Lithium-ion batteries are a fairly recent technology, but researchers are already working to replace them. One potential replacement is a lithium-air battery design that could change the way we power our world and make electric cars a truly viable method of transportation.
Lithium-air batteries are known for offering an energy density that rivals gasoline and an ability to be recharged multiple times without losing effectiveness.They have been tested by various teams in the past, but often have critical issues that make commercial use impractical. These issues range from low efficiency to an inability to operate using anything other than purified oxygen.
The team's paper discusses the benefits of a graphene electrode (black) and the production of lithium hydroxide particles (pink) as a lithium-air battery discharges. (Image courtesy of University of Cambridge/T. Liu et al.)
Recently, a team of engineers at the UK’s University of Cambridge decided to rethink the lithium-air battery and may have found an answer to the technology’s problems.
The team adjusted the general design for lithium-air batteries by using a highly porous, spongy carbon electrode made from graphene. The new design also incorporates the use of lithium iodide as a stabilizing additive.
Improving Lithium-Air Batteries
A working laboratory demonstration of this new design shows that the combination of a graphene electrode and lithium iodide could be game changing for lithium-air technology.
The use of lithium iodide as a stabilizer helps to reduce the unwanted chemical reactions which typically cause cells in the battery to die. This means the battery remains stable after multiple charge and discharge cycles and it also improves battery longevity.
When combined with the graphene electrode, the demonstration battery showed promising results in its efficiency. The voltage gap, the difference between charge and discharge, was 0.2 volts – approximately the same efficiency as a lithium-ion battery.
Previous lithium-air batteries generally only managed a voltage gap of 0.5-1.0 volts.
Assessing the Potential
Although the team at the University of Cambridge warns that it will likely be ten years or more before this technology is commercially available, it has huge potential – especially for electric cars.
As lithium-air battery technology improves, it could begin to take electric cars across countries rather than cities on a single charge.
It would also enable an electric car to travel approximately 400 miles on a single charge.
Currently, electric cars generally have a maximum range of around 100 miles.
Lithium-air battery technology still faces several issues. The team’s goal is to get the battery to function properly in regular air, but at this point it still requires pure oxygen as carbon dioxide and nitrogen can be harmful to the graphene electrode.
“What we’ve achieved is a significant advance for this technology and suggests whole new areas for research – we haven’t solved all the problems inherent to this chemistry, but our results do show routes forward towards a practical device,” said Clare Grey, professor at the University of Cambridge’s department of chemistry.
For more information, read the team’s paper on the lithium-air battery.