Search

Finely dispersed (CeO2)0.95(Sm2O3)0.05, (CeO2)0.90(Sm2O3)0.10 and (CeO2)0.80(Sm2O3)0.20 mesoporous powders with a specific pore volume of 0.080–0.092 cm3/g and a specific surface of 50–83 m2/g are synthesized by the co-precipitation of cerium and samarium hydroxides from the corresponding nitrate solutions. The prepared powders are used to obtain ceramic nanomaterials with a fluorite-like cubic crystal lattice with a coherent scattering region (CSR) of about 65–69 nm (1300 °C). The study of physicochemical and electrophysical properties of the prepared ceramics revealed the obtained materials featuring an open porosity of 2–6% and a predominantly ionic type of electric conductivity (ion transport numbers ti = 0.85–0.73 in the temperature range 300–700 °C). The conductivity in solid solutions proceeds via a vacancy mechanism with σ700 °C= 3.3·10−2 S/cm. The synthesized ceramic materials are shown to be promising as solid oxide electrolytes in medium temperature fuel cells.

3D‐interconnected ceramic/polymer composite electrolytes offer promise to combine the benefits of both ceramic and polymer electrolytes. However, an in‐depth understanding of the role of the ceramic scaffold's architecture, and the associated polymer/ceramic interfaces on the electrochemical properties of such composite electrolytes is still incomplete. Here, these factors are systematically evaluated using an interconnected composite electrolyte with a tunable and well‐defined architecture. The ionic conductivity of the ceramic scaffold is strongly dependent on its porosity and tortuosity, as demonstrated experimentally and via theoretical modeling. The connectivity of the ceramic framework avoids the high interfacial impedance at the polymer/ceramic electrolyte interface within the composite. However, this work discovers that the interfacial impedance between the bulk composite and excess surface polymer layers of the composite membrane dominates the overall impedance, resulting in a 1–2 order drop of ionic conductivity compared to the ceramic scaffold. Despite the high impedance interfaces, an improved Li+ transference number is found compared to the neat polymer (0.29 vs 0.05), attributed to the ceramic phase's contributions toward ion transport. This leads to flatter overpotentials in lithium symmetric cell cycling. These results are expected to guide future research directions toward scalable manufacturing of composite electrolytes with optimized architecture and interfaces. [ABSTRACT FROM AUTHOR]

Ceramic electrolytes hold application prospects in all-solid-state lithium batteries (ASSLB). However, the ionic conductivity of ceramic electrolytes is limited by their large thickness and intrinsic resistance. To cope with this challenge, a two-dimensional (2D) vermiculite film has been successfully prepared by self-assembling expanded vermiculite nanosheets. The raw vermiculite mineral is first exfoliated to thin sheets of several atomic layers with about 1.2 nm interlayer channels by a thermal expansion and ionic exchanging treatment. Then, through vacuum filtration, the ion-exchanged expanded vermiculite (IEVMT) sheets can be assembled into thin films with a controllable thickness. Benefiting from the thin thickness and naturally lamellar framework, the as-prepared IEVMT thin film exhibits excellent ionic conductivity of 0.310 S·cm−1 at 600 °C with low excitation energy. In addition, the IEVMT thin film demonstrates good mechanical and thermal stability with a low coefficient of friction of 0.51 and a low thermal conductivity of 3.9 × 10−3 W·m−1·K−1. This reveals that reducing the thickness and utilizing the framework is effective in increasing the ionic conductivity and provides a promising stable and low-cost candidate for high-performance solid electrolytes. [ABSTRACT FROM AUTHOR]

Finely dispersed (CeO2)0.95(Sm2O3)0.05, (CeO2)0.90(Sm2O3)0.10 and (CeO2)0.80(Sm2O3)0.20 mesoporous powders with a specific pore volume of 0.080–0.092 cm3/g and a specific surface of 50–83 m2/g are synthesized by the co-precipitation of cerium and samarium hydroxides from the corresponding nitrate solutions. The prepared powders are used to obtain ceramic nanomaterials with a fluorite-like cubic crystal lattice with a coherent scattering region (CSR) of about 65–69 nm (1300 °C). The study of physicochemical and electrophysical properties of the prepared ceramics revealed the obtained materials featuring an open porosity of 2–6% and a predominantly ionic type of electric conductivity (ion transport numbers ti = 0.85–0.73 in the temperature range 300–700 °C). The conductivity in solid solutions proceeds via a vacancy mechanism with σ700 °C= 3.3·10−2 S/cm. The synthesized ceramic materials are shown to be promising as solid oxide electrolytes in medium temperature fuel cells. [ABSTRACT FROM AUTHOR]

