Superionic Conductor Glasses Research Articles

Diffusive dynamics in an amorphous superionic conductor

This work shows that ionic diffusion in a prototypic superionic-conducting glass proceeds via vacancies moving over a temporally stable network of ionic sites.

Novel Dynamics of Superionic Conducting Glasses Proved by Inelastic Neutron Scattering

The low-energy dynamics of Ag-based superionic conducting glass system has been investigated using the inelastic neutron scattering measurements. A clear correlation between the intensity in low-energy region and the dc ionic conductivity was found. The cross-linking factor is considered to be the network expansion by salt doping. Detailed investigations of low-energy dynamics both for varied superionic conducting glasses and insulator glass have proved that the peculiar Q dynamics beyond around 2 A -1 is a characteristic feature only in superionic conducting glass.

Rechargeable Ni-Li Battery Integrated Aqueous/Nonaqueous System

A rechargeable Ni-Li battery, in which nickel hydroxide serving as a cathode in an aqueous electrolyte and Li metal serving as an anode in an organic electrolyte were integrated by a superionic conductor glass ceramic film (LISICON), was proposed with the expectation to combine the advantages of both a Li-ion battery and Ni-MH battery. It has the potential for an ultrahigh theoretical energy density of 935 Wh/kg, twice that of a Li-ion battery (414 Wh/kg), based on the active material in electrodes. A prototype Ni-Li battery fabricated in the present work demonstrated a cell voltage of 3.47 V and a capacity of 264 mAh/g with good retention during 50 cycles of charge/discharge. This battery system with a hybrid electrolyte provides a new avenue for the best combination of electrode/electrolyte/electrode to fulfill the potential of high energy density as well as high power density.

A new type rechargeable lithium battery based on a Cu-cathode

In present work, we report a new type rechargeable lithium battery, in which a Cu-cathode in aqueous electrolyte and a Li-anode in non-aqueous electrolyte are united together by a lithium super-ionic conductor glass film (LISICON) through which only lithium-ions can pass. During the charge–discharge process, combining with the dissolution–deposition of metallic Cu (or Li) electrode, lithium ions transfer between aqueous electrolyte solution and non-aqueous electrolyte solution. In Li–Cu system, for the first time, the dissolution/deposition process of metallic Cu was used as cathode reaction to replace the Li-insertion/extraction reaction within conventional lithium-ion battery. The Cu-cathode is renewable, and displays a high capacity. The concept of Li–Cu system may provide a new direction for future lithium batteries study.

A lithium-air battery with a potential to continuously reduce O 2 from air for delivering energy

A lithium-air battery, in which the catalytic reduction of O 2 in an alkaline aqueous electrolyte and the metallic lithium in a non-aqueous electrolyte were subtly united together by a super-ionic conductor glass film (LISICON), was established in the present work. For this system, Mn 3O 4 based air diffusion electrode and metallic lithium were used as positive electrode and negative electrode, respectively. 500 h continuous discharge performance indicates that this kind of lithium-air battery has a potential to realize continuous reduction of O 2 from air to deliver energy like a fuel cell. During the long-time discharge process, the air electrode has delivered a special capacity of 50,000 mAh g −1 based on total mass of catalytic electrode (carbon + binder + catalyst). This result is much higher than that of previous studies about Lithium-air batteries.

CuI-Cu<sub>2</sub>MoO<sub>4</sub> 超イオン伝導性ガラスのナノ相分離

CuI-Cu<sub>2</sub>MoO<sub>4</sub> 超イオン伝導性ガラスのナノ相分離

Small angle neutron scattering experiments on solid electrolyte (AgI) x (AgPO3)1−x

