Characterization of a Novel Crown Ether System for Lithium Isotope Separation

6 Li and 7 Li, with excellent nuclear properties, are important raw materials in the development of the nuclear industry. In the current work, a mercury-free extraction and lithium isotopic separation system with benzo-15-crown-5 (B15C5) ether as the extractant, ionic liquid as the co-extractant, and anisole as the diluent was constructed. In addition, a novel method for extracting lithium ions with B15C5 and multistage cross-flow separation of lithium isotopes by the organic liquid film were introduced. After 20 stages of cross-flow extraction, the abundance of 6 Li increased from 7.498 to 9.654% and the abundance of 7 Li increased from 92.502 to 93.561%. It was demonstrated that the B15C5 system not only can enrich 6 Li but also can serve to enrich 7 Li. The reason for the enrichment of lithium isotopes by this method was explored. Moreover, this study predicted the number of theoretical cross-flow stages of the abundance of 6 Li and 7 Li which can be used as a nuclear material.