Kiyotaka Shigehara

Ionic conductivity of LiX-oligo(ethylene oxide)-perfluoro polymer ternary hybrids

Abstract Polymeric solid electrolytes were prepared from inorganic lithium salts, endo-acetylated oligo(ethylene oxide) and polyanions with perfluoro(ethylene) main chain. High ionic conductivity was found when these ternary hybrids took micro-segregated structures with continuous cylindrical conduction columns of lithium salt-oligo(ethylene oxide) in the sea of perfluoro-poly(electrolytes). The ionic conductivity of more than 10−5 S/cm was established at room temperature without affecting the processibility and flexibility of resulting hybrid films.

Virtues of a copolymer containing pyrrolidone and iron porphyrin groups in the catalysis of the reduction of dioxygen at graphite electrodes

Copolymerization of 1-vinyl-2-pyrrolidone with meso-[tri(phenyl)mono(p-methacrylamidophenyl)] porphine leads to a polymer that is insoluble but wetted and well swollen in aqueous media. Incorporation of Fe(III) in the porphine groups of the copolymer produced a metallopolymer which formed adherent coatings on graphite electrodes that were catalytically active toward the electro-reduction of dioxygen. Experiments with rotating disk and ring-disk electrodes demonstrated that a four-electron reduction of dioxygen to water results at sufficiently negative potentials. In addition, it was shown that, even with rather thick coatings, almost all of the Fe-porphine units in such coatings participate in the catalysis. However, the copolymeric catalyst suffers from the same instability exhibited by monomeric iron porphyrin catalysts in the presence of the hydrogen peroxide that is generated as an intermediate in the reduction of dioxygen.

Lithium Ion Conducting Polymeric Hybrids

Abstract Plastic solid electrolytes were prepared from inorganic lithium salts and polymer matrixes, and their ionic conductivity was discussed in relation to the ordering or the space distribution state of conduction column. When the hybrids took the micro-segregated structure with the continuous cylindrical conduction column embedded in supporting polymer matrixes, the ionic conductivity was enhanced. Thus formulated polymeric hybrids gave the ionic conductivity of 10–5 S/cm and excellent processibility.