Electrical currents that are locally concentrated due to spatially variable interface resistance at the lithium-metal–ceramic–electrolyte interface can lead to the nucleation of voids. The Gibbs free energy barrier to nucleation is derived in terms of the electrochemical driving force, which favors, and the interfacial energies, which oppose the development of an embryo, the first step in the formation of a void. Nucleation can be suppressed by low values of the area-specific resistance (ASR) of the cell, and by chemical design of the interface that produces a high value for the contact angle. It is proposed that void nucleation is the precursor to the formation of dendrites. [ABSTRACT FROM AUTHOR]

Series of Gd3+ and Mg2+ co-doped ceria (Ce0.8Gd0.2-xMgxO1.9-δ) powders were prepared by a sol-gel method and electrolyte ceramics were obtained by sintering at 1300 °C. Thermogravimetric and differential scanning calorimetry, X-ray diffraction, scanning electron microscope and electrochemical impedance spectroscopy were used for structural, morphology and electrical characterization of the prepared samples. Well crystalline cubic fluorite structured composite was confirmed after calcination at 700 °C and the electrolyte ceramics sintered at 1300 °C for 4 h was quite dense with uniform microstructure. The electrochemical analysis results displayed that the highest conductivity has the Ce0.8Gd0.14Mg0.06O1.87 compound, i.e. 0.0203 S/cm at 800 °C. Therefore, it was concluded that co-doping with Gd3+ and Mg2+ could enhance the electrical properties of the CeO2 based solid electrolytes.

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the state-of-charge of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the μm-scale, not accessible with other methods. [ABSTRACT FROM AUTHOR]

Currently, a variety of solid Li+ conductors are being discussed that could potentially serve as electrolytes in all-solid-state Li-ion batteries and batteries using metallic Li as the anode. Besides oxides, sulfides and thioposphates, and also halogenides, such as Li3YBr6, belong to the group of such promising materials. Here, we report on the mechanosynthesis of ternary, nanocrystalline (defect-rich) Li[InxLiy]Br4, which crystallizes with a spinel structure. We took advantage of a soft mechanochemical synthesis route that overcomes the limitations of classical solid-state routes, which usually require high temperatures to prepare the product. X-ray powder diffraction, combined with Rietveld analysis, was used to collect initial information about the crystal structure; it turned out that the lithium indium bromide prepared adopts cubic symmetry (Fd3¯m). The overall and electronic conductivity were examined via broadband conductivity spectroscopy and electrical polarization measurements. While electric modulus spectroscopy yielded information on long-range ion transport, 7Li nuclear magnetic resonance (NMR) spin-lattice relaxation measurements revealed rapid, localized ionic hopping processes in the ternary bromide. Finally, we studied the influence of thermal treatment on overall conductivity, as the indium bromide might find applications in cells that are operated at high temperatures (330 K and above).

Sintering of ceramic electrolytes (CE) is the most efficient way to obtain a dense, all ceramic solid-state battery with oxide-based materials. However, the high temperature required for this process leads to detrimental reactivity between CE and the active material. Crystalline ceramics are necessary for highly conductive oxide materials. Still, thermomechanical properties of glass-phase materials can be used to obtain a denser and more conductive CE. Glass-phase CE can be produced with Nasicon-type CE. Here, Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) glass is used as a model to investigate the formability, densification, and conduction properties upon crystallization. A complete study of the crystallization mechanism is first performed to fully understand how a high conductivity of 6.3 × 10 -5 S·cm -1 at 30 °C with 92% relative density is obtained at a sintering temperature of only 550 °C without pressure. This is approximately 200 °C below the usual sintering temperature of LAGP. X-ray diffraction is then used to calculate the amount of crystalline phase as a function of time. A combined study of reaction kinetics and conductivity evolution reveals an autocatalytic nucleation effect, which produces an early crystallization pathway. Density is studied to quantify the ability of the glass to flow during the crystallization process.

