Although they promise to hold much more energy per charge, they do have shortcomings in their current form, particularly when it comes to safety. Engineers at Northwestern University are now claiming to have overcome these failings by making use of crumpled balls of graphene that fall into line as a scaffold when the battery is charging.

"In current batteries, lithium is usually atomically distributed in another material such as graphite or silicon in the anode," explains Northwestern Engineering's Jiaxing Huang. "But using an additional material 'dilutes' the battery's performance. Lithium is already a metal, so why not use lithium by itself?"

The reason is dendrites, which are microscopic lithium fibers that accumulate on the surface of the anode as the battery charges.