Innovations in hydrocarbon fuel cell membranes
Professor Michael D. Guiver, State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, China
Over the past two decades, hydrocarbon-based proton exchange membranes (PEMs) have generated great interest to replace commercial membranes such as commercial perfluorosulfonic acid (Nafion) membranes in fuel cells (FCs) and other electrochemical applications. The reasons for this are cost and the possibility of operation at higher temperatures with reduced relative humidity (RH). However, their conductivity and chemical stability, especially during on the spot FC functioning, often below expectations. In recent years, research has focused on anion exchange membranes (AEMs), because expensive platinum group catalysts can be avoided, but alkali stability and sensitivity to atmospheric CO2 are also great challenges. With renewed interest in clean energy and the adoption of fuel cells , our research focuses on exploring efficient ion conduction in hydrocarbon-based PEMs and AEMs through the construction of membrane channels across the plane, i.e., by shortening the distance between the anode and cathode for transporting ions through specially designed pathways. We achieve this by using paramagnetic polymers that align in a magnetic field [2‒4]. PEM channels have ferrocyanide bound to phosphotungstic acid, which becomes paramagnetic under a strong field [2,3]. The channels exhibit microporosity, allowing them to retain water at high temperatures, enabling good PEMFC performance in low humidity and high temperature conditions. We observed that the membranes exhibited unexpected and exceptionally good free radical oxidative stability as well as stable PEMFC performance. This derives from ferrocyanide units embedded in the PEM structure, which are capable of quenching free radicals by redox reaction. Developing this aspect further, we then explored practical ways to stabilize PEMs by incorporating ferrocyanide, as proton conductors in their own right. and to stabilize the membranes by ferrocyanide-ferricyanide redox couples . We have applied this to perfluorocarbon and hydrocarbon based PEMs, to improve oxidative stability under low relative humidity. In more recent work, we designed AEMs with ferrocenium cations , providing aligned hydroxide-conducting channels. Under the conditions used, a mixed valence state is formed, which confers exceptionally high stability. Our current work explores other alignment processes.
- Designing the Next Generation of Proton Exchange Membrane Fuel Cells, K. Jiao, J. Xuan, Q. Du, Z. Bao, B. Xie, B. Wang, Y. Zhao, L. Fan, H. Wang , Z. Hou, NP Brandon, Y. Yin, MD Guiver, Nature595, 361–369 (2021)
- Magnetic Field Alignment of Stable Proton Conducting Channels in an Electrolyte Membrane, X. Liu, Y. Li, J. Xue, W. Zhu, J. Zhang, Y. Yin, Y. Qin, K. Jiao, Q. Du , B.Cheng, X.Zhuang, J.Li, MD Guiver, Nat. Commune., 10, 842 (2019).
- Polymer electrolyte membranes facilitated by proton-conducting nano-sponges, X. Liu, J. Zhang, C. Zheng, J. Xue, T. Huang, Y. Yin, Y. Qin, K. Jiao, Q. Du, MD guide, Energy Approx. SCI. 13, 297−309 (2020).
- Magnetic field-oriented mixed-valence stabilized ferrocenium anion exchange membrane, X. Liu, J. Xue, M. Li, C. Zheng, J. Zhang, Y. Qin, Y. Yin, DR Dekel, MD Guiver. Nat. Energy (2022). https://doi.org/10.1038/s41560-022-00978-y
- A Paradigm Shift for a New Class of Proton Exchange Membranes with Proton Conducting Ferrocyanide Groups Offering Improved Oxidative Stability, X. Zhang, Y. Li, X. Liu, J. Zhang, Y. Yin, MD Guiver, J. Member. SCI., 616, 118536 (2020).
- Improving the durability of proton exchange membrane fuel cells by ferrocyanide or ferricyanide additives, X. Liu, Y. Li, M. Li, J. Zhang, Y. Qin, Y. Yin, MD Guiver, J. Member. SCI. 629, 119282 (2021).
Michael D. Guiver grew up in England, and earned his BSc in Chemistry from the University of London. He moved to Canada and obtained his M.Sc. and Ph.D. from Carleton University. He joined the National Research Council of Canada (NRC) in 1987, working on new membrane materials. He has spent most of his career at NRC working primarily on membranes for gas separation and fuel cells. He left NRC in 2014 as a Senior Research Officer. He served twelve years as editor for the Journal of Membrane Science (2009‒2020). He is now a field editor for Frontiers of Membrane Science and Technology, a recently launched journal. He has served and is currently a member of several editorial and advisory boards of journals. He has been a member of the Advisory Board of the Barrer Centre, Imperial College, since October 2016. He is a Fellow of the Royal Society of Chemistry and of the ACS Poly Division. From 2009 to 2013, he was appointed as a visiting professor at the Department of Power Engineering, Hanyang University, Seoul, Korea, under the Korean government-funded program at World Class University, and spent four semesters. In September 2014, he left Canada and moved to the State Key Laboratory of Engines at Tianjin University, China in a full-time position. He has published approximately 275 articles, including book chapters, and is the inventor of over 20 patents. His main expertise is in polymer chemistry, architecture and ordered structures and his research interests are in polymer membrane gas separations and ion conducting membranes for fuel cells. He works on microporous polymers, carbon dioxide separation, propylene/propane separation, proton exchange membranes, anion exchange membranes, and also studies the stabilization of hydrocarbon-based ionomer membranes, allowing their use. practice. His research activities on polymeric membranes span forty years.
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