ionicliquid

Ionic liquids are salts that are liquid at relatively low temperatures, often at room temperature or below 100 °C. They are typically composed of bulky, asymmetric organic cations—such as imidazolium, pyridinium, or ammonium species—and a variety of anions, including tetrafluoroborate (BF4−), hexafluorophosphate (PF6−), bis(trifluoromethylsulfonyl)imide (NTf2−), or other organic or inorganic anions. A defining feature is their negligible vapor pressure, which minimizes volatile emissions, and their broad liquid range, allowing persistence of the liquid state across a wide temperature window.

The properties of ionic liquids are highly tunable through cation and anion choice. This modularity yields a wide range of behaviors, including high ionic conductivity, wide electrochemical windows, and substantial thermal stability. They are often nonflammable and have low volatility. They can act as good solvents for many organic and inorganic compounds and may be miscible with water or various organic solvents. However, they can exhibit high viscosities, and their properties depend on temperature and moisture content. Some ionic liquids can be toxic or persistent in the environment, and their synthesis may involve hazardous reagents, so life-cycle assessments are important.

Applications of ionic liquids span diverse areas. They are used as solvents in chemical synthesis, as catalysts or reaction media, and as electrolytes in batteries, supercapacitors, and fuel cells. They also find use in electroplating, separations and extractions, and as lubricants or heat transfer fluids in specialized settings. Ongoing research seeks to optimize performance, reduce cost, and better understand environmental impacts, while exploring new cation–anion combinations and functionalized ionic liquids for targeted tasks.