Investigation of Electrochemical Impedance Characteristics for Battery Health Diagnostics

Abstract

Battery degradation has been a major problem that impairs performance, safety, and operation life of the advanced energy storage systems especially in electric vehicles and grid-integrated systems. The correct calculation of the State of Health (SOH) is thus crucial to having proper control of the batteries as well as maximising their usage. Nevertheless, the traditional SOH estimation methods like coulomb counting and the voltage-based methods, tend to have a lesser degree of accuracy associated with the nonlinear dynamics of a battery, ageing, and varying environmental conditions which primarily contaminate the traditional SOH estimation methods. In this regard, this paper examines the electrochemical impedance behaviour of batteries through electrochemical impedance Spectroscopy (EIS) as a good non-invasive diagnostic method. The suggested methodology is an impedance measurement in a wide frequency range; estimation of the essential parameters, which are solution resistance, charge transfer resistance, and double-layer capacitance, by means of the equivalent circuit modelling. It is tested experimentally, as the parameters change as a result of various degradation conditions. These findings show that there is a high correlation between the impedance properties and battery health, where the resistance to charge transfer shows a steady rise throughout the degradation. Also, the capacitance changes can be used to gain information regarding the electrode ageing process. The results indicate that EIS-based analysis can contribute greatly to the accuracy and reliability of SOH estimation and thus should be considered in the future as an alternative to implement in other, more sophisticated, battery management systems that will run in real time.