Fuji Developing Ionic Liquids for Rechargeable Batteries

September 07, 2016 by Jeff Shepard

Fuji Pigment Co., Ltd. has begun synthesizing ionic liquids that can be used in applications such as rechargeable aluminum-air batteries, solvents for cellulose nanofibers and electrolytes for lithium-ion batteries. Ionic liquids are new materials that have recently become the subject of a large amount of research and have seen gradual commercialization. An ionic liquid is a liquid material that completely consists of ions at temperatures below 100 degrees C. Various ionic liquids with different properties can be created by combining different cations and anions. They can therefore referred to as the "third liquid" in relation to water and organic solvents.

Ionic liquids remain in a liquid state over a wide temperature range, permitting their use in both high- and low-temperature conditions. These liquids are also thermally, chemically stable and exhibit low vapor pressure; they can therefore be used under extreme conditions such as a vacuum. In addition, ionic liquids are non-flammable and conductive.

Applications of ionic liquids are expected to include: 1. Creating the world's first practical, rechargeable aluminum–air battery by using an ionic liquid as the electrolyte. Fuji Pigment Co., Ltd. is attempting to create a rechargeable aluminum–air battery by replacing with an ionic liquid the aqueous electrolyte that is typically used. By using an ionic liquid such as 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium chloride as the electrolyte, it is possible to create a rechargeable aluminum–air battery.

2. Dissolution of cellulose and cellulose nanofibers. Ionic liquids are able to dissolve insoluble materials such as cellulose.

3. Use as an electrolyte for lithium-ion batteries and other types of batteries. LIBs using an ionic liquid as electrolyte are observed to have better electrochemical properties as compared with those using the conventional carbonate-based electrolyte. Ionic liquid electrolytes are also stable and non-flammable, countering the flammability of typical LIBs due to their carbonate-based electrolytes.

4. Formation of carbon nanotube dispersions and gels. Mixing carbon nanotubes with an ionic liquid allows the formation of a good dispersion with the resin, which is needed to create a gel that maintains the high conductivity and other interesting properties.

5. Use as an antistatic material. Because of their non-volatility and high heat resistance, ionic liquids can be mixed with resin in a high-temperature process. In particular, optimizing the ionic liquid's structure and compatibility with the resin results in a material that has excellent antistatic property, high transparency, and high conductivity.

6. Solvent for organic synthesis. Because of the urgent need for "green chemical processes", replacing the strongly volatile organic solvents used in syntheses with more environment-friendly solvents is necessary. Since ionic liquids exhibit almost no vapor pressure and non-flammable and safety, they have potential use in such processes. Furthermore, Ionic liquids can be easily reused and can be recyclcable many times because they can be separated from other liquids by heating, distilling, and other processes;

Ionic liquids can also be used as CO2-absorbing materials, wetting agents or lubricants that can be used under vacuum conditions, and additives for colored products, among various other applications.