Reuters reports on a tantalizing advance in battery technology described this week by Cambridge researchers, who have made large enough steps toward a practical lithium-oxygen battery to give a laboratory demo of their system. Commercially available lithium-oxygen batteries would be significant because they would have the potential to deliver the desired power thanks to a high energy density - a measure of energy stored for a given weight - that could be 10 times that of lithium-ion batteries and approach that of gasoline. They also could be a fifth the cost and a fifth the weight of lithium-ion batteries. But problems have beset lithium-oxygen batteries that affect their capacity and lifetime, including troublesome efficiency, performance, chemical reaction and potential safety issues and the limitation of needing pure oxygen rather than plain old air. The Cambridge demonstrator battery employs different chemistry than previous work on lithium-air batteries, for example using lithium hydroxide rather than lithium peroxide. It also uses an electrode made of graphene, a form of carbon. The result was a more stable and efficient battery." Some more about this research can be gleaned from Clare Grey's web page at Cambridge.