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the state-of-charge of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the µm-scale, not accessible with other methods.

The effect of Bi deficiency on the microstructure and the conductive properties of sodium bismuth titanates (NBTs) have been investigated experimentally. A series of NBTs samples with different Bi deficiencies ranging from 0 to 10 at% were prepared with conventional solid state reaction. X-ray diffraction (XRD), backscattering electron images (BSE), and energy dispersive spectroscopy (EDS) were applied to investigate the phase structure, phase stability, and phase compositions. The total electrical conductivity of NBTs was measured by 2-probe AC impedance as functions of Bi deficiency, temperature, and oxygen partial pressure. The contribution of sodium ion was discussed. The proton and oxygen ion transfer numbers were measured by the EMF method and a combined method of OCV and EIS, respectively. As-calcined powders were found primarily in perovskite structure ( R 3 c space group), while increasing amount of secondary phases with Bi deficiency were observed in the sintered pellets. It indicates the thermal history significantly affects the phase stability of NBTs. The electrical conductivity in NBTs was found P O2 independent and significant enhancement could be achieved in Bi-deficient NBTs. The influences of Mg doping on the electrical conductivity in the Bi-deficient NBTs were also examined and found different effects depending on the Bi deficiency. Discussions and experimental results on the contributions of different charge carriers in NBTs suggested the oxygen ion be the predominant contributor to the total electrical conductivity, which is in agreement with the literature findings. [ABSTRACT FROM AUTHOR]

Gd 2 O 3 and Lu 2 O 3 double-doped Bi 2 O 3 compounds were prepared by solid-state synthesis techniques. Eight micro crystalline samples were synthesized with compositions of (Bi 2 O 3 ) 1−x−y (Gd 2 O 3 ) x (Lu 2 O 3 ) y , where x = 0.05, 0.1 and y = 0.05, 0.1, 0.15, 0.2. The structure of the ceramic materials was characterized by X-ray powder diffraction (XRD) and Thermo Gravimetry/Differential Thermal Analysis (TG/DTA). The morphology of the materials of the system was displayed by Scanning Electron Microscope (SEM). Also, the electrical conductivity of the samples was determined by the DC four-point probe technique (4PPT) in air at temperatures ranging from room temperature to 1100 °C. It was observed that two samples, (Bi 2 O 3 ) 1−x−y (Gd 2 O 3 ) x (Lu 2 O 3 ) y x = 0.05–0.1, y = 0.05 have mixture phases including δ-phase before additional heat treatments, and that the phases of all of the samples changed to the stable fluorite type face centered cubic δ-Bi 2 O 3 phase which has a high conductivity property after electrical conductivity measurements. The DTA results also showed that all samples have δ-Bi 2 O 3 phases. The highest electrical conductivity was seen for the sample of the (Bi 2 O 3 ) 0.85 (Gd 2 O 3 ) 0.1 (Lu 2 O 3 ) 0.05 system as 9.20 × 10 −2 (ohm.cm) −1 at 650 °C. The lowest activation energy was also calculated for the sample of the (Bi 2 O 3 ) 0.8 (Gd 2 O 3 ) 0.1 (Lu 2 O 3 ) 0.1 system as 0.5104 eV. The results indicated that the stable δ-Bi 2 O 3 phase samples can be used as electrolyte materials in solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Research and development efforts on sodium-ion batteries are gaining momentum due to their potential to accommodate high energy density coupled with relatively lower cost in comparison with lithium-ion batteries. In order for the sodium-ion batteries to be commercially viable, high performance electrolytes with acceptable ambient temperature ionic conductivity and wider electrochemical stability windows are being developed. A bibliometric analysis of the publications on various types of Na + ion conducting electrolytes since 1990 shows a total of 200 + publications and reveals an exponential growth in the last few years, due to reasons that the sodium-ion systems promise great potential as the future large scale power sources for variety of applications. This review consolidates the status of liquid (non-aqueous, aqueous and ionic), polymer gel and solid (ceramics, glasses, and solid polymers) electrolytes and discusses their ionic conductivity, thermal characteristics, electrochemical stability and viscosity towards applications in sodium-ion batteries. Among various types available, the non-aqueous solvent based electrolyte is the most promising one in terms of ionic conductivity even though it is flammable. [ABSTRACT FROM AUTHOR]

