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Yoneda, Yasuhiro; Yoshigoe, Akitaka; Takeda, Yukiharu; Shiwaku, Hideaki; Matsumura, Daiju; Shobu, Takahisa; Tamura, Kazuhisa
Materia, 58(12), p.763 - 769, 2019/12
This is an introduction to the equipment provided for each implementation period belonging to the structure analysis platform in the nanotechnology platform.
Akutsu, Kazuhiro*; Cagnes, M.*; Tamura, Kazuhisa; Kanaya, Toshiji*; Darwish, T. A.*
Physical Chemistry Chemical Physics, 21(32), p.17512 - 17516, 2019/08
Times Cited Count:2 Percentile:78.23(Chemistry, Physical)We combined the deuterium labeling and neutron reflectivity techniques to determine the fine structure of the electric double layer structure in an imidazolium ionic liquid (IL). For this, a simple and large scale deuteration method for imidazolium ILs was developed, where the deuteration level can be systematically controlled.
Kishi, Hirofumi*; Sakamoto, Tomokazu*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Kato, Takeshi*; Zulevi, B.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; Matsumura, Daiju; et al.
Nanomaterials (Internet), 8(12), p.965_1 - 965_13, 2018/12
Times Cited Count:4 Percentile:62.48(Nanoscience & Nanotechnology)Taminato, 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:5 Percentile:55.06(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 Li
RuO
(010) film electrode. Structural characterization using SXRD, HAXPES, and NR shows that surface modification by Li
PO
resulted in the partial substitution of P for Li in the surface region of Li
RuO
. 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.
Konishi, Hiroaki*; Hirano, Tatsumi*; Takamatsu, Daiko*; Gunji, Akira*; Feng, X.*; Furutsuki, Sho*; Okumura, Takafumi*; Terada, Shohei*; Tamura, Kazuhisa
Journal of Solid State Chemistry, 262, p.294 - 300, 2018/06
Times Cited Count:5 Percentile:42.14(Chemistry, Inorganic & Nuclear)The potential in each state of charge (SOC) during charging of LiNi
Mn
Co
O
is higher than that during discharging. To clarify the effect of chargedischarge operating conditions on the electrochemical reaction, Li
Ni
Mn
Co
O
was charged and discharged under various charge-discharge operating ranges, and OCP, crystal structure, and oxidation states of the ransition metals were evaluated by electrochemical measurement, XRD, and XAFS. These results indicate that OCP, lattice parameters, and oxidation states of the transition metals of Li
Ni
Mn
Co
O
in each SOC are not constant. The XRD results indicate that two phases, namely, LiNi
Mn
Co
O
-like and Li
MnO
-like, exist in Li
Ni
Mn
Co
O
.
Konishi, Hiroaki*; Hirano, Tatsumi*; Takamatsu, Daiko*; Gunji, Akira*; Feng, X.*; Furutsuki, Sho*; Okumura, Takafumi*; Terada, Shohei*; Tamura, Kazuhisa
Journal of Solid State Chemistry, 258, p.225 - 231, 2018/02
Times Cited Count:6 Percentile:35.14(Chemistry, Inorganic & Nuclear)LiNi
Mn
Co
O
is known as one of the cathode electrode material for Li ion batteries and its structure during charge and discharge process was investigated using electrochemical method and X-ray diffraction. It was found that in the charge process the structure changes in the order of Li
MnO
, LiNi
Mn
Co
O
, and Li
MnO
. On the other hand, in the discharge process, the structure changes in the order of Li
MnO
and LiNi
Mn
Co
O
.
Abe, 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:8 Percentile:50.02(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.
Sakamoto, Tomokazu*; Masuda, Teruyuki*; Yoshimoto, Koji*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Matsumura, Daiju; Tamura, Kazuhisa; Hori, Akihiro*; Horiuchi, Yosuke*; Serov, A.*; et al.
