(Digital Presentation) Reusing Li-Ion Batteries in Second-Life Applications: Impact of Cell Orientation in Electric Vehicle Pack

Li-ion batteries (LiBs) in electric vehicles (EVs) finish their life with a significant amount of capacity left in them (about 80% of the nominal capacity), which provides a promising avenue for reusing the spent EV-batteries in less demanding second-life applications, such as grid-scale energy storage for peak shaving, EV charging, storage for intermittent energy sources (solar or wind power), backup storage for industries and property owners, and less demanding vehicle propulsion (ferries or forklifts) [1, 2]. However, reusing spent EV batteries in second-life applications is not as straightforward as taking a battery pack from an EV then installing it directly into a second-life application. One must consider the state-of-health (SoH) of the battery packs and hence the modules and cells to avoid any mismatch in terms of capacity, state-of-charge/depth-of-discharge (SoC/DoD). Even within the batteries suitable for reuse, cells must be sorted by similar remaining capacity and identical degradation state, or else the second-life system performance would suffer. The SoH needs careful assessment and ageing conditions evaluated to send heavily degraded batteries to recycling facilities. Whilst assessing the SoH is straightforward [3], identifying the ageing condition is complex, as ageing and degradation of LiBs over time are caused by various factors, including charging/discharging rate (C-rate), operating temperature, lifetime, SoC, and cycling [2]. Moreover, pack design, configuration, cooling methods as well as cell/module's orientation in a pack can influence the battery degradation.