Fig. 4(a), the first part in the equivalent circuit model includes a
series connection of resistance (R1) and inductance (L1), in parallel
with charge transfer resistance (Rct,1), and the constant phase
element (CPE1). The second part in the equivalent circuit model
includes charge transfer resistance (Rct,2) in parallel connection
with the constant phase element (CPE2). The corresponding
impedance parameters are shown in Table 3.
The polarisation resistance (Rp) can be obtained as the
following: