Formulation of carbon black-ionomer dispersions for thin film formation in fuel cells--颗粒学报PARTICUOLOGY

Hoffmann, E., Zhang, S., Thoma, M., Damm, C., & Peukert, W. (2019). Formulation of carbon black-ionomer dispersions for thin film formation in fuel cells. Particuology, 44, 7-21. https://doi.org/10.1016/j.partic.2018.08.001

Formulation of carbon black-ionomer dispersions for thin film formation in fuel cells

Eva Hoffmann, Su Zhang, Martin Thoma, Cornelia Damm, Wolfgang Peukert ^*

Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, D-91058 Erlangen, Germany

10.1016/j.partic.2018.08.001

Volume 44, June 2019, Pages 7-21

Received 27 March 2018, Revised 6 July 2018, Accepted 9 August 2018, Available online 8 January 2019, Version of Record 30 April 2019.

E-mail: wolfgang.peukert@fau.de

Highlights

• Higher suspension viscosities were observed for higher-branched carbon blacks.

• Larger porosity and less cracking for layers with higher-branched carbon blacks.

• Addition of ionomer improves the colloidal stability of carbon black particles.

• Addition of ionomer reduces film cracking and leads to thinner layers.

Abstract

The performance of proton exchange membrane fuel cells (PEMFC) is strongly determined by the structure and composition of the electrode layer. The interactions between the ionomer, carbon black particles, and solvent affect the suspension properties and thus the layer morphology. We analyze the effect of the ionomer-to-carbon (I/C) weight ratio for two different types of carbon black on the suspension and layer characteristics. Highly branched carbon blacks with a high surface area tend to form less cracked layers. As less branched carbons can pack together more closely, a smaller pore size results in a larger capillary pressure during drying and thus more cracks. The added ionomer adsorbs on the carbon particles and improves the colloidal stability of the carbon black particles. The carbon black aggregates are thus smaller, resulting in closer packing and thinner layers. Moreover, the addition of the ionomer increases the critical coating thickness (CCT) of the layers because drying stresses are dissipated by the deformation of the ionomer, preventing crack formation. An optimum I/C weight ratio is identified for optimal layer formation and minimized crack formation.

Graphical abstract

Keywords

Perfluorosulfonic acid (PFSA) ionomer; Carbon black; Layer formation; Cracking; Porosity

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