ชRๅwยซวZ^[Acta Medica Okayama0917-1533141992าWใL82ENHiroyukiIshidaNo potential conflict of interest relevant to this article was reported.ชRๅwยซวZ^[Acta Medica Okayama0917-1533181996าWใL54ENHiroyukiIshidaNo potential conflict of interest relevant to this article was reported.Acta Medica Okayama16222006Properties of a novel hard-carbon optimized to large size Lion secondary battery studied by 7Li NMR13221328ENKazumaGotohMarikoMaedaAisakuNagaiAtsushiGotoMasatakaTanshoKenjiroHashiTadashiShimizuHiroyukiIshida<p>The state of lithium in a novel hard-carbon optimized to the anode of large size Li ion secondary battery, which has been recently commercialized, was investigated and compared with other existing hard-carbon samples by 7Li NMR method. The new carbon material showed a peak at 85 ppm with a shoulder signal at 7 ppm at room temperature in static NMR spectrum, and the former shifted to 210 ppm at 180 K. The latter at room temperature was attributed to Li doped in small particles contained in the sample. The new carbon sample showed weaker intensity of cluster-lithium signal than the other hard-carbon samples in NMR, which corresponded to a tendency of less "Constant Voltage" (CV) capacity in charge-discharge curves of electrochemical evaluation. Smaller CV capacity and initial irreversible capacity, which are the features of the novel hard-carbon, are considered to correspond to a blockade of the diffusion of Li into pore of carbon.</p>No potential conflict of interest relevant to this article was reported.Blackwell PublishingActa Medica Okayama0108-27016312007Hydrogen bonding in two solid phases of phenazine-chloranilic acid (1/1) determined at 170 and 93 Ko17o20ENKazumaGotohTetsuoAsajiHiroyukiIshidaThe crystal structures in two solid phases, i.e. phase II stable between 146 and 253 K and phase IV below 136 K, of the title compound [phenazine-chloranilic acid (1/1), C12H8N2 center dot C6H2Cl2O4, in phase II, and phenazinium hydrogen chloranilate, C12H9N2+center dot C6HCl2O4-, in phase IV], have been determined. Both phases crystallize in P2(1), and each structure was refined as an inversion twin. In phase II, the phenazine and chloranilic acid molecules are arranged alternately through two kinds of O-H center dot center dot center dot N hydrogen bonds. In phase IV, salt formation occurs by donation of one H atom from the chloranilic acid molecule to the phenazine molecule; the resulting monocation and monoanion are linked by N-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama6912008Observation of micropores in hard-carbon using Xe-129 NMR porosimetry147152ENKazumaGotohTakahiroUedaHironoriOmiTaroEguchiMarikoMaedaMichihisaMiyaharaNagaiAisakuHiroyukiIshida<p>The existence of micropores and the change of surface structure in pitch-based hard-carbon in xenon atmosphere were demonstrated using Xe-129 NMR. For high-pressure (4.0 MPa) Xe-129 NMR measurements, the hard-carbon samples in Xe gas showed three peaks at 27, 34 and 210 ppm. The last was attributed to the xenon in micropores (<1 nm) in hard-carbon particles. The NMR spectrum of a sample evacuated at 773 K and exposed to 0.1 MPa Xe gas at 773 K for 24 h showed two peaks at 29 and 128 ppm, which were attributed, respectively, to the xenon atoms adsorbed in the large pores (probably mesopores) and micropores of hard-carbon. With increasing annealing time in Xe gas at 773 K, both peaks shifted and merged into one peak at 50 ppm. The diffusion of adsorbed xenon atoms is very slow, probably because the transfer of molecules or atoms among micropores in hard-carbon does not occur readily. Many micropores are isolated from the outer surface. For that reason, xenon atoms are thought to be adsorbed only by micropores near the surface, which are easily accessible from the surrounding space.</p>No potential conflict of interest relevant to this article was reported.Pergamon-Elsevier Science Ltd.Acta Medica Okayama0008-62234782009The use of graphite oxide to produce mesoporous carbon supporting Pt, Ru, or Pd nanoparticles21202124ENKazumaGotohKojiKawabataEijiFujiiKunimitsuMorishigeTaroKinumotoYukiMiyazakiHiroyukiIshidaMesoporous carbon having platinum, ruthenium or palladium nanoparticles on exfoliated graphene sheets were produced from graphite oxide (GO) and metal complexes. The Pt included carbon was made by heating of the intercalation compound including tetraammineplatinum (II) chloride monohydrate. Samples having Ru or Pd are producible by heating in nitrogen gas atmosphere using hexaammineruthenium (III) chloride or tetraamminepalladium (II) chloride monohydrate instead of Pt complex. The particle sizes of platinum, ruthenium, and palladium were, respectively, 1–3, 1–2, and 3–7 nm. The platinum- or palladium-containing sample showed catalytic activity for oxygen reduction.