Ballard Power Systems Corporation

John Ka Chan

Clarence Y Chow

David P Wilkinson

Jean St-Pierre

Joy A Roberts

Adrian James Corless

Boguslaw M Wozniczka

Cindy J Longley

Erik Paul Johannes

By Patricia Allan, Administrator

Derek E Allan, Deceased

A method and apparatus is provided for operating an electrochemical fuel cell with periodic momentary fuel starvation at the anode. It is believed that such momentary periodic fuel starvation conditions cause the anode potential to increase, resulting in the oxidation and removal of electrocatalyst poisons from the anode electrocatalyst and improved fuel cell performance. In a preferred method, while successive localized portions of the fuel cell anode are momentarily periodically fuel starved, the remainder of the fuel cell anode remains electrochemically active and saturated with fuel such that the fuel cell is continually available to generate power.

Method and apparatus for operating an electrochemical fuel cell with

A method and apparatus are provided for distributing water produced by the electrochemical reaction to an ion-exchange membrane in a electrochemical fuel cell. Water distribution within a fuel cell is improved to reduce membrane dryness near the oxidant stream inlet and to also reduce saturation of the oxidant stream near the oxidant stream outlet, thereby reducing electrode flooding. The method comprises periodically reversing the flow direction of an oxidant stream through a fuel cell flow field. The apparatus comprises an oxidant stream flow switching device for periodically switching the flow direction of an oxidant stream through a fuel cell flow field. In one embodiment the apparatus further comprises a water recycler for capturing water from the oxidant exhaust stream and returning the captured water to the oxidant supply stream when the flow direction is reversed.

Method and apparatus for distributing water to an ion-exchange membrane

An electrochemical fuel cell assembly comprises a pair of separator layers and a membrane electrode assembly interposed between the separator layers. The membrane electrode assembly comprises a pair of electrodes and an ion exchange membrane interposed therebetween, the electrodes having electrocatalyst associated therewith defining an electrochemically active area. Each of the separator layers comprises one or more reactant stream passages in fluid communication with one of the electrodes. At least one of the separator layers further comprises one or more coolant stream passages which do not superpose the electrochemically active area of the adjacent membrane electrode assembly, and are fluidly isolated from the reactant stream passages.

Integrated reactant and coolant fluid flow field layer for an

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Vancouver, Canada

John Ka Chan