Membranes and Electrochemical Cells

Our mission is to create innovation in the area of polymer electrolyte materials for electrochemical applications, notably fuel cells, electrolysis cells, and redox flow cells. We aim to prepare polymers with desired functionalities for the respective application and operating conditions, using commercially available and low-cost materials (base films, monomers and additives) and industrially viable processing techniques. Furthermore, we develop dedicated diagnostic methods to study limitations in cell performance and aging of materials and components.
 

Our synthetic strategy is based on the preparation and functionalization of polymer films via radiation-induced grafting to obtain membranes containing ionic sites. Activation of the base polymer film can be done using an electron beam (performed externally). For surface grafting, the film is activated in a plasma chamber. Activated films are stored in a fridge at a temperature of -80°C. For the grafting reaction, a wide range of vinyl monomers amenable to radical polymerization can be used, such as styrenes and acrylics. Post-treatment of grafted films may involve various chemical processing steps, such as sulfonation to introduce proton exchange sites.

The laboratory has a wide range of characterization methods for ex situ characterization of starting materials, intermediates and membranes: infrared and Raman spectroscopy for composition analysis, SEM-EDX, XPS, DSC/TGA, tensile testing machine, etc. The conductivity of membranes is measured using ac impedance spectroscopy (in-plane or through-plane). In addition, we have a well-equiped fuel cell test infrastructure with test benches for single cells up to stacks for 30 kW power output. We aim to understand component and cell performance characteristics and limitations thereof, in particular aging phenomena of membranes and electrodes under application-relevant or accelerated test conditions.

Water electrolysis plays a key role in future energy scenarios (power-to-gas). We study materials aspects of polymer electrolyte water electrolyzers with a few to increasing performance and efficiency and investigate mechanican and chemical aging phenomena of key cell components. Two custom-built test benches for cells of 25 cm2 active area can be operated up to a pressure of 20 bar. We can measure impedance spectra and monitor the purity of gases (in particular H₂ contamination in O₂) continuously.

Current group members:

• Lorenz Gubler, Head
• Tamás Németh, Postdoctoral Research Fellow
• Davide Masiello, Postdoctoral Research Fellow
• Jamie Duburg, PhD Student
• Zheyu Zhang, PhD Student
• Zongyi Han, PhD Student
• Yingying Yu, ETH Semester Project Student
• Masis Sirim, Master Thesis project, Johannes Gutenberg-University, Mainz (Germany)

- Postdoctoral Fellow: Antioxidant strategies for anion exchange membranes

Furthermore, we have regular openings for student's projects in different areas: fuel cells, electrolyzers, redox flow cells on topics ranging from materials synthesis and characterization to test system design and implementation.

A complete publication list can be found on Scopus.