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0008-62234942011Exfoliated graphene sheets decorated with metal / metal oxide nanoparticles: simple preparation from cation exchanged graphite oxide11181125ENKazumaGotohTaroKinumotoEijiFujiiAkiYamamotoHidekiHashimotoTakahiroOhkuboAtsushiItadaniYasushigeKurodaHiroyukiIshidaWe produced carbon hybrid materials of graphene sheets decorated with metal or metal oxide nanoparticles of gold, silver, copper, cobalt, or nickel from cation exchanged graphite oxide. Measurements using powder X-ray diffraction, transmission electron microscopy, and X-ray absorption spectra revealed that the Au and Ag in the materials (Au-Gr and Ag-Gr) existed on graphene sheets as metal nanoparticles, whereas Cu and Co in the materials (Cu-Gr and Co-Gr) existed as a metal oxide. Most Ni particles in Ni-Gr were metal, but the surfaces of large particles were partly oxidized, producing a core-shell structure. The Ag-Gr sample showed a catalytic activity for the oxygen reduction reaction in 1.0 M KOH aq. under an oxygen atmosphere. Ag-Gr is superior as a cathode in alkaline fuel cells, which should not be disturbed by the methanol cross-over problem from the anode. We established an effective approach to prepare a series of graphene-nanoparticle composite materials using heat treatment.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0008-622349122011Analysis of bis(trifluoromethylsulfonyl)imide-doped paramagnetic graphite intercalation compound using F-19 very fast magic angle spinning nuclear magnetic resonance40644066ENKazumaGotohKazuyukiTakedaMichael M.LernerYoshimiSueishiShinpeiMaruyamaAtsushiGotoMasatakaTanshoShinobuOhkiKenjiroHashiTadashiShimizuHiroyukiIshidaF atoms bonding to paramagnetic/conductive graphene layers in accepter-type graphite intercalation compounds (GICs) are analyzed using very fast magic angle spinning nuclear magnetic resonance, which is applied for the first time on F-19 nuclei to investigate paramagnetic materials. In the bis(trifluoromethylsulfonyl)imide(TFSI)-doped GIC, C-F bonds between fluorine atoms and graphene layers conform to a weak bonding of F to the graphene sheets. TFSI anions intercalated in the GIC do not show overall molecular motion; even at room temperature only the CF3 groups rotate.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0378-77532252013NMR study for electrochemically inserted Na in hard carbon electrode of sodium ion battery137140ENKazumaGotohToruIshikawaSaoriShimadzuNaoakiYabuuchiShinichiKomabaKazuyukiTakedaAtsushiGotoKenzoDeguchiShinobuOhkiKenjiroHashiTadashiShimizuHiroyukiIshidaThe state of sodium inserted in the hard carbon electrode of a sodium ion battery having practical cyclability was investigated using solid state 23Na NMR. The spectra of carbon samples charged (reduced) above 50 mAh g|1 showed clear three components. Two peaks at 9.9 ppm and 5.2 ppm were ascribed to reversible sodium stored between disordered graphene sheets in hard carbon because the shift of the peaks was invariable with changing strength of external magnetic field. One broad signal at about |9 to |16 ppm was assigned to sodium in heterogeneously distributed closed nanopores in hard carbon. Low temperature 23Na static and magic angle spinning NMR spectra didn't split or shift whereas the spectral pattern of 7Li NMR for lithium-inserted hard carbon changes depending on the temperature. This strongly suggests that the exchange of sodium atoms between different sites in hard carbon is slow. These studies show that sodium doesn't form quasi-metallic clusters in closed nanopores of hard carbon although sodium assembles at nanopores while the cell is electrochemically charged.