Seminar - Influence of relative humidity on the structure and electrochemical performance of LiFeSO4F electrodes for Li-ion batteries by Prof. Guohua CHEN
日期：2016 年 02 月 26 日 ( 星期五)
Time：11:00 am – 12:00 pm
The recently reported tavorite-type LiFeSO4F cathode material, which shows a redox potential of 3.6 V and a practical capacity of ~130 mA h g-1 without the need for sophisticated carbon coating or particle downsizing, stands presently as a serious contender to LiFePO4, one of the popular cathode materials for lithium ion batteries. However, its synthesis is still not routinely reproducible. In this talk, a direct explanation on both LiFeSO4F aging stability and its electrochemical performances will be given by showing the strong effect of the room temperature relative humidity. The complete degradation of tavorite-type LiFeSO4F into FeSO4•nH2O (n=1, 4, 7) and LiF is demonstrated in environments with relative humidity values greater than 62%. The feasibility of triggering in situ formation of a F--free (Li)FeSO4OH phase is also shown within the cell. It provides a foundation for achieving the consistent production and handling of LiFeSO4F electrodes in view of large-scale manufacturing. This moisture sensitivity issue, which can be mitigated by surface treatments, is inherent to sulfate-based electrode materials. It is important for the battery community to be aware of.
Professor Guohua CHEN is now the Head and Professor, Department of Chemical and Biomolecular Engineering, the Hong Kong University of Science and Technology. He was the Chairman, Chemical Discipline, Hong Kong Institution of Engineers during 2009 and 2012. He is serving as the President, Asian Pacific Confederation of Chemical Engineering. He is an Adjunct Professor of Dalian University of Technology and Changjiang Scholar (Chair), Ministry of Education, China (2011-2013). He is a non-executive Director, FDG Kinetics. He is an Associate Editor, Chinese Journal of Chemical Engineering. He has been an Editor of Separation and Purification Technology since 2006. Professor Chen’s research interests include electrochemical technologies for wastewater treatment, drying of solids, electrochemical energy storage, green products and processing technologies. He has published over 235 journal papers with over 13650 Google citations and H index being 63. He edited 3 books, was granted two US patents and four China patents. He received the Certificate of Excellence in 2007 from the World Forum of Crystallization, Filtration and Drying. He was one of the three recipients of the inaugural Research Excellence Award in 2011 from the School of Engineering, the Hong Kong University of Science and Technology. He is a Fellow of HKIE, and a Fellow of American Institute of Chemical Engineers.