Superionic conductor glasses have generated considerable technological interest in the applications such as batteries, fuel cell, sensors, etc. In AgPO3 glass doped by AgI, (AgI) x (AgPO3)1−x , small size of AgI clusters were formed and dispersed in the AgPO3 glass. The size of clusters in the sample depends on the AgI content and influences the electrical properties of the sample. To understand the microscopic structure, in particular the shape and size of the clusters, a series of small angle neutron scattering experiment on (AgI) x (AgPO3) x with x = 0.0, 0.5, and 0.7 were performed at the Neutron Scattering Laboratory–National Nuclear Energy Agency, Indonesia. By assuming the clusters are spherical, a radius of gyration R g of the clusters was determined from a Guinier plot. As there are different clusters sizes in the samples, a polydisperse model is also used to analyze the data. The results show that the average radius of clusters dispersed in (AgI) x (AgPO3)1−x samples with x = 0.0, 0.5, and 0.7 are around 236.2, 252.6, and 257.5 A, respectively.

Relation between High Ionic Conductivity and Low-energy Dynamics in Superionic Conducting Glass

The mechanism of high ionic conductivity in superionic conducting glass still constitutes an unsolved problem in the field of science. We performed the inelastic neutron scattering measurements of superionic glass system (AgI)x(Ag2S)x(AgPO3)1-2x using the chopper spectrometer at high flux neutron spallation source. The dynamical properties over the wide range momentum-energy space were precisely compared between superionic glass and insulator glass. We found that the superionic glass shows larger intensity in low-energy region compared with undoped insulator glass, and the increase of low-energy intensity is undoubtedly correlated with the dc ionic conductivity. We also found the peculiar Q dynamics of low-energy excitation in superionic glass indicating the in-phase dynamical correlations. These characteristic features in low-energy dynamics must provide the new insight on the mechanism of superionic glass.

Anion effect on the structure of Ag 2S–AgPO 3 superionic glasses

We report on time-of-flight neutron diffraction data measured on superionic-conducting glasses (Ag 2S) x (AgPO 3) 1− x with x=0.5 and 0.7 at room temperature via the High-Intensity Total Scattering (HIT-II) instrument at KENS and we contrast the results with AgPO 3, (AgI) 0.5(AgPO 3) 0.5 and (AgI) 0.33(Ag 2S) 0.33(AgPO 3) 0.34 glasses. The structure factor of (AgI) 0.5(AgPO 3) 0.5 shows a strong prepeak at low Q∼0.8 Å −1 in contrast to the undoped glass AgPO 3 where there is no prepeak. In the Ag 2S–AgPO 3 system the prepeak appears only very weakly and the difference between radial distribution function (RDF) of doped and undoped glasses show peaks at 2.15, 2.55, 2.75 and 3.0 Å, corresponding to PS, AgS, SS and SO distances, respectively. Both doped systems form superionic-conducting glasses, but the sulfide ion is largely incorporated into the phosphate tetrahedra, breaking down the corner-sharing chains into discrete PSO 3 tetrahedra.

Shallow‐ and deep‐luminescence centers in AgI‐based superionic conductor glass

The photoluminescence (PL), time-resolved photoluminescence (TRPL) and PL-excitation (PLE) spectra of superionic conductor glass (AgI)0.85(Ag2WO4)0.15 have been measured at different temperatures between 8 K and room temperature. The PL intensity peak is observed at 426 nm which corresponds to free exciton wavelength of pristine AgI. There are also different PL bands well related to the internal and interface states of mesoscopic AgI particles in Ag2WO4 glass matrix. This may give important information about the origins of superionic conduction. With increasing excitation light intensity, the PL efficiencies of several emission bands become saturated, except for the free exciton band.

Evidence of multisite exchange in AgI–AgPO 3 glasses: 109Ag NMR hole-burning spectra

A narrow 109Ag NMR spectrum of superionic conductor glass containing AgI exhibits strong broadening at low temperature or at low concentration of AgI. This broadening of the spectrum is attributed to the inhomogeneity of the local structure around Ag + ions in the glass. The temperature and composition dependence of the spectra can be well explained by a multisite exchange (MSE) model. The existence of the local inhomogeneity and the exchange of Ag + ions among them can be detected by site-selective hole-burning NMR technique. In this paper, the first measurement of the NMR hole-burning spectra of a superionic conductor glass of AgI–AgPO 3 is reported. A clear hole is observed below −20 °C, which diffuses to the higher-frequency region corresponding to AgI-rich sites, where the exchange rate is faster. This technique is very useful to investigate site exchange of ions in disordered systems.

