Principles and Applications of Electrochemical Impedance Spectroscopy (EIS) Technology in Battery Testing

Overview of Electrochemical Impedance Spectroscopy Technology

Electrochemical impedance spectroscopy (EIS), as an advanced electrochemical characterization technique, plays an irreplaceable role in modern battery testing. This technology applies a small alternating current signal to the tested battery and measures its response to obtain the complex impedance characteristics within the battery. Compared with traditional direct current testing methods, EIS has significant advantages such as non-destructiveness and high sensitivity, making it particularly suitable for studying the kinetics of electrochemical reactions inside batteries.

In today's rapidly developing lithium-ion battery (LIB) technology, the application value of EIS is increasingly prominent. As energy density and power density continue to rise, battery impedance has dropped to extremely low levels (typically on the micro-ohm scale), posing unprecedented challenges for measurement techniques. Modern EIS systems can accurately measure impedance changes down to μΩ levels across a wide frequency range from 1 mHz to 10 MHz, providing powerful tools for battery research and quality control.

From Dielectric Spectroscopy to Electrochemical Impedance Spectroscopy

To deeply understand the principles of EIS technology, it is necessary to start from more fundamental material electrical characterization methods—dielectric spectroscopy. Dielectric spectroscopy primarily studies materials' electrical properties at high frequencies (MHz to GHz range), including dielectric constant (characterizing energy storage capacity) and conductivity (characterizing charge transport capability). These two parameters together form the complex dielectric constant ε*=ε'-jε