Effective separation of lithium isotopes (⁶Li and ⁷Li) is of great importance for the development of nuclear energy. Crown ethers (CEs) are widely used and reported separation systems, but the distribution coefficient of Li (D_Li) is relatively low by CEs (D_Li, 10⁻²–10⁻⁵) and mainly depends on the anion type of Li salt. Herein, a novel and facile ion-pair strategy by introducing tetrachloridoferrate ([FeCl₄]⁻) as counter anion is presented, which helps to overcome the Hofmeister bias and facilitates the efficient transfer of Li⁺ from extremely hydrophilic chlorides. An exceptionally high D_Li of 54 is achieved for benzo-15-crown-5 (B15C5), surpassing those of solvent extraction from solely Li salt aqueous solution. This strategy also demonstrates good separation performance of ⁶Li/⁷Li. The maximum ⁶Li/⁷Li separation factors (${\alpha }_{{}^6\mathrm{L}\mathrm{i}/{}^7\mathrm{L}\mathrm{i}}$) of 1.038 and 1.049 are obtained for B15C5 and benzo-12-crown-4 (B12C4) in dichloroethane at 273 K. The highly efficient phase transfer of Li⁺ can be attributed to the formation of stable [Li(B15C5)(H₂O)][FeCl₄] or [Li(B12C4)₂][FeCl₄] ion pairs. Theoretical studies based on density functional theory (DFT) calculations suggest that the coordination and electrostatic environment of Li⁺ plays an essential role in the separation of ⁶Li/⁷Li. Weakening the coordination and electrostatic interactions associated with Li⁺ can facilitate the separation of ⁶Li/⁷Li. Additionally, B15C5 can be easily recycled by using ultra-pure water as the stripping solution. This work provides an industrially promising system for ⁶Li/⁷Li separation.

锂同位素（⁶ Li和⁷ Li）的有效分离对核能的发展具有重要意义。冠醚 (CEs) 是广泛使用和报道的分离系统，但CEs ( D _Li , 10 ^{- 2} –10 ^-5 )的 Li ( D _Li )分配系数相对较低，主要取决于锂盐的阴离子类型. 在此，通过引入四氯化铁（[FeCl ₄ ] ^-）作为抗衡阴离子，提出了一种新颖且简便的离子对策略，这有助于克服 Hofmeister 偏差并促进 Li ⁺的有效转移。来自极亲水的氯化物。苯并 15-冠 5 (B15C5) 的D _Li达到了 54的异常高，超过了仅从锂盐水溶液中溶剂萃取的结果。该策略还展示了⁶ Li/ ⁷ Li 的良好分离性能。最大⁶ Li/ ⁷ Li 分离因子 (${\alpha }_{{}^6\mathrm{升}\mathrm{一世}/{}^7\mathrm{升}\mathrm{一世}}$B15C5 和 benzo-12-crown-4 (B12C4) 在 273 K 的二氯乙烷中获得 1.038 和 1.049 的 )。 Li ^{+ 的}高效相转移可归因于稳定 [Li(B15C5)(H ₂ O)][FeCl ₄ ] 或 [Li(B12C4) ₂ ][FeCl ₄ ] 离子对。基于密度泛函理论 (DFT) 计算的理论研究表明，Li ⁺的配位和静电环境在⁶ Li/ ⁷ Li的分离中起着至关重要的作用。减弱与 Li ⁺相关的配位和静电相互作用可以促进⁶ Li/ ⁷的分离李。此外，B15C5 可以通过使用超纯水作为汽提液轻松回收。这项工作为⁶ Li/ ⁷ Li 分离提供了一个具有工业前景的系统。