报告题目：Development of the lithium-air battery

报告人：Prof Lee Johnson

报告人单位：诺丁汉大学

时间：2024年6月25日（星期二）上午10：00

地点：弘毅楼四楼中庭报告厅

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Lithium-ion batteries have delivered a revolution in portable electronics and have begun to unlock electrification of the automotive industry. However, intrinsic performance limitations mean that many applications will be out of reach for lithium-ion technology. We must explore alternatives if we are to have any hope of meeting the long-term needs for energy storage. One such alternative is the air-breathing Li-air (O₂) battery; its theoretical specific energy exceeds that of Li-ion. On discharge, lithium is oxidised to lithium-ions at the negative electrode and oxygen is reduced to lithium peroxide at the positive electrode, with the reaction being reversed on charge. Unfortunately many hurdles hinder its realization.

Here we will discuss our advances made in understanding the fundamental science underpinning the lithium-air battery and the impact this has on the technology. Using mediators (molecular redox catalysts) and by redesigning the porous cathode, we have been able to increase O₂transport delivering areal capacities on discharge of more than 20 mAh cm^-2at a rate of 1-2 mA cm^-2. Comparable oxidation mediators to charge Li₂O₂are needed on charge but rates can be limited and they operate at 3.7 V offering poor energy efficiency. We have shown recently that the oxidation of Li₂O₂by redox mediators follows Marcus theory, i.e. an outer sphere election transfer of e^-from Li₂O₂to the Ox molecule. These results indicate strategies to improve the performance of mediators in the cell. The factors limiting the Li₂O₂yield and the source of degradation will be discussed and we will show that¹O₂is not a major antagonist in the cell.While the lithium-air battery has the potential to exceed significantly the specific energy of other rechargeable batteries, it is assumed to be intolerant to H₂O partly due to irreversible formation of LiOH at the positive electrode, rather than the desired Li₂O₂. Thus, to operate in air, the battery is expected to include a gas-handling system to remove unwanted gaseous impurities such as H₂O and CO₂and, unfortunately, this will add significant weight to the system. Here we describe how H₂O impacts the chemistry of the oxygen reduction reaction in the organic solvents used in the lithium-O₂battery and identify the factors that determine when the oxygen reduction reaction switches from Li₂O₂formation to LiOH formation on discharge. We will show the specific reaction that is responsible for LiOH formation in H₂O-containing aprotic lithium-air batteries and demonstrate a H₂O tolerant Li-air cathode (100% relative humidity at 20^oC) which exclusively forms Li₂O₂, the desired discharge product.

个人简介：

Lee Johnson received his PhD in physical chemistry and electrochemistry at the University of Nottingham in 2011. He then joined the research group of Prof Sir P.G. Bruce FRS at the University of Oxford, where he studied the lithium-oxygen battery. In 2017, he was awarded a Nottingham Research Fellowship, University of Nottingham, followed by an EPSRC Fellowship in 2018. In 2019 he was promoted to Associate Professor in the School of Chemistry and then to Professor of Electrochemistry in 2024. His current research interests focus on understanding interfacial reactions, degradation, and charge transfer, in electrochemical energy devices such as electrolysers, lithium-sulfur, lithium-air, Mg and nickel-rich batteries.

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