Formation of 3D graphene–Ni foam heterostructures with enhanced performance and durability for bipolar plates in a polymer electrolyte membrane fuel cell

Abstract

Improving the lifetime and the operational stability of polymer electrolyte membrane fuel cells (PEMFCs) is critical for realizing their implementation as a practical and highly-efficient energy conversion system. However, the corrosion of metal bipolar plates, which are a key component in PEMFCs, leads to decreased efficiency and durability. Here, we prepared poly(methyl methacrylate)-derived multilayer graphene (Gr) coatings with high crystallinity and a continuous three-dimensional (3D) structure using a rapid thermal annealing (RTA) system for short periods (≤5 min). The resulting 3D Gr-coated Ni foam is demonstrated to act as a bipolar plate with long-term operating stability. Electrochemical analysis revealed that the synthesized graphene on Ni foam outperforms bare Ni foam and amorphous-carbon-coated Ni foam by providing a two-order-of-magnitude lower corrosion rate in the operating environment for a PEMFC. In addition, after stability tests in a destructive environment, the 3D Gr-coated Ni foam maintained its outstanding interfacial contact resistance of 9.3 mΩ cm² at 10.1 kgf cm⁻². A H₂/air PEMFC fabricated using the Gr-coated Ni foam embedded within the groove of a graphite-based bipolar plate exhibited a substantially enhanced power density of ∼967 mW cm⁻² at a cell potential of 0.5 V with further advantages of weight reduction and no additional machinery process for the gas flow channel. This facile coating approach addresses one of the key limitations of current metal bipolar plates in PEMFCs, and paves the way to further enhance energy conversion systems through interface engineering.