Solid-state battery - Wikipedia
https://en.wikipedia.org/wiki/Solid-state_batteryBetween 1831 and 1834, Michael Faraday discovered the solid electrolytes silver sulfide and lead(II) fluoride, which laid the foundation for solid-state ionics. By the late 1950s, several electrochemical systems employed solid electrolytes. They used a silver ion, but had some undesirable qualities, including low energy density and cell voltages, and high internal resistance. A new class of solid-state electrolyte, developed by the Oak Ridge National L…