Extending fuel cell range
The PEM fuel cell is conceptually a relatively simple electrochemical energy conversion device. In practice, however, getting the fuel cell to operate reliably under the required operating conditions for extended periods of time is not so straightforward. For example, high temperature (above 100 °C) and humidity affect membrane performance, which requires the right amount of water to function. The IMMEDIATE project was set up to develop improved membrane electrode assemblies (MEAs) for PEM fuel cells operating from below freezing to 120 °C at a relative humidity of 25 %. Consortium members built on the work of the earlier, highly successful IPHE-GENIE project by developing catalysts for PEM fuel cells that further reduce the use of platinum (Pt) in MEAs and also increasing catalyst performance and electrochemical stability. This was achieved by designing novel materials for gas diffusion layers and optimising the composition and morphology of both the microporous layer and the electrodes. Researchers also developed new ionomers with high proton conductivity and high thermal and dimensional stability. The evaluation process focused on two areas: determining the performance and durability of the MEAs during use by city buses, and estimating the cost of an alternative powertrain based on the cost of the MEA. New carbon support materials with intermediate surface area and optimised pore structure were also designed and thoroughly characterised. In addition, two catalyst preparation procedures were developed and optimised for the preparation of high-loading Pt catalysts, which were characterised for their Pt loading, Pt size and morphology. IMMEDIATE’s MEA showed excellent durability over 500 hours of demanding bus driving tests. The cost of the MEA decreased significantly, and considerable reductions are anticipated in the estimated total costs of the powertrain, since the system parts contribute very heavily to the total costs. Furthermore, improved operating temperature and humidity should significantly increase marketability of PEM fuel cell technology.
Keywords
Fuel cell, proton exchange membrane, IMMEDIATE, membrane electrode assemblies, platinum
