Lithium germanium phosphorus sulfide solid electrolyte powder is a ceramic electrolyte with high ionic conductivity. Li₁₀GeP₂S₁₂ (LGPS) is a white powder that crystallizes in the P42/nmc space group with three-dimensional interconnecting channels of Li+ ions that allow for fast Li+ diffusion. It belongs to the class of sulfide electrolytes and should be handled in a glovebox because LGPS is sensitive to air and moisture.

Li10GeP₂S₁₂ (LGPS) is a solid electrolyte powder used in all-solid-state lithium batteries. It has an extremely high ionic conductivity of 12 mS cm^–1 which is even higher than those of organic liquid electrolytes currently used in practical lithium-ion batteries. Typically, scientists pelletize (cold-press) the powder and may optionally anneal the pellet at high temperature (550 C) to enhance the ionic conductivity. LGPS is unstable against Li metal and is often used as the catholyte.