Nissan’s electron focus promises EV battery performance gains
Improved understanding through direct observation of electron activity in the cathode material of lithium ion batteries is a key step to boosting battery performance of electric vehicles. Nissan believes that applying the analysis technique to future research and design of battery materials could enable high-capacity and high-durability batteries developed that may extend the driving distance of zero emission EVs and improve their durability.
The analysis method, which was a joint R&D effort between Nissan Arc and Tokyo University, Kyoto University and Osaka Prefecture University, combines x-ray absorption spectroscopy that utilizes L-absorption edges and the first principle calculation from Japan’s Earth Simulator supercomputer.
The analysis method, which enables scientists to understand how electrons are orginated during charging and discharging, will help the observation and monitoring of the active materials within electrodes.
“Creating this analysis technique was a major step toward the further development of high-capacity, next-generation lithium ion batteries. It will play an important part in our future R&D aimed at extending the driving range of future zero emission vehicles," explained Takao Asami, Nissan senior vice president and president of Nissan Arc Ltd.
To develop high-capacity, long-life lithium ion batteries, the maximum amount of lithium needs to be stored in the electrode’s active material, which allows it to generate the highest possible number of electrons. To develop such a material, an accurate reading of the electron activity inside the
battery is vital. The new analysis method allows engineers to identify where electrons are being emitted from the active materials (manganese, cobalt, nickel and oxygen) in electrodes. The technique also can see how many electrons are emitted.
X-ray absorption spectroscopy had been used in the past to analyze batteries. However, the majority of this analysis was done using K-absorption edges that
can only observe restrained electrons in the atom (electrons that are not involved in the charging and discharging due to the vicinity to the nucleus) and not the actual electrons involved in cell reaction. By applying x-ray absorption spectroscopy that utilizes L-absorption edges, electrons that were directly involved with the cell reaction can be observed.
Nissan Arc has used the new analysis technique to investigate lithium-rich high-capacity electrode materials which are considered promising agents to increase energy density by 50 percent. The analysis revealed that at a high potential state, electrons originating from oxygen were active during charging.
Electrons that originated from manganese were observed to be active during the discharge reaction.
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