How Supercapacitors Could Make Batteries a Thing of the Past


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. If you like what you see don’t forget to
subscribe. 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.