Journal of the Electrochemical Society, 164(4), p.F229 - F234, 2017/01
Times Cited Count:11 Percentile:36.36(Electrochemistry)Sakamoto, Tomokazu*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Matsumura, Daiju; Tamura, Kazuhisa; Hori, Akihiro*; Horiuchi, Yosuke*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; et al.
Journal of the Electrochemical Society, 163(10), p.H951 - H957, 2016/08
Times Cited Count:17 Percentile:29.03(Electrochemistry)Tamura, Kazuhisa; Nishihata, Yasuo
Journal of Physical Chemistry C, 120(29), p.15691 - 15697, 2016/07
Times Cited Count:7 Percentile:61.04(Chemistry, Physical)The behavior of halide ions on the Au(111) electrode surface in two ionic liquids (ILs) was investigated by monitoring the structure of the electrode surface. The potential dependences of the X-ray diffraction intensity, which originate from the Au(111)-(11) structure and the surface normal structure, were measured simultaneously with cyclic voltammograms. The results revealed that halide ions are co-adsorbed with IL molecules on the electrode surface and increase the mobility of surface atoms. This suggests that the interaction between halide ions and surface Au atoms is weaker than that between IL molecules and surface Au atoms; that is, the surface properties are mainly governed by adsorbed IL molecules. Furthermore, a comparison of the two ILs revealed that the effect of halide ions on the structure of the Au(111) electrode surface depends on the strength of the interaction between IL molecules and surface Au atoms.
Taminato, 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:21 Percentile:25.56(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 Li
PO
-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 Li
PO
coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage.
Sakamoto, Tomokazu*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo
Hyomen Kagaku, 37(2), p.78 - 83, 2016/02
We have developed direct liquid fuel anion exchange membrane fuel cell vehicles to deal with the global warming. Non-platinum group metals (PGM) catalyst has been researched to apply for both anode and cathode electrodes. A test driving was carried out for the fuel cell vehicle equipped with no precious metals as catalysts at SPring-8 in 2013. Here we introduce our results of advanced analysis for reaction mechanism and active site of non-PGM catalyst using synchrotron radiation X-rays at SPring-8.
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.
Suzuki, 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:8 Percentile:65.9(Electrochemistry)The effects of surface coatings on LiMnO
were investigated using LiMn
O
epitaxial thin films with a thickness of 30 nm. Bare and surface-coated LiMn
O
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 Li
PO
and had a thickness of 3 nm, improved the reversibility of the electrochemical reactions undergone by the LiMn
O
epitaxial thin films. The changes induced in the surface structure were maintained during battery operation; in contrast, the bare LiMn
O
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 Li
PO
coating and improved the electrochemical performance of the LiMn
O
thin-film electrode.
Sakamoto, Tomokazu*; Matsumura, Daiju; Asazawa, Koichiro*; Martinez, U.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; Tamura, Kazuhisa; Nishihata, Yasuo; Tanaka, Hirohisa*
Electrochimica Acta, 163, p.116 - 122, 2015/05
Times Cited Count:41 Percentile:16.42(Electrochemistry)Taminato, 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:18 Percentile:38.29(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 Li
RuO
. 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.
Asazawa, Koichiro*; Kishi, Hirofumi*; Tanaka, Hirohisa*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Saputro, A. G.*; Nakanishi, Hiroshi*; Kasai, Hideaki*; Artyushkova, K.*; et al.
Journal of Physical Chemistry C, 118(44), p.25480 - 25486, 2014/11
Times Cited Count:12 Percentile:51.71(Chemistry, Physical)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:8 Percentile:61.25(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:12 Percentile:53.03(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.
Kim, 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:11 Percentile:65.85(Electrochemistry)Electrochemical properties and structure changes of nano-sized LiTi
O
during lithium (de)intercalation wereinvestigated using a two-dimensional thin film electrode. Li
Ti
O
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 Li
Ti
O
film upon soaking in the electrolyte and during the first intercalation and deintercalation processes. The surfaceregion of Li
Ti
O
had a different structure from the bulk during electrochemical cycling and could cause the nanosizedLi
Ti
O
electrodes to have high capacities and poor stabilities.