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[en] Batteries are a key technology in today’s society. They are used to power electric and hybrid electric vehicles and to store wind and solar energy in smart grids. 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 issues. To improve battery characteristics, deep insights into the structure of the materials during the battery reactions are necessary. Neutron Scatteringclarifies a wide range of structures for battery materials; from local to long range structures, and these structure characteristics are related to the battery properties. New materials with high electrochemical properties are necessary to improve future battery systems. Structure and property relationships for the battery electrodes and electrolytes are important information for designing new energy storage systems. An example of new materials is solid electrolytes. An all solid-state configuration is the most promising for future devices to improve the reliability of batteries. Lithium superionic conductors, which can be used as solid electrolytes, promise the potential to replace organic liquid electrolytes and thereby improve the safety of batteries. The material, Li10GeP2S12 shows high ionic conductivity, which exceeds the conductivity value of liquid electrolyte. Neutron Scatteringis one of the best methods to provide information of structure containing lithium and conduction mechanism determined by Neutron Scattering makes the materials design concept clear. In-situ and perando experimental techniques are another important subjects for clarifying battery reactions. An in situ technique for directly observing surface structural changes has been developed that employs thin-film model electrodes and surface X-ray and Neutron Scattering techniques. The surface structural changes commence with the formation of an electrical double layer, which is followed by surface reconstruction in the charge-discharge process. The structure information obtained by synchrotron X-ray diffraction and neutron reflectometry methods provides insight into the surface reaction, nano-effect of the electrode reaction, and degradation mechanism of battery reaction.
[en] The thallium ruthenate pyrochlores, Tl2Ru2O7-δ, were synthesized and their structures were determined by neutron diffraction measurements. The low-temperature (LT) and high-temperature (HT) phases were obtained at reaction temperatures of 500 and 900degC, respectively. Neutron diffraction measurements indicated the compositions of Tl2Ru2O7 and Tl2Ru2O6.71 for the HT phase and the LT phase, respectively. Electrical resistivity measurements showed metallic property for the HT phase and semiconducting property for the LT phase. The relationship between the electrical properties and the structural changes is discussed. (author)
[en] The copper-based polyanion compounds Li_6CuB_4O_1_0 and Li_2CuP_2O_7 were synthesized using a conventional solid-state reaction, and their electrochemical properties were determined. Li_6CuB_4O_1_0 showed reversible capacity of 340 mA g"−"1 at the first discharge–charge process, while Li_2CuP_2O_7 showed large irreversible capacity and thus low charge capacity. Ex situ X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) measurements revealed that the electrochemical Li"+ intercalation/deintercalation reaction in Li_6CuB_4O_1_0 occurred via reversible Cu"2"+/Cu"+ reduction/oxidation reaction. These differences in their discharge/charge mechanisms are discussed based on the strength of the Cu–O covalency via their inductive effects. - Graphical abstract: Electrochemical properties for Cu-based polyanion compounds were investigated. The electrochemical reaction mechanisms are strongly affected by their Cu–O covalentcy. - Highlights: • Electrochemical properties of Cu-based polyanion compounds were investigated. • The Li"+ intercalation/deintercalation reaction progressed in Li_6CuB_4O_1_0. • The electrochemical displacement reaction progressed in Li_2CuP_2O_7. • The strength of Cu–O covalency affects the reaction mechanism.
