Reduction of start-up/shut-down damage of fuel cells

摘要

Procedure for the operation of an electrochemical conversion device comprising a membrane electrode array, an anode flow field and a cathode flow field, where:the membrane electrode array includes a proton exchange membrane that separates an anode and a cathode of the array;the membrane electrode nano-array includes a catalyst supported by a medium with a relatively high surface;the proton exchange membrane includes a material characterised by improved proton conductivity under wet conditions; andwhere the procedure includes that:a start sequence is initiated where a hydrogen-containing front is driven through the anode stream field, exposing the carrier material and the electrode catalyst analyser to corrosion and catalyst resolution due to relatively high voltages developed at the membrane electrode array cathode;the electrochemical conversion device is operated under wet conditions by driving a hydrogen gas through the anode flow field and an oxygen-containing gas through the cathode flow field; anda shut-off sequence is initiated where a substantially dry gas is driven through the cathode-flow field for a period sufficient to reduce the water content of the proton exchange membrane to less than 50% RF, with the equivalent RF of the relative humidity of a gas in equilibrium with the proton exchange membrane.