Neutron scattering and thermal measurements on the superionic-conducting Ag 2S–AgPO 3 glass system

Superionic-conducting glasses (Ag 2S) x (AgPO 3) 1− x with x=0.1, 0.2, 0.3, 0.5, 0.7, 0.8 and 0.9 have been prepared by rapid quenching methods, although for x=0.8 and 0.9 they also contain crystalline Ag 2S. We report DTA measurements of the thermodynamic glass transition temperature, T g, and neutron diffraction data taken as a function of temperature through T g. The neutron measurements show no prepeak at any composition or temperature, indicating that there is no clustering, in contrast with the AgI–AgPO 3 system where clustering is found with a length scale of order 10 Å [1]. Both systems form superionic-conducting glasses, showing that clustering is not essential for such conductivity.

New organic–inorganic hybrid superionic conductor glasses consisting of silver iodide and alkylbis-trimethylammonium diiodides

New organic–inorganic hybrid superionic conductor glasses were developed, which consisted of silver iodide (AgI) and alkylbis-trimethylammonium diiodides. The glasses were prepared from low-temperature molten salts of them by melt quenching method, which were confirmed in glassy state by X-ray diffraction (XRD), DSC and optical microscope observation. The ionic conductivity of these glasses are about 10 −2 Ω −1 cm −1 at room temperature which is the best in the organic–inorganic hybrid superionic conductor glasses obtained so far. Ag-109 NMR spectra of the glasses showed a motionally narrowed peak at about 800 ppm regardless of their compositions, which is almost equal to the value of AgI crystals. These results are in good agreement with the prediction of the percolation model, where the silver cations are assumed to diffuse through the conduction channels of face-sharing iodide tetrahedra, which are randomly blocked by organic substances.

XPS Study of Surface Properties in the Superionic Conducting Glass Of (AgI)0.4(Ag2O)0.3(MoO3)0.3 Bombarded by Ion and Electron Beams

Article XPS Study of Surface Properties in the Superionic Conducting Glass Of (AgI)0.4(Ag2O)0.3(MoO3)0.3 Bombarded by Ion and Electron Beams was published on March 1, 2001 in the journal High Temperature Materials and Processes (volume 20, issue 1).

Structure and ionic conductivity of rapidly quenched AgI–Ag 2WO 4 superionic conductor glasses

Silver ion conducting glasses composed of (AgI) x –(Ag 2WO 4) 1− x ( x=0.80–0.55) were prepared by a rapid melt quenching method. Their physical properties were investigated by X-ray, DSC, impedance and Ag-109 NMR measurements. The glass transition temperatures were in the range from 110°C to 187°C. The glasses show unusually high ionic conductivities of 2.5 × 10 −3 S/cm at x=0.55 and 2.3 × 10 −1 S/cm at x=0.80, which varied exponentially with increasing AgI content. Ag-109 NMR spectra also support the high mobility of silver ions in the glasses. Structures of the glasses were investigated by FTIR and W-L 1 edge XANES. From these results it is concluded that the tungsten ions are octahedrally coordinated by oxygen ions as in crystalline Ag 2WO 4 and Ag 26I 18W 4O 16, which is quite different from the structure of AgI–Ag 2MoO 4 glasses.

