Researchers in the US have used a gas mixture to increase the energy density of ‘lithium-rich’ cathode materials by up to 40%.
Scientists at the University of San Diego treated lithium-rich cathode particles with a carbon dioxide-based gas mixture to create oxygen vacancies throughout the surface of the particles.
The team showed the vacancies allowed lithium ions to move throughout the cathode more easily, which led to high discharge capacity and faster discharge rates.
Previously lithium-rich layered oxides’ potential to house more energy than other cathode materials was ruined by slow discharge rates and voltage fade.
In electrochemical tests, the treated material showed a discharge capacity of 300 milliamp-hours per gram with minimal voltage loss after 100 cycles.
The discovery paves the way to enhancing high-energy applications such as electric vehicles, said the group.
The findings were published in Nature Communications on July 1.
“We’re showing that oxygen plays a significant role in battery performance,” said Shirley Meng, nanoengineering professor at the University of California San Diego and a principal investigator of the study.
“This is a significant improvement with regards to the voltage fade problem, but there’s still a lot of work left to completely resolve this problem.
“With this study, we want to open a new pathway to explore more battery materials in which we can control oxygen activity.
Meng leads a group of international researchers investigating battery materials at the level of single atoms and molecules, and at the interfaces. To date its focus has been on lithium and transition metal atoms.
“Before we can decide if this is a promising step forward for batteries, we need to probe whether our technology can improve battery performance based on multiple metrics at once, not just whether it improves a single parameter,” Meng said.
Picture: A a SEM image of lithium-rich cathode particles treated with a carbon dioxide-based gas mixture to introduce oxygen vacancies on the surface. Credit: Laboratory for Energy Storage and Conversion, UC San Diego