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0008-6223792014In situ7Li nuclear magnetic resonance study of the relaxation effect in practical lithium ion batteries380387ENKazumaGotohMisatoIzukaJuichiAraiYumikaOkadaTeruyasuSugiyamaKazuyukiTakedaHiroyukiIshidaLithium ion cells comprising actual components of positive electrodes (LiCoO2, LiNixCoyAlz, and LiMn2O4) and negative electrodes (graphite and hard carbon) were assembled for in situ7Li nuclear magnetic resonance (NMR) experiments. The 7Li NMR measurements of the cells revealed a grelaxation effecth after overcharging: a decrease of the signal assigned to Li metal deposited on the negative electrode surface by overcharging. The reduction of the Li metal signal was inversely proportional to the increase of the signal of lithium stored in carbon. Therefore, the effect was ascribed to absorption of deposited lithium into the carbon of negative electrodes. The effect, which occurred rapidly in a few hours, reached an equilibrium state at 8–15 h. The slight shift of deposited metal suggests that dendritic Li easily re-dissolved, although larger Li particles remained. A hard carbon electrode has a greater effect of Li metal relaxation than graphite electrodes do, which is explainable by the bufferable structure of the carbon. Results are expected to be important for the discussion of the state of lithium, and for safer battery design.No potential conflict of interest relevant to this article was reported.ROYAL SOC CHEMISTRYActa Medica Okayama2050-74884342016Combination of solid state NMR and DFT calculation to elucidate the state of sodium in hard carbon electrodes 1318313193 ENRyoheiMoritaGraduate School of Natural Science & Technology, Okayama UniversityKazumaGotohGraduate School of Natural Science & Technology, Okayama UniversityMikaFukunishiElements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto UniversityKeiKubotaElements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto UniversityShinichiKomabaElements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto UniversityNaotoNishimuraDepartment of Chemistry and Materials Technology, Kyoto Institute of TechnologyTakashiYumuraDepartment of Chemistry and Materials Technology, Kyoto Institute of TechnologyKenzoDeguchiNational Institute for Materials ScienceShinobuOhkiNational Institute for Materials ScienceTadashiShimizueNational Institute for Materials ScienceHiroyukiIshidaGraduate School of Natural Science & Technology, Okayama UniversityWe examined the state of sodium electrochemically inserted in HC prepared at 700–2000 C using solid state Na magic angle spinning (MAS) NMR and multiple quantum (MQ) MAS NMR. The 23Na MAS NMR spectra of Na-inserted HC samples showed signals only in the range between +30 and |60 ppm. Each observed spectrum was ascribed to combinations of Na+ ions from the electrolyte, reversible ionic Na components, irreversible Na components assigned to solid electrolyte interphase (SEI) or non-extractable sodium ions in HC, and decomposed Na compounds such as Na2CO3. No quasi-metallic sodium component was observed to be dissimilar to the case of Li inserted in HC. MQMAS NMR implies that heat treatment of HC higher than 1600 C decreases defect sites in the carbon structure. To elucidate the difference in cluster formation between Na and Li in HC, the condensation mechanism and stability of Na and Li atoms on a carbon layer were also studied using DFT calculation. Na3 triangle clusters standing perpendicular to the carbon surface were obtained as a stable structure of Na, whereas Li2 linear and Li4 square clusters, all with Li atoms being attached directly to the surface, were estimated by optimization. Models of Na and Li storage in HC, based on the calculated cluster structures were proposed, which elucidate why the adequate heat treatment temperature of HC for high-capacity sodium storage is higher than the temperature for lithium storage.No potential conflict of interest relevant to this article was reported.INT UNION CRYSTALLOGRAPHYActa Medica Okayama2056-989075102019Crystal structures of 3-chloro-2-nitrobenzoic acid with quinoline derivatives: 3-chloro-2-nitrobenzoic acid-5-mtroqumohne (1/1), 3-chioro-2-nitrobenzoic acid-6-mtroquinoline (1/1) and 8-hydroxyquinolinium 3-chioro-2-nitrobenzoate15521557ENKazumaGotohDepartment of Chemistry, Faculty of Science, Okayama UniversityHiroyukiIshidaDepartment of Chemistry, Faculty of Science, Okayama