I. Introduction
Lithium-ion batteries (LIBs) have been widely applied in fields such as electric vehicles (EVs), portable electronic devices and energy storage systems because of their advantages of long lifespan, low self-discharge, high energy density, and high output voltage [1], [2]. Due to various kinds of physical and chemical mechanisms, the performance of LIBs gradually deteriorates with increasing charge and discharge cycles [3]. If the battery state of health (SOH) cannot be monitored in real-time, it may reduce the performance of devices or even cause catastrophic events, such as explosions and fires [4]. Moreover, accurate SOH estimation is crucial for state of charge (SOC) estimation and fault diagnosis of battery systems [5]. To ensure the safe and efficient operation of LIBs, as well as to schedule timely maintenance plans, it is vitally important to give an accurate estimation of SOH.