Avaliable methods of research
Electrode polarization measurements
The available setups make it possible to study polarization resistance and overpotential-current dependencies of individual electrodes
in the so-called half-cells, to assess power density and overall current-voltage dependencies of model SOFCs, to analyze kinetics
of electrochemical reactions in various electrode systems, and to evaluate long-term stability of the electrodes, solid electrolytes
and electrochemical cells.
For the model half-cells, the technique involves current (potential) scanning combined with impedance spectroscopy.
The measurements are carried out in the 3-electrode cells with working (WE), counter (CE) and reference (RE) electrodes.
The solid electrolyte membrane separates two chambers where oxygen, air, nitrogen, hydrogen or their mixtures can be supplied;
the oxygen partial pressure over WE is continuously controlled by an electrochemical sensor. If necessary, the gas mixtures may be dried
or humidified prior to entering the chamber.
The impedance measurements enable to separate Ohmic losses associated with the resistivity of the electrochemical cell components from
the polarization losses resultant from slow kinetics of the electrode processes:
The electrode overpotential under a given current can be extracted:
h = U - IROhm
is the potential difference between the WE and RE, I
is the current flowing between WE and CE, and IROhm
is the ohmic contribution
to the total potential drop.