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The formation of an electric double‐layer (EDL) is an important phenomenon for many research areas, including energy storage technology. Although EDL is well‐known in electrochemistry, most of the studies involve the characterization of liquid electrolyte/electrode interfaces, and only a limited number of studies in solid‐solid contacts, such as solid electrolyte/electrode interface are available. This paper employed electrochemical impedance spectroscopy (EIS) to systematically investigate the influence of experimental factors in the interfacial capacitance arising from the electrode polarization in a lithium disilicate glass/gold electrode interface. It analyzed the influence of a.c. input voltage amplitude, samples' roughness (mechanical and chemomechanical polishing) and thickness, range of applied frequency and temperature, and the number of impedance cycles. In short, it was found that an input voltage range of 15–60 mV is indicated to minimize potential electrochemical processes during electrode polarization, where the data is reproducible from the second measurement cycle onward. Smoother surfaces closely approximated ideal electrode spike behavior, with surface treatment exhibiting influence on interfacial capacitance values. Moreover, as expected, we observed an increase in relative permittivity values with increasing thickness, accompanied by decreased capacitance values. Finally, by employing optimal experimental conditions and analyzing the inflection frequency (finflection${{f}_{inflection}}$) of the ε′$\varepsilon ^{\prime}$ versus log(f$f$) curve, we determined that the ratio between effective charge carriers (ne${{n}_e}$) and the total number of charge carriers (nt${{n}_t}$) nent$\frac{{{{n}_e}}}{{{{n}_t}}}$ falls within the range of 5–12% between 130°C and 280°C. [ABSTRACT FROM AUTHOR]

Garnet-type solid electrolytes stand out as promising Li-ion conductors for the next-generation batteries. It has been demonstrated that the inherent properties of garnets can be tailored by introducing various dopants into their crystal structures. Recently, there has been a growing interest in the concept of high entropy stabilization for materials design. In this study, we synthesized high-entropy garnets denoted as Li6La3Zro.7Tio.3Tao.5Sbo.5Oi2 (LLZTTSO), wherein Ti, Sb, and Ta occupy the Zr site. The formation of the cubic garnet phase in LLZTTSO was confirmed through X-ray diffraction (XRD), and the resulting lattice parameter agreed with predictions made using computational methods. Despite the substantial porosity (relative density 80.6%) attributed to the low sintering temperature, LLZTTSO exhibits a bulk ionic conductivity of 0.099 mS cm-1 at 25°C, and a total ionic conductivity of 0.088 mS cm-1, accompanied by an activation energy of 0.497 eV. Furthermore, LLZTTSO demonstrates a critical current density of 0.275mAcm-2 at 25°C, showcasing its potential even without any interfacial modification. [ABSTRACT FROM AUTHOR]

This study explores multi-component garnet-based materials as solid electrolytes for all-solid-state lithium batteries. Through a combination of computational and experimental approaches, we investigate the thermodynamic and structural properties of lithium lanthanum zirconium oxide garnets doped with various elements. Applying density functional theory, the influence of dopants on the thermodynamic stability of these garnets was studied. Probable atomic configurations and their impact on materials' properties were investigated with the focus on understanding the influence of these configurations on structural stability, phase preference, and ionic conductivity. In addition to the computational study, series of cubic-phase garnet compounds were synthesized and their electrochemical performance was evaluated experimentally. Our findings reveal that the stability of cubic phase in doped Li-garnets is primarily governed by enthalpy, with configurational entropy playing a secondary role. Moreover, we establish that the increased number of doping elements significantly enhances the cubic phase's stability. This in-depth understanding of materials' properties at atomic level establishes the basis for optimizing high-entropy ceramics, contributing significantly to the advancement of solid-state lithium batteries and other applications requiring innovative material solutions. [ABSTRACT FROM AUTHOR]

The need to develop safe solid-state lithium batteries has stimulated intense research efforts for Li+ solid electrolytes. However, the low conductivity limits the development of NASICON LiZr 2 (PO 4) 3 (LZP) electrolyte. Here, the doping effects of Ta on the structure, surface morphologies and electrochemical properties of Li 1- x Zr 2- x Ta x (PO 4) 3 (LZTP, x = 0, 0.01, 0.02, 0.04, 0.06 and 0.08) solid electrolyte were analyzed. LZTP was prepared using a simple solid-state reaction route, followed by sintering at 1200 °C for 12 h. A proper content of Ta5+ substitution for Zr4+ is beneficial to stabilize the high conductive rhombohedral (α) phase of LZP at room temperature. Doping Ta5+ is conducive to unblocking of Li+ at the M1 site and facilitates the occupation of Li+ at the M2 site, thereby expanding the pathway for Li+ conduction. Rietveld refinement data demonstrated that the Zr–O and P–O bond lengths (d Zr-O and d P-O) increased with a decrease in Zr–O–P bond angles (θ Zr-O-P) as x rose. The distortions in the ZrO 6 octahedron may weaken the coulomb attraction in Li+-O2-, resulting in a lower activation energy (E a) and a higher Li+ conductivity. The highest room-temperature conductivity (6.06 × 10−5 S cm−1) was obtained at x = 0.06, which reached 1.5 × 10−4 S cm−1 at 50 °C. The E a was found to decrease from 0.388 eV (x = 0) to 0.306 eV (x = 0.06). In addition, Ta doping resulted in improved connectivity and reduced pore formation, which also contributed to the decrease in resistance. The Raman spectrum demonstrated that some phonon modes of bending vibration in PO 4 were degenerate and external modes became too weak to be observed or even disappeared as Ta content increased. This change in the modes also had an impact on the Li+ conductivity. Overall, the LZTP-0.06 appears to be a promising candidate for the solid electrolyte. [ABSTRACT FROM AUTHOR]

Garnet-type solid electrolytes stand out as promising Li-ion conductors for the next-generation batteries. It has been demonstrated that the inherent properties of garnets can be tailored by introducing various dopants into their crystal structures. Recently, there has been a growing interest in the concept of high entropy stabilization for materials design. In this study, we synthesized high-entropy garnets denoted as Li6La3Zr0.7Ti0.3Ta0.5Sb0.5O12 (LLZTTSO), wherein Ti, Sb, and Ta occupy the Zr site. The formation of the cubic garnet phase in LLZTTSO was confirmed through X-ray diffraction (XRD), and the resulting lattice parameter agreed with predictions made using computational methods. Despite the substantial porosity (relative density 80.6%) attributed to the low sintering temperature, LLZTTSO exhibits a bulk ionic conductivity of 0.099 mS cm−1 at 25°C, and a total ionic conductivity of 0.088 mS cm−1, accompanied by an activation energy of 0.497 eV. Furthermore, LLZTTSO demonstrates a critical current density of 0.275 mA cm−2 at 25°C, showcasing its potential even without any interfacial modification.

