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The processes of lithium insertion into TiOF 2 and TiF 3 electrodes were studied using electrochemical impedance spectroscopy. The measurements were carried out at different degrees of lithiation during the first two charge/discharge cycles. Electrical equivalent circuits were proposed to model the resulting impedance spectra. They reflect the processes of Li+ migration through SEI, lithium ion insertion/extraction stages with the change of titanium oxidation degree and lithium ion diffusion in the material volume. A comparative evaluation of kinetic parameters of TiF 3 and TiOF 2 electrodes depending on the degree of lithiation was carried out for the first time. It is shown that the main process of SEI formation takes place at the first cycle. SEI has a lower impedance value on TiF 3 electrodes. The concentration dependence of the charge transfer resistance and diffusion coefficient for TiF 3 and TiOF 2 materials is observed: with increasing lithium content the interfacial charge transfer resistance decreases and the Li+ diffusion coefficient increases. The concentration dependences of these parameters for TiOF 2 electrodes are more pronounced. • The kinetic parameters of TiOF 2 and TiF 3 electrodes was investigated by EIS method. • There is a difference in the R SEI , charge transfer and D Li+ for TiF 3 and TiOF 2. • The electronic and ionic conductivity of compounds influence the kinetic parameters. [ABSTRACT FROM AUTHOR]

The main chain of the inorganic polymer polyphosphazene exhibits good alkaline stability, but its poor film-forming properties and excessive water uptake have led to its limited application in the field of anion exchange membranes. In this study, naphthol-substituted polyphosphazene anion exchange membranes demonstrate good film-forming properties and conductivity. When the degree of naphthol substitution reaches around 33%, the hydrophobic main chain and hydrophilic side chain can form a well-defined hydrophilic and hydrophobic phase separation structure. Its ionic conductivity can reach 59.1 mS cm−1 at 80 °C, with a swelling ratio of only 23.5%. Observation under atomic force microscopy reveals that this is due to the introduction of naphthol, which enhances the π-π stacking effect between the main chains, forming a more stable hydrophobic region. Furthermore, when exposed to 4 mol L−1 NaOH at 80 °C for 1000 h, the ionic conductivity of NapP2N-4 decreased by only 19%, and the elongation at break did not significantly decrease, reflecting its good alkaline stability. • Synthesized a multisubstituted polyphosphazene anion exchange membrane. • Quaternary ammonium polyphosphazenes with naphthol substitution have good phase separation structure. • Effectively enhancing polysubstituted polyphosphazenes with naphthol substituted groups. [ABSTRACT FROM AUTHOR]

The thermo-electrical properties of gadolinia-doped ceria (GDC) thin films play a vital role in solid oxide fuel cell (SOFC) applications. Nonetheless, the effects of temperature, dopant concentration, and thickness on thermal expansion, and ionic conduction remain ambiguous. In the present study, we propose an efficient theoretical approach to emphasize the roles of surface layers and surface vicinity (called next-surface layers) on the thermo-electrical properties of GDC thin films. Using statistical moment method, thermal expansion coefficient, and ionic conductivity are calculated as functions of temperature, dopant concentration, and thickness. The lattice strain and ionic disorder in the surface and next-surface layers cause an increase in thermal expansion coefficient and ionic conductivity of thin films. Compared with bulk GDC, the thermal expansion coefficient is slightly larger while the ionic conductivity is more than one to two orders of magnitude enhancement and exhibits the maximum value at the higher concentration. The ionic conductivity depends non-linearly on the dopant concentration and the maximum conductivity is shifted toward a higher value as the temperature increases. The enhancement in thermal expansion coefficient and ionic conductivity offers new opportunities for SOFC electrolytes whose efficiency can be effectively controlled by tailoring the thickness. The theoretical calculations are compared to measured results from experiments. • Thermo-electrical properties of GDC thin films are theoretically investigated. • Importance of lattice strain, ionic disorder in surface (vicinity) are emphasized. • Thermal expansion and ionic conductivity increase due to the thickness reduction. • Thermal expansion coefficient is a decreasing function of dopant concentration. • Maximum conductivity is shifted toward a higher value as temperature increases. [ABSTRACT FROM AUTHOR]

Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) NASICON(Na Super Ion Conductive)-type solid electrolyte is prepared using conventional wet ball-milling and dry 3D mixing techniques to investigate the influence of mixing technique on properties of LATP. The mixing techniques influence impurity formation of calcined LATP powder. Thus, sintering behavior of the calcined powders is also affected by the mixing technique, i.e. LiTiPO 5 formation is confirmed in the ball-milling samples and Li-ion conductive Li 4 P 2 O 7 is main impurity in the 3D mixing samples. The influence is not limited to impurity formation. Uniform grains are observed in the 3D mixing pellet, contrarily, non-uniform sintering occurs in the ball-milling sample. As a result, the 3D mixing pellets demonstrate higher Li-ion conductivity than the ball-mill samples. The dry 3D mixing technique, which can omit drying process, is promising for LATP preparation owing to simplification of preparation process and a formation of high Li-ion conductive LATP pellets. Also, this study clearly shows that the mixing techniques affect ionic conductivity of the sintered LATP significantly, emphasizing importance of mixing procedure in the solid-state reaction. • Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) solid electrolyte was prepared by dry 3D mixing. • Impurity formation was different between 3D mixing and conventional wet ball-milling. • Sintering behavior of LATP was also influenced by the mixing technique. • In 3D mixing, uniform grain growth was observed during the sintering. • 3D mixing LATP revealed higher conductivity than wet ball-milling LATP. [ABSTRACT FROM AUTHOR]

Solid-state lithium-metal batteries are one of the best candidates for next-generation energy storage devices. However, their applications are hindered by the low ionic conductivity at room temperature and the inadequate interfacial compatibility of solid-state electrolytes (SSEs). Hence, an organic/inorganic composite solid electrolyte (CSE) of Li 6.25 Ga 0.25 La 3 Zr 2 O 12 (LGLZO)/polyethylene oxide (PEO) films were constructed. It's found that the crystallinity of CSE is significantly reduced and the ionic conductivity is increased to 3.57 × 10−4 S cm−1 at room temperature, which is about 60 times higher than that of the pure PEO.And the interfacial impedance is 243.84 Ω cm2, electrochemical window of 5.1 V. The assembled Li symmetric battery has excellent cycling stability more than 1000 h at 0.15 mA cm−2. The Li/PEO-LiTFSI-60 wt% LGLZO/LiFePO 4 (LFP) all solid-state lithium batteries (ASSLBs) also delivers superior electrochemical performances. This work can provide a reference for the development and real-world implementation of ASSLBs at room temperature. [Display omitted] • The relationship between filler content and sample properties was investigated by modulating the amount of LGLZO. • The ionic conductivity of LGLZO/PEO electrolyte was increased to 3.57×10-4 S cm-1, which is 60 times that of PEO. The ionof LGLZO/PEO electrolyte was increased to 3.57×10−4 S cm−1, which is 60 times that of PEO. • The CCD of Li|PEO/LGLZO|Li reached 0.8 mA cm−2, and it could cycle for over 1000 hours at current density of 0.15 mA cm−2. • Li|PEO/LGLZO|LFP has discharge specific capacity of 135 mAh g-1 and capacity retention rate of 97.26% after 80 cycles. [ABSTRACT FROM AUTHOR]

Recently, there has been strong interest in inorganic solid-state electrolytes for all-solid-state batteries, among which the garnet electrolyte LLZO has attracted much attention due to its excellent properties, such as high ionic conductivity and broad electrochemical stability. The aim of our study was to improve the performance of Ta-doped LLZO (LLZTO) by co-doping Ga and Y at the Li and La sites using conventional solid-phase synthesis methods. We thoroughly investigated how Ga and Y affect the microstructure and electrochemical properties of LLZTO. The results show that the relative density of Ga- and Y-doped LLZTO increases significantly up to 94% under the same sintering conditions. This doping resulted in a significant increase in ionic conductivity from 2.0 × 10−4 S·cm−1 to 1.05 × 10−3 S·cm−1 and a decrease in electronic conductivity from 2.16 × 10−7 S·cm−1 to 9.18 × 10−8 S·cm−1. Subsequently, the symmetric cells were assembled and tested, and it was found that the interfaces of the doped solid-state electrolytes were much more stable and that the cycling time was longer. Thus, our study successfully coordinated the co-doping of Ga, Y, and Ta, providing valuable insights for the subsequent production of LLZO materials with higher densities and better performance. This study is a promising step toward the realization of safer all-solid-state batteries with higher energy densities. • Innovative further doping of two elements on top of LLZTO solid electrolyte, harmonizing the doping of three elements. • An order of magnitude increases in ionic conductivity of LLZTO solid state electrolytes after doping. • The doped LLZTO solid state electrolyte has better suitability with lithium metal anode. [ABSTRACT FROM AUTHOR]

