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These New Energy Advances Could Matter

Stanford engineers develop new technologies that provide a clean source of hydrogen fuel, and the world's first rechargeable zinc batteries. Both are potential tools for medical device designers.

Kristopher Sturgis

Stanford Zinc battery innovation
A conventional zinc battery (left) has problems with dendrites growing from the zinc anode and making contact with the metal cathode, causing a short circuit. The redesigned Stanford battery (right) employs plastic and carbon insulators to keep zinc dendrites from reaching the cathode. (Image couresy of Shougo Higashi/Stanford)

Two new studies published this month detail the efforts of a Stanford University research lab looking to address two major energy challenges: clean fuel that can power the transportation industry and renewable grid-scale energy storage.

"Most of the hydrogen supply today is produced through natural gas reforming, which releases significant amounts of carbon dioxide in the process," says Wei Chen, a postdoctoral research fellow in materials science and engineering at Stanford and one of the lead authors on the research. "However, producing clean hydrogen fuel by photovoltaic water splitting is a green process, which is of great benefit to the environment and climate."

Any kind of energy production or storage innovation is potentially good news for the medical device industry, with device designers often finding batteries to be a stumbling block. While microprocessors have exponentially improved under Moore's Law, batteries have not increased in capabilities substantially over the decades.

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Photovoltaic water splitting is a relatively new technology that involves the submersion of solar-powered electrodes in water. Once sunlight hits the electrodes immersed in water, it generates an electric current that can split water into its individual elements--hydrogen and oxygen--all without producing harmful emissions.

Typically solar electrodes are made of silicon, which quickly corrodes when exposed to oxygen, a key byproduct of water splitting. To avoid this, Chen and his colleagues have coated the silicon with iridium and other precious metals.

"The production of clean hydrogen fuel from solar light without producing harmful emissions will be promising," Chen said. "Using an appropriate semiconductor and co-catalysts, water can efficiently and economically split into hydrogen and oxygen under solar light irradiation."

In their second study, Chen and his colleagues teamed up with Shougo Higashi from Toyota Central R&D Labs in Japan to propose a new battery design that could enable solar and wind farms to provide around-the-clock energy for electric grids, even in the absence of wind or sunlight. The new battery design is both inexpensive, and large enough to store surplus clean energy on demand.

The design of the new battery is composed of electrodes made of zinc and nickel, two inexpensive metals that provide the potential for grid-scale storage. Zinc-metal batteries have been used in the past, but they have proven to be less than ideal given their rate of failure and inability to recharge. Chen and his colleagues addressed this challenge by redesigning the battery by separating the zinc and nickel electrodes with a plastic insulator. They also wrapped a carbon insulator around the edges of the zinc electrode, all in an effort to prevent dendrites from forming and short circuiting the battery.

"The zinc rechargeable battery is important for large-scale energy storage applications," Chen says. "This new rechargeable zinc battery addresses the issue of zinc dendrite, which causes the battery to short circuit in conventional zinc batteries."

With this new design, the zinc ions are reduced and deposited on the exposed back surface of the zinc electrode during charging, which means that even if dendrites begin to form, they will form away from the nickel electrode, preventing the battery from short circuiting.

The group demonstrated the stability of their new battery when they were able to successfully charge and discharge the battery more than 800 times without shorting. The group aims to use the design as a template that could be applied to wide variety of other metal batteries as well.

The research on both studies has received support from the U.S. Department of Energy, and Stanford University's Global Climate and Energy Project--a project committed to exploring new solutions to help meet energy needs in a way that protects the environment.

Kristopher Sturgis is a contributor to Qmed.

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