Electrochemical devices find application in many technologies, including batteries, capacitors, sensors, and transistors. For such electrochemical devices to function, they require an electric field to drive ion transport and electrochemical processes. This simple yet strict rule has long hindered innovation in electrochemistry and related technologies; however, researchers at WPI-MANA ​​recently challenged this rule with their development of "magnetic control of electrochemical devices.".
WPI-MANA ​​researchers Takashi Tsuchiya and Kazuya Terabe and their collaborators used a small magnet, rather than electrical equipment, to propel the ions. The transport of paramagnetic FeCl4 ions in a liquid electrolyte (containing [Bmim]FeCl4) was magnetically controlled to operate a typical electrochemical device: an electrical double-layer transistor (EDLT), a type of transistor that uses an electrical double-layer (EDL) at a semiconductor/electrolyte interface to tune the electron carrier density of the semiconductor. The electrical conductance of a two-dimensional hole (several nanometers thick) at a single crystal/diamond electrolyte interface (100) was successfully switched by a magnetic field, although the switching ratio was lower than in conventional electrically field-controlled EDLTs.
Magnetic ion control adds a new dimension to the nanoelectronics achieved by the ion paradigm, pioneered at WPI-MANA ​​as the atomic switch*, and such control has a significant impact, even on other electrochemical devices. It has the potential to enable innovative applications that have not been possible using conventional approaches. Furthermore, this discovery stimulates the development of high-performance magnetic electrolytes to support such innovation.
In electrochemistry, a branch of chemistry that has already been extensively studied, the interdisciplinary field of magnetism is one of the few remaining frontiers. Researchers will undoubtedly be drawn to it, like iron sand to a magnet.
 
* Reference
“Quantized Conductance Atomic Switch” K. Terabe, T. Hasegawa, T. Nakayama and M. Aono, Nature 433, 47-50 (2005), “Atomic Switch Reaching Outer Space”. 31 (2017)
Reference
T. Tsuchiya, M. Imura, Y. Koide and K. Terabe. Magnetic Control of Magneto-Electrochemical Cell and Electric Double Layer Transistor. Sci. Rep. 7, 10534 (2017).

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