A team of researchers says boron nitride nanotubes can move lithium ions about 31 times faster than expected while still screening out many other ions. That is the kind of result that can make battery engineers and desalination researchers sit up a little straighter, because it points to a membrane that is both fast and selective – a rare and annoyingly useful combination.
If the effect holds up outside controlled experiments, the same structure could help recover lithium more efficiently from brines and waste streams, or convert differences in salt concentration into usable electricity. That puts it in the same conversation as other ion-transport membranes now being developed for water treatment, energy harvesting, and materials recovery.
How the boron nitride nanotube membrane works
To test the idea, the researchers built a membrane from millions of charged nanotubes and placed it between salt solutions with different concentrations. They then measured ion transport across the setup and found that lithium moved far faster than theory predicted, while other ions were held back much more effectively. In other words: the membrane does not just let stuff through – it seems to have opinions.
That matters because membrane design usually forces a trade-off between speed and selectivity. Break that trade-off, even partially, and you have a path toward cheaper lithium extraction and more efficient electrochemical systems. Similar approaches have been explored with other nanostructured materials, but this result stands out because the measured transport was faster than expected by theory and faster than previously observed in similar systems, according to the researchers.
Lithium extraction and battery recycling
The most obvious commercial target is lithium recovery. Demand for the metal has climbed as batteries spread across phones, cars, and grid storage, and the industry still leans heavily on extraction processes that can be slow, water-intensive or chemically messy. A membrane that preferentially moves lithium could make both direct extraction and battery recycling cleaner and more efficient.
- Lithium passed through the system about 31 times faster than theory suggested.
- Other ions were blocked more effectively than expected.
- The membrane was built from millions of charged boron nitride nanotubes.
- The team also demonstrated a small device that turned salt concentration differences into electricity.
A tiny power source with a familiar trick
As a proof of concept, the researchers used the same setup to generate electricity from a chemical difference between salt solutions. The output was modest, but enough to run simple devices such as an electronic watch or a calculator. That is not going to replace a grid, but it does show the membrane can do more than sort ions – it can turn separation into power.
The biological analogy is useful here. Electric eels do something broadly similar by controlling ion flow through specialized cells, and nature has spent a very long time optimizing that trick. The open question now is whether these nanotubes can be made durable, cheap and scalable enough to matter outside the lab. If they can, lithium extraction may not be the only industry paying attention.