Electro-Thermal Behaviour of Large Size Li-Ion Batteries from End of Life EV Module

Li-ion batteries (LiBs) reach the end of life (EOL) in electric vehicles (EV) application when their capacity reaches 80% of nominal value. However, there is plenty of energy and power remaining in them, which can be used in second-life applications. The suitability of EOL EVbatteries for second-life applications needs to be carefully investigated. For instance, the state of charge (SOC), state of health (SOH), and thermal behaviour during ageing need to be accurately assessed before implementation in the second-life application, otherwise, the
second-life system performance would suffer. Moreover, the variation of voltage and current density during cycling lead to a non-uniform temperature distribution, degradation and imbalanced ageing. A clear understanding of these degradations is also essential to achieve the full potential of EOL EV-batteries in the second-life applications.
In this study, the electro-thermal behaviour of EOL Nissan Leaf battery pack is investigated. Four EOL batteries (LMO chemistry and an initial capacity of 33Ah) from the same Nissan Leaf battery module are used in this study. Batteries arrangement in the module is shown in Fig. 1 (a) and to establish the connection in the module, tabs were cut and their active connection width was 1/4 of full tab width.