Tech Briefs Magazine - June 2024 - 32

" The typical thickness of the battery
electrode is only about 50 microns to
100 microns but now, in this work, we are
talking about 300 microns, 500 microns.
That is five times higher than the proportion
of mass of the electrode in a real
battery device. "
Using the researchers' newly designed
thicker electrodes with fast
charge transport capability would increase
the percentage of active components
and enhance the energy capacity
normalized by the total weight of the
battery package, Sun said. They also
make the batteries compact due to the
high density of the electrodes, which
enables packing more electrode active
materials within the same space.
For more information, contact Jamie
Oberdick at jco11@psu.edu; 814-8650285.
An
Efficient and Cost-Effective Solution for Battery Recycling
The one-solution system can cover the functions of both leaching and recovery of critical metals.
Oak Ridge National Laboratory, Oak Ridge, TN
U
sed lithium-ion batteries from cell
phones, laptops, and a growing
number of electric vehicles are piling
up, but options for recycling them remain
limited mostly to burning or
chemically dissolving shredded batteries.
The current state of the art methods
can pose environmental challenges
and be difficult to make economical
at the industrial scale.
The conventional process recovers few
of the battery materials and relies on
caustic, inorganic acids and hazardous
chemicals that may introduce impurities.
It also requires complicated separation
and precipitation to recover the critical
metals. However, recovering metals
such as cobalt and lithium could reduce
both pollution and reliance on foreign
sources and choked supply chains.
Researchers at the Department of Energy's
Oak Ridge National Laboratory
have improved on approaches that dissolve
the battery in a liquid solution in
order to reduce the amount of hazardous
chemicals used in the process.
This simple, efficient, and environmentally
friendly solution developed
by ORNL researchers overcomes the
main obstacles presented by previous
approaches.
The spent battery is soaked in a solution
of organic citric acid - which occurs
naturally in citrus fruits - dissolved
in ethylene glycol, an antifreeze
agent commonly used in consumer
products like paint and makeup. Citric
acid comes from sustainable sources
and is much safer to handle than inorganic
acids. This green solution produced
a strikingly efficient separation
and recovery process for the metals
from the positively charged electrode
of the battery, called the cathode.
" Because the cathode contains the critical
materials, it is the most expensive
part of any battery, contributing more
32
ORNL researchers Lu Yu and Yaocai Bai examine vials that contain a chemical solution that causes
the cobalt and lithium to separate from a spent battery, followed by a second stage when cobalt
precipitates in the bottom. (Image: Carlos Jones/ORNL)
than 30 percent of the cost, " said Yaocai
Bai, a member of the ORNL battery research
team. " Our approach could reduce
the cost of batteries over time. " The
research was conducted in ORNL's Battery
Manufacturing Facility.
The recycling technique developed
there leached nearly 100 percent of the
cobalt and lithium from the cathode
without introducing impurities in the system.
It also enabled efficient separation
of the metal solution from other residues.
Most importantly, it served a second
function by recovering over 96 percent
of the cobalt in a matter of hours,
without the typical addition of more
chemicals in what is usually a tricky process
of manually balancing acid levels.
" This is the first time one solution system
has covered the functions of both
leaching and recovery, " said lead researcher
Lu Yu. " It was exciting to find
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that the cobalt would precipitate and settle
out without further interference. We
were not expecting that. "
Eliminating the need for extra chemicals
reduces costs and avoids creating
byproducts or secondary wastes. The
leaching performance of citric acid and
ethylene glycol has been explored before,
but that approach used more acid
and a lower temperature, which proved
less effective, Bai said.
" We were surprised by how quickly the
leaching happened in our solution, " Bai
said. " With an organic acid, it usually
takes 10-12 hours, but this took only one. "
Conventional solutions using inorganic
acid are also slower because they include
water, which has a boiling point that limits
the temperature of the reaction.
For more information, contact S.
Heather Duncan at duncansh@ornl.gov;
478-718-9246.
Tech Briefs, June 2024

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Tech Briefs Magazine - June 2024

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