Technoeconomic decision support for second-life batteries

The growth of electric vehicles (EVs) has raised concerns about the disposition of their batteries once they reach the end of their life. Currently, recycling is regarded as the potential solution for retired Li-ion batteries (LIBs). However, these LIBs can still 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 recycle them. Here, a technoeconomic decision support model is proposed to evaluate retired batteries from both technical and economic perspectives. Data-driven models are developed and combined with an equivalent circuit model (ECM) to build module-level aging models. Simulations show that limiting the State of Charge (SOC) operating range and charge current in second life applications can extend the lifetime of LIBs. Depending on when and how to use the battery in its second life, the simulated lifetime is between 1–6 years. From an economic perspective, the most profitable application is frequency regulation, which has a value of $\$$/kWh. A comprehensive comparison of different end-of-life strategies is presented to demonstrate the most economically way to handle a retired battery.