This study explores multi-component garnet-based materials as solid electrolytes for all-solid-state lithium batteries. Through a combination of computational and experimental approaches, we investigate the thermodynamic and structural properties of lithium lanthanum zirconium oxide garnets doped with various elements. Applying density functional theory, the influence of dopants on the thermodynamic stability of these garnets was studied. Probable atomic configurations and their impact on materials’ properties were investigated with the focus on understanding the influence of these configurations on structural stability, phase preference, and ionic conductivity. In addition to the computational study, series of cubic-phase garnet compounds were synthesized and their electrochemical performance was evaluated experimentally. Our findings reveal that the stability of cubic phase in doped Li-garnets is primarily governed by enthalpy, with configurational entropy playing a secondary role. Moreover, we establish that the increased number of doping elements significantly enhances the cubic phase’s stability. This in-depth understanding of materials’ properties at atomic level establishes the basis for optimizing high-entropy ceramics, contributing significantly to the advancement of solid-state lithium batteries and other applications requiring innovative material solutions.

The sodium ion–based materials have interesting physical properties which make them suitable for industrial applications. In this paper, we focus our work on sodium ytterbium phosphate NaYbP2O7, prepared by the solid-state method. It is found that NaYbP2O7 crystallizes in the monoclinic system with P121/n1 space group. Impedance analysis shows that this compound exhibits semiconductor behavior and that the conduction mechanism is thermally activated. AC conductivity measurements show that NaYbP2O7 can be a good ionic conductor with an activation energy value up to 0.94eV. The frequency dependence of conductivity is probably caused by the jump of Na ions between octahedral sites of the olive framework. Such properties of NaYbP2O7 make it suitable as an ionic conductor. [ABSTRACT FROM AUTHOR]

Additive manufacturing of solid-state batteries is advantageous for improving the power density by increasing the geometric complexity of battery components, such as electrodes and electrolytes. In the present study, bulk three-dimensional Li _1+ _x Al _x Ti _2− _x (PO _4 ) _3 (LATP) electrolyte samples were prepared using the laser powder bed fusion (L-PBF) additive manufacturing method. Li _3 PO _4 (LPO) was added to LATP to compensate for lithium vaporization during processing. Chemical compositions included 0, 1, 3, and 5 wt. % LPO. Resulting ionic conductivity values ranged from 1.4 × 10 ^−6 –6.4 × 10 ^−8 S cm ^−1 , with the highest value for the sample with a chemical composition of 3 wt. % LPO. Microstructural features were carefully measured for each chemical composition and correlated with each other and with ionic conductivity. These features and their corresponding ranges include: porosity (ranging from 5% to 19%), crack density (0.09–0.15 mm mm ^−2 ), concentration of residual LPO (0%–16%), and concentration and Feret diameter of secondary phases, AlPO4 (11%–18%, 0.40–0.61 µ m) and TiO2 (9%–11%, 0.50–0.78). Correlations between the microstructural features and ionic conductivity ranged from −0.88 to 0.99. The strongest negative correlation was between crack density and ionic conductivity (−0.88), confirming the important role that processing defects play in limiting the performance of bulk solid-state electrolytes. The strongest positive correlation was between the concentration of AlPO4 and ionic conductivity (0.99), which is attributed to AlPO4 acting as a sintering aid and the role it plays in reducing the crack density. Our results indicate that additions of LPO can be used to balance competing microstructural features to design bulk three-dimensional LATP samples with improved ionic conductivity. As such, refinement of the chemical composition offers a promising approach to improving the processability and performance of functional ceramics prepared using binderless, laser-based additive manufacturing for solid-state battery applications.

Solid inorganic and polymeric electrolytes have the potential to enable rechargeable batteries with higher energy densities, compared to current lithium-ion technology, which uses liquid electrolyte. Inorganic materials such as ceramics and glasses conduct lithium ions well, but they are brittle, which makes incorporation into a battery difficult. Polymers have the flexibility for facile use in a battery, but their transport properties tend to be inferior to inorganics. Thus, there is growing interest in composite electrolytes with inorganic and organic phases in intimate contact. This article begins with a discussion of ion transport in single-phase electrolytes. A dimensionless number (the Newman number) is presented for quantifying the efficacy of electrolytes. An effective medium framework for predicting transport properties of composite electrolytes containing only one conducting phase is then presented. The opportunities and challenges presented by composite electrolytes containing two conducting phases are addressed. Finally, the importance and status of reaction kinetics at the interfaces between solid electrolytes and electrodes are covered, using a lithium-metal electrode as an example.

Solid-state electrolytes can offer improved lithium-ion battery safety while potentially increasing the energy density by enabling alkali metal anodes. There have been significant research efforts to improve the ionic conductivity of solid-state electrolytes and the electrochemical performance of all-solid-state batteries; however, the root causes of their poor performance - interfacial reaction and subsequent impedance growth - are poorly understood. This is due to the dearth of effective characterization techniques for probing these buried interfaces. In situ and operando methodologies are currently under development for solid-state interfaces, and they offer the potential to describe the dynamic interfacial processes that serve as performance bottlenecks. This article highlights state-of-the-art solid-solid interface probing methodologies, describes practical limitations, and describes a future for dynamic interfacial characterization.

The design and production features of a solid oxide fuel cell greatly impact its microstructure and performance; however, these factors are frequently omitted in related studies. In this work, the influence of the design and formation factors of a solid oxide fuel cell on its performance and long-term stability is studied. The sintering process of multilayer half-cells is studied by heating microscopy and the optimal sintering strategy is identified. We show here the importance of the sintering strategy and suggest an approach for SOFC design that results in a stable in time performance. The electrochemical performance is evaluated by impedance spectroscopy and the distribution of relaxation times (DRT) technique. It is shown that the absence of the barrier layer leads to a decrease in the SOFC performance by 22.5% as-sintered and continues to drop down during the exposure of 850 °C for 400 h. The impregnation of the cathode and anode by Pr(NO3)3 and Ce(NO3)3 improves electrochemical performance by 15% and this increase withstands a heat treatment at least for 215 h without any noticeable degradation. The most stable in time performance of the cell with impregnated electrodes and the barrier layer is 515.3 mW × cm−2 (H2 + 3% H2O used as fuel, air + 3% H2O as oxidizer). [ABSTRACT FROM AUTHOR]

Developing high specific energy Lithium-ion (Li-ion) batteries is of vital importance to boost the production of efficient electric vehicles able to meet the customers’ expectation related to the electric range of the vehicle. One possible pathway to high specific energy is to increase the operating voltage of the Li-ion cell. Cathode materials enabling operation above 4.2 V are available. The stability of the positive electrode-electrolyte interface is still the main bottleneck to develop high voltage cells.Moreover, important research efforts are devoted to the substitution of graphite anodes with Li metal: this would improve the energy density of the cell dramatically. The use of metallic lithium is prevented by the dendrite growth during charge, with consequent safety problems. To suppress the formation of dendrites solid-state electrolytes are considered the most promising approach.For these reasons the present review summarizes the most recent research efforts in the field of high voltage solid-state electrolytes for high energy density Li-ion cells.

We present a computational approach for identifying the important descriptors of the ionic conductivities of lithium solid electrolytes. Our approach discriminates the factors of both bulk and grain boundary conductivities, which have been rarely reported. The effects of the interrelated structural (e.g. grain size, phase), material (e.g. Li ratio), chemical (e.g. electronegativity, polarizability) and experimental (e.g. sintering temperature, synthesis method) properties on the bulk and grain boundary conductivities are investigated via machine learning. The data are trained using the bulk and grain boundary conductivities of Li solid conductors at room temperature. The important descriptors are elucidated by their feature importance and predictive performances, as determined by a nonlinear XGBoost algorithm: (i) the experimental descriptors of sintering conditions are significant for both bulk and grain boundary, (ii) the material descriptors of Li site occupancy and Li ratio are the prior descriptors for bulk, (iii) the density and unit cell volume are the prior structural descriptors while the polarizability and electronegativity are the prior chemical descriptors for grain boundary, (iv) the grain size provides physical insights such as the thermodynamic condition and should be considered for determining grain boundary conductance in solid polycrystalline ionic conductors.

La2Mo2O9 based Tb-doped compound, La2-xTbxMo2O9 (x=0.1, 0.2, 0.5), was synthesized and characterised by EIS studies. The frequency and temperature dependent dielectric, electric modulus and ac conductivity studies have been done. Different formalisms have been used to understand relaxation mechanism in our compound. The conductivity in these specimens appears to be due to mobility of oxygen ions.

Li 2 O-2B 2 O 3 coated Li 4 Ti 5 O 12 anode with protected particle surface and fast ion transfer exhibit desired rate capability and cycling stability for lithium ion batteries. Li 2 O-2B 2 O 3 (LBO) ionic conductor with high conductivity plays an important role in boosting the rate performance and cycling stability of Li 4 Ti 5 O 12 (LTO) anode for lithium-ion batteries by preventing direct exposure of LTO to the electrolyte. Herein, the effect of LBO coating layer on lithium ion (Li+) storage performance is investigated in detail by adjusting the adding amount of LBO precursor dispersion. LTO coated with 2 wt% LBO achieves an optimum performance with a specific capacity of 172.9 mA h g−1 at a current density of 0.1 A g−1, an improved rate capability (specific capacity of 127.9 mA h g−1 is maintained when the current density is 20 times than 0.1 A g−1) and a remarkable cycling stability (capacity retention of 94.2% after 4000 cycles at 2.0 A g−1). These LBO-LTO composites are competitive and promising candidates for electrochemical energy storage and other applications. [ABSTRACT FROM AUTHOR]

Ionic liquid (IL) based gel polymer electrolytes (GPEs) are being investigated extensively at present as substitutes for conventional GPEs based on a polymer, a salt and solvents. The main reason behind this is the drawbacks in usage of solvents. IL based GPEs have been employed for energy storage devices such as batteries and super capacitors due to their interesting mechanical, physical and electrochemical properties. This study focused on synthesis preparation and characterization of an IL based GPE consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP), zinc trifluoro metha -nesulfonate (Zn(CF3SO3)2 - ZnTF) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF). Thin film samples were prepared using solvent casting method. The optimized composition was found to be 1 PVdF-co-HFP: 1 1E3MITF: 3 ZnTF (by weight basis). This mechanically stable, thin film has the maximum room temperature conductivity of 7.42×10-3 S cm-1. Conductivity variation with temperature follows Vogel - Tamman - Fulcher (VTF) behavior confirming the relation of conductivity mechanism with the free volume theory. The IL based GPE is a purely an ionic conductor having a considerable anionic contribution. It shows stability up to 2.5 V which is very much convenient from a practical point of view. Oxidation and reduction of Zn takes place at the potentials of 0.5 V and –0.5 V, respectively. In addition, Zn platting and stripping occurs only on the Zn electrodes but not on the stainless steel (SS) electrodes. Impedance measurements taken for the GPE continuously for a long period of time exhibited a satisfactory stability with Zn electrodes.

