The global market of lithium-ion batteries (LIB) has been growing in recent years, mainly owed to electromobility. The global LIB market is forecasted to amount to $129.3 billion in 2027. Considering the global reserves needed to produce these batteries and their limited lifetime, efficient recycling processes for secondary sources are mandatory. A selective process for Li recycling from LIB black mass is described. Depending on the process parameters Li was recovered almost quantitatively by the COOL-Process making use of the selective leaching properties of supercritical CO2/water. Optimization of this direct carbonization process was carried out by a design of experiments (DOE) using a 33 Box-Behnken design. Optimal reaction conditions were 230 °C, 4 h, and a water:black mass ratio of 90 mL/g, yielding 98.6 ± 0.19 wt.% Li. Almost quantitative yield (99.05 ± 0.64 wt.%), yet at the expense of higher energy consumption, was obtained with 230 °C, 4 h, and a water:black mass ratio of 120 mL/g. Mainly Li and Al were mobilized, which allows for selectively precipitating Li2CO3 in battery grade-quality (>99.8 wt.%) without the need for further refining. Valuable metals, such as Co, Cu, Fe, Ni, and Mn, remained in the solid residue (97.7 wt.%), from where they are recovered by established processes. Housing materials were separated mechanically, thus recycling LIB without residues. This holistic zero waste-approach allows for recovering the critical raw material Li from both primary and secondary sources.

Lithium is a key element in reducing mobility-induced emissions. However, processes aimed at producing lithium from hard rock mining are based on the usage of large amounts of chemicals. Additionally, only a small quantity of the mined mineral concentrates is actually valorized. In contrast, the COOL process (CO2 Leaching process) is a process that makes use of water and carbon dioxide to leach lithium from any silicate mineral, making geopolymers from the residues. On the other hand, the COOL process enables the recovery of lithium from pretreated spent lithium-ion batteries.The leaching step has been investigated concerning the selective mobilization of lithium. Further attention was brought to the mobilization of potentially disturbing ions such as fluoride, aluminum, and silicon.It was found that the CO2 leaching step is indeed suitable for the selective mobilization of lithium. Up to 65% of lithium mobilization was achieved without adding any additives and 78% by adding Na2CO3. Fluoride and silicon mobilization could be addressed by heating zinnwaldite under a wet atmosphere respectively under the addition of a carbonate. Concerning secondary resources, up to 95% of lithium could be leached from black mass, and the residue was then leached and the leach liquor separated by liquid-liquid extraction to yield the heavy metals in high recovery and selectivity.Overall, the COOL process enables the recovery of lithium from different feedstocks and valorizes the residues from the lithium leaching. This makes the COOL process a universal approach to lithium recovery. Graphical Abstract

Lithium is a key element in reducing mobility-induced emissions. However, processes aimed at producing lithium from hard rock mining are based on the usage of large amounts of chemicals. Additionally, only a small quantity of the mined mineral concentrates is actually valorized. In contrast, the COOL process (CO2 Leaching process) is a process that makes use of water and carbon dioxide to leach lithium from any silicate mineral, making geopolymers from the residues. On the other hand, the COOL process enables the recovery of lithium from pretreated spent lithium-ion batteries.The leaching step has been investigated concerning the selective mobilization of lithium. Further attention was brought to the mobilization of potentially disturbing ions such as fluoride, aluminum, and silicon. It was found that the CO2 leaching step is indeed suitable for the selective mobilization of lithium. Up to 65 % of lithium mobilization was achieved without adding any additives and 78 % by adding Na2CO3. Fluoride and silicon mobilization could be addressed by heating zinnwaldite under a wet atmosphere respectively under the addition of a carbonate. Concerning secondary resources, up to 95 % of lithium could be leached from black mass, and the residue was then leached and the leach liquor separated by liquid-liquid extraction to yield the heavy metals in high recovery and selectivity. Overall, the COOL process enables the recovery of lithium from different feedstocks and valorizes the residues from the lithium leaching. This makes the COOL process a universal approach to lithium recovery.