Heat Treatment for Fuel Cell Catalyst

This technology aims to solve the water production and management problem in the cathode catalyst layer of a PEM Fuel Cell during a high current density operation.

OVERVIEW:
The invention consists of a novel heat treatment process for controlling the ionic polymer/gas interface properties of the fuel cell catalyst layer, which can be incorporated into the fabrication process of the membrane electrode assembly (MEA).

APPLICATIONS:
The potential application is in cathode catalyst layer of a PEM Fuel Cell during a high current density operation where  water production can negatively impact performance by lowering the mass transport of oxygen into the cathode.

HOW IT WORKS:
First, XPS was used to characterize the catalyst layer ionomer-gas interface on top and without the catalyst layer, after the upper layer of the catalyst layer was brushed off, to verify specific heat treatment conditions lead to a hydrophobic or hydrophilic ionomer interface.  Next, the MEA fabrication procedure was modified to ensure the catalyst layer was subjected to suitable heat treatment exposure conditions in order to create an optimal hydrophobic ionomer-gas interface inside the cathode catalyst layer.  Finally, extensive fuel cell tests were completed on the new MEAs under different operating temperatures, flow field types, and air humidification conditions.

BENEFITS:
This approach is simple and inexpensive compared to other research, which involves complicated designs and expensive materials/processes.  

WHY IS IT BETTER:
The use of forced convection method has led to increase of 47% in peak power density at 70°C with interdigitated flow fields and dry air. At a lower temperature of 25°C and with humidified air, peak power increased by more than 133% over the conventional MEA process.  The other natural convection method provides various outcomes but is easy to incorporate with current manufacturing processes.

OTHER APPLICATIONS:
This technology could have possible applications in any product using catalyst; not limited to fuel cells.