Low-cost fuel cell vehicles come a step closer

In the push to develop alternative energy forms, PEMFCs based on hydrogen fuel have gained widespread interest for transport applications. A key component of PEMFCs contributing significantly to their cost and weight as well as to the stack volume is the bipolar plate (BPP). Although metal-based ones are particularly attractive, a protective coating is required to avoid corrosion and keep the interfacial contact resistance low.

BPPs serve to separate the fuel from oxidant gases, distribute reactant gases to the cells and deliver electron flow through the PEMFC stack. In the EU-funded project 'Stable and low cost manufactured bipolar plates for PEM fuel cells' (STAMPEM), scientists are improving the existing or developing new coating materials for BPPs that are made of low-cost metals.

Scientists are working on different materials and concepts to come up with a low-cost, high-performance BPP that fulfils both technical and economic requirements. Metal nitrides, conductive polymers and carbon composites are being developed and tested.

STAMPEM is investigating and developing new techniques to achieve good adhesion and low contact resistance between the BPP metal substrate and the coating. Project members are initially testing coatings ex situ in a three-electrode electrochemical set-up. Given that the material is promising, they are further investigating its suitability in a real fuel cell with in situ techniques. Structured metallic plates are coated and put in a small-scale test cell where accelerated stress tests degrade the plate materials.

So far, accelerated stress tests of BPPs in fuel cells have revealed coatings with comparable properties to gold-coated stainless steel that serves as a reference point. Work on BPP manufacturing and processing is progressing, with substrate pre-treatment, coating techniques and the stamping process being the most important aspects.

STAMPEM is facilitating implementation of the European Strategic Energy Technology Plan (SET-Plan), helping to develop suitable technologies to commercialise hydrogen and fuel cell vehicles. Besides applications within the automotive industry, project findings may also have positive implications for stationary power generation.