Research and Development Capability
Johnson Matthey has had significant activities in fuel cell and electrochemical R&D since the 1950’s – initially in alkaline fuel cells (AFC) for the NASA space program, then phosphoric acid fuel cells (PAFC) for large stationary power generation/combined heat and power (CHP). Since the late 80’s R&D has focussed on polymer electrolyte fuel cells (PEMFC) for hydrogen, reformate and direct methanol applications.
The key component in a PEMFC system is the membrane electrode assembly (MEA). The design and performance of the MEA has a major impact on system size, efficiency and cost. Johnson Matthey’s leading position in manufacturing of component materials and complete MEAs for PEM fuel cells is based on long-term progress in the R&D activities that support our manufacturing capability. It remains a critical requirement to further develop these materials to achieve both the cost and performance targets necessary for the successful commercial exploitation of PEMFC systems by our customers in stationary, mobile and portable/electronics applications.
The requirements of these markets impose individual, but aggressive targets on PEMFC systems: increased energy density, fuel efficiency, product lifetime, reduced cost and system simplicity and compactness. Each of these top-level application targets translates into specific technical improvements required in the catalyst, electrode catalyst layer, membrane, gas diffusion layer and MEA construction, eg: improvement of electro-catalytic activity and selectivity, optimisation of anode and cathode catalyst layer morphology, optimisation of the membrane-catalyst interface and improved water management.
The major component materials within the MEA are the subjects of continuing intensive development at Johnson Matthey. In the area of electro-catalysts, Johnson Matthey has made significant progress using a new range of highly active materials for PEM cathodes and anodes:
- Improved oxygen reduction catalysts to bring about increased cell efficiency and reductions in the loadings of platinum required.
- Improved anode catalysts for improved tolerance to impurities in hydrogen rich fuel streams derived from reforming fuels such as natural gas or gasoline, and for increasing power densities that can be attained from direct methanol fuel cells.
Other principal materials within the MEA are also under continuing intensive development at Johnson Matthey, based on the needs of fuel cell system developers to simplify system design and operation as much as possible, while maintaining good efficiency. This includes the use of thin membranes (20-50 microns). The challenge is to develop mechanically robust and chemically stable membranes in order to achieve the lifetime requirements for the MEA product. The following things are also important to control: water movement across the membrane; maintaining an effective interface between the membrane and catalyst layers; and the interface between the catalyst and gas diffusion layers (GDLs).