Corrosion-protection of moulded graphite conductive plastic bipolar plates in PEM electrolysis by plasma processing

Abstract

Proton exchange membrane electrolysis is one of the key technologies for the implementation of renewable energy. The main advantage is the conversion of electrical energy into storable chemical energy. The objective of this work is to enhance our understanding of protective coatings for carbon-polymer composite compound materials used as bipolar plates in acidic electrolysis cells. A two-step plasma process was developed to deposit a corrosion protection. As a first step, the composite compound surface was roughened by applying RF high voltage and using it as a powered electrode. As a second step, titanium coatings were deposited by pulsed DC magnetron sputtering. The plasma process was monitored by in-situ temperature measurements. The corrosion resistance of the coated compound surface was evaluated by cyclic voltammetry and chronoamperometry at 2 V vs. SHE as well as light microscopy. Furthermore, we analysed the activation effect by SEM; the titanium coatings were analysed by the van-der-Pauw method and SEM.