New Lithium-Air Batteries Could Energize Electric Cars
…but it's still a ways off yet, so don't expect to see it at your local dealer this year.
In a major milestone in the history of battery development, UK researchers are closer to developing a lithium-air battery, which could deliver up to five times the energy per unit mass that the existing lithium-ion technology allows.
What does that mean in real terms? Well, how about talking all week on your mobile phone without a recharge? Or driving 800 kilometres in your electric car?
The research was led by Professor Peter G Bruce of the University of St. Andrews in Scotland, and published in Science Express. The work describes a chemical reaction that allows the battery to be recharged without electrode degradation.
Of the discovery, Professor Bruce says “we have demonstrated that sustainable cycling is possible. That is the real step here. We haven’t solved all the practical problems and it’s not a solution, but it does demonstrate this critical reaction can be sustained and cycled.”
The push for a lithium-air battery is motivated by the fact that air is used as the cathode and lithium metal as the anode. Oxygen is cheap and light. This leads to batteries being conceived that don’t require the heavy casing to contain the electrodes we see today.
In a normal lithium-ion battery, lithium ions are transferred from the cathode to the anode through an electrolyte. When the battery is used, the process is reversed and the ion flow produces an electric current.
In the lithium-air model, oxygen enters the cathode and combines with lithium ions to generate lithium peroxide, which accumulates as the battery is discharged. In testing the researchers were able to produce this reaction repeatedly without decomposition using a thin film of gold as an electrode.
“Hopefully it’s not only gold that does it,” says Steve Visco, president and CEO of Polypus, a California based company that is working on not only lithium-air, but also lithium-sulfur and lithium-seawater batteries. As gold is expensive, he says it “would not be practical unless you are sending it into space where cost doesn’t matter.”
“It certainly wouldn’t work for electric vehicles.”
The hope shared by Visco and Bruce is that they are on the way. Bruce says his experiment is but one of many that must be a success before this battery can actually be built.
“It’s still a long way off. What we’ve done demonstrates the importance of basic scientific studies in this area. If you rush out and try to make a battery with the knowledge that currently existed you would be unlikely to succeed.”