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Yoshimoto, Masataka*; Tamura, Kazuhisa; Watanabe, Kenta*; Shimizu, Keisuke*; Horisawa, Yuhei*; Kobayashi, Takeshi*; Tsurita, Hanae*; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*
Sustainable Energy & Fuels (Internet), 8(6), p.1236 - 1244, 2024/03
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)Photo-rechargeable systems, which can efficiently convert and store solar energy into chemical energy within single devices, are essential to harness sunlight effectively. Photo-(de)intercalation plays a pivotal role in the functionality of photorechargeable systems. Nevertheless, the photo-(de)intercalation process has not been conclusively confirmed owing to potential interference from side reactions, such as the decomposition of liquid electrolytes and the elution of electrode materials. In this study, we successfully demonstrated photo-responsive Li
-deintercalation using an all-solid-state thin-film battery comprised of epitaxially-grown anatase TiO
doped with Nb (a-TiO:Nb) as the cathode. Under light irradiation, Li-deintercalation occurred and was subsequently reversibly intercalated into a-TiO:Nb during discharge.
Watanabe, Kenta*; Horisawa, Yuhei*; Yoshimoto, Masataka*; Tamura, Kazuhisa; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*
Nano Letters, 24(6), p.1916 - 1922, 2024/02
Times Cited Count：2 Percentile：95.46(Chemistry, Multidisciplinary)Electrochemistry has extended from reactions at solid/liquid interfaces to those at solid/solid interfaces. In this study, we achieve the stable photoelectrochemical reaction at the semiconductor-electrode/solid-electrolyte interface in Nb-doped anatase-TiO (a-TiO:Nb)/Li
PO
(LPO)/Li all-solid-state cell. The oxidative currents of a-TiO:Nb/LPO/Li increase upon light irradiation when a-TiO:Nb is located at a potential that is more positive than its flat-band potential. The photoelectrochemical reaction at the semiconductor/solid-electrolyte interface is driven by the same principle as that at semiconductor/liquid-electrolyte interfaces. Thus, we extend photoelectrochemistry to all-solid-state systems composed of solid/solid interfaces.
Sr
CoO at initial electrochemical process in an alkaline solutionMatsuzaki, Akira*; Hirayama, Masaaki*; Oguchi, Shoya*; Komo, Mamoru*; Ikezawa, Atsunori*; Suzuki, Kota*; Tamura, Kazuhisa; Arai, Hajime*; Kanno, Ryoji*
Electrochemistry (Internet), 90(10), p.107001_1 - 107001_8, 2022/10
Times Cited Count：0 Percentile：0.01(Electrochemistry)Oxygen reduction and evolution reactions (ORR and OER) of perovskite-type LaSrCoO were characterized using two-dimensional model electrodes with different reaction planes. Synthesized by pulsed laser deposition, these thin and flat electrodes can reveal the reaction plane dependence of the ORR activity. From steady-state polarization measurements in KOH (aq.), the ORR activity was the highest on the (001) film during the first ORR/OER cycle, and it decreased significantly during the second cycle. In-situ synchrotron X-ray diffraction clarified crystal structure changes in the bulk and surface regions of LaSrCoO, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the LaSrCoO surface partially decomposed upon reacting. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.
MnO cathode in an all-solid-state thin-film battery during cyclingHikima, 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：12 Percentile：66.55(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.
PO-modified LiRuO for lithium-rich layered rocksalt oxide cathodesTaminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Kim, K.-S.*; Tamura, Kazuhisa; Kanno, Ryoji*
Journal of Physical Chemistry C, 122(29), p.16607 - 16612, 2018/07
Times Cited Count：8 Percentile：30.74(Chemistry, Physical)Lithium-rich layered rocksalt oxides are promising cathode materials for lithium-ion batteries. We investigate the effects of surface modification by amorphous LiPO on the structures and electrochemical reactions in the surface region of an epitaxial LiRuO(010) film electrode. Structural characterization using SXRD, HAXPES, and NR shows that surface modification by LiPO resulted in the partial substitution of P for Li in the surface region of LiRuO. The modified (010) surface exhibits better rate capability at 20 C compared to the unmodified surface. 
