The lithium sulfur battery has a theoretical capacity of 1675 mAhg−1 and approximately 2300 Wh/kg. The low cost and exceptionally high specific capacity of sulfur renders it an especially attractive battery cathode material for large-scale energy storage, including electric vehicle and grid storage applications. Yet after more than twenty years of research and development at various battery companies and scientific institutions worldwide, key technical problems with the sulfur electrode have precluded meaningful commercialization of the Li-S battery.