Investigation of Overpotential Distributions in a Solid Oxide Electrolysis Cell using Experimental and Modeling Approaches
Author
Pasik, Emilia
Term
4. term
Education
Publication year
2025
Submitted on
2025-05-28
Pages
93
Abstract
This thesis examines how overpotentials are distributed in a solid oxide cell using both experiments and modeling. A solid oxide cell is a high-temperature electrochemical device. Overpotentials are the extra voltage beyond the ideal value caused by losses in reactions and transport. We employ a 3D finite element model in COMSOL Multiphysics to simulate electrochemical, thermal, and transport phenomena. Experimental validation includes I–V curve measurements, electrochemical impedance spectroscopy, and gas composition analysis by mass spectrometry. The model agrees well with the experiments and captures how overpotentials vary across the cell. Electrolysis at the thermoneutral voltage (where heat generation and consumption balance so temperature can remain steady) is analyzed in detail to evaluate overpotentials and local heat sources and sinks. The results underscore the importance of spatially resolved modeling for understanding and optimizing solid oxide cell performance. The model enables detailed analysis of current density distribution, local overpotential behavior, and heat source contributions. Combined with the experimental data, it is a useful tool for assessing operating strategies and guiding design improvements in high-temperature electrolysis systems.
Denne afhandling undersøger, hvordan overpotentialer fordeler sig i en fastoxid-celle ved hjælp af både forsøg og modellering. En fastoxid-celle er en højtemperatur elektrokemisk enhed. Overpotentialer er den ekstra spænding ud over den ideelle, som opstår på grund af tab i reaktioner og transport. Vi bruger en 3D finit element-model i COMSOL Multiphysics til at simulere elektrokemiske, termiske og transportmæssige fænomener. Modellen valideres eksperimentelt med I/U-kurver, elektrokemisk impedansspektroskopi og gassammensætningsmålinger med massespektrometri. Modellen stemmer godt overens med data og kan beskrive, hvordan overpotentialer varierer hen over cellen. Elektrolyse ved den termoneutrale spænding (hvor varmeproduktion og -forbrug balancerer, så temperaturen i princippet er stabil) analyseres detaljeret for at vurdere overpotentialer og lokale varme-kilder og -dræn. Resultaterne fremhæver, at rumligt opløst modellering er vigtig for at forstå og optimere fastoxid-cellens ydeevne. Modellen gør det muligt at analysere fordelingen af strømtæthed, lokal overpotentiale-adfærd og bidrag fra varmekilder. Sammen med de eksperimentelle data giver den et nyttigt værktøj til at vurdere driftsstrategier og vejlede designforbedringer i højtemperaturelektrolysesystemer.
[This apstract has been rewritten with the help of AI based on the project's original abstract]
Keywords