Over the last decade, anti-perovskites have drawn significant attention as potential solid-electrolytes for solid-state batteries. Due to the increase in consumption of lithium, there has been a push towards next generation batteries, including sodium-ion batteries. The first representative of the material class of sulphate hydride anti-perovskites, Na 3 SO 4 H, was synthesized by solid-state methods as a possible electrolyte for sodium solid-state batteries. Structural characterization confirms the results reported in literature with P 4/ nmm space group Thermal measurements (DSC and TGA) reveal the stability of the material up to 633 K with H 2 release beginning shortly after. Here were report the first electrochemical measurements of this new sulphate hydride anti-perovskite with room temperature conductivity of 4.0 × 10−7 S/cm. Similarly, the electronic conductivity was also measured by Direct Current (DC) experiments to understand a non-linear Arrhenius plot of the conductivity. From the EIS and DC measurements, it is suggested that the electronic and ionic conductivities of this material fall in the same range at room temperature. Upon heating, the material becomes a mainly ionic conductor, explaining the change in the activation energy values in the Arrhenius plot (0.83 eV at low T and 0.24 eV at high T). Solid-state NMR hints at defects in the structure that correspond to Na1 and Hb-c-d dynamics. • Anti-Perovskite sulfate Hydride as Solid State electrolytes. • High temperature stability. • Moderate Na ionic conductivity at room Temperature. • Solid state NMR and EXSY revealed the presence of Na & H defects in the structure. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) have drawn a lot of interest due to their special qualities, which include high conductivity that is comparable to liquid electrolytes, excellent mechanical stability, and high flexibility. Using the solution casting approach, we have synthesized copper ion conducting gel polymer electrolyte (GPE) films made of polyvinyl alcohol (PVA) as the polymer host. An ionic salt, copper sulphate (CuSO 4), and a plasticizing solvent, PANI/ [BMIM] [BF 4 ] polyionic liquid, were employed. The structural, electrical, and electrochemical properties of the GPE films were carefully examined. The significant XRD crystalline peak decreased and disappeared upon the addition of PANI/[BMIM] [BF 4 ] polyionic liquid, suggesting that PIL is a useful plasticizer for the PVA/HPMC polymers. The conductivity of GPE films was determined by electrochemical impedance spectroscopy measurements. The sample containing 20% CuSO 4 salt has the highest room temperature conductivity (σ = 5.11 × 10−3 S/cm). The measurements of transference numbers show that ions are primarily responsible for the transport of these electrolytes. It seems that the working voltage range is high enough to be used as an electrolyte in batteries, based on the results of using linear sweep voltammetry (LSV) and cyclic voltammetry to evaluate the electrochemical stability of the GPE films. • PVA/HPMC/PANI/CuSO 4 gel polymer electrolytes were synthesized. • The complex formation has been confirmed by using XRD and FTIR studies. • The effect of polyionic liquid and CuSO 4 contributes to enhancing ionic conductivity. • The gel polymer electrolyte exhibits a wide electrochemical window. [ABSTRACT FROM AUTHOR]

We combine 7Li NMR relaxometry and diffusometry with electrochemical impedance spectroscopy to unravel the mechanisms for the dynamics and transport of lithium ions in the lithium-deficient and halide-rich argyrodite Li 5.5 PS 4.5 Cl 1.5. In particular, we determine the effects of heat treatment on the cooperativity, heterogeneity, and subdiffusion of lithium ion motion. We find that heat treatment results in an enhancement of the dc conductivity by a factor of six to a high room-temperature value of σ dc = 14.9 mScm−1, whereas the change of the 7Li NMR self-diffusion coefficients D is considerably smaller. Accordingly, heat-treated Li 5.5 PS 4.5 Cl 1.5 shows a very small Haven ration of H R = 0.13 indicative of a high cooperativity of lithium ion dynamics. Moreover, after heat treatment, the collective correlation factor f I becomes very small, which is related to a strongly reduced relevance of subdiffusive lithium ion dynamics. However, heat treatment does not affect the activation energies, which are in the range E a = 0.34 − 0.40 eV for the dc conductivity σ dc , the diffusion coefficient D and also for the jump correlation time τ. 7Li NMR field-cycling relaxometry allows for a characterization of the lithium ion jumps based on a frequency-dependent dynamical susceptibility. We find that the susceptibility peak has a strongly asymmetric shape with a hardly broadened low-frequency flank and a strongly broadened high-frequency flank, reflecting a characteristic heterogeneity of the lithium ion dynamics, which derives from the specific cage-like arrangement of the lithium sites and the resulting difference in the rates of intra-cage and inter-cage jumps. Considering further the anion disorder in the crystal lattice, we propose that heat treatment facilitates cooperative inter-cage jumps, suppressing localized subdiffusive motion and enabling long-range ion transport along percolating pathways. • Combine 7Li NMR and EIS to determine the mechanisms for lithium ion dynamics and transport in lithium argyrodites • Combine 7Li NMR field-cycling relaxometry and field-gradient diffusometry to relate short-range and long-range ion dynamics • Compare self-diffusion coefficients and dc conductivity to study cooperative ion dynamics and determine the Haven ratio • Frequency-dependent electric conductivity and a collective correlation factor indicate minor relevance of subdiffusive motion • Field-cycling relaxometry reveals dynamical heterogeneity related to intra-cage and inter-cage jumps in the crystal structure [ABSTRACT FROM AUTHOR]

In this study, A-site defective Ca y Ti 0.93 Sc 0.07 O 3-α oxides were prepared to examine their ionic conduction properties. The electrical conductivities of two typical compositions were measured as functions of oxygen partial pressure P O2 , temperature, and humidity. Additionally, phase transition, chemical expansion, and CO 2 tolerance were examined in Ca 0.985 Ti 0.93 Sc 0.07 O 3-α using an atmosphere-controlled high-temperature X-ray diffraction. In Ca 0.947 Ti 0.93 Sc 0.07 O 3-α , the ionic conduction domain over a wide range of P O2 was observed at 500–800 °C, even though the humidity dependence of conductivities was confirmed only at 500 °C. Conversely, in Ca 0.985 Ti 0.93 Sc 0.07 O 3-α , the conductivities were enhanced in humidified atmospheres at 500–800 °C, while the ionic conductivities in dry atmospheres were higher than those of 8YSZ. As protonic and oxide ionic conductivities are comparable, the proton-oxide ion mixed conduction can be considered to occur in Ca 0.985 Ti 0.93 Sc 0.07 O 3-α. Therefore, a small percentage of Ca defect in Ca y Ti 0.93 Sc 0.07 O 3-α affects not only conductivity but also conductive ionic species. Furthermore, Ca 0.985 Ti 0.93 Sc 0.07 O 3-α did not show any phase transition and chemical expansion with hydration up to 900 °C. The crystal phase of Ca 0.985 Ti 0.93 Sc 0.07 O 3-α during the CO 2 tolerance test was observed to be stable. Therefore, the material properties of Ca y Ti 0.93 Sc 0.07 O 3-α suggest its high potential as electrolytes in high temperature electrochemical devices. • Ionic conductivities of A-site defective Ca y Ti 0.93 Sc 0.07 O 3-α oxides were studied. • Ca defect affects not only conductivity but also conductive ion species. • Ca 0.985 Ti 0.93 Sc 0.07 O 3-α has proton - oxide ion mixed conduction properties. • No phase transition and chemical expansion with hydration up to 900 °C. • The crystal phase during CO 2 tolerance test in this study was also stable. [ABSTRACT FROM AUTHOR]

The stability and selectivity (balance between ionic conductivity and vanadium permeability) of the ion exchange membrane in vanadium redox flow batteries (VRFB) are critical factors that directly impact the battery's performance and lifetime. Herein, we synthesized an ether-free polybenzimidazole copolymer (mcPBI) with rigid benzene ring and flexible alicyclic structures in the polymer's backbone via solution condensation from 3,3′-diaminobenzidine, isophthalic acid and 1,4-cyclohexanedicarboxylic acid monomers. A series of sulfonated polybenzimidazoles (mcPBI-S-x) with long side chains and different grafting degrees were synthesized through grafting reactions, and membranes were prepared by the solution casting method. Microphase separation structure created by grafting accelerates ion transport. Protonated imidazole in an acidic environment enhances proton transport while impeding vanadium penetration due to the Donnan effect. Additionally, the ionic cross-linking between the sulfonic acid group and the imidazole group is in favor of dimensional stability maintenance. The ether-free polymer backbone is conducive to maintaining stability. The results show that all mcPBI-S-x membranes exhibit excellent ion selectivity. Specifically, the mcPBI-S-32% membrane demonstrates optimal ion selectivity (9.06 × 107 S s cm−3), low area resistance of 0.45 Ω cm2, vanadium permeability (0.76 × 10−10 cm2 s−1) and swelling ratio in sulfuric acid (4.3%). The battery with the mcPBI-S-32% membrane demonstrates a coulomb efficiency of 90.50%, a voltage efficiency of 85.69%, and an energy efficiency of 77.55% at a current density of 60 mA cm−2. What's more, the membrane shows excellent chemical stability, and the chemical structure of mcPBI-S-32% characterized by 1H NMR does not change after 200 cycles at 120 mA cm−2. • Synthesis of an ether-free polybenzimidazole copolymer with alicyclic structure. • Proton exchange membrane containing sulfonated long-side-chain enable efficient proton transport. • High ion selectivity and low vanadium permeability are achieved. • VRFB shows improved efficiency and long-term cycling stability. [ABSTRACT FROM AUTHOR]

Due to plenty of potassium in the Earth's crust, potentially high energy density, high conductivity and fast ionic diffusion, potassium ion batteries (PIBs) are expected as promising and competitive alternatives to lithium-ion batteries (LIBs). However, in order to obtain high-performance potassium ion batteries, it is crucial to find suitable anode materials. Herein, from first principles methods based on DFT, we have investigated the possibility of a new two-dimensional material, penta-germagraphene (denoted as P-Ge 2 C 4) obtained by doping Ge atoms in penta-graphene, as anode materials for PIBs. The theoretical specific capacity is 554.8 mA h g−1. The intercalation potentials between 0.1 and 0.65 V are suitable for use in batteries. The metallic electronic structures of P-Ge 2 C 4 adsorbed K-ions and relatively small of diffusion energy barriers ensure good rate performance. The results show that two-Dimensional P-Ge 2 C 4 can be applied as an anode material for PIBs with good performance. • Two-dimensional P-Ge 2 C 4 can be applied as an anode material for PIBs with good performance. • The theoretical specific capacity is 554.8 mA h g−1. • The K-ion/K-vacancy migration energy barriers are relatively small. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO) is considered as the most promising and widely studies polymer matrix. However, its practical application is limited for its low ionic conductivity at room temperature. Here, a novel fluorinated branched (2,2,2-Trifluoroethyl methacrylate (TFEMA)) ether polymer (PFP) was synthesized through thiol-Michael addition click reaction and blended with PEO to obtained PEO-based polymer electrolyte. The introduction of PFP could reduce the crystallinity and hinder the migration of anions, resulting in a double increase in ionic conductivity and lithium-ion transference number. More importantly, the symmetric Li/Li employing blended polymer shows stable cycle more than 1700 h and the Li/LiFePO 4 cell shows the superior performance of both cycling and rating at 60 °C. Even at lower temperature (28 °C), the Li/LiFePO 4 cell exhibits encouraging cycling performance with 88.6% capacity retention at 0.2C after 100 cycles. This study provides a novel strategy for structural design and synthesis progress of solid polymer electrolyte. • PFP is synthesized by thiol-Michael addition click reaction, without any specialized energy required. • Branched structure reduced crystallinity of PEO and δ = 3.16 × 10−5 S cm−1 at 30 °C, which is an order of magnitude higher. • The polar groups in PFP optimal ionic conduction, resulting in the increase of lithium-ion transference number. • δ = 1.66 × 10−4 S cm−1 and t Li+ = 0.30 at 45 °C, which can benefit for the stable cycle of solid-state battery. [ABSTRACT FROM AUTHOR]

The La x Sr 1-x Co y Fe 1-y O 3-δ family of mixed conducting materials shows high electron- and oxygen ion conductivity, together with an appreciable catalytic activity for dissociation of ambient oxygen. These properties are of importance for solid oxide fuel cells. In this family of compounds, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF6428) has been well-studied, both fundamentally and in actual applications. The related composition, La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ (LSCF6482) has received much less attention despite its higher electronic and ionic conductivity. Literature results show for this composition sometimes rather conflicting results. The finegrained (100-150 nm) porous LSCF6482 electrodes show at higher temperatures a low-frequency dispersion, in the frequency range of ∼0.01–10 Hz. This dispersion is the result of gas phase diffusion limitation (GDL) coupled to the redox behavior of the mixed conducting LSCF6482. Applying a dense, thin layer of LSCF6482 between electrolyte and porous electrode improves the electrode properties, as it removes the 'bottle neck' for charge transfer of surface adsorbed oxygen moieties. Mixing Gd-doped cerium oxide, Ce 0.9 Gd 0.1 O 1.95 (CGO) with LSCF6482 in a porous electrode structure improves the electrode properties significantly as CGO has apparently a better catalytic activity for oxygen dissociation. The mid-frequency capacitance, C mid , is assigned to surface charge, i.e. adsorbed O ad − species. The introduction of CGO in the electrode appears to shift the dissociative adsorption of oxygen from the LSCF surface to the catalytically more active CGO surface. The significantly lower area specific resistance (ASR) is, however, strongly dominated by a larger GDL contribution at temperatures above ∼600 °C. • Deposition of porous LSCF and LSCF-CGO cathodes with and without dense interlayer • Show that the interlayer provides a direct path for the transfer of oxygen species. • Assign low frequency dispersion to GDL coupled with redox behavior of LSCF. • Assign mid frequency dispersion with LSCF-CGO to diffusion of surface adsorbed oxygen • Show a lower ASR up to 675 °C for LSCF-CGO cathodes than for LSCF ones [ABSTRACT FROM AUTHOR]

In this study, we synthesized co-doped Li 6.25 Al 0.25 La 3-y Nd y Zr 2 O 12 (LALNZO) solid-state electrolytes with varying Nd contents to investigate the influence Nd plays on phase evolution, microstructure, and lithium-ion conductivity. It was found that incorporating Nd ions into the lattice reduced bulk resistance by controlling Li+ concentration. However, X-ray diffraction analysis revealed that excessive Nd content led to the formation of Nd 2 O 3 , which negatively impacted ion transport and increased grain boundary resistance. It is noteworthy that the LALNZO (y = 0.2) ceramic exhibited outstanding performance, with 94% relative density, and ionic conductivity of 4.7 × 10−4 S/cm. The activation energy was 0.32 eV. Further, Li 6.25 Al 0.25 La 2.8 Nd 0.2 Zr 2 O 12 was able to demonstrate a stable capacity of 103 mA.h. g−1 after 50 cycles at a current density of 0.1C when used as an electrolyte in lithium-ion batteries. The findings of this study provide valuable insights for developing advanced solid-state electrolytes for lithium-ion batteries. [Display omitted] • Li 6.25 Al 0.25 La 3-y Nd y Zr 2 O 12 (y = 0–0.3) powder was successfully synthesized using the solid-state method. • The electrochemical performance of Li 6.25 Al 0.25 La 3 Zr 2 O 12 was optimized by addition of 0.2 mol Nd. • The excess Nd content lead to the formation of Nd 2 O 3 which can adversely affect ion transport. • The optimum electrolyte showed a capacity of 101 mA h g−1 after 50 cycles at 0.1C. [ABSTRACT FROM AUTHOR]

In this work, the influence of additives of rare earth and transition metals on the process of formation of the structure, mechanical and electrical properties of the SOFC electrolyte material based on zirconia was studied in order to identify the key technological and physical parameters affecting this process. A strong influence of the type of doping impurity on the lattice parameter of synthesized particles and sintered ceramics, on the strength and density of ceramics, and on the activation energy of ionic conductivity along grain boundaries was found. The effect of the type of additive on the value of ionic conductivity by grain volume in sintered ceramics was not detected. It was shown that the dopants effects on the ionic conductivity of zirconia electrolyte material in the indirect mode. The ionic radius of the dopants are determines the level of stability of the substitutional solid solution, and the diffusion of the impurity to the grain boundaries during sintering. It has been established that the more the ionic radius of the impurity differs from the equivalent ionic radius of the cation, the greater the activation energy of ionic conductivity along grain boundaries is observed. This depends on the degree of contamination of the grain boundaries with various impurities, which can diffuse to the grain boundaries and segregate there due to a violation of the Hume-Rothery rule. At the same time, the activation energy of ionic conductivity over the grain volume changes insignificantly, which indicates that the conductivity over the grain volume depends strongly on the number of oxygen vacancies, the concentration of which weakly depends on the ionic radius of the impurity. • Additional doping YSZ affects σ gb and does not affect σ g values of SOFC electrolyte • Ionic radius of the dopant does not directly affect the σ gb value • Ionic radius of the dopant determines the stability of the zirconia solid solution • Violation of the Hume-Rothery rule leads to segregation of dopant at grain boundaries • The more R i differs from R 0 the greater E A for ionic conduction at grain boundaries [ABSTRACT FROM AUTHOR]