University The structures of three compounds of 3-chloro-2-nitrobenzoic acid with 5-nitroquinoline, (I), 6-nitroquinoline, (II), and 8-hydroxyquinoline, (III), have been determined at 190 K. In each of the two isomeric compounds, (I) and (II), C7H4ClNO4 center dot C9H6N2O2, the acid and base molecules are held together by O - H center dot center dot center dot N and C - H center dot center dot center dot O hydrogen bonds. In compound (III), C9H8NO+center dot-C7H3ClNO4-, an acid-base interaction involving H-atom transfer occurs and the H atom is located at the N site of the base molecule. In the crystal of (I), the hydrogen-bonded acid-base units are linked by C -H center dot center dot center dot O hydrogen bonds, forming a tape structure along the b-axis direction. Adjacent tapes, which are related by a twofold rotation axis, are linked by a third C - H center dot center dot center dot O hydrogen bond, forming wide ribbons parallel to the ((1) over bar 03) plane. These ribbons are stacked via pi-pi interactions between the quinoline ring systems [centroid-centroid distances = 3.4935 (5)-3.7721 (6) angstrom], forming layers parallel to the ab plane. In the crystal of (II), the hydrogen-bonded acid-base units are also linked into a tape structure along the b-axis direction via C -H center dot center dot center dot O hydrogen bonds. Inversion-related tapes are linked by further C-H center dot center dot center dot O hydrogen bonds to form wide ribbons parallel to the ((3) over bar 08) plane. The ribbons are linked by weak pi-pi interactions [centroid-centroid distances = 3.8016 (8)-3.9247 (9) angstrom], forming a three-dimensional structure. In the crystal of (III), the cations and the anions are alternately linked via N - H center dot center dot center dot O and O - H center dot center dot center dot-O hydrogen bonds, forming a 2(1) helix running along the b-axis direction. The cations and the anions are further stacked alternately in columns along the a-axis direction via pi-pi interactions [centroid-centroid distances = 3.8016 (8)-3.9247 (9) angstrom], and the molecular chains are linked into layers parallel to the ab plane through these interactions.No potential conflict of interest relevant to this article was reported.International Union of CrystallographyActa Medica Okayama2056-9890752019Crystal structure of 4-chloro-2-nitrobenzoic acid with 4-hydroxyquinoline: a disordered structure over two states of 4-chloro-2-nitrobenzoic acid-quinolin-4(1H)-one (1/1) and 4-hydroxyquinolinium 4-chloro-2-nitrobenzoate1853ENKazumaGotohDepartment of Chemistry, Faculty of Science, Okayama UniversityHiroyukiIshidaDepartment of Chemistry, Faculty of Science, Okayama UniversityThe title compound, C9H7.5NO center dot C7H3.5ClNO4, was analysed as a disordered structure over two states, viz. co-crystal and salt, accompanied by a keto-enol tautomerization in the base molecule. The co-crystal is 4-chloro-2-nitrobenzoic acid-quinolin-4(1H)-one (1/1), C7H4ClNO4 center dot C9H7NO, and the salt is 4-hydroxy-quinolinium 4-chloro-2-nitrobenzoate, C9H8NO+center dot C7H3ClNO4. In the compound, the acid and base molecules are held together by a short hydrogen bond [O center dot center dot center dot O = 2.4393 (15) angstrom], in which the H atom is disordered over two positions with equal occupancies. In the crystal, the hydrogen-bonded acid-base units are linked by N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds, forming a tape structure along the a-axis direction. The tapes are stacked into a layer parallel to the ab plane via pi-pi interactions [centroid-centroid distances = 3.5504 (8)-3.9010 (11) angstrom]. The layers are further linked by another C-H center dot center dot center dot O hydrogen bond, forming a three-dimensional network. Hirshfeld surfaces for the title compound mapped over shape-index and d orm were generated to visualize the intermolecular interactions.No potential conflict of interest relevant to this article was reported.Royal Society of ChemistryActa Medica Okayama2050-74888292020Mechanisms for overcharging of carbon electrodes in lithium-ion/sodium-ion batteries analysed by operando solid-state NMR1447214481ENKazumaGotohGraduate School of Natural Science & Technology, Okayama UniversityTomuYamakamiGraduate School of Natural Science & Technology, Okayama