A Model for Local Impedance: Validation of the Model for Local Parameters Recovery from a Single Spectrum of PEM Fuel Cell

Abstract

A physics-based numerical model for fitting local impedance spectra (local impedance model, LIM) of the segmented PEM fuel cell is developed and used to validate our recent model for recovery of local parameters from a single spectrum of the whole cell (cell impedance model, CIM). Shapes of the local parameters along the cathode channel resulting from the two models are compared.Overall, the CIM quite satisfactorily describes the cell local parameters provided that the oxygen transport impedance in the channel is not small as compared to other impedances in the cell.

A Kernel for Calculating PEM Fuel Cell Distribution of Relaxation Times

“…where D is the oxygen diffusivity in the transport layer of the thickness l. Setting f W 35 Hz (Figure 5A) and l l t , for the oxygen diffusion coefficient in the CCL, we get D ox ≃ 1.2 • 10 -4 cm 2 s −1 , which agrees with measurements (Reshetenko and Kulikovsky, 2019). With the growth of cell current, the peak frequency f 3 rapidly shifts to 200 Hz (Figure 6C), corresponding to D ox ≃ 7 • 10 -4 cm 2 s −1 .…”

“…The impedance points in the frequency range above ≃ 10 3 Hz have been discarded due to effect of cable inductance. More details on experimental setup and measuring procedures can be found in Reshetenko and Kulikovsky (2019).…”

“…With the typical values of σ p ≃ 0.01 S cm −1 and C dl ≃ 20 F cm −3 [Ref. (Reshetenko and Kulikovsky, 2019)], we get f p ≃ 700 Hz, which by the order of magnitude agrees with the proton peak position in Figures 5A-C. The growth of f 4 with the cell current and the respective decay of the peak resistivity R 4 (Figure 6C) is due to growing amount of liquid water improving the CCL proton conductivity.…”

A kernel for PEM fuel cell distribution of relaxation times

“…With the typical values of σ p 0.01 S cm −1 and C dl 20 F cm −3 (Ref. 21 ) we get f p 700 Hz, which by the order of magnitude agrees with the proton peak position in Figures 5a-c. The growth of f 4 with the cell current and the respective decay of the peak resistivity R 4 (Figure 6c) is due to growing amount of liquid water improving the CCL proton conductivity.…”

“…The impedance points in the frequency range above 10 3 Hz have been discarded due to effect of cable inductance. More details on experimental setup and measuring procedures can be found in 21 .…”