This video was created in partnership with Bill Gates, inspired by his new book
“How to Avoid a Climate Disaster.” You can find out more about how we can all work together
to avoid a climate disaster in the link below.
[♩INTRO]
Renewable energy is the future. The cost just keeps going down, and for
lots of countries, the goal is to transition to as much renewable energy as possible.
But for some of the more popular options, like solar and wind power, there’s a problem:
the supply is inconsistent. Maybe it’s cloudy for a few days,
or there’s not much wind for a while. But people still need electricity.
The solution might seem obvious — just build batteries and save extra power for when you need it.
But it’s not that simple, because battery technology hasn’t come far enough.
You can try building enormous arrays of them,
but at a certain point, it’s just too expensive. And it turns out, there are some very good
reasons why making improvements is hard. But scientists are on it.
Also, quick aside: It might seem like new laptops and phones have better battery life
every year, but that’s mostly from improvements to the rest of the device.
They allow manufacturers to cram in bigger batteries and
better processors that draw less power. Some of the best battery tech we have is
what’s known as lithium-ion. It’s what’s in your phone, your laptop — maybe even your electric car.
These batteries have three main parts:
Two sides that store electric charge, and an electrolyte separator between them.
One side is the cathode, usually made of a chemical compound called a lithium
metal oxide. The compound is a combination of lithium, oxygen, and some metals — like cobalt.
The other side is the anode, and it’s most often made of sheets of crystalline carbon, a.k.a.
graphite. The same stuff that’s in pencils. And finally, separating these two sides is the
electrolyte. This is a material that’s designed to allow positively-charged lithium ions to pass
through, but not negatively-charged electrons. When you charge a battery, lithium ions from
the cathode are released and travel through the separator,
where they’re stored in the graphite anode. Then, when you use the battery to power
something, the opposite happens: The lithium ions are released by the
anode and pass through to the cathode. Ultimately, this creates an imbalance where
there’s more negative charge in the anode and more positive charge in the cathode.
To balance things out, the electrons in the anode travel to rejoin their lithium
friends in the cathode. But since they can’t pass through the separator, they take the only route
available — through the device you’re powering.
In general, the more ions you can fit in a battery,
the more energy it will be able to store. And part of why lithium-ion batteries are so
popular is that lithium ions are very small, even for ions. So you can store more of them
without increasing the battery’s size and weight. In other words, they have a high energy density.
And researchers have been working to increase it even more, so that we can
use batteries for bigger projects — like power storage, and also bigger electric vehicles.
But that’s not simple.
For instance, one way to increase the energy density of a battery
would be to have an anode that can store more lithium ions when the battery is charged.
And there are materials like that! Like, silicon can hold more lithium ions than
graphite. But because of the way it’s structured, those extra ions also make it expand.
The expansion cracks through a protective layer
around the anode, and the battery loses a bit of its silicon — and its capacity — the next time you
charge it. So the battery doesn’t last as long.
Another main way researchers are trying to increase energy density is by improving
the cathode. But that’s equally tricky. Two main things you need from a good cathode
are a high energy density, and also a high conductivity.
In other words, you need a bunch of ions, but they also need to
move fast to generate that current. Unfortunately, many cathode materials
with high energy density and high conductivity tend to be less stable and less safe. They also
tend to be less sustainable, because they often use metals that are less abundant on Earth.
So like with anodes, a lot of research has focused on energy density.
One way to improve the cathodes here might be to use a metal oxide with more nickel in it,
and less of the harder-to-find cobalt. Because of the way nickel ions are structured,
they can lose more electrons than some of the other metals used in cathodes,
giving the battery a higher energy density. Problem is… this super-charged nickel isn’t
exactly stable. So it tends to react with other parts of the battery,
messing with its structure and again, destroying the battery’s capacity over time.
Now, researchers are working on ways to prevent this — and on ways to improve
anodes. So there is hope for the future! Progress has just been slow, and we’re not
quite at the point where it’s practical to build huge battery arrays to support
all our solar and wind power. We’re getting closer, though. And to
supplement this research, other scientists are also looking into other types of batteries that
rely on different kinds of chemistry and physics. Because in the end, improving batteries is a
tough problem. But it’s also an important one — because in many ways, the future of our planet
also depends on the future of batteries. Really, though, many of the solutions to climate
change are complicated. It’s a big problem with a lot of pieces — but it’s not a hopeless one.
If you want to learn more about how we could actually get to a world with net-zero greenhouse
gas emissions, you might like Bill Gates’s new book, “How to Avoid a Climate Disaster.”
It talks about batteries, but also about how we feed ourselves, how we heat and cool our
buildings, how we get around, and more — and how we could do those things more responsibly,
from an individual to a government level. You can find out more about how we can all
work together to avoid a climate disaster in the link below.
[♩OUTRO]