3D sponge mitigates against fire-prone batteries

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Researchers in the US claim to have developed a safer alternative to fire-prone lithium-ion batteries, which were recently banned for some applications on US Navy ships.

Debra R. Rolison (2nd from left), Jeffrey W. Long (center), and Joseph F. Parker (4th from left)
Debra R. Rolison (2nd from left), Jeffrey W. Long (center), and Joseph F. Parker (4th from left)

Joseph Parker, Jeffrey Long, and Debra Rolison from the US Naval Research Laboratory's (NRL) Advanced Electrochemical Materials group are leading the effort to create an entire family of safer, water-based, zinc batteries.

They are said to have demonstrated a breakthrough for nickel-zinc (Ni-Zn) batteries in which a 3D zinc "sponge" replaces the powdered zinc anode traditionally used.

With 3D zinc, the battery provides an energy content and rechargeability that are claimed to rival lithium-ion batteries while avoiding safety issues associated with lithium.

Their research appears in Science. Additional contributors include former NRL staff scientist, Christopher Chervin, National Research Council postdoctoral associate, Irina Pala, as well as industry partners Meinrad Machler and CEO of EnZinc, Inc., Michael Burz.

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

Zinc-based batteries are the go-to global battery for single-use applications, but are not considered rechargeable in practice due to their tendency to grow dendrites inside the battery, which can cause short circuits.

"The key to realising rechargeable zinc-based batteries lies in controlling the behaviour of the zinc during cycling," said Parker, lead author on the paper. "Electric currents are more uniformly distributed within the sponge, making it physically difficult to form dendrites."

The NRL team demonstrated Ni-3-D Zn performance in three ways: extending lifetime in single-use cells; cycling cells more than 100 times at an energy content competitive with lithium-ion batteries; and cycling cells more than 50,000 times in short duty cycles with intermittent power bursts, similar to how batteries are used in some hybrid vehicles.

With the benefits of rechargeability, the 3D zinc sponge is ready to be deployed within the entire family of Zn-based alkaline batteries across the civilian and military sectors.

"We can now offer an energy-relevant alternative, from drop-in replacements for lithium-ion to new opportunities in portable and wearable power, and manned and unmanned electric vehicles, while reducing safety hazards, easing transportation restrictions, and using earth-abundant materials," said Long.

On April 14, 2017 the US Navy issued a statement saying that it was banning e-cigarettes aboard ships, submarines, aircraft, boats, craft and heavy equipment. The policy was introduced in response to continued reports of explosions of so-called Electronic Nicotine Delivery Systems (ENDS) due to overheating lithium-ion batteries.