[en] The properties of a high ionic conductor Rb4Cu16I7+xCl13-x were studied by neutron and X-ray diffraction, and heat capacity measurements. The structure parameters of Rb4Cu16I7.2Cl12.8 were obtained by the Rietveld analysis of TOF neutron diffraction data between 50 and 300 K, which showed gradual excitation of migration of Cu ions from Cu(3) site into Cu(2) site with increasing temperature from about 100 K to room temperature. The heat capacity was measured between 10 and 300 K using a high precision adiabatic calorimeter. An abnormal increase was observed in the heat capacity curve above about 100 K. The excess heat capacity showed a broad anomaly with a maximum at about 190 K. The measurements were also made of Rb4Cu16I7Cl13 which showed slight different properties from Rb4Cu16I7.2Cl12.8. (author)
[en] The high temperature superconductors containing Cu metal have a wide range of oxygen nonstoichiometry, the degree of which strongly depends on the preparative conditions, especially on the oxygen partial pressure. The authors synthesized various superconductors under high oxygen pressure of 10-104 atm and studied the structural and electrical properties. The system they studied are as follows: (1) Ln1+XBa1-x Cu3Oy (Ln= Y, Gd, La) (2) YBa2 (Cu1-xMx)3Oy (M= Fe,Co,Ni,Zn) (3) YBaSrCu3Oy (4) Pb doped 105K class Bi-Sr-Ca-Cu-O system and others. In every case, many interesting phenomena were observed in the transition temperatures, structures and electrical properties
[en] New Li-Ti-N solid-solution compounds with an anti-fluorite-type superstructure were synthesized by heating the mixture of Li3N and TiN at 800degC in Ar flow. The compositions of the new compounds seem to lie on the tie-line between the two well-known compounds, Li3N (hexagonal, P6/mmm) and Li5TiN3 (cubic, I21/a-3) by Li evaporation during heating in Ar gas flow, and nominally represented with Li5+yTi1-yN3-y. The solubility is large; the anti-fluorite-type superstructure of Li5TiN3 (y=0) was retained up to y=ca. 0.9, which is close to the end member Li3N (y=1) with a different layered structure. This finding opens up further exploring other new Li-M-N (M=transition metals, group XIII, or XIV elements) phases with some attractive functions. (author)
[en] Solid solutions of LixNa1-xNiO2 were synthesized and their structures were determined by Rietveld analysis using TOF neutron diffraction data. Three phases were observed: monoclinic (C2/m) phase with x=0.00, rhombohedral(I) (R3-bar m) phase with 0.13 < x < 0.15, rhombohedral(II) (R3-bar m) phase with 0.70 < x < 1.00. Rietveld analysis of the rhombohedral(I) phase indicated no Ni disordering at the Li/Na (3a) site, and the disappearance of the cooperative Jahn-Teller ordering corresponds to the distances changes between the adjacent Ni layers. (author)
[en] A small/wide-angle neutron diffractometers (SWAN) covers very wide Q-range, 0.007A-1 to 12A-1, therefore this instrument is useful to investigate medium-range correlations in many materials, including biological materials. Two examples are here to show the usefulness of the wide Q-range measurements to understand Li-absorption mechanism in hard-carbon as a battery anode material and to investigate medium-range correlation in vapor deposited CCl4 glass system. (author)
[en] We report magnetic field (H) effect on the unconventional magnetism in LiNiO2 that consists of a spin-1/2 triangular (TRI) lattice through the 7Li nuclear spin lattice relaxation (1/T1) and NMR intensity measurements. Instead of a ferromagnetic (FM) ground state expected from the FM-Weiss constant, a marginal ordered state emerges below TM ∼ 20 K, evidenced from the wipe-out effect of 7Li-NMR signal and the divergent behavior of 1/T1 towards TM. The existence of the strong antiferromagnetic (AF) interaction along with the FM one is concluded to lead to a magnetically frustrated state at low temperatures and its AF exchange constant JAF is estimated to be about -20 K. This marginal ordered state due to the frustration of the antiferro-orbital order is found to be suppressed by applying H exceeding 10 T, revealing an orbital exchange constant J0 ∼ -10 K. In the paramagnetic regime at high temperatures, the system behaves like an assembly of local moments with an exchange frequency ωex ∼11 K, consistent with the energy scale of |J0| ∼ 10 K. The present experiments have revealed that |J0| ∼ 10 K is lower than spin exchange constants JFM ∼ 30 K, |JAF| ∼ 20 K. (author)