In the quest to improve on the lithium-ion batteries that power today’s mobile devices and electric vehicles, lithium-metal batteries hold a lot of potential. 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.