Impedance spectroscopy as a technique for monitoring aging effectsin nickel hydrogen and nickel-metal hydride batteries

摘要

Impedance spectroscopy is evaluated as a method for the earlydetection of aging effects in electrochemical cells. AC impedance andphase measurements were made on about 85 cells in various stages of lifetesting. Spectral data from 3 mHz to 30 kHz were acquired on fullydischarged cells. Impedance spectroscopy provided an effective means ofdetecting age diversity present in the test population. This could beseen in the data at very low frequencies, below 1 Hz. This is the socalled Warburg region where the availability of charge carriers isdiffusion controlled. Both raw impedance data and Argand diagrams, inwhich reactance is plotted as a function of resistance, represent usefulgraphical outputs