Soldering a gas diffusion layer to a stainless steel bipolar plate using metallic tin

摘要

A novel investigation to decrease the interfacial contact resistance of stainless steel bipolar plates was performed. A thin layer of Sn was electrodeposited onto a bipolar plate and subsequently joined with a gas diffusion layer through hot-pressing at a temperature around the melting point of tin. This procedure was optimised, depositing 30 mu m of Sn onto the stainless steel bipolar plate before hot-pressing at 230 degrees C and 0.5 bar for 20 min. A contact resistance of 5.45 m Omega cm(2) at 140 N cm(-2) was obtained, with low values maintained after exposure to both in-situ and ex-situ conditions. The in-situ testing in a fuel cell produced excellent results, with minor increases in contact resistance from 8.8 to 9.2 m Mu cm(2) and decreases in cell voltage from 0.714 to 0.667 V after 200 h of operation. These values are comparable to gold plated stainless steel, showing that combining a gas diffusion layer with electrodeposited Sn through hot-pressing is a promising low-cost coating for bipolar plates in PEM fuel cells. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.