TFSI

TFSI is an acronym with multiple widely used meanings in different fields, most commonly in automotive engineering and chemistry. The intended meaning depends on the context.

Turbocharged Fuel Stratified Injection refers to a designation used by the Volkswagen Group for gasoline engines that combine turbocharging with direct fuel injection. The term emphasizes the combination of a turbocharger with direct injection to improve power output and fuel efficiency. TFSI engines have appeared across Audi, Volkswagen, Skoda, and Seat models since the mid-2000s, with variants including several 2.0-liter and other displacement engines. In some markets the marketing name TSI is used for similar turbocharged direct-injection designs, though the exact branding can vary.

Bis(trifluoromethanesulfonyl)imide refers to the TFSI anion, a bulky, delocalized anion used in chemistry and materials science. The anion, [N(SO2CF3)2]−, is a component of many ionic liquids and of salts such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). TFSI-based species are valued for their high thermal stability, wide electrochemical window, and good ionic conductivity, making them common in research and applications related to electrochemistry, energy storage, and advanced electrolytes. In this context, TFSI is encountered as the counter anion to various organic cations in room-temperature ionic liquids and as an electrolyte component in lithium- and sodium-based batteries.

Because the acronym TFSI has distinct meanings, it is important to rely on context to determine the intended reference.