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Advances in solid-state batteries have primarily been driven by the discovery of superionic conducting structural frameworks that function as solid electrolytes. We demonstrate the ability of high-entropy metal cation mixes to improve ionic conductivity in a compound, which leads to less reliance on specific chemistries and enhanced synthesizability. The local distortions introduced into high-entropy materials give rise to an overlapping distribution of site energies for the alkali ions so that they can percolate with low activation energy. Experiments verify that high entropy leads to orders-of-magnitude higher ionic conductivities in lithium (Li)-sodium (Na) superionic conductor (Li-NASICON), sodium NASICON (Na-NASICON), and Li-garnet structures, even at fixed alkali content. We provide insight into selecting the optimal distortion and designing high-entropy superionic conductors across the vast compositional space. [ABSTRACT FROM AUTHOR]

Abstract In this study, the dielectric properties of the liquid crystal 4–(7,7,8,8,9,9,10,10,10–nonafluorodecyloxy)biphenyl–4′–carboxylic acid (NBCA) exhibiting a Smectic C mesophase have been analyzed. NBCA has two critical temperatures which are 194 °C for the crystal phase to the smectic phase transition, and 269 °C for the smectic phase to the isotropic phase transition. Impedance spectroscopy measurements were made at regular intervals at different temperatures which includes these transitions. By using capacitance method, the complex dielectric constants have been calculated for each temperature, and the real part of dielectric constants have been fitted to the Cole-Cole equation. In addition, ac conductivity mechanisms of the NBCA at different temperatures and different phases and also activation energies which belongs to some selected frequencies have been determined by the imaginary part of dielectric constants. Highlights • The dielectric properties of the liquid crystal NBCA have been analyzed. • The transition temperatures were verified by dielectric measurements of the NBCA. • The conductivity mechanisms for different temperatures have been determined. • The activation energies for selected angular frequencies have also been calculated. • This characterization of NBCA can be beneficial for liquid crystal applications. [ABSTRACT FROM AUTHOR]

Progress in energy‐related technologies demands new and improved materials with high ionic conductivities. Na‐ and Li‐based compounds have high priority in this regard owing to their importance for batteries. This work presents a high‐throughput exploration of the chemical space for such compounds. The results suggest that there are significantly fewer Na‐based conductors with low migration energies as compared to Li‐based ones. This is traced to the fact that, in contrast to Li, the low diffusion barriers hinge on unusual values of some structural properties. Crystal structures are characterized through descriptors derived from bond‐valence theory, graph percolation and geometric analysis. A machine‐learning analysis reveals that the ion migration energy is mainly determined by the global bottleneck for ion migration, by the coordination number of the cation and by the volume fraction of the mobile species. This workflow has been implemented in the open‐source Crystallographic Fortran Modules Library (CrysFML) and the program BondStr. A ranking of Li‐ and Na‐based ionic compounds with low migration energies is provided. This work reports a high‐throughput screening of Li and Na compounds. Bond‐valence theory, graph percolation and geometric analysis are combined to investigate the structural properties of fast ion conductors. The results suggest that the abundance of fast ion conductors would be substantially lower in the Na case. [ABSTRACT FROM AUTHOR]

Abstract In this work, maximum power density as the function of electrolyte thickness of a solid oxide fuel cell (SOFC) with Ce 0.9 Gd 0.1 O 2-δ (GDC10) electrolyte was calculated by integrating partial conductivities of charge carriers under various DC bias conditions at a fixed oxygen chemical potential gradient at both sides of the electrolyte. Partial conductivities as a function of temperature and oxygen partial pressure (P O 2) were calculated using Hebb-Wagner polarization method and spatial distribution of P O 2 across the electrolyte was calculated based on Choudhury and Patterson's model [1] by considering reversible electrode conditions. At terminal voltages corresponding to SOFC and electrolysis cell operation modes, the oxygen chemical potential gradient at a electronic-stoichiometric point became maximum and minimum to compensate the contribution from electrochemical potential gradient of electron. The current-voltage characteristics in different fuel cell conditions with temperature and thickness dependence were calculated with cathodic and anodic P O 2 of 0.21 and 10−22 atm, respectively. The theoretical maximum power density increased from 1.26 W·cm−2 at 500 °C to 7.39 W·cm−2 at 700 °C. Similarly, at 500 °C, power density increased two fold on reducing electrolyte thickness from 20 μm to 10 μm. The implications of these results on the development of GDC10 based SOFC systems was discussed. Highlights • Spatial distribution of P O 2 across GDC10 under various DC bias was calculated. • Hebb-Wagner polarization method was used to calculate partial conductivities. • Max. theoretical power density w.r.t. temperature and thickness were calculated. [ABSTRACT FROM AUTHOR]

Abstract: Samples of (TlGaSe2)1 - x(TlInS2)x solid solutions are synthesized. The frequency dependences (2 × 101-106 Hz) of components of the total complex impedance are studied by the impedance spectroscopy technique and relaxation processes are investigated depending on the composition of the (TlGaSe2)1 - x(TlInS2)x solid solution in the solubility region (x = 0-0.4). Corresponding diagrams on the (Z''-Z') complex plane are analyzed using the equivalent substitutional circuit method. An anomaly in the temperature dependence of the electrical conductivity, which manifests itself in an abrupt increase in the conductivity, is found for the studied (TlGaSe2)1 - x(TlInS2)x solid solution at 400 K. This peculiarity is associated with the phase transition into the superionic state. [ABSTRACT FROM AUTHOR]

This work shows the contribution of both ionic and electronic conductivities in chitosan (CS) based solid polymer electrolytes incorporated with various amounts of copper nitrate (CuNt). The samples were prepared using solution cast technique. The second semicircles at intermediate frequency in impedance plots were observed. Surface plasmonic resonance (SPR) was illustrated from the UV-Vis spectrophotometry, where broad peaks at 702 nm were obtained as an evidence for nanoparticles formation. The second semicircles in the impedance plots and the distinguished SPR peaks have revealed the contribution of electronic conductivity in CS:CuNt based polymer electrolytes. The same trend of UV-Vis spectra at different temperatures reveals that CS:CuNt polymer electrolyte is thermally stable. The presence of electronic conductivity is the main shortcoming of copper ion conducting solid polymer electrolytes. The role of lattice energy of the copper salts on electrical properties and morphological (SEM) appearance was discussed. The TEM image shows Cu nanopartciles with various sizes. A stable SPR peak and vanishing of second semicircle at high temperatures reveals the stability of copper ion conducting chitosan based polymer electrolytes. The pattern of DC conductivity and dielectric constant as a function of salt concentration are almost found to be similar. Both estimated DC conductivities from AC spectra and those calculated from impedance plots are shown to be comparable. Highest DC conductivity of 3.65 × 10−5 S/cm has been achieved for the sample incorporated with 21 wt% of CuNt. The high value of dielectric constant at low frequency can be ascribed to electrode polarization. Electric modulus parameters are studied to understand the relaxation process. Two semicircles in Argand plots were separated. [ABSTRACT FROM AUTHOR]

Materials in the Na-rich antiperovskite family are promising candidates as solid electrolytes (SEs) for all-solid-state Na-ion batteries (NIBs). In this work, we carry out ab-initio calculations to study various properties of Na 3 OCl , namely the formation energies of various neutral defect pairs, the defect hopping barriers, the solution energies of high valence alkali earth metal substitutes to the Na atoms, and the effect of such substitution to the Na migration. While the introduction of alkali earth metal ions increases the Na vacancy concentration, the activation energy of Na transport also increases. Furthermore, we identify Ca as the most promising alkali earth metal to be doped into Na 3 OCl due to its low binding energy and relatively small impact on the migration barrier. Our work provides a theoretical framework for further improving the Na conductivity of materials in the antiperovskite family for all-solid-state NIBs. [ABSTRACT FROM AUTHOR]

Despite its critical role in determining the performance of lithium ion batteries (LIBs), evolution of the chemical composition and morphology of the solid electrolyte interphase (SEI) formed on graphite negative electrodes remains poorly described even for a conventional electrolyte consisting of 1 M LiPF 6 dissolved in a mixture of ethylene carbonate (EC)/dimethyl carbonate (DMC), which is considered here. The EC − radical anion produced from one-electron reduction of EC is known to be a key intermediate responsible for the formation of two commonly found products in the SEI, carbonate (CO 3 2− ) and ethylene dicarbonate (EDC 2− ). We evaluate the diffusion behavior of EC − associated with solvent reorganization near the graphite electrode using molecular dynamics (MD) and metadynamics simulations. The predicted free energy profiles of EC − transport at the onset of SEI formation show two distinct minima, depending on the EC:DMC ratio of the solvent and the voltage applied to the electrode. EC − radical intermediates trapped in the free energy well located at z  = 0.65 nm (or z  = 1.5 nm) from the electrode surface may favorably undergo further reduction to CO 3 2− (or a combination reaction with another EC − to form EDC 2− ). Moreover, suppressed EC − migration could contribute to the formation of a thin, compact SEI layer. This study highlights that in addition to the kinetics and thermodynamics of solvent reduction, the near-electrode transport of reaction intermediates/products should be considered in modeling of SEI structure and growth. [ABSTRACT FROM AUTHOR]

Benefiting from extremely high shear modulus and high ionic transference number, solid electrolytes are promising candidates to address both the dendrite-growth and electrolyte-consumption problems inherent to the widely adopted liquid-phase electrolyte batteries. However, solid electrolyte/electrode interfaces present high resistance and complicated morphology, hampering the development of solid-state battery systems, while requiring advanced analysis for rational improvement. Here, we employ an ultrasensitive three-dimensional (3D) chemical analysis to uncover the dynamic formation of interphases at the solid electrolyte/electrode interface. While the formation of interphases widens the electrochemical window, their electronic and ionic conductivities determine the electrochemical performance and have a large influence on dendrite growth. Our results suggest that, contrary to the general understanding, highly stable solid electrolytes with metal anodes in fact promote fast dendritic formation, as a result of less Li consumption and much larger curvature of dendrite tips that leads to an enhanced electric driving force. Detailed thermodynamic analysis shows an interphase with low electronic conductivity, high ionic conductivity, and chemical stability, yet having a dynamic thickness and uniform coverage is needed to prevent dendrite growth. This work provides a paradigm for interphase design to address the dendrite challenge, paving the way for the development of robust, fully operational solid-state batteries. [ABSTRACT FROM AUTHOR]

The salt compounds NaB11H14, Na-7-CB10H13, Li-7-CB10H13, Na-7,8-C2B9H12, and Na-7,9-C2B9H12 all contain geometrically similar, monocharged, nido-undeca(carba)borate anions (i.e., truncated icosohedral-shaped clusters constructed of only 11 instead of 12 {B-H} + {C-H} vertices and an additional number of compensating bridging and/or terminal H atoms). We used first-principles calculations, X-ray powder diffraction, differential scanning calorimetry, neutron vibrational spectroscopy, neutron elastic-scattering fixed-window scans, quasielastic neutron scattering, and electrochemical impedance measurements to investigate their structures, bonding potentials, phase-transition behaviors, anion orientational mobilities, and ionic conductivities compared to those of their closo-poly(carba)borate cousins. All exhibited order-disorder phase transitions somewhere between room temperature and 375 K. All disordered phases appear to possess highly reorientationally mobile anions (> ~1010 jumps s-1 above 300 K) and cation-vacancy-rich, close-packed or body-center-cubic-packed structures [like previously investigated closo-poly(carba)borates]. Moreover, all disordered phases display superionic conductivities but with generally somewhat lower values compared to those for the related sodium and lithium salts with similar monocharged 1-CB9H10- and CB11H12- closo-carbaborate anions. This study significantly expands the known toolkit of solid-state, poly(carba)borate-based salts capable of superionic conductivities and provides valuable insights into the effect of crystal lattice, unit cell volume, number of carbon atoms incorporated into the anion, and charge polarization on ionic conductivity. [ABSTRACT FROM AUTHOR]

A new composite solid electrolyte was synthesized by a mixture of Li 2 S, P 2 S 5 , SnS and LiCl sintered at temperatures of 550–700 °C, whose ionic conductivity and microstructures were studied respectively. XRD results show that the main phases of the resulting electrolyte were Li 7 PS 6 and LiCl, and the variation of the LiCl content and the sintering temperature led to a small change of phase composition. A suitable addition of LiCl could enhance the ionic conductivity. In addition, SEM images indicated that the grain size increased with the sintering temperature increase, resulting in that the resistance first decreased and then increased. The composite electrolyte with 14 wt% LiCl sintered at 600 °C had the best ionic conductivity of 5.89 × 10 −4 S cm −1 and the most chemical stability synchronously. [ABSTRACT FROM AUTHOR]

Dispersion of carbon fibers in the cement matrix remains a hot topic in the preparation of carbon fiber-reinforced cement-based composites (CFRC) because it affects greatly both the mechanical and electrical properties of the composites. In this work, a new dispersant hydroxyethyl cellulose was used with the aids of pre-dispersion by ultrasonic wave to realize the uniform distribution of chopped carbon fibers in the cement matrix. The fracture surface of the prepared CFRC was observed by scanning electron microscopy, the elemental distribution was investigated by energy dispersive spectroscopy, and the components was analyzed by X-ray diffraction. Influences of carbon fiber lengths and contents, water/cement weight ratio, molding process, curing time, and silica fume content over the conductivity of the CFRC composites were studied. The mechanism of conductivity was discussed. Results shown that the electrical resistivity intended to decrease with the increasing of carbon fiber contents. The mass fraction 0.6% of carbon fibers was a turning point. The concentration of hydroxyethyl cellulose between 1.66% and 1.86% was mostly beneficial for the dispersion of carbon fibers. The resistivity was increased first and decreased then with the increase of water/cement ratio. When the CFRC sample was prepared by the vibrating pressing method, the resistivity of the sample was reduced far greatly than that of the sample by the vibrating method. The incorporation of silica fume into the CFRC composites exerted not only a good effect on the dispersion of carbon fibers, but also increased the density of the composites to further influence the conductivity of the CFRC. [ABSTRACT FROM AUTHOR]

Medium-temperature sodium-bromine and sodium-iodine battery systems operating at 3.5 V and 3.0 V, respectively, are presented. The rechargeable molten-sodium systems work at approx. 100 °C and use aqueous bromine/bromide or iodine/iodide solutions as catholyte and sodium-ion conductive NaSICON (Na 3 Zr 2 Si 2.3 P 0.7 O 11.85 ) as solid electrolyte. The free halogen, which is formed upon charge, is complexed as highly soluble tribromide and triiodide, respectively. These systems can work in both, static and redox-flow setup, respectively, and aim at stationary energy storage applications. The sodium-halogen batteries were shown to run with high coulombic efficiency over several hundred hours. Long-term stability of the NaSICON ceramic material in contact with aqueous electrolytes, however, is still a concern. The sodium-bromine system suffers from a considerable bromine vapour pressure of the tribromide, whereas the sodium-iodine system was shown to operate in a stable manner with a catholyte allowing for a high total iodine concentration (≥2.0 M). Catholyte concentrations up to 2.75 M total iodine in redox-flow setup and up 3.7 M in static setup are possible without iodine precipitation and correspond to specific energies of 198 Wh kg −1 and 228 Wh kg −1 , respectively, on total active material level. [ABSTRACT FROM AUTHOR]

NASICON is one of the most promising sodium solid electrolytes that can enable the assembly of cheaper and safer sodium all-solid-state batteries. In this study, we perform a combined experimental and computational investigation into the effects of aliovalent doping in NASICON on both bulk and grain boundary (secondary phase) ionic conductivity. Our results show that the dopants with low solid solubility limits in NASICON lead to the formation of a conducting (less insulating) secondary phase, thereby improving the grain boundary conductivity measured by electrochemical impedance spectroscopy (including grain-boundary, secondary-phase, and other microstructural contributions) that is otherwise hindered by the poorly-conducting secondary phases in undoped NASICON. This is accompanied by a change in the Si/P ratio in the primary NASICON bulk phase, thereby transforming monoclinic NASICON to rhombohedral NASICON. Consequently, we have synthesized NASICON chemistries with significantly improved and optimized total ionic conductivity of 2.7 mS/cm. More importantly, this study has achieved an understanding of the underlying mechanisms of improved conductivities via doping (differing from the common wisdom) and further suggests a new general direction to improve the ionic conductivity of solid electrolytes via simultaneously optimizing the primary bulk phase and the microstructure (including grain boundary segregation and secondary phases). [ABSTRACT FROM AUTHOR]

We report two novel, earth-abundant lithium superionic conductors, Li3Y(PS4)2 and Li5PS4Cl2, that are predicted to satisfy the necessary combination of good phase stability, high Li+ conductivity, wide band gap and good electrochemical stability for solid electrolyte applications in all-solid-state rechargeable lithium-ion batteries. These candidates were identified from a high-throughput first-principles screening of the Li-P-S ternary and Li-M-P-S (where M is a non-redox-active element) quaternary chemical spaces, including candidates obtained by replacing Ag with Li in the Ag-P-S and Ag-M-P-S chemical spaces. An efficient tiered screening strategy was developed that combines topological analysis with ab initio molecular dynamics simulations to exclude rapidly candidates unlikely to satisfy the stringent conductivity requirements of lithium superionic conductors. In particular, we find Li3Y(PS4)2 to be an extremely promising candidate exhibiting a room-temperature Li+ conductivity of 2.16 mS/cm, which can be increased multifold to 7.14 and 5.25 mS/cm via aliovalent doping with Ca2+ and Zr4+, respectively. More critically, we show that the phase and electrochemical stability of Li3Y(PS4)2 is expected to be better than current state-of-the-art lithium superionic conductors. [ABSTRACT FROM AUTHOR]

Electrode–electrolyte interface (EEI) analysis is of great significance in the investigation of electrochemical (EC) processes. Current ex situ surface techniques provided rich information of the structural/chemical composition of the EEI. However, real-time and in situ monitoring of the EEI is in great demand for a better understanding of the dynamic changes of the redox systems. Mass spectrometry (MS) is a useful technique for mass-resolved analysis of various analytes with the capability of on-line measurement. In this review, we give a brief overview of the development of online EC–MS techniques. Recent advances of well-established EC–MS techniques, such as differential electrochemical mass spectrometry and EC–electrospray ionization mass spectrometry, and their applications are summarized. Specifically, some newly designed EC reactors coupled with state-of-the-art mass spectrometry for the detection of short-lived intermediate species are highlighted. [ABSTRACT FROM AUTHOR]

We performed variable-temperature synchrotron powder X-ray diffraction measurements and impedance spectroscopy under pressure for silver iodide (AgI) nanoparticles with a diameter of 11 nm. The superionic conducting α-phase of AgI nanoparticles was successfully stabilized down to at least 20 °C by applying a pressure of 0.18 GPa, whereas the transition temperature was 147 °C in bulk AgI at ambient pressure. To our knowledge, this is the first example of the α-phase of AgI existing stably at room temperature. [ABSTRACT FROM AUTHOR]

A high-conductivity solid electrolyte, LaZrO (LZO) added to LiLaZrTaO (LLZTO), was prepared via conventional solid-state reactions and sintered at 1100°C for 10 h, which is tens of Celsius degrees lower than the typical sintering temperature for LLZTO. The addition of LZO did not bring in any impurities. LZO acted as a sintering aid to densify the LLZTO from a relative density of 77% up to 90%, which was comparable to that of pure LLZTO sintered at 1200°C. The 6 wt.% LZO-LLZTO samples sintered at 1100°C and 1200°C exhibited a room-temperature conductivity of 1.92 × 10 S/cm and 5.84 × 10 S/cm, respectively, which were higher than that of pure LLZTO samples. Glass-like phases observed at grain boundaries in LZO-LLZTO ceramics indicated that LZO promoted the formation of the glass-like phases binding together LLZTO grains and thus leading to enhanced density and conductivity of LLZTO. [ABSTRACT FROM AUTHOR]

The Tl-1223 type phase superconductor with starting compositions (TlCr)BaCaCuO ( x = 0.4-0.8) has been prepared by the solid-state reaction method. The Aslamazov-Larkin (AL) theory was used to investigate the dimension of fluctuation-induced conductivity λ. The coherence length $\xi _{\mathrm {c}}\left (0 \right )$ Josephson coupling J, and anisotropy γ of the samples were calculated by using the Lawrence-Doniach (LD) theory. The highest T and T were observed in the x = 0.6 sample. All samples showed the Tl-1223 as the dominant phase. Cr substitution induced 2D to 3D conductivity transition, and the highest transition temperature, T , was observed for x = 0.5. The LD model showed a decrease in the coherence length, $\xi _{\mathrm {c}}\left (0 \right )$ and interlayer coupling for x = 0.6 and 0.7 samples These results showed that factors other than J and ξ (0) are more important in optimizing the superconducting transition temperature. Our results showed that excess conductivity occurs at a higher temperature for a higher- T superconductor. [ABSTRACT FROM AUTHOR]

Solid electrolyte Li 7 La 3 Zr 2 O 12 (LLZO) powder was successfully synthesized by co-precipitation method. The LLZO powder calcined at 850 °C with a tetragonal phase was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) showed that the particles sizes of LLZO precursor powder were in the range of 0.5 ~ 1 μm. LLZO pellets were sintered at different temperatures from 1150 to 1200 °C in air atmosphere. When the temperature was above 1150 °C, tetragonal LLZO would completely transform into cubic phase. The total ionic conductivity of LLZO pellet sintered at 1180 °C was 2.0 × 10 − 4 S cm − 1 at 30 °C, and the activation energy was 0.25 eV. This result indicates that high quality LLZO solid electrolytes can be obtained by chemical co-precipitation method. [ABSTRACT FROM AUTHOR]

Batteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li7La3Zr2O12 garnet as a Li-stable solid electrolyte. The material underwent a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6 %. When treated with a 2 M LiOH solution, the Li+/H+ exchange was reversed without any structural change. These observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries. [ABSTRACT FROM AUTHOR]

Good thermoelectric materials should have low thermal conductivity, high electrical conductivity, and Seebeck coefficient, which cannot be easily balanced in bulk materials. Exceptionally, the super-ionics in β-Cu2Se can favorably contribute large ionic electrical conductivity and a liquid-like thermal conductivity by Cu+ ions. In the previous work, the superionic mechanism was found to be enhanced by small and randomly orientated lamellae with alternating ordered Se ion monolayer and disordered Cu ion bilayers. Here, we further enhance the superionic mechanism by increasing and better aligning lamellae in bulk Cu1.94Al0.02Se, resulting in a large thermoelectric figure of merit of 2.62 at 756°C. [ABSTRACT FROM AUTHOR]

An exfoliated MoS2--C composite (E-MoS2--C) was prepared via simple chemical exfoliation and a hydrothermal method. The obtained E-MoS2--C was tested as an anode material for sodium ion batteries. High capacity (~400 mA h g-1)at 0.25C (100m Ag-1) was maintained over prolonged cycling life (100 cycles). Outstanding rate capability1 was also achieved with a capacity of 290 mA h g-1 at 5 C. [ABSTRACT FROM AUTHOR]

Proton conductivities of layered solid electrolytes can be improved by minimizing strain along the conduction path. It is shown that the conductivities ( σ) of multilayer graphene oxide (GO) films (assembled by the drop-cast method) are larger than those of single-layer GO (prepared by either the drop-cast or the Langmuir-Blodgett (LB) method). At 60 % relative humidity (RH), the σ value increases from 1×10−6 S cm−1 in single-layer GO to 1×10−4 and 4×10−4 S cm−1 for 60 and 200 nm thick multilayer films, respectively. A sudden decrease in conductivity was observed for with ethylenediamine (EDA) modified GO (enGO), which is due to the blocking of epoxy groups. This experiment confirmed that the epoxide groups are the major contributor to the efficient proton transport. Because of a gradual improvement of the conduction path and an increase in the water content, σ values increase with the thickness of the multilayer films. The reported methods might be applicable to the optimization of the proton conductivity in other layered solid electrolytes. [ABSTRACT FROM AUTHOR]

Highlights: [•] We verified the importance of Van Der Waals (VDW) interaction for the LGPS. [•] We studied the screening effect of Li+ on the Coulomb repulsion among S2−. [•] The Li distribution in the most energetically favored LGPS was then determined. [•] The Li diffusion barriers in the most favored LGPS were studied upon NEB method. [•] LGPS in the most favored configuration is a 3D rather than 1D superionic conductor. [ABSTRACT FROM AUTHOR]

A composite quasi-solid electrolyte is prepared by adding a layered Mg-Al hydrotalcite (LMAH) into the iodide/triiodide quasi-solid electrolyte including 4-tert-butylpyridine, which obviously improves the photovoltaic properties of quasi-solid dye-sensitized solar cells (DSSCs). When adding 5 wt% LMAH, the maximum photovoltaic conversion efficiency of DSSC is obtained, which reaches almost three times as large as that without LMAH. This enhancement effect is primarily explained by studying the nyquist spectrums, limiting current density, diffusion coefficient and photovoltaic conversion efficiency. [ABSTRACT FROM AUTHOR]

The electrochemical performances of LiTi2(PS4)3 (LTPS) with a 75Li2S-25P2S5 glass-ceramic solid electrolyte (SE) are investigated. In spite of irreversibility of structural changes, LTPS exhibits a high first discharge capacity of 455 mAh g-1 with good cycling retention of 76% at the 25th cycle between 1.5-3.5 V at 50 mA g-1 at 30°C. In sharp contrast, LTPS with a liquid electrolyte (LE) in a conventional cell loses half of its initial capacity after only 14 cycles. The much poorer performance of LTPS in the LE compared to that in the SE is believed to be associated with dissolution of LTPS into the LE. The results highlight the prospects of exploring electrode materials that are compatible with SEs for all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Highlights: [•] We visualized conduction pathways of lithium ions in the Li2S–P2S5 system. [•] We distinguished lithium stable and metastable regions in the conduction pathways. [•] We directly compared topology of the conduction pathways using activation energy. [ABSTRACT FROM AUTHOR]

Solid electrolytes in the system LiS-PS are attractive for all-solid-state lithium batteries since the electrolytes have high lithium ion conductivities and wide electrochemical windows. In particular, the 75LiS·25PS (mol%) glass showed the highest stability to moisture in the system LiS-PS because the amount of HS gas generated from the glass was the smallest in the system LiS-PS. In this study, several additives such as metal sulfides and metal oxides (FeS, CuO, etc.) were mixed with the 75LiS·25PS glass in order to suppress HS gas generation from the sulfide glasses in air. The addition of more than 30 mol% FeS greatly decreased HS gas generation from the sulfide glass in air. In the case of the FeS addition, sulfur crystal was precipitated and the 75LiS·25PS glass changed to LiPO crystal after a reaction with water. On the other hand, the addition of 30 mol% CuO dramatically decreased HS gas generation from the sulfide glass in air. In the case of the CuO addition, CuPS crystal was precipitated after the reaction with water. Furthermore, the 75LiS·25PS glass added with 30 mol% FeS or CuO showed relatively high conductivities of more than 10 S cm at room temperature. Therefore, the 75LiS·25PS glass added with FeS or CuO was expected to be a suitable solid electrolyte material for all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we report an X-ray diffraction (XRD), Raman spectroscopy and electrochemical study of the Li10GeP2S12 lithium ion conducting solid electrolyte. The XRD results confirm the structure of the electrolyte, the Raman spectroscopy evidences the composite nature of the solid solution showing some spectral features typical of the starting Li2S, GeS2, and P2S5 materials, whereas a band peaked at about 495 cm−1 is identified as the specific fingerprint of the Li10GeP2S12 compound. The electrochemical studies, involving impedance spectroscopy, scan voltammetry and chrono-amperometry, demonstrate an ionic conductivity of the order of 10−3 S cm−1 over a wide temperature range with activation energy of approximately 0.1 eV, lithium transference of 0.99 and a stability window extending from 0 V to 6 V vs. Li. Further tests yield preliminary results obtained by Potentiodynamic Cycling with Galvanostatic Acceleration (PGCA) evaluation, which were carried out on a lithium metal anode as well as on lithium iron phosphate LiFePO4 and lithium nickel manganese oxide LiNi0.5Mn1.5O4 cathodes in cells using Li10GeP2S12 as electrolyte. The material properties described above in conjunction with these tests identify Li10GeP2S12 as a very promising electrolyte for the development of advanced solid-state batteries. [Copyright &y& Elsevier]

The thermal behavior of the oxide ion-conducting solidelectrolyteBi4YbO7.5was investigated using a combinationof variable temperature X-ray and neutron powder diffraction, thermalanalysis (DTA and TGA), and ac impedance spectroscopy. The title compoundshows a fluorite-type structure throughout the measured temperaturerange (20–850 °C), with a phase separation at ca. 600°C into a cubic δ-type phase and an orthorhombic phaseof assumed stoichiometry Bi17Yb7O36. This type of transition is a relatively common feature in bismuthoxide-based systems and can limit their practical application. Here,the transition was carefully studied using isothermal measurements,which showed that it is accompanied by changes in oxide-ion stoichiometry,as well as significant disorder in the oxide ion sublattice in theδ-type phase. These results correlate with the observed electricalbehavior. Analysis of the total neutron scattering through reverseMonte Carlo (RMC) modeling reveals details of the coordination environmentsfor both cations. The oxide-ion vacancy distribution seems to be consistentwith a favoring of ⟨100⟩ vacancy pairs, although ⟨110⟩vacancy pairs exhibit the highest frequency as they have the maximumlikelihood. A vacancy ordering model based on three vacancies percell is presented. [ABSTRACT FROM AUTHOR]

Composite materials with ion-conductivity based on solid electrolytes and ion-exchange membranes attracted great interest of researchers and are considered as promising materials for various electrochemical devices. The mane laws of ion transport in such systems are discussed in this review. The most important factor contributing to the improvement of ionic conductivity of solid electrolytes is a defect formation on the interface. In the case of hybrid ion-exchange membranes the most important factor is the change in the pores and channels structure. The application of these materials in fuel cells is discussed also, which became the most important task in recent years. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical oxygen reduction behavior for a half cell composed of a mixed ionic and electronic conducting (MIEC) oxide and an oxygen excess-type solid electrolyte was investigated. A perovskite-type MIEC oxide, (La0.6Sr0.4)(Co1−y Fe y )O3−δ (LSCF), was employed as a base material for an electrode catalyst of oxygen reduction reaction. As an electrolyte, Al-doped lanthanum silicate [La10(Si5.8Al0.2)O26.9 (ALSO)] was used, which is a new class of oxide ion conductors with apatite-type structure. The evaluated polarization resistance, R pol , for the reaction largely depended on y, and the minimum resistance was obtained for y = 0.2. The R pol value was 0.3 Ω cm2 at 1073 K in ambient air [P(O2) = 2.1 × 104 Pa] for y = 0.2. To improve the performance, introduction of silver nano-particles onto the LSCF particles was studied. With the Ag-modification, R pol at 1073 K could be minimized toward 0.08 Ω cm2. The cathodic overpotential of the electrode evaluated from DC polarization at 1073 K was 18 mV at 0.1 A cm−2. [Copyright &y& Elsevier]

Solid solutions based on CsFeO in CsFeAO systems (A = P, V) were synthesized. Their crystal structure and the temperature and concentration dependences of the total conductivity and its electronic component were studied. The ranges of temperature and composition in which cesium-cation conductivity was dominant were determined. The obtained data were compared with the results of studies of other cesium-conducting solid electrolytes. [ABSTRACT FROM AUTHOR]

New potassium-conducting solid electrolytes in the mixed ferrite-aluminate K(FeAl)VO and K(FeAl)PO are synthesized and studied. In the first system, the conductivity only slightly depends on the composition; therefore, the composition of solid electrolyte can be optimized with respect to the conductivity-stability characteristics. In the second system, extremes and considerable negative deviations from the additivity are observed in the conductivity isotherms. Possible reasons for this phenomenon are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Air conditioning and lighting costs can be reduced substantially by changing the optical properties of “intelligent windows.” The electrochromic devices studied to date have used copper as an additive. Copper, used here as an electrochromic material, was dissolved in an aqueous animal protein-derived gel electrolyte. This combination constitutes the electrochromic system for reversible electrodeposition. Cyclic voltammetry, chronoamperometric and chromogenic analyses indicated that were obtained good conditions of transparency (initial transmittance of 70%), optical reversibility, small potential window (2.1V), variation of transmittance in visible light (63.6%) and near infrared (20%) spectral regions. Permanence in the darkened state was achieved by maintaining a lower pulse potential (−0.16V) than the deposition potential (−1.0V). Increasing the number of deposition and dissolution cycles favored the transmittance and photoelectrochemical reversibility of the device. The conductivity of the electrolyte (10−3 S/cm) at several concentrations of CuCl2 was determined by electrochemical impedance spectroscopy. A thermogravimetric analysis confirmed the good thermal stability of the electrolyte, since the mass loss detected up to 100°C corresponded to water evaporation and decomposition of the gel started only at 200°C. Micrographic and small angle X-ray scattering analyses indicated the formation of a persistent deposit of copper particles on the ITO. [Copyright &y& Elsevier]

Abstract: Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. However, it is difficult to sinter it to high density at a reasonable temperature. Moreover, it presents a high grain boundary resistivity at intermediate temperatures. Flash grain welding was applied to compacted samples, starting from a temperature of 910°C and applying, for a short time, an ac electric polarization of 40V, 1000Hz. At that frequency, the resulting current flows through the grain boundaries promoting a welding via a local Joule heating. A large decrease of the grain boundary resistivity was observed by impedance spectroscopy. Scanning electron microscopy observations of polished and etched surfaces revealed highly sintered regions. Attempts were also made to combine flash grain welding with conventional sintering. [Copyright &y& Elsevier]

X-ray photoelectron spectroscopy (XPS) and symmetric electrochemical impedance spectroscopy (EIS) are carried out to identify and determine the nature of the solid electrolyte interface (SEI) formation on TiO2 rutile anodes in lithium ion batteries. The recorded XPS spectra (O1s, C1s, P2p and Li1s and Ti2p) evidence an SEI layer formation at 0.8 V vs. Li/Li+ in a TiO2/Li cell with a lithium reference and an organic electrolyte (LiPF6 in EC : DMC (1 : 1 by wt%)). When the cell is discharged down to 0.1 V, the SEI mainly consists of ether and carbonyl groups and some alcohol or alkoxide groups. Upon charge the SEI additionally evidences some carboxylic groups. EIS measurements exhibit an additional RQ element at 0.8 V, supporting the formation of the SEI at this potential. The EIS evaluation shows that the SEI is mainly formed in the first cycle but evolves further on in the following cycles. [ABSTRACT FROM AUTHOR]

La2/3-xLi3xTiO3 (LLT, x = 0.1 and 0.167) thin films were grown on (001)-oriented SrTiO3 (STO) substrates by pulsed laser deposition. The resultant LLT films were heteroepitaxially grown with atomically flat surfaces. Although the films considered to be single crystalline, they were composed of 90°-rotated multi domains (∼5 nm in size) with epitaxial relationships of (100) [001] LLT || (001) [100] STO and (100) [010] LLT || (001) [100] STO. The bulk conductivity of the LLT (x = 0.1) films was 2.5 × 10-2 S cm-1 at 190 °C, comparable to that of a bulk single crystalline LLT. Single crystalline LLT thin films with atomically flat surfaces should help clarify interfacial lithium-ion conductivity. [ABSTRACT FROM AUTHOR]

We have prepared an all-solid-thin film electrochromic device (ECD), consisting of layers ITO / NiO / ZrO2 / WO3 / ITO using the PVD method. The WO3 is used as an electrochromic layer, NiO as an ion-storage layer, and ZrO2 as a solid electrolyte layer in the all-solid-thin film ECD. The optical transmittance varied between 3-59 %. The device shows the coloration and bleaching time of 120 s and 2 s, respectively, with a good memory effect and desirable cycle-life. [ABSTRACT FROM AUTHOR]

Abstract: Impedance spectroscopy at high electric field strengths ranging from 73kV/cm to 146kV/cm was used to measure the low-field conductivity and third-order nonlinear conductivity of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C6mim] [NTf2]. The measurements were carried out at three different temperatures close to the glass-transition temperature T g =189K. The third-order conductivity coefficient σ 3′ was determined from higher-order harmonic contributions to the measured ionic currents. Apparent jump distances a app derived from the low-field and the third-order dc conductivity were found to be similar to those derived for solid electrolytes. However, in contrast to various solid electrolytes, the frequency-dependent third-order conductivity σ 3′ shows no change in sign in the crossover regime to dc to dispersive conductivity. [Copyright &y& Elsevier]

Thermoelectric devices, which can generate electricity from waste heat, offer an attractive pathway for addressing an important niche in the globally growing landscape of energy demand. In the past few decades, the search for high-efficiency thermoelectrics has been guided by the concept of ‘phonon-glass electron-crystal’ (PGEC), i.e. an ideal thermoelectric material should have high carrier mobility and low thermal conductivity. Although remarkable progress has already been made along this line, the efficiency of thermoelectrics is still too poor to compete with other electricity producing methods. Ordered-disordered material, an emerging trend of high performance thermoelectrics under the concept of PGEC, is a new hot topic in the current thermoelectric research community. Taking superionic phase silver telluride (α-Ag2Te) as an example, we performed a comprehensive study of the thermal transport properties and of its physical mechanism by means of equilibrium molecular dynamic simulations. The results show that the thermal conductivity of α-Ag2Te is intrinsically very low. By analyzing the different contributions to the overall thermal conductivity, we revealed for the first time from atomistic simulations that the vibration of the Te2− sublattice dominates the thermal transport of α-Ag2Te, while the collision between the randomly diffusing Ag+ ions and the Te2− sublattice yields a significant negative contribution to the thermal transport. We also studied the effect of isotropic compressive stain and carrier concentration on the thermal conductivity of α-Ag2Te. It has been found that the thermal conductivity can be largely reduced by applying compressive strain or with stoichiometric quantity modulation. Our studies shed light on the governing mechanism of thermal transport in ordered-disordered materials and could offer useful guidance for engineering the thermal transport properties of superionic conductors in terms of enhancing their thermoelectric performance. [ABSTRACT FROM AUTHOR]