University of Cambridge
Emerging Electrochemical Technologies: Advanced Engineering Design
Abstract
dc:description.abstractThis thesis investigates emerging electrochemical technologies. Central to the research are two specific electrochemical systems: (a) non-Newtonian fluid dynamics in electrochemical sensors and reactors, that are well poised to improve production methods in the chemical industry, and (b) gas diffusion electrolysers used in various emerging industrial applications that deal with gaseous reactants. The study uses a combination of analytical solutions and numerical simulations to shed light on the underlying physical and chemical processes that govern these systems. Limiting current expressions for power-law fluids are derived for the rotating disk and channel electrodes. Practical guidelines on when it is appropriate to use those expressions are given, as well as guidelines on how reactor or sensor dimensions can be designed so that the derived limiting current equations are valid. The results demonstrate significant variations in electrochemical behaviour when compared to Newtonian fluids, meaning great care should be taken when transferring knowledge and standard operating procedures from learnings of those. Electrochemical impedance spectroscopy is introduced as a tool to research mass transport in non-Newtonian fluids, in addition to it being invaluable in settings where non-destructive and real-time monitoring of electrochemical systems is required. The Warburg impedance of a channel electrode systems is derived and versatile ways of using the results are discussed. In examining gas diffusion electrodes, the thesis identifies key factors that influence their efficiency and functionality, with focus on potential and current density drops within the electrode. A simple dimensionless factor is derived, that quantifies potential or current density drops within a gas diffusion electrode between current collectors. The factor can be used to estimate a maximum distance between current collectors, given a desired material and current density. An optimal width of the current collectors needed to minimise the potential drop that arises between the gas diffusion electrode and current collector is derived. It depends only on the thickness and conductance of the gas diffusion electrode, not the current density of the cell. Overall, the findings contribute to a better understanding of complex electrochemical systems and support the development of more efficient, sustainable technologies for chemical production. The work provides practical recommendations for lab-scale and industrial applications in electrochemistry.
Degree
thesis:*- Name dc:type.qualificationname
- Doctor of Philosophy (PhD)
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Cambridge
- Year dc:date.issued
- 2024
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Dagbjartsdóttir, Freyja Björk
- Advisor dc:contributor.advisor
-
- Fisher, Adrian
Subjects
dc:subject × 8Rights
dc:rightsIdentifiers
dc:identifier.*- DOI dc:identifier.doi
- https://doi.org/10.17863/CAM.117243
- OAI identifier oai:identifier
- oai:www.repository.cam.ac.uk:1810/382437