Researchers in the US have developed a new and safer lithium-air battery, tested for a thousand cycles in a test cell, which can store far more energy than today’s common lithium-ion batteries.
The research team, from the Illinois Institute of Technology (IIT) and US Department of Energy’s Argonne National Laboratory, believes the new battery design could also one day power domestic airplanes and long-haul trucks.
The main component in the lithium-air battery is a solid electrolyte instead of the usual liquid variety.
Batteries with solid electrolytes are not subject to the safety issues of liquid electrolytes used in lithium-ion and other battery types, which can overheat and catch fire.
More importantly, the team’s battery chemistry with the solid electrolyte can potentially boost the energy density by as much as four times above lithium-ion batteries, which translates into longer driving range.
Argonne Distinguished Fellow Larry Curtiss said: “For over a decade, scientists at Argonne and elsewhere have been working overtime to develop a lithium battery that makes use of the oxygen in air.
“The lithium-air battery has the highest projected energy density of any battery technology being considered for the next generation of batteries beyond lithium ion.”
In past lithium-air designs, the lithium in a lithium metal anode moves through a liquid electrolyte to combine with oxygen during the discharge, yielding lithium peroxide or superoxide at the cathode.
The lithium peroxide or superoxide is then broken back down into its lithium and oxygen components during the charge – this chemical sequence stores and releases energy on demand.
The team’s new solid electrolyte is composed of a ceramic polymer material made from relatively inexpensive elements in nanoparticle form.
This new solid enables chemical reactions that produce lithium oxide on discharge.
Argonne Chemist Rachid Amine said: “The chemical reaction for lithium superoxide or peroxide only involves one or two electrons stored per oxygen molecule, whereas that for lithium oxide involves four electrons.”
More electrons stored means higher energy density.
The team’s lithium-air design is the first lithium-air battery that has achieved a four-electron reaction at room temperature.
It also operates with oxygen supplied by air from the surrounding environment.
The capability to run with air avoids the need for oxygen tanks to operate, a problem with earlier designs.
Past lithium-air test cells suffered from very short cycle lives.
The team established that this shortcoming is not the case for their new battery design by building and operating a test cell for 1000 cycles, demonstrating its stability over repeated charge and discharge.
Curtiss said: “With further development, we expect our new design for the lithium-air battery to also reach a record energy density of 1200 watt-hours per kilogram.
“That is nearly four times better than lithium-ion batteries.”
