Nissan Motor and Nissan ARC announced on March 13, 2014 that they have developed an analysis method that can directly observe and quantify the movement of electrons in the positive electrode material of lithium-ion batteries during charging and discharging. Using this method, “makes the development of high-capacity lithium-ion batteries possible, thereby helping to extend the range of pure electric vehicles (EV)”

To develop a lithium-ion battery with high capacity and long life, it is necessary to store as much lithium as possible in the electrode active material, and design materials that can produce a large amount of electrons. For this reason, it is very important to grasp the movement of electrons in the battery, and the previous analysis techniques cannot directly observe the movement of electrons. Therefore, it is impossible to quantitatively identify which element in the electrode active material (manganese (Mn), cobalt (Co), nickel (Ni), oxygen (O), etc.) can release electrons.

The analysis method developed this time has solved the long-standing problem-the discovery of the origin of the current during charging and discharging and quantitatively grasping it for the “world’s first” (Nissan Motor). As a result, it is possible to accurately grasp the phenomena occurring inside the battery, especially the movement of the active material contained in the positive electrode material. The results this time were jointly developed by Nissan ARC, the University of Tokyo, Kyoto University, and Osaka Prefectural University.

Tesla energy storage battery

Also used the “Earth Simulator”

The analytical method developed this time uses both the “X-ray absorption spectroscopy” using the “L absorption end” and the “first-principles calculation method” using the supercomputer “Earth Simulator”. Although some people have used X-ray absorption spectroscopy to perform lithium-ion battery analysis before, the use of “K absorption end” is the mainstream. The electrons arranged in the K shell layer closest to the nucleus are bound in the atom, so the electrons do not directly participate in the charge and discharge.

The analysis method this time uses X absorption spectroscopy using the L absorption end to directly observe the flow of electrons participating in the battery reaction. In addition, by combining with the first-principles calculation method using the earth simulator, the amount of electron movement that could only be inferred before was obtained with high accuracy.

Those technology will make great impact for the Types of battery energy storage systems

Nissan ARC uses this analysis method to analyze lithium-excess cathode materials. It was found that (1) in the high-potential state, the electrons belonging to oxygen are beneficial to the charging reaction; (2) when discharging, the electrons belonging to the manganese are beneficial to the discharge reaction.

Battery energy storage system design