Closed-Loop Lithium Recovery from LiFePO₄ Batteries Using Tartaric Acid Leaching

This study investigates the sustainable recovery of lithium from spent LiFePO4 batteries using tartaric acid derived from agro-food waste. To optimize both leaching and recovery processes, a fractional factorial design was first used to identify the key factors, followed by a central composite design for the process optimization. The optimal conditions, 2.1 M tartaric acid and a solid-liquid ratio of 110 g/L, achieved a lithium leaching efficiency of 95.0% (±2.3). The recovery of tartaric acid for reuse in multiple cycles was also optimized. Validation with real leaching solutions consistently demonstrated high recovery efficiencies with 98.0% (±1.9) of calcium tartrate and 97.7% (±3.6) of lithium phosphate. This study highlights the effectiveness of tartaric acid from agri-food waste for lithium leaching, promoting resource sustainability, and aligning with green chemistry principles. The findings provide a viable and efficient solution for industrial lithium recovery applications.