This study focuses on an in-depth analysis of the relaxation phenomenon of sodium iodide (NaI)-complexed solid polymer electrolyte membranes based on sodium alginate (NaAlg) and poly (vinyl alcohol) (PVA) using various formalisms to test the suitability of these membranes for electrochemical device applications. The incorporation of NaI led to an increase in the ionic conductivity from (6.12 ± 0.14) × 10−8 Scm−1 (PNI0, pure blend) to (4.27 ± 0.09) × 10−6 (PNI10, 10 wt% of NaI). Deep insights into ion transport parameters at ambient and high temperatures, obtained from Nyquist plot fitting revealed the dependency of dc conductivity on carrier concentration (n) rather than mobility (μ) and diffusion coefficient (D). Scaling studies based on AC conductivity and tangent loss revealed the collapse of conductivity and tangent loss plots into a single master curve, implying that the optimum sample obeys time-temperature superposition principle (TTSP). The temperature dependence of the Jonscher's exponent indicates that the conduction mechanism can be effectively represented by the Quantum Mechanical Tunneling model (QMT). The non-Debye behavior exhibited by the samples can be elucidated through the electric modulus formalism and confirmed dielectric properties of the electrolytes, as demonstrated by the incomplete semicircular arcs observed in the Argand plots. Moreover, the prepared samples were completely biodegradable, indicating the eco-friendly nature of the electrolytes. [Display omitted] • SPE based on NaAlg-PVA complexed with NaI was developed. • Ion dynamics were systematically evaluated using various formalisms. • Jonscher's exponent suggests conduction via Quantum Mechanical Tunneling (QMT). • Scaling studies indicate a collapsed master curve, suggesting adherence to TTSP. • At ambient and high temperatures, n control SPE conductivity. [ABSTRACT FROM AUTHOR]

Solid-state electrolytes (SSEs) with excellent stability and flexibility have been used to overcome the safety and stability issues associated with the liquid electrolyte used in lithium-ion batteries (LIBs). In this study, thin composite solid electrolytes (CSEs) based on poly(vinylidenefluoride-cohexafluoropropylene) (PVDF-HFP) with high mechanical strength were fabricated. Garnet-type Li 6.5 Ga 0.2 La 2.95 Rb 0.05 Zr 2 O 12 (Ga-Rb LLZO) with high ionic conductivity was added to investigate the improvements in mechanical strength and ionic conductivity. The CSEs with Ga-Rb LLZO added to PVDF-HFP were referred to as PVDF-HFP + LLZO (PHL). Next, the interfacial resistance of the CSEs was reduced by adding a low-molecular-weight poly(ethylene glycol) (PEG) polymer, and the improvement in ionic conductivity and Li transfer was investigated. The CSEs with Ga-Rb LLZO and PEG added to the PVDF-HFP were referred to as PVDF-HFP + LLZO + PEG (PHLP). The ionic conductivity of the fabricated CSEs was 6.58 × 10−10 S cm−1 for the PVDF-HFP sheet, which increased to 1.10 × 10−5 S cm−1 and 2.33 × 10−4 S cm−1 for PHL and PHLP, respectively, at 70 °C. PHLP also had a very high lithium transference number of 0.789, and exhibited a discharge capacity of 123.16 mAh g−1 and a capacity retention rate of 88.29% after 200 cycles at 0.33C and 70 °C. • Addition of PEG reduces the crystallinity of PVDF-HFP. • Lithium transference number is high at 0.789. • The electrochemical stability window of PHLP has a value of 5.1 V vs Li/Li +. [ABSTRACT FROM AUTHOR]

The entire world is facing an alarming situation of energy demands and environmental pollution. Single-layer fuel cells are attractive in the era of renewable energy. Developing the materials for single-layer fuel cells (SLFC) is challenging to overcome the low electrical conductivity and polarization losses. In the present research work, novel nanocomposites materials Li 0.1 Ni 0.6 Zn 0.3 O 3-δ (LNZ) have been synthesized by solid-state techniques and Sm 0.2 Ce 0.8 O 2-δ (SDC) via co-precipitation route. Additionally, the effect of 20 wt% of single (Na), binary (Li: Na), and ternary (Li:Na:K) alkali carbonates on the performance of SDC composite material have been analyzed. All novel nanocomposites LNZ + SDC, LNZ + N-SDC, LNZ + LN-SDC, and LNZ + LNK-SDC were milled with 60:40 ratios respectively. Composite material based on 60 wt% LNZ and 40 wt% LN-SDC showed maximum mixed electronic and ionic conductivity of 2.29 Scm−1 at 600 °C with power density of 435mWcm−2. The structural and morphological proprieties of prepared nanocomposite materials were studied using X-Ray diffraction and Scanning electron microscopy respectively. The average crystallite size of 34 nm was observed with LNZ + LN-SDC composite material. The conductivity measurements were done using four-probe techniques and results showed the immense potential of prepared materials for SLFC application. • Alkali carbonated has been developed for one component electrolyte-free fuel cell. • Crystallite size was found to be <100 nm. • The mix conductivity was achieved 2.29 Scm−1 for LNZ + LN-SDC. • The maximum power density was obtained 435 mWcm−2 for LNZ + LN-SDC. [ABSTRACT FROM AUTHOR]

Transitioning to all-solid-state batteries and alternative technologies from liquid electrolyte counterparts is a matter of security and sustainability. In this scenario, magnesium is a strong candidate to replace lithium as a charge carrier because of its vast abundance, higher energy density, and suitability to be loaded in solid-state electrolytes, making batteries safer. This contribution reports a new solid electrolyte based on ZIF-8 modifications to improve its ionic conductivity. That material was obtained by the precipitation method and characterized through various spectroscopic and microscopic approaches. The ZIF-8 was modified by partially substituting the metal center, partially replacing Zn(II) with Cu(II), or the organic ligand, changing a fraction of 2-Methylimidazole with 2-Methylbenzimidazole. The impact of these modifications on the pristine ZIF-8 performance as an ionic conductor is tested through electrochemical impedance spectroscopy measurements, achieving a promising room-temperature ionic conductivity of 1 μS/cm. This work represents an effort to find a solid electrolyte synthesized under mild conditions with high conductivity to build a functional magnesium-ion battery prototype. Transport of Mg2+ in functionalized Zn imidazole as a solid electrolyte for potential Mg2+- based batteries. That material was functionalized by replacing a fraction of Zn atoms with Cu(2+) atoms, and of methylimidazole by benzimidazole. [Display omitted] • Solid state electrolytes. • Mg ion-based battery. • Modified Zn methylimidazolate. • MOF-based solid electrolyte. • Mg ion mobility in modified ZIF-8. [ABSTRACT FROM AUTHOR]

Lithium-ion (Li-ion) batteries are continuously being developed to enhance safety and energy density. One promising approach involves combining high nickel cathode material (NCM811) with Gel Polymer Electrolyte (GPE). However, achieving compatibility between these components remains a challenge. In this study, we investigate the use of Ethyl difluoroacetate (DFEA) to enhance the mechanical stability, ionic conductivity, and heat-resisting of polyethylene glycol dimethacrylate (PEGDMA) based GPE, thereby improving battery performance. The modified GPE/DFEA exhibits a smoother surface, increased Young's modulus (2.2 GPa), and high ionic conductivity (7.10 mS cm−1). Additionally, it enables the in-situ formation of a LiF-rich interface film on the electrode/electrolyte surfaces. Moreover, the Li||Li symmetrical cell with GPE/DFEA demonstrates stable cycling for 500 h without dendrite growth. Furthermore, Li|Cu asymmetrical cells using GPE/DFEA achieve an average Coulombic efficiency (CE) of 99.0% over 200 cycles at 1 mA cm−2, compared to only 62.2% for liquid electrolyte (LE). Importantly, the GPE/DFEA allows for operation beyond the conventional voltage limit of 4.25 V, reaching 4.38 V. It is successfully implemented in an Ah-level NCM811/graphite pouch cell, resulting in an energy density of 250 Wh/kg and improved cycle stability at 45 °C compared to standard electrolytes. Moreover, the GPE/DFEA-based batteries exhibit enhanced safety performance under conditions such as needle puncture and overcharge. The developed GPE can meet the practical requirements for battery applications. [Display omitted] • The mechanical stability of Gel Polymer Electrolyte is improved by the in-situ lithium fluoride. • The in-situ LiF can significantly improve the stability of the SEI and CEI films. • The GPE/DFEA enhances the high-temperature, high-voltage, and rate performance of batteries. • The outstanding performance of Ah-level NCM811/graphite pouch cells is attributed to the GPE/DFEA. [ABSTRACT FROM AUTHOR]

A NASICON-type Li 1+x Al x Ti 2-x(PO 4) 3 (LATP) cold-sintered solid electrolyte is reported with a dense structure, as a possible alternative the commonly recognized liquid organic electrolytes. A low-temperature sintering technology (below 200 °C) with a sintering additive, aid of acid solvent and high pressure is originally developed for preparing the solid electrolyte. In addition, the setup has been designed using in operando impedance technique simultaneously, the Cold Sintering Process (CSP) is monitored in order to explore the mechanism are taking place during the densification. As a result, an ionic conductivity as high as 4.48·10−5 S·cm−1, with a relative density of ∼82% has been achieved for 2 wt% Bi 2 O 3 and 25 wt% 3 m acid acetic solution, LATP powder, and sintered under 700 MPa and at 150 °C, reaching the highest value in published peer-reviewed literature. The cold-sintered ceramics without post-annealing high temperature treatments present kinetics limitations due to intergranular regions. Therefore, this bottleneck must be studied and overcome to achieve higher ionic conductivities at low temperatures. [Display omitted] • Modification strategies of ceramic electrolytes sintering are focused on. • Cold Sintering Process method to sinter x-Bi2O3:LATP solid electrolyte. • Combination of 3 cornerstones: sintering aid, CSP and in operando impedance. [ABSTRACT FROM AUTHOR]

In this work, a comparative study of the conductive properties of the PEO-NaClO 4 :NZSP composite solid polymer electrolyte (SPE) films was carried out in a wide range of the NZSP filler content (5–250 wt%), and the "ceramics-in-polymer" and "polymer-in-ceramics" fields were studied. The optimal composition of EO:NaClO 4 with molar ratio is 10:1 to obtain SPE films with low crystallinity (12.2%) and high ionic conductivity (1.7·10−5 S·cm−1 at 30 °C) was determined. An additional reduction in crystallinity to 4.5% was achieved due to the introduction of NZSP filler. High ionic conductivity and low apparent activation energy were obtained with a content of NZSP filler of 25 wt% (σ = 3.56·10−5 S·cm−1 (30 °C) and E a = 0.118 eV) for "ceramics-in-polymer" and 150 wt% (σ = 2.74·10−5 S·cm−1 (30 °C) and E a = 0.116 eV) for "polymer-in-ceramics" fields. The Na+ ion transference number t Na+ was determined for PEO-NaClO 4 and PEO-NaClO 4 :NZSP composites. The introduction of NZSP filler increases t Na+ from 0.45 (EO:NaClO 4 = 10:1) to 0.55 (25 wt% of NZSP filler) and 0.77 (150 wt% of NZSP filler). The NVP||PEO-NaClO 4 :NZSP-150 wt%||Na half-cell was tested at 60 °C and the average charge-discharge capacity of ∼60 mAh·g−1 was achieved. [Display omitted] • The optimal composition of PEO:NaClO 4 SPE film with low crystallinity and high ionic conductivity was obtained. • A detailed study of the PEO-NaClO 4 :Na 3 Zr 2 Si 2 PO 12 composite SPE films was carried out. • The conductivity maximum was determined in both "ceramics-in-polymer" and "polymer-in-ceramics" fields. • Introduction of the Na 3 Zr 2 Si 2 PO 12 filler (150 wt%) increases Na+ ion transference number. [ABSTRACT FROM AUTHOR]

Polymer electrolytes have been gaining much attention in battery research and development due to their non-volatility, possibility to reduce decomposition at the electrodes, flexibility, and improved safety. Polyelectrolytes are polymer systems in which one of the conducting species (anion or cation) is chemically bonded to the polymer backbone. Here, we report a Nafion-based polyelectrolyte system (Nafion-Li) derived by ion-exchange of the proton in the sulfonic acid group (–SO 3 H) with Li to enable Li-ion conduction. To further enhance the electrochemical properties, a pyrrolidinium-based ionic liquid (IL) of high ionic conductivity and wide electrochemical stability window was incorporated in the polyelectrolyte as an active plasticizer. The ionic conductivity of the Nafion-Li polymer electrolyte increased from 10−7 S cm−1 to 10−4 S cm−1 with the addition of the IL electrolyte solution. Cyclic voltammetry measured in the voltage range of −0.4 V to 2 V shows a lithium deposition peak and a lithium stripping peak, confirming a reversible redox reaction in the prepared polymer electrolytes. Galvanostatic charge-discharge studies of the optimized polymer electrolytes were performed by assembling coin type half cells with LiFePO 4 as the cathode and lithium as the anode in the voltage range 2.5 to 4.2 V. The first charge and discharge capacity of the IL-added "Nafion-Li" polymer electrolyte were 160 and 152 mAh/g, respectively. In-situ impedance spectroscopy and cyclability of the assembled cells are also discussed. • Lithiated Nafion was synthesized using ion-exchange process to enable Li+ conductivity. • 0.2 m LiTFSI-BMPyTFSI played the dual role — active dopant and plasticizer. • Ionic conductivity of lithiated Nafion increased to 10−4 S cm−1 with 50 wt% IL. [ABSTRACT FROM AUTHOR]

All-solid-state lithium‑sulfur batteries (ASSLSBs) based on sulfur or lithium sulfide (Li 2 S) as cathodes are one of the most promising candidates for next-generation energy storage devices due to their high theoretical energy density and good safety features. However, despite the promising outlook, the practical application of ASSLSBs is impeded due to the electronically and ionically insulating nature of S and Li 2 S. Consequently, even with carbon and solid state electrolytes (SSEs) addition, the electron and lithium-ion cannot transport smoothly through the cathode. Therefore, it is imperative to establish and tune effective electron/ion transport paths in the composite cathode to achieve high performance. In the present study, electronically/ionically dual conductive active material Li 2 S-LiI-MoS 2 and high ionically conductive Li 6 PS 5 Cl SSE were coupled and modified to control ionic and electronic paths in Li 2 S-based cathode composite. The optimized composite cathode possessed an overall gravimetric capacity of 423 mAh g−1 at 0.5C and 308 mAh g−1 at 2C with respect to the total mass of the cathode. The corresponding ASSLSBs achieved distinctively high energy with acceptable power density. The in-depth analysis by X-ray computed tomography revealed the three-dimensional conductive pathway in the composite cathode. • The Li 2 S-LiI-MoS 2 coupling with Li 6 PS 5 Cl as composite cathode. • The cathode shows balanced electronic and ionic conductivity approaching 10−3 S cm−1. • The optimized composite cathode exhibits good overall capacity of 423 mAh g−1 at 0.5C and 308 mAh g−1 at 2C. • X-ray CT reveals the microstructure of the cathode, including tortuosity and contact area. [ABSTRACT FROM AUTHOR]

Manganese-based oxides are a promising cathode material for aqueous zinc ion batteries. However, structural change and irreversible dissolution of manganese in manganese-based oxides during charging and discharging lead to poor cycling stability, which hinders their large-scale application. Elemental doping is an effective way to regulate the bonding strength and crystal structure of the material. In this paper, YMO materials with nanorod-like structures have been obtained by a hydrothermal method. Y-element doping enhances the stability of the material and improves the electronic and ionic conductivity of the material. The YMO material exhibits excellent electrochemical performance as a cathode material for aqueous zinc ion batteries. The electrode exhibits a high reversible discharge specific capacity of 409.3 mAh g−1 at a current density of 0.1 A g−1, and the electrode capacity hardly decays after 100 charge/discharge cycles, meanwhile, the YMO electrode shows good initial cycling stability even at different charge/discharge current densities. In addition, the YMO electrodes showed long-term cycling stability, with a capacity retention rate of 95.1% after 2000 cycles at a current density of 1 A g−1. The excellent cycling stability of the electrode is mainly due to the improved structural stability of YMO, which is related to the stronger Y O bonds acting as anchors in the lattice structure of MnO 2. Meanwhile, the strong interaction between doped Y3+ and O2− promotes the storage of H+. Structurally stable electrode materials obtained by optimizing doping elements to modulate bonding energy is an effective way to improve the stability of manganese-based materials. • YMO materials have excellent structural stability due to the anchoring role of Y O bonds in the MnO 2. • YMO electrodes show good initial cycling stability at different current densities. • The strong interaction of Y O bonds in the material improves the ionic conductivity of the material. [ABSTRACT FROM AUTHOR]

