Characteristics of the PEMFC repetitively brought to temperatures below 0°C

Freezing of water in a polymer electrolyte membrane fuel cell (PEMFC) may cause severe problems in driving a fuel cell vehicle during the winter time. Characteristics of PEMFC which suffered low temperatures below zero celsius were examined with thermal cycles during which the temperature of the environment chamber was cycled from 80 to -10 degreesC. With the thermal cycles, the cell performance was degraded due to the phase transformation and volume changes of water. Effects of freezing of water in a PEMFC on the electrode structure and polarization resistance were examined by Brunauer, Emmett, Teller analysis, cyclic voltammetry, and ac impedance spectroscopy. (C) 2003 The Electrochemical Society.