Development of Novel Hydrophobic Gas Diffusion Layer for High-Pressure Water Electrolysis using Water-Absorbing Porous Electrolyte

Significance 

Hydrogen gas production can be used to produce electric power that will ensure a reduction in the overreliance in the fossil fuels, whose use being the major pollution cause. Water electrolysis is one of the methods for producing hydrogen gas, enabling its conversion to electrical power by fuel cells. However, higher performing water electrolysis cells have been developed to improve the efficiency of the existing methods. For example, polymer electrolyte water electrolysis (PEWE) comprises of dense polymer electrolyte, the gas diffusion layer and the electrocatalyst layer that ensures supplying water to the electrolyte layer for the electrolysis process.

However, just like PEWE, other hydrogen gas production methods also experience several limitations such as dehydration of the electrolyte layer, poor stability at higher temperatures and decomposition of the carbon supports at the electrodes. Electrolysis cells based on water-absorbing porous electrolyte have the potential of overcoming such limitations. The cell constitutes a hydrophobic gas diffusion layer (GDL), hydrophilic porous electrolyte and electrocatalyst layer. This ensures continuous water supply hence preventing dehydration during electrolysis, controlled pressure for production of pressurized hydrogen gas and reduction of the overvoltage concentration at the electrode.

Despite the cells showing significant improvements in hydrogen gas production, they are expensive to construct and difficult to achieve in complicated cell designs. Therefore, development of new hydrophobic GDLs is capable of achieving the full potential of water-absorbing porous electrolyte electrolysis cells such as gas permeability, high water support force and excellent electron conductivity.

Kyushu University scientists (Dr. Yuki Terayama, Dr. Yoshitsugu Sone, Dr. Masamichi Nishihara, Dr. Stephen M. Lyth) and led by Professor Hiroshige Matsumoto developed a bespoke gas diffusion layer constituting acetylene black (AB) and polytetrafluoroethylene (PTFE) composite films for application in water-absorbing porous electrolyte electrolysis cell. This was in a bid to examine the characteristics of the cell such as water support force, gas permeability and electrical resistance. High-performance uniform AB/PTFE slurry was prepared by ball-milling and transfer method which also aided the covering of the film. Also, the various condition favoring fabrication and composition of GDL was determined. The research work is published in the journal, International Journal of Hydrogen Energy.

The group of authors obtained AB/PTFE optimal composition of 1/2.5 from the evaluated weight ratios by testing the electrical resistance, and gas permeability. As a result, excellent performances such as low electrical resistance, preferable gas permeability, and water support force were achieved. Ball-milling and transfer method enabled the realization of uniform AB/PTFE slurry and covering the films thereby ensuring no crack development on the coated micro-porous layer.

According to the authors, fabrication of an optimized gas diffusion layer was also useful for the excellent performance of the designed cell. For instance, it prevented water injection through the electrolyte layer thereby acting as a gas-permeation layer for effective hydrogen gas generation during the electrolysis process. However, the present system still experiences the problem of limited hydrophobicity resulting in low hydrogen evolution rate and significantly high voltages. The former was about 70% while the latter was about 1.97 when compared to the theoretical values. Thus, the authors attribute future studies towards improving the hydrophobicity of these water-absorbing porous electrolyte electrolysis systems.

 

Development of Novel Hydrophobic Gas Diffusion Layer for High-Pressure Water Electrolysis using Water-Absorbing Porous Electrolyte. Advances in Engineering

 

About the author

Hiroshige Matsumoto received the B. S., M. S., and Ph. D. in Faculty of Engineering from The University of Tokyo, Japan, in 1991, 1993, and 1996, respectively. In 1996, he joined the Faculty of engineering, Nagoya University, Japan. From 1998 to 2002, he was an Assistant Professor in the division of Engineering, Nagoya University. From 2003 to 2005, he was as Assistant Professor in the Institute of Multidisciplinary Research for Advanced Materials of Tohoku University, Japan. From 2004 to 2009, he was an Associate Professor in Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Japan. From 2010 to 2012, he has been a Professor in the INAMORI Frontier Research Center, Kyushu University, Japan.

