Sangil Kim’s lab at the University of Illinois Chicago hums with the quiet intensity of discovery — and lately, with the faint glow of an LED powered entirely by saltwater. In a breakthrough that mimics the electric eel’s natural battery, Kim and his team have created boron nitride nanotube (BNNT) membranes that move lithium ions at speeds once thought impossible. These tiny, tube-shaped channels don’t just filter ions — they accelerate them, opening a new frontier in clean energy and sustainable resource recovery.
The implications are profound. As the world races to decarbonize and electrify, technologies that can efficiently harvest energy from natural gradients — like the mixing of seawater and freshwater — or recover critical minerals from waste streams are no longer luxuries but necessities. Ion transport sits at the heart of these challenges, yet achieving both speed and selectivity has long stumped scientists. Now, Kim’s team has shattered expectations: their BNNT membranes move lithium ions 31 times faster than theoretical predictions, while filtering them from competing ions with remarkable precision.
Published in Nature Nanotechnology, the study reveals that these nanotubes, each just a few nanometers wide, carry a surface charge that creates an “express lane” for lithium ions. When placed between solutions of differing salinity, the membranes generate electric currents simply from ion flow — enough to power small electronics like calculators and watches. In one demonstration, a stack of eight 1 cm² membranes connected in series lit an LED, proving the concept’s potential for scalable energy generation.
"This is a unique mechanism that transports lithium ions very quickly through nanotubes," Kim said, his voice tinged with the quiet excitement of a decade-long pursuit coming to life. The work began when he first arrived at UIC, driven by curiosity about boron nitride’s untapped potential. Now, it could redefine how we think about ion channels in engineered systems. The team, including key contributors Aaditya Pendse, Kun Wang, and other UIC researchers, achieved this through precise alignment of functionalized BNNTs under a 40-Gauss magnetic field — a technique that ensures uniform orientation and optimal performance.
Beyond energy, the membranes offer a sustainable path to lithium recovery, a growing concern as millions of batteries reach end-of-life. Current recycling methods are energy-intensive and inefficient, but these nanotubes could selectively extract lithium from complex mixtures, turning waste into resource. The team plans to explore this application further, while also unraveling the physics behind the anomalous transport.
As climate pressures mount, nature continues to inspire solutions — from electric eels to engineered membranes. In a Chicago lab, saltwater now powers light and hope, one ion at a time.