PNNL

Abstract

The bipolar plate is the most bulky component in the PEMFC stack (in both weight and volume) and one of the most expensive to manufacture. It serves not only as the electrical junction between serially connected cells, but also performs several other key functions in the device: • Distribute the fuel and oxidant uniformly over the active areas of the cells. • Facilitate water management of the membrane to keep it humidified, yet mitigate flooding. • Act as an impermeable barrier between the fuel and oxidant streams (particularly H2) to maintain the hydrogen gradient across the membrane necessary for high power output. • Provide some measure of structural support for the stack. • Remove heat from the active areas of the cells. The use of metal-based bipolar plates in PEMFC stacks potentially offers a number advantages particularly for transportation applications including: low-cost, mass-production via stamping or embossing of sheet product; fabrication in very thin form (