We present a computational approach for identifying the important descriptors of the ionic conductivities of lithium solid electrolytes. Our approach discriminates the factors of both bulk and grain boundary conductivities, which have been rarely reported. The effects of the interrelated structural (e.g. grain size, phase), material (e.g. Li ratio), chemical (e.g. electronegativity, polarizability) and experimental (e.g. sintering temperature, synthesis method) properties on the bulk and grain boundary conductivities are investigated via machine learning. The data are trained using the bulk and grain boundary conductivities of Li solid conductors at room temperature. The important descriptors are elucidated by their feature importance and predictive performances, as determined by a nonlinear XGBoost algorithm: (i) the experimental descriptors of sintering conditions are significant for both bulk and grain boundary, (ii) the material descriptors of Li site occupancy and Li ratio are the prior descriptors for bulk, (iii) the density and unit cell volume are the prior structural descriptors while the polarizability and electronegativity are the prior chemical descriptors for grain boundary, (iv) the grain size provides physical insights such as the thermodynamic condition and should be considered for determining grain boundary conductance in solid polycrystalline ionic conductors. [ABSTRACT FROM AUTHOR]

Na2FeP2O7 (NFP) ceramics show potential application as the active material for sodium ion batteries. In this study, NFP ceramics were irradiated with infrared laser light with a wavelength of 1 µm. Fe2+ ions allowing local heating and resulting in instantaneous melting and rapid cooling for glass formation. The results of differential thermal analysis and X‐ray diffraction suggest that the laser‐irradiated part is vitrified and that rapid cooling is achieved to prevent recrystallization. It was possible to form a molten pattern withan output of 0.22 W and a scanning rate of up to 3mm/s of laser light. Irradiation of laser light on NFP powder on NASICON‐type Na3Zr2Si2PO12 solid electrolyte ceramic enabled the formation of a dense glassy NFP phase of several tenth‐micrometer depths on solid electrolyte ceramic. This technique is a promising process mainly for developing an oxide‐based all‐solid‐state battery because the contact interface can form instantaneously without external mechanical pressure. [ABSTRACT FROM AUTHOR]

Due to its high capacity and low density, lithium metal is considered as one of the most promising anodes for next-generation lithium batteries. However, the problems of dendrite and volume change are the main obstacles to limit its further development. Therefore, it is of great significance to realize the stable plating and stripping of lithium metal. The stability of lithium metal can be improved by compositing lithium with conductor materials, but the effect of conductor materials on lithium composite anode needs to be further studied. Herein, ionic or electronic conductor powders are introduced into the interior of lithium metal by hot-melt mixed coating method; Li/Cu, Li/Zn, and Li/Li3N composite anodes are prepared; and their electrochemical performances in solid and liquid batteries are studied. The results show that plating and stripping of lithium in composite anodes will take place preferentially around electronic or ionic conductor, rather than around lithium itself. For liquid batteries, the introduction of electronic conductor in lithium composite anode will make the electric field distribution more uniform and thus make the lithium deposition more stable, while the introduction of ionic conductor in composite anodes can improve the electrochemical stability of composite anodes in solid-state batteries. The capacity of the Li/Cu-LFP battery was 42.5 mAh g−1 after 500 cycles at 10 °C, corresponding to the 77% retention of its initial capacity. [ABSTRACT FROM AUTHOR]

DC electrical degradation as a form of dielectric and resistance breakdown is common in thin‐film devices including resistance‐switching memory. To obtain design data and to probe the degradation mechanism, highly accelerated lifetime tests (HALT) are often conducted at higher temperatures with thicker samples. While the mechanism is well established in semiconducting oxides such as perovskite titanates, it is not in stabilized zirconia and other fast oxygen‐ion conductors that have little electronic conductivity. Here we model the mechanism by an oxygen‐driven, transport‐limited, metal‐insulator transition, which finds support in rich experimental observations—including in situ videos and variable temperature studies—of yttria‐stabilized zirconia. This demonstrates that although (electro) reduction does not appreciably alter oxygen stoichiometry in stabilized zirconia, which is fixed by the dopant concentration, it can still raise the chemical potential of electrons enough to eventually reach the conduction‐band level, thereby triggering the insulator‐to‐metal transition and resistance degradation. These results are contrasted with the findings in semiconducting titanates and resistance memory, and to provide new insight into ceramic processing with extremely rapid heating and cooling such as flash sintering and melt processing. [ABSTRACT FROM AUTHOR]

The 70-year history of scientific endeavor of solid state ionics research in Japan is reviewed to show the contribution of Japanese scientists to the basic science of solid state ionics and its applications. The term ‘solid state ionics’ was defined by Takehiko Takahashi of Nagoya University, Japan: it refers to ions in solids, especially solids that exhibit high ionic conductivity at a fairly low temperature below their melting points. During the last few decades of exploration, many ion conducting solids have been discovered in Japan such as the copper-ion conductor Rb4Cu16I7Cl13, proton conductor SrCe1–xYxO3, oxide-ion conductor La0.9Sr0.9Ga0.9Mg0.1O3, and lithium-ion conductor Li10GeP2S12. Rb4Cu16I7Cl13 has a conductivity of 0.33 S cm–1 at 25 °C, which is the highest of all room temperature ion conductive solid electrolytes reported to date, and Li10GeP2S12 has a conductivity of 0.012 S cm–1 at 25 °C, which is the highest among lithium-ion conductors reported to date. Research on high-temperature proton conducting ceramics began in Japan. The history, the discovery of novel ionic conductors and the story behind them are summarized along with basic science and technology.

The formation phenomena of silver carbonate (Ag2CO3)–silver iodide (AgI) solid solutions were investigated by X-ray diffraction, thermogravimetry-differential thermal analysis, and electrical conductivity measurement. Results revealed that AgI and Ag2CO3 reacted with each other when mixed at room temperature. The reaction products were classified into three types: (1) AgI-based solid solutions in the AgI-rich region for x = 10% or less in x Ag2CO3–(1 − x) AgI; (2) Ag2CO3-based solid solutions in the Ag2CO3-rich region for x = 60% or more; and (3) silver carbonate iodides in the intermediate range for x between 10% and 60%. For the AgI-based solid solutions, the incorporation of Ag2CO3 into the AgI lattice expanded the unit cell and enhanced electrical conductivity. The solubility limit of Ag2CO3 into the AgI lattice estimated from the differential thermal analysis was x ≈ 5%.

To improve the stability and performance of the cathode materials, an ionic conductor layer was coated successfully on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 (LMNC) microspheres. The structural analysis confirmed that LiV3O8 coating did not change the basic structure of LMNC, and all obtained materials are solid solutions with a good-layered structure and a good crystallinity. The microscopy measurement showed that the thickness of the coating layer for the LV-3 sample is about 2.5 nm. This appropriate layer is helpful for improving the surface stability of LMNC and the diffusion of lithium, leading to an obvious enhancement of the electrochemical performance. Our result confirmed that the average discharge specific capacities for LV-3 sample at 0.1 C, 0.2 C, 0.5 C, 1 C, and 3 C are respectively 265.9, 219.1, 188.0, 156.3, and 121.5 mAh g−1, which are much larger than the values of other samples. After 50 cycles at a 1 C rate, the capacity retentions for different samples are 60.7%, 74.0%, 87.6%, and 70.4%, indicating that LV-3 sample exhibits the best performance. Furthermore, EIS measurements showed that the diffusion coefficient for LV-3 sample is calculated to be 1.26 × 10−15 cm2 s−1, which is also the largest value among all considered samples. Our experiments identified that coating an ionic conductive layer on the cathode material surface will significantly improve their rate capacity and cycling stability. [ABSTRACT FROM AUTHOR]

Abstract Co-doped CeO 2 (Ba 0.10 Ga 0.10 Ce 0.80 O 3–δ) was synthesized via a cost-effective co-precipitation technique, and the electrochemical properties of the solid oxide fuel cell were studied. The microstructural and surface morphological properties were investigated by XRD and SEM, respectively. The structure of the prepared material was found to be cubic fluorite with an average crystallite size of 36 nm. The ionic conductivity of the prepared BGC (Ba 0.10 Ga 0.10 Ce 0.80 O 3–δ) electrolyte material was measured as 0.071 S cm−1. The activation energy was found to be 0.46 eV using an Arrhenius plot. The maximum power density and current density achieved were 375 mW cm−2 and 893 mA cm−2, respectively, at 650 °C with hydrogen as a fuel. This study shows that the prepared co-doped electrolyte material could be used as a potential electrolyte to lower the operating temperature of solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

In recent years, ion conductive hydrogels based on photocurable 3D printing technology have attracted wide attention in the application of wearable sensors, which greatly simplifies the manufacturing process of devices, while making devices with high sensitivity and high fidelity. However, the current ionic hydrogel network via photocuring 3D printing is mainly crosslinked by covalent bonds. Due to the lack of sufficient energy dissipation and high-functionality cross-links within the network, the gel will inevitably crack after continuous dynamic loading. Here, we designed an organic gel with excellent tear resistance, which is mainly attributed to the high-functionality cross-links constructed by nano-clay containing a large number of hydroxyl groups. Specifically, the precursor of the organic gel is mainly composed of N-methylol acrylamide (NAM), nano-clays, photoinitiator, and water-glycerol binary solvent system. After photocurable printing, lots of hydrogen bonds are formed between nano-clays and poly-NAM network, which not only provides an energy dissipation mechanism for the gel network, but also acts as a nanoscale cross-linking site to resist crack propagation during the stretching of the gel. Under the action of nano-clay, the tear resistance of the gel has been greatly improved. In addition, the sodium ions released by the nano-clay ensure the good ionic conductivity of the gel, verifying its potential as a strain sensor with high sensitivity. What's more, combining skin-like organic gels and 3D printing technology enables the manufacture of highly sensitive sensors much easier and more designable. This study not only provides a method for the preparation of high-precision ionic conductors with excellent tear resistance, but also clears the way for developing a new class of wearable devices and intelligent electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Increased availability of methane from shale gas and stranded gas deposits in the recent years may facilitate the production of ethylene by means of potentially more competitive routes than the state-of-the-art steam cracking processes. One appealing route is the oxidative coupling of methane (OCM), which is considered in this work for the production of ethylene by means of the use of catalytic membrane reactors (CMR) based on Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) ceramic material. In a first approach, a screening of 15 formulations as catalysts for the ethylene-ethane production was conducted on CMR consisting of disk-shaped planar BSCF membranes. At 900°C, the maximum C2 selectivity was 70%, reached with Ba0.5Sr0.5FeO3−δ and La0.5Ce0.1Sr0.4Co0.8Fe0.2O3−δ catalysts. On the other hand, low CH4 conversions (XCH4) resulted in C2 yields below 3%. Operation at 1,000°C significantly shifted XCH4 for all the activated membranes due to the decrease in CH4/O2 ratios, thus obtaining C2 yields close to 9% and productivities of ca. 1.2 ml·min−1·cm−2 with Ce0.9Gd0.1O2−δ and Ba0.5Sr0.5Co0.8Fe0.2O3−δ impregnated with Mn-Na2WO4 catalysts. The performance of OCM reaction was also studied in a tubular catalytic membrane reactor. Tubular configuration improved C2 yield by minimizing CH4/O2 ratios up to 1.7, obtaining a maximum of 15.6% at 900°C with a BSCF capillary membrane activated with a packed bed of 2 wt% Mn/5 wt% Na2WO4 on SiO2 catalyst.

