A new coating process ensures that fuel gases can be converted into electricity quickly. This lowers the cost of fuel cells that power, for example electric cars. An advantage of these cars is that they take exhaust produce steam.
electric cars produce instead of exhaust gases, water vapor, that’s why they are especially in emerging economies such as China popular (Photo: AP)
Researchers at the Paul Scherrer Institute have developed a coating that makes the fuel more effectively. The novelty of the coating is that it is hygroscopic in some places. The water then flows exclusively via these sites. Thus, the flow of the gases is no longer as in the past disturbed the water.
The new method improves the performance and stability of the fuel cell. The current which is produced in these cells, For example, driving electric cars. The advantage of cars that are powered by fuel cells is that they only produce steam instead of gas. Steam is namely the only chemical product that is produced during the ongoing reaction. Since 2013 production-ready fuel cell cars are available. Researchers worldwide are busy, to increase the efficiency of the cells, thereby reducing the cost of these. The new procedure is according to the researchers suitable for mass production.
Fuel cells generate from the gases hydrogen and oxygen electricity. They produce water that flows out of the cell. A problem has hitherto been to discharge the water from the parts of the cell in which it is undesirable. These are the pores of the gas diffusion layer, which provides for the supply and distribution of the gases to the electrodes of the cell. If water collects there, it impedes the flow of gases and it gets electricity production to a standstill.
Until now, the gas diffusion layer so evenly coated with a water-repellent plastic. The problem of uniform coating however, was that the water has randomly distributed. The pores, which remained free for the passage of gases, thus formed no direct, but an indirect way. Therefore, the gases came only slowly to the electrodes, which minimizes the power of the cell.
The new coating ensures that the water fixed direct way to drain selected. This also arises a direct access for the gases to the electrodes. The Researchers achieved by making the water-repellent coating on the basis of straight paths hygroscopic. This creates water channels through which the water flows. All other areas of the layer remain dry and allow the unhindered influx of gases.
To prepare the water channels, the researchers hydrophilic molecules had to use in the structure of the original plastic. With an electron beam the coating was prepared so that it can bind hydrophilic molecules. The electron beam is guided through a metal mesh, so that two different areas are formed. Where the beam passes through the grid, the original coating can be changed so that it is hygroscopic. Where the beam does not pass through the mesh, the coating remains with its water repellency.
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