Microscopic and spectroscopic characterization of fuel cell catalyst layer materials and interfaces

Polymer electrolyte membrane fuel cells (PEMFCs) are a central technology for the decarbonization of the heavy-duty transportation sector and of industrial processes. This thesis is focused on detailed electron microscopy and x-ray spectroscopy characterization of composition and morphology of surfaces and interfaces in PEMFCs with the goal of building structure-property-processing relationships to improve current understanding of their influence on performance. Chapter 1 provides an overview of PEM fuel cell components and materials and describes the motivation for this thesis. Chapter 2 briefly introduces characterization methods used in this work to study fuel cell electrode materials and membrane electrode assembly interfaces. Characterization methods include scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy. This chapter also describes several case studies that utilized the electron microscopy to address various research questions, including the investigation of the role of defects at the catalyst layer/membrane interface, the degradation of alkaline fuel cell materials, and the investigation of catalyst ionomer distribution and catalyst ionomer interfaces within the catalyst layer. Chapter 3 investigates the properties of a series of roll-to-roll coated gas diffusion electrodes comparing them to spray coated electrodes. Cathode catalyst layer surface properties, including surface roughness and surface texture features, as well as elemental composition (ionomer content relative to Pt) at the top surface, subsurface, and in the bulk were correlated to fuel cell performance. Chapter 4 discusses spray coated gas diffusion electrodes fabricated with two types of gas diffusion media and with various loadings of additional ionomer overlayer. This work advances the fundamental studies and provides important feedback to accelerate large-scale manufacturability and commercialization of fuel cell technologies. Methodologies developed in this thesis are applicable to other PEM systems such as alkaline fuel cells, H2O and CO2 electrolyzers.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2022

Author dc:creator

• Medina, Samantha

Advisor dc:contributor.advisor

• Pylypenko, Svitlana

Committee members dc:contributor.committeemember

• Richards, Ryan
• Diercks, David R.
• Neyerlin, Kenneth C.
• Porter, Jason M.

• catalyst layer-membrane interface
• GDE interfaces
• GDE surface composition
• GDE surface morphology
• R2R-coated GDEs
• structure-property-processing-performance relationship

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 9329

OAI identifier oai:identifier

oai:repository.mines.edu:11124/15412