Nobuya Machida

All-Solid-State Lithium Battery with LiCo0.3Ni0.7 O 2 Fine Powder as Cathode Materials with an Amorphous Sulfide Electrolyte

An all-solid-state battery was fabricated with LiCo 0.3 Ni 0.7 O 2 fine powder as cathode materials. The LiCo 0.3 Ni 0.7 O 2 fine powder was synthesized with oxalate decomposition methods and the average particle size of the powder was 2 μm diam. In the all-solid-state battery, a-60Li 2 S.40SiS 2 powder, which was prepared by a mechanical milling process, was used as the solid electrolyte. The anode was metallic indium foil 0.127 mm thick. The charge-discharge cycling test of the battery was carried out under a constant current density of 64 μA cm -2 with a 3.8 and 2.0 V charge-discharge criteria. The battery showed a rechargeable specific capacity of 98 mAh g -1 based on the cathode materials. The charge-discharge cycle efficiency of the battery was almost unity after the second cycle.

FT-IR, FT-Raman and 95Mo MAS–NMR studies on the structure of ionically conducting glasses in the system AgI–Ag2O–MoO3

Local environments of molybdenum in glasses of the system (AgI)y–[(Ag2O)x–(MoO3)1−x]1−y were investigated by use of near-infrared Fourier transform (NIR-FT) Raman spectroscopy, FT-IR spectroscopy, and 95Mo magic-angle spinning (MAS) NMR. Specifically, the following cross-sections of the composition diagram were studied: series I: x=0.5, and 0.50≤y≤0.75 and series II: y=0.50, and 0.4≤x≤0.5. Comparison of the spectroscopic results with those obtained on crystalline model compounds indicates that the structures of series I- glasses (composition ratio Ag2O/MoO3=1) are solely based on Ag+, I−, and isolated MoO42− anions. On the other hand, glasses of series II (composition ratio Ag2O/MoO3<1) have a more complex structure consisting of both tetrahedral orthomolybdate, MoO42−, and a second, polynuclear species, in which MoO6 octahedra are linked to MoO4 tetrahedra in a manner similar to the structure of crystalline Na2Mo2O7.

Preparation of cuprous ion-conducting glasses in the system CuICu2OMoO3

Abstract The glass formation was tried in the systems CuICu 2 OM m O n , where M m O n is B 2 O 3 , V 2 O 5 , MoO 3 or WO 3 . The glasses, however, were only obtained in the CuICu 2 OMoO 3 system. The glass-forming region was mainly found in pseudobinary system CuICu 2 MoO 4 , similar to glasses in the system AgIAg 2 OMoO 3 . Glass transition temperatures range from 125 to 150°C and do not change so much with CuI content while they increase with an increase in MoO 3 content. The IR spectra showed that the pseudobinary glasses were only composed of Cu + , I − and monomer MoO 4 2− ions, and classified as “ionic” glasses containing one type of cations. The molar volume of the glasses in the pseudobinary system was primarily determined by a fairly dense packing of the constituent anions, I − and MoO 4 2− .

Ionic conductivity of rapidly quenched glasses with high concentration of lithium ions

Glasses were prepared over a wide range of compositions in the systems Li 2 O-SiO 2 -B 2 O 3 , Li 2 O-B 2 O 3 -P 2 O 5 , and Li 2 O-P 2 O 5 -SiO 2 using a rapid quenching technique. The widest glass-forming region was observed in the system Li 2 O-SiO 2 -B 2 O 3 . The conductivities of these rapidly quenched glasses were measured; the composition dependence of conductivity was found to be closely related to that of Tg. The enhancement of conductivity by the mixing of two glass-forming oxides, which can be called the mixed-anion effect, was observed in the Li 2 O-SiO 2 -B 2 O 3 glasses containing large amounts of Li 2 O. The cause of this enhancement was discussed on the basis of the variations of the conductivity, T g , and (T 1 − T g )/T 1 as a function of the Li 2 O content.

Behavior of rapidly quenched V/sub 2/O/sub 5/ glass at cathode in lithium cells

A vanadium oxide glass has been prepared by a rapid quenching technique, and the electrochemical lithium insertion into the Li/sub 2x/V/sub 2/O/sub 5/ glass is investigated. The open-circuit voltage (OCV) of the lithium cell with the Li/sub 2x/V/sub 2/O/sub 5/ glass gradually is decreased with increasing the stoichiometric parameter x, while OcV of crystalline Li/sub 2x/V/sub 2/O/sub 5/ has three voltage plateaus. This difference suggests that a homogeneous single phase exists in the glass all over the insertion range. The chemical diffusion coefficients in the glass are higher by 1-2 orders of magnitude than those of the polycrystalline {Beta}-Li/sub 2x/V/sub 2/O/sub 5/.

