News | Jun 20, 2017

Get ready for rechargeable batteries made of zinc. (Yes, zinc)

With plans for electric car and microgrid applications, EnZinc says new batteries offer powerful alternative to fire-prone lithium batteries

News Article Image of Get ready for rechargeable batteries made of zinc. (Yes, zinc)

The Navy has banned the use of some lithium-ion battery uses, including electronic cigarettes, on ships, submarines, and aircraft because of fire concerns. (U.S. Navy photo by Paul Archer)

Thomas Edison patented a zinc battery in 1900, but it had problems the prolific American inventor couldn’t understand without an electron microscope.

Today, scientists at the Naval Research Laboratory (NRL) aren’t so limited and have sorted out zinc’s problems.

On June 16, NRL’s patented zinc electrode battery technology was licensed to EnZinc, a startup in San Anselmo. The engineering firm is focused on bringing the new batteries to microgrids and electric vehicles, including e-bikes, which is exactly what Edison had hoped to build 117 years ago.

“There’s significant interest in our plans to commercialize this technology for two such important areas of the renewable marketplace,” said Michael Burz, CEO of EnZinc.

Since Edison’s patent, zinc has been used in disposable batteries, but never competed in the fast-growing rechargeable battery market because they don’t evenly distribute current under load thereby growing micro-whiskers called dendrites that eventually short-circuit the battery.

But zinc doesn’t catch fire like lithium-ion batteries have, so the NRL’s Advanced Electrochemical Materials team created zinc electrodes using powdered zinc, emulsified in oil and water, then baked in a mold, resulting in a monolithic 3-D zinc sponge-like structure containing microscopic cavities.

“Our team at the NRL pioneered the architectural approach to the redesign of electrodes for next-generation energy storage,” said Dr. Debra Rolison, senior scientist and principal investigator on the Navy project. “The 3-D sponge form factor allows us to reimagine zinc, a well-known battery material, for the 21st century.”

Dr. Joseph Parker, a materials scientist at the Naval Research Laboratory, shows a 3-D zinc battery anode.

Dr. Joseph Parker, a materials scientist at the Naval Research Laboratory, shows a 3-D zinc battery anode.

The sponge architecture guarantees smooth electron flow, increasing discharge capacity by 50 percent and preventing dendrite growth and micro-cracking experienced by other batteries that naturally fluctuate in size. The Navy’s new battery was fully-recharged tens of thousands of times in 2013 tests.

“The key to realizing rechargeable zinc-based batteries lies in controlling the behavior of the zinc during cycling,” said NRL’s Joseph Parker. “Electric currents are more uniformly distributed within the sponge, making it physically difficult to form dendrites.”

With the license, EnZinc’s engineering team can begin designing batteries for mass manufacturing. Burz said the batteries can also be tailored for military applications by adjusting the size of the zinc particles and the baking temperature.

“It’s simple and elegant… They’ll replace lead-acid batteries and displace lithium-ion batteries,” he said. And zinc is cheaper than lithium and other exotic metals (such as cobalt) used in lithium-ion batteries. It’s the fourth most mined metal on the planet. Plus, zinc batteries don’t need flammable electrolytes to operate, or heavy shielding to prevent punctures and fire. And as an added bonus: they are totally recyclable.

EnZinc’s partnership with the lab began in 2012, but in 2016 the licensing “required some complex negotiations,” said Burz, crediting TechLink’s Austin Leach for smoothing out the process.

“Dr. Leach’s patience, knowledge of tech-transfer process, the NRL environment and its licensing processes, his good humor, and diplomatic skill were well used, much appreciated, and critical to the success of the negotiations,” Burz said.

Troy Carter can be reached at troy.carter@montana.edu or 406-994-7798.

Headshot Image of Austin Leach, PhD, CLP

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