Fast operando X-ray tomographic microscopy improves polymer electrolyte fuel cells

Operando XTM results of modified fuel cell microporous layer.
Introducing larger pores in the micro-porous layer (MPL) reduces the liquid saturation in the cathode gas diffusion layer by 15 % and improves cell performance by 6 %. Reproduced from Nagai et al., J. Power Sources, 435, 226809 (2019) with permissions of Elsevier.

Polymer electrolyte fuel cells (PEFC) are a key technology for the decarbonization of automotive mobility. To achieve broad market acceptance, still a cost reduction of PEFC systems and operation at higher power densities is required. At high power densities the effective removal of the product water through the porous transport layers in the fuel cell is crucial.

The developments in operando X-ray tomographic microscopy of fuel cells at PSI have established this technique for obtaining incomparable insights into the water transport processes within the opaque porous transport layers of PEFCs. In collaboration with Toyota, it could be shown how modified gas diffusion layer (GDL) reduce the liquid water saturation in the GDL and explain the improved cell performance of the new material. The addition of micrometer sized pores to the microporous layer (MPL), that is sandwiched between the catalyst and gas diffusion layer, results in faster drainage of the product water at even lower GDL saturation.

In collaboration with the TOMCAT beamline, improved instrumentation was realized which is capable to realize sub-second tomography of PEFCs with scan times as short as 0.1 s. This will allow for insights into even more dynamic water transport processes that occur during transient fuel cell operation in fuel cell electric vehicles.

Dr. Jens Eller
Position: Scientist in Fuel Cell Systems and Diagnostics Group
Address: Paul Scherrer Institute PSI, OLGA/113, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
Telephone:0041 56 310 2396

Original Publications:
Improving water management in fuel cells through microporous layer modifications: Fast operando tomographic imaging of liquid water
Authors: Yasutaka Nagai, Jens Eller, Tatsuya Hatanaka, Satoshi Yamaguchi, Satoru Kato, Akihiko Kato, Federica Marone, Hong Xu, Felix N. Büchi

Title: High-numerical-aperture macroscope optics for time-resolved experiments
Authors: Minna Bührer, Marco Stampanoni, Xavier Rochet, Felix Büchi, Jens Eller, Federica Marone


Acknowledgement to:
Swiss National Foundation (SNF) (grant No. 200021_166064)