Scientists at the DoE's Oak Ridge National Laboratory (ORNL) have struck the battery mother lode: They've created an all-solid lithium-sulfur battery that is cheaper, less flammable, and has four times the energy density of conventional lithium-ion batteries. Beyond the obvious gains from a four-fold increase in energy density, these sulfur-based batteries could play a key role in electric vehicles and airplanes, where the flammability of lithium-ion batteries is a serious concern.