Boron-based process creates hydrogen at room temp

Article By : University at Buffalo

The method, which cuts the weight of the hydrogen source, could find application in drones, back-up generators for remote cell towers and H₂-based cars.

In his efforts to prevent lithium-ion batteries from wearing out, a PhD candidate at the University at Buffalo has developed a system to create nanosized particles of pure boron that can generate hydrogen when mixed with water at room temperature.

The applications could be vast—from dramatically extending the range of drones, to powering back-up generators for remote cell towers, to tiny hydrogen generating machines for cars that run on it. And it is why Parham Rohani launched NanoHydroChem LLC, which he hopes will become a holding company for the concepts he is focused on in the laboratory.

Rohani's method reduces the weight of a hydrogen source. Current hydrogen storage methods involve heavy tanks to contain the gas. By avoiding the heavy tanks, the energy density of the hydrogen source—its watt-hour/weight—can be greatly increased.

“The energy density of hydrogen available from our system is two to three times that of lithium-ion batteries,” he said. That energy boost could make hydrogen a much more attractive energy source.

But there are challenges.

Expensive process

Rohani’s method begins with diborane gas (B2H6), which is very costly. The gas is blasted with a laser, which breaks the covalent bond between the two boron atoms. The gas is then quickly cooled to generate nanoparticles of pure boron (about 20nm wide). The nanoparticles are then mixed with sodium hydride, pelletised and placed in a cartridge that can be discharged to mix with water, which releases hydrogen. That hydrogen can directly power a fuel cell to generate electricity.

The reaction takes place at room temperature, making it the first time pure boron has been captured under those conditions.

“This creation of small nanoparticles of boron is our invention,” Rohani said. “The nanosize has more surface area, and this allows the hydrolysis reaction to occur at room temperature.”

The byproduct of the hydrolysis is a form of boron oxide, which can be regenerated to make boron again. “It is complicated, but it can be done,” Rohani said.

The cost of the diborane makes the process cost prohibitive for most uses, so Rohani is working on that challenge. “What I’m trying to do is change the whole process to make it cheaper.”

Rohani’s PhD thesis involves his other business concept—extending the life of lithium-ion batteries with high-capacity silicon anodes. As the batteries are charged and then drained, the anode material expands and contracts, causing tiny cracks to form on the surface. Electrolytes fill in the cracks, and over time this degrades the battery.

Rohani is working on a way to keep the electrolytes away from the silicon.

“If you buy a lithium-ion battery, its capacity decreases over time. We need to find a cost effective process to extend the battery life,” he said. “I want to solve this problem and to make it as cheap as possible.”

Rohani’s PhD advisor is Mark T. Swihart, a UB Distinguished Professor in the Department of Chemical and Biological Engineering and executive director of UB’s New York State Center of Excellence in Materials Informatics. Swihart said there may be applications where the extra cost of the hydrogen-making process is worthwhile, like powering drones that inspect power lines or pipelines.

“If the drone can go twice as far, it might work,” he said.

Additionally, the diborane used in the process is extremely pure, because it is made for the microelectronics industry. If a market could be established for less pure diborane, the price could drop, Swihart said.

Still, much engineering needs to be done on the system. Swihart said the water used to make hydrogen could be recycled to further reduce the weight.

Rohani’s other work on lithium-ion batteries involves encapsulating the silicon particles to keep the electrolyte interface that forms off the silicon while still allowing lithium ions out to generate electricity.

“People have tried all kinds of structures, but nothing has taken off yet,” Swihart said.

Success in that area could become extremely valuable given all the lithium-ion batteries used in cellphones and other electronics.

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