A Review of Coated Metallic Bipolar Plates for Proton Exchange Membrane Fuel Cell (PEMFC) 2023-01-0488

The sunrise vision for hydrogen economy lies in efficient, lightweight and durable devices which can convert hydrogen energy into electrical energy. Proton Exchange Membrane fuel cell (PEMFC) is a key hydrogen energy conversion system for transport sector. The efficiency and durability of PEM fuel cell largely depends on cathode electrode and membrane and Bipolar plates (BP Plates) plays an important role in it. BP plates perform the important functions of transporting fuel gases to reactive sites, collecting charges and thus conducting electricity from cell to cell, moisture adjustment of membrane, transport of produced water and provides essential mechanical strength to fuel cell stack. It makes BP plates the backbone of PEM Fuel cell power stack. For BP plates to perform intended functions, it is highly desirable BP plates to possess excellent properties on corrosion resistance, electrical conductivity, thermal conductivity, water wettability, weldability and formability. There is a conventional wisdom to use graphite plates as BP plates for the obvious advantages of high electrical conductivity and corrosion resistance. However, the unavoidable disadvantages, durability against shock and vibrations, cost and weight, machinability and limited design flexibility associated with Graphite BP plates shifted the focus to metallic BP plates. In recent times, numerous metallic BP plates are being developed. However bare metallic BP plates lack the basic performance requirements of corrosion resistance and surface/contact electrical conductivity. In order to improve these properties, specifically corrosion resistance in fuel cell environment, multiple coating systems and coatings processes are being developed. The development in BP plates coatings is primarily focused on reducing or eliminating Interfacial Contact Resistance (ICR) and improving corrosion and oxidation resistance. This paper reviews numerous coating systems, which are being developed for metallic BP plates including the process for coating deposition and key characterization techniques to evaluate the performance of metallic bipolar plate.