With the in-depth advancement of the new energy industry, Li has become a core raw material for new energy vehicles and large-scale energy storage. Its market demand has skyrocketed. Around 70% of the world’s proven lithium resources are stored in salt-lake brines. Unlike overseas salt lakes with low Mg²⁺/Li⁺ ratios, most salt lakes feature complex water systems and an ultra-high Mg²⁺ ratio, with some areas recording a Mg²⁺/Li⁺ ratio as high as 1000:1. Since Mg²⁺ and Li⁺ share similar ionic radii, hydration energies and other physicochemical properties, they are extremely difficult to separate. Traditional techniques lead to lengthy purification workflows, high production costs and massive waste discharge, resulting in resource waste and environmental pressure, and greatly restricting the large-scale, low-cost and green development of domestic salt lake lithium resources. Traditional nanofiltration (NF) membranes are promising for Mg²⁺/Li⁺ separation due to their low energy consumption and easy operation. However, they are plagued by an Li + selectivity-permeability trade-off.
A team of bio-inspired material scientists led by Jingxin Meng from Chinese academy of sciences in Beijing, China drew inspiration from the precise ion transport mechanism of natural potassium ion channels and developed a biological ion channel-inspired nanofiltration (BICNF) membrane. By grafting positively charged quaternary ammonium groups onto negatively charged polyamide substrates, the team constructed a unique asymmetric "positive-outside, negative-inside" charge heterostructure. This design generates a distinctive electrostatic steering effect, which simultaneously enhance both Mg 2+ /Li + selectivity and Li + permeability, fundamentally resolving the trade-off of conventional membranes.
The team published their manuscript in Nano Research on August 20, 2026.
“This bioinspired charge engineering strategy successfully breaks the classic selectivity-permeability trade-off of nanofiltration membranes,” Jingxin Meng explained. “It overcomes the core limitation of traditional separation technologies and lowers the cost and environmental burden of lithium extraction from salt lakes.”
The team believes this work provides a scalable, high-efficiency approach for Li resource exploitation. In the next stage, they will optimize the membrane preparation process and conduct pilot tests with real salt-lake brines, striving to promote the industrial application of the BICNF membrane. Beyond lithium-magnesium separation, the asymmetric charge design also has great potential for other ion separation scenarios in water treatment and resource recycling.
Comprehensive performance tests prove the remarkable advantages of the BICNF membrane. It maintains a Mg²⁺ rejection rate above 98.5% and a Li⁺ rejection rate below 25%, presenting excellent monovalent/divalent ion sieving capacity. It achieves a Mg²⁺/Li⁺ separation selectivity of 75 and a Li⁺ permeability of 0.65 mol·m⁻²·h⁻¹, outperforming most commercial and lab-scale nanofiltration membranes reported to date. More importantly, the membrane retains stable separation performance when the Mg²⁺/Li⁺ ratio fluctuates from 1 to 1000, showing strong adaptability to complex water bodies of various salt lakes. After three-stage purification, the final lithium carbonate product reaches 99.1% in purity. This technology provides a reliable technical solution and theoretical support for the low-cost, high-efficiency industrial production of lithium from high-magnesium salt-lake brines.
The research team expects this bioinspired nanofiltration technology to spur development of next-generation high-performance ion separation membranes and advance the low-cost, green industrialization of Li extraction from high-magnesium salt lake brines. “Biological ion channel-inspired nanofiltration membranes are expected to achieve scalable production and broader engineering deployment in the coming years. Beyond Mg 2+ /Li + separation, this asymmetric charge engineering strategy also holds great potential in other ion separation scenarios including water purification, heavy metal recovery and industrial wastewater treatment,” said Jingxin Meng.
Other team members include Xipeng Li and Mengqi Yuan from Binzhou Institute of Technology. This research was supported by the National Natural Science Foundation of China and the start-up fund from Binzhou Institute of Technology.
DOI Link:
https://doi.org/10.26599/NR.2026.94908893
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
Nano Research
Breaking the Selectivity-Permeability Trade-Off: Potassium Channel-Inspired Composite Membrane Enables Efficient Mg²⁺/Li⁺ Separation
20-Aug-2026