Researchers recently and quite accidentally discovered something that could change the
whole electric car ballgame.
If their predictions are accurate, we could one day live in a world where cars can be
fully charged in minutes instead of hours, and their power storage units would last decades
instead of years.
What is this tantalizing breakthrough you ask?
A monumental leap forward in capacitor technology.
Many of the current drawbacks of electric cars stem from how batteries work.
Batteries rely on chemical reactions, which means for a lithium-ion battery to release
energy you have to wait for the lithium to shuffle through an electrolyte, and when you
want to store energy you have to wait for the lithium to shuffle back.
Lithium-ion batteries also degrade, and replacing one in an electric car would be enormously
expensive.
In contrast capacitors store static electricity, like what builds up on a balloon as you rub
it on your hair.
Capacitors can be as simple as two metal plates separated by air.
When a current is applied to the plates, a positive charge builds up on one plate and
a negative charge builds up on the other.
No electrolytes, no shuffling ions, just electrons on a plate waiting to pounce like a caged
lion.
As a result capacitor can be fully charged almost instantly, and since they can also
deliver energy quickly, that means capacitors can provide more power than batteries.
They are much more durable than lithium-ion batteries too, lasting through tons of charge
and discharge cycles with little degradation.
There is an achilles heel: they just can’t hold very much energy.
There are tricks to squeeze more charge onto the plates, like increasing their surface
area and reducing the distance between them by swapping out the air with a thin insulator.
Do that and you’ve created a supercapacitor, but even then, the best supercapacitors today
hold just 10 watt-hours per kilogram, about 5% of the energy of a lithium ion battery
of the same weight.
You would need a capacitor the size of a bus to get any real use out of it.
As it happens in 2010 Shanghai experimented with electric buses powered by capacitors
that charged up every couple of stops.
That’s a pretty clever use for them, but if you want a personal car smaller than a
bus that can travel more than five miles without stopping, capacitors are going to have to
step up their game.
Bizarrely the big breakthrough in supercapacitor technology may come from… contact lenses?
Soft contacts use a polymer mesh that can swell up and store water.
One of the original inventors has been tinkering with the polymer ever since, and found that
adding different elements imbues it with different properties, like the ability to store electricity.
Actually they were shocked at just how much energy the polymer could store.
A 2016 test of the little blue material found it stored 100 times the energy the researchers
expected.
Since then they’ve been testing the material to see if it works in real world conditions,
and after 14 months of research have concluded that the material could eventually store 180
watt-hours per kilogram, putting it almost on par with battery energy density, at least
by weight.
The supercapacitors could be quite a bit more voluminous, perhaps 30% bigger than an equivalent
battery.
Still, they’d be faster to charge, cheaper to make, and wouldn’t have the risk of catching
fire since they’d be mostly water.
They could also have applications outside of cars, like storing energy for when it’s
in high demand, or when renewable sources aren’t generating electricity.
For now regular old chemical batteries are still the best fit for electric cars.
But if this is the breakthrough the researchers believe it is, batteries could be on their
way out in the next decade.
In a weird way, soft contact lenses may help us see a brighter future.
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Just because capacitors are improving doesn’t mean we’re not developing new and better
batteries too.
Like a squishy battery!
You can learn more about that here!
None other than Elon Musk himself has said that supercapacitors are the future of electric
cars.
But he also thought a tiny submarine would help… so ya know,
grain of salt and all that.
Thanks for watching and I’ll see you next time on Seeker.