Lithium recovery process from spent batteries

High-Purity Lithium Recovery from Spent Batteries Using Selective Complexing Precipitation and Nanofiltration

This technology is an integrated hybrid process that selectively precipitates and removes iron and aluminum as hydroxides by adding a complexing agent and a base to the acid leachate of spent lithium batteries, followed by treating the remaining aqueous solution with ultrafiltration and nanofiltration. This separates and concentrates lithium ions from multivalent metal ions to recover high-purity lithium.

Recycling spent lithium batteries has been challenging due to the lack of cost-effective technologies to separate the mixture of metal ions—such as lithium, iron, aluminum, nickel, cobalt, and manganese—found in acidic waste solutions. Conventional chemical precipitation methods often suffer from lithium loss during pH adjustment, generate large volumes of wastewater, and require expensive solvents, limiting their economic viability.

This technology uses a complexing agent, such as ammonium citrate, and a base to selectively precipitate iron and aluminum at a pH of 3.5 to 6.5. A nanofiltration membrane is then used to filter out over 60% of divalent valuable metal ions while allowing monovalent lithium ions to pass through. The recovered lithium solution is treated with carbonate to obtain lithium carbonate crystals, and any residual lithium is further recovered via reverse osmosis, forward osmosis, or membrane distillation. Applicable to hydrometallurgical plants for EV battery black mass and LFP battery recycling lines, this process keeps lithium loss below 30% while enabling the recovery of nickel, cobalt, and manganese as separate resources.

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Key Features:

• Acid-treating spent lithium batteries to provide an acidic lithium waste solution containing divalent ions of at least one of iron, nickel, cobalt, or manganese
• Adding a complexing agent and adjusting the pH to 3.5–6.5 with a base to precipitate iron as a hydroxide and form a first lithium-containing aqueous solution
• Forming a second lithium-ion-containing aqueous solution using a nanofiltration membrane with a divalent ion rejection rate of at least 60% and a monovalent ion rejection rate of 20% or less
• Recovering lithium from the second aqueous solution and recovering the divalent ions of valuable metals that did not pass through the nanofiltration membrane, either individually or as a mixture

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of new biodiesel production technology from lignocellulosic biomass using rapid pyrolysis and supercritical ethanol upgrading processes.

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