BBC Future Planet - Allison Hirschlag
As the world looks to electrify vehicles and store renewable power, one
giant challenge looms: what will happen to all the old lithium batteries?
As the quiet whirr of electric vehicles gradually replaces the revs and noxious
fumes of internal combustion engines, a number of changes are set to filter
through our familiar world.
The overpowering smell of gas stations will fade away into odourless charge
stations where cars can re-juice their batteries as needed. Meanwhile,
gas-powered generator sites that dot the horizon may be retrofitted to house
massive batteries that could one day power entire cities with renewable
energy.
This electrified future is much closer than you might think. General Motors
announced earlier this year that it plans to stop selling gas-powered
vehicles by 2035.
Audi's goal is to stop producing them by 2033, and many other major auto companies are following suit.
In fact,
according to BloombergNEF, two-thirds of the world's passenger vehicle sales will be electric by 2040.
And grid-scale systems the world over are
growing rapidly thanks to advancing battery storage technology.
While this may sound like the ideal path to sustainable power and road travel,
there's one big problem. Currently, lithium (Li) ion batteries are those
typically used in EVs and the megabatteries used to store energy from
renewables, and Li batteries are hard to recycle.
As demand for EVs escalates, as it's projected to, the impetus to recycle
more of them is set to barrel through the battery and motor vehicle
industry
One reason is that the most widely used methods of recycling more traditional
batteries, like lead-acid batteries, don't work well with Li batteries. The
latter are typically larger, heavier, much more complex and even
dangerous if taken apart wrong.
In your average battery recycling plant, battery parts are
shredded down into a powder, and then that powder is either melted
(pyrometallurgy) or dissolved in acid (hydrometallurgy). But Li batteries are
made up of lots of different parts that could explode if they're not
disassembled carefully. And even when Li batteries are broken down this way, the
products aren't easy to reuse.
"The current method of simply shredding everything and trying to purify a
complex mixture results in expensive processes with low value products," says
Andrew Abbott, a physical chemist at the University of Leicester.
As
a result, it
costs more to recycle them than to mine more lithium
to make new ones. Also, since large scale, cheap ways to recycle Li batteries
are lagging behind, only
about 5%
of Li batteries are recycled globally, meaning the majority are simply going to
waste.
But as demand for EVs escalates,
as it's projected to, the
impetus to recycle
more of them is set to barrel through the battery and motor vehicle industry.
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Extracting and processing lithium requires huge amounts of water
and energy, and has been linked to environmental problems near
lithium facilities (Credit: Alamy)
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The current shortcomings in Li battery recycling isn't the only reason they are
an environmental strain. Mining the various metals needed for Li batteries
requires vast resources. It takes
500,000 gallons (2,273,000 litres) of water
to mine one tonne of lithium.
In Chile's Atacama Salt Flats, lithium
mining has been linked to
declining vegetation, hotter daytime temperatures and increasing drought
conditions in national reserve areas. So even though EVs may help reduce carbon dioxide (CO2) emissions over their
lifetime, the battery that powers them starts its life laden with a large
environmental footprint.
We can no longer treat the batteries as disposable
– Shirley
Meng
If the millions upon millions of Li batteries that will give out
after around 10 years or so of use are recycled more efficiently, however, it will help neutralise all that
energy expenditure. Several labs have been working on refining more efficient
recycling methods so that, eventually, a standardised, eco-friendly way to
recycle Li batteries will be ready to meet skyrocketing demand.
"We have to find ways to make it enter what we call a circular lifecycle,
because the lithium and the cobalt and nickel take a lot of electricity and a
lot of effort to be mined and refined and made into the batteries. We can no
longer treat the batteries as disposable," says Shirley Meng, professor in
energy technologies at the University of California, San Diego.
How to recycle Li batteries
A
Li battery cell
has a metal cathode, or positive electrode that collects electrons during the
electrochemical reaction, made of lithium and some mix of elements that
typically include cobalt, nickel, manganese and iron. It also has an anode, or
the electrode that releases electrons to the external circuit, made of graphite,
a separator and an electrolyte of some kind, which is the medium that transports
the electrons between cathode and anode.
The lithium ions travelling
from the anode to the cathode form an electric current. The metals in the
cathode are the most valuable parts of the battery, and these are what chemists
focus on preserving and refurbishing when they dismantle an Li battery.
Meng says to think of an Li battery like a bookshelf with many layers, and the
lithium ions rapidly move across each shelf, cycling back each time to the top
shelf – a process called
intercalation.
After years and years, the bookshelf naturally starts to break down and
collapse. So when chemists like Meng dismantle an Li battery, that's the sort of
degradation they see in the structure and materials.
"We can actually find the mechanisms, [and] either using heat or some kind of
chemical treatment method, we can put the bookshelf back [together]," says Meng.
"So we can let those recycled and refurbished materials go back to the assembly
line to the [Li battery] factories to be made into new batteries."
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Lithium batteries are more internally complex than lead-acid
batteries, composed of many carefully assembled parts
(Credit: Getty Images)
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Improving Li battery recycling and ultimately making their parts reusable will
reinfuse value into the Li batteries already out there. This is why scientists
are advocating for the direct recycling process Meng describes – because it can
give the most precious parts of Li batteries, like the cathode and anode, a
second life. This could significantly offset the energy, waste and costs
associated with manufacturing them.
But disassembling Li batteries is currently being done predominantly by hand in
lab settings, which will need to change if direct recycling is to compete with
more traditional recycling methods. "In the future, there will need to be more
technology in disassembly," says Abbott. "If a battery is assembled using
robots, it is logical that it needs to be disassembled in the same way."
