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3.7 V lithium-ion battery

3.7 V lithium-ion battery (AlexLMX, iStockphoto)

STEM in Context

How does a lithium-Ion battery work?

Becky Chapman

Summary

Learn about the electrochemistry in the batteries that power many of the devices you use every day.

Picture a world without lithium-ion batteries (often called Li-ion batteries or LIBs). Need help? Mobile devices wouldn’t look the way they do now. 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 1980s. Scary, isn't it?

Did you know?

Lithium-ion batteries were first manufactured and produced by SONY in 1991.

Lithium-ion batteries have become a huge part of our mobile culture. They provide power to much of the technology that our society uses.

What are the parts of a lithium-ion battery?

A battery is made up of several individual cells that are connected to one another. Each cell contains three main parts: a positive electrode (a cathode), a negative electrode (an anode) and a liquid electrolyte.

Parts of a lithium-ion battery
Parts of a lithium-ion battery (© 2019 Let’s Talk Science based on an image by ser_igor via iStockphoto).

Just like alkaline dry cell batteries, such as the ones used in clocks and TV remote controls, lithium-ion batteries provide power through the movement of ions. Lithium is extremely reactive in its elemental form. That’s why lithium-ion batteries don’t use elemental lithium. Instead, lithium-ion batteries typically contain a lithium-metal oxide, such as lithium-cobalt oxide (LiCoO2). This supplies the lithium-ions. Lithium-metal oxides are used in the cathode and lithium-carbon compounds are used in the anode. These materials are used because they allow for intercalation. Intercalation means that the molecules are able to insert something into them. In this case, the electrodes are able to have lithium-ions move easily in and out of their structures.

What is the chemistry involved in lithium-ion batteries?

Inside a lithium-ion battery, oxidation-reduction (Redox) reactions take place.

Reduction takes place at the cathode. There, cobalt oxide combines with lithium ions to form lithium-cobalt oxide (LiCoO2). The half-reaction is:

CoO2 + Li+ + e- → LiCoO2

Oxidation takes place at the anode. There, the graphite intercalation compound LiC6 forms graphite (C6) and lithium ions. The half-reaction is:

LiC6 → C6 + Li+ + e-

Here is the full reaction (left to right = discharging, right to left = charging):

LiC6 + CoO2 ⇄ C6 + LiCoO2

How does recharging a lithium-ion battery work?

When the lithium-ion battery in your mobile phone is powering it, positively charged lithium ions (Li+) move from the negative anode to the positive cathode. They do this by moving through the electrolyte until they reach the positive electrode. There, they are deposited. The electrons, on the other hand, move from the anode to the cathode.

What happens in a lithium-ion battery when discharging
What happens in a lithium-ion battery when discharging (© 2019 Let’s Talk Science based on an image by ser_igor via iStockphoto).

 

Illustration – Text Version

When the battery is in use, the lithium ions flow from the anode to the cathode, and the electrons move from the cathode to the anode.

 

When you charge a lithium-ion battery, the exact opposite process happens. The lithium ions move back from the cathode to the anode. The electrons move from the anode to the cathode.

What happens in a lithium-ion battery when charging
What happens in a lithium-ion battery when charging (© 2019 Let’s Talk Science based on an image by ser_igor via iStockphoto).

 

Illustration - Text Version

When the battery is charging, the lithium ions flow from the cathode to the anode, and the electrons move from the anode to the cathode.

 

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.

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.

What makes lithium-ion batteries good for mobile technologies?

It’s simple. lithium-ion batteries have the highest charge density of any comparable system. This means they can give you a ton of energy without being very heavy.

This is for two reasons. First, lithium is the most electropositive element. Electropositivity is a measure of how easily an element can donate electrons to produce positive ions. In other words, it’s a measure of how easily an element can produce energy. Lithium loses electrons very easily. This means it can easily produce a lot of energy.

