Dear Praveena,

there is lots of literature about how to measure a polarization curve of a "fuel cell" depending on so many parameters for operating conditions etc. that a single and simple advice here is definetely not possible.

Let us start from the scratch:

What kind of fuel cell do you want to investigate? Low or high temperature PEM, alkaline, DMFC, MCFC, SOFC ... and so on.This determines the technical setup for operating the fuel cell.

Do you have a test bench available? Do you know how to operate the testbench to setup the operating conditions required? If not make yourself familiar first with the test bench, including required calibration of mass flow controllers, temperature sensors etc. How do you determine that the system values given for a parameter, example flow rate, are valid and "real"?

What is the question behind the measurement of the polarization curve? That often determines operational parameters like gas compostion and flow rate, stoichiometry, temperature, pressure, load currents etc. Make sure your test station is capable of setting all operating parameters required. Example here: flow rates of gases with mass flow controllers at very low load currents under constant stoich conditions.

A fuel cell usually requires a break-in and defined start-up procedure before load can be applied and current be drawn. It also depends on the kind of fuel cell you want to investigate. Examples here: SOFC and/or high temperature PEM FC.

If you want to determine the anode and cathode contributions within a polarization curve separately you need a reference electrode, either on anode or cathode side. Check your setup with a reference electrode before starting the real experiments.

And do not forget: A polarization curve is only one method to investigate fuel cells. Other electrochemical methods like linear sweep and cyclic voltametry as well as electrochemical impedance spectroscopy are also important methods to answer specific "questions" about the FC and its behaviour under load. That brings back the question: What do want to know and learn from a polarization curve?

Kind regards

Peter

To measure the polarization curve in a given fuel cell, you need to measure two things:

1) Measure the cell's discharge current in mA.

2) Measure the corresponding cell voltage in volts.

Plot your data as follows: On the Y-axis, plot the voltage (V) and on the x-axis plot the discharge current (mA).

When the fuel cell is not discharging, that is the discharge current = 0, the fuel cell voltage is at its maximum value. As current is discharged, the cell voltage drops.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA  

Dear Praveena,

Peter has most thoroughly covered all the questions you need to ask, but I wanted to add some specific recommendations if you're looking to buy a new setup.

Assuming you meant PEMFCs or AEMFCs, for test benches themselves, Scribner is a good bet - half the price of most competitors, more functions, and . You need to figure out the size of cells you want to test (5 cm^2, 25, 50, stack...) and whether you're going to be looking at accelerated stress tests - your requirements differ the most depending on these.

As Peter mentioned, you need to pair it with a good potentiostat for CV/CA and FRA for EIS (either 2 machines or combined). Solartrons are great if you have the budget (still expensive used); I'm entirely disaffected by my PARstats and still love my ancient Solartrons. There are quite a number of companies that make these; if you're going for someone else, it's worthwhile to demo the software and ensure that the EIS actually gives good data to the highest range you need (e.g. my PARstats are rated to 2 MHz, but typically goes unstable around 100kHz).

Best regards,

Ben

I totally agree with what Peter said, he has stated all the inquiries you need to ask, but I would like to mention important note you must take in your writing. It is better to plot your data as follows: On the Y-axis, plot the voltage (V) and on the x-axis plot the discharge current (mA).