All solid-state lithium batteries are constructed by using highly conducting Ta-doped Li 7 La 3 Zr 2 O 12 (LLZTO) as the solid electrolytes as well as the supports, coated with composite cathodes consisting of poly(vinylidene fluoride) (PVdF):LiTFSI, Ketjen Black, and carbon-coated LiFePO 4 on one side and attached with Li anode on the other side. At 60 °C, the batteries show the first discharge capacity of 150 mAh g −1 at 0.05 C and 93% capacity retention after 100 cycles. As the current density increases from 0.05 C to 1 C, the specific capacity decreases from 150 mAh g −1 to 100 mAh g −1 . Further elevated temperature up to 100 °C leads to further improved performance, i.e. 126 mAh g −1 at 1 C and 99% capacity retention after 100 cycles. This good performance can be attributed to the highly conducting ceramic electrolytes, the optimum electronic and ionic conducting networks in the composite cathodes, and closely contacted cathode/LLZTO interface. These results indicate that the present strategy is promising for development of high-performance solid-state Li-ion batteries operated at medium temperature. [ABSTRACT FROM AUTHOR]

The LiBaPO compound has been obtained by the conventional solid-state reaction and characterized by X-ray powder diffraction. The title material crystallizes in the monoclinic system with C2/c space group. Electrical properties of the compound have been studied using complex impedance spectroscopy in the frequency range 200 Hz-5 MHz and temperature range 589-724 K. Temperature dependence of the DC conductivity and modulus was found to obey the Arrhenius law. The obtained values of activation energy are different which confirms that transport in the titled compound is not due to a simple hopping mechanism. AC conductivity measured follows the power-law dependence σ ∼ ω typical for charge transport. Therefore, the experimental results are analyzed with various theoretical models. Temperature dependence of the power law exponent s strongly suggests that tunneling of large polarons is the dominant transport process. [ABSTRACT FROM AUTHOR]

A novel electrolyte based on Gd doped CaMoO 4 with scheelite structure has been investigated. X-ray diffraction results show that the single-phase scheelite structure can be formed at 900 °C. Electrochemical measurement results indicate that the addition of certain quantity Gd 2 O 3 (x = 0.5) can increase the conductivity of CaMoO 4 obviously. The total conductivity of Ca 0.5 Gd 0.5 MoO 4+δ can reach 0.017 S cm −1 at 800 °C. The spectra follow the Arrhenius law with two activation energy 1.636 eV for T < 873 K and 1.364 eV for T > 873 K. Overall, Gd doped CaMoO 4 composite material with scheelite structure directs a new strategy to design novel electrolyte for SOFCs applications. [ABSTRACT FROM AUTHOR]

High purity cerium oxide and yttrium oxide were used to form ceria-based solid solution (Ce1−xYxO2−δ, 0.05&les;x&les;0.4) via a conventional mixed-oxide method. All the samples used were aged at 1000 °C in air for 8 days. Crystal structure and microstructure were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ionic conductivity (i.e., grain interior (GI) grain boundary (GB) and total conductivities) in this system were systematically studied as a function of dopant content over the temperature range of 250–850 °C in air using an impedance spectroscopy. The lattice parameter decreased with increasing the Y content, but it did not obey Vegard''s law. The Y doping had no significant effect on densification behavior and final sintered density, but leading to a significant decrease in grain size as compared to the undoped ceria. The composition x≃0.1 had a maximum GI conductivity, while a maximum total conductivity was observed at x≃0.15. A significant high-temperature aging effect was also found for the samples with higher Y doping levels. ∼10% and ∼15% decreases in the GI and GB conductivities, respectively, were detected in the aged Ce0.7Y0.3O2−δ ceramic. [Copyright &y& Elsevier]