Lithium is also the lightest of all metals. As you’ve learned, intercalation materials are used as electrodes in lithium-ion batteries instead of actual lithium metal. Still, these batteries weigh much less than other types of batteries that use metals like lead or nickel.

Are there any risks with using lithium-ion batteries?

While these batteries are pretty impressive, they do have their downsides. The biggest complaint is that they wear out fairly quickly whether you use them or not. A typical lithium-ion battery will last about 2-3 years before it has to be replaced. That can get expensive! The production and disposal of lithium-ion batteries also has a big impact on the environment, so the longer those batteries can last the better.

As you learned, lithium is extremely reactive. When manufacturers make lithium-ion batteries, they have to take certain precautions so that the batteries are safe to use. However, you may have heard of some electronics, such as laptops or cell phones, 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. For safety reasons, lithium-ion batteries include a separator. This prevents the electrodes of the battery’s cells from touching each other. But if this separator gets ripped or damaged, the electrodes can touch. This can cause a huge build-up of heat. If this build-up of heat produces a spark, the highly flammable electrolyte can catch on fire.

Once there are flames in one cell, they can quickly spread to others. And before you know it, your laptop is a pool of melted plastic. A build-up of heat can also cause the pressure in your laptop to rise very quickly and BOOM!

Watch what happens when a lithium-ion battery is short circuited (1:13 min.).

 

However, you don’t need to worry too much. These events are very rare. In fact, lithium-ion batteries are actually very safe. Also, right now there is a lot of research going into improving every part of these batteries. For example, researchers have created a liquid electrolyte than turns into a solid when it is hit. This will help keep batteries from heating up or catching on fire if they are damaged! Soon, lithium-ion batteries will likely be even safer, last longer, and cost even less.

Did you know?

Most electric cars run on lithium-ion batteries. We are starting to see more and more cars that plug-in instead of having to fill up on gasoline! 
 

 

