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Elektrochemische Impedanzspektroskopie zur experimentellen Untersuchung des Betriebsverhaltens eines PEM-Brennstoffzellenstacks

Petters, Valentin (2017) Elektrochemische Impedanzspektroskopie zur experimentellen Untersuchung des Betriebsverhaltens eines PEM-Brennstoffzellenstacks. Master's, Universität Stuttgart.

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This Master Thesis characterises the operational behaviour of low temperature fuel cell stacks with electrochmical impedance spectroscopy and the currunt interrupt method. The PEM-FC-Stack HD10, a fuel cell system by Hydrogenics, will be used for the investigations. The aim is to gather information about every cell in the stack by only measuring at one point over the whole stack. At first the test setup will be described and the modifications of the fuel cell stack needed for the measurements. Subsequently EIS measurements at stationary states of operation are conducted to quantify the moisture of the stack dependent on operating conditions and temperature. To accomplish that the fuel cell operation temperature is varied at different loads. The results of 16 generic single cell measurements are compared with measurements over the whole stack of cells. With the comparison of the single cell measurements with those of the whole stack it can be found that to quantify the state of the cells by a single measurement over the whole stack is not expressive enough. To use the full potential of the impedance spectroscopy measurements with different excitation frequencies have to be performed. Especially at low frequencies of oscillation the measurements take a lot of time. To shorten the length of the experiments, tests without the low frequencies are conducted. It can be shown that the time of the measurements can be lowered by 80%, but only the information about the electrolyte resistance can be gained from that. The current interrupt method is an other way to quantify the operational behaviour of a stack comparable to the EIS measurements. For that voltage measurements of the whole stack are made with a sample rate of 50 kHz while a sharp drop of the current is performed. The results show that the effort of the CI method is not less than that of the EIS measurments. In the evaluation of the CI-tests it is not possible to quantify the electrolyte resistance, the moisture or the operating condition of the stack.

Item URL in elib:https://elib.dlr.de/114565/
Document Type:Thesis (Master's)
Title:Elektrochemische Impedanzspektroskopie zur experimentellen Untersuchung des Betriebsverhaltens eines PEM-Brennstoffzellenstacks
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Date:31 August 2017
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Number of Pages:126
Keywords:PEM-Fuelcell, EIS, System
Institution:Universität Stuttgart
Department:Institut für Raumfahrtsysteme
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Weiss-Ungethüm, Jörg
Deposited On:30 Nov 2017 16:51
Last Modified:07 Feb 2020 13:52

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