Chapter 11 - Bipolar plates and flow field design

Abstract

Bipolar plates are key components in proton exchange membrane fuel cell stacks, and they fulfill important functions and requirements to allow fuel cell stacks to achieve high power density, high efficiency, low cost, and long lifetime in practical applications. In this chapter, the focus is on the fundamentals of the latest developments and state-of-the-art knowledge and technology for practical applications, without a lengthy review of rich literature on the subject. First, the functions and requirements of bipolar plates are stated, then flow field designs as the major structural features fulfilling one of the key functions for reactant gas distribution to proper membrane electrode assembly surfaces are described, fundamental designs and principal design improvement features are presented, and their incorporation leading to the state-of-the-art designs is illustrated. Proper selection of materials is presented in the category of graphite, carbon composites, and metals, as well as their pros and cons. Manufacturing methods utilizing the unique properties of the selected materials are provided that are practiced in the industry. The chapter ends with a discussion of comparison of the various bipolar plates used in practice. The combinations of proper materials, flow field designs, and methods of manufacturing developed for the bipolar plates allow the achievement of commercial targets.