Scientists Develop New Method for Non-destructive Battery Testing
International team of researchers harnesses nuclear magnetic resonance to “see inside” reusable batteries
Rechargeable batteries are everywhere – from portable electronic devices and electric vehicles to renewable energy storage. Battery failures are often due to the loss or chemical degradation of the electrolyte, a substance that allows electrical current to flow within a battery.
An international research team involving New York University, along with the Helmholtz Institute Mainz, Johannes Gutenberg University Mainz, and Physikalisch-Technische Bundesanstalt in Berlin, has determined how to measure the battery electrolyte without opening the housing of a battery cell. The results have been published in the journal Chemical Science.
Study author Alexej Jerschow, professor of chemistry at New York University, says:
The ability to nondestructively characterize electrolyte volume and composition supports superior battery design and serves as a vital quality control tool throughout a cell’s lifecycle,
ZULF NMR setup for battery testing at the Helmholt Institute Mainz. Credit © A. Fabricant
How does a rechargeable battery work?
A battery stores electrical energy in chemical form. Inside are two metal electrodes and a medium called electrolyte. During discharge, chemical reactions take place in which charged particles migrate inside, while electrons flow through the external circuit, supplying electrical energy. In a rechargeable battery, this process can be reversed: charging resets the chemical processes so that the energy storage device can be used again. Over many charging cycles, the electrolyte changes, ages, or can leak, which can lead to the battery becoming unusable or, in the worst case, even pose a hazard due to heat generation or explosion.
Co-first author Anne Fabricant, who was involved in the experiments at both the Helmholtz Institute Mainz and the Physikalisch-Technische Bundesanstalt in Berlin, says:
Reliable methods for nondestructive testing of the battery condition are currently lacking, as the quantity and chemical composition of the electrolyte cannot be determined through the housing using conventional techniques.
”This is exactly where our research comes in,”
A new test for reusable batteries
The researchers examined the batteries using what is known as zero-to-ultra-low-field magnetic resonance (or ZULF NMR). The casings are transparent for this technique, allowing them to see inside.
Dmitry Budker, professor at Helmholtz Institute Mainz and Johannes Gutenberg University Mainz, explains:
In our tests, we were able to demonstrate the direct detection and quantification of both the solvent and the lithium salt components of commercial electrolytes through metal battery casings,
“These were realistically packaged battery cells, including so-called pouch-cell geometries used in electric vehicles. We have thus proven the concept and paved the way for a practical application of the technology.”
In the future, ZULF NMR could be used to test the integrity of rechargeable batteries during operation. This is a topic of increasing importance, as these batteries have many usages—for example in small mobile devices such as cell phones and notebooks, but also on a large scale in electric vehicles. They are particularly relevant for the storage of renewable energies. In addition, the measurements provide a deeper understanding of electrochemical processes and the development of next-generation battery cell technologies.
The researchers are planning further experiments to improve diagnostics.
Budker, says:
We have many ideas on how we can make detection more accurate and faster, how we can examine larger batteries, and how the process can be made more cost-efficient,
“I am convinced that in the long term, this technology will find its place alongside other, more invasive diagnostic methods.”
Jerschow conducted this research as a recipient of the Carl-Zeiss-Humboldt Research Award. The work was also supported by the Deutsche Forschungsgemeinschaft, National Science Foundation (CHE 2108205 and CHE 2505792), and American Chemical Society (PRF 68117-ND6), among others.
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