The technology has been licensed to EnZinc, a startup in San Anselmo, California, that is developing batteries for hybrid cars, electric bikes, and wearable electronics.
The team at NRL’s Advanced Electrochemical Materials group have demonstrated a breakthrough for nickel-zinc (Ni-Zn) batteries in which a three-dimensional Zn “sponge” replaces the powdered zinc anode traditionally used. With 3D Zn, the battery provides an energy content and rechargeability similar to lithium-ion batteries without the risk of short-circuits and fires.
“Our team at the NRL pioneered the architectural approach to the redesign of electrodes for next-generation energy storage,” said Debra 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 well established as primary batteries, but are not considered rechargeable in practice due to their tendency to grow conductive whiskers (dendrites) inside the battery, which can grow long enough to cause short circuits.
“The key to realizing rechargeable zinc-based batteries lies in controlling the behaviour of the zinc during cycling,” said Joseph Parker, lead author on the paper. “Electric currents are more uniformly distributed within the sponge, making it physically difficult to form dendrites.”
The Ni-3D Zn technology is used to extend lifetime in single-use cells; cycle cells more than 100 times at an energy content competitive with lithium-ion batteries; and cycle 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 3-D Zn 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,” said Jeffrey Long, “while reducing safety hazards, easing transportation restrictions, and using earth-abundant materials.”