Rapid Analytical Instrumentation for Electrochemical Impedance Spectroscopy Measurements

This work reports a low-cost custom electrochemical instrument capable of performing rapid and accurate electrochemical impedance spectroscopy (EIS) for supercapacitors over a broad frequency band (10 mHz to 2 kHz). Conventionally, EIS is measured via sinusoidal perturbations; however, such an approach suffers from lengthy measurement time. Chirp signals have been shown previously to reduce EIS measurement time for supercapacitors for relative narrow frequency bands (1 Hz to 2 kHz). However, to characterize supercapacitors comprehensively, much broader frequency bands are required. Here, we present a custom instrument with an adaptive measurement algorithm for performing EIS measurements in a wide frequency range of 10 mHz to 2 kHz with low measurement uncertainties. The results obtained using this new technique has been validated here with a commercial instrument on several types of supercapacitors. Furthermore, measurement time on average decreases from 1500 s to less than 400 s. The overall cost of the custom instrument is 90% lower as compared to the commercial instrument. The custom instrument’s accuracy, time efficiency and low cost are expected to benefit electrochemical researchers.