Potential versus current density

Graphs of operating potential versus current density are called polarization curves, which reflect the degree of perfection that any particular fuel cell technology has attained. High cell operating potentials are the result of many years of materials optimization. Actual polarization curves will be shown below for several types of fuel cell. 

Polarization probes rely on the relationship of the applied potential to the output current per unit area (current density). The slope of applied potential versus current density extrapolated through the origin, yields the polarization resistance Rp, which can be related to the corrosion rate. 

ASTM G59, Standard Prac tice for Conducting Potentiodynamic Polarization Resistance Measurements, provides instructions for the graphical plotting of data (from tests conducted using the above-noted ASTM Standard G103) as the hnear potential versus current density, from which the polarization resistance can be found. 

FIGURE 11.6 Anodic potential versus current density polarization curve (from Ref. 20). 

FIGURE 27.60 (A) Cell potential versus current density of recast Nation control. Nation 115 control, 10% silicon oxide/recast Nation, and... 

Figure 9 Potential versus current density (a) and power density versus current density (b) curves for two different anodes (PAni/Pt-Ru and PAni/Pt-Ru-Mo) in a direct methanol fuel cell (cell temperature 110°C 2 bar O2 pressure, and lOOmLmn gas flow 2M methanol aqueous solution at 2mLmn liquid flow).

Figure 7.56 Determination of the anodic (pa) and cathodic (Pc) Tafel slopes from the potential versus current density plot obtained by potentiodynamic polarisation testing.

Table 7.6 Characteristic corrosion parameters obtained from the potential versus current density plots shown in Figures 7.58 and 7.59.

Fig. 14 a Schematic cell configuration of redox flow cell at discharge mode. AQDSH2 refers to the reduced fram of AQDS. b Cell potential versus current density at five different states of charge, c Galvanic power density versus current density for the same SOCs. d Electrolytic powta-density versus current density. Reprinted from Ref. [170] with permission from Macmillan Publishers... 

Using total kinetics, plot the ORR over potential versus current density for a PEFC with a PT-C catalyst at 300 K, 1 atm for roughness factors of 1 (smooth electrode), 500, and 2000. 

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