An overview of electro-osmosis in fuel cell polymer electrolytes

Electro-osmosis, the transport of water with protons, in polymer electrolyte fuel cell membranes is important because it effects water management within an operating cell on both a global and local level. The electro-osmotic drag coefficient is the number of water molecules transported per proton and is a quantitative measure of the extent to which electro-osmosis occurs in a given polymer electrolyte. The methods for which electro-osmotic drag coefficients have been determined are reported. An effort is made to report proton electro-osmotic drag coefficients extensively, while a few non-proton cation electro-osmotic drag coefficients have been chosen for illustrative purposes. The results reported have implications for fuel cell performance and in the development and characterization of new polymer electrolyte membranes.