Selective recovery of valuable metals from spent Li-ion batteries using solvent-impregnated resins

Abstract

Selective recovery of valuable metals (Cu²⁺, Co²⁺ and Li⁺) from leachate of spent lithium-ion (Li-ion) batteries was investigated in acidic chloride media using solvent impregnated resins (SIRs). An SIR containing bis(2-ethylhexyl) phosphoric acid (D2EHPA) had high selectivity for Fe³⁺ and Al³⁺, with an order of selectivity Fe³⁺ > Al³⁺ > Cu²⁺ > Co²⁺. Fe³⁺ and Al³⁺ could be removed from synthetic leachate by precipitation, followed by column adsorption with the SIR containing D2EHPA. The synthetic leachate was then applied to chromatography for selective recovery of Cu²⁺, Co²⁺ and Li⁺. The solution was first fed upward to a column packed with an SIR containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) for selective separation of Cu²⁺, followed by upward feed to another column packed with an SIR comprising PC-88A and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) for selective recovery of Co²⁺. Finally, a column packed with a synergistic SIR containing both 1-phenyl-1,3-tetradecanedione (C₁₁phβDK) and tri-n-octylphosphine oxide (TOPO) was used for selective recovery of Li⁺. A process flowsheet is proposed for selective recovery of Cu²⁺, Co²⁺ and Li⁺ using several SIRs. This process was found to be simple and efficient for selective recovery of valuable metals from leachate of spent Li-ion batteries. Pure copper, cobalt and lithium products were obtained, with high elution yields.

Keywords:

• Li-ion battery
• adsorption
• recovery
• solvent impregnated resins
• PC-88A
• Cyanex 272

Acknowledgements

We are grateful for financial support through a Grant-in-Aid for Scientific Research (No. K2127, K22091 and K2340) from the Ministry of Environment of Japan.