Li-ion batteries life cycle from electric vehicles to energy storage

Vehicle electrification is an emerging solution to reduce fossil fuel dependence and the environmental pollution caused by automobile emissions. Electric vehicles (EVs) are powered by Li-ion batteries which degrade with use and time, and once their state of health (SOH, ratio of current capacity to the initial capacity) reaches 80% they retire from the EVs and need a replacement. In this study, battery degradation behaviour has been investigated and demonstrated under different electrical and thermal loading conditions. A different rate of cell degradation has been observed with different environmental and electrical loading conditions. The rate of degradation of the cells is higher at low temperatures and at high current charging conditions. Additionally, it has been demonstrated that the temperature of the cells within a battery module is different across the 6S2P battery module which would be significantly higher in the case of a bigger battery module. Hence for the potential second-life applications of the retired electric vehicle batteries, knowing the correct cell SOH is highly essential to grouping them which will lead to optimized use of this battery in 2nd life applications.