Local Environmental Structures of Mo in the Superionic Conducting Glass (AgI)0.6(Ag2MoO4)0.4 by Anomalous X-ray Scattering

The anomalous X-ray scattering (AXS) method using Mo K absorption edges has been employed for obtaining the local structural information of superionic conducting glass having the composition (AgI)(0.6)(Ag2MoO4)(0.4). The possible atomic arrangements in the near-neighbor region of this glass were estimated by coupling the results with the least-squares variational analysis so as to reproduce the differential intensity profile for Mo as well as the ordinary scattering profile. The coordination number of oxygen around Mo is found to be about 4 at the distance of 0.180 mn. This implies that the most probable structural entity in the glass is the MoO4 tetrahedral unit which has been proposed based on infrared spectroscopy. The value of the coordination number of I- around Ag+ is estimated as 4.4 at 0.287 nm, suggesting an arrangement similar to that of crystalline or molten AgI.

Frequency dependent conductivity of organic–inorganic mixed superionic conductor glasses

In order to detect local motion of mobile silver cations in organic–inorganic mixed glasses composed of AgI and alkylammonium iodides, their electrical conductivity at radio and microwave frequencies was measured in different compositions. Although their DC conductivity shows a clear transition from insulator to superionic conductor at AgI volume fraction φ∼0.35, the high frequency value is continuous at the threshold. Details of frequency dependence were measured at room temperatures from DC to 10 GHz. Only a small dependence was seen in the high conducting glasses, however, the sample near the percolation threshold showed power-law dependence σ[ ω]∼ ω n at low frequency whose slope n∼0.6 and approaches to unity at high frequencies.

XPS Study of the Effect of Ar-Ion Bombardment and Aging on Surface Properties of Superionic Conducting Glass (CuI)<SUB>0.3</SUB>(Cu<SUB>2</SUB>O)<SUB>0.35</SUB>(MoO<SUB>3</SUB>)<SUB>0.35</SUB>

XPS analysis has been used for characterizing the effects of argon-ion bombardment and aging at room temperature on the surface properties of the superionic conducting glass having the composition (CuI) 0.3 (Cu 2 O) 0.35 (MoO 3 ) 0.35 . Copper and molybdenum ions in this particular glass are found to be significantly reduced by argon-ion bombardment, Cu 2+ to Cu 0 and Mo 6+ to Mo 4+ . The chemical change is attributed to preferential sputtering of iodine and oxygen from the surface of the glass. The concentration of copper on the surface increases and that of molybdenum decreases with aging at room temperature. From aging curves, the diffusion coefficient of copper is estimated to be of the order of 10 -23 m 2 .s -1 .

Photo-electrochemical properties of multi-layered thin films composed of chalcogenide and superionic conductor glasses

Multi-layered thin films, which consisted of metallic silver, GeSe 3 glass, and silver oxyhalide superionic conductor glass were prepared. Photo- and electrochemical reaction of metallic silver with the chalcogenide glass layer was studied by optical absorbance and cyclic-voltammetry. Photo-doping of silver through the superionic glass layer was observed using evaporated AgIAg 2MoO 4 film and it was partly undoped by electrochemical treatment. However, no photo-doping was observed for the cell consisting of a AgIAgPO 3 dip-coated layer. The doped silver was dissolved into the GeSe 3 layer during the photo-doping process. However, it formed another intermediate compound layer (probably silver selenide) during the electrodoping process.

Intermediate range structure of organic-inorganic mixed superionic conductor glasses: AgI and tetraalkylammonium iodides

Intermediate range structures of organic-inorganic mixed superionic conductor glasses were investigated by low-angle neutron diffraction and small-angle neutron scattering (SANS) experiments. Significant small angle scatterings were observed in the glasses composed of AgI-CsI-deuterized-tetramethylammonium iodides. The fractal dimension D f was estimated from the plot of the log I(q) vs. Log q; it was 0.39 above q c and 2.8 below, where q c was a cross-over wavelength of q c ∼ 0.02−0.05 A ̊ − 1 . This result strongly supports the existence of percolation clusters in the organic-inorganic mixed superionic conductor glasses, which has been expected from ionic conductivity measurements.