Exploring factors for electrode prototyping for PEM fuel cells
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Materials chemistry (MPMCN), MSc
Publicerad
2024
Författare
Björklund Larsen, Frederikke
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
As the world push to lower carbon dioxide emissions to limit climate change, the need for new
technologies becomes more and more critical. Some emerging technology is hydrogen fuel cells
and amongst them are proton exchange membrane fuel cells. With all new technologies there
are several factors that need development, and this work takes a closer look at the catalyst layer
of the cathode. Setting out to increase the platinum loading in the cathode while at the same
time avoiding cracks, several catalyst inks were made with varying dispersion matrices. The
matrices explored were a) water with ethanol and 1-propanol (2:2:1 weight ratio), b) water
with 1-propanol (2:3 weight ratio), c) water with 2-propanol (2:3 weight ratio), d) water with
tert-butanol (2:3 weight ratio), e) water with 1-propanol and tert-butanol (2:1:2 weight ratio),
and f) water with 1-propanol and tert-butanol (1:1:3 weight ratio).
To get a deeper understanding of the ink’s properties, rheological tests of the inks and visual
analysis of produced electrodes were performed. These analyses found improved coating
quality and a higher viscosity for dispersions with a lower dielectric constant and for inks
containing solvent with a lower vapour pressure. The improved behaviour was attributed to
improved interactions between the ink’s compounds and slower drying of the coatings, leading
to less stresses in the electrodes. An improved electrode quality was also observed when the
inks were left to mature on a magnetic stirrer for several days. The maturation step resulted in
lower viscosity of the inks indicating smaller effective volume fraction of particles and less
electrostatic repulsion and steric hinderance between compounds. A final factor in the process
that was tested was increasing the relative humidity during the drying process. Here an
improved cracking behaviour was observed for the ink containing more water while the
opposite was seen in the ink containing more tert-butanol. These findings point towards the
need for specific drying processes for each individual ink