| 摘要 |
<p>Fuel cells of the proton exchange membrane type use a sulfuric acid solution as their electrolyte. Electrically conductive bipolar plates separate adjacent fuel cells in a stack of fuel cells that are connected in series to provide higher voltage. Bipolar plates made from most metals (except for the very expensive noble metals such as platinum or gold) become etched by the sulfuric acid solution and/or develop an insulating oxide layer that reduces the electrical output of the cells. A double layer coating has been found that protects bipolar plates from the acid electrolyte. The plates are protected by a layer of corrosion-resistant metal, such as tantalum or a nickel alloy, followed by a layer of tin oxide. Fluorine and/or antinomy doping of tin oxide provides the low electrical resistance necessary for efficient operation of the fuel cells. Chemical vapor deposition is the preferred method for depositing these two protective layers on the complicated contours of bipolar plates.</p> |
