Potential sweep vs current sweep for a Polarization Curve

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Discussion Overview

The discussion revolves around the methods for obtaining a polarization curve for a fuel cell, specifically comparing the approaches of applying current versus varying voltage. It touches on the implications of using different measurement techniques and the equipment limitations faced by the participants.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires whether it is acceptable to change the voltage and measure the current instead of applying current and measuring voltage, noting equipment limitations.
  • Another participant asserts that applying current and measuring voltage is a different method from varying potential and measuring current, suggesting that the latter is a form of voltammetry.
  • A third participant confirms their approach of varying potential and measuring current, referencing literature that reports voltage as a function of current density.
  • One participant questions the terminology used, asking if it is "current applied" or "current drawn," emphasizing the importance of voltage drop under load in the context of fuel cells.

Areas of Agreement / Disagreement

Participants express differing views on the methods for obtaining polarization curves, with no consensus reached on the appropriateness of the voltage sweep approach versus the current sweep method.

Contextual Notes

There are limitations regarding the definitions of terms used, such as "current applied" versus "current drawn," and the discussion does not resolve the implications of using different measurement techniques on the polarization curve results.

JoJoQuinoa
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Hello,

I'm trying to obtain a polarization curve for a fuel cell (two electrodes in HCl). From what I've seen in literatures, current is applied and the voltage is measured. Is it still the same to change the voltage and measure the current instead? For some reason our equipment only have the voltage sweep option.

Thanks in advance!
 
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No, these would be different methods, requiring different hardware.

I admit that's the first time I hear about the "force current, measure voltage" approach. All electrochemical methods I have ever used were variants of voltammetry (vary potential, measure current). From what you wrote voltammetric methods are what your equipment is capable of.
 
Are you sure it is "current applied" and not "current drawn"?

Voltage drop under load is an important characteristics of any (chemical) battery.
 

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