Battery & Electrification Technology - November/December 2024 - 21

are most important in achieving good results.
To their surprise, just two of them - the
temperature and current at which the battery
is charged - stood out from all the rest.
Experiments confirmed that charging
at high currents has a huge impact, increasing
the lifespan of the average test
battery by 50 percent. It also deactivated
a much higher percentage of lithium up
front - about 30 percent, compared to 9
percent with previous methods - but
that turned out to have a positive effect.
Removing more lithium ions up front is a
bit like scooping water out of a full bucket
before carrying it, Cui said. The extra headspace
in the bucket decreases the amount
of water splashing out along the way. In
similar fashion, deactivating more lithium
ions during formation frees up headspace
in the positive electrode and allows the
electrode to cycle in a more efficient way,
improving subsequent performance.
" Brute force optimization by
trial-and-error
is routine in manufacturing
- how should we perform the first
charge, and what is the winning combination
of factors? " Chueh said. " Here, we
didn't just want to identify the best
recipe for making a good battery; we
wanted to understand how and why it
works. This understanding is crucial for
finding the best balance between battery
performance and manufacturing
efficiency. "
For more information, contact
communications@slac.stanford.edu.
Researchers Unveil Scalable Graphene Technology to
Revolutionize Battery Safety and Performance
Researchers have developed a pioneering technique for producing large-scale graphene current collectors.
Swansea University, Swansea, Wales, UK
T
his breakthrough promises to significantly
enhance the safety and performance
of lithium-ion batteries (LIBs),
addressing a critical challenge in energy
storage technology.
Published in Nature Chemical Engineering,
the study details the first successful protocol
for fabricating defect-free graphene
foils on a commercial scale. These foils
offer extraordinary thermal conductivity -
up to 1,400.8 W/(m·K) - nearly 10 times
higher than traditional copper and aluminum
current collectors used in LIBs.
" This is a significant step forward for
battery technology, " said Dr Rui Tan, colead
author from Swansea University.
" Our method allows for the production of
graphene current collectors at a scale
and quality that can be readily integrated
into commercial battery manufacturing.
This not only improves battery safety by
efficiently managing heat but also enhances
energy density and longevity. "
One of the most pressing concerns in the
development of high-energy LIBs, especially
those used in electric vehicles, is thermal
runaway - a dangerous scenario where excessive
heat leads to battery failure, often
resulting in fires or explosions. These
graphene current collectors are designed to
mitigate this risk by efficiently dissipating
heat and preventing the exothermic reactions
that lead to thermal runaway.
" Our dense, aligned graphene structure
provides a robust barrier against the
A scalable graphene current collector featuring high thermal and electrical conductivity has
been developed to address the crucial thermal problems in lithium-ion batteries. (Image:
Swansea University)
formation of flammable gases and prevents
oxygen from permeating the battery cells,
which is crucial for avoiding catastrophic
failures, " explained Dr Jinlong Yang, co-lead
author from Shenzhen University.
The newly developed process is not
just a laboratory success but a scalable
solution, capable of producing graphene
foils in lengths ranging from meters to
kilometers. In a significant demonstration
of its potential, the researchers produced
a 200-meter-long graphene foil with a
thickness of 17 micrometers. This foil retained
high electrical conductivity even
after being bent over 100,000 times,
making it ideal for use in flexible electronics
and other advanced applications.
This new approach also allows for
the production of graphene foils with
Battery & Electrification Technology, November/December 2024
customizable thicknesses, which could lead
to even more efficient and safer batteries.
This international collaborative research
team led by Prof Liqiang Mai and
Prof Daping He from Wuhan University
of Technology, Dr Jinlong Yang from
Shenzhen University and Dr Rui Tan
from Swansea University is continuing
to refine their process, with ongoing efforts
to reduce the thickness of the
graphene foils and further enhance their
mechanical properties, also exploring
this new material beyond Li-ion batteries,
such as redox flow batteries and sodium-ion
batteries, with the assistance
from Professor Serena Margodonna's
group at Swansea University.
For more information, contact Catrin
Newman at c.a.newman@swansea.ac.uk.
21

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