New design for lithium-air battery could offer much longer driving range compared with the lithium-ion battery

Many owners of electric cars have wished for a battery pack that could power
their vehicle for more than a thousand miles on a single charge. Researchers
at the Illinois Institute of Technology (IIT) and U.S. Department of
Energy’s Argonne National Laboratory have developed a lithium-air battery
that could make that dream a reality. The team’s new battery design could
also one day power domestic airplanes and long-haul trucks.

The main new component in this lithium-air battery is a solid electrolyte
instead of the usual liquid variety. Batteries with solid electrolytes are
not subject to the safety issue with the liquid electrolytes used in
lithium-ion and other battery types, which can overheat and catch fire.

More importantly, the team’s lithium-air solid electrolyte design can
potentially boost the battery’s energy density by as much as four times
above lithium-ion batteries, which translates into longer driving range.

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.

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 reaction stores and releases
energy on demand.

The chemical reaction yielding lithium oxide involves four electrons stored
per oxygen molecule, whereas that for lithium superoxide or peroxide only
involves one or two electrons. More electrons stored translates into higher
energy density.

The team’s lithium-air design is the first lithium-air test cell 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.

With further development, the team expects their new battery design could
reach a record energy density of 1,200 watt-hours per kilogram, nearly four
times better than lithium-ion batteries.