Now, I am working on Polybenzimidazole (PBI) proton exchange membrane of fuel cell at high temperature (HT-PEMFC). I want to measure the proton conductivity of PBI by EIS. Without fabrication of membrane electrode assembly (MEA), only for using PBI membrane to measure proton conductivity, is it possible?
Actually I want to optimize the acid doping level of PBI membrane as concentration and temperature for higher proton conductivity.
Yes that is possible
usually one is taking 4 platin wires, pressed at a distance of 1cm onto the membrane. The both outer wires are connected to the AC current source, the inner both to the sensing inpu. You may take an AC milliohmmeter or a LCR meter.
Place the membrane in a container with hydrogen gas and a temperature control
That's it
Hans
Thanks Deon Hines.
Actually I want to measure the proton conductivity of PBI membrane at over 100oc with dry atmosphere, not for electrical conductivity. Have any idea? Please suggest me.
A convenient way to get the value you seek is to do conventional broadband dielectric spectroscopy of your membrane between brass (preferably gold coated) electrodes. The electrodes are blocking. You should prepare the membrane at a known humidity, since the results will most likely be humidity dependent. I suggest measuring from 0.1 or 1 Hz to 1 MHz if you can. If you measure at different temperatures, above and below 150C, as a function of frequency, you will be able to differentiate the ionic conductivity from the electronic conductivity. The electronic conductivity will increase with increasing frequency (it will have a positive slope of 1 in a log conductivity vs log frequency) and the ionic conductivity will appear as a separate component deviating from the electronic component at lower frequencies. Examples of such spectra for a type of polyimidazolium membrane we synthesized are shown in Figures 3-7 in the attached proceedings paper. The low frequency asymptotes give good quantitative measures of ionic conductivity.
Coat your membrane sample with silver paste but the both side coating should not touch each other. Then go for broadband dielectric spectroscopy. Draw the Nyquist plot (graph Z real Vs Z imaginary), then fit the graph with semi circle and consider the X intercept or put the minimum value of Z real at high-frequency region as resistance(R).Then put it in formula to find out resistivity and then calculate conductivity.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry