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Ionic Conductivity (ionic + conductivity)
Kinds of Ionic Conductivity Selected AbstractsSyntheses, Structures, Ionic Conductivities, and Magnetic Properties of Three New Transition-Metal Borophosphates Na5(H3O){M3II [B3O3(OH)] 3(PO4)6}×2H2O (MII: Mn, Co, Ni).CHEMINFORM, Issue 29 2006Miao Yang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Extremely High Silver Ionic Conductivity in Composites of Silver Halide (AgBr, AgI) and Mesoporous Alumina,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2006H. Yamada Abstract The silver ionic conductivity in heterogeneous systems of AgBr:Al2O3 and AgI:Al2O3 is highly enhanced by utilizing mesoporous Al2O3 as the insulating phase. The highest Ag+ conductivity of 3.1,×,10,3,,,1,cm,1 (at 25,°C) has been obtained for the AgI:Al2O3 composite with an Al2O3 volume fraction of 0.3. For AgBr:Al2O3, the enhancement of the conductivity is satisfactorily explained in the framework of the ideal space-charge model, while in the case of AgI:Al2O3 stacking disorder is also considered to contribute to the ionic conductivity. [source] ChemInform Abstract: Ionic Conductivity of Ce3NF6.CHEMINFORM, Issue 17 2010Gerd Noetzel Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Ionic Conductivity, Structure and Oxide Ion Migration Pathway in Fluorite-Based Bi8La10O27.CHEMINFORM, Issue 2 2010Yuandi Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Ag13I4(AsO4)3: Synthesis, Crystal Structure and Ionic Conductivity.CHEMINFORM, Issue 44 2009Dragan Pitzschke Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis, Crystal Structure and Ionic Conductivity of Ag8I2(CrO4)3.CHEMINFORM, Issue 32 2009Dragan Pitzschke Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Ag9I3(SeO4)2 (IO3)2 , Synthesis, Crystal Structure, and Ionic Conductivity.CHEMINFORM, Issue 49 2008Dragan Pitzschke Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Crystal Structure and Ionic Conductivity of a New Bismuth Tungstate, Bi3W2O10.5.CHEMINFORM, Issue 26 2006B. Muktha Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis and Structure of Na4/3Ce26/3(SiO4)6 (F1/3O2/3)2; Ionic Conductivity in the Apatite Series Na4/3Ln26/3(SiO4)6 (F1/3O2/3)2 (Ln: La, Ce, Gd) and Na4/3Ce26/3(SiO4)6O2.CHEMINFORM, Issue 11 2005V. Maisonneuve Abstract For Abstract see ChemInform Abstract in Full Text. [source] Sodium Trithiophosphate(V): Crystal Structure and Sodium Ionic Conductivity.CHEMINFORM, Issue 2 2004M. Pompetzki Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Dependence of Ionic Conductivity on Composition of Fast Ionic Conductors Li1+xTi2-xAlx(PO4)3, 0 , x , 0.7.CHEMINFORM, Issue 24 2002A Parallel NMR, Electric Impedance Study. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Preparation of Li4.4Al0.4Si0.6O4-xLi3BO3 Solid Electrolytes by Sol-Gel Method and Their Ionic ConductivityCHINESE JOURNAL OF CHEMISTRY, Issue 12 2002Hua-Ting Liu Abstract The Li4.4Al0.4Si0.6O4 -xLi3BO3 (x = 0 to 0.5) km conductors were prepared by the sol-gel method. The powder and sintered samples were characterized by DTA-TG, XBD, SEM and ac impedance techniques. The temperature of the preparation of powder patterns decreased by this method as compared to that of the preparation in solid state reaction. The conductivity and storability increased with Li3BO3, increasing from x = 0 to 0.2 in the Li4.4Al0.4S0.4O4-xLi3BO3, solid electrolytes. The particle size of the sintered pellets is about 0.12 ,m. The maximum conductivity at 20 °C is 3.165 × 10,5 S.cm,1 for Li4.4Al0.4Si0.6Q4 -0.2Li3BO3. [source] Ionic conductivity of solid polymer electrolytes for dye-sensitized solar cellsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Joo Wan Kim Abstract We developed an ionic conductivity model of solid polymer electrolytes for dye-sensitized solar cells (DSSCs) based on the Nernst,Einstein equation in which the diffusion coefficient is derived from the molecular thermodynamic model. We introduced concentration-dependence of the diffusion coefficient into the model, and the diffusion coefficient was expressed by differentiating the chemical potential by concentration. The ionic conductivities of polymer electrolytes (PEO/LiI/I2 system) were investigated at various temperatures and compositions. We prepared a set of PEO in which an EO : LiI mole ratio of 10 : 1 was kept constant for PEO·LiI·(I2)n compositions with n = 0.02, 0.05, 0.1, 0.15, 0.2, and 0.3 (mole ratio of LiI : I2). The ionic conductivities of the electrolytes were measured using a stainless steel/polymer-electrolyte/stainless steel sandwich-type electrode structure using alternating current impedance analysis. The values calculated using the proposed model agree well with experimental data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Ionic conductivity in poly (L-leucine)1,3-diamino propane,lithium iodide solid polymer electrolytePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2009N. H. Kaus Abstract The pelletized Poly(L-Leucine)-1,3-diamino propane,lithium iodide (LiI) samples have been prepared by using a low temperature sintering method. Results from impedance spectroscopy have proven this mixture to be a superionic material with maximum conductivity obtained in the range of 10,3,S/cm for the samples containing 50,wt% LiI. The high ionic conductivity achieved was due to the increased number of charge carrier from LiI. Improved conductivity could also be due to hopping of lithium ion through the side chain of polymer. Infrared spectroscopy showed that both LiI and poly amino acid may co-exist together. From the spectra it is revealed that the CO band at 1643,cm,1 shifted to higher wave number indicating that chelation of Li+ may have occurred at oxygen atom. Results from X-ray diffraction show that the prepared samples were partially crystalline in nature. Some of the peaks have disappeared and this confirmed that some complexation has occurred within the sample. Copyright © 2009 John Wiley & Sons, Ltd. [source] Polymers as functional components in batteries and fuel cells,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9-10 2006Gerhard Wegner Abstract The recent 10 years have seen an unprecedented development in the area of portable electronic devices: mobile phones, laptops, PDAS, and digital cameras have all become commodities on a large scale. All of these devices need a power supply in terms of a battery acceptable capacity, possibly rechargeable. This demand has triggered research and development in polymer materials science for lithium ion conducting polymers that could replace or avoid organic liquids as a supporting electrolyte. Moreover, polymers need to be optimized that act in the form of "gels" as framework and/or membrane materials to achieve mechanical integrity of the electrode compartments. Ionic conductivity for protons in polymeric systems is also the key issue in the development of so-called polyelectrolyte-membrane fuel cells (PEMFCs) that are supposed to work as power sources for mobile applications, e.g. in hybrid cars. A liquid fuel such as methanol would be converted to CO2 and H2O with concomitant production of electricity. Novel proton conducting polymer systems are required that work at temperatures between 150,200°C, that is under more or less water-free conditions. These requirements find an echo in the academic world in terms of renewed interest in the mechanisms of ionic transport phenomena in polymeric systems and in studies that aim for optimization of materials. In this article there will be a report on both lithium-ion and proton conducting polymers that have been recently developed in the authors' laboratory. The results will be discussed in the context of the demands that need to be met for advanced technologies. Copyright © 2006 John Wiley & Sons, Ltd. [source] Amorphous blends of poly(zwitterions) and zwitterionomers of the ammonioalkoxydicyanoethenolate type with some alkali metal saltsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2001Monique Galin Abstract Poly(zwitterions) and zwitterionomers of the ammonioethoxydicyanoethenolate type (functional dipolar unit R3N+,(CH2)2,O,CO,C,,(CN)2, µ,=,25.9 D) show the very specific property of solvation of some alkali metal salts to yield amorphous blends. For homopolymers in the (meth)acrylic series, solvation is observed up to a ratio r,=,[salt]/[zwitterion] of 1 for LiClO4 and NaSCN and of 0.5 for NaCF3SO3: it results in a significant plasticization (increasing order LiClO4,<,NaSCN,<,NaCF3SO3) and in the development in some cases of a poorly defined (lamellar?) local order, as evidenced by the presence of a single broad peak in the small-angle x-ray scattering (SAXS) patterns (Bragg distances of about 15,20 Ĺ). For the amorphous blend of a biphasic poly(tetramethyleneoxide) segmented zwitterionomer and NaCF3SO3 (r,=,0.5), selective solvation of the salt in the hard zwitterionic domains induces a transition from a lamellar structure (zwitterionic sublayer of about 9,Ĺ thickness) to an hexagonal packing of ionic-zwitterionic cylinders (radius of about 15 Ĺ). Ionic conductivity, measured in a narrow range of temperature just above the glass transition temperature, is characterized for most systems by an activation energy of about 1,1.8,eV; the drastic decrease of the conductivity by a factor of 103, when going from the homopolymer to the zwitterionomer blends, is typical of the inhibition of the ionic percolation process by the lack of connectivity of the ionic-zwitterionic domains. Copyright © 2001 John Wiley & Sons, Ltd. [source] Conductivity of Oriented Bis-azo Polymer FilmsCHEMPHYSCHEM, Issue 2 2006Dirk Apitz Abstract The conductivity properties of electro-optic, photoaddressable, dense bis-azo chromophore polymer films are investigated by using samples corona poled at various temperatures. A dielectric spectrometer is applied to measure the frequency dependence of the conductivity at different temperatures before and after heating the material to above the glass transition temperature. The results show that the orientation of the chromophores changes the charge-carrier mobility. Ionic conductivity dominates in a more disordered configuration of the material, while the competing process of hole hopping takes over as a transition to a liquid-crystalline phase occurs when the material is heated to much higher than the glass transition temperature. Such microcrystallization strongly enhances the conductivity. [source] Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized ZirconiaADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Michael Sillassen Abstract Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3 and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ,1 ,,1cm,1) are observed at 500,°C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions , one due to bulk conductivity and one attributable to conduction along the film,substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350,°C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150,500,°C are of great fundamental importance but may also be technologically relevant for low-temperature applications. [source] Silicon-Doped LiFePO4 Single Crystals: Growth, Conductivity Behavior, and DiffusivityADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Ruhul Amin Abstract Single crystals of silicon doped LiFePO4 with a silicon content of 1% are grown successfully by the floating zone technique and characterized by single-crystal and powder X-ray diffraction, secondary ion mass spectroscopy, and chemical analysis. Electron paramagnetic resonance demonstrates the presence of only Fe2+; no traces of Fe3+ are found. Impedance spectroscopy as well as step-function polarization/depolarization (DC) measurements are carried out using the cells Ti/LiFe(Si)PO4/Ti and LiAl/LiI/LiFe(Si)PO4/LiI/LiAl. The electronic and ionic conductivities as well as the Li-diffusivity of the sample in the major crystallographic directions ([h00], [0k0], and [00l]) are determined. Within experimental error the transport properties along the b- and c-axes are found to be the same but differ significantly from the a-axis, which exhibits lower values. Compared to undoped LiFePO4, Si-doping leads to an increase of the ionic conductivity while the electronic conductivity decreases, which is in agreement with a donor effect. The activation energies of conductivities and diffusivities are interpreted in terms of defect chemistry and relevant Brouwer diagrams are given. [source] Synthesis and characterization of poly(ethylene oxide- co -ethylene carbonate) macromonomers and their use in the preparation of crosslinked polymer electrolytesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2006Anette Munch Elmér Abstract Methacrylate-functionalized poly(ethylene oxide- co -ethylene carbonate) macromonomers were prepared in two steps by the anionic ring-opening polymerization of ethylene carbonate at 180 °C, with potassium methoxide as the initiator, followed by the reaction of the terminal hydroxyl groups of the polymers with methacryloyl chloride. The molecular weight of the polymer went through a maximum after approximately 45 min of polymerization, and the content of ethylene carbonate units in the polymer decreased with the reaction time. A polymer having a number-average molecular weight of 2650 g mol,1 and an ethylene carbonate content of 28 mol % was selected and used to prepare a macromonomer, which was subsequently polymerized by UV irradiation in the presence of different concentrations of lithium bis(trifluoromethanesulfonyl)imide salt. The resulting self-supportive crosslinked polymer electrolyte membranes reached ionic conductivities of 6.3 × 10,6 S cm,1 at 20 °C. The coordination of the lithium ions by both the ether and carbonate oxygens in the polymer structure was indicated by Fourier transform infrared spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2195,2205, 2006 [source] Aqueous Combustion Synthesis of Strontium-Doped Lanthanum Chromite CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Kishori Deshpande An aqueous combustion synthesis is used to produce powders of La0.8Sr0.2CrO3 perovskite. It is shown that interaction between chromium nitrate and glycine controls the process. In addition, it is suggested that glycine reacts with products of nitrate decomposition to yield an intermediate compound, which decomposes exothermically providing high-temperature conditions for complex oxide formation. It is remarkable that although reaction temperature is high (up to 800°C) and characteristic time is small (,1 s) for synthesis under the self-propagating high-temperature mode, the produced perovskites have high specific surface area (,40 m2/g) and well-defined crystalline structure. As a result, ceramics sintered by using these powders are dense (,96% of theoretical) and possess high electronic and low ionic conductivities, important for interconnect applications in solid oxide fuel cells. [source] Synthesis, Characterization and Ionic Conductive Properties of Phosphorylated Chitosan MembranesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 5-6 2003Ying Wan Abstract Phosphorylated chitosan membranes were prepared from the reaction of orthophosphoric acid and urea on the surface of chitosan membranes in N,N -dimethylformamide. Their ionic conductivity in the wet state was investigated. Chemical modifications contributed to improved ionic conductivities of the chitosan membranes. Compared to the unmodified chitosan membranes, it was found that hydrated phosphorylated chitosan membranes with an appropriate phosphorus content showed an increasing ionic conductivity of about one order of magnitude. The phosphorylation reaction mechanism was explained based on 13C and 31P NMR measurements. It was also observed that the crystallinity of the phosphorylated chitosan membranes and the corresponding swelling indices were changed pronouncedly, but these membranes did not lose either their tensile strength or thermal stability to a significant degree in comparison with the unmodified chitosan membranes. Possible reaction mechanism for preparation of phosphorylated chitosan membranes. [source] L'arséniate Na3Fe2(AsO4)3: étude structurale de la forme basse température et simulation des propriétés de conduction des cations alcalinsACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2008Najoua Ouerfelli The crystal structure of the low-temperature garnet-like form of trisodium diiron(III) triarsenate, Na3Fe2(AsO4)3, exhibits a three-dimensional framework with small tunnels running along the [111] direction, in which the Na+ cations are located. This study demonstrates the structural origins of the different ionic conductivities of the low- and high-temperature forms. Sodium conduction properties are simulated by means of the bond-valence-sum (BVS) model; the correlations between the low- and high-temperature crystal structures are discussed. The As, Fe and Na atoms lie on special positions (Wyckoff symbols 24d, 16a and 24c, respectively). [source] Anomalous Oxidation States in Multilayers for Fuel Cell ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010James M. Perkins Abstract Significant recent interest has been directed towards the relationship between interfaces and reports of enhanced ionic conductivity. To gain a greater understanding of the effects of hetero-interfaces on ionic conductivity, advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) are used to characterize CeO2/Ce0.85Sm0.15O2 multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and 18O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of the anomalous behavior of the Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed. [source] Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized ZirconiaADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Michael Sillassen Abstract Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3 and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ,1 ,,1cm,1) are observed at 500,°C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions , one due to bulk conductivity and one attributable to conduction along the film,substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350,°C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150,500,°C are of great fundamental importance but may also be technologically relevant for low-temperature applications. [source] Comparison between Nafion® and a Nafion® Zirconium Phosphate Nano-Composite in Fuel Cell ApplicationsFUEL CELLS, Issue 3-4 2006F. Bauer Abstract A comparative investigation of the electrical, mechanical, and chemical behaviour of zirconium phosphate-Nafion® composite membranes and Nafion® by means of ex-situ measurements, as well as with fuel cell operation, reveals a slight reduction of ionic conductivity, a significant improvement of mechanical stability, and increased water retention for the composite materials. The overall efficiency at 130,°C is increased during direct methanol fuel cell (DMFC) operation because the reduction in the ionic conductivity is overcompensated for by the decrease in methanol crossover. With H2 as the fuel, the slight reduction in overall efficiency corresponds to the decrease in ionic conductivity. The dimensional stability of the membrane and the membrane electrode assembly (MEA) is significantly improved for operating temperatures above 100,°C. A model for the microstructure-property relation for PFSA-Zr(HPO4)2,·,n,H2O composite membranes is presented, based on the experimental results from membranes with varying filler contents and distributions, obtained through different synthesis routes. It is aimed at the improvement of water distribution in the membrane upon fuel cell operation. [source] Silicon-Doped LiFePO4 Single Crystals: Growth, Conductivity Behavior, and DiffusivityADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Ruhul Amin Abstract Single crystals of silicon doped LiFePO4 with a silicon content of 1% are grown successfully by the floating zone technique and characterized by single-crystal and powder X-ray diffraction, secondary ion mass spectroscopy, and chemical analysis. Electron paramagnetic resonance demonstrates the presence of only Fe2+; no traces of Fe3+ are found. Impedance spectroscopy as well as step-function polarization/depolarization (DC) measurements are carried out using the cells Ti/LiFe(Si)PO4/Ti and LiAl/LiI/LiFe(Si)PO4/LiI/LiAl. The electronic and ionic conductivities as well as the Li-diffusivity of the sample in the major crystallographic directions ([h00], [0k0], and [00l]) are determined. Within experimental error the transport properties along the b- and c-axes are found to be the same but differ significantly from the a-axis, which exhibits lower values. Compared to undoped LiFePO4, Si-doping leads to an increase of the ionic conductivity while the electronic conductivity decreases, which is in agreement with a donor effect. The activation energies of conductivities and diffusivities are interpreted in terms of defect chemistry and relevant Brouwer diagrams are given. [source] Fabrication and Electrochemical Properties of Epitaxial Samarium-Doped Ceria Films on SrTiO3 -Buffered MgO SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Simone Sanna Abstract Thin films of samarium-oxide-doped (20,mol%) ceria (SDC) are grown by pulsed-laser deposition (PLD) on (001) MgO single-crystal substrates. SrTiO3 (STO) prepared by PLD is used as a buffer layer on the MgO substrates to enable epitaxial growth of the fluorite-structured SDC film; the STO layer provides a proper crystalline match between SDC and MgO, resulting in highly crystalline, epitaxial SDC films grown in the (001) orientation. Film conductivity is evaluated by electrochemical impedance spectroscopy measurements, which are performed at various temperatures (400,775,°C) in a wide range of oxygen partial pressure (pO2) values (10,25,1,atm) in order to separate ionic and electronic conductivity contributions. At 700,°C, SDC/STO films on (100) MgO exhibit a dominant ionic conductivity of about 7,×,10,2,S cm,1, down to pO2 values of about 10,15,atm. The absence of grain boundaries make the SDC/STO/MgO heterostructures stable to oxidation-reduction cycles at high temperatures, in contrast to that observed for the more disordered SDC/STO films, which degraded after hydrogen exposure. [source] Capacity Fading Mechanism in All Solid-State Lithium Polymer Secondary Batteries Using PEG-Borate/Aluminate Ester as Plasticizer for Polymer ElectrolytesADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Fuminari Kaneko Abstract Solid-state lithium polymer secondary batteries (LPB) are fabricated with a two-electrode-type cell construction of Li|solid-state polymer electrolyte (SPE)|LiFePO4. Plasticizers of poly(ethylene glycol) (PEG)-borate ester (B-PEG) or PEG-aluminate ester (Al-PEG) are added into lithium-conducting SPEs in order to enhance their ionic conductivity, and lithium bis-trifluoromethansulfonimide (LiTFSI) is used as the lithium salt. An improvement of the electrochemical properties is observed upon addition of the plasticizers at an operation temperature of 60,°C. However, a decrease of discharge capacities abruptly follows after tens of stable cycles. To understand the origin of the capacity fading, electrochemical impedance techniques, ex-situ NMR and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) techniques are adopted. Alternating current (AC) impedance measurements indicate that the decrease of capacity retention in the LPB is related to a severe increase of the interfacial resistance between the SPE and cathode. In addition, the bulk resistance of the SPE film is observed to accompany the capacity decay. Ex situ NMR studies combined with AC impedance measurements reveal a decrease of Li salt concentration in the SPE film after cycling. Ex situ SEM/EDS observations show an increase of concentration of anions on the electrode surface after cycling. Accordingly, the anions may decompose on the cathode surface, which leads to a reduction of the cycle life of the LPB. The present study suggests that a choice of Li salt and an increase of transference number is crucial for the realization of lithium polymer batteries. [source] Extremely High Silver Ionic Conductivity in Composites of Silver Halide (AgBr, AgI) and Mesoporous Alumina,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2006H. Yamada Abstract The silver ionic conductivity in heterogeneous systems of AgBr:Al2O3 and AgI:Al2O3 is highly enhanced by utilizing mesoporous Al2O3 as the insulating phase. The highest Ag+ conductivity of 3.1,×,10,3,,,1,cm,1 (at 25,°C) has been obtained for the AgI:Al2O3 composite with an Al2O3 volume fraction of 0.3. For AgBr:Al2O3, the enhancement of the conductivity is satisfactorily explained in the framework of the ideal space-charge model, while in the case of AgI:Al2O3 stacking disorder is also considered to contribute to the ionic conductivity. [source] | ||||||||||||||||||||||||||||