Lithium hexafluorosilicate (Li₂SiF₆, CAS 17347-95-4) is an inorganic salt composed of lithium cations and hexafluorosilicate anions. It typically appears as a white crystalline powder and is soluble in water. Its primary and most significant application is in the field of energy storage, specifically as a precursor material for lithium-ion battery electrolytes. It serves as a source of both lithium ions and fluoride ions, which are crucial for forming a stable solid electrolyte interphase (SEI) layer on electrode surfaces. This function helps improve battery performance, cycle life, and safety. Consequently, it is a key material in the research and development of advanced battery technologies. Beyond its role in batteries, lithium hexafluorosilicate is also utilized in some industrial processes, such as aluminum production and as a component in certain ceramic glazes. It is classified as a hazardous substance, requiring careful handling due to its potential to release toxic and corrosive hydrogen fluoride (HF) upon decomposition or contact with acids.