 players, tablets, cell phones, laptops, etc. Why is lithium a more favored material in the production of batteries, you ask? It’s because the metal is very light and seamlessly forms ions. The current lithium-ion batteries are also more friendly to our environment, have the ability to store twice the energy stored in nickel-cadmium and operate at relatively high voltages.

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Frequently Asked Questions (FAQs)

How Do You Gauge the Amount of Electrical Energy Stored in a Battery?

Batteries are very similar to boxes. The bigger it is, the more energy it stores. The AA and AAA batteries usually store less electrical energy compared to the C and D-size batteries—even though they are all rated 1.5 volts.

If you’d like to know the exact amount of energy stored inside your battery, look for the measurements written on its side. For the bigger batteries, the measurement will be in watt-hours, while the smaller ones have milliampere-hours.

close up of an alkaline battery
Image Credit: kostkarubika005, Pixabay

Can You Make a Battery Using a Lemon?

Yes, it’s possible to make a battery using a lemon, zinc nail, and copper wire. The lemon juice will act as our electrolyte, while the copper wire and zinc nail take up the positions of the positive and negative electrodes, respectively. If you connect an LED to those two electrodes using a different wire, the electrons will immediately start flowing from zinc to copper, consequently lighting up the bulb in the process.

What’s the Difference Between Battery Voltage and Power?

The voltage, sometimes referred to as the electrical potential, is the force that pushes the battery’s electrons within the cell. How strong that force is will depend on the “potential difference” in the reactions taking place at the electrodes.

If you’d like to determine your battery’s power using its voltage, you’ll first have to figure out the current—which is usually described as the total electrons flowing through a given point of a circuit, at a particular moment. The current multiplied by the voltage equals the battery’s power measurement.

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We have so many types of batteries because a wide variety of materials can be applied as electrodes. They all have varying electrochemical properties, and that’s why the batteries produce different results. The only constant is the fact that they all have positive and negative electrodes, as well as electrolytes.

Featured Image Credit: Ground Picture, Shutterstock


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