In principle, all vehicles with alternative drives have the potential to take people from A to B in the future in a climate-friendly manner. If they are powered by batteries, however, there are still many challenges that need to be solved. During the production of the batteries alone, a lot of CO2 is created in today’s electricity mix because electrical energy is required to manufacture them. Furthermore, the range of battery electric cars is not really suitable for everyday use at present; there are too few charging points and the charging process itself takes too long. Fuel cells offer an alternative to batteries, particularly for heavier electric vehicles that travel long distances. This is because they produce the electricity that the electric motor needs directly onboard.
To achieve this, the car is first fueled with hydrogen, which can be obtained from CO2-neutral electricity. In the vehicle, the fuel cell converts the hydrogen back into electricity. The principle works like this: the positively charged hydrogen protons migrate from the anode through a polymer electrolyte membrane (PEM) to the cathode, where they react with atmospheric oxygen to form water. In the process, an excess of negatively charged hydrogen electrons is produced at the anode. If these are connected to the cathode via a separate circuit, that is where they will go: electric current flows. Water vapor and heat are generated as ‘waste products.’ Because this involves an oxidation process without a flame, it is also referred to as cold combustion.
In the case of cold combustion, the aim is to convert as much energy as possible from hydrogen into electricity – and not into heat, which would remain largely unused in the vehicle. This is precisely where the black nonwoven comes into play. “The gas diffusion layer is located directly on the catalytically coated membrane and has the task of optimally distributing the hydrogen and airborne oxygen into the reaction process,” Banhardt explained. The more homogeneously the gases are distributed and the more uniformly air can flow over the entire cross section, the more electricity is produced via cold combustion. In addition, the gas diffusion layer has the task of removing the waste heat and water vapor. That is why it is coated in a similar manner to a Teflon pan. The steam bubbles along it in a channel system, through which it is discharged.