Sodium bis(trifluoromethanesulfonyl)imide, abbreviated NaTFSI, is a white, crystalline salt. It is hygroscopic and deliquescent and usually stored under inert atmosphere. NaTFSI is soluble in water, carbonates (including dimethyl carbonate, diethyl carbonate, and propylene carbonate), acetonitrile, triglyme, dimethoxyethane, trimethyl phosphate, and many of the solvents commonly used in batteries.

The primary application of NaTFSI is as an electrolytic salt in sodium-ion batteries. Researchers have found that NaTFSI dissolved in organic solvents[1] and, more recently, in ionic liquids[2,3] serve as high-performing electrolytes with a broad operating voltage exceeding 3 V. In addition, in the application of solid electrolytes for sodium-ion batteries, NaTFSI is often added to poly(ethylene oxide)-ceramic composites because it increases the ionic conductivity of the composite.[4,5]