DURABILITY TESTS OF PROTON-EXCHANGE MEMBRANE FUEL CELLS (PEMFC) FOR AUTOMOTIVE APPLICATIONS

The employment of fossil fuels is spread in a wide range of different sectors, such as the residential and the industrial ones, including the transportation as well, not only to generate power but also to generate heat or cold. This high dependency covers many aspects of the modern world in such a deep way that the exploitation of fossil sources has become huge. Nevertheless, it is well known that the combustion of fossil fuels gives as byproduct the emission of CO2 which in turn is reckoned to be the main cause of global warming. The climate has been submitted to more changes in the last few decades than during the whole life of the planet, with huge consequences for the environment. Given this framework, it is normal that the research has finally moved towards new and clean power generation devices. Among them, fuel cells are thought to potentially become a good alternative to traditional power generators, being able to exploit the oxidation of the fuel to produce directly electricity while being noiseless and clean. Among the different typologies of fuel cells, this work aims to analyze the so called Proton Exchange Membrane Fuel Cells (PEMFCs), whose name is given by the material which composes their electrolyte. The material is indeed formed by a polymeric membrane which is able to assure good mobility to the positive ions, while being impermeable to other species. In fact these cells, work through the oxidation of hydrogen and thus the separation of the electrons, whose flow gives electricity, and the protons that go through the membrane to react with oxygen and produce water as byproduct. In this way, the enthalpy of the oxidation of hydrogen to produce water is used to produce electricity, whilst no combustion occurs. One of the main features of these devices is that they need to work at low temperature, and thus they allow fast start-ups and shut-downs, which makes them ideal for automotive applications. The main goal of this work is indeed to analyze how the durability of the fuel cells is affected by the submission of a load that recalls the traffic conditions. This aspect is investigated through the performance of durability tests and the exploitation of the most typical fuel cells diagnostic tools: polarization curves and the electrochemical impedance spectroscopy.