Date of Completion

12-16-2016

Embargo Period

12-15-2017

Keywords

fuel cell, contamination and mitigation, wettability, Wilhelmy plate method, membrane electrode assembly (MEA)

Major Advisor

Ugur Pasaogullari

Associate Advisor

Prabhakar Singh

Associate Advisor

Michael Pettes

Associate Advisor

Brice Cassenti

Associate Advisor

Trent Molter

Field of Study

Mechanical Engineering

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Fuel cells have received significant attention as a promising candidate for efficient and emission-free power in automotive, stationary, and portable applications. This work is focused on sophisticated schemes for surface wettability impact on fuel cell performance are required by using proper wettability characteristics for the fuel cell components.

Foreign cations are shown to cause mass transport losses, in particular due to wettability changes in the gas diffusion media (GDM) and have a major impact on the durability and the performance of polymer electrolyte fuel cell (PEFC). The effects of cationic impurities on fuel cell system performance, especially on the water management has been studied by employing in-situ and ex-situ contamination methods. Changes in the wettability of the GDM surface following the in-situ contamination injection were quantified using a force tensiometer employing the Wilhelmy plate method. Identification and mitigation of adverse effects of cationic airborne contaminants on fuel cell system performance and durability has been studied and effective recovery methods are proposed.

A new membrane electrode assembly (MEA) concept is introduced, where the carbon paper substrate is eliminated and the entire GDM consists of only the micro-porous layer (MPL) directly applied on the catalyst coated membrane (CCM). Spray deposition with a heated plate is used to fabricate the MPL directly onto both sides of the catalyst coated membrane (CCM), simplifying the fabrication and assembly, and results in a more robust interface between the MPL and the catalyst layer. The new MEA structure provides superior pathways for gas transport and water evacuation, reduces flooding at high current densities, and results in a stable voltage at higher current densities by improving mass transport.

Wilhelmy balance in a force tensiometer was successfully applied to study the wetting property of an electrode matrix in the electrolyte of molten carbonate fuel cells (MCFCs). MCFCs are high-temperature fuel cells that use a molten carbonate salt mixture as an electrolyte integrated in a porous ceramic matrix. The performance of MCFC highly depends on the surface tension of the molten carbonate and the contact angle with the electrolyte matrix in the solution. A new formulation based on the Wilhelmy force balance equation is developed to determine the contact angle for samples with irregular shapes.

Available for download on Friday, December 15, 2017

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