Since 2013, he has been a Professor in the International Institute for Carbon -Neutral Energy Research (WPI-I2CNER), Kyushu University, Japan. His research interest includes Solid Ionics, Steam Electrolysis, Water Electrolysis, Electrochemistry, and Inorganic Material. Dr. Matsumoto is a member of the Solid State Ionics Society of Japan and the Electrochemical Society of Japan.

About the author

Yoshitsugu Sone graduated from Kyoto University, Japan, in 1991, and received the Ph. D. in Faculty of Engineering from the Graduate School of the University of Tokyo, Japan, in 1996. In 1996, he joined the National Space Development Agency of Japan (NASDA) and has been an Associate Professor of the Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA) since 2003.

His research interest is the space energy management including space battery, fuel cell, and regenerative fuel cell as well as the CO2 reduction reaction for the control of the closed environment like space station. Dr. Sone is the member of the Electrochemical Society of Japan.

About the author

Masamichi Nishihara received the B. S., M. S., and Ph. D. Faculty of Engineering from Kumamoto University, Japan, in 1998, 2000, and 2003, respectively. From 2003 to 2005, he joined Prof. Stefan Matile group in University of Geneva, Switzerland as a post doc. In 2005, he joined Dr. Masayuki Yokoyama’s group in Kanagawa Academy of Science and Technology, Japan as a researcher. From 2009 to 2011, he was a research assistant professor of Prof. Atsushi Takahara group in Institute for Materials Chemistry and Engineering, Kyushu University. From 2011, he joined Prof Kazunari Sasaki group in Kyushu University and worked as an assistant professor (2011-2016), an associate professor (2016-).

His research interests are polymer electrolytes and polymer composites for fuel cells and water electrolyzer, functional polymers for drug delivery system. He received a poster award of 8th ECNP International Conference on Nanostructured Polymers and Nanocomposites 2014 (Dresden, Germany).

About the author

Stephen M. Lyth studied Physics as an undergraduate at Durham University in the UK, then obtained a PhD in Electronic Engineering from the University of Surrey. In 2008, he moved to Japan as a postdoc at Tokyo Institute of Technology. In 2011, he moved to Kyushu University as a WPI Assistant Professor at the International Institute for Carbon-Neutral Energy Research (I2CNER) and was promoted to WPI Associate Professor in 2015. In 2017, he became Associate Professor at the newly-formed Kyushu University Platform of Carbon-Neutral Energy Research (Q-PIT). He is also Visiting Professor at the University of Sheffield in the UK.

His interests are in lowering the cost of new energy technologies to make them available to everybody. He has written over 60 papers on carbon materials, edited a book on Hydrogen Energy Engineering, and given talks at over 70 international conferences.

About the author

Yuki Terayama received the B. S., M. S., and Ph. D. degrees in Department of Applied Chemistry, Faculty of Engineering from Kyushu University, Japan, in 2006, 2008, and 2011, respectively. After he got his Ph. D., he worked at Asahi Intecc Co., Ltd., Osaka, Japan as a Medical Company from 2011 to 2014. From 2014 to 2018, he was a Post-doctoral Fellow in the International Institute for Carbon -Neutral Energy Research, Kyushu University, Japan. Since 2018, he has been a Research Assistant Professor in Department of Chemical Engineering, Faculty of Engineering, Kyushu University, Japan.

His research interests are in development of water electrolysis cell, CO2 absorption/desorption process module, and medical device (catheter or guide wire). He is also working on hydrophilic or hydrophobic material, polymer chemistry and physics, electrochemistry, and surface science in general.

 

Reference

Terayama, Y., Haji, T., Furukawa, S., Nomura, M., Nishihara, M., & Lyth, S. et al. (2018). Carbon black / PTFE composite hydrophobic gas diffusion layers for a water-absorbing porous electrolyte electrolysis cell. International Journal of Hydrogen Energy43(4), 2018-2025.

Go To International Journal of Hydrogen Energy

Check Also

Continuous emulsion copolymerization processes at mild conditions in a 3D-printed tubular bended reactor - Advanced Engineering

Continuous emulsion copolymerization processes at mild conditions in a 3D-printed tubular bended reactor