The viability of water gas shift catalytic system for mobile application passes through obligatory reactor volume reduction, achieved normally by using less charge of more efficient catalyst. Completely new concept for catalyst design is proposed: a catalytic system including classically reported WGS catalysts of different nature or active phase (Cu, Pt or Au) mechanically mixed with an ionic conductor. The influence of the later on catalyst activity is studied and discussed, more precisely its effect on the rate of the reaction-limiting step and catalysts’ efficiency. It is demonstrated with this study, that the presence of an ionic conductor in contact with a WGS catalyst is essential for the water supply (dissociation and transport), thereby potentiating the water activation step, whatever the mechanism and catalyst overall performance. [ABSTRACT FROM AUTHOR]

The Li content and anion lattice of Li 4 SiO 4 were modified to improve ionic conductivity. Li 2 CO 3 and Si 3 N 4 were mixed in a ratio of Li/Si = 4.5 and heated in NH 3 at 820 °C, which resulted in the formation of the oxynitride, Li 4.1 SiO 3.9 N 0.1 . Powder X-ray diffraction analyses revealed Li 4.1 SiO 3.9 N 0.1 and Li 4 SiO 4 to be isostructural with a subtle variation in the lattice constants. Diffuse-reflectance absorption spectroscopy, however, showed a significant decrease in the band gap, from 5.6 eV in Li 4 SiO 4 to 4.8 eV in Li 4.1 SiO 3.9 N 0.1 . X-ray photoelectron spectra of the Li 1 s and Si 2 p levels revealed enhanced lattice covalency in Li 4.1 SiO 3.9 N 0.1 compared to the oxide phase. The ionic conductivity of Li 4 SiO 4 and Li 4.1 SiO 3.9 N 0.1 were measured by ac impedance spectroscopy over the temperature range 100–400 °C. Non-linear fitting analysis of the equivalent circuit revealed that the ionic conductivity of Li 4.1 SiO 3.9 N 0.1 was approximately one order of magnitude higher than that of Li 4 SiO 4 . [ABSTRACT FROM AUTHOR]

Ba 3 MoNbO 8.5 compound has been recently discovered as novel oxide ionic conductor with a structure that is a hybrid between 9R hexagonal perovskite and palmierite. In this work, the full substitution of Mo with W has been demonstrated as possible, without altering significantly the conductivity of the material. The crystal structure of the Ba 3 Mo 1 − x W x NbO 8.5 solid solution (with x equals 0, 0.25, 0.5, 0.75 and 1) has been investigated by X-ray powder diffraction, showing a reduction of the unit cell by increasing the molybdenum content, despite the larger size of tungsten compared to molybdenum. Neutron powder diffraction measurements have been performed, indicating different levels of contribution of 9R polytype and of palmierite to the hybrid structure of the material as a function of the W-content. [ABSTRACT FROM AUTHOR]

The lithiation of tungsten bronze oxide β-SrTa 2 O 6 was accomplished by the solid state ion exchange of Sr 2+ → 2Li + , which led to a solid solution of Li x Sr 1−0.5 x Ta 2 O 6 ( x = 0–0.31). For the above conversion, β-SrTa 2 O 6 was reacted with various amounts of Li 2 CO 3 at 600 °C in air. With increasing x in Li x Sr 1−0.5 x Ta 2 O 6 , an orthorhombic-to-tetragonal symmetry transition was observed along with a gradual decrease in lattice volume. As observed from scanning electron microscopy and transmission electron microscopy, the grains of Li x Sr 1−0.5 x Ta 2 O 6 phases with x = 0.17 and 0.25 were formed from columnar bundles aligned along the c -axis. Solid state 7 Li nuclear magnetic resonance (NMR) spectroscopy revealed the presence of two different Li environments in Li x Sr 1−0.5 x Ta 2 O 6 , and their respective populations. The ionic conductivity of Li x Sr 1−0.5 x Ta 2 O 6 was measured by ac impedance spectroscopy as functions of the temperature and composition x . Regardless of the composition, the conductivity of Li x Sr 1−0.5 x Ta 2 O 6 displayed an Arrhenius type temperature dependence, and the highest Li + conductivity was found from x ≈ 0.17. At temperatures between 75 and 268 °C, the Li + ionic conductivity of Li 0.17 Sr 0.92 Ta 2 O 6 increased from 10 −8.8 S/cm to 10 −5.0 S/cm with an activation energy of 0.74 eV. [ABSTRACT FROM AUTHOR]

The 70-year history of scientific endeavor of solid state ionics research in Japan is reviewed to show the contribution of Japanese scientists to the basic science of solid state ionics and its applications. The term 'solid state ionics' was defined by Takehiko Takahashi of Nagoya University, Japan: it refers to ions in solids, especially solids that exhibit high ionic conductivity at a fairly low temperature below their melting points. During the last few decades of exploration, many ion conducting solids have been discovered in Japan such as the copper-ion conductor Rb4Cu16I7Cl13, proton conductor SrCe1-xYxO3, oxide-ion conductor La0.9Sr0.9Ga0.9Mg0.1O3, and lithium-ion conductor Li10GeP2S12. Rb4Cu16I7Cl13 has a conductivity of 0.33 S cm-1 at 25 °C, which is the highest of all room temperature ion conductive solid electrolytes reported to date, and Li10GeP2S12 has a conductivity of 0.012 S cm-1 at 25 °C, which is the highest among lithium-ion conductors reported to date. Research on high-temperature proton conducting ceramics began in Japan. The history, the discovery of novel ionic conductors and the story behind them are summarized along with basic science and technology. [ABSTRACT FROM AUTHOR]

Lithium garnet-type oxides Li7−2 xLa3Zr2− xMo xO12 ( x=0, 0.1, 0.2, 0.3) ceramics were prepared by a sol-gel method. The influence of molybdenum on the structure, microstructure and conductivity of Li7La3Zr2O12 were investigated by X-ray diffraction, scanning electron microscopy, and impedance spectroscopy. The cubic phase Li7La3Zr2O12 has been stabilized by partial substitution of Mo for Zr at low temperature. The introduction of Mo ( x≥0.1) can accelerate densification. Li6.6La3Zr1.8Mo0.2O12 sintered at lower temperature 1100°C for 3 hours exhibits highest total ionic conductivity of 5.09 × 10−4 S/cm. Results indicate that the Mo doping LLZO synthesized by sol-gel method effectively lowers its sintering temperature and improves the ionic conductivity. [ABSTRACT FROM AUTHOR]

