Early-Stage Recovery of Lithium from Lithium-Ion Battery Black Mass in Pilot Scale Using Supercritical CO2

Lithium-ion batteries (LIBs) are essential for meeting modern society’s energy needs, especially in the context of energy transition and e-mobility. The European Battery Regulation establishes strict recycling targets that require the efficient recovery of lithium (Li) from spent LIBs. This study focuses on the COOL process, a hydrometallurgical method that uses supercritical CO2 and water to selectively leach Li from the LIB black mass. Characterized by low chemical consumption and environmental friendliness, the COOL process has been successfully scaled from the laboratory to the pilot stage using a 200 L autoclave. This allowed leaching in the kg range instead of the usual leaching quantities of black mass in the gram range. This process achieves up to 97% Li leaching at 250 °C and 100 bar. The Li2CO3 obtained was successfully separated from the LiF present in the black mass, co-leached Al, Mn, Co and Ni as well as the Na2SO4 originating from the electrodialytic enrichment. A crude product with a purity >99.82% was obtained, which is battery grade quality and requires no further refining. The results underscore the importance of minimal thermal pretreatment and demonstrate that reusing Li-containing byproduct streams for black mass leaching does not hinder Li carbonatization, rendering Li recovery economically viable. This work significantly advances the COOL process, opening the way for its industrial application and compliance with European recycling regulations.