Electric Tesla Roadster - Obtained with thanks from e-connected on Flickr: http://www.flickr.com/photos/e-connected/. Click image for the wallpaper sized 2298 x 1535 pixel version.
IBM discovered a new electrode for lithium-air batteries, and it facilitates driving electric vehicles 500 miles after each charge.
Lithium-air battery technology is recent, but not new. It does have the potential to store a significant amount of energy in a very lightweight package. This is otherwise known as a high gravimetric energy density. Gravimetric energy density is measured in Wh/kg of batteries, or watt-hours per kilogram.
Lithium-air batteries use carbon as their positive electrode (unlike typical li-ion batteries that use oxides of metals such as lithium cobalt oxide), and that carbon reacts with oxygen in the air to generate electricity. Batteries do not store electricity, they generate it.
IBM decided to start work on these batteries due to their potential and discovered that the oxygen in the air is reacting with both the carbon electrode mentioned, ans also with the battery’s electrolyte. This ruins the electrolyte.
So, physicist Winfried Wilcke and his colleague Alessandro Curioni at IBM’s Zurich research labs in Switzerland used the Blue Gene supercomputer to simulate extremely detailed models of the reactions using alternative electrolytes until they finally found a more suitable one, which is confidential.
Winfried Wilcke said: “We now have one which looks very promising,”, but there are several research prototypes t hat have been demonstrated.
Batteries with a higher energy density enable hybrid-electric and electric vehicles to drive further per charge because they are lighter. Lighter batteries weigh down the vehicle less, therefore, the vehicle will be lighter overall and require less energy per mile it travels, conserving the energy in the batteries. This translates to more energy available for driving. Another way to look at it is: Each kWh (kilowatt-hour) of energy takes you further.
A greater energy density also means that fewer batteries can be used to achieve the same range that you would using ordinary batteries, which is usually less than 100 miles in ordinary cars such as the Nissan Leaf and Chevy Volt. The Tesla Roadster uses many batteries which enable it to achieve a 244 mile range per charge.
Apart from that, fewer batteries cost less money. So you can either increase the vehicle’s range, or cut the cost by using fewer batteries. I should also add that lighter vehicles are faster and handle better.
So, as you probably realized now: A significantly improved energy density really can have a far reaching impact on vehicles.
Typical lithium-ion batteries such as the lithium cobalt and lithium-iron phosphate types have a much a lower energy density, and as a result of this, electric vehicles powered by them often have a driving range of less than (but not limited to) 100 (160 km) miles per charge. They are, however, more practical than older lithium-air batteries that are unreliable due to chemical instability.
The hope is to have a full-scale battery prototype operational by 2013 and commercial batteries around 2020.
Source: New Scientist