Abbott's team at the Faraday Institution in the UK is investigating the robotic
disassembly of Li batteries as part of the ReLib Project, which specialises in
the recycling and reuse of Li batteries.
The team has also found a
way to achieve direct recycling of the anode and cathode using an
ultrasonic probe, "like what the dentist uses to clean your teeth," he explains. "It focuses
ultrasound on a surface which creates tiny bubbles that implode and blast the
coating off the surface."
This process avoids having to shred the
battery parts, which can make recovering them exceedingly difficult.
According to Abbott's team's research,
this ultrasonic recycling method can process 100 times more material
over the same period than the more traditional
hydrometallurgy
method. He says it can also be done for less than half the cost of creating a
new battery from virgin material.
Abbott believes the process can easily be applied to scale, and used on larger
grid-based batteries, because they typically have the same battery cell
structure, they just contain more cells. However, the team is currently only
applying it to production scrap, from which parts are easier to separate,
because they're already free of their casings.
The team's robotic dismantling tests are ramping up though.
"We have a demonstrator unit that currently works on whole electrodes and we
hope in the next 18 months to be able to showcase an automated process working
in a production facility," says Abbott.
Degradable batteries
Some scientists are advocating for a move away from Li batteries in favour of
ones that can be produced and broken down in more eco-friendly ways. Jodie
Lutkenhaus, a professor of chemical engineering at Texas A&M University, has
been working on a battery that is made of organic substances that can degrade on
command.
"Many batteries today are not recycled because of the associated energy and
labour cost," says Lutkenhaus. "Batteries that degrade on command may simplify
or lower the barrier to recycling. Eventually, these degradation products could
be reconstituted back into a fresh new battery, closing the materials life-cycle
loop."
It's a fair argument considering that, even when a Li battery is dismantled and
its parts are refurbished, there will still be some parts that can't be saved
and become waste. A degradable battery like the one
Lutkenhaus' team is working on
could be a more sustainable power source.
Organic Radical Batteries (ORBs)
have been around since the 2000s, and function with the help of organic
materials that are synthesised to store and release electrons. "An Organic
Radical Battery has two of these [materials], both acting as electrodes, that
work in concert to store and release electrons, or energy, together," explains
Lutkenhaus.
The team uses an acid to break their ORBs down into amino acids and other
byproducts, however, conditions need to be just right for the parts to degrade
properly. "Eventually we found that acid at elevated heat worked," says
Lutkenhaus.
There are a number of challenges ahead for this degradable battery though. The
materials needed to create it are expensive, and it has yet to provide the
amount of power required for high-demand applications like EVs and power grids.
But perhaps the greatest challenge degradable batteries like Lutkenhaus's face
is competing with the already well-established Li battery.
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As demand for electric vehicles surges in the coming decades, the
need for a way to recycle their batteries will grow too
(Credit: Getty Images)
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The next step for scientists pushing direct recycling of Li batteries forward is
working with battery manufacturers and recycling plants to streamline the
process from build to breakdown.
"We are really encouraging all the battery cell manufacturers to barcode all the
batteries so with robotic AI techniques we can easily sort out the batteries,"
says Meng. "It takes the entire field to cooperate with each other in order to
make that happen."
Li batteries are used to power many different devices, from laptops to cars to
power grids, and the chemical makeup differs depending on the purpose, sometimes
significantly. This should be reflected in the way they're recycled. Scientists
say battery recycling plants must separate the various Li batteries into
separate streams, similar to how different types of plastic are sorted when
recycled, in order for the process to be most efficient.
And even though they face an uphill battle, more sustainable batteries are
slowly but surely coming onto the scene. "We can already see designs entering
the market which make assembly and disassembly easier, and it is probable that
this will be an important topic in future battery development," says Abbott.
On the production side, battery and car manufacturers are
working on cutting down
on the materials needed to build Li batteries to help reduce energy expenditure
during mining and the waste each battery creates at the end of its life.
Electric car manufacturers have also begun to reuse and repurpose their own
batteries in a number of different ways. For example, Nissan is
refurbishing old Leaf car batteries
and putting them in automated guided vehicles that bring parts to its factories.
Speed bumps ahead
The steadily increasing market
demand for EVs already has companies across the automobile industry spending
billions of dollars on increasing the sustainability of Li batteries. However,
China is currently the
largest producer of Li batteries
by far, and subsequently
ahead when it comes to recycling them.
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So far, China produces the most lithium batteries, and it also has
more capability to recycle them than other producers
(Credit: Getty Images)
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Widely adopting standardised methods for recycling Li batteries that include
sorting streams for the different types will get them a big step closer.
Meanwhile, using AI technology to refurbish the most useful parts, such as the
cathode, could help countries with small supplies of Li battery components to
not have to rely so much on China.
Developing
new batteries that might rival the Li battery
will also likely shake up the industry by creating some healthy competition. "I
do think it does the world better if we diversify the portfolio for battery
storage, particularly for grid storage," says Meng.
The advent of a less complex, safer battery that is cheaper to make and easier
to separate at the end of its life is the ultimate answer to the current
sustainability problem with EVs. But until such a battery makes an appearance,
standardising Li battery recycling is a significant move in the right direction.
And in about 2025, when millions of EV batteries reach the end of their initial
life cycles, a streamlined recycling process will look much more appealing to
economies the world over. So perhaps, by the time EVs become the predominant
form of transport, there will be a good chance their batteries will be gearing
up for a second life.
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