Reducing the size and weight of batteries with the necessary charge capacity has been a long-running challenge for developers of electric cars. A new type of air-fuelled battery developed in Scotland could solve the problem. It provides up to 10 times the energy storage of designs currently available.

“This dramatic increase in capacity could pave the way for a new generation of electric cars, mobile phones and laptops,” claims Peter Bruce, a chemistry professor at the University of St. Andrews who’s heading up the four-year research project along with colleagues at several other universities.

Improved capacity in the St. Andrews Air (STAIR) cell is created by the addition of a component that uses oxygen drawn from the air during discharge, replacing one chemical constituent used in rechargeable batteries today. Not having to carry the chemicals around in the battery offers more energy for the same size battery.

In addition, Bruce claims that the STAIR cell would be cheaper than today’s rechargeable batteries. “The new component is made of porous carbon, which is far less expensive than the lithium cobalt oxide it replaces,” he explains. Because the carbon component’s interaction with air can be repeated, it creates a cycle of charge and discharge.

“The new design has the potential to improve the performance of portable electronic products and give a major boost to the renewable energy industry,” Bruce points out. “The batteries will enable a constant electrical output from sources such as wind or solar, which stop generating when the weather changes or night falls.

“Our target is to get a five- to 10-fold increase in storage capacity, which is beyond the horizon of current lithium batteries,” adds Bruce. “Our results so far are very encouraging and have far exceeded our expectations.”

According to Bruce, the key is to use oxygen in the air as a reagent, rather than carry the necessary chemicals around inside the battery. The oxygen, which is drawn in through a surface of the battery exposed to air, reacts within the pores of the carbon to discharge the battery. “Not only is this part of the process free, the carbon component is much cheaper than current technology,” claims Bruce. He estimates that it will be at least five years before the STAIR cell is commercially available.

Bruce and his colleagues are currently focusing on understanding more about how the chemical reaction of the battery works and investigating how to improve it. The engineers are also developing a prototype battery for small applications, such as mobile phones or MP3 players.