Carbon-based coatings for metallic bipolar plates used in proton exchange membrane fuel cells

Proton exchange membrane fuel cells (PEMFCs) have been promoted more than 100 years and are in the forefront of the large-scale commercial application with the technology breakthrough of key components and stack. As a key component in PEMFCs, bipolar plates (BPPs) can distribute reaction gases, collect current, remove product water, and cool the stack. Metallic BPPs have superior manufacturability and cost effectiveness, higher levels of power density, and high mechanical strength, and have been regarded as an alternative to graphite BPPs. Surface coatings are essential to metallic BPPs because they enhance corrosion resistance and electrical conductivity. Carbon-based coatings have attracted considerable attention from both academia and industry owing to their merits of high performance and low cost. In this paper, a comprehensive survey is presented on the recent progress in carbon-based coatings in terms of evaluation methods, material design, deposition process, and coating performance. Pure amorphous carbon (a-C), metal-doped a-C film, and metal carbide (Me-C) are summarised. Carbon nanotubes (CNTs), graphene, and C-60 are discussed as well. Finally, technical barriers and developing trends are presented in the application of carbon-based coatings for metallic BPPs in PEMFCs. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.