Fast electrochemical impedance spectroscopy of lithium-ion batteries based on the large square wave excitation signal

Summary: Electrochemical impedance spectroscopy (EIS) is a technique for electrochemical characterization that is sensitive to the battery state and can uncover multidimensional electrochemical evolution information within the battery. Lithium-ion batteries usually need to be used in conjunction with power conversion circuits, while conventional EIS testing is conducted offline and is time-consuming, which cannot effectively monitor the battery characteristics during use. To match the characteristics of the square wave signal during power switching, a rapid EIS measurement method for lithium-ion batteries based on the large square wave excitation signal is proposed in this paper, and develops a testing device with a response time of microseconds. The proposed method and device are applied to estimate the state of health (SOH) of the battery. In conclusion, we proposed method enhances the capabilities of EIS testing technology and has a good application prospect in real-time online impedance monitoring.