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Picture a world without lithium ion (Li-ion) batteries. Need help? OK: picture no mobile devices. And picture huge, heavy cell phones and laptops. Also picture that both of these things are so expensive that only very rich people can afford them. What you are picturing is the 1980’s. Scary, isn't it?

Did you know? Lithium ion batteries were first introduced by SONY way back in 1991.

Lithium ion batteries have become a huge part of our mobile culture. They fuel much of the technology our society uses. So, how do they work?

Lithium Batteries: They Just Keep on Going and Going!

A battery is made up of several individual cells. These cells are connected to provide the battery’s desired power. Each cell contains three main parts: a positive electrode, a negative electrode and a liquid electrolyte.

When an external power source, like a USB port, is supplied, positively charged lithium ions (Li+) move from the positive electrode to the negative electrode. They do this by 'swimming' through the electrolyte until they reach the negative electrode, where they are deposited.

Did you know? Sometimes lithium ion batteries are referred to as "rocking chair batteries." This is because lithium ions 'rock' back and forth between the electrodes.

When you charge a battery, the exact opposite process happens. The lithium ions swim back from the negative electrode to the positive electrode. This process supplies electrical energy. Every time a lithium ion leaves or enters an electrode, an electron moves with it.

As long as lithium ions are making the trek from one electrode to another, there is a constant flow of electrons. This provides the energy to keep your device running. Since this cycle can be repeated hundreds of times, this type of battery is rechargeable.

Remember where lithium is in the periodic table? It’s in the first column. That means it’s super-reactive. It's just itching to get rid of an electron. So for safety reasons, intercalation materials are used as the electrodes in commercial batteries. These materials have large spaces in their structures so that lithium ions can freely move in and out.

Batteries On The Move!

So what makes Li-ion batteries good for mobile technology? It’s simple: these batteries have the highest charge density of any comparable system. In simple terms, this means they can give you a ton of energy without being very heavy.

This happens because of two reasons. First, lithium is the most electropositive element. This means it loses electrons very easily. This is a measure of the energy in can produce. It is also the lightest of all metals. Even though intercalation materials are used as electrodes, Li-ion batteries still weigh much less than other types of batteries that use metals like lead or nickel.

Did you know? The name "lithium ION" battery is meant to emphasise that these batteries contain no lithium metal.

While these batteries are pretty impressive, they do have their problems. The biggest complaint is that they degrade fairly quickly whether you use them or not. A typical battery will last about 2-3 years before it has to be replaced. That gets expensive!

The other problem with these batteries is their reactivity. You may have heard about some laptops bursting into flames because of their batteries. While this might be a good excuse for not handing in your English essay on time, it’s a pretty dangerous situation. So for safety reasons, there is a separator to keep the electrodes from touching each other. But if it gets ripped or punctured and the electrodes touch, there can be in a spark or a huge buildup of heat. A spark will ignite the highly flammable electrolyte. Once there are flames in one cell, they quickly spread to others. And before you know it, your laptop is a pool of melted plastic. Also, a buildup of heat will cause the pressure to rise very quickly and BOOM! (If you want a visual, think the result of too much air in a balloon!)

However, you don’t need to worry too much. These events are very rare. In fact, lithium ion batteries are actually very safe. Besides, right now there is a lot of research going into improving every part of these batteries. Soon, they'll likely be even safer, last even longer and cost even less.

This article was updated by Let's Talk Science staff on 2017-02-14 to improve readability by reducing the reading grade level.

Learn More!

For more information about your new favourite batteries visit:

How Stuff Works:

"How Lithium-Ion Batteries Work" Click Here.

"What is causing lithium-ion laptop batteries to overheat or catch fire? Is my battery at risk?" Click Here.

Battery University.

Tarascon, J.-M.;.Armand, Nature. 2001, 414, 359-367

Treptow, Richard S. J. Chem. Educ. 2003, 80, 1015-1020

Dell, R.M.; Rand, D.A.J Understanding Batteries, Royal Society of Chemistry: Cambridge, 2001.


Becky Chapman is a graduate student in the Department of Chemistry at the University of Ottawa. Her research is in the physical chemistry field, which although people often think is scary, in her opinion, is actually tons of fun. Fun fact about Becky? Back home, she had a cat named “Big Head” (Ed for short) who replaced her family’s first cat who lived to be 15 and was appropriately named “Cat”.


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