Precursor to lithium hexafluorophosphate for batteries Lithium fluoride is reacted with
hydrogen fluoride (HF) and
phosphorus pentachloride to make
lithium hexafluorophosphate , an ingredient in
lithium ion battery electrolyte. The lithium fluoride alone does not absorb
hydrogen fluoride to form a
bifluoride salt.
In molten salts Fluorine is produced by the
electrolysis of molten
potassium bifluoride. This electrolysis proceeds more efficiently when the electrolyte contains a few percent of LiF, possibly because it facilitates formation of an Li-C-F interface on the carbon
electrodes. (See also
magnesium fluoride.) Lithium fluoride is used also as a
diffracting crystal in X-ray spectrometry.
Radiation detectors It is also used as a means to record
ionizing radiation exposure from
gamma rays,
beta particles, and
neutrons (indirectly, using the Lithium-6| (n,alpha)
nuclear reaction) in
thermoluminescent dosimeters. 6LiF nanopowder enriched to 96% has been used as the neutron reactive backfill material for microstructured semiconductor neutron detectors (MSND).
Nuclear reactors Lithium fluoride (highly enriched in the common isotope lithium-7) forms the basic constituent of the preferred fluoride salt mixture used in
liquid-fluoride nuclear reactors. Typically lithium fluoride is mixed with
beryllium fluoride to form a base solvent (
FLiBe), into which fluorides of uranium and thorium are introduced. Lithium fluoride is exceptionally chemically stable and LiF/ mixtures (
FLiBe) have low melting points () and the best neutronic properties of fluoride salt combinations appropriate for reactor use.
MSRE used two different mixtures in the two cooling circuits.
Cathode for PLED and OLEDs Lithium fluoride is widely used in
PLED and
OLED as a
coupling layer to enhance
electron injection. The thickness of the LiF layer is usually around 1
nm. The
dielectric constant (or relative permittivity, ε) of LiF is 9.0. ==Natural occurrence==