The dissociation degree of lithium electrolyte salts greatly affects the performance of solid-state polymer electrolytes (SSPE) in solid-state lithium-metal batteries (SSLBs). The previous synthetic tactics are generally based on single dissociation of electrolyte salt, for example, solely tethering the anions or capturing lithium cations. Herein, we present a dual-dissociation strategy to synthesize SSPE by simultaneously dissociate both the anions and cations among electrolyte salts. This is achieved by integrating the oligomeric silsesquioxanes (POSS) nanoparticles with suitable aperture in a poly(propylene carbonate) (PPC) gel matrix, where the POSS filler with suitable aperture interacts with both the TFSI anions and Li+ cations of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. However, the Li+ cations are movable under an external electric field and can migrate between cathode and anode to achieve charge transportations. The room temperature ionic conductivity of SSPE filled with POSS nanoparticles was found to be superior to that of SSPE with SiO 2 fillers, with a conductivity value of 2.04 × 10−4 S cm−1 and a higher Li+ ion transfer number of 0.71. This improvement is attributed to the utilization of a dual-dissociation strategy of lithium salt. The theoretical computations with nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) manifest that the efficient dissociation of electrolyte salt is ascribed to the coordination effect of Li+ ions with four oxygen atoms among POSS cage as well as the tethering function of POSS filler for TFSI− anions. This work provides an innovative dual-dissociation strategy to synthesize SSPE, which would benefit the practical use of polymer electrolytes in solid-state lithium-metal batteries. • A novel dual-dissociation strategy was proposed for composite polymer electrolyte. • The coordination effect of four oxygen atoms on POSS cage can dissociate Li+ ion. • The POSS matrix can tether TFSI− anions of electrolyte salt. [ABSTRACT FROM AUTHOR]

NASICON-type electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO 4) 3 attracts great attention with its high grain conductivity and stable microstructure. In this work, the Li 1.4 Al 0.4 Ti (1.6-x) Zr x (PO 4) 3 solid-state electrolytes were synthetized. And the influences of ZrO 2 addition on microstructural evaluation and ionic conductivity of Li 1.4 Al 0.4 Ti (1.6-x) Zr x (PO 4) 3 were studied using powder X-ray diffraction, scanning electron microscopy and impedance spectroscopy. All synthetic samples adopted single phase LiTi 2 (PO 4) 3 with NASICON type structure. The highest ionic conductivity of 0.54 mS/cm and the minimum activation energy of 0.232 eV were achieved for x = 0.04 sample sintered at 850 °C. These results indicate that ZrO 2 added Li 1.4 Al 0.4 Ti 1.6 (PO 4) 3 ceramic has a potential application in solid electrolytes. • New Li 1.4 Al 0.4 Ti (1.6-x) Zr x (PO 4) 3 solid-state electrolytes were prepared. • The ceramic sample can be densified at 850 °C sintering. • The structural, microstructural evaluation and its conductive mechanism were discussed. • The highest ionic conductivity of 0.535 mS/cm was achieved for x = 0.04 sample [ABSTRACT FROM AUTHOR]

Li 7 La 3 Zr 2 O 12 (LLZO) has excellent electrochemical performance and chemical stability, and has a promising application in solid-state batteries. However, the ionic conductivity needs to be improved when comparing with liquid electrolytes. And doping is a common strategy to improve the ionic conductivity. In this paper, investigated the optimal doping conditions and calcination temperature for the synthesis of Li 7-3x-y Al x La 3 Zr 2-y M y O 12 (M = Ta,Nb;x = 0.2–0.3;y = 0–1) by high-temperature solid-phase method, and the effects of Al Ta and Al Nb co-doping modification on the crystal structure, morphology, densification, and electrical properties of LLZO. The results show that Ta and Nb doping between 0.4 and 0.8 can be synthesized garnet-type LLZO solid electrolytes with stable cubic phase. The calcination temperature and time of Al Ta co-doping is 950 °C and >8 h, Al Nb co-doping is 900 °C and >6 h. Among them, the electrolyte made of Al Nb co-doping is better than Al Ta co-doping in terms of morphology and densification, and the highest ionic conductivity of both of them can reach up to 8.483 × 10−4 S·cm−1 and 7.928 × 10−4 S·cm−1, respectively, and activation energies can reduce to 0.298 eV and 0.301 eV, which are a significant enhancement of the electrical properties. However, the oxides of Nb element are cheaper, and the calcination synthesis temperature is lower and the time is shorter. Therefore, the synthesis of Al Nb co-doped modified LLZO by high-temperature solid-phase method is a low-cost, low energy consumption and high performance industrial production routes. [ABSTRACT FROM AUTHOR]

The solid-state electrolyte β -PbSnF 4 has been reported to have the highest fluorine-ion conductivity at room temperature among four different structures of the monoclinic (α), orthorhombic (o), cubic (γ), and tetragonal (β) at steady state. Therefore, finding an effective way to prepare β -PbSnF 4 or to transform β -PbSnF 4 from other phases is a research hotspot in FIBs. In particular, the transition mechanisms between γ -PbSnF 4 and β -PbSnF 4 are still unclear in the reported literature because the influence of trace moisture is ignored in previous research, which always leads to controversial conclusions about the phase transition mechanism. Previous articles have reported that γ -PbSnF 4 can only be transformed into β -PbSnF 4 by aging at a high temperature above 100 °C. However, this work shows that the transition from γ -PbSnF 4 to β -PbSnF 4 can occur at room temperature. Moisture is the critical factor in inducing the phase transition from γ to β -PbSnF 4. The resulting β -PbSnF 4 has a high fluoride-ion conductivity of 8.1 × 10−4 S cm−1, while the solid electrolyte for an all-solid-state FIB with BiF 3 as the cathode and Sn as the anode has a maximum discharge capacity of 55.8 mAh g−1 at 120 °C. [Display omitted] • γ -PbSnF 4 can be converted into β -PbSnF 4 at room temperature. • The moisture can induce the phase translation. • A high fluoride ion conductivity of 8.1*10−4 S cm−1 is achieved. • The protons in the H 2 O can trigger the rearrangement of the F atoms. [ABSTRACT FROM AUTHOR]

The properties of the Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 glass-ceramics were modified by the partial substitution of P5+ by Si4+, and the synthesis process is optimized. The thermal behavior of the original Li 1.5+х Al 0.5 Ge 1.5 Si x P 3-x O 12 (0 ≤ x ≤ 0.5) glasses was investigated using differential scanning calorimetry (DSC), optical dilatometry and heating microscopy. The glass transition temperature (T g) decreases from 525 to 457 °C with increasing additive content from x = 0 to x = 0.5. Single-phase glass-ceramics with the NASICON-type structure were synthesized up to x = 1, which was confirmed by X-ray diffraction (XRD), Raman and energy-dispersive X-ray (EDX) mapping data. It has been shown that the SiO 2 addition has a beneficial effect on the electrical properties of glass-ceramics, crystallized at 700 and 750 °C. However, heat treatment at 820 °C leads to a smaller increase in conductivity. Therefore, Si-containing glass-ceramics should be produced at lower temperatures than pure LAGP, which is 750 °C and correlated with the thermal analysis results. The influence of the SiO 2 addition on the bulk and grain boundary conductivity of the Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 has been studied in detail. The Li 1.52 Al 0.5 Ge 1.5 Si 0.02 P 2.98 O 12 glass-ceramics has the highest total ionic conductivity of 4.55·10−4 S/cm at RT and negligible electronic conductivity of 7.5·10−10 S/cm, therefore can be considered as promising solid electrolytes for all-solid-state batteries. • Single phase glass-ceramics with compact microstructure in the Li 1.5+х Al 0.5 Ge 1.5 Si x P 3-x O 12 system was obtained. • The introduction of a small amount of SiO 2 additive has the positive effect on Li+ conductivity. • A conductivity value of 4.55·10−4 S/cm at 25 °C was achieved for Si-doped glass-ceramics. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are being aggressively pursued for potential use in energy storage systems due to the natural abundance and low cost of sodium. In the present investigation, structural, thermal and electrochemical properties of a ionic liquid based Na-ion conducting polymer-salt-IL electrolytes (IL-NCPEs) formed using co polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) salt along with IL; 1-butyl-1-methypyrrolidinium bis(trifluoromethanesulfonyl)imide ([BMPYr] [TFSI]) is being reported. The samples were characterized using ionic conductivity, transference number measurement, thermal & electrochemical studies as a function of wt% IL. Incorporated [BMPYr][TFSI]-IL in the NCPE (i.e., PVdF-HFP + 10 wt% NaTFSI) modifies the different physicochemical properties such as complex formation, thermal, transport and electrochemical properties. The ionic conductivity of prepared IL-NCPEs has been found to increase with increasing the content of [BMPYr][TFSI]-IL and reaches to a maximum value of ∼0.85 mS/cm (at 30 °C). Also, the temperature dependent ionic conductivity obeys Arrhenius type thermally activated behaviour. For the optimized [BMPYr][TFSI]-IL, compatibility of IL-NCPEs with Na-metal electrode, high total ionic transference number (t ionic ∼ 0.98), cationic transference number (t Na + ∼ 0.31) and wide electrochemical stability (ESW ∼ 4.0 V) have been obtained. The above obtained properties of the prepared IL-NCPEs are promising for application in Na-rechargeable battery. [Display omitted] • Optimized IL-NCPE#70 shows high ionic conductivity 0.85 mS/cm at RT. • High ionic (t ionic ∼ 0.98) and cationic (t Na + ∼ 0.31) transference number. • IL-NCPE#70 shows wide electrochemical window (∼4.2 V) • Symmetrical cell Na|IL-NCPE#70|Na show a stable cycling behaviour for over ∼210 h. [ABSTRACT FROM AUTHOR]

