The fuel cell
The crucial differences are beneath the hood of the A7 Sportback: The fuel cell in the Audi technology demonstrator is installed at the front, mirroring the conventional A7 Sportback with combustion engine. Because the exhaust system only has to handle water vapor, it is made of weight saving plastic.The fuel cell itself comprises over 300 individual cells that together form a stack. The core of each of these individual cells is a polymer membrane. There is a platinum-based catalyst on both sides of the membrane.
This is how the fuel cell works: Hydrogen is supplied to the anode, where it is broken down into protons and electrons. The protons migrate through the membrane to the cathode, where they react with the oxygen present in air to form water vapor. Meanwhile, outside the stack the electrons supply the electrical power – depending on load point, the individual cell voltage is 0.6 to 0.8 volts.