TY  - THES
AU  - Karacan, Cinar
TI  - Entwicklung von nickelbasierten katalysatorbeschichteten Diaphragmen für die alkalische Wasserelektrolyse
VL  - 679
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Jülich
M1  - FZJ-2025-04772
SN  - 978-3-95806-860-5
T2  - Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment
SP  - 146
PY  - 2025
N1  - Dissertation, RWTH Aachen University, 2025
AB  - Energy storage plays an important role for the weather dependence of energy production via renewable energy power plants. One way of energy storage is the electrochemical production of hydrogen via water electrolysis. A well-known technology is alkaline water electrolysis. The advantage of alkaline water electrolysis over the acidic PEM electrolysis is the use of nonplatinum metal catalysts. However, the high gas impurity, which is caused by the porous diaphragms and the mixing of the electrolytes, shows a big problem for the dynamic operation of the electrolyzer, which is important for the direct connection to renewable power plants. To counter this problem, spacers are installed between the electrodes to reduce gas impurity. However, this leads to high ohmic losses and thus to a low power density. These power losses are not competitive with the high power densities of acid PEM electrolysis, which use a zerogap constellation. These losses of power densities are compensated by larger cell areas, but results in high system costs, offsetting the advantage of non-platinum group catalysts. Based on this background, this work deals with the development of new electrode systems for classical-alkaline electrolysis. First, a new measurement protocol for alkaline single cell tests is developed to ensure a reliable evaluation of these new electrode systems. Then, nickelbased catalyst powders are tested via the rotating disk electrode for suitability as HER catalysts for the new electrode system. The most suitable HER catalyst is then coated onto the Zirfon® diaphragm in the zero-gap constellation via the doctor blade process and tested with various parameters. The power density, long-term stability and gas purity were investigated with different electrode thicknesses and binder proportions. It was possible to develop a catalyst coated diaphragm with a Raney nickel HER catalyst for classical alkaline electrolysis in this work. In this work, the best formulation was able to reduce the overvoltage by 270 mV at 300 mA cm-2 compared to the benchmark, which consisted of an uncoated diaphragm. This reduction consisted mainly of the higher catalytic activity of the Raney nickel. However, the new electrode system showed lower long-term stability than the benchmark, which resulted from the successive reduction in catalytic activity. The gas purity tests showed that the catalyst-coated diaphragm can find its  application in the zero-gap constellation in atmospheric electrolyzers, where a partially separated electrolyte cycle prevails.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)11
DO  - DOI:10.34734/FZJ-2025-04772
UR  - https://juser.fz-juelich.de/record/1048642
ER  -