Using a combined approach based on the geometrical-topological (GT) analysis of crystal structures and bond valence site energy (BVSE) calculations, a high-throughput computer screening for 5339 compounds with composition Ba a X b O c and Sr d Y e O f was made. It was determined the 231 compounds with 1D (66 compounds), 2D (93 compounds) or 3D (72 compounds) migration maps for O2−ion conductivity as new potentials oxygen-ion solid electrolytes. Among 110 compounds with low energy barriers (<0.80 eV) 78 compounds have GII < 0.30. By means, quantum mechanical modeling within DFT-NEB approach for BaTi 2 O 5 crystal structure was determined migration energy barriers for O2−-diffusion and 1D migration map with energy activation 0.97 eV was established. • Oxygen-ion conductors, ToposPro, BVSE approach, DFT-NEB modeling, high-throughput screening [ABSTRACT FROM AUTHOR]

As a new type of clean and efficient energy storage device, lithium-ion batteries have been widely used in electronic products, electric vehicles, and other fields, and the accompanying safety issues are of increasing concern. Therefore, solid-state lithium-ion conductors have become a current research hotspot. This paper used graphene oxide material to design and prepare Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 solid electrolytes by the co-precipitation method and performed some relevant characterizations. The results showed that the addition of graphene oxide optimized the electrolyte structure improved the density of the powder, promoted grain growth, improved the transport path of lithium ions, and thus increased the total ionic conductivity. The optimal doping ratio was 0.5 wt%, and the total ionic conductivity reached the maximum of 2.42 × 10−4 S/cm. Compared to pure Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 , the ionic conductivity increased by 154% after using the graphene oxide. It is believed that larger grains, fewer grain boundaries, and denser microstructure resulted in a less distorted migration pathway for lithium ions. Under the influence of graphene oxide, Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 exhibited better air stability than pure Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 electrolyte. The electrolyte prepared in this study showed great application potential in all-solid-state batteries. • The pore size of calcined powder is reduced and more uniform. • Larger grains, fewer grain boundaries, and denser microstructure were achieved. • The total conductivity reached 2.42 × 10−4 S/cm at 0.5 wt%, increased by 154%. • The air stability of LATP+GO was improved. [ABSTRACT FROM AUTHOR]

Novel low-temperature proton conducting membranes are fabricated from commercial and low-cost cellulose acetate (CA). Rather than a normal modification procedure, sodium 4-styrene sulfonate groups (SSA) are grafted into cellulose acetate chains through a facile one-step free radical polymerization. The resulting CA@P(SSA) membranes with different monomer concentrations were characterized using advanced and relevant techniques such as FT-IR, TGA, and SEM. The grafting of side-chain groups was adjusted to maximise the physicochemical features of the fabricated membranes, such as ion exchange capacity, water and methanol absorption, and conductivity. By considering these features the optimized membrane (Corresponding to 1.5 wt% SSA) exhibits excellent thermal-oxidative stability and tensile strength (22.742 N) better than Nafion® 212 (16.153 N). In addition, the grafted membrane demonstrated lower methanol permeability (5.514 × 10 − 7 cm 2 / s) and enhanced ionic conductivity (4.77 × 10 − 3 S/cm) with membrane selectivity of 8.65 × 10 3 S. s / cm 3 with peak power density (24.6 mW/cm2). In addition, the optimized membrane showed increase in performance than pristine CA membrane. Thus, these results provide new, straightforward, high-performance and low-cost polyelectrolyte membrane with a significant potential for direct methanol fuel cell. [Display omitted] • Low-temperature proton conducting membranes from commercial cellulose acetate grafted with sodium 4-styrene sulfonate groups. • Grafted membranes exhibit excellent thermal-oxidative stability and tensile strength better than Nafion® 212. • Lower methanol permeability and enhanced ionic conductivity with membrane selectivity of was observed. • A peak power density of 24.6 mW/cm2 was demonstrated. • The optimized membrane showed increase in performance than pristine CA membrane. [ABSTRACT FROM AUTHOR]

Nanocomposites (n-C 4 H 9) 4 NBF 4 –nanodiamonds were prepared and investigated for the first time. Nanodiamonds (C ND) with a specific surface area of 300 ± 20 m2/g and grain size of 5.4 ± 0.3 nm was taken as heterogeneous additive. According to the results of X-ray diffraction and thermal analysis studies, at high fraction of C ND the salt transforms to the amorphous phase which is stabilized on the interfaces with the nanodiamonds particles. The thickness of the amorphous layer was estimated from the thermal analysis data as 3.5 nm. It was found that the dependence of conductivity on the C ND fraction has a maximum 1.2 × 10−3 S/cm at 150 °C for the composition 0.02(n-C 4 H 9) 4 NBF 4 –0.98C ND corresponding to the volume fraction of C ND of 0.34. The conductivity was estimated using a mixing equation taking into account the concentration of the amorphous interface phase calculated from thermal analysis data. Estimation shows that conductivity of the amorphous interface phase is >3 orders of magnitude higher than that of pure (n-C 4 H 9) 4 NBF 4. • A comprehensive study of the physicochemical properties of the (1-x) (n-C 4 H 9) 4 NBF 4 -x Cnanodiamond composites was carried out. • The high ionic conductivity is due to the contribution of a 3.5 nm thick amorphous phase stabilized at the interface. • High ionic conductivity of order of 1.2*10−2 S/cm at 150C was observed. [ABSTRACT FROM AUTHOR]

White opaque single crystals of Na 6 Ge 2 S 6 O were obtained serendipitously during the preparation of Na 4 GeS 4. Then, pure glass and ceramic Na 6 Ge 2 S 6 O samples were synthesized from Na 2 S, GeS 2 , and GeO 2 reagents. The crystal structure was determined from powder and single crystal X-ray diffraction data. The physical properties were characterized by TG-DTA, SEM-EDX, Raman spectroscopy and electrochemical impedance spectroscopy. Na 6 Ge 2 S 6 O crystallizes with a new type of structure in the non-centro-symmetric space group P 2 1 2 1 2 1 , a = 6.96882 (6) Å, b = 7.04159 (6) Å, c = 26.7069 (2) Å, V = 1310.55 (2) Å3 and Z = 4. The asymmetric unit is built up of six Na+ cations surrounding a bi-tetrahedral complex anion, [S 3 GeOGeS 3 ]6−, which adopts a staggered conformation. The strongly distorted sodium polyhedra share edges and/or faces. The electrical conductivities of Na 6 Ge 2 S 6 O glass and ceramic at 25 °C are 2.9 × 10−5 S cm−1 (E a = 0.47 eV) and 1.8 × 10−7 S cm−1 (E a = 0.43 eV), respectively. [Display omitted] • The ternary system Na 2 S-GeO 2 -GeS 2 was investigated by solid state synthesis. • Glass and ceramic forms of the new Na 6 Ge 2 S 6 O compound were prepared. • Single crystals of Na 6 Ge 2 S 6 O were isolated after melting the Na 4 GeS 4 composition. • The new crystal structure was solved from powder and single crystal XRD data. • The electrical conductivity of amorphous Na 6 Ge 2 S 6 O is 2.9 × 10−5 S cm−1 at 25 °C. [ABSTRACT FROM AUTHOR]

