A revolutionary lithium-air battery developed by US experts has four times the energy density of its lithium-ion counterparts, a breakthrough that looks to extend electric car range dramatically.
Innovated by researchers at the Illinois Institute of Technology (IIT) and the U.S. Department of Energy’s (DOE) Argonne National Laboratory, the lithium-air battery will potentially represent a significant milestone for electric cars, which have come under scrutiny due to their limited driving range.
The novel lithium-air battery promises to advance electric car range capabilities, helping to reduce range anxiety among users. The battery may also be employed to power domestic aeroplanes and long-haul trucks in the future.
Larry Curtiss, an Argonne Distinguished Fellow, explained: “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 the 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.”
Electric car range needs to improve to achieve green goals
The amount of electric cars is set to increase drastically over the next decade, as countries such as the US and UK have prohibited the sales of new petrol and diesel cars from 2035.
This legislation is essential and represents a major step toward decarbonising the environment. However, for all their environmentally-harmful qualities, traditional combustion-engine powered vehicles boast on considerable advantage over their electrified successors, which is a larger driving range.
Research from Drive Electric states that today’s average electric car range is between 150-300 miles on a full charge. This means that for longer journeys – journeys that millions worldwide perform daily – current electric car range capabilities are insufficient.
This can cause a knock-on effect that impacts the uptake of electric cars. Poor driving range can lead to range anxiety – where users fear their electric car is not charged enough to reach their destination, leaving them stranded. This can stop some people from purchasing an electric car due to this concern.
The evolution of the lithium-air battery
In previous iterations of the lithium-air battery, the lithium in a lithium metal anode moves through a liquid electrolyte to combine with oxygen during the discharge, producing lithium peroxide (Li2O2) or superoxide (LiO2) at the cathode.
These are then broken down back down into lithium and oxygen components during charging – a chemical sequence that releases energy on demand.
However, the team’s new lithium-air battery boasts a solid electrolyte comprised of a ceramic polymer material that enables chemical reactions that produce lithium oxide (Li2O) on discharge.
Rachid Amine, an Argonne chemist, 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.”
This is the world’s first lithium-air battery to achieve a four-electron reaction at room temperature. Moreover, the battery operates with oxygen from the surrounding environment, removing the need for oxygen tanks to operate, which was a major limitation of the technology.
How did the new battery perform?
The researchers performed a range of tests to prove that a four-electron reaction was occurring, such as using transmission electron microscopy (TEM) o the discharge products on the cathode surface. TEM reveals insights into the four-electron discharge mechanism.
The team also discovered that the new battery does not suffer from the short life cycle of previous lithium-air batteries, with a test cell displaying its performance for 1000 cycles and excellent stability throughout repeated charge and discharge.
Furthermore, due to its solid electrolyte, instead of the liquid electrolytes used in lithium-ion and other battery types, the lithium-air battery does not suffer from the safety issue of the liquid electrolyte catching fire.
Possessing a significant energy density increase compared to lithium-ion batteries, the team’s lithium-air battery may potentially solve electric car range challenges.
Curtiss concluded: “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 kilogramme. That is nearly four times better than lithium-ion batteries.”
