(Applied Physical Chemistry)
(b.1964), B.S.(1990,Waseda), Ph.D.(1995, Waseda), Post. Doc. Resercher (1996, U. of Minnesota), Assoc. Prof.(2010, Waseda), Prof.(2011, Waseda).
The Electrochemical Society of Japan Award for Young Electrochemists (2001), Electrochemistry Communications Award 2007 (2007).
Electrochemical Energy Devices / Electrochemistry / Electrochemical Impedance Analysis
3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
In order to realize future energy devices, fundamental and practical investigations are promoted for the development of materials and their interfaces and structures for electrochemical energy devices, including the design of rechargeable batteries and fuel cells. Because device performance is strongly influenced by electrochemical interfaces, as well as the materials in the energy device, electrochemical measurement methods are also studied.
To realize advanced electrochemical power supplies for portable equipment, some issues should be taken into account, i.e., 1) highly effective electrochemical reactions, 2) lower energy loss caused by internal resistance, 3) longer life, 4) guaranteed safety, and 5) cost of production.
Secondary batteries using Li metallic anodes are strongly demanded as a type of battery with high energy density for the future. It is necessary to improve or develop the materials used in metallic anode batteries to ensure safety during their operation. The interface between the anode and the electrolyte is investigated to modify it via additives or other techniques. Promising additives, as well as solvents for electrolytes, are also surveyed to realize a secondary battery using metallic Li anode that is safe and has a long life. Solid polymer electrolytes are also introduced. Some Li-alloy anodes are also investigated for ensuring safety and a longer life compared to conventional anode materials. Research on Li or Li alloy anodes requires the characterization of the interface, where the charge transfer reaction takes place.
At the interface, the so-called Solid Electrolyte Interphase (SEI) layer is formed by the reaction of the anode and electrolyte. The performance of anodes depends strongly on the characteristics of the SEI. The SEI should be permeable for the Li+ ion and prevent further sub-reactions between the anode material and electrolyte components. The elemental analysis and electrochemical characterization of SEIs is performed in order to understand the nature of SEIs, and for designing the SEI for anodes in future Li batteries. Based on the results related to SEIs, novel materials containing Si or Sn elements are designed. The simultaneous reactions of the metal deposition and the decomposition of organic electrolytes results in the deposition of a matrix, which has similar content with SEIs, with metallic elements. The deposits of Sn-O-C and Si-O-C were realized and found to reveal performances as anodes for Li batteries. In particular, the Si-O-C composite was revealed to show a long cycle life for thousands of cycles with high reversible capacity as an anode.
The three-phase boundary of fuel cells, where the reaction generates electric energy, is a sophisticated interface. The structure of the three-phase boundary - as well as the transporting pathway of electrons, ions, and gases - is characterized by electrochemical methods. The mechanism of the degradation in fuel cell performance is discussed with electrochemical responses for the further improvement of fuel cells.
Fig. SEM image of the microabsorber array for X-Ray imaging sensor device
fabricated by the electrodeposition process.
Fig. SEM images for the patterned magnetic nanodots formed by electroless
Fig. Representative TMAFM image of Cu nano dot array electrochemically fabricated on the silicon wafer surface.
(1) "Electrodeposited Novel Highly Durable SiOC Composite Anode for Li Battery Above Several Thousands of Cyclest", Electrochem. Commun., 13, 969-972 (2011).
(2) "Effect of the Atmosphere on Chemical Composition and Electrochemical Properties of Solid Electrolyte Interface on Electrodeposited Li Metal", J. Power Sources, 196, 6483-6487 (2011).
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