The Mg²⁺/Li⁺ screening selectivity determines the practical application of nanofiltration technology in lithium extraction from salt-lake brines and industrial lithium production. In this work, a membrane structure design strategy based on the interlayers was developed to prepare nanofiltration (NF) membranes with high Mg²⁺/Li⁺ separation selectivity and high permeability. Through investigating the influence of the interlayer charge on the structure and performance of the NF membrane, the interlayer for the preparation of the NF membrane with high Mg²⁺/Li ⁺ separation selectivity was screened. Relevant characterizations indicate that the positively charged interlayer can endow the NF membrane with appropriate pore size and surface charge density to achieve high Mg²⁺/Li⁺ separation selectivity through the synergistic effect of size sieving and Donnan exclusion. Moreover, the pore size of the NF membrane is controlled by the release rate of the piperazine (PIP) from the interlayer, while the surface charge density of the NF membrane is jointly determined by the charge of the interlayer and PA layer. The performance evaluation suggests that the NF membrane prepared with the best screened interlayer has a Mg²⁺/Li⁺ separation factor up to 88.6 while maintaining a high permeability (22.5 L m⁻² h⁻¹·bar⁻¹), which is better than that of the most membranes reported in the literature. Overall, this work is expected to promote the practical application of NF membranes in lithium extraction from salt-lake brines and industrial lithium production.

Mg ²⁺ /Li ^{+筛选选择性决定了纳滤}技术在盐湖卤水提锂和工业锂生产中的实际应用。在这项工作中，开发了一种基于中间层的膜结构设计策略来制备具有高Mg ²⁺ /Li ⁺分离选择性和高渗透性的纳滤（NF）膜。通过考察层间电荷对纳滤膜结构和性能的影响，制备高Mg ²⁺ /Li  ^{+纳滤膜的层间层} 筛选分离选择性。相关表征表明，带正电的中间层可以赋予纳滤膜适当的孔径和表面电荷密度，通过尺寸筛分和唐南排除的协同作用实现高Mg ²⁺ /Li ⁺分离选择性。此外，NF膜的孔径大小由中间层哌嗪（PIP）的释放速率控制，而NF膜的表面电荷密度由中间层和PA层的电荷共同决定。性能评估表明，采用最佳筛选夹层制备的纳滤膜的Mg ²⁺ /Li ⁺分离因子高达88.6，同时保持高渗透率（22.5 L m^-2  h ^-1 ·bar ^-1 )，这比文献中报道的大多数膜都要好。总体而言，这项工作有望促进纳滤膜在盐湖卤水提锂和工业锂生产中的实际应用。