Novel Way to Boost the Performance of Solid-State Batteries

Although solid-state batteries can pack plenty of energy into a compact space, their electrodes are not that good at making a contact with their electrolytes.

Liquid electrolytes spark energy by reaching all nooks and corners of an electrode, but liquids also tend to take up a lot of space without preserving energy and also fail in due time.

Now, scientists have identified a new way to allow solid electrolytes to make contact with electrodes that are composed of strategically arranged materials—at the atomic level—and the outcomes are supporting the drive toward more improved solid-state battery technologies.

A new research work, headed by Paul Braun, materials science and engineering professor from the University of Illinois Urbana-Champaign; Beniamin Zahiri, a postdoctoral research associate; and John Cook, director of research and development from Xerion Advanced Battery Corp., has revealed that if the atomic alignment of solid materials is suitably controlled, it can enhance the stability and cathode-solid electrolyte interface of solid-state batteries.

The study results have been published in the Nature Materials journal.

With batteries, it’s not just materials that are important, but also how the atoms on the surfaces of those materials are arranged. Currently, solid-state battery electrodes contain materials with a large diversity of surface atom arrangements. This leads to a seemingly infinite number of electrode-solid electrolyte contact interface possibilities, all with different levels of chemical reactivity.

Beniamin Zahiri, Postdoctoral Research Associate, University of Illinois at Urbana-Champaign, News Bureau

“We are interested in finding which arrangements lead to practical improvements in battery cycle life, energy density, and power,” added Zahiri.

According to the researchers, the stability of an electrolyte controls the number of charge and discharge cycles that can be handled by a battery before it begins to lose power. Due to this aspect, investigators are rushing to identify the most stable electrolyte materials.

In the rush to find stable solid electrolyte materials, developers have sort of lost sight of the importance of what is happening in that very thin interface between electrolyte and electrode. But the stability of the electrolyte will not matter if the connection between it and the electrodes cannot be evaluated in an efficient way.

Beniamin Zahiri, Postdoctoral Research Associate, University of Illinois at Urbana-Champaign

In laboratory settings, the researchers constructed electrodes comprising lithium and sodium ions that have particular atomic arrangements.

They discovered certain correlations between the interface atomic arrangement and battery performance in both the sodium- and lithium-based solid-state batteries.

They also observed that controlling the atomic alignment of electrodes and reducing the interface surface area are crucial to both interpret the nature of interface instabilities and enhance the performance of cells.

This is a new paradigm for how to evaluate all the important solid electrolytes available today. Before this, we were largely just guessing what electrode-solid electrolyte interface structures gave the best performance, but now we can test this and find the best combination of materials and atomic orientations.

John Cook, Director of Research and Development, Xerion Advanced Battery Corp.

As revealed by Elif Ertekin, the study co-author and mechanical science and engineering professor, and her research team, having this amount of control gave the investigators the required data to run atomic simulations which according to them will result in much better electrolyte materials in the days to come, added the researchers.

“We think this will teach us a lot about how to investigate emerging solid electronics. We are not trying to invent new solid electrolytes; the materials world is doing a great job with that already. Our methodology will allow others to precisely measure the interfacial properties of their new materials, something that has otherwise been very difficult to determine, ”stated Braun.

Braun is also the Materials Research Laboratory director and an affiliate of mechanical science and engineering, chemistry, the Beckman Institute of Advanced Science and Technology, and the Holonyak Micro and Nanotechnology Laboratory at the University of Illinois Urbana-Champaign.

Ertekin is the director of mechanics programs in mechanical sciences and engineering and is also affiliated with the Materials Research Laboratory and the National Center for Supercomputing Applications.

The study was funded by the United States Army, the Department of Defense, and the Army Corps of Engineers.

Journal Reference:

Zahiri, B., et al. (2021) Revealing the role of the cathode-electrolyte interface on solid-state batteries. Nature Materials. doi.org/10.1038/s41563-021-01016-0.