American researchers have discovered a new method that can stabilize the performance of high-energy-storage batteries!

　　said Christopher Wolverton, Professor of Materials Science and Engineering, McCormick School of Engineering, Northwestern University, USA.

　　"The high capacity of this electrode shows that it has a huge improvement in the goal of lithium-ion batteries for electric vehicles." Christopher added.

　　This research was reported online in the Journal of Scientific Development on May 18.

　　Lithium ion batteries work by reciprocating lithium ions between the positive and negative electrodes. The positive electrode is made of a compound containing lithium ions, transition metals and oxygen. Transition metal, usually cobalt, effectively stores and releases electrical energy when lithium ions move back and forth between the positive and negative electrodes. The capacity of the positive electrode is therefore limited by the number of electrons in the transition metal participating in the reaction.

　　A French research team first identified the performance of large-capacity lithium manganese oxide in 2016. By using lower-cost manganese to replace the traditional cobalt, the researchers developed a cheaper electrode with twice the capacity before. But it is also not perfect. Since battery performance will be greatly reduced during the first two cycles, scientists believe that it cannot be applied to the market. At the same time, they did not fully understand the chemical causes of battery degradation and its large capacity.

　　After drawing a comprehensive image of the positive electrode connected between atoms, Wolverton's team discovered the reason behind the high performance of the material: it drives oxygen to participate in the reaction process. By using oxygen and transition metals to store and release electrical energy, batteries have a larger capacity to store and utilize more lithium.

　　Subsequently, the Northwestern University team turned their research and development focus to how to stabilize the battery performance and prevent its rapid degradation.

　　"With the aid of charging process theory, we use high-speed calculations to thoroughly search the periodic table of elements to find ways to alloy compounds containing other elements to enhance the performance of the battery."

　　The co-first author of the article, said Zhenpeng Yao, a former doctoral student in the Wolverton laboratory.

　　The calculation identified two possible effective elements: vanadium and chromium. The research team predicts that mixing lithium manganese oxide with one of them will produce a stable compound that can maintain the unparalleled performance of the positive electrode. Later, Wolverton and his partner will test these theoretical compounds in the laboratory.

　　As part of the Center for Electrochemical Energy Science, the Center for Energy Frontier Research funded by the Bureau of Science of the US Department of Energy, this research was supported by its Basic Energy Science Project (Project Code: DE-AC02-06CH11357). Yao, a postdoctoral researcher at Harvard University, and SooKim, a postdoctoral researcher at MIT, are former members of the Wolverton laboratory and serve as the co-first authors of the article.