Three-dimensional microstructure analysis of a polymer electrolyte membrane water electrolyzer anode

authored by

Friedemann Hegge, Riko Moroni, Patrick Trinke, Boris Bensmann, Richard Hanke-Rauschenbach, Simon Thiele, Severin Vierrath

Abstract

The anode catalyst layer of a PEM water electrolyzer is reconstructed using a combination of FIB-SEM tomography and ionomer modeling. The pore space is infiltrated with silicone, enabling good discrimination between pores and IrRuOx catalyst material, while the ionomer cannot be imaged. The reconstructed volume of 29 μm × 24 μm x 7 μm contains catalyst particles with a median size of 0.5 μm and has a porosity of 55%. By modeling different ionomer contents inside the pore space, the impact on microstructural and transport parameters is investigated. At an ionomer content of 40-50% of the pore volume, all transport parameters are in a reasonable range, confirming experimental results from literature. At an ionomer content of 48% the catalyst layer has a porosity of 29%, a median pore size of 0.94 μm, a permeability of the pore space of 1.8mD and a mean ionomer film thickness of 0.4μm. The tortuosities of the ionomer and the pore space are calculated to 3.5 and 6.7 at the corresponding phase fractions of 26% and 29% respectively. The electrochemically active surface area estimated from the tomography (1.0m²g⁻¹) is considerably lower than literature values, indicating a roughness below FIB-SEM resolution.

Organisation(s)

Institute of Electric Power Systems
Section Electrical Energy Storage Systems

External Organisation(s)

University of Freiburg
Forschungszentrum Jülich
Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU Erlangen-Nürnberg)
FIT - Freiburg Center for Interactive Materials and Bioinspired Technologies
Hahn Schickard Society for Applied Research

Type

Article

Journal

Journal of Power Sources

Volume

393

Pages

62-66

No. of pages

5

ISSN

0378-7753

Publication date

31.07.2018

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Renewable Energy, Sustainability and the Environment, Energy Engineering and Power Technology, Physical and Theoretical Chemistry, Electrical and Electronic Engineering

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1016/j.jpowsour.2018.04.089 (Access: Closed)