jp6b11501_si_001.pdf (386.62 kB)
Method of the Four-Electrode Electrochemical Cell for the Characterization of Concentrated Binary Electrolytes: Theory and Application
journal contribution
posted on 2017-02-01, 00:00 authored by M. Farkhondeh, M. Pritzker, C. Delacourt, S. S.-W. Liu, M. FowlerA novel
method based on a four-electrode cell to determine the
transport properties of concentrated binary electrolytes is presented.
The cell contains two potential sensors in addition to the working
and counter electrodes. The sensors measure the closed-circuit as
well as the open-circuit potential in response to an input galvanostatic
pulse across the working and counter electrodes. An important advantage
of this new method is that it requires only the application of a single
pulse in addition to the appropriate concentration cell experiments.
By fitting a suitable model to the data obtained from these experiments,
the three independent transport properties of a concentrated binary
electrolyte and thermodynamic factor can be determined. The proposed
technique benefits considerably from the measurement of closed-circuit
data for estimation of the transference number. A comprehensive 2D
axisymmetric model based on concentrated-solution theory is developed
to account for faradaic convection as well as the bipolar effect at
the surface of the sensors. It is shown that the bipolar effect has
negligible impact on the potential measurements under operating conditions
relevant to these experiments. Consequently, a simpler 1D model can
be used in place of the 2D model to estimate the transport properties
without any loss in accuracy.