The Drones are Coming! - part 7 of 1 2 3 4 5 6 7

by Mike McNamee Published 01/02/2017

Why Lithium?

Lithium has been mentioned frequently in this feature and has recently acquired some notoriety with the spectacular failures associated with the Samsung Galaxy 7 and even more recently with the withdrawal of the GoPro Karma drone because of catastrophic battery failures. So here is why lithium is so good as a battery component, despite some of the issues that come with it.

Without wishing to bring any chemophobics out in a rash, we have to take you back to your school chemistry days and the Periodic Table.

One of the most elegant and profound pieces of infographics, Dmitri Mendeleev's table sets out the chemical elements in rising order of atomic number and then grouped vertically into 'like-minded' elements (ie of the same generic chemical properties). Thus the highly reactive metallic elements of lithium (Li), sodium (Na), and potassium (K) occupy the left-most Group 1 and, for example, the highly reactive halide gases fluorine (F), chlorine (Cl), bromine (Br) and iodine (I) occupy Group VIIA on the right-hand side of the table. As a general rule the higher up the table the element is placed, the higher its reactivity and so if you pick combinations of battery materials from opposite sides of the table and from high up the table you get the most vigorous reactions. By way of example if you mix molten sodium (high left in the table) with molten sulphur (high-right in the table) you get the mother of all explosions (trust me, I have done it!).

Although there are other complicating factors this, in essence, is what makes lithium the king of all electrode materials. It is high left in the table making it light and highly reactive and is also abundant generally the more abundant materials in the Earth's crust are lighter, a result of the early nuclear chemistry of the Big Bang when the universe was created. The only problem with lithium, as Samsung have found to their cost is keeping it under control the more powerful the reactants in a battery, the bigger the drama when things go wrong.

Lithium has been combined with at least 10 different other electrode materials to make operating batteries. For example, lithium and iodine are used in human pacemaker batteries; lithium combined with thionyl chloride is used for spectacularly powerful military batteries; lithium combined with sulphur (usually as sulphur dioxide) as first made in the 60s and is about to re-emerge with the latest graphene battery technology.

Overall then, this is a simplified look at why lithium is the king of electrode materials.

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1st Published 01/02/2017
last update 01/08/2018 14:48:24

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