surface XRD confirmed that highly reversible structural changes occurred at the modified surface during lithium (de)intercalation. These results demonstrate that this surface modification stabilizes the crystal structure in the surface region, and it can improve the rate capability of lithium-rich layered rocksalt oxide cathodes.
and their Zr-O surface modified electrodesAbe, Machiko*; Iba, Hideki*; Suzuki, Kota*; Minamishima, Hiroaki*; Hirayama, Masaaki*; Tamura, Kazuhisa; Mizuki, Junichiro*; Saito, Tomohiro*; Ikuhara, Yuichi*; Kanno, Ryoji*
Journal of Power Sources, 345, p.108 - 119, 2017/03
Times Cited Count：11 Percentile：38.39(Chemistry, Physical)The surface structure of the Li(Ni, Co, Mn)O electrode was studied during charge/discharge process using electrochemical methods and X-ray/Neutron scattering techniques. It was found that during charge/discharge process the coverage of spinel structure increased. The spinel structure has low electrochemical activity and is not involved in Li insertion/extraction. After the surface modification, it was found that the coverage of the spinel structure did not increase. Further, it was also found out that the Li concentration at the electrode/electrolyte interface increased.
surface under high voltage battery operationTaminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Tamura, Kazuhisa; Minato, Taketoshi*; Arai, Hajime*; Uchimoto, Yoshiharu*; Ogumi, Zempachi*; Kanno, Ryoji*
Journal of Power Sources, 307, p.599 - 603, 2016/03
Times Cited Count：34 Percentile：72.4(Chemistry, Physical)An epitaxial-film model electrode of LiCoO(104) was fabricated on SrRuO(100)/Nb:SrTiO(100) using pulsed laser deposition. The 50 nm thick LiCoO(104) film exhibited lithium (de-)intercalation activity with a first discharge capacity of 119 mAh g
between 3.0 and 4.4 V, followed by a gradual capacity fading with subsequent charge-discharge cycles. In contrast, a 3.2 nm thick LiPO-coated film exhibited a higher intercalation capacity of 148 mAh g with superior cycle retention than the uncoated film. In situ surface X-ray diffraction measurements revealed a small lattice change at the coated surface during the (de-)intercalation processes compared to the uncoated surface. The surface modification of LiCoO by the LiPO coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage.
Kanno, Ryoji*; Hirayama, Masaaki*; Suzuki, Kota*; Tamura, Kazuhisa
Hyomen Kagaku, 37(2), p.52 - 59, 2016/02
Batteries are a key technology in today's society. Since the lithium-ion configuration has been widely accepted, significant efforts have been devoted to attain high energy and power densities to produce an excellent energy storage system without any safety issue. To improve the reliability and power characteristics of batteries, deep insights into the reactions at the electrode/electrolyte interface are necessary. The model systems with epitaxial thin-film electrodes might be suitable for understanding these reactions. The in situ techniques for directly observing surface structural changes of the electrodes have been developed for surface X-ray scattering and neutron reflectivity techniques. These techniques are reviewed and future studies on the interfacial reaction in batteries will be discussed.
O epitaxial thin film electrode for lithium batteriesSuzuki, Kota*; Hirayama, Masaaki*; Kim, K.-S.*; Taminato, So*; Tamura, Kazuhisa; Son, J.-Y.*; Mizuki, Junichiro; Kanno, Ryoji*
Journal of the Electrochemical Society, 162(13), p.A7083 - A7090, 2015/08
Times Cited Count：12 Percentile：39.14(Electrochemistry)The effects of surface coatings on LiMnO were investigated using LiMnO epitaxial thin films with a thickness of 30 nm. Bare and surface-coated LiMnO epitaxial thin films were synthesized on SrTiO(111) substrates using a pulsed laser deposition method. The surface coating, which was formed using the solid electrolyte LiPO and had a thickness of 3 nm, improved the reversibility of the electrochemical reactions undergone by the LiMnO epitaxial thin films. The changes induced in the surface structure were maintained during battery operation; in contrast, the bare LiMnO thin film exhibited structural degradation and Mn dissolution. The structural changes induced in the coated electrode and the increase in its surface stability were intrinsic effects of the LiPO coating and improved the electrochemical performance of the LiMnO thin-film electrode.
