Design of a Low-Cost Frequency Response Analyzer for Electrochemical Impedance Spectroscopy

Abstract

This report presents a low-cost frequency responser analyzer (FRA) that can execute electrochemical impedance spectroscopy (EIS) at a lower cost than currently available tools. EIS is a mature, reliable and highly information-rich measurement technique that reveals numerous key properties of electrochemical systems. For decades, EIS has aided research in a myriad of fields from pharmaceuticals to fuel cells. Unfortanately, currently available EIS instrumentation costs thousands of dollars. This high cost has historically limited EIS to experimental laboratory applications. The FRA presented here, consisting of an off-the-shelf digital oscilloscope, costs less than $200.00 and therefore has potential to enable new EIS applications, as well as enormously benefit conventional applications in laboratory research. One potential new application upon which this report elaborates in detail is the balancing of battery cells in electric vehicles (EVs) to prolong battery pack lifetime, improve safety and increase EV driving range. In its current state, the proposed FRA is capable of perturbing an electrochemical system with an AC signal of prescribed frequency and amplitude and calculating the system’s impedance over a range of frequencies. More work is still needed to enable the FRA to perform a complete frequency sweep and calculate impedances more accurately.