Completed notes of the course

Pagina 1

PEMFC TECHNOLOGY We have the H2 compartment and air compartment, in the middle we have the electrolyte which permits ion transport. The electrolyte is impermeable to the gas and separate anode and cathode. Then there is an external connection between the 2 electrodes à the electrode is a conductive component used to collect electrons H2 get in touch with the electrode that has a catalyst on the surface and permit this reaction: 𝐻!→2𝐻"+2𝑒# H+ will move through the electrolyte, the electrons will move externally creating a direct current and they will meet at the surface of the other electrodes where O2 is present so that: 2𝐻"+12𝑂!+2𝑒#→𝐻!𝑂 In the end we are feeding H2 and O2 in order to have water Þ we are having 2 electrochemical reactions. It’s an open system. Power and stored energy are totally independent: power depends on the type of fuel cell, especially the area; while the stored energy depends on the tank that is connected to the fuel cell. You can follow the blue path and have the inverse reaction which is the one of the electrolyzer. In the commercial field fuel cells and electrolyzers are diIerent devices because the catalysts used are diIerent. Batteries are completely closed systems à power and energy stored are connected. They are designed to be charged and discharged, that’s why the reaction goes forward and backward. Now we have Lithium batteries, this element is hosted in graphite layers, while O2 is contained in a metal-oxide (CoO2). From an energy point of view, Li in that state, is very similar to Li in a metallic form. The electrolyte is liquid to permit Li ion transport Li is able to react because it will be more stable, but we don’t do a full oxidation because we want to go back having viceversa reaction Þ in the end we transfer Li from anode to…