Investigating electrochemical reactions in ionic liquids

In the Department of Applied Chemistry at Keio University's Faculty of Science and Technology, the Katayama Laboratory is doing research in the field of electrochemistry.

One aspect of the Lab's research is investigating electrochemical reactions in electrolytes called ionic liquids, and applying them to technologies, including new batteries and electroplating.

"Firstly, an ionic liquid is a liquid that consists only of ions. Ordinary electrolytic fluids, the electrolytes used in electrochemistry, are made by dissolving solid salts in solvents such as water. But ionic liquids don't use such solvents at all; they're liquids that consist only of ions. Even solids like sodium chloride become liquids at high temperatures, and those are called molten salts. In that case, though, they don't usually become liquids unless the temperature is several hundred degrees C. But ionic liquids are liquids even at room temperature. So, we're talking about salts like that."

The characteristics of these ionic liquids are: they have low volatility, and although they are organic salts, they don't burn easily.

Using ionic liquids in applications such as batteries is expected to result in devices that can store energy very safely.

"Research on ionic liquids is being done worldwide. But much of that research is on the characteristics of ionic liquids themselves: investigating their properties, or discovering new ionic liquids. We've narrowed our target down to ionic liquids that also seem to have practical utility. In this context, a feature of our research is: We look at, for example, redox reactions involving various metal ions, and we investigate their dynamic characteristics in detail using electrolytic methods."

The Katayama Laboratory also aims to develop very safe batteries with high output and long life, by using ionic liquids in redox flow cells, a form of storage battery that's considered promising in the energy field.

"I think electrochemistry is a discipline that's quite hard to understand, even compared with chemistry in general. If you're going to do electrochemistry, it's very important to have a good knowledge of physical chemistry, which is the basis of electrochemistry. So, I'd like students to thoroughly master the basics of physical chemistry before they tackle topics in electrochemistry."