Optimizing waste management to improve the process for producing battery-grade LiOH·H₂O from industrial-grade Li₂CO₃

Battery-grade lithium hydroxide monohydrate (LiOH·H₂O) is critical for lithium-ion batteries, yet its conventional causticization production faces sustainability challenges regarding waste management. This work systematically investigated the leaching kinetics and controlling mechanisms of lithium (Li) from lithium carbonate (Li₂CO₃) during causticization. The leaching behavior was found to follow the Avrami diffusion-controlled model, exhibiting a fast initial reaction rate with an apparent activation energy of 7.35 kJ⋅mol^-1. The leaching of Li was limited by the heterogeneous nucleation of calcium carbonate (CaCO₃) on Li₂CO₃ particles. An optimized strategy (CP-R) was proposed in this study, which involves calcining CaCO₃ precipitate to recover quicklime with a purity of 96.29%, and utilizing the Li₂CO₃ covered by the dense layer in the precipitate as additive for causticization, thereby achieving a closed-loop cycle of Li and Ca. Comprehensive economic analysis and life cycle assessment demonstrate that CP-R offers higher profitability and lower environmental impact compared to conventional causticization and electrodialysis bipolar membrane process. Overall, CP-R presents a compelling alternative for LiOH production by simultaneously addressing solid waste disposal and enabling closed-loop Li recycling.