Scientists from the University of Saint Andrews in Scotland recently made a breakthrough in the production of EV lithium-ion batteries by adding gold to the mix. The team previously discovered that an air-breathing lithium-ion battery could potentially store up to 10x times the energy that standard lithium-ion batteries do, but they hadn’t figured out what materials would make the right combination. They now believe that gold could be the key, as it can stand up to the rigors of repeated charging and discharging.
The Saint Andrews researchers used gold to create an experimental battery that will pave the way to a viable mass-market lithium battery that could potentially power an electric car for hundreds of kilometers.
In their paper, which was published in the journal Science, the team said that their experimental lithium–air battery featured an organic electrolyte (dimethyl sulfoxide) and a porous gold electrode which managed to maintain 95% capacity after “100 charge–discharge–recharge cycles.”
The problem with current lithium ion batteries is their storage capacity, which has led to the slow uptake of electric vehicles. These batteries use a metal oxide or metal phosphate cathode as a positive electrode, a carbon-based anode as a negative electrode, and an electrolyte to conduct lithium ions from one electrode to the other. However lithium-air batteries would change all that for the better, whilst increasing efficiency.
“Lithium ion batteries are in many ways the best we have right now in terms of energy density, and they’ll be with us for quite some time, including in electric vehicles,” according to Saint Andrews chemistry professor Peter Bruce. “But we already know that if we can double the energy storage in those batteries, that’s going to be the limit of what’s possible. Lithium ion batteries won’t meet our needs moving forward, hence the interest in looking at alternatives such as lithium–air.”
Lithium–air batteries essentially take oxygen from the air whilst the vehicle is in motion. This reduces the need for heavy-metal oxides that add weight to the battery while allowing the oxygen molecules to react with lithium ions and electrons on the surface of a porous gold cathode to form lithium peroxide. This process would then power the car’s motor.
“We’ve demonstrated that the electrochemical reaction that needs to take place in an air battery does work and does seem to be reversible,” Bruce said, however he stresses that it was gold that made it all possible. “We don’t really know what it is about the nanoporous gold that seems to give us this level of stability, more work needs to be done to determine this.”
Images: Argonne National Laboratory