High-Frequency Electrochemical Impedance Spectroscopy to Measure Capacitive Behavior Related to Dielectric Property of Electrolyte of Lithium-Ion Batteries

Abstract Electrochemical impedance measurements in the high-frequency band above 1 MHz are significantly affected by parasitic inductance and capacitance originating from the measurement wirings. In impedance spectra of lithium-ion batteries (LIBs), inductive behavior typically appears in the high-frequency band, which often obscures signals originating from the sample itself. In this study, a measurement system was designed to suppress these parasitic components, and impedance measurements were performed over a frequency range of 20 Hz to 120 MHz for lithium-ion batteries with a sulfolane-based concentrated electrolyte. As a result, a capacitive semicircle was successfully observed in the Nyquist plot of the impedance spectrum at frequencies up to 103 MHz. The time constant of this capacitive semicircle originates from the relative permittivity and resistivity of the electrolyte.