Enhancing Second-Life Battery Storage Systems: An Improved Methodology for Soh Estimation and Cell Grading

Second-life battery storage systems offer a sustainable and cost-effective solution for extending the lifecycle of lithium-ion batteries while addressing the growing energy storage demands. Once removed from electric vehicles (EVs), these batteries retain sufficient capacity for secondary applications, such as stationary energy storage for renewable energy integration and grid stabilization. This research presents an improved CC-CCCV charging and discharging methodology, which enhances State of Health (SOH) estimation accuracy over the traditional CC-CV approach. Additionally, an optimized grading process is implemented to ensure uniform battery performance, improving efficiency and reliability. By repurposing EV batteries, this study promotes a circular economy, reducing electronic waste, minimizing resource consumption, and supporting clean energy solutions. The proposed approach contributes to long-term environmental sustainability by lowering the carbon footprint and enhancing energy resilience in various storage applications.