Adaptive Process Control and In-Situ Diagnostics for High Temperature PEM MEA Manufacturing

The most critical step in high temperature proton exchange membrane (PEM) MEA manufacturing is sealing of the membrane between the two electrodes. This sealing process is typically conducted using a precision hydraulic thermal press. In order to achieve cost-effective high-volume MEA manufacturing, it is important to reduce the variability in MEA performance due to variations in incoming material properties and dimensions, and to reduce the unit process cycle time. This paper explains the application of real time adaptive process controls (APC) combined with effective in-situ diagnostics during the MEA sealing process to achieve greater uniformity and performance of high temperature PEM MEAs. The in-situ impedance measurement is carried out in a precision thermal press using a milliohmmeter by reading the complex impedance of the MEA at 1 kHz as the components of the MEA are sealed. This signal is then used to adjust the pressing process parameters in real time to achieve more uniform MEA performance. An experiment was carried out in an attempt to identify the impedance parameter which correlated most closely with the MEA’s future performance. Using these impedance parameters during pressing, we are able to reliably produce MEAs using the real time APC technique that perform consistently in a single cell test fixture with more than a 50% reduction in pressing time.