All-solid-state batteries (SSB) emerge as a promising candidate to exceed the performance of conventional lithium ion batteries (LIB) due to their improved energy density, durability and safety. However, very few reports have demonstrated a long-term stable cycling and safety of pouch SSB. Herein, solid state pouch cell with nominal capacity of 0.3 Ah is successfully developed employing current-collector-free thin Li metal anode, double-sided composite LiFePO 4 cathode, and garnet-rich composite solid electrolyte (CSE) containing a doping of Li 7 La 3 Zr 1.75 Nb 0.25 O 12 garnet in a ratio 1:1 relative to poly(ethylene oxide) (PEO) host polymer, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. All-solid-state Li/CSE/LiFePO 4 prototype pouch cells tested under 0.2C/0.5C protocol at 60°C exhibit long cycle life (>4,100 cycles) and excellent safety attributed to the improved electrochemical properties, thermal and mechanical stability of the garnet-rich CSE. To the best of our knowledge, this is the longest lifetime up to date reported for bulk Li metal SSB. These outstanding results may pave the way for industrial development of advanced Li metal SSB towards practical application. [Display omitted] [ABSTRACT FROM AUTHOR]

Polysulphide has proven to be an efficient electrolyte for QDSSC, but at the cost of corroding the counter electrode and degrading the sensitizer due to its high redox potential. In this view for the first time, we have used oxide nanoceramics as low cost, easily processable and highly porous solid-state electrolytes for QDSSCs. High residual porosity and formation of liquid phase nanodomains across grain boundaries have added advantages for adsorption and diffusion in these hole transport layer. Yttria stabilized zirconia and ceria co doped yttria stabilized zirconia are the two solid state electrolytes designed in place of polysulphide. Dopants namely Y3+ and Ce4+ in ZrO 2 induces defects, oxygen vacancies and band shifts resulting in good charge transport. The interfaces and charge transfer kinetics suggests, recombination resistance offered by these ceramics avoid the back electron transfers via the downward shift of valence band (VB) much closer to that of sensitizer and also act as barriers (or passivation layer) to effectively suppress electron recombinations, resulting in high stability and Voc of the device. Devices designed with these new HTLs show efficiencies on par with polysulphide; they are extremely stable for almost up to 60 days (in ambient conditions), while cells fabricated with polysulphide electrolyte tend to degrade the device within 5 days. Image 1 • Nanoceramics: low cost, easily processable and highly porous solid-state electrolytes for QDSSCs. • Formation of liquid phase nanodomains across grain boundaries allows better diffusion of electrolyte. • Ceramics act as barriers (or passivation layer) to suppress electron recombinations, resulting in high stability and Voc. [ABSTRACT FROM AUTHOR]

The widespread use of energy storage for commercial products and services have led to great advancements in the field of lithium-based battery research. In particular, solid state lithium batteries show great promise for future commercial use, as solid electrolytes safely allow for the use of lithium-metal anodes, which can significantly increase the total energy density. Of the solid electrolytes, inorganic glass-ceramics and Li-based garnet electrolytes have received much attention in the past few years due to the high ionic conductivity achieved compared to polymer-based electrolytes. This review covers recent work on novel glassy and crystalline electrolyte materials, with a particular focus on the use of solid-state nuclear magnetic resonance spectroscopy for structural characterization and transport measurements. [ABSTRACT FROM AUTHOR]

The development of solid electrolytes with the combination of high ionic conductivity, electrochemical stability, and resistance to Li dendrites continues to be a challenge. A promising approach is to create inorganic–organic composites, where multiple components provide the needed properties, but the high sintering temperature of materials such as ceramics precludes close integration or co‐sintering. Here, new ceramic–salt composite electrolytes that are cold sintered at 130 °C are demonstrated. As a model system, composites of Li1.5Al0.5Ge1.5(PO4)3 (LAGP) or Li1+x+yAlxTi2−xSiyP3−yO12 (LATP) with bis(trifluoromethanesulfonyl)imide (LiTFSI) salts are cold sintered. The resulting LAGP–LiTFSI and LATP–LiTFSI composites exhibit high relative densities of about 90% and ionic conductivities in excess of 10−4 S cm−1 at 20 °C, which are comparable with the values obtained from LAGP and LATP sintered above 800 °C. It is also demonstrated that cold sintered LAGP–LiTFSI is electrochemically stable in Li symmetric cells over 1800 h at 0.2 mAh cm−2. Cold sintering provides a new approach for bridging the gap in processing temperatures of different materials, thereby enabling high‐performance composites for electrochemical systems. [ABSTRACT FROM AUTHOR]