The 3-D printed electrodes release the gas

Alkaline water electrolysis has been touted as a path to establishing a hydrogen economy by converting intermittent renewable energies into clean, hydrogen-based chemical energy.

However, current technology has only achieved low current densities and voltage efficiencies.

To make electrolysis more enterprising, a team from Lawrence Livermore National Laboratory (LLNL) has collaborated with the University of California, Santa Cruz and two other institutions to develop a 3-D printed electrode that reduces the problems that occur with the gas bubbles that are generated in the process.

A key to making electrolysis achieve a higher current density depends on the gas bubbles created in the process. The bubbles often mix, jam and become trapped, making it difficult for them to escape.

“This new electrode eliminates gas bubbles faster. You don’t want the bubbles to get trapped in the material; you want to be able to extract them as quickly as possible and use them as a fuel source,” said LLNL materials scientist Cheng Zhu, the lead author of an LLNL article that appeared in Advanced energy materials.

The new electrode’s unique 3-D printed architecture suppressed coalescence, jamming and trapping of gas bubbles and resulted in rapid bubble release. The team found that the current density was 50 times better than the laboratory standard.

The team also used simulations to understand how gas is formed, how it escapes, and how fast it escapes. Since it is not possible to see this process inside an electrode, simulations were instrumental in the design.

“The modeling helped us understand the fundamental science of the phenomena we saw happening,” said Rongpei Shi, the LLNL materials scientist who conducted the simulations. “The electrodes aren’t transparent, so you can’t look in there and see what’s going on. The controlled platform and modeling are unprecedented enough to uncover the physics going on inside the electrode.”

The work demonstrates a novel approach to the design of 3-D electrodes to enable rapid transport and release of bubbles to improve the total catalytic activity of the electrode at commercially relevant current densities.

“A lot of work has been done on the end of the electrolysis material, looking for catalyst materials for electrodes. What this team has shown is that the actual architecture of the components is just as important, especially at high production speeds,” he said. stated Brandon Wood, LLNL Associate Program Leader for Hydrogen and Computational Energetic Materials in the Materials Science Division and co-author of the article.