An international team of researchers has demonstrated a new way to increase the robustness and energy storage capability of a particular class of "lithium-rich" cathode materials — by using a carbon dioxide-based gas mixture to create oxygen vacancies at the material's surface. Researchers said the treatment improved the energy density — the amount of energy stored per unit mass — of the cathode material by up to 30 to 40 percent.The discovery sheds light on how changing the oxygen composition of lithium-rich cathode materials could improve battery performance, particularly in high-energy applications such as electric vehicles. The findings were published July 1 in Nature Communications."We've uncovered a new mechanism at play in this class of lithium-rich cathode materials. With this study, we want to open a new pathway to explore more battery materials in which we can control oxygen activity," said Shirley Meng, nanoengineering professor at the University of California San Diego and one of the principal investigators of the study.