New battery takes less than 5 minutes to fully charge

[This is a transcript with links to references.]

Electric vehicles are great, but let’s be honest, it’s more convenient to fill up a fuel tank with gasoline than sit around and wait until the battery is full. It takes so long that sometimes you even have to talk to other people at the charging place, uh. Well, this new battery from researchers at Cornell might solve the problem. Let’s have a look.

Lithium batteries or any batteries really have two poles, plus and minus, called the anode and cathode. When you use the battery, negatively charged ions will move from the minus to the plus side through a substrate called an electrolyte. This movement of charges creates a current that powers your device. When you recharge the battery, these particles have to move back from the plus to the minus side, so that you can use it again.

So the battery has these three main ingredients: the anode the cathode and the electrolyte. And since all good things come in threes, for a good battery you need a mix of materials with three properties.

First, you need something that can reliably and durably store charges, that is the battery needs a Low Self-Discharge Rate.  It must also be possible to repeat the process of using and recharging the battery repeatedly, that is you want a Long Life-Cycle.  And third, you also want something that can store a lot of charge in a small place that is a high energy density. Lithium ion batteries score high on all three counts, which is why they have become so widely used.

In a lithium-ion battery, the cathode contains lithium, hence the name. The anode is usually graphite, though there is some variety in materials. Currently the fastest charging lithium batteries for electric vehicles can go from 20% to 80% in about 15-20 minutes. However, these extra fast charging batteries are more expensive than the usual ones, which take two or three times as long.

Of course, it’s not just electric vehicles, but pretty much any other mobile device is now powered by lithium batteries, phones, tables, cameras. My new phone that’s a Samsung S24, takes about 60 to 90 minutes to fully charge. No, it’s not the ultra-version. Does anyone really need a Terabyte of storage. Do you. For what?

The new researcher now comes from Cornell university and was just published. It’s an experimental work in which they test a new type of battery. They used a combination of lithium and indium in the battery anode. Usually, the anode is made of graphite.

Indium is element 49 of the periodic table, it is a metal and the reason it’s called indium is because it has a spectral line that is indigo blue. It has two important properties that made the researchers think it would be good for the task.

First, indium has what’s called a low migration energy barrier. This isn’t a political statement about economic refugees, it means that the ions have a small energy barrier to overcome when one charges the battery. Basically, they move easily.

And second, indium has a small exchange current density, which means it can store energy for a long time. In their tests the researchers were able to charge the battery in about 2 minutes and showed stability in over 1,000 cycles.

Now this sounds quite promising but there are a lot of ifs and buts. First of all they quote an energy density of 145 Watt hours per kilogram, which isn’t bad but about half that of current lithium ion batteries. Then there’s the question how robust such a battery is and how well it copes with different temperatures. There is also the issue that indium is at the moment mostly produced as a by-product of zinc mining. It would probably be difficult to rapidly increase its supply because there’s very little direct production.

And then there is the question whether it even matters how fast the thing charges. Because I believe what people with have “range anxiety” are worried about is not so much that it’ll take a long time to charge an electric vehicle. It’s that they must stop and charge it to begin with.

If I had a choice between a lithium-ion battery that takes an hour to change and one that’s twice as large but charges in 5 minutes, I’d stick with the lithium battery. I can’t really think of any situation where I need to charge a phone in 5 minutes. What do you think? Let me know in the comments.