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Conventional hydrometallurgy recycling process for treating wasted lithium-ion batteries (LIBs) typically results in the consumption of large amounts of corrosive leachates. Recent research on reusable leachate is expected to significantly improve the economic and environmental benefits, but is usually limited to specific and unique chemical reactions which could only apply to one type of metal elements. Herein, we report the co-extraction of multiple metal elements can be extracted without adding precipitates by mixed crystal co-precipitation, which enables the reusability of the leachate. We show that an oxalic acid (OA): choline chloride (ChCl): ethylene glycol (EG) type DES leachate system can leach transition metals from wasted LiNixCoyMn1-x-yO2(NCM) cathode materials with satisfactory efficiency (The time required for complete leaching at 120°C is 1.5 h). The transition metals were then efficiently extracted (with a recovery efficiency of over 96% for all elements) by directly adding water without precipitants. Noteworthy, the leachate can be efficiently recovered by directly evaporating the added water. The successful realization of reusability of leachate for the synergistic extraction of multiple elements relies on the regulation of the mixed crystal co-precipitation coefficient, which is realized by rationally design the reaction condition (composition of leachate, temperature and time) and induces the extraction of originally soluble manganese element. Our strategy is expected to be generally applicable and highly competent for industrial applications.

While hydrometallurgy is the primary technology for recycling spent lithium-ion batteries due to various advantages, it still involves substantial consumption of chemical reagents and poses challenges in wastewater emission. Herein, we report the realization of cathode recycling under lean-leachate conditions by dynamically stabilizing hole-mediated diffusion kinetics, which is enabled by synchronizing the extraction step during the leaching stage, thus continuously removing the dissolved ions out of the leachate. Theoretical molecular dynamics simulations predict that preventing the accumulation of the dissolved ions is efficient for keeping the leaching process proceeding. Experimentally, even with a small dosage of leachate (0.5 mL), a 94.51% leaching efficiency can be achieved (90 °C, 40 min) for spent LNO materials. Considering that our strategy is not limited to a specific materials system, it could be extended to recycle other valuable materials (including LCO or NCM 811) with minimal leachate usage.