Researchers investigate mechanics of lithium sulfides, which show promise as solid electrolytes
(PHYSorg.com Chemistry)

Most batteries are composed of two solid, electrochemically active layers called electrodes, separated by a polymer membrane infused with a liquid or gel electrolyte. But recent research has explored the possibility of all-solid-state batteries, in which the liquid (and potentially flammable) electrolyte would be replaced by a solid electrolyte, which could enhance the batteries` energy density and safety.