Lithium superionic conductors with the Li10GeP2S12 (LGPS)-type structure are promising materials for use as solid electrolytes in next-generation lithium batteries. A novel member of the LGPS family, Li9.42Si1.02P2.1S9.96O2.04, and its solid solutions were synthesised by quenching from 1273 K in the Li2S–P2S5–SiO2 pseudoternary system. The material exhibited an ionic conductivity as high as 3.2×10−4 S cm−1 at 298 K, as well as the high electrochemical stability to lithium metal, which was improved by the introduction of oxygen into the LGPS-type structure. An all-solid-state cell with a lithium metal anode and Li9.42Si1.02P2.1S9.96O2.04 as the separator showed excellent performance with a high coulomb efficiency of 100%. Thus, oxygen doping is an effective way of improving the electrochemical stability of LGPS-type structure.

In order to investigate why crystal symmetry lowers with increasing temperature by phase transition of TII–III (=369 K) in Cs3H(SeO4)2, in spite of the fact that crystal symmetry in the high-temperature phase of many ionic conductors becomes higher by the phase transition, we have studied the relation between the change in crystal symmetry and the appearance of proton motion. It was found from the analysis of domains based on crystal structure that the number of possible geometrical arrangement of hydrogen bond in phase II becomes two times larger than that in phase III, derived from the lowering of crystal symmetry with increasing temperature. These results indicate that the lowering of crystal symmetry in phase II appears by the increase of the number of geometrical arrangements and by the enhancement of the flexibility of hydrogen bond. Considering that the enhancement of the flexibility of hydrogen bond yields mobile proton in phase II, it is deduced that mobile proton in phase II appears in exchange for the lowering of crystal symmetry at II–III phase transition.

Bulk specimens of CeGdO prepared with powders within a range of specific surface area were sintered in oxidizing, inert, and reducing atmospheres. The aim of this work is to investigate the effects of the sintering atmosphere on the microstructure and grain and grain boundary conductivities of the solid electrolyte. The lattice parameter determined by Rietveld refinement is 0.5420(1) nm, and the microstrain was found negligible in the powder materials. Specimens sintered in the Ar/4 % H mixture display larger average grain sizes independent on the particle size of the starting powders. The grain and grain boundary conductivities of specimens sintered under reducing atmosphere are remarkably lower than those sintered under oxidizing and inert atmospheres. The activation energy (∼0.90 eV) for total electrical conductivity remains unchanged with both the initial particle size and the sintering atmosphere. [ABSTRACT FROM AUTHOR]

Beyond state-of-the-art lithium-ion battery (LIB) technology with metallic lithium anodes to replace conventional ion intercalation anode materials is highly desirable because of lithium's highest specific capacity (3,860 mA/g) and lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode). In this work, we report for the first time, to our knowledge, a 3D lithium-ion–conducting ceramic network based on garnet-type Li6.4La3Zr2Al0.2O12 (LLZO) lithium-ion conductor to provide continuous Li+ transfer channels in a polyethylene oxide (PEO)-based composite. This composite structure further provides structural reinforcement to enhance the mechanical properties of the polymer matrix. The flexible solid-state electrolyte composite membrane exhibited an ionic conductivity of 2.5 × 10−4 S/cm at room temperature. The membrane can effectively block dendrites in a symmetric Li j electrolyte j Li cell during repeated lithium stripping/plating at room temperature, with a current density of 0.2 mA/cm2 for around 500 h and a current density of 0.5 mA/cm2 for over 300 h. These results provide an all solid ion-conducting membrane that can be applied to flexible LIBs and other electrochemical energy storage systems, such as lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

In this work, we describe the preparation of YSZ layers on porous and non-porous substrates using the Pulsed Injection MOCVD technique for solid electrolyte applications. In this technique, the vapour phase is obtained by injecting micro-droplets of the desired solution delivered from a container kept at room temperature into a heated evaporator connected to a deposition chamber. The droplet characteristics, volume, precursor concentration and injection frequency will control and determine the thickness and the microstructure of the layers. The system offers a high degree of repeatability of the liquid volume injected and thus a high reproducibility of the layers from low to high growth rates. This process has been optimised in order to obtain dense YSZ membranes to be used as solid electrolytes in SOFC, oxygen generators and oxygen sensors. Future work will consist in the preparation of anode-electrolyte-cathode multilayered devices. For this purpose, experimental parameters have been studied and optimised in order to obtain thin YSZ membranes on dense and porous substrates.En este trabajo se presentan los resultados preliminares sobre películas delgadas de YSZ obtenidas mediante la nueva técnica de MOCVD de inyección pulsada para su aplicación como electrolitos sólidos. La originalidad de esta técnica consiste en la preparación e introducción de la fase vapor que se realiza mediante la inyección pulsada de micro-gotas de la solución líquida, que contiene los precursores de los elementos a depositar, dentro de la zona de reacción. Las características de la gota: tamaño, concentración de la solución y frecuencia de inyección determinan el espesor y la micro-estructura de las capas obtenidas. Este método, además de muy reproducible, permite obtener fácilmente estructuras multicapas con bajos ritmos de crecimiento para epitaxias o con altos ritmos de crecimiento para la obtención de heteroestructuras. Se ha puesto a punto esta técnica para la obtención de capas densas de YSZ (circona estabilizada con itria), material comúnmente utilizado como electrolito sólido de alta temperatura en sondas de oxígeno, generadores de oxígeno y SOFC (pilas de combustible de estado sólido). Se pretende obtener dichos dispositivos en forma de multicapas del tipo ánodo/electrolito/cátodo. Para ello, se han depositado capas de YSZ sobre silicio para optimizar los parámetros de depósito pero también sobre sustratos porosos activos que puedan actuar como electrodo en los dispositivos anteriormente descritos.