Starting Points

Connecting and Relating
  • Has anyone you know had an accident with lithium-ion batteries? What happened?
  • Do you have a device with a lithium-ion battery? Have you had to replace the battery because it wore out?
  • If a safer alternative to lithium-ion batteries was developed but it was more expensive, would you be willing to pay more?
Connecting and Relating
  • Has anyone you know had an accident with lithium-ion batteries? What happened?
  • Do you have a device with a lithium-ion battery? Have you had to replace the battery because it wore out?
  • If a safer alternative to lithium-ion batteries was developed but it was more expensive, would you be willing to pay more?
Relating Science and Technology to Society and the Environment
  • lithium-ion batteries have become the norm for most electronic devices, yet problems still persist, especially with regard to safety. Should manufacturers be forced to accept liability for any accidents that occur with the devices they produce, or should people be expected to ‘use at their own risk’?
Relating Science and Technology to Society and the Environment
  • lithium-ion batteries have become the norm for most electronic devices, yet problems still persist, especially with regard to safety. Should manufacturers be forced to accept liability for any accidents that occur with the devices they produce, or should people be expected to ‘use at their own risk’?
Exploring Concepts
  • Why is lithium a good choice for a rechargeable battery?
  • In which direction do lithium ions move when the battery is in use? In which direction do lithium ions move when the battery is recharging?
  • What is the role of the electrolyte?
  • lithium-ion batteries are ‘rechargeable,’ as are the lead storage batteries found in your car. Compare how they work.
Exploring Concepts
  • Why is lithium a good choice for a rechargeable battery?
  • In which direction do lithium ions move when the battery is in use? In which direction do lithium ions move when the battery is recharging?
  • What is the role of the electrolyte?
  • lithium-ion batteries are ‘rechargeable,’ as are the lead storage batteries found in your car. Compare how they work.
Media Literacy
  • Have you ever thought about the amount of battery power that is used in medical devices? (e.g., external defibrillator, hearing aids, surgical power tool, glucose monitor, or infusion pump.) Search media articles for any reports on lithium-ion battery failure in these devices. What are some of the big issues surrounding battery failure in medical devices?
Media Literacy
  • Have you ever thought about the amount of battery power that is used in medical devices? (e.g., external defibrillator, hearing aids, surgical power tool, glucose monitor, or infusion pump.) Search media articles for any reports on lithium-ion battery failure in these devices. What are some of the big issues surrounding battery failure in medical devices?
Teaching Suggestions
  • This article can be used for Chemistry and Engineering & Technology teaching and learning related to electrochemistry and energy storage. Concepts introduced include lithium-ion batteries, cell, electrode, electrolyte, rechargeable, group (Periodic Table), intercalation materials, charge density, electropositive, separator and flammable.
  • Before reading this article, teachers could have students complete an Admit Slip. Download ready-to-use reproducibles using the Admit Slip learning strategy for this article in [Google doc] and [PDF] formats.
  • After reading the article, teachers could have students compare the positive and negative aspects of lithium-ion batteries using a Pros & Cons Organizer. Ready-to-use Pros & Cons Organizer learning strategy reproducibles are available in [Google doc] and [PDF] formats. 
  • To learn more, teachers could have students conduct research on the history and development of rechargeable batteries. Using a BYO (Build Your Own) Timeline learning strategy, students could create a timeline that highlights the major innovations and their significance over time. A ready-to-use BYO Timeline Planning Support Form for this strategy is available in [Google doc] and [PDF] formats. 
Teaching Suggestions
  • This article can be used for Chemistry and Engineering & Technology teaching and learning related to electrochemistry and energy storage. Concepts introduced include lithium-ion batteries, cell, electrode, electrolyte, rechargeable, group (Periodic Table), intercalation materials, charge density, electropositive, separator and flammable.
  • Before reading this article, teachers could have students complete an Admit Slip. Download ready-to-use reproducibles using the Admit Slip learning strategy for this article in [Google doc] and [PDF] formats.
  • After reading the article, teachers could have students compare the positive and negative aspects of lithium-ion batteries using a Pros & Cons Organizer. Ready-to-use Pros & Cons Organizer learning strategy reproducibles are available in [Google doc] and [PDF] formats. 
  • To learn more, teachers could have students conduct research on the history and development of rechargeable batteries. Using a BYO (Build Your Own) Timeline learning strategy, students could create a timeline that highlights the major innovations and their significance over time. A ready-to-use BYO Timeline Planning Support Form for this strategy is available in [Google doc] and [PDF] formats. 

Learn more

How Batteries Work (2015)
Adam Jacobson: TED-Ed (4:19 min.) Brief video explaining the history of batteries, how they work, and the future of battery development.

A Silicon Valley startup is giving lithium-ion batteries a much-needed silicon boost (2018)
Article by Akshat Rathi outlines new development in lithium-ion battery technology: the addition of silicon to the batteries.

Will there be enough EV Battery Material? (2018)
Now You Know video (5:10 min.) discussing the materials used in EV (electric vehicle) batteries and the mathematics behind electric vehicle adoption.

References

Alarco, J., & Talbot, P. (2015, April 30). The history and development of batteries. Phys.org.

Dell, R. M., & Rand, D. A. (2001). Understanding Batteries. RSC Paperbacks.

Hordé. T., Achard, P., & Metkemeijer, R. (2012). Schematic of the working principle of a Li-ion battery. HAL archives-ouvertes.fr & ResearchGate.

Tarascon, J. M., & Armand, M. (2001). Issues and challenges facing rechargeable lithium batteries. Nature, 414(6861), 359-367. DOI:10.1038/35104644

Treptow, R. S. (2003). Lithium Batteries: A Practical Application of Chemical Principles. Journal of Chemical Education, 80(9), 1015. DOI:10.1021/ed080p1015

Wilson, Tracy V. (n.d.) What Causes Laptop Batteries to Overheat? HowStuffWorks.

Woodford, C. (2018, August 3). Lithium-ion batteries. Explain that Stuff.

Becky Chapman

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”.