A new quantitative rule for designing better batteries

Osaka, Japan - A joint research team from The University of Osaka and Daikin Industries, Ltd. has identified a crucial new indicator for designing the advanced lithium-ion batteries. They discovered that the "electrolyte lithium-ion chemical potential"—a measure of how "uncomfortable" a lithium-ion is within a battery's electrolyte—quantitatively determines whether a battery can be charged and discharged reversibly. This finding paves the way for a shift from trial-and-error development to a rational, data-driven design process for safer and higher-performance batteries.

Lithium-ion batteries are essential to modern society, powering everything from smartphones to electric vehicles. To improve their performance, researchers have been searching for new electrolytes (the liquid medium that transports ions). However, a major challenge has been the lack of a clear guideline to predict whether a new electrolyte will work well with the graphite negative electrodes commonly used in these batteries. This has made electrolyte development a difficult, empirical process.

The research team revealed that the key lies in the lithium-ion chemical potential in an electrolyte. For a battery to charge properly, lithium ions must move from the electrolyte into the graphite electrode. The team clarified that this process occurs successfully only when the lithium ions are sufficiently "unstable" in the electrolyte—that is, when their chemical potential is high. This new metric provides a clear numerical standard to determine an electrolyte’s suitability, ending the guesswork. They also demonstrated that a newly developed fluorinated ether solvent, designed based on this concept, enables excellent battery performance.

This discovery enables a rational and highly efficient design of new electrolytes. By integrating the lithium-ion chemical potential into materials informatics, researchers can predict the performance of new materials, dramatically speeding up the development process. This will accelerate improvements in the performance, lifespan, and safety of batteries used in critical social infrastructure, such as electric vehicles, renewable energy storage systems, and uninterruptible power supplies for data centers.

“In this study, we did more than discover a new material,” says Dr. Yasuyuki Kondo, lead author of the study. “We identified the factor that actually governs charge–discharge reactions in lithium-ion batteries. We hope that our findings will accelerate future battery research and development and contribute to solving the world’s energy and economic challenges.”

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The article, “Electrolyte Li⁺ Chemical Potential Correlates with Graphite Negative Electrode Reactions in Lithium-Ion Batteries,” was published in Advanced Materials at DOI: https://doi.org/10.1002/adma.202514060

About The University of Osaka

The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.

Website: https://resou.osaka-u.ac.jp/en