A large motor vehicle manufacturer, while researching the anode and cathode material for a mobile fuel cell stack, determined that as the thickness of the material decreases the efficiency of the fuel cell increases. However, the research also showed that the efficiency will decrease as the membrane gets too thin. This is most likely a result of the permeation rate of hydrogen and oxygen through the membrane. This interaction between the gasses and the membrane has led the manufacturer to research a target permeation rate for the fuel (hydrogen) and the oxidant (oxygen) through the membrane material. A request was sent to MOCON to determine these permeation rates.
Due to the operating conditions of a fuel cell and the characteristics of the material, MOCON needed to develop a method to analyze the hydrogen permeation rates at elevated temperatures and pressures. Typically, permeation rates will rise with both increases of pressure and temperature, however the rates were unknown. This permeation rate is required for the development of the specifications in the anode and cathode structure, for both material type and thickness. The oxygen permeation rates were analyzed using current MOCON patented technology employed today, with modifications to the methodology.
Many of the materials used in the fuel cell stack are brittle, especially when unsupported. The method developed supported the material and continued to allow the diffusion of the permeated gasses to the sensor. The apparatus allowed the materials to withstand changes in pressure and both static and cyclical temperature variations.