Optimum pressure to improve the performance of lithium metal batteries


Date:
October 18, 2021
Source:
University of California - San Diego
Summary:
A team of materials scientists and chemists has determined the
proper stack pressure that lithium metal batteries, or LMBs, need
to be subjected to during battery operation in order to produce
optimal performance.



FULL STORY ==========================================================================
A team of materials scientists and chemists has determined the proper
stack pressure that lithium metal batteries, or LMBs, need to be subjected
to during battery operation in order to produce optimal performance.


==========================================================================
The team, which includes researchers from the University of California
San Diego, Michigan State University, Idaho National Laboratory and the
General Motors Research and Development Center, presents their findings
in the Oct. 18 issue of Nature Energy.

Using lithium metal to replace the graphite for battery anodes is the
ultimate goal for part of the battery R&D field; these lithium-metal
batteries (LMBs) have the potential to double the capacity of
today's best lithium-ion technologies. For example, lithium metal battery-powered electric vehicles would have twice the range of
lithium-ion battery-powered vehicles, for the same battery weight.

Despite this advantage over lithium-ion batteries, LMBs are not considered
a viable option to power electric vehicles or electronics, because of
their short lifespan and potential safety hazards, specifically short
circuits caused by lithium dendrite growth. Researchers and technologists
had noticed that subjecting LMBs to pressure during battery cycling
increases performance and stability, helping to solve this lifespan
challenge. But the reasons behind this were not fully understood.

"We not only answered this scientific question, but also identified the
optimum pressure needed," said Shirley Meng, a professor in the UC San
Diego Department of NanoEngineering and the paper's senior author. "We
also proposed new testing protocols for maximum LMB performance."
In the Nature Energy study, researchers used several characterization
and imaging techniques to study LMB morphology and quantify performance
when the batteries were subjected to different pressures.



==========================================================================
They found that higher pressure levels force lithium particles to
deposit in neat columns, without any porous spaces in between. The
pressure required to achieve this result is 350 kilo Pascal (roughly
3.5 atmospheres). By contrast, batteries subjected to lower levels of
pressure are porous and lithium particles deposit in a disorderly fashion, leaving room for dendrites to grow.

Researchers also showed that the process doesn't affect the solid
electrolyte interphase (SEI) structure of the batteries' electrolytes.

But manufacturing facilities for LMBs would have to be retooled for this
new technique to be applied.

Another way to boost performance is to not completely discharge the
battery while it cycles. Instead, the researchers keep a reservoir of
lithium where re- nucleation can occur.

The researchers' findings were validated at the General Motors Research
and Development Center in Michigan.



========================================================================== Separately, researchers at Idaho National Laboratory use molecular
dynamics simulations to understand the stack pressure range used in
this work, which is much less than that expected based on macroscopic mechanical models.

Researchers explained the mechanistic origin of this unique process.

"Research institutions should keep collaborating with national
laboratories and industries to solve practical problems in the battery
field," said Chengcheng Fang, the paper's first author, who earned her
Ph.D. in Meng's research group and is now on faculty at Michigan State University.

Pressure-tailored lithium deposition and dissolution in lithium
metal batteries Chengcheng Fang, Bingyu Lu, Minghao Zhang, Diyi
Cheng, Miguel Ceja, Jean-Marie Doux and Y. Shirley Meng, Department
of NanoEngineering, University of California San Diego Chengcheng
Fang, Department of Chemical Engineering and Materials Science,
Michigan State University Gorakh Pawar and Boryann Liaw, Energy
and Environmental Science & Technology, Idaho National Laboratory
Shuru Chen and Mei Cai, General Motors Research and Development Center ========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Ioana
Patringenaru. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Fang, C., Lu, B., Pawar, G. et al. Pressure-tailored lithium
deposition
and dissolution in lithium metal batteries. Nat Energ, 2021 DOI:
10.1038/ s41560-021-00917-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211018112517.htm

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