Self-driven aldol condensation enabling high-purity Li2CO3 recovery from spent lithium metal anodes

Abstract

Rechargeable lithium (Li)-metal batteries with high energy densities are approaching large-scale commercialization but face challenges in recycling due to the high reactivity of spent Li-metal anodes (S-LMAs). Here, we propose a recovery strategy using commercial acetone containing <1.00 wt % water. Sub-percent water first reacts with S-LMA to form LiOH, which consumes Li dendrites and mitigates safety risks. Then, LiOH catalyzes acetone aldol condensation to low-concentration diacetone alcohol (DAA, <5 mol %), which further reacts with S-LMA at acceptable rates and simultaneously drives the DAA production, thus achieving complete conversion of S-LMA. This approach yields high-purity Li₂CO₃ (99.79 wt %), surpassing the battery-grade standard (99.50 wt %). The recovered Li₂CO₃ enables the synthesis of LiNi_0.6Mn_0.2Co_0.2O₂ cathodes with electrochemical performance comparable to those from commercial Li₂CO₃. Combining safety, scalability, and economic viability, this method provides a practical route for recycling rechargeable Li-metal batteries and offers insights for extending to other alkali-metal-based batteries.