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Optical imaging sensor maps electrode activity distribution and OER kinetics in redox flow batteries
The research group led by Professor He Yonghong and Associate Professor Liu Le at Tsinghua SIGS published an article in Nature Communications on November 21, 2019. The paper, titled “In situ mapping of activity distribution and oxygen evolution reaction in vanadium flow batteries” proposed an unprecedented optical imaging method to map electrode activity distribution and bubble kinetics for the onset oxygen evolution potential determination, and shed light on the local electrochemical reaction processes within redox flow batteries.
In the field of large-scale renewable energy storage technology, redox flow batteries are deserving attention for its reliable and sustainable power supply. Vanadium redox flow batteries (VFB), in particular, exhibit promising prospects for industrialization with its long cycle life, scalability, and environmentally-friendly feature. However, conventional methods to evaluate electrochemical performance can only provide the average information of the whole cell. These evaluation methods are unable to factor in spatial distribution differences and reaction kinetics that is also vital to the energy efficiency, charge-discharge capacity, polarization of the electrode.
The research group developed a total internal reflection imaging (TIRi) sensor to map local current distribution of the electrode in a vanadium redox flow battery, enabling mapping of the activity and reversibility distribution. In long term cyclic voltammetry, the bubble kinetics from oxygen evolution reaction (OER) with periodic fluctuation is consistent with the cyclic voltammetry curve, enabling the onset oxygen evolution/reduction potential determination. Higher activity and irreversibility distribution of the electrode is found in favor of the oxygen evolution reaction. This sensor has potential to detect in situ electrochemical reactions in flow batteries, water splitting, electrocatalysis, electrochemical corrosion, and acts as an important tool in improving the overall performance of electrochemical systems.
Activity distribution mapping and bubble kinetics of oxygen evolution reaction in vanadium flow batteries by an optical imaging sensor system.
This work was completed by Ph.D. student Ma Kaijie from Department of Physics, Tsinghua University, together with the guidance and collaboration of Professor He Yonghong, Associate Professor Liu Le, Master student Zhang Yunong, Associate Professor Xi Jingyu, Professor Qiu Xinping and Associate Professor Guan Tian. It was supported by the National Natural Science Foundation of China, Natural Science Foundation of Guangdong Province, and Science and Technology Research Program of Shenzhen City.
Article by Ma Kaijie
Edited by Karen Lee