August 31, 2017
During routine materials experimentation at the U.S. Army Research Laboratory, a team of researchers observed a bubbling reaction when adding water to a nano-galvanic aluminum-based powder. The team further investigated and found that water splits apart when coming into contact with their unique aluminum nanomaterial. The reaction surprised the researchers, but they soon considered its potential implications for future power and energy applications.
"The hydrogen that is given off can be used as a fuel in a fuel cell," said Scott Grendahl, a materials engineer and team leader. "What we discovered is a mechanism for a rapid and spontaneous hydrolysis of water."
Scientists have known for a long time that hydrogen can be produced by adding a catalyst to aluminum. But these methods take time, elevated temperature, added electricity, and/or toxic chemicals such as sodium hydroxide, potassium hydroxide, or acid.
"In our case, it does not need a catalyst," said Dr. Anit Giri, a physicist with the lab's Weapons and Materials Research Directorate. "Also, it is very fast. For example, we have calculated that one kilogram of aluminum powder can produce 220 kilowatts of energy in just three minutes." That metric doubles if you consider the amount of heat energy produced by the exothermic reaction, he said.
"That's a lot of power to run any electrical equipment," Giri said. "These rates are the fastest known without using catalysts such as an acid, base or elevated temperatures." Grendahl said the discovery is dramatic in terms of what can be achieved.
"There are other researchers who have been searching their whole lives and their optimized product takes many hours to achieve, say 50 percent efficiency," Grendahl said. "Ours does it to nearly 100 percent efficiency in less than three minutes."
Additionally, since the nanomaterial powder has the potential to be 3D printed, researchers envision future uses of the material being used by soldiers to charge mobile devices in the field, or powering air and ground robots that can self-destruct after mission complete. Giri said the Army Research Laboratory focuses on giving soldiers advantages, and that currently recon teams can be limited by the number of days their batteries last in various types of equipment.
The next steps are to document the discovery with scholarly papers and intellectual property protections, some of which are ongoing, and to coordinate further applications with scientists and engineers across the laboratory.