I have the impression that EIS is extremely sensitive to 'parasitic effects'. Not long ago, I spent time investigating the ionic conductivity of a solid-state electrolyte and encountered all the issues you described. My sample's impedance was on the order of a few GΩ, and I apparently had high contact resistance as well. I played with the setup parameters and could get those typical dome and tail shapes, but they were random with no clear trend, sometimes just noise, and most of the time no trend at all.

I got in touch with the manufacturer, and they mentioned something about a Faraday cage and a lock-in amplifier. Perhaps you may want to have a look into this.

Best of luck,

Gabriel Vinicius

Thanks a lot, Gabriel Vinicius, for your detailed response. It’s very reassuring to know others have faced similar issues with solid-state electrolyte systems.

You mentioned a Faraday cage and a lock-in amplifier I’ve heard these terms before, but I’m not fully familiar with their roles in EIS measurements, especially for high-impedance systems like mine (in the GΩ range).

Could you please explain briefly:

• What exactly is a Faraday cage and how does it help in EIS?
• What is a lock-in amplifier and how is it different from a normal potentiostat?
• Are there any resources, articles, or manufacturer recommendations you can share to help me implement these properly?

It seems like parasitic noise and setup sensitivity are real issues in my case too. Any practical advice on shielding and improving measurement quality would be very helpful.

Thanks again!

Anila Polai no big deal, glad to help!

Well, a Faraday cage could be any grounded metal 'box', such cages block external electromagnetic interference from reaching whatever is in it; the EIS setup, in your case. My understanding is that EIS typically applies tiny AC signals, which can be easily overwhelmed by external noise like fluorescent lighting, mobile phones, or any other electronics in the surroundings. So, a Faraday cage shields your measurement setup.

As for the lock-in amplifier, it is an instrument that can distinguish signals with a known frequency and phase from a noisy background; it kind of boosts the signal-to-noise ratio, resulting in noise-free outcomes (ideally, what you're looking for).

BTW, I haven't tried either of them, as knowing the ionic conductivity wasn't my priority at the time, so I let it go

Hope that helps,

Best,

Gabriel Vinicius