Lithium

Lithium is a material added by various mods.

Vanilla
on the Minecraft Wiki

IndustrialCraft 2
Tiny Pile of Lithium Dust can be obtained by processing in a. Despite there being an item named, it is currently unobtainable, making Lithium useless without other mods installed.

NuclearCraft
Lithium is a naturally occurring element that spawns as Lithium Ore between Y=0 and Y=32. It is used to produce many various items and alloys, including and various Lithium Ion batteries. Its isotopes can be used with other light elements in various recipes.