One-step selective recovery and cyclic utilization of valuable metals from spent lithium-ion batteries via low-temperature chlorination pyrolysis

An efficient and environmentally friendly closed loop process combing low-temperature chlorination pyrolysis with water leaching is proposed for one-step selective recovery and cyclic utilization of valuable metals from spent lithium-ion batteries (LIBs). First, the spent LiNi_xCo_yMn_zO₂ (s-NCM) cathode materials are pyrolyzed with NH₄Cl as a chlorination agent and the valuable metals (Ni, Co, Mn, Li) can be converted into readily soluble chloride which attribute to the release of HCl and NH₃ from NH₄Cl. After the s-NCM cathode materials treated via low-temperature chlorination pyrolysis at 300 °C for 30 min with NH₄Cl/s-NCM mass ratio of 3:1, more than 99.9% of the valuable metals can be recovered by simple water leaching. Moreover, thermodynamic analysis show that the valuable metals can be converted to chloride while the impurity metals (Fe, Al) do not participate in the reaction at this temperature, which can achieve the one-step selective recovery of valuable metals. Therefore, the water leaching solution can be directly used to synthesize regenerated pristine NCM (r-NCM) cathode materials which exhibit excellent cycle and rate performance. In summary, one-step selective leaching and regeneration of valuable metals can be accomplished by low-temperature chlorination pyrolysis. The whole process reduces the energy consumption and the environmental pollution caused by alleviating the introduction of acidic or alkaline chemicals and realize the high-value utilization of waste resources.