Tech Briefs Magazine - April 2024 - 26

UC Santa Cruz's group of researchers were the
winning team of the L2RPN Delft 2023, a competition
which invited participants from around
the world to use reinforcement learning or similar
techniques to operate a power grid. From
left to right: Qiuling Yang, Shourya Bose, and
Yu Zhang. (Image: Yu Zhang)
" We're modeling a whole bunch of
things - solar, wind, small generators,
batteries, and we're also modeling when
people's electricity demand changes, "
Bose said. " The novelty is that this specific
flavor of reinforcement learning, which
we call constrained policy optimization
(CPO), is being used for the first time. "
Their CPO approach takes into account
real-time conditions and uses machine
learning to find long-term patterns
that affect the output of renewables, such
as the varying demand on the grid at a
given time and intermittent weather factors
that affect renewable sources. This is
unlike traditional systems which often use
a technique called model predictive control
(MPC) that bases decisions simply on
the available conditions at the time of optimization.
For
example, if the CPO method predicts
that the sun will shine brightly in an
hour, it would use up its supply of solar energy
with the knowledge that it will later be
replenished - a different strategy than it
might take if the day was cloudy. It can also
learn about the system based on long-term
patterns of how the grid uses solar.
The researchers found that
their
CPO technique significantly outperforms
traditional MPC methods when
the forecasts of renewable sources are
lower than the reality because of its better
understanding of all the possible solar
profiles throughout any given day.
They also found that the reinforcement
learning controller is able respond
much faster than traditional optimization
methods in the moment of a
power outage.
Now that they've developed a successful
algorithm in simulations, the research
team is working to test their
model on microgrids in their lab. In the
long-term, the researchers hope to implement
their solution on the UC Santa
Cruz campus's energy system to address
outage issues that the residential campus
community faces.
For more information, contact Emily
Cerf at ecerf@ucsc.edu.
New Polymer Coating Could Boost EV Batteries
The advance opens up a new approach to developing EV batteries that are more affordable
and easier to manufacture.
Lawrence Berkeley National Laboratory, Berkeley, CA
R
esearchers at Lawrence Berkeley National
Laboratory (Berkeley Lab) have
developed a conductive polymer coating
- called HOS-PFM - that could enable
longer lasting, more powerful lithium-ion
(Li-ion) batteries for electric vehicles.
" The advance opens up a new approach
to developing EV batteries that are more
affordable and easy to manufacture, " said
Gao Liu, a Senior Scientist in Berkeley
Lab's Energy Technologies Area.
The HOS-PFM coating conducts both
electrons and ions at the same time. This
ensures battery stability and high
charge/discharge rates while enhancing
battery life. The coating also shows
promise as a battery adhesive that could
A) Pristine Al on copper
B)
Al/Cu Cycled
extend the lifetime of a Li-ion battery
from an average of 10 years to about 15
years, Liu added.
To demonstrate HOS-PFM's superior
conductive and adhesive properties, Liu
and his team coated aluminum and silicon
electrodes with HOS-PFM, and tested their
performance in a Li-ion battery setup.
Silicon and aluminum are promising
electrode materials for Li-ion batteries because
of their potentially high energy storage
capacity and lightweight profiles. But
these cheap and abundant materials quickly
wear down after multiple charge/discharge
cycles.
During experiments at the Advanced
Light Source and the Molecular FoundC)
HOS-PFM/AI/Cu
Cycled
ry, the researchers demonstrated that
the HOS-PFM coating significantly prevents
silicon- and aluminum-based electrodes
from degrading during battery
cycling while delivering high battery
capacity over 300 cycles, a performance
rate that's on par with today's state-ofthe-art
electrodes.
100 µm
100 µm
100 µm
The results are impressive, Liu said,
because silicon-based Li-ion cells typically
last for a limited number of charge/
discharge cycles and calendar life. The
researchers recently described these
findings in the journal Nature Energy.
The HOS-PFM coating could allow
the use of electrodes containing as
much as 80 percent silicon. Such high
silicon content could increase the energy
density of Li-ion batteries by at least
30 percent, Liu said. And because silicon
is cheaper than graphite, the standard
material for electrodes today,
cheaper batteries could significantly
increase the availability of entry-level
EVs, he added.
Berkeley Lab researchers demonstrated that the HOS-PFM coating significantly prevents aluminum-based
electrodes from degrading during battery cycling while delivering high battery capacity
over 300 cycles. From left: Scanning electron microscope images of aluminum on a copper bilayer
device before battery cycling (Figure A) and after (Figure B). Figure C shows a copper tri-layer device
with HOS-PFM coating after battery cycling. (Image: Gao Liu/Berkeley Lab. Courtesy of Nature Energy)
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The team next plans to work with
companies to scale up HOS-PFM for
mass manufacturing.
For more information contact Theresa
Duque at tnduque@lbl.gov; 510-495-2418.
Tech Briefs, April 2024

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Tech Briefs Magazine - April 2024

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