 Lithium ion batteries have high energy density and small size, making them popular for clean energy applications. Real-time monitoring of their state of health is important for ensuring safe operation. However, traditional monitoring methods based on voltage and current are limited in accuracy due to the complex aging process of lithium ion batteries. Electrochemical impedance spectroscopy, EIS, has emerged as a promising method for estimating battery health online by measuring impedance in a wide frequency range. This paper summarizes the latest EIS measurement technology and its application in lithium ion battery health state estimation, highlighting its advantages and limitations, and prospects for future development. This article was authored by Ming Zhang, Yan Zhuolu, Dijili, and others.