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Porous Electrode and Nonequilibrium Water Transport Modelling in Polymer Electrolyte Fuel Cells
KTH, Skolan för teknikvetenskap (SCI), Mekanik.
KTH, Skolan för teknikvetenskap (SCI), Mekanik.ORCID-id: 0000-0002-2906-9306
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Abstract [en]

Recent years have seen the appearance of numerous modelling studies of the polymer electrolyte fuel cell. However, in spite of observations in different studies that a model for a cell operating under single-phase conditions must include nonequilibrium water transport and must spatially resolve the porous electrodes in order to capture the behaviour of the cell correctly, there are only very few models in the literature that simultaneously do both. This paper, however, formulates such a model and considers a one-dimensional version of it in a parameter study. In future work, the model will be used to calibrate model parameters against experiments and study the operation of cells in higher dimensions.

Nyckelord [en]
polymer electrolyte fuel cell, modelling, porous electrode, nonequilibrium water transport
Nationell ämneskategori
Oorganisk kemi
Identifikatorer
URN: urn:nbn:se:kth:diva-11050OAI: oai:DiVA.org:kth-11050DiVA, id: diva2:235084
Anmärkning
QC 20101019Tillgänglig från: 2009-09-12 Skapad: 2009-09-12 Senast uppdaterad: 2010-10-19Bibliografiskt granskad
Ingår i avhandling
1. Validated Modelling of Electrochemical Energy Storage Devices
Öppna denna publikation i ny flik eller fönster >>Validated Modelling of Electrochemical Energy Storage Devices
2009 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis aims at formulating and validating models for electrochemical energy storage devices. More specifically, the devices under consideration are lithium ion batteries and polymer electrolyte fuel cells.

A model is formulated to describe an experimental cell setup consisting of a LixNi0.8Co0.15Al0.05O2 composite porous electrode with three porous separators and a reference electrode between a current collector and a pure Li planar electrode. The purpose of the study being the identification of possible degradation mechanisms in the cell, the model contains contact resistances between the electronic conductor and the intercalation particles of the porous electrode and between the current collector and the porous electrode. On the basis of this model formulation, an analytical solution is derived for the impedances between each pair of electrodes in the cell. The impedance formulation is used to analyse experimental data obtained for fresh and aged LixNi0.8Co0.15Al0.05O2 composite porous electrodes. Ageing scenarios are formulated based on experimental observations and related published electrochemical and material characterisation studies. A hybrid genetic optimisation technique is used to simultaneously fit the model to the impedance spectra of the fresh, and subsequently also to the aged, electrode at three states of charge. The parameter fitting results in good representations of the experimental impedance spectra by the fitted ones, with the fitted parameter values comparing well to literature values and supporting the assumed ageing scenario.

Furthermore, a steady state model for a polymer electrolyte fuel cell is studied under idealised conditions. The cell is assumed to be fed with reactant gases at sufficiently high stoichiometric rates to ensure uniform conditions everywhere in the flow fields such that only the physical phenomena in the porous backings, the porous electrodes and the polymer electrolyte membrane need to be considered. Emphasis is put on how spatially resolved porous electrodes and nonequilibrium water transport across the interface between the gas phase and the ionic conductor affect the model results for the performance of the cell. The future use of the model in higher dimensions and necessary steps towards its validation are briefly discussed.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2009. s. vi, 28
Serie
Trita-MEK, ISSN 0348-467X ; 2009:12
Nyckelord
lithium ion battery, polymer electrolyte fuel cell, modelling, model validation, parameter fitting
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
urn:nbn:se:kth:diva-11052 (URN)978-91-7415-423-8 (ISBN)
Presentation
2009-09-25, D3, Lindstedtsvägen 5, Stockholm, 10:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2009-09-15 Skapad: 2009-09-12 Senast uppdaterad: 2010-10-19Bibliografiskt granskad

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http://www.electrochem.org/meetings/scheduler/abstracts/217/0256.pdf

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Dahlkild, Anders

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