Innovations in hydrocarbon fuel cell membranes

Michael D. GuiveProfessor Michael D. Guiver, State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, China

Abstract

During the last two decades, there has been much interest in hydrocarbon-based proton exchange membranes (PEM) to replace commercial membranes like perfluorosulfonic acid commercial membranes (Nafion) in fuel cells (FC) and other electrochemical applications. The reasons for this are cost, and the potential for higher temperature operation at reduced relative humidity (RH). However, their conductivity and chemical stability, especially during in situ FC operation, often fall short of expectations. In the last several years, research focus has turned to anion exchange membranes (AEM), because expensive platinum group catalysts can be avoided, but alkali stability and sensitivity to atmospheric CO2 are also big challenges. With strongly renewed interest in clean energy and fuel cell adoption [1], our research is focused on exploring efficient ion conduction in hydrocarbon-based PEMs and AEMs through the construction of membrane through-plane channels, i.e., by shortening the distance between anode and cathode for ion transport through purpose-built pathways. We achieve this using paramagnetic polymers which align in a magnetic field [2‒4]. The PEM channels have ferrocyanide linked with phosphotungstic acid, which becomes paramagnetic under a strong field [2,3]. The channels exhibit microporosity, enabling them to retain water at elevated temperatures, allowing good PEMFC performance under low humidity and elevated temperature. We observed that the membranes exhibited unexpected and unusually good free radical oxidative stability as well as stable PEMFC performance. This derives from ferrocyanide units incorporated into 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 both proton conductors in their own right [5], and to stabilize membranes through ferrocyanide-ferricyanide redox couples [6]. We have applied this to both perfluorocarbon and hydrocarbon-based PEMs, to enhance oxidative stability under low relative humidity. In more recent work, we designed AEMs with ferrocenium cations [4], providing aligned hydroxide-conducting channels. Under the conditions used, a mixed valence state is formed, which imparts unusually high stability. Our ongoing work explores other alignment processes.

  1. 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, N. P. Brandon, Y. Yin, M. D. Guiver, Nature, 595, 361–369 (2021)
  2. 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, M. D. Guiver, Nat. Commun., 10, 842 (2019).
  3. Oriented proton-conductive nano-sponge-facilitated polymer electrolyte membranes, X. Liu, J. Zhang, C. Zheng, J. Xue, T. Huang, Y. Yin, Y. Qin, K. Jiao, Q. Du, M. D. Guiver, Energy Environ. Sci. 13, 297−309 (2020).
  4. Magnetic-field-oriented mixed-valence-stabilized ferrocenium anion exchange membrane, X. Liu, J. Xue, M. Li, C. Zheng, J. Zhang, Y. Qin, Y. Yin, D. R. Dekel, M. D. Guiver. Nat. Energy (2022). https://doi.org/10.1038/s41560-022-00978-y
  5. A paradigm shift for a new class of proton exchange membranes with ferrocyanide proton-conducting groups providing enhanced oxidative stability, X. Zhang, Y. Li, X. Liu, J. Zhang, Y. Yin, M. D. Guiver, J. Membr. Sci., 616, 118536 (2020).
  6. Durability enhancement of proton exchange membrane fuel cells by ferrocyanide or ferricyanide additives, X. Liu, Y. Li, M. Li, J. Zhang, Y. Qin, Y. Yin, M. D. Guiver, J. Membr. Sci. 629, 119282 (2021).

Biography

Michael D. Guiver was brought up in England, and he obtained his BSc in chemistry from London University. He moved to Canada, and obtained his M.Sc. and Ph.D. from Carleton University. He joined the National Research Council Canada (NRC) in 1987, working on novel membrane materials. He spent most of his career at NRC working mostly on membranes for gas separation and fuel cells. He left NRC in 2014 as a Principal Research Officer. He served twelve years as an Editor for the Journal of Membrane Science (2009‒2020). He is now the Field Chief Editor for Frontiers in Membrane Science and Technology, a recently launched journal. He has served and is currently on several journal Editorial and Advisory Boards. He has been on the Advisory Board for the Barrer Centre, Imperial College, since October 2016. He is a Fellow of the Royal Society of Chemistry and ACS Poly division. In 2009-2013, he was appointed as a visiting professor at the Department of Energy Engineering, Hanyang University, Seoul, Korea, under the World Class University Korean government-funded program, and spent four semesters there. In September 2014, he left Canada and relocated to the State Key Laboratory of Engines, Tianjin University, China in a full-time position. He has published about 275 papers including book chapters and is an inventor on over 20 patents. His primary expertise is in polymer chemistry, architecture and ordered structures and his research interests are in polymeric 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 is also investigating the stabilization of hydrocarbon-based ionomer membranes, allowing their practical use. His research activities in polymeric membranes span forty years.

Zoom webinar link: https://imperial-ac-uk.zoom.us/j/99807052809?pwd=NDJHSHYyUjZ3Nm9ya1hBcDlPU1d1QT09
Webinar ID: 998 0705 2809

Passcode: Pemfc@2022

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