Shinya Shiotani
Toyota
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Featured researches published by Shinya Shiotani.
Scientific Reports | 2016
Sou Taminato; Masao Yonemura; Shinya Shiotani; Takashi Kamiyama; Shuki Torii; Miki Nagao; Yoshihisa Ishikawa; Kazuhiro Mori; Toshiharu Fukunaga; Yohei Onodera; Takahiro Naka; Makoto Morishima; Yoshio Ukyo; Dyah S. Adipranoto; Hajime Arai; Yoshiharu Uchimoto; Zempachi Ogumi; Kota Suzuki; Masaaki Hirayama; Ryoji Kanno
Among the energy storage devices for applications in electric vehicles and stationary uses, lithium batteries typically deliver high performance. However, there is still a missing link between the engineering developments for large-scale batteries and the fundamental science of each battery component. Elucidating reaction mechanisms under practical operation is crucial for future battery technology. Here, we report an operando diffraction technique that uses high-intensity neutrons to detect reactions in non-equilibrium states driven by high-current operation in commercial 18650 cells. The experimental system comprising a time-of-flight diffractometer with automated Rietveld analysis was developed to collect and analyse diffraction data produced by sequential charge and discharge processes. Furthermore, observations under high current drain revealed inhomogeneous reactions, a structural relaxation after discharge, and a shift in the lithium concentration ranges with cycling in the electrode matrix. The technique provides valuable information required for the development of advanced batteries.
Scientific Reports | 2016
Koji Ohara; Akio Mitsui; Masahiro Mori; Yohei Onodera; Shinya Shiotani; Yukinori Koyama; Yuki Orikasa; Miwa Murakami; Keiji Shimoda; Kazuhiro Mori; Toshiharu Fukunaga; Hajime Arai; Yoshiharu Uchimoto; Zempachi Ogumi
The atomic and electronic structures of binary Li2S-P2S5 glasses used as solid electrolytes are modeled by a combination of density functional theory (DFT) and reverse Monte Carlo (RMC) simulation using synchrotron X-ray diffraction, neutron diffraction, and Raman spectroscopy data. The ratio of PSx polyhedral anions based on the Raman spectroscopic results is reflected in the glassy structures of the 67Li2S-33P2S5, 70Li2S-30P2S5, and 75Li2S-25P2S5 glasses, and the plausible structures represent the lithium ion distributions around them. It is found that the edge sharing between PSx and LiSy polyhedra increases at a high Li2S content, and the free volume around PSx polyhedra decreases. It is conjectured that Li+ ions around the face of PSx polyhedra are clearly affected by the polarization of anions. The electronic structure of the DFT/RMC model suggests that the electron transfer between the P ion and the bridging sulfur (BS) ion weakens the positive charge of the P ion in the P2S7 anions. The P2S7 anions of the weak electrostatic repulsion would causes it to more strongly attract Li+ ions than the PS4 and P2S6 anions, and suppress the lithium ionic conduction. Thus, the control of the edge sharing between PSx and LiSy polyhedra without the electron transfer between the P ion and the BS ion is expected to facilitate lithium ionic conduction in the above solid electrolytes.
RSC Advances | 2014
Masafumi Nose; Kunihiro Nobuhara; Shinya Shiotani; Hideki Nakayama; Shinji Nakanishi; Hideki Iba
Electrochemically Na+-extracted Na4−xCo3(PO4)2P2O7 exhibits both Li+ and Na+ insertion capabilities. Given these compatibilities, novel hybrid-ion batteries were demonstrated by combining a Na4Co3(PO4)2P2O7 positive electrode and Li4Ti5O12 negative electrode in a lithium-based electrolyte.
Journal of Physical Chemistry Letters | 2018
Yuki Kato; Shinya Shiotani; Keisuke Morita; Kota Suzuki; Masaaki Hirayama; Ryoji Kanno
We report the preparation of thick electrode all-solid-state lithium-ion cells in which a large geometric capacity of 15.7 mAh cm-2 was achieved at room temperature using a 600 μm-thick cathode layer. The effect of ionic conductivity on the discharge performance was then examined using two different materials for the solid electrolyte. Furthermore, important morphological information regarding the tortuosity factor was electrochemically extracted from the capacity-current data. The effect of tortuosity on cell performance was also quantitatively discussed.
Scientific Reports | 2017
Shinya Shiotani; Koji Ohara; Hirofumi Tsukasaki; Shigeo Mori; Ryoji Kanno
In general, the ionic conductivity of sulfide glasses decreases with their crystallization, although it increases for a few sulphide glasses owing to the crystallization of a highly conductive new phase (e.g., Li7P3S11: 70Li2S-30P2S5). We found that the ionic conductivity of 75Li2S-25P2S5 sulfide glass, which consists of glassy and crystalline phases, is improved by optimizing the conditions of the heat treatment, i.e., annealing. A different mechanism of high ionic conductivity from the conventional mechanism is expected in the glassy phase. Here, we report the glassy structure of 75Li2S-25P2S5 immediately before the crystallization by using the differential pair distribution function (d-PDF) analysis of high-energy X-ray diffraction. Even though the ionic conductivity increases during the optimum annealing, the d-PDF analysis indicated that the glassy structure undergoes no structural change in the sulfide glass-ceramic electrolyte at a crystallinity of 33.1%. We observed the formation of a nanocrystalline phase in the X-ray and electron diffraction patterns before the crystallization, which means that Bragg peaks were deformed. Thus, the ionic conductivity in the mixture of glassy and crystalline phases is improved by the coexistence of the nanocrystalline phase.
Electrochemistry Communications | 2013
Masafumi Nose; Shinya Shiotani; Hideki Nakayama; Kunihiro Nobuhara; Shinji Nakanishi; Hideki Iba
Journal of Power Sources | 2016
Shinya Shiotani; Takahiro Naka; Makoto Morishima; Masao Yonemura; Takashi Kamiyama; Yoshihisa Ishikawa; Yoshio Ukyo; Yoshiharu Uchimoto; Zempachi Ogumi
Journal of Physical Chemistry C | 2015
Miwa Murakami; Keiji Shimoda; Shinya Shiotani; Akio Mitsui; Koji Ohara; Yohei Onodera; Hajime Arai; Yoshiharu Uchimoto; Zempachi Ogumi
Solid State Ionics | 2018
Hirofumi Tsukasaki; Shigeo Mori; Shinya Shiotani; Hideyuki Yamamura
Journal of Power Sources | 2017
Hirofumi Tsukasaki; Shigeo Mori; Shinya Shiotani; Hideyuki Yamamura; Hideki Iba