RuO epitaxial film electrodes and 
surface X-ray analysisTaminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Kim, K.-S.*; Zheng, Y.*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*
Journal of Materials Chemistry A, 2(34), p.17875 - 17882, 2014/11
Times Cited Count：21 Percentile：55.29(Chemistry, Physical)The surface structure of a lithium-rich layered material and its relation to intercalation properties were investigated by synchrotron X-ray surface structural analyses using LiRuO epitaxial-film model electrodes with different lattice planes of (010) and (001). Electrochemical charge-discharge measurements confirmed reversible lithium intercalation activity through both planes, corresponding to three-dimensional lithium diffusion within the LiRuO. The (001) plane exhibited higher discharge capacities compared to the (010) plane under high rate operation (over 5 C). Direct observations of surface structural changes by surface X-ray diffraction (XRD) and surface X-ray absorption near edge structure (XANES) established that an irreversible phase change occurs at the (010) surface during the first (de)intercalation process, whereas reversible structural changes take place at the (001) surface.
Ti
O
(110) film electrode for lithium batteriesKim, K.-S.*; Tojigamori, Takeshi*; Suzuki, Kota*; Taminato, So*; Tamura, Kazuhisa; Mizuki, Junichiro; Hirayama, Masaaki*; Kanno, Ryoji*
Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 80(10), p.800 - 803, 2012/10
Times Cited Count：13 Percentile：29.85(Electrochemistry)Electrochemical properties and structure changes of nano-sized LiTiO during lithium (de)intercalation wereinvestigated using a two-dimensional thin film electrode. LiTiO thin films were deposited on a Nb:SrTiO(110)substrate by a pulsed laser deposition technique. In situ X-ray diffraction measurements clarified the drastic structural changes of the LiTiOfilm upon soaking in the electrolyte and during the first intercalation and deintercalation processes. The surfaceregion of LiTiO had a different structure from the bulk during electrochemical cycling and could cause the nanosizedLiTiO electrodes to have high capacities and poor stabilities.
in comparison with undoped UO, Mg-Nb doped UO and Ti doped UOFujino, Takeo*; Shiratori, Tetsuo; Sato, Nobuaki*; Fukuda, Kosaku; Yamada, Kota*; Suzuki, Yasufumi; Serizawa, Hiroyuki
Journal of Nuclear Materials, 297(2), p.176 - 205, 2001/08
Times Cited Count：20 Percentile：79.11(Materials Science, Multidisciplinary)no abstracts in English
Kametaka, Masao*; Okazaki, Kazuhiko*; Nakayama, Kazuhiko; Seshimo, Kazuyoshi; Aoki, Kazuhiro; Tanaka, Yoshihiro; Shimada, Koji; Suzuki, Kazushige*; Shimogama, Kota*; Inada, Noriyuki*
no journal, ,
The evaluation of an fault activity has been done by an observation of deformation of overlying strata of the fault. However, it is difficult to evaluate the activity where the fault zone appears only in a basement rock with no overlying strata. We have been carried out the observation of the fault zone to establish the method of evaluation of fault activity. We selected the outcrops through literature and surface geological survey. Examples of outcrops of active fault are outcrops of Gosukebashi Fault in the Rokko-Awaji Fault Zone and the Rokko Fault in the Arima-Takatsuki Tectonic Line, southern Hyogo Prefecture. An example of non-active fault is outcrop of the fault around the Rokko Horai-kyo in the northern Rokko Mountains. In this study, we focus on the easy evaluation method in the field, and described about suitability of observation of fault plane, in-situ experiments of hardness and color.
SrCoOHirayama, Masaaki*; Matsuzaki, Akira*; Ikezawa, Atsunori*; Suzuki, Kota*; Arai, Hajime*; Kanno, Ryoji*; Tamura, Kazuhisa
no journal, ,
Oxygen reduction and evolution reactions (ORR and OER) of perovskite-type LaSrCoO were characterized using two-dimensional model electrodes with different reaction planes. Synthesized by pulsed laser deposition, these thin and flat electrodes can reveal the reaction plane dependence of the ORR activity. From steady-state polarization measurements in KOH (aq.), the ORR activity was the highest on the (001) film during the first ORR/OER cycle, and it decreased significantly during the second cycle. In-situ synchrotron X-ray diffraction clarified crystal structure changes in the bulk and surface regions of LaSrCoO, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the LaSrCoO surface partially decomposed upon reacting. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.
