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Hikima, Kazuhiro*; Hinuma, Yoyo*; Shimizu, Keisuke*; Suzuki, Kota*; Taminato, So*; Hirayama, Masaaki*; Masuda, Takuya*; Tamura, Kazuhisa; Kanno, Ryoji*
ACS Applied Materials & Interfaces, 13(6), p.7650 - 7663, 2021/02
Times Cited Count:16 Percentile:66.78(Nanoscience & Nanotechnology)We evaluated the structural change of the cathode material LiMnO
that was deposited as an epitaxial film with an (001) orientation in an all-solid-state battery. In case of the electrode with LiPO
coating. Experiments revealed a structural change to a high-capacity (activated) phase that proceeded gradually and continuously with cycling. The activated phase barely showed any capacity fading. We propose a mechanism of structural change with cycling: charging to a high voltage at a sufficiently low Li concentration typically induces irreversible transition to a phase detrimental to cycling that could, but not necessarily, be accompanied by the dissolution of Mn and/or the release of O into the electrolyte, while a gradual irreversible transition to an activated phase happens at a similar Li concentration under a lower voltage.
Fugane, Keisuke*; Mori, Toshiyuki*; Yan, P.*; Masuda, Takuya*; Yamamoto, Shunya; Ye, F.*; Yoshikawa, Hideki*; Auchterlonie, G.*; Drennan, J.*
ACS Applied Materials & Interfaces, 7(4), p.2698 - 2707, 2015/02
Times Cited Count:31 Percentile:65.91(Nanoscience & Nanotechnology)no abstracts in English
Okawa, Yukihisa*; Masuda, Takuya*; Uehara, Hiromitsu*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Uosaki, Kohei*
RSC Advances (Internet), 3(35), p.15094 - 15101, 2013/09
Times Cited Count:9 Percentile:34.56(Chemistry, Multidisciplinary)Masuda, Takuya*; Fukumitsu, Hitoshi*; Kondo, Toshihiro*; Naohara, Hideo*; Tamura, Kazuhisa; Sakata, Osami*; Uosaki, Kohei*
Journal of Physical Chemistry C, 117(23), p.12168 - 12171, 2013/06
Times Cited Count:21 Percentile:52.63(Chemistry, Physical)The structure of the perfluorosulfonated ionomer (PFSI)/Pt(111) interface in a membrane electrode assembly (MEA)-like configuration of a polymer electrolyte membrane (PEM) fuel cell, that is, a vacuum evaporated Pt layer/PEM(Nafion membrane)/PFSI(adhesion Nafion layer)/Pt(111) single crystal, and its bias-induced change were investigated by surface X-ray scattering measurement at an atomic level. Crystal truncation rod measurement shows that PFSI adsorbed on the Pt(111)-(11) surface without bias. When the Pt(111) electrode was positively biased to form Pt oxide, the PFSI layer was detached from the Pt surface and oxygen atoms penetrated into the Pt lattice.
Masuda, Takuya*; Fukumitsu, Hitoshi*; Fugane, Keisuke*; Togasaki, Hirotaka*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Yoshikawa, Hideki*; Kobayashi, Keisuke*; Mori, Toshiyuki*; et al.
Journal of Physical Chemistry C, 116(18), p.10098 - 10102, 2012/05
Times Cited Count:124 Percentile:93.64(Chemistry, Physical)In situ electrochemical X-ray absorption fine structure (XAFS) measurements were performed at the Pt L and Ce L
edges of the Pt-CeO
/C catalyst, which was prepared by a combined process of precipitation and coimpregnation methods, as well as at the Pt L
edge of the conventional Pt/C catalyst in oxygen-saturated H
SO
solution to clarify the role of CeO
in the reduction of the overpotential for the oxygen reduction reaction (ORR) at the Pt-CeO
nanocomposite compared with the conventional Pt/C catalyst. XAFS measurements clearly show that the enhancement of ORR activity is attributed to the inhibition of Pt oxide formation by the CeO
layer, of which Ce
was oxidized to Ce
instead of Pt at the Pt oxide formation potential.
Ikaida, Riku*; Sano, Kazuhiro*; Masuda, Yoshimi*; Sekikawa, Takuya; Ono, Yoshiaki*
no journal, ,
The superconductivity of SrTiO, which is used in solar cells and as a photocatalyst, is observed in systems doped with electrons such as Nb, but it also exhibits crystal instability due to doping, and the realization of superconductivity is in competition with doping and crystal instability. Since the crystal instability is not well understood, we calculated the electronic structure of SrTiO
with electron doping as a parameter using the first-principles calculation software Quantum ESPRESSO. As a result, we succeeded in obtaining a solution for the decrease in frequency of crystal vibration (softening), which is considered to be caused by the ferroelectric transition, by reducing the amount of electron doping, and at the same time, we obtained the result that the superconducting transition temperature increases. This result is consistent with the experimental results of previous studies. This study provides new insight into the mechanism of superconductivity in SrTiO
, which has been an unsolved problem for many years.
Fugane, Keisuke*; Mori, Toshiyuki*; Wu, Y. Y.*; Yamamoto, Shunya; Maekawa, Yasunari; Yoshikawa, Hideki*; Yamashita, Yoshiyuki*; Ueda, Shigenori*; Vladimir, M.*; Suzuki, Akira*; et al.
no journal, ,
no abstracts in English
Fugane, Keisuke*; Mori, Toshiyuki*; Masuda, Takuya*; Uosaki, Kohei*; Yamamoto, Shunya; Maekawa, Yasunari
no journal, ,
no abstracts in English