Findings Reveal Cause of Lithium-Ion Battery Self-Discharge

According to a study published in Science, an international team of scientists has discovered a startling element that speeds up the deterioration of lithium-ion batteries, resulting in a consistent loss of charge.

This finding offers a fresh perspective on battery life and methods to prevent self-discharge, which could enhance performance in numerous applications, including electric vehicles and smartphones.

It is still widely assumed that a fully charged battery's self-discharge results from lithium atom diffusion from the electrolyte to the battery's cathode, according to Artūras Vailionis, a visiting professor at the Lithuanian Kaunas University of Technology (KTU) and core lead of the X-ray and Surface Analysis group at Stanford University.

However, our study has shown that it is the diffusion of protons (hydrogen ions) that is causing a battery’s self-discharge. Based on the results of this study, it is possible to propose ways to extend the life of the battery by reducing self-discharge.

Artūras Vailionis, Visiting Professor, Faculty of Mathematics and Natural Sciences, Kaunas University of Technology

These methods may involve supplementing additives to the electrolyte, particularly those not containing hydrogen molecules like CH₂, or employing a unique coating to decrease the reaction of the cathode surface when in contact with the electrolyte.

Longer Battery Life for Eco-Friendly, Cost-Effective Technologies

According to Prof. Vailionis, self-discharge reduces the battery’s cyclic and calendar life and lowers its voltage and capacity over time. Understanding this problem is crucial for prevention as a lithium battery’s short lifespan impacts the environment and the economy.

Identifying a completely new phenomenon behind the batteries’ self-discharge could lead to more dependable, affordable, and environmentally friendly technologies.

Vailionis added, “The longer lifetime of lithium-ion batteries means that consumers need to change their batteries or electronic devices less often. Also, longer battery life helps to reduce the amount of electronic waste and prevents resource depletion – lithium, cobalt, and nickel are finite resources – thus contributing to more sustainable practices.”

Smartphones, laptops, and other devices with long-lasting batteries can be used for longer periods of time before needing to be recharged. In industrial applications that use large battery systems like grid energy storage or electric vehicles, longer battery life becomes a higher return on investment, making these technologies more cost-effective.

In renewable energy systems like wind and solar power, a more extensive battery life boosts the reliability and efficiency of energy storage whilst assisting in stabilizing the energy supply and decreasing fossil fuel dependence.

Longer battery life also lowers the chance of failure in crucial circumstances, crucial in defense, aerospace, and medical technologies.

Overall, longer battery life improves sustainability, economy, and productivity in a wide range of industrial applications.

Artūras Vailionis, Visiting Professor, Faculty of Mathematics and Natural Sciences, Kaunas University of Technology

Combined Efforts to Produce Results

A multinational team of scientists from several domains produced the study's findings. Vailionis’s Stanford University team utilized X-ray diffraction to investigate two distinct structures in the cathode, one deeper within the cathode and one at its surface impacted by hydrogen ions. X-ray reflectometry verified the presence of a surface layer containing hydrogen atoms.

Vailionis, a Stanford University researcher, has spent 13 years as a visiting professor at KTU in Lithuania. He participates in joint projects with KTU scientists and teaches a course on X-ray diffraction each year to the physics study program students.

He further added, “Since I left, Lithuania has changed beyond recognition: universities are getting much better funding for education, and they have access to European funds. Scientists and PhD students have great opportunities to go to other universities and research institutions to study, to go to conferences, and to share their research results.”

According to Vailionis, Lithuanian students have also changed. He concluded, “They are much more active in the class than they were in my time, and there are no problems with the English language.”

Journal Reference:

Wan, G. et. al. (2024) Solvent-mediated oxide hydrogenation in layered cathodes. Science. doi.org/10.1126/science.adg4687