In-situ diagnostic tools for hydrogen transfer leak characterization in PEM fuel cell stacks part III: Manufacturing applications

This work describes a novel diagnostic technique for detection and isolation of manufacturing defects in polymer electrolyte fuel cell stacks. Two of the main causes of early stack failure are membrane pinholes and electric shorts. Membrane pinholes result in the local hydrogen crossover from anode to cathode, which reduces fuel utilization. With the growth of the pinhole, the crossed over hydrogen exits the cathode as hydrogen emission. When this emission passes the safe lower explosion limit of 4% hydrogen in air, the stack reaches its end of life (EOL). Alternatively, a low resistive point between the anode and cathode results in current flow through the contact point and local heat generation. This could burn the membrane and result in EOL of the fuel cell stack. A diagnostic technique is proposed to detect cells in which membrane pinholes or electric short occur. The technique allows both failure mechanisms to be isolated by means of a straightforward algorithm. The detection of the failure can be used as a pass/fail criterion during fuel cell stack manufacturing, whereas the isolation of the failure modes can be used to inform suitable repair procedures to be performed on the failed stacks