UniversityIshinNishimuraGraduate School of Natural Science & Technology, Okayama UniversityHinaKometaniGraduate School of Natural Science & Technology, Okayama UniversityHidekaAndoGraduate School of Natural Science & Technology, Okayama UniversityKenjiroHashiNational Institute for Materials ScienceTadashiShimizuNational Institute for Materials ScienceHiroyukiIshidaGraduate School of Natural Science & Technology, Okayama UniversityA precise understanding of the mechanism for metal (Li and Na) plating on negative electrodes that occurs with overcharging is critical to managing the safety of lithium- and sodium-ion batteries. In this work, an in-depth investigation of the overlithiation/oversodiation and subsequent delithiation/desodiation of graphite and hard carbon electrodes in the first cycle was conducted using operando7Li/23Na solid-state NMR. In the 7Li NMR spectra of half cells of carbon electrodes and metal counter electrodes, three types of signals corresponding to Li dendrites that formed on the surface of graphite, hard carbon, and the counter electrode were distinguished from the signal of Li metal foil of the counter electrode by applying an appropriate orientation of the testing cell. For graphite overlithiation, the deposition of Li dendrites started immediately or soon after the minimum electric potential in the lithiation curve. In contrast, the deposition of Li dendrites in hard carbon started after the end of quasimetallic lithium formation for overlithiation at rates below 3.0C. Similar behaviour was also observed for the oversodiation of hard carbon. The formation of quasimetallic Li or Na in the pores of hard carbon serves as a buffer for the metal plating that occurs with overcharging of the batteries. Furthermore, some of the deposited Li/Na dendrites contribute to reversible capacities. A mechanism for the inhomogeneous disappearance of quasimetallic Li during delithiation of hard carbon is also proposed.No potential conflict of interest relevant to this article was reported.International Union of CrystallographyActa Medica Okayama2056-989076112020Crystal structures of four isomeric hydrogen-bonded co-crystals of 6-methylquinoline with 2-chloro-4-nitrobenzoic acid, 2-chloro-5-nitrobenzoic acid, 3-chloro-2-nitrobenzoic acid and 4-chloro-2-nitrobenzoic acid17011707ENKazumaGotohDepartment of Chemistry, Faculty of Science, Okayama UniversityHiroyukiIshidaDepartment of Chemistry, Faculty of Science, Okayama UniversityThe structures of the four isomeric compounds of 6-methylquinoline with chloro- and nitro-substituted benzoic acids, C7H4ClNO4·C10H9N, namely, 2-chloro-4-nitrobenzoic acid–6-methylquinoline (1/1), (I), 2-chloro-5-nitrobenzoic acid–6-methylquinoline (1/1), (II), 3-chloro-2-nitrobenzoic acid–6-methylquinoline (1/1), (III), and 4-chloro-2-nitrobenzoic acid–6-methylquinoline (1/1), (IV), have been determined at 185–190 K. In each compound, the acid and base molecules are linked by a short hydrogen bond between a carboxyl O atom and an N atom of the base. The O⋯N distances are 2.5452 (12), 2.6569 (13), 2.5640 (17) and 2.514 (2) Å, respectively, for compounds (I)–(IV). In the hydrogen-bonded acid–base units of (I), (III) and (IV), the H atoms are each disordered over two positions with O site:N site occupancies of 0.65 (3):0.35 (3), 0.59 (4):0.41 (4) and 0.48 (5):0.52 (5), respectively, for (I), (III) and (IV). The H atom in the hydrogen-bonded unit of (II) is located at the O-atom site. In all of the crystals of (I)–(IV), ฮ–ฮ interactions between the quinoline ring system and the benzene ring of the acid molecule are observed. In addition, a ฮ–ฮ interaction between the benzene rings of adjacent acid molecules and a C\H⋯O hydrogen bond are observed in the crystal of (I), and C\H⋯O hydrogen bonds and O⋯Cl contacts occur in the crystals of (III) and (IV). These intermolecular interactions connect the acid and base molecules, forming a layer structure parallel to the bc plane in (I), a column along the a-axis direction in (II), a layer parallel to the ab plane in (III) and a three-dimensional network in (IV). Hirshfeld surfaces for the title compounds mapped over dnorm and shape index were generated to visualize the weak intermolecular interactions.No potential conflict of interest relevant to this article was reported.