Lithium tetrachloroaluminate (LAC, lithium aluminium chloride) is an inorganic compound, a tetrachloroaluminate of lithium, with the formula LiAlCl4.
Solution of lithium tetrachloroaluminate in thionyl chloride is the liquid cathode and electrolyte of some lithium batteries, e.g. the lithium-thionyl chloride cell. Another cathode-electrolyte formulation is lithium tetrachloroaluminate+thionyl chloride+sulfur dioxide+bromine.
Lithium batteries with electrolytes based on lithium tetrachloroaluminate tend to have substantial voltage delays after high temperature storage followed with discharge at low temperature.
Other salts used in lithium battery electrolytes are lithium bromide, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluorophosphate; less common ones are lithium chloride, lithium iodide, lithium chlorate, lithium nitrate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium bis(trifluoromethanesulfonyl)imide, and lithium trifluoromethanesulfonate.