Plasma-Coating of Ti and Ta on Graphite Composite As Corrosion-Improved Bipolar Plate in PEM Electrolysis
We developed a plasma process to deposit protective coatings on graphite composite bipolar plates. Therefore we used unbalanced magnetron sputtering of Ti and Ta. A new magnetron sputtering process was applied to keep the temperature of the graphite composites constant. Furthermore a combined plasma-process was used to enhance the stability of the deposited layer by activating the graphite composite. The Ti and Ta coatings were tested in a heated (T = 353 K) electrochemical cell amperometric at 2 V vs. RHE and by cyclic voltammetry in oxygen saturated 0.5 M H2SO4. We figured out the layer quality with the 4-Point Probe before and after each experiment. Furthermore we evaluated the film characteristics by microscope (SEM, light microscope), XRD and XPS.
We could demonstrate that the coating is protecting the graphite composite as bipolar plate material in harsh electrochemical environment which was choosen close to real conditions in PEM Electrolyzers. Thereby it should be possible to lower the cost of bipolar plates in PEM electrolyzers substantial.
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