Researchers predict materials for stable lithium-ion batteries with high recording capacity

A research team at Northwestern University has found a way to stabilize new batteries, which have a high recording capacity. Based on a lithium manganese oxide cathode, this breakthrough can extend the life of smart phones and battery-powered vehicles by more than two times.

“This battery electrode has achieved one of the highest capacity ever reported in all transition metal oxide based electrodes, and it is currently more than twice the material capacity of a cell phone or laptop,” Jerome B. Christopher Wolfton said. Professor Cohen, Department of Materials Science and Engineering, Northwest McCormick School of Engineering, responsible for the study said: "This high capacity will represent a huge step forward in lithium-ion batteries for electric vehicles."

The study was published online on May 14th at Science Advances.

Lithium-ion batteries work by shuttle lithium ions back and forth between the anode and the cathode. The cathode is made of a compound containing lithium ions, a transition metal, and oxygen. The transition metal (usually cobalt) effectively stores and releases electrical energy as it moves from the anode to the cathode and back. The capacity of the cathode is then limited by the amount of electrons in the transition metal involved in the reaction.

A French research team first reported large-capacity lithium manganese oxide compounds in 2016. By replacing traditional cobalt with cheaper manganese, the team developed a cheaper electrode that more than doubled in capacity. But this is not without challenges. During the first two cycles, the performance of the battery dropped significantly, and the researchers did not consider it commercially viable. They also do not fully understand the large-volume or degraded chemical sources.

After detailed descriptions of the atomic map of the cathode atom, Wolfton's team discovered the reason behind the high capacity of the material: it forces oxygen to participate in the reaction process. In addition to transition metals, the battery has a higher ability to store and use lithium by using oxygen to store and release electrical energy.

Next, the Northwest team turned its attention to stabilizing the battery to prevent its rapid degradation.

“With the knowledge of the charging process, we use high-throughput calculations to scan the periodic table of elements and find new ways to synthesize this compound with other elements that improve battery performance,” says ZhenpengYao, who is the first author, the paper and Former doctor, students at Wolfton Labs.

The calculation identified two elements: chromium and vanadium. The team predicts that mixing the elements with lithium manganese oxide will result in a stable compound that will maintain the high capacity of the cathode as never before. Next, Wolfton and his collaborators will test these theoretical compounds experimentally in the lab.

The study was supported by the Center for Electrochemical Energy Science, a DE-AC02-06CH11357 Energy Frontier Research Center funded by the Department of Basic Energy Sciences of the US Department of Energy's Science Office. Yao, a postdoctoral researcher at Harvard University, and SooKim, a postdoctoral fellow at the Massachusetts Institute of Technology, are both former members of the Wolfton lab and the first author of the paper.

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