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03.1 What is a lithium-ion battery?

Lithium-ion batteries power electric vehicles (& lots of other items we use daily)

Lithium-ion batteries power our world & are being increasingly used to decarbonise our lives, transport & energy storage.

A lithium-ion battery is a rechargeable battery cell, containing the following parts:

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Depending on the application, lithium-ion batteries come in a range of form types. A cylindrical cell may be used in an electric power tool, a pouch cell in your mobile phone, a prismatic cell in a battery storage system & blade cell in an electric car.

All form types are used in electric vehicles.

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How do lithium ion battery cells work?

Like all batteries, lithium ion battery cells contain two electrodes; the cathode (positive) & anode (negative). The anode is made from carbon, primarily graphite, & the cathode from metal oxides, including lithium.

Lithium ions move between the electrodes through an electrolyte, creating an electric current through the conversion of chemical energy to electrical energy. A very thin porous separator sits between the cathode & anode.

They can be repeatedly charged and discharged through many hundreds or thousands of cycles, and are 'energy dense', meaning they can hold an 'enormous amount of power in a very small space' (thanks to our friend Professor Paul Christensen for that quote!). This makes them perfect for use in a huge range of applications &, to quote Professor Paul again, 'you're never more than four feet away from a lithium-ion battery'.

Later, we look at thermal runaway, which may happen due to a short circuit in a battery cell & is how electric vehicle lithium-ion traction battery fires start.

What's the difference between a lithium-ion battery & a lithium battery?

There's some confusion online about lithium-ION batteries vs lithium batteries, especially around whether water can be used on a lithium-ion battery to extinguish a fire. So what's the difference?

Lithium-ION battery: Rechargeable, known as a secondary battery. Does not contain lithium metal, just lithium in ionic form, therefore is perfectly safe to use water.

Lithium battery: Not rechargeable, single use only, known as a primary battery. Contains lithium metal which can react violently upon contact with water.

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