Conceptual artwork depicting the ZULF-NMR measurement of a pouch-cell battery (center) using quantum sensors such as optically pumped magnetometers (OPMs, above) and superconducting quantum interference devices (SQUIDs, below) which can detect and quantify the minute magnetic fields generated by the nuclear spins of the molecules inside the battery electrolyte.
Illustration Credit: ©: F. Teleanu, A. Fabricant, using GPAI
Scientific Frontline: Extended "At a Glance" Summary: Non-Destructive Battery Testing via ZULF NMR"
The Core Concept: A novel diagnostic technique employing zero-to-ultra-low-field nuclear magnetic resonance (ZULF NMR) enables the non-destructive evaluation of electrolyte composition and volume inside sealed rechargeable batteries.
Key Distinction/Mechanism: Unlike conventional diagnostic methods that cannot penetrate metal housings, ZULF NMR operates without a strong external magnetic field. This renders the battery casing transparent to the scan, allowing quantum sensors to directly detect and quantify the minute magnetic fields generated by the nuclear spins of solvent and lithium salt molecules within the electrolyte.
Major Frameworks/Components:
- Zero-to-ultra-low-field nuclear magnetic resonance (ZULF NMR) operating independently of strong external magnetic fields.
- Quantum sensors, specifically optically pumped magnetometers (OPMs) and superconducting quantum interference devices (SQUIDs), used to detect molecular magnetic fields.
- Operando measurements for the real-time monitoring of realistically packaged commercial pouch-cell geometries.
Branch of Science: Physical Chemistry, Quantum Sensing, Materials Science, and Electrochemistry.
Future Application: This technology aims to facilitate real-time integrity testing of batteries during operation, optimize quality control throughout the lifecycle of electric vehicle and mobile device power cells, and guide the design of next-generation energy storage technologies.
Why It Matters: Electrolyte degradation, aging, and leakage in rechargeable batteries can lead to functional failure or dangerous thermal events, such as heat generation and explosions. Non-destructive monitoring provides crucial insights into internal electrochemical processes, ensuring safer and more reliable deployment of batteries critical for modern electronics and renewable energy storage.
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. An international research team involving the Helmholtz Institute Mainz (HIM), a branch of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Johannes Gutenberg University Mainz (JGU), Physikalisch-Technische Bundesanstalt in Berlin, and New York University has now addressed the question of how to enable nondestructive diagnosis of the electrolyte through the battery casing using special nuclear magnetic resonance techniques. The results have been published in the journal Chemical Science.
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.
Examinations with zero-to-ultra-low-field magnetic resonance
"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," said co-first author Dr. Anne Fabricant, who was involved in the experiments at both the HIM and the Physikalisch-Technische Bundesanstalt in Berlin. "We examine the batteries using what is known as zero-to-ultra-low-field magnetic resonance. The casings are transparent for this technique, allowing us to see inside." In this diagnostic technique, also known as ZULF NMR, nuclear magnetic resonance is measured without the influence of a strong external magnetic field.
"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," explained Professor Dmitry Budker, who works at HIM and JGU and is one of the champions of the ZULF NMR method. "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 as part of operando measurements. 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 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," says key project collaborator Professor Alexej Jerschow from New York University, who is a Carl-Zeiss-Humboldt Research Award recipient.
Dmitry Budker's research team is planning further experiments
Professor Budker's research team is planning further experiments to improve diagnostics. "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," said Budker. "I am convinced that in the long term, this technology will find its place alongside other, more invasive diagnostic methods."
Published in journal: Chemical Science
Authors: Anne M. Fabricant, Román Picazo-Frutos, Florin Teleanu, Gregory J. Rees, Raphael Kircher, Mengjiang Lin, William Evans, Paul-Martin Luc, Robert A. House, Peter G. Bruce, Peter Krüger, John W. Blanchard, James Eills, Kirill F. Sheberstov, Rainer Körber, Dmitry Budker, Danila A. Barskiy, and Alexej Jerschow
Source/Credit: Johannes Gutenberg University Mainz
Reference Number: chm030526_01
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