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Function Design of Ceramics for Sustainable Society

Katsuro Hayashi's group tackles developments of ceramic materials for fields of energy, electronics, and environment with research approaches of processing, applications, and basic materials properties. Our goal is producing experts for this research field.

Development of new-type batteries and elemental materials (ceramic electrolyte, materials for porous electrodes)

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Concept of
mixed aqueous-aprotic sodium-air battery

To realize new-type batteries with high energy density and sodium-sulfur batteries with improved safety, which are requested for the future smart grid society, elemental technologies based on ceramic materials are developing. Our group has proposed originally "aqueous sodium-air battery", which is one of the promising designs for enhancing effective energy density, constructed proof-of-principle cells, and investigated its elemental components and their integration for improving total performances of the battery. Its elemental components are related to broad fields of chemistry such as fast sodium ion conducting ceramics, electrodes consisting of nanostructured carbons, oxides and metals, and organic electrolytes. Importance is placed on exploration for new excellent ion conducting ceramics materials, which are crucial for the success of the batteries.

Active-anion derived functional ceramics

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Measured crystal structure (left) and
application to an electron emission cathode (right)
of C12A7. 'electride'

12CaOx7Al2O3 (C12A7) and its derivative crystals have a unique nanoporous structure accommodating various anions including active species that are hardly present in usual environments. For example, those accommodating H- ions have a function of converting from an insulator to an electronic conductor by an ultraviolet-illumination. C12A7 'electride' which is accommodating electrons in the nanopores, acts as an excellent cathode for electron emissions and injections.

Sonoprocess for ceramics

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Sonoprocess-derived iron nanoparticles.

When a strong ultrasonic wave is applied to a liquid, bubbles are formed in it and then the bubbles vibrate. During shrinkage of the bubbles, a diabetic compression occurs, forming a momentary and local reaction field with high temperature and high pressure. Application of this reaction field for ceramic material processing is effective in terms of 1) induction of unusual reactions; 2) marked promotion of a slow reaction; and 3) controllability in microstructures of products. Application of this technique is expanding to various synthesis processes for high-performance materials including: nanocarbon by sonochemical polymerization of benzene-derivatives; amorphous metallic nanoparticles from metal carbonyls; magnetic nanoparticles in water-ethanol mixture solvent; and fluorescent microparticles by a new emulsion method.

Novel carbon materials and application to super-capacitor

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SEM images of synthesized carbon spheres
by hydrothermal treatment
of glucose aqueous solution.

Nanosize carbon spheres are available by simple processes such as hydrothermal treatment of glucose aqueous solution. The product are applicable to novel adsorbents and electrodes for super-capacitors. Synthetic process is developing to control the microstructure of carbon and to achieve the best performances as the capacitor electrodes.

Applied Fine Chemistry, Department of Applied Chemistry
Professor Katsuro Hayashi
Associate Professor Hirofumi Akamatsu
Assistant Professor George Hasegawa
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