In order to measure the small signal impedance of a device including the electrochemical devices as a function of frequency, you have to:

- Bias the device at the required DC operating point

- Then apply on it small sinusoidal signal voltage with the required frequency and connect a small ohmic series resistance to sense the ac current in the devices.

You need a difference amplifier to measure the voltage across the device and an amplifier to amplify the voltage across the current sensing resistance.

You can then acquire theses voltages to acquire the voltage across the device and the current passing through it , You can get the peak values and the phase between the two signals the voltage and the current. Then one calculates mag z and the phase of z.

I would like that you review the the two papers:

Article A distributed SPICE-model of a solar cell

and the paper:Article Four Voltmeter Vector Impedance Meter Based on Virtual Instrumentation

Best wishes

You may use Analog Devices AD5933 chip along with Arduino. But it has its limitations.