A Systematic Identification of First to Second Life Shift-Point of Lithium-Ion Batteries

Although the batteries used in electric vehicles usually have a vehicle lifetime of 8-10 years, after this period they may still have significant capacity left for alternative uses. The secondary use of hybrid/electric vehicle batteries increases the overall value and provides opportunities for the use in charging stations, renewable energy integration and grid energy management. The application life of a Lithium-ion traction battery can be split into first and second lives. The optimum point to switch the battery from first to second life is the shift-point of a Lithium ion battery. This paper proposes an approach to identify the shift-point by classifying the battery as a system with its own structural and behavioral properties. These are inter-related by the factors such as ageing, environment and costs. By structuring and analyzing these factors for automotive and stationary applications, the intention is to identify the optimum shift point of a traction battery during its lifetime. The analysis suggests that the cost factor gets the highest priority while the ageing and environment has the moderate and least priorities respectively.