Unplanned discoveries, such as batteries, fuel cells, and devices that convert heat into electricity, can lead to vital discoveries in the future.
Scientists frequently conduct research by carefully selecting a research problem, developing a plan to solve it, and putting that plan into action. Unexpected discoveries, on the other hand, can happen along the way.
While working at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, Professor Mercouri Kanatzidis made an unexpected discovery while looking for a new superconductor with unusual properties. It was a material with a thickness of only four atoms that could study the motion of charged particles in two dimensions. This research could lead to the development of new materials for a variety of energy conversion devices.
“Our analysis shows that, prior to this transition, silver ions were fixed in a small space within our material’s two dimensions, but after this transition, they were shaken.” Mercouri Kanatzidis, Argonne, and Northwestern University have all been appointed as co-appointees.
Kanatzidis’ preferred material is a mix of silver, potassium, and selenium (a-KAg).
a-KAg is four-tiered structure resembling a wedding cake. These two-dimensional materials have lengths and widths, but they are very thin because they are only four atoms high.
When superconducting materials are cooled to extremely low temperatures, they lose all resistance to electron movement. “Unfortunately, this material was not and could not become a superconductor,” said Kanatzidis, a senior scientist in the Department of Materials Science at Argonne (MSD). “However, much to my surprise, he turned out to be an excellent example of a superionic driver.”
Ions charged in solid materials move freely in superionic conductors, similar to liquid electrolytes found in batteries. This results in a solid with unusually high ionic conductivity, which is a measure of a solid’s ability to conduct electricity. Because of the high ionic conductivity, the thermal conductivity is low. In other words, heat is difficult to pass through. Superionic conductors are supermaterials for energy storage and conversion devices due to their unique properties.
-KAg3Se2, a 2D superionic conductor, has a 4-layer atomic structure. When heated from 450 to 600 degrees, the team discovered a material with special properties for the first time.
“Our analysis reveals that, prior to this transition, silver ions were anchored in a small space within our material’s two dimensions,” Kanatzidis said. “However, they move after that transition.” Much is known about how ions move in three dimensions, but little is known about how they move in two dimensions. There isn’t much information.”
Scientists have long sought exemplary materials to study the movement of ions in 2D materials. This layered potassium-silver-selenium material appears to be so. The team measured the diffusion of ions within this solid and discovered that it was comparable to the highly salty water electrolyte, one of the fastest known ionic conductors.
It is too early to tell whether this superior material will be used in practice, but it will soon serve as a critical platform for the design of other 2D materials with high ionic conductivity and low thermal conductivity. There is an opportunity.
“These properties are critical for anyone designing new solid 2D electrolytes for batteries and fuel cells,” said Duck Young Chung, an MSD materials expert.
This superionic material research could also aid in the development of new thermoelectric elements that convert heat into electricity in power plants, industrial processes, and even the escape of automobile emissions. These investigations can also be used to develop membranes for environmental purification and water desalination.
This research was published in the journal Materials of Nature. “Type I two-dimensional superionic conductor,” an article. Authors include Alexander JE Rettie, Jingxuan Ding, Xiuquan Zhou, Michael J. Johnson, Christos D. Malliakas, Naresh C. Osti, Raymond Osborn, Olivier Delaire, and Stephan Rosenkranz, in addition to Kanatzidis and Chung. Researchers from Argonne, Northwest, the Department of Energy’s Oak Ridge National Laboratory, University College London, and Duke University are part of the team.