Editorial
Preface for the 69th Special Feature — “Frontiers of Molten Salts and Ionic Liquids”
2024 Volume 92 Issue 4 Pages 043001
Details
2024 Volume 92 Issue 4 Pages 043001
The 69th special feature, titled “Frontiers of Molten Salts and Ionic Liquids,” will focus on the recent progress in the field of molten salts and ionic liquids. Molten salts include conventional high-temperature molten salts and room-temperature molten salts (more commonly referred to as ionic liquids), as well as molten metals, molten glasses, and molten hydrates in the broadest sense. In recent years, chemical and electrochemical reactions using molten salts and ionic liquids have become increasingly important for the realization of a carbon-neutral society. Major recent applications include storage batteries, green smelting, recycling, CO2 utilization, hydrogen production, and nuclear fuel reprocessing. In this special feature, readers will see how electrochemical processes in molten salts and ionic liquids hold promise for realizing a carbon-neutral society in the future.
When we refer to molten salts, most people probably think of high-temperature molten salts. On the other hand, when referring to ionic liquids, people generally think of salts in a liquid state at room temperature or at temperatures below 100 °C.1 Historically, however, a famous technical book has written that the rigid definition of the term “molten salt” implies an ionic liquid matrix.2 Also, salts in a liquid state at room temperature had been referred to as room-temperature molten salts.3,4 Namely, both molten salts and ionic liquids have nothing to do with melting points or working temperatures in their definitions. So, when discussing them in a scientific manner, like this special feature, there is much significance in taking them together without making a distinction between them. However, in experimental or practical applications, the handling can differ greatly depending on the temperature range, which is also very interesting.
In a broader sense, molten salts also include molten metals, molten glasses, and molten hydrates. Molten salt chemistry and technology are becoming increasingly important for the realization of a carbon-neutral society. Notable recent applications include batteries, green smelting, recycling, CO2 utilization, hydrogen production, nuclear power, pyrochemical reprocessing of nuclear fuel, and more. Therefore, we have planned a special feature on the recent progress on molten salts and ionic liquids.
This special feature is also closely related to the 2023 Joint Symposium on Molten Salts held at Kyoto Garden Palace in Kyoto, November 12–16, 2023, as shown in Photo 1, which was co-sponsored by Molten Salt Committee, The Electrochemical Society of Japan. This joint symposium includes three historical meetings on molten salts and ionic liquids: “12th International Conference on Molten Salt Chemistry and Technology” (since 1983), “8th Asian Conference on Molten Salt Chemistry and Technology” extended from “Japan-China Bilateral Conference on Molten Salt Chemistry and Technology” (since 1986), and “55th Symposium on Molten Salt Chemistry in Japan” (since 1958). There were 185 participants from 15 different countries, and 137 presentations were made. The symposium was a success, providing opportunities for many researchers to engage in enthusiastic discussions. From high-temperature molten salts to low-temperature ionic liquids, meaningful discussions were held based on common understanding and common issues concerning research methods, structural analysis, and application fields of molten salts.
A group photo of 2023 Join Symposium on Molten Salts held at Kyoto Garden Palace, Kyoto, Japan, November 12–16, 2023.
Below are some of the noteworthy titles among the papers included in this special feature. “Electrowinning of Aluminium. Challenges and Possibilities for Reducing the Carbon Footprint”,5 “Emerging Molten Salts Based Electrochemical Energy Technologies”,6 “In-Situ Raman Spectroscopic Analysis of Factors Improving Discharge Rate Capability of Na-Ion Batteries with FSA-Based Ionic Liquids”,7 “Lanthanide Silicide Formation on Si Electrode in LiCl-KCl Melt for Immobilization of Chloride Waste in Pyroprocessing of Nuclear Fuels”.8
The authors of this editorial article have joined the editorial board of Electrochemistry as guest editors for this special feature. We would like to thank the Editorial Board of Electrochemistry for their cooperation in the peer review and publication process.
Toshiyuki Nohira: Writing – original draft (Lead)
Yasushi Katayama: Writing – review & editing (Equal)
Takuya Goto: Writing – review & editing (Equal)
Tetsuya Tsuda: Writing – review & editing (Equal)
The authors declare no conflict of interest in the manuscript.
T. Nohira and Y. Katayama: ECSJ Fellows
T. Goto and T. Tsuda: ECSJ Active Members
Toshiyuki Nohira (Professor, Institute of Advanced Energy, Kyoto University)
Toshiyuki Nohira was born in 1970. He received his Ph.D. from Kyoto University in 1998. He worked as Assistant Professor (1998–) and Associate Professor (2007–) at Graduate School of Energy Science, Kyoto University. He was promoted to Professor of Institute of Advanced Energy, Kyoto University in 2015. He was awarded the Young Scientists’ Prize of the Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology of Japan (2009), and Scientific Achievement Award of The Electrochemical Society of Japan (2020). His research interests are electrochemical applications of molten salts and ionic liquids in the fields of materials science and energy science.
Yasushi Katayama (Professor, Faculty of Science and Technology, Keio University)
Yasushi Katayama was born in 1968. He graduated from the Graduate School of Engineering, Kyoto University in March 1996, and earned Doctor of Engineering. He was employed as Research Associate at Keio University and was promoted to Assistant Professor in 2001, Associate Professor in 2007, and Professor in 2014. He received Molten Salt Award from The Molten Salt Committee of the Electrochemical Society of Japan in 2018. His research interests include electrochemical applications of ionic liquids.
Takuya Goto (Vice-President, Professor, Faculty of Science and Technology, Doshisha University)
Takuya Goto was born in 1968. He received a doctorate in energy science from Kyoto Univ. in March 2004. He was employed as Assistant Professor at Keio Univ. in 1997, at Kyoto Univ. in 1998, then moved to Doshisha Univ. in 2009 as Associate Professor, and Professor in 2015, and Vice-President in 2024. He received Molten Salt Award from The Molten Salt Committee of the Electrochemical Society of Japan in 2023. His research interests include electrochemical applications of molten salts.
Tetsuya Tsuda (Professor, Graduate School of Science and Engineering, Chiba University)
Tetsuya Tsuda received his Ph.D. degree in Energy Science from Kyoto University in 2001. He started his academic career (research associate and research assistant professor) at The University of Mississippi under the direction of Professor Charles L. Hussey, who is one of the fathers of modern ionic liquid (IL) science. In 2008, he moved to Graduate School of Engineering, Osaka University and served as a tenure-track assistant professor and a tenured associate professor (2013.4–2022.3). In 2022, he was appointed as a professor at Chiba University. His research interests are energy science and materials science related to electrochemistry in IL.