We present electrical conductivity measurements of BIFEVOX Bi4V2-xFexO11-y (0≤x≤0.9; 0≤y≤1), in which V (IV) ions have been systematically substituted by Fe (III) ions. Conductivity shows a power law frequency dependence described by the form σ*(ω)=σdc[1+(jω/ωp)n], known as universal dynamic response. Conversely, the electric modulus shows asymmetric peaks, characterized by stretched exponentials relaxation functions in time domain of the form φ(t)=exp(-(t/τσ)β). β is determined by the degree of correlation in the ionic motion. It´s value, β=0.56±0.03, is almost independent of temperature and iron content. Increasing Fe content leads to an exponential decrease of the conductivity and to an increase of the activation energy of the conduction process from 0.20 to 0.97 eV. These results are discussed in terms of oxygen vacancy ordering upon Fe (III) substitution.Presentamos medidas de la conductividad eléctrica del sistema BIFEVOX Bi4V2-xFexO11-y (0≤x≤0.9; 0≤y≤1), en el que se realiza la sustitución de iones V (IV) por Fe (III) de forma sistemática. La conductividad muestra un comportamiento potencial con la frecuencia, descrito por σ*(ω)=σdc[1+(jω/ωp)n], y conocido como respuesta dieléctrica universal. Análogamente, el módulo eléctrico presenta picos asimétricos, cuya función de relajación en el dominio del tiempo puede describirse mediante exponenciales “estiradas” de la forma φ(t)=exp(-(t/τσ)β). β da cuenta del grado de correlación del transporte iónico, siendo su valor, β=0.56±0.03, casi independiente de la temperatura y del contenido en Fe. Con el aumento en el contenido de Fe, la conductividad disminuye exponencialmente y la energía de activación del proceso de conducción aumenta de 0.20 a 0.97 eV. Estos resultados se discuten en términos de la ordenación de vacantes oxígeno al dopar con Fe (III).

Environmental transmission electron microscopy (ETEM) equipped with an aberration corrector was used to get further insights into the mechanism of soot oxidation on yttria-stabilized zirconia (YSZ), an O 2− ionic conductor. In situ observations, with a resolution of around 1 nm, of a “tight” YSZ/real soot mixture were performed at 550 °C in the presence of a few mbar of oxygen (2 and 3 mbar). Preliminary experiments were conducted to validate that moderate electron beam illumination conditions do not control the soot combustion. Video sequences recorded at 550 °C clearly confirmed that bulk YSZ oxygen atoms are the active species for soot oxidation at the soot/YSZ interface as no oxidation takes place without contact. The number of soot/YSZ contact points and their evolution with time are the key parameters for soot oxidation. The contact length between the soot and the YSZ grains could be estimated to be around 20–40 nm only. [ABSTRACT FROM AUTHOR]

We prepared the b -axis-oriented polycrystalline Na 0.85 Ti 0.51 Ga 4.37 O 8 (NTGO) embedded in Ga 2 O 3 -doped Na 2 Ti 4 O 9 matrix using the reactive diffusion technique. When the sandwich-type Ga 2 TiO 5 /NaGaO 2 /Ga 2 TiO 5 diffusion couple was heated at 1323 K for 24 h, the NTGO polycrystal was readily formed in the presence of a liquid phase. The resulting polycrystalline material was characterized by X-ray diffractometry, electron microscopy and impedance spectroscopy. We mechanically processed the annealed diffusion couple and obtained the thin-plate electrolyte consisting mostly of the grain-aligned NTGO polycrystal. The ionic conductivity ( σ ) of the electrolyte along the common b -axis direction steadily increased from 1.3×10 −4 to 7.3×10 −3 S/cm as the temperature increased from 573 to 1073 K. There was a slope change at ca. 792 K for the Arrhenius plot of σ ; the activation energies were 0.39 eV above this temperature and 0.57 eV below it. The NTGO showed the crystal structure (space group C 2/ m ) with substantial positional disordering of one of the two Ga sites. The Na + ions occupied ca. 43% of the Wyckoff position 4 i site, the deficiency of which would contribute to the relatively high ionic conductivity along the b -axis. The reactive diffusion could be widely applicable as the novel technique to the preparation of grain-aligned ceramics of multi-component systems. [ABSTRACT FROM AUTHOR]

Eight plastic crystals of the types NEtxMe(4 − x)BEt4 and NEtyPr(4 − y)BEt4 (x=0–4, y=1–3) were found in a new region of ionic plastic crystals. In this area, globular cations and anions are assembled by weak interactions. Based on the results of solid-state 1H and 13C nuclear magnetic resonance (NMR) measurements, it was revealed that the ions performed isotropic reorientations in the NEtxMe(4–x)BEt4 crystals (x=0–4). Additionally, X-ray diffraction (XRD) of these compounds was able to identify the CsCl-type cubic structure. In contrast, the XRD reflections of NEtyPr(4−y)BEt4 (y=1–3) could be successfully fitted by distorted cubic lattices (trigonal symmetry). The NMR line shapes observed in these compounds were explained by overall molecular motions with large amplitudes (pseudo-isotropic reorientations). Differential scanning calorimetry (DSC) spectra of NEtyPr(4 − y)BEt4 (y=1–3) showed a low entropy change (ΔSmp) of 6–8 J K−1 mol−1 at the melting point. Ionic diffusion was identified by electrical conductivity measurements of NEtxMe(4 − x)BEt4 and NEtyPr(4–y)BEt4 (x=0–4, y=1–3). In the case of NPr4BEt4 crystals, ionic diffusion was also detected, although complex powder patterns and large ΔSmp values were observed by XRD and DSC measurements, respectively. [ABSTRACT FROM AUTHOR]

As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells (ITSOFC), samarium-doped ceria (SDC)-LiNaSO nano-composites were synthesized by a sol-gel method and their properties were investigated. It was found that the content of LiNaSO strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of LiNaSO was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC-LiNaSO(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC-LiNaSO composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability. [ABSTRACT FROM AUTHOR]