Study and modeling of internal resistance of Li-Ion battery with change in temperature & SoC

Electric Vehicles (EVs) are the future of new way of transportation where the study of different batteries plays a vital role. Lithium-ion batteries (LiBs) are the most extensively researched and utilized rechargeable battery technology in EVs because of its properties like high power density, high energy density, low maintenance, and extended lifespan. It is understood from several studies that internal resistance places a vital role in the Battery Management System (BMS) of EVs. As a result, many scientists and researchers are placing more emphasis on monitoring internal resistance as a function of temperature and State of charge (SoC) for the purpose of designing BMS that is effective and trustworthy. In this paper, the change in internal resistance with different temperature and SoC condition are studied in control environment. It is noted that the internal resistance gradually increases with the increasing temperature which leads to localized heating in the battery pack. It is also observed that the internal resistance gradually decreases with decreases in depth of discharge (DoD) or increase in SoC which is important to identify the boundary operating conditions of a battery. The above studies have been done by using an Electrochemical impedance Spectroscopy (EIS) in an environmentally controlled cell. The above study helps to understand the dynamics of internal resistance of batteries in EVs at different temperature and SoC and also helps to design an efficient and reliable BMS for EV industries.