Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Materials Science and Engineering

Committee Chair/Advisor

Jianhua Tong

Committee Member

Kyle S. Brinkman

Committee Member

Fei Peng

Committee Member

Luiz Jacobsohn

Committee Member

Ming Yang

Abstract

Protonic ceramic fuel cells (PCFCs) have received increasing attention as electrochemical energy conversion devices for intermediate temperature operation. However, translating promising materials into high-performance single cells remains challenging because cell performance depends strongly on electrolyte density, layer quality, interfacial contact and gas transport in the multilayer structure. Therefore, a better understanding of the relationship between fabrication, microstructure and electrochemical behavior is needed to further improve PCFC performance and durability.

The first part of this dissertation investigates the effect of NiO addition sequence on BaCe0.4Zr0.4Y0.1Yb0.1O3-δ (BCZYYb4411) electrolyte ceramics. Different NiO addition routes were studied to understand how introducing a sintering aid during powder calcination and pellet sintering affects phase formation, densification, microstructure and conductivity. A dual-step NiO addition strategy was found to promote perovskite phase formation, improve electrolyte densification and produce a larger-grained microstructure with higher total conductivity.

Following optimized electrolyte processing, the next step was to translate the BCZYYb4411 electrolyte material into single-cell devices. Tape casting, ultrasonic spray coating and brush painting were combined to prepare the anode support layer, anode functional layer, electrolyte layer and cathode. By controlling slurry formulation, coating conditions, layer thickness and co-firing profile, dense and continuous electrolyte layers with good electrode contact were obtained, and the thickness and quality of each layer were reproducibly controlled by the coating design. The resulting single cells exhibited open-circuit voltages above 1.0 V and good electrochemical performance, demonstrating that the developed workflow is suitable for preparing anode-supported PCFC single cells with thin, dense electrolyte films.

With the reproducible fabrication workflow established, the effect of anode support layer (ASL) porosity on PCFC performance and durability was further investigated. Anode-supported single cells with (porous ASL) and without (dense ASL) pore former were designed and fabricated using the developed workflow to limit variations from the other layers. Compared with the dense ASL cell, the porous ASL cell exhibited an open support structure, a higher peak power density, and much better durability during galvanostatic operation. The DRT analysis of the electrochemical response and post-test microstructure observations suggests that the porous support improved fuel access and facilitated more uniform NiO reduction, thereby enhancing cell performance and stability.

Overall, this dissertation demonstrates that processing and microstructure design are critical for improving the performance and durability of PCFCs. The dual-step NiO addition strategy improved the densification and conductivity of BCZYYb4411 electrolyte ceramics. A reproducible single-cell fabrication workflow was established to control the layer thickness and quality. With this fabrication basis, the porous ASL design further improved fuel transport and NiO reduction behavior, leading to higher cell performance and better long-term stability.

Author ORCID Identifier

https://orcid.org/0009-0000-5702-2954

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Available for download on Tuesday, August 31, 2027

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