STRUCTURE AND ELECTRICAL PROPERTIES OF CU+ ION-CONDUCTING OXYHALIDE GLASSES IN THE SYSTEM CUI-CUPO3-CU2MOO4

Abstract Cu + ion-conducting glasses were prepared in the pseudoternary system CuI—CuPO 3 —Cu 2 MoO 4 . Infrared spectra of the glasses with a constant CuI content suggested that non-bridging oxygens were more preferentially formed in the phosphate groups than in the molybdate groups. This preference order for non-bridging oxygen formation was consistent with the order of acidity, P 2 O 5 >MoO 3 , of the glass-forming oxides in melts. These glasses showed high ionic conductivities of 10 -2 to 10°Sm -1 at room temperature. For the glasses with a constant CuI content, the conductivity at 298 K of the glasses decreased non-linearly with an increase in the composition parameter x , which denotes the ratio of the number of phosphorus atoms to the total number of phosphorus and molybdenum atoms included in the glasses, x =[ rmP ]/([ rmP ] +[ rmMo ]). The activation energy for conduction inceased non-linearly with an increase in x . These non-linear changes in the conductivity and in the activation energy were correlated with the structural change during melting of these glasses.

Preparation of new glasses with high ionic conductivities

Abstract Glasses have long been known commonly as electric “insulators”. Recently, however, the ionic conductivities are shown to be higher in glasses than in the corresponding crystals. This is probably due to the fact that the glasses are made through quenching the melts and thus the glasses maintain to some extent the structure and properties of the melts. In the context mentioned above, we propose several principles to search for and develop new glasses with high ionic conductivities; incorporation into glasses of compounds which exhibit (a) high conductivity in the melts and (b) a small conductivity difference at the freezing point (melting point) of the compounds. The glasses containing compounds fulfilling these two conditions may have high ionic conductivities with condition (b) seeming to be most important, as well as the ionic radius and the electronic configuration of the mobile ions.

Electrochromic properties of sputtered amorphous films in the systems WO/sub 3/-Nb/sub 2/O/sub 5/ and Li/sub 2/O-WO/sub 3/-Nb/sub 2/O/sub 5/

Electrochromic behavior has been studied by potentiostatic and galvanostatic measurements on sputtered amorphous films in the systems Li/sub 2/O-WO/sub 3/Nb/sub 2/O/sub 5/ and WO/sub 3/-Nb/sub 2/O/sub 5/. The bleaching of films containing Li/sub 2/O was complete, whereas the films without Li/sub 2/O showed a residual color. The kinetics of bleaching in the Li/sub 2/O-WO/sub 3/-Nb/sub 2/O/sub 5/ films was ascribed to a space-charge-limited current flow, while that of WO/sub 3/-Nb/sub 2/O/sub 5/ films could not be explained by a space-charge-limited current model. Such a difference in electrochromic properties is caused by the addition of Li/sub 2/O, which increases the conductivity of Li/sup +/ ions in the films.

Electrochemical insertion of lithium ions into V2O5 glasses containing transition-metal oxides

Abstract Vanadium oxide glasses containing transition-metal oxides M m O n were prepared by rapid quenching, and the electrochemical insertion of lithium ions into these glasses was investigated. The lithium cells with these glasses showed high open-circuit voltages (OCV) of over 3.0 V, and OCV of the cells were found to decrease with an increase in the stoichiometric parameter x =Li/(M+V). The chemical diffusion coefficients of the glass containing Fe 2 O 3 were higher by 1–2 orders of magnitude than those of pure V 2 O 5 glass.

Cyclic voltammetric study on vanadium oxide based glasses as cathode in rechargeable lithium batteries

Abstract The V 2 O 5 glasses containing a transition-metal oxide, Fe 2 O 3 of CuO, were prepared by rapid quenching and their electrochemical behavior as cathode in the lithium cells was investigated. The cyclic voltammetric study which was carried out in the voltage range from 2.0 to 4.0 V against the lithium electrode indicated that the glass 20Fe 2 O 3 ·80V 2 O 5 had a complete reversibility for lithium intercalation-deintercalation reactions. The cyclic voltammograms of the glass 33.3CuO·66.7V 2 O 5 and of the pure V 2 O 5 glass indicated a lack of complete reversibility for intercalation-deintercalation reactions. The lithium cell with the glass 20Fe 2 O 3 ·80V 2 O 5 showed the high specific capacity of about 140 Ah kg -1 , when the discharge-charge cycle was carried out under a constant current density of 5.4 Am -2 .