I tried parameterizing an ECM model with an EIS experimental data set using Matlab lsqcurvefit solver.
The resulting EIS is in an acceptable range if you see the attached figures. But my doubt is, the parameters seem erroneous with the physical meaning of it, which came as complex numbers as mentioned below.
Estimated Rs: 0.025413-0.0014315i
Estimated Rp: 0.0059842+0.00029675i
Estimated Rp2: 0.0084706-0.0064812i
Estimated C1: 1.5673-3.6365i
Estimated C2: 622.50351-879.48651i
Estimated C3: -382692.0319-230519.3501i
Estimated n: -0.83909+0.22546i
If anyone can please comment on this.
I appreciate your support.