DEVELOPMENT OF GASKET-LESS CARBON COMPOSITE BIPOLAR PLATES FOR PEM FUEL CELL

Abstract

The bipolar plate is one of the most important components for proton exchange membrane (PEM) fuel cell systems, which provides many functions, such as establishing electrical connections between cells in series, providing separation between gases in adjacent cells, supplying structural support for the stack and creating flow channels for water and gases. Although carbon fiber composite bipolar plates have high strength and stiffness with corrosion resistance in acid environment, it requires much time to assemble a stack as well as high gas tightness of the fuel cell stack to acquire proper performance, which compromises commercialization of PEM fuel cell. Conventional bipolar plates use extra rubber gaskets to seal the stack which requires additional curing process in high temperature that might damage the bipolar plate. In order to reduce assembling time of PEM fuel cell stacks and increase the gas tightness without using extra gasket and curing cycle, innovative gasket-less carbon composite bipolar plates were developed. To ease the assembling of the stacks, special grooves were designed on the edge of the composite bipolar plate for mechanical joining with numerical analysis. FE analysis was performed to investigate the behavior of the gasket-less carbon composite bipolar plates under stack compaction pressure. Mechanical propertied of the grooves were measured by compressive strength test and compared with the FE analysis results. Lastly, sealability test was performed with developed carbon composite gasket-less bipolar plates with grooves to investigate the gas tightness of the stack and to verify the reliability of the design.