US DOE Ames Laboratory Discovers Method for Improving Efficiency of Lithium Ion Batteries

Researchers at the U.S. Department of Energy’s Ames Laboratory have discovered a method for improving the energy efficiency of lithium ion batteries. The researchers bombarded graphite in an ultra-high vacuum environment with ions to create surface defects. Copper was then deposited on the ion-bombarded graphite while holding it at elevated temperature. The synthetic route created multi-layer copper islands that are completely covered by graphene layers.

“Copper is a highly conductive material but susceptible to oxidation. Being able to successfully embed it just underneath the surface of graphite protects the copper, and suggests a number of potential applications, including battery technology,” stated research assistant Ann Lii-Rosales, who leads the project.

The new technique follows on research conducted last year where the same team encapsulated dysprosium, a magnetic rare-earth metal, underneath a single layer of graphene. The success of that project led the team to begin testing the possibilities of the method with other elements, including copper.

“We’re pretty excited by this because we didn’t expect it,” said Pat Thiel, distinguished professor of chemistry and materials science and engineering at Iowa State University, who also works at the Ames Lab. “Copper doesn’t seem to interact strongly or favorably with graphitic materials at all, so this was a big surprise. It really challenges us to understand the reasons and mechanisms involved.”

This work was supported primarily by the U.S. Department of Energy Office of Science. It was also supported in part by a grant of computer time at the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility. The team’s results have been published in a paper titled “Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights,” in the Journal of Physical Chemistry C.