Scientists at the University of Chicago and New York University have made an important discovery about how water helps transport charged particles in energy technologies like fuel cells and batteries.

Their research, published in Nature Communications, challenges the idea that more water always improves performance in ion-conducting membranes.

These special membranes, called anion exchange membranes (AEMs), help guide negatively charged ions (anions) through electrochemical devices, such as fuel cells, to generate electricity or store energy.

For a long time, researchers believed that these membranes needed large amounts of water to help ions move faster.

However, too much free-flowing water can weaken the structure of the membranes over time.

The new study shows that the key to efficient ion movement isn’t just having more water—it’s about how the water is structured inside the membrane.

How water helps ions move

AEMs are made of thin materials containing molecules with a positive charge. These molecules attract anions and help push them through the membrane while blocking positively charged ions (cations).

This movement of ions is crucial for making electrochemical devices work efficiently.

Scientists already knew that water plays a role in this process. However, adding too much free water makes the membranes fragile and limits their use in dry environments. The research team wanted to understand exactly how water behaves inside AEMs and how it affects ion transport.

The key discovery: structured water networks matter

To study this, researchers combined laboratory experiments with computer simulations to track water molecules at an extremely small and fast scale—down to trillionths of a second.

They used a technique called two-dimensional infrared spectroscopy (2D IR) to capture how water molecules move and interact.

They found that instead of needing extra water, AEMs work best when they have just enough water to form well-connected hydrogen bond networks.

These networks allow ions to move smoothly, even without high amounts of free water.

If there’s too little water, the hydrogen network is incomplete, and ions struggle to move. But if there’s too much free water, the membrane becomes weak and less effective.

“We observed that even with lower water levels, ion movement improves as long as the water molecules form a well-structured network,” said Ge Sun, a graduate student at the University of Chicago and co-lead author of the study.

A smarter approach to clean energy technology

This discovery changes how engineers should design AEMs for fuel cells and other clean energy technologies. Instead of adding extra water, they can focus on creating membranes with better-structured water networks. This could make fuel cells, batteries, and other energy storage devices more efficient and durable, especially in dry environments.

“By understanding how water molecules organize inside these membranes, we can design next-generation materials that work better and last longer,” said co-author Prof. Shrayesh Patel from the University of Chicago.

Beyond energy storage, this research also provides new tools to study molecular behavior in other scientific fields. The combination of experimental data and simulations used in this study could help solve many challenges involving the movement of molecules in different materials.

Source: University of Chicago.