Innovative Liquid Promises Easier Hydrogen Transport and Storage
- Ritambhara K
- Jul 27
- 3 min read
Hydrogen holds great promise as a clean fuel for the future,but bringing it from the lab into everyday use is a complex challenge. Most materials that contain high amounts of hydrogen are solid at room temperature, or they only exist as liquids under extreme conditions—like high pressure or very low temperatures.
Take ammonia borane, for example: it’s a solid compound rich in hydrogen, but it only releases that hydrogen when heated and often generates unwanted byproducts in the process.
Creating a hydrogen-rich liquid that remains stable under normal conditions could greatly simplify how hydrogen is stored and transported. Researchers have been working on this by tweaking the chemical structure of existing storage materials or by adding compounds that help release hydrogen more efficiently.
One promising breakthrough in hydrogen storage comes from deep eutectic solvents (DESs)—mixtures that melt at much lower temperatures than their individual components. This characteristic makes them especially useful for hydrogen storage, as they can turn solid hydrogen-rich materials into manageable liquids under milder conditions. However, until recently, DESs hadn’t been made using hydrides—compounds that are particularly rich in hydrogen and could offer a more efficient way to store hydrogen in liquid form.
Now, researchers from the labs of Professors Andreas Züttel at EPFL and Satoshi Horike at Kyoto University have created the first hydride-based DES: a clear, stable, hydrogen-rich liquid that remains in liquid form at room temperature. Impressively, this new DES can hold up to 6.9% hydrogen by weight—surpassing several key hydrogen storage benchmarks, including those set by the U.S. Department of Energy for 2025.
To develop the liquid, the team experimented by physically mixing ammonia borane and tetrabutylammonium borohydride in various ratios. They discovered that a mixture containing between 50% and 80% ammonia borane resulted in a stable, amorphous liquid—meaning it doesn’t recrystallize, even when cooled.
Using spectroscopy, the researchers found that the molecules in the mixture formed strong hydrogen bonds, disrupting their usual solid structure and allowing the liquid to remain stable even at temperatures as low as -50°C. When heated to just 60°C, the liquid begins to release hydrogen—much earlier than most hydrogen-rich solids—making hydrogen access more energy-efficient and practical for real-world use.
By combining ammonia borane with tetrabutylammonium borohydride, the team created a new hydrogen-rich liquid that resists crystallization under normal conditions. The mixture has a glass transition temperature of -50°C, meaning it stays fluid well below freezing.
The liquid remains stable for weeks when stored in a dry environment and boasts one of the lowest densities reported for hydrogen-rich liquids. When heated, it efficiently releases clean hydrogen gas with minimal impurities. Notably, only the ammonia borane component breaks down first, suggesting that parts of the mixture could potentially be recovered and reused, adding to its practicality and sustainability.
This new deep eutectic solvent (DES) has the potential to significantly simplify and improve the safety of hydrogen storage and transportation. Rather than depending on high-pressure tanks or extremely cold liquids, industries could turn to stable, easy-to-handle hydrogen carriers that remain liquid at room temperature.
Beyond hydrogen storage, this breakthrough could pave the way for designing customized liquids for a range of applications, from chemical manufacturing to sustainable energy solutions. The discovery not only advances hydrogen research but also opens exciting possibilities for real-world energy technologies.
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