The development of lithium-ion batteries has energized studies of solid-state batteries, because the non-flammability of their solid electrolytes offers a fundamental solution to safety concerns. Since poor ionic conduction in solid electrolytes is a major drawback in solid-state batteries, such studies have been focused on the enhancement of ionic conductivity. The studies have identified some high performance solid electrolytes; however, some disadvantages have remained hidden until their use in batteries. This paper reviews the development of solid electrolytes and their application to solid-state lithium batteries.
