What Is an Ion Gel?

An ion gel is a type of semi-solid compound that retains an electrical charge through the embedding of an ionic liquid into a polymer during a drying phase. It is a form of sol gel or xero gel that are part-liquid, part-solid matrices of compounds with unique properties in materials science. These materials are seen as potential energy storage mechanisms for fuel cells, for the construction of nanoscale electronic components such as transistors that are billionths of a meter in width, and more. Such materials offer the unique advantage at a microscopic scale of having a porous surface area that is vastly larger than their total mass, which makes them ideal candidates with which to bind volatile or electrically-charged elements.

Producing an ion gel is done through a refinement of the sol gel manufacturing process. A block copolymer, which is a combination of different plastic monomer compounds with unique physical and chemical characteristics, is put through a process of hydrolysis-condensation with an ionic-conducting liquid. Colloid particles in the mixture prevent it from completely solidifying, and instead it takes on a gel form. This makes accessing the charge of the ionic or other embedded compounds more practical and the material can serve as an electrolyte in the absence of water. The elastic properties of a solid in the form of the block copolymer plastics, and the properties of an electrically-conducting ionic liquid are merged into one compound.

The materials science uses of an ion gel polymer matrix are diverse. The material is capable of being reshaped, recharged, but yet is stable under various physical or chemical stress conditions. An ion gel can function at a temperature of up to 482° Fahrenheit (250° Celsius) and remain stable at temperatures as high as 662° Fahrenheit (350° Celsius) without degrading. Such gels can also be made from a diversity of precursor polymer-like compounds, though silane compounds commonly used in making sol gels such as alkoxysilane and halogenosilane are usually used. The ionic liquid can also be based on water referred to as an aqua gel, alcohol as an alco gel, or other chemicals such as carboxylic acid.

Aero gels are another branch of research in the study of ion gel compounds. They are also based on the sol gel manufacturing process and have an end product that includes an encased ionic gas such as hydrogen used for fuel cells. Common forms of aero gel familiar to consumers and industry include foams such as Styrofoam and urethane foam cushioning in furniture.

Among the applications of ion gel compounds as of 2011 in their various, liquid, gas, and semi-solid component forms are as luminescent solar concentrators; as dielectric materials for low-voltage, high-performance transistors; and in a diversity of advanced energy storage applications. Aero gel types of ion gels have the advantage of being roughly 95% gas and yet take on a solid form, earning them the label of the world's lightest solid. They are being researched as energy adsorbers, sensors, and strong catalytic compounds.