Rubber material holds key to long-lasting, safer EV batteries

Date:
January 12, 2022
Source:
Georgia Institute of Technology
Summary:
For electric vehicles (EVs) to become mainstream, they need cost-
effective, safer, longer-lasting batteries that won't explode
during use or harm the environment. Researchers may have found a
promising alternative to conventional lithium-ion batteries made
from a common material: rubber.



FULL STORY ==========================================================================
For electric vehicles (EVs) to become mainstream, they need
cost-effective, safer, longer-lasting batteries that won't explode
during use or harm the environment. Researchers at the Georgia Institute
of Technology may have found a promising alternative to conventional lithium-ion batteries made from a common material: rubber.


========================================================================== Elastomers, or synthetic rubbers, are widely used in consumer products
and advanced technologies such as wearable electronics and soft robotics because of their superior mechanical properties. The researchers found
that the material, when formulated into a 3D structure, acted as a
superhighway for fast lithium- ion transport with superior mechanical toughness, resulting in longer charging batteries that can go farther. The research, conducted in collaboration with the Korea Advanced Institute
of Science and Technology, was published Wednesday in the journal Nature.

In conventional lithium-ion batteries, ions are moved by a liquid
electrolyte.

However, the battery is inherently unstable: even the slightest damage
can leak into the electrolyte, leading to explosion or fire. The safety
issues have forced the industry to look at solid-state batteries, which
can be made using inorganic ceramic material or organic polymers.

"Most of the industry is focusing on building inorganic solid-state electrolytes. But they are hard to make, expensive and are not
environmentally friendly," said Seung Woo Lee, associate professor in the George W. Woodruff School of Mechanical Engineering, who is part of a team
of researchers who have uncovered a rubber-based organic polymer superior
to other materials. Solid polymer electrolytes continue to attract great interest because of their low manufacturing cost, non-toxicity and soft
nature. However, conventional polymer electrolytes do not have sufficient
ionic conductivity and mechanical stability for reliable operation of solid-state batteries.

Novel 3D Design Leads to Jump in Energy Density, Performance Georgia
Tech engineers have solved common problems (slow lithium-ion transport
and poor mechanical properties) using the rubber electrolytes. The key breakthrough was allowing the material to form a three-dimensional
(3D) interconnected plastic crystal phase within the robust rubber
matrix. This unique structure has resulted in high ionic conductivity,
superior mechanical properties and electrochemical stability.

This rubber electrolyte can be made using a simple polymerization
process at low temperature conditions, generating robust and smooth
interfaces on the surface of electrodes. These unique characteristics
of the rubber electrolytes prevent lithium dendrite growth and allow for
faster moving ions, enabling reliable operation of solid-state batteries
even at room temperature.

"Rubber has been used everywhere because of its high mechanical
properties, and it will allow us to make cheap, more reliable and safer batteries," said Lee.

"Higher ionic conductivity means you can move more ions at the same time,"
said Michael Lee, a mechanical engineering graduate researcher. "By
increasing specific energy and energy density of these batteries, you
can increase the mileage of the EV." The researchers are now looking at
ways to improve the battery performance by increasing its cycle time and decreasing the charging time through even better ionic conductivity. So
far, their efforts have seen a two-time improvement in the battery's performance / cycle time.

The work could enhance Georgia's reputation as a center for EV
innovation. SK Innovation, a global energy and petrochemical company,
is funding additional research of the electrolyte material as part of
its ongoing collaboration with the Institute to build next-generation solid-state batteries that are safer and more energy dense than
conventional LI-ion batteries. SK Innovation recently announced
construction of a new EV battery plant in Commerce, Georgia, expected to produce an annual volume of lithium-ion batteries equal to 21.5 Gigawatt-
hours by 2023.

"All-solid-state batteries can dramatically increase the mileage and
safety of electric vehicles. Fast-growing battery companies, including SK Innovation, believe that commercializing all-solid-state batteries will
become a game changer in the electric vehicle market," said Kyounghwan
Choi, director of SK Innovation's next-generation battery research
center. "Through the ongoing project in collaboration with SK Innovation
and Professor Seung Woo Lee of Georgia Tech, there are high expectations
for rapid application and commercialization of all-solid-state batteries." ========================================================================== Story Source: Materials provided by Georgia_Institute_of_Technology. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Michael J. Lee, Junghun Han, Kyungbin Lee, Young Jun Lee, Byoung
Gak Kim,
Kyu-Nam Jung, Bumjoon J. Kim, Seung Woo Lee. Elastomeric
electrolytes for high-energy solid-state lithium batteries. Nature,
2022; 601 (7892): 217 DOI: 10.1038/s41586-021-04209-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220112121455.htm
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