Batteries: Passivation layer mystery solved
Researchers characterized chemical processes at the electrodes of
lithium-ion batteries

Date:
March 21, 2023
Source:
Karlsruher Institut fu"r Technologie (KIT)
Summary:
In our daily lives, lithium-ion batteries have become
indispensable. They function only because of a passivation layer
that forms during their initial cycle. As researchers found out
via simulations, this solid electrolyte interphase develops not
directly at the electrode but aggregates in the solution. Their
findings allow the optimization of the performance and lifetime
of future batteries.


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FULL STORY ==========================================================================
In our daily lives, lithium-ion batteries have become indispensable. They function only because of a passivation layer that forms during their
initial cycle. As researchers at Karlsruhe Institute of Technology (KIT)
found out via simulations, this solid electrolyte interphase develops not directly at the electrode but aggregates in the solution. The scientists
report on their study in the Advanced Energy Materials journal. Their
findings allow the optimization of the performance and lifetime of
future batteries.


==========================================================================
From smartphones to electric cars -- wherever a mobile energy source
is required, it is almost always a lithium-ion battery that does the
job. An essential part of the reliable function of this and other
liquid electrolyte batteries is the solid electrolyte interphase
(SEI). This passivation layer forms when voltage is applied for the first
time. The electrolyte is being decomposed in the immediate vicinity
of the surface. Until now, it remained unclear ow the particles in
the electrolytes form a layer that is up to 100 nanometers thick on
the surface of the electrode since the decomposition reaction is only
possible in a few nanometers distance from the surface.

The passivation layer on the anode surface is crucial to the
electrochemical capacity and lifetime of a lithium-ion battery because
it is highly stressed with every charging cycle. When the SEI is
broken up during this process, the electrolyte is further decomposed
and the battery's capacity is reduced -- a process that determines the
lifetime of a battery. With the right knowledge on the SEI's growth and composition, the properties of a battery can be controlled. But so far,
no experimental or computer-aided approach was sufficient to decipher
the SEI's complex growth processes that take place on a very wide scale
and in different dimensions.

Study as Part of the EU Initiative BATTERY 2030+ Researchers at the
KIT Institute of Nanotechnology (INT) now managed to characterize the
formation of the SEI with a multi-scale approach. "This solves one of
the great mysteries regarding an essential part of all liquid electrolyte batteries -- especially the lithium-ion batteries we all use every day,"
says Professor Wolfgang Wenzel, director of the research group "Multiscale Materials Modelling and Virtual Design" at INT, which is involved in
the large-scale European research initiative BATTERY 2030+ that aims
to develop safe, affordable, long-lasting, sustainable high-performance batteries for the future. The KIT researchers report on their findings
in the journal Advanced Energy Materials.

More than 50,000 Simulations for Different Reaction Conditions To examine
the growth and composition of the passivation layer at the anode of liquid electrolyte batteries, the researchers at INT generated an ensemble of
over 50,000 simulations representing different reaction conditions. They
found that the growth of the organic SEI follows a solution-mediated
pathway: First, SEI precursors that are formed directly at the surface
join far away from the electrode surface via a nucleation process. The subsequent rapid growth of the nuclei leads to the formation of a porous
layer that eventually covers the electrode surface. These findings
offer a solution to the paradoxical situation that SEI constituents can
form only near the surface, where electrons are available, but their
growth would stop once this narrow region is covered. "We were able
to identify the key reaction parameters that determine SEI thickness,"
explains Dr. Saibal Jana, postdoc at INT and one of the authors of the
study. "This will enable the future development of electrolytes and
suitable additives that control the properties of the SEI and optimize
the battery's performance and lifetime." (or)
* RELATED_TOPICS
o Matter_&_Energy
# Batteries # Fuel_Cells # Nature_of_Water #
Energy_and_Resources
o Computers_&_Math
# Computer_Modeling # Neural_Interfaces #
Distributed_Computing # Mobile_Computing
* RELATED_TERMS
o Lithium o Acid o Battery_(electricity) o Chlorine o Cadmium
o Computer_simulation o Alternative_fuel_vehicle o Solubility

========================================================================== Story Source: Materials provided by
Karlsruher_Institut_fu"r_Technologie_(KIT). Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Meysam Esmaeilpour, Saibal Jana, Hongjiao Li, Mohammad
Soleymanibrojeni,
Wolfgang Wenzel. A Solution‐Mediated Pathway for the
Growth of the Solid Electrolyte Interphase in Lithium‐Ion
Batteries. Advanced Energy Materials, 2023; 2203966 DOI:
10.1002/aenm.202203966 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230321112637.htm

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