Development of the low-cost impedance spectroscopy system for modeling the electrochemical power sources

This paper presents a low-cost impedance spectroscopy system (LCISS) suitable for modeling the electrochemical power sources such as fuel cells, batteries and supercapacitors. Since the developed LCISS is composed of simple sensor circuits, commercial data acquisition board and software, it provides a low cost solution for modeling and diagnosing the electrochemical power sources compared with the commercial electrochemical impedance spectroscopy instruments. The system is capable of automatically measuring the impedance of the electrochemical power sources over the specified frequency range and from the measured impedance data an equivalent circuit can be derived by the developed software. In the proposed system, the digital lock-in amplification technique is adopted to achieve the accurate measurements even in the presence of the high level of noises. The validity of the developed system is proven by comparing the measured frequency response of a simple R-C filter with those obtained by using the commercial frequency response analyzer (NF FRA 5097). The developed hardware and software is applied to measure the impedance spectrum of the 1.2 kW proton exchange membrane fuel cell and the results are detailed.