MRI Technique Tracks Battery Degradation in Real Time

Researchers from Tohoku University have developed a technique to study and identify metal ion dissolution in lithium-ion battery cathodes. Using Nuclear Magnetic Resonance Imaging (MRI), they could observe the dissolution process directly and in real time. Their findings were published in Communications Materials.

Rechargeable lithium-ion batteries are widely used in electronic devices and electric vehicles due to their cost efficiency and high voltage operation. However, their performance degrades with repeated use, raising concerns about safety as they age.

One factor contributing to this performance decline is the dissolution of metal ions from the cathode into the electrolyte. Studying this process has been challenging due to the small quantities involved. Understanding where, when, and how much dissolution occurs is crucial for improving battery performance and longevity.

The results of the present study show that the dissolution of a very small amount of manganese (Mn) can be detected with high sensitivity by MRI and visualized in real-time, which can greatly accelerate the speed of research.

Nithya Hellar, Researcher, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University

Magnetic resonance imaging (MRI) is a medical imaging technique that generates scans using a combination of radio waves and magnetic fields. Contrast agents such as gadolinium are used to enhance the visibility of specific regions in an MRI image. Gadolinium, a paramagnetic material, alters the magnetic properties of targeted areas, improving their visibility in MRI scans.

Researchers at Tohoku University applied this principle to study the dissolution of manganese ions (Mn²⁺) from a spinel-type LiMn₂O₄ cathode in a commercial battery electrolyte, LiPF₆ EC: DMC. Because Mn²⁺ is paramagnetic, its dissolution should result in increased signal intensity in MRI images. The researchers confirmed this effect, enabling real-time observation of the dissolution process.

The study also investigated the potential suppression of Mn²⁺ dissolution using an alternative electrolyte system. The researchers tested an electrolyte system, LiTFSI MCP, developed by the MEET (Münster Electrochemical Energy Technology) Battery Research Center at the University of Münster, Germany. They hypothesized that this electrolyte system would prevent metal ion dissolution.

MRI imaging showed no significant increase in signal intensity when using LiTFSI MCP, suggesting that Mn²⁺ dissolution did not occur.

This testing method provides a valuable approach for “exploring the metal ion dissolution in any electrochemical systems under different electrochemical conditions, such as changing the electrolyte solution, salt, electrodes, and additives. This identification method may help design lithium battery materials and improve their performance,” said Junichi Kawamura, Emeritus Professor at Tohoku University.

The findings indicate that this technique could be used to further investigate battery chemistry and assess alternative battery technologies.

We believe the method developed here can answer the long-time unanswered question of when, where, and how the metal ion dissolution occurs in the lithium-ion battery electrode and can be extended to other electrochemical systems.

Nithya Hellar, Researcher, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University

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Journal Reference:

Hellar, N., et al. (2025) Direct observation of Mn-ion dissolution from LiMn₂O₄ lithium battery cathode to electrolyte. Communications Materials. doi.org/10.1038/s43246-025-00733-2.