Safer alternative to li-ion batteries developed

Researchers at the US Naval Research Laboratory (NRL) have developed a safer alternative to fire-prone lithium-ion batteries, which were recently banned for some applications on US Navy ships and other military platforms.

The effort is developing a family of water-based zinc batteries. Researchers have demonstrated a key technology breakthrough for nickel–zinc (Ni–Zn) batteries in which a three-dimensional (3-D) Zn 'sponge' replaces the powdered zinc anode traditionally used. The resulting battery provides an energy content and rechargeability that rival lithium-ion batteries while avoiding the safety issues that continue to plague lithium.

Zinc-based batteries are not considered rechargeable due to their tendency to grow conductive whiskers (dendrites) inside the battery, which can cause short circuits. The team is working to overcome this by controlling the behavior of the zinc during cycling so that 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 over 100 times at energy content competitive with lithium-ion batteries and cycling cells over 50,000 times in short duty-cycles with intermittent power bursts, similar to the way batteries are used in some hybrid vehicles.

Jeffrey Long from NRL's Advanced Electrochemical Materials group said: '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 while reducing safety hazards, easing transportation restrictions, and using earth-abundant materials.'