Solid-state lithium-sulfur batteries: Neutrons unveil sluggish charge transport

Date:
April 5, 2023
Source:
Helmholtz-Zentrum Berlin fu"r Materialien und Energie
Summary:
Solid-state Lithium-Sulfur batteries offer the potential for
much higher energy densities and increased safety, compared to
conventional lithium- ion batteries. However, the performance of
solid-state batteries is currently lacking, with slow charging and
discharging being one of the primary causes. Now, a new study shows
that sluggish lithium ion transport within a composite cathode is
the cause of this slow charging and discharging.


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FULL STORY ==========================================================================
The scientists designed a special cell in order to observe the transport
of lithium-ions between the anode and the cathode in a solid-state Lithium-Sulfur battery. Since lithium can hardly be detected with
x-ray methods, HZB physicists Dr. Robert Bradbury and Dr. Ingo Manke
examined the sample cell with neutrons, which are extremely sensitive
to lithium. In conjunction with Dr.

Nikolay Kardjilov, HZB, they used neutron radiography and neutron
tomography methods on the CONRAD2 instrument at the Berlin neutron source
BER II1. Groups from Giessen (JLU), Braunschweig (TUBS) and Ju"lich
(FZJ) were also involved in the work.


========================================================================== Lithium ions observed directly "We now have much better idea what is
limiting the battery performance," says Bradbury: "We see from the
operando neutron radiography data that there is a reaction front of
lithium ions propagating through the composite cathode confirming the
negative influence of a low effective ionic conductivity." Additionally,
the 3D neutron tomography images show trapped lithium concentrated near
the current collector during recharging. "This results in a diminished
capacity because only some of the lithium is transported back when
the battery is charged." The observed lithium distribution was an
excellent fit to a model based on the theory of porous electrodes:
"What we observe here in the neutron imaging data correlates well with
the relevant electronic and ionic conductivity conditions from the model"
says Bradbury.

Bottleneck identified These results unveil a previously overlooked
development bottleneck for solid- state batteries, showing that
limitations exist in the cathode composites due to the slow ionic
transport. The challenge now is to enable faster ion delivery within the cathode composite. "Without direct visualization of the reaction front
inside the cathode composite this effect might have gone unnoticed,
despite its importance for solid-state battery development," Bradbury
says.

Footnote 1: The experiments took place at the end of 2019, before the
neutron source BER II was shut down. The work will be continued in the
future as part of the joint research group "NI-Matters" between HZB, the Institut Laue- Langevin (France) and the University of Grenoble (France).

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# Electronics # Energy_and_Resources # Telecommunications
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========================================================================== Story Source: Materials provided by Helmholtz-Zentrum_Berlin_fu"r_Materialien_und_Energie.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Robert Bradbury, Georg F. Dewald, Marvin A. Kraft, Tobias Arlt,
Nikolay
Kardjilov, Ju"rgen Janek, Ingo Manke, Wolfgang G. Zeier, Saneyuki
Ohno.

Visualizing Reaction Fronts and Transport Limitations in
Solid‐State Li-S Batteries via Operando Neutron
Imaging. Advanced Energy Materials, 2023; 2203426 DOI:
10.1002/aenm.202203426 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230405130127.htm

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