A recent technical breakthrough in battery research has raised the possibility of a next-generation battery with at least twice the power storage capacity of existing lithium-ion cells. It is still some way from commercialization, but the early signs are promising. As reported in the Economist, the new battery is the brainchild of Ju Li of the Massachusetts Institute of Technology. It is a version of what is known as a lithium-air battery, something that has been the holy grail of energy storage research since the 1970s. In theory, such batteries could hold more than four times the energy per kilogram of lithium-ion batteries. But building them has been difficult. The batteries need air to work, specifically oxygen. However, other atmospheric gases such as water vapour and carbon dioxide often damage them. In this article, I explain the advantage of Dr. Li’s design, and what it means for cobalt.