Tech Briefs Magazine - November 2023 - 34

Power & Energy
Developing Fast-Charging Lithium-Metal Batteries
By growing uniform lithium crystals on a surprising surface, engineers have opened a new
door to fast-charging lithium-metal batteries.
University of California San Diego, La Jolla, CA
E
ngineers have made progress toward
lithium-metal batteries that charge as
fast as an hour. This fast charging is
thanks to lithium metal crystals that can
be seeded and grown - quickly and uniformly
- on a surprising surface. This
new approach, led by University of California
San Diego engineers, enables
charging of lithium-metal batteries in
about an hour, a speed that is competitive
against today's lithium-ion batteries.
The trick is to use a crystal growing surface
that lithium officially doesn't " like. "
From these seed crystals grow dense layers
of uniform lithium metal. Uniform layers
of lithium metal are of great interest to battery
researchers because they lack battery-performance-degrading
spikes called
dendrites. The formation of these dendrites
in battery anodes is a longstanding
roadblock to fast-charging ultra-energy-dense
lithium-metal batteries.
To grow lithium metal crystals, the researchers
replaced the ubiquitous copper
surfaces on the negative side (the anode)
of lithium-metal batteries with a lithiophobic
nanocomposite surface made of lithium
fluoride (LiF) and iron (Fe). Using this
lithiophobic surface for lithium deposition,
lithium crystal seeds formed, and
from these seeds grew dense lithium layers
- even at high charging rates. The result
was long-cycle-life lithium-metal batteries
that can be charged quickly.
" The special nanocomposite surface is
SEI
10.0kv X10,000 WD5.5mm 1µm
In this SEM image, large, uniform crystals of lithium metal grow on a surprising surface. (Image:
Zhaohui Wu and Zeyu Hui/UC San Diego)
the discovery, " said UC San Diego Nanoengineering
Professor Ping Liu. " We challenged
the traditional notion of what kind
of surface is needed to grow lithium crystals.
The prevailing wisdom is that lithium
grows better on surfaces that it likes, surfaces
that are lithiophilic. In this work, we show
that is not always true. The substrate we use
does not like lithium. However, it provides
abundant nucleation sites along with fast
surface lithium movement. These two factors
lead to the growth of these beautiful
crystals. This is a nice example of a scientific
insight solving a technical problem. "
While lithium-metal batteries hold great
potential for EVs and portable electronics
because of their high charge density, today's
lithium-metal batteries must be
charged extremely slowly in order to maintain
battery performance and avoid safety
problems. The new advance could eliminate
a significant roadblock that is holding
back widespread use of energy-dense lithium-metal
batteries for applications like
electric vehicles and portable electronics.
For more information, contact Daniel
Kane at dbkane@ucsd.edu.
Dry Manufacturing Process for EV Batteries
The method offers a path to cleaner, more affordable high-energy EV batteries.
Oak Ridge National Laboratory, Oak Ridge, TN
T
he lithium-ion batteries used to power
electric vehicles (EVs) are key to a
clean energy economy. But their electrodes
are usually made using a wet slurry
with toxic solvents, an expensive manufacturing
approach that poses health
and environmental risks.
Early experiments at the Department
of Energy's Oak Ridge National Laboratory
have revealed significant benefits to
a dry battery manufacturing process.
This eliminates the solvent while showing
promise for delivering a battery that
is durable, less weighed down by inactive
elements and able to maintain high en34
ergy
storage capacity after use. Such improvements
could boost wider EV adoption,
helping to reduce carbon emissions
and achieve U.S. climate goals.
Dry processing is a relatively new alternative
that saves factory floor space as
well as time, energy, waste disposal and
startup expenses, yet until now, researchers
have had limited understanding of
how and why it works.
ORNL and industry partner Navitas Systems
probed how the dry process affects the
structure of battery materials and their electrochemical
properties. Batteries generate
energy as lithium ions travel between elecwww.techbriefs.com
trodes
called the cathode and anode. The
team focused on an electrode dry processing
strategy, which involves mixing dry powders
with a binder, then compacting the
material to improve contact between the
particles. This strategy could be applied to
both the anode and cathode by focusing on
either certain materials or mixing methods.
After Navitas made the electrodes, ORNL
researchers led by Jianlin Li and Runming
Tao measured their electrochemical performance
in different conditions over various
time frames. The ORNL team was able to
reach a new understanding of how the
dry-processed electrodes degrade.
Tech Briefs, November 2023

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Tech Briefs Magazine - November 2023

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