A Decision-Making Model for Retired Li-Ion Batteries

Abstract

The growth of electric vehicles (EVs) has raised concerns about the disposition of their batteriesonce they reach their end of life. Currently, recycling is regarded as the potential solution forretired Li-ion batteries (LIBs). However, these LIBs still retain around 80% of their originalcapacity, which can be repurposed for other energy storage system (ESS) applications in their"second life" before recycling. Yet, there is no guidance for deciding whether to reuse or recyclethem. Here, we propose developing a decision-making model that evaluates retired batteriesfrom both technical and economic perspectives. We develop data-driven models and combinethem with an equivalent circuit model (ECM) to build module-level aging models. Simulationsshow that limiting the State of Charge (SOC) operating range and charge current in second lifeapplications can extend the lifetime of LIBs. Upon when and how to use the battery in secondlife, the simulated lifetime is between 1-6 years. From an economic perspective, we find that themost profitable application is frequency regulation, which has a value of 273.4$ 𝑘𝑊 ℎ −1 . Wepresent a comprehensive comparison of different end-of-life strategies to demonstrate the mosteconomically way to handle a retired battery.

Keywords: Second life batteryDecision-making modelData-driven modelModule-level aging model