The State of Arts and Development Trend of SOH Estimation for Lithium-ion Batteries

State of health (SOH) estimation for Lithium-ion batteries is a core technology of battery management systems, which is a foundation of ensuring system's safety and reliability. An accurate SOH estimation reflects the present fraction of allowable performance left before the end of life. In this paper, quantization standards of SOH are introduced firstly and some suggestions are proposed to solve the inconformity issue of SOH definitions. Then the battery aging phenomenon is interpreted theoretically, which contains the analyses of the aging mechanism, the changes of parameters during aging processes and the factors of accelerating aging. Next, some main methods of the SOH estimation are summarized and compared with each other. And finally, this paper describes the development trend of SOH estimation algorithm.