The recently discovered anti-perovskites of the formula, Li 3 OCl 1 − x Br x , where x = 0 to 1 , have been garnering interest as potential candidates for solid electrolytes in battery applications. It is observed that the Li ion transport in these solids is rather slow, and unaccessible within typical molecular dynamics time scales. However, by judicially augmenting it with the accelerated sampling technique of metadynamics, the present study derives fresh insights on the nature of Li ion transport in these systems. The microscopic of ion migration along intra- and inter-octahedral channels, suggests that intra-octahedral channels account for over 95% Li transport in the system. The bromide end member offers lower free energy barriers, due to entropic factors resulting from the expansion of the lattice. However, the large free energy barriers estimated in the present work suggest that the undoped Li 3 OCl 1 − x Br x anti-perovskites are unlikely to exhibit superionic behavior. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, highly ionically conductive Li 6.5 La 3 Zr 1.5 Ta 0.1 Nb 0.4 O 12 (LLZTNO) fillers were blended into a poly(ethylene oxide) matrix to construct a composite solid-state electrolyte (CSSE). The LLZTNO fillers decrease the crystallinity of the PEO and provide extra lithium-ion transport pathways. Additionally, TFSI− anions are immobilized by the LLZTNO ceramic powders, and more Li ions are mobilized, increasing the overall ionic conductivity in CSSE. The PEO-LiTFSI-10% LLZTNO (i.e., PL-LLZTNO10%) CSSE shows the highest conductivity of 0.36 × 10−4 S cm−1 with a broad voltage window of 4.7 V at room temperature. The Li/ PL-LLZTNO10% CSSE/Li symmetric cells could operate for approximately 1200 h at 63 mV polarization voltage. The assembled solid-state LFP/PL-LLZTNO10%/Li cells deliver a 158.3 mAh g−1 capacity at 0.2C and 60 °C. After 300 cycles, its specific discharge capacity remains at 143.5 mAh g−1 with a Coulombic efficiency of 99.54%. [Display omitted] • PEO-LLZTNO composite electrolyte shows a broad electrochemical window of 4.7 V; • The assembled symmetric cell operates for 1200 h without short circuit; • The critical current density of PEO-LLZTNO electrolyte could reach 0.3 mA/cm2 with a capacity of 0.3 mAh/cm2; • The assembled composite solid-state lithium metal cells deliver 143.5 mAh g−1 with 99.54% Coulombic efficiency after 300 cycles. [ABSTRACT FROM AUTHOR]

A Raman and electrochemical impedance spectroscopy (EIS) joint study was performed on the (Nd,Tm)- and (Nd,Dy)-doped ceria systems, members of a promising class of materials to be used as electrolytes in solid oxide cells operating at intermediate temperatures (IT-SOCs). Raman and EIS data were collected in the 573–1073 K temperature range, i.e. in the operating temperature range of IT-SOCs, and analyzed with the aim to correlate ionic conductivity and defect chemistry. Defect aggregates growing within the CeO 2 -based matrix tend in fact to reduce and even suppress oxygen transport. A slope change in the trend of Raman shift of the Ce O vibration, as well as of the FWHM/intensity ratio of the same signal, occurs around the temperature where also the activation energy to ionic conduction changes its value. This common evidence is discussed in the light of defect aggregates stability, and in more detail in terms of decomposition of the 1 V O • • 2 RE Ce ′ trimers. [Display omitted] • MicroRaman and impedance spectroscopy measurements were performed on doped ceria. • A lower activation energy to ionic conductivity is revealed above 750 K. • A discontinuity in the Raman shift of the CeO2 signal occurs at the same temperature. • Defects aggregates negatively affect ionic conductivity in doped ceria electrolytes. • Due to their low configurational entropy, defect trimers dissociate above 750 K. [ABSTRACT FROM AUTHOR]

Hydride-ion conductors and mixed hydride-electronic conductors are promising materials for various applications, especially in (electro)chemical energy conversion and storage. Many of the hydride-ion conductors discovered to date are oxyhydrides with the K 2 NiF 4 -type structure. In this work, Cs 2 CaH 4 and Rb 2 CaH 4 , which crystallize in the K 2 NiF 4 -type structure, were synthesized and electrochemically characterized. By employing electrochemical impedance spectroscopy (EIS) and single-step chronoamperometry measurements, it is found that both materials show mixed ionic-electronic conductivity at moderate (100–200 °C) temperatures. The overall conductivity of both materials is increased by the release of hydrogen at elevated temperatures, indicating an effect of hydride vacancy concentration on the conductivity. This suggests that the ionic conductivity is due to hydride-ion transport, which is further supported by Climbing Imaged Nudged Elastic Band (CINEB) calculations. Cs 2 CaH 4 shows approximately equal ionic and electronic conductivity at 190 °C (total conductivity σ = 2.1 × 10−6 S cm−1), while Rb 2 CaH 4 (σ = 8.8 × 10−7 S cm−1 at 190 °C) is primarily an ionic conductor. As mixed hydride-electronic conductors, both materials show promise in chemical conversion and energy conversion applications. • Two K 2 NiF 4 -type mixed ionic/electronic conductors Rb 2 CaH 4 and Cs 2 CaH 4 successfully synthesized. • The compounds exhibit good ionic conductivity below 150 °C. • The ionic conductivity in the compounds is due to hydride ion transport. • Computational results indicate which paths hydride ions take through the materials. [ABSTRACT FROM AUTHOR]

Anti-perovskites are a kind of emerging solid electrolyte materials. The lithium rich anti-perovskite Li 3 OCl has been used as a solid electrolyte for lithium-ion batteries. It is rich in cations and is expected to solve the problem of low ionic conductivity of solid electrolyte materials. On this basis, this work theoretically modulates the ionic conductivity of lithium rich anti-perovskite by replacing halogen with superhalogen. Density functional theory (DFT) calculation results show that Li 3 OAlF 4 , Li 3 SAlF 4 , Li 3 SClO 4 and Li 3 SReO 4 display low activation energy (∼ 0.2 eV), and their ionic conductivities can reach 10−2 S cm−1 at room temperature. The improved ionic conductivities are attributed to the rotation of superhalogen which facilitates the movement of lithium ions; additionally, the volume effect caused by superhalogen is also an important factor. Finally, considering the stability and ionic conductivity, Li 3 SAlF 4 and Li 3 SReO 4 are predicted to be potential solid electrolyte materials for practical applications. [Display omitted] • Theoretical exploring a kind of ideal solid-state electrolyte materials. • The Li-rich anti-perovskite exhibits high ion conductivity by substitution of anion clusters. • The Li ion transport mechanism related with anion clusters is expounded. [ABSTRACT FROM AUTHOR]

For ever-growing energy demand, it is the imperative of time to develop advanced electrolyte materials which are compatible with Li + ion mobility in Lithium based batteries. In this study, polyvinyl alcohol (PVA)-LiNO3-Formamide (PLF) membrane complex has been developed for cost effective and mass fabrication of Li ion based energy storage devices. Improved Li + ion conducting PVA based polymer electrolytes in seven different PVA and LiNO3 blend compositions were prepared and characterized. Incorporation of Formamide (0.5 g) as plasticizer in the PVA-LiNO3 polymer matrix leads to a remarkable improvement in ionic conductivity (4.18 × 10−4 Scm−1) for a 0.27 g of LiNO 3 concentration at ambient temperature. Improvement in Li conductivity is due to change in crystalline nature as a consequence of PVA O-H---O intra/inter molecular H-bonding destabilization. Investigation on the trend of activation energy as a function of dopant concentration indicates that the activation energy decreases up to 0.27 g of LiNO 3. Lowest activation energy 0.21 eV is observed for this concentration. More interestingly, improved Lithium Transference Number (LITN) of 0.437 is obtained through Bruce-Vincent approach for the plasticized optimum conducting membrane (PLF4–0.27 g LiNO 3 concentration) which is better than that of the commercially available Li batteries. Underlying molecular level interactions in the models of PVA and its complexes were explored using M05-2×/6–31 + G (d,f) levels of theory and NCI analysis. From the least interaction energy of PVA-Formamide complex, it is inferred that metal-Oxygen coordination contributes much for the stabilization of PVA-LiNO 3 -Formamide, PVA-LiNO 3 , Formamide-LiNO 3 complexes. [Display omitted] • A hydrophilic PVA based Lithium ion conducting membrane has been prepared to develop cost effective energy storage device with environment friendly approach • Formamide has been considered as a plasticizing agent which improved the ionic conductivity in the membrane as this system has not been used before as a plasticizer in solid state electrolyte membrane. • Non-covalent forces involved in the molecular complexes were explored through electronic structure calculations and IGM analysis. [ABSTRACT FROM AUTHOR]

This study explores the structural and electrical properties of sodium carboxymethyl cellulose (NaCMC)–pectin (PC)–glycerol–NH 4 Br electrolyte films and investigates their potential applications in proton batteries. Plasticized solid polymer electrolyte (SPEs) films were fabricated using the solution casting method. The interaction between the salt and polymer blends was verified using Fourier-transform infrared (FTIR) analysis. Incorporation of various salt concentrations (