Automotive Engineering - March 2023 - BET26

Anode-Free Lithium Batteries with Maximized
Energy Density
The newly developed battery has a volumetric energy density 40 percent higher than the conventional batteries.
Pohang University of Science and Technology, South Korea
T
he core materials that determine the
battery life and charging speed of
now commonly seen electric vehicles
(EVs) are anode materials. Korea's domestic
battery industry has been committed
to finding revolutionary ways to increase
the battery capacity by introducing new
technologies or other anode materials. A
POSTECH research team led by Professor
Soojin Park and PhD candidate Sungjin
Cho (Department of Chemistry) in collaboration
with Professor Dong-Hwa Seo
and Dr. Dong Yeon Kim (School of Energy
and Chemical
Engineering)
at
Ulsan
Institute of Science and Technology
(UNIST) have developed anode-free lithium
batteries with performance of long
battery life on a single charge.
The newly developed anode-free battery
has a volumetric energy density of 977
Wh/L which is 40 percent higher than
the conventional batteries (700 wh/L). This
means that the battery can run for 630 km
on a single charge. The study recently published
in Advanced Functional Materials and
was funded by the Alchemist project.
Batteries usually change the structure
of anode materials as lithium ions flow to
and from the electrode during repetitive
charging and discharging. This is why the
Fabrication process of anode-free electrode
Carbon
black
Branched
PEI
In-situ
SEI formation
Ag
nanoparitcles
LiNO3
Fabrication process of anode-free elctrode. An electrode was manufactured by coating an
ion-conductive layer composed of polyethyleneimine polymer, silver, lithium salt, and carbon
black on the surface of a copper current collector. The ion-conductive substrate fabricated this
way can operate the batteter by effectively receiving and releasing lithium ions during
charging and discharging. (Image: Pohang University of Science and Technology)
battery capacity decreases over time. It was
thought that if it was possible to charge
and discharge only with a bare anode
current collector without anode materials,
the energy density, which determines the
battery capacity, would increase. However,
this method had a critical weakness which
causes significant swelling of the anode
volume and reduces the battery lifecycle. It
swelled because there was no stable storage
for lithium in the anode.
To overcome this issue, the research team
succeeded in developing an anode-free battery
in a commonly used carbonate-based
liquid electrolyte by adding an ion-conductive
substrate. The substrate not only forms
an anode protective layer but also helps
minimize the bulk expansion of the anode.
The study shows that the battery maintained
high capacity of 4.2 mAh cm-2
high current density of 2.1 mA cm-2
and
for a
long period in the carbonate-based liquid
electrolyte. It was also proven both in
theory and through experiments that substrates
can store lithium.
Further, the team successfully demonstrated
the solid-state half-cells by using
Argyrodite-based sulfide-based solid electrolyte.
It is anticipated that this battery
will accelerate the commercialization of
non-explosive batteries since it maintains
high capacity for longer periods.
For more information, visit https://
postech.ac.kr/eng/e-postech/.
N-rich
SEI
Lithiation
Stable Li
deposition
Delithiation
Simplifying the Production of Lithium-ion Batteries
MIT spinout 24M Technologies designed a method that reduces the cost of manufacturing lithium-ion cells.
Massachusetts Institute of Technology, Cambridge, MA
W
26
hen it comes to battery innovations,
the importance of production
processes for bringing down
costs is often overlooked. Now the MIT
spinout 24M Technologies has simplified
lithium-ion (Li-ion) battery production
with a new design that requires fewer
materials and steps to manufacture each
cell. According to the company the design,
which it calls " SemiSolid " for its use
of gooey electrodes, reduces production
costs by up to 40 percent. The approach
also improves the batteries' energy density,
safety, and recyclability.
" The SemiSolid platform has been
proven at the scale of hundreds of megawatts
being produced for residential energy-storage
systems. Now we want to
prove it at the gigawatt scale, " said 24M
CEO Naoki Ota, whose team includes
24M Co-Founder, Chief Scientist, and MIT
Professor Yet-Ming Chiang.
Establishing large-scale production
lines is only the first phase of 24M's
plan. Another key draw of its battery
design is that it can work with different
combinations of Li-ion chemistries. That
means 24M's partners can incorporate
better-performing materials down the
line without substantially
changing
manufacturing processes.
The kind of quick, large-scale production
of next-generation batteries that
Battery & Electrification Technology, March 2023

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Automotive Engineering - March 2023

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