In Situ Mapping of Electrode Potential in a PEMFC

Abstract

An overview is given of the use of reference electrodes in polymer electrolyte membrane fuel cells (PEMFCs). The two most common types of reference electrode employed in PEMFCs are the reversible hydrogen electrode and the dynamic hydrogen electrode, which have the advantage of minimizing chemical contamination of the fuel cell. Conventional configurations include internal reference electrodes, which are constructed by sandwiching the electrode between two membranes, and external reference electrodes, which are typically connected to the edge of the membrane via a salt bridge. A recent breakthrough is the development of an innovative reference electrode array with a through-plate configuration, which makes possible for the first time accurate mapping of the variation in electrode potential across the active area of an operating PEMFC. This configuration overcomes the major limitations of conventional fuel cell reference electrodes in that ohmic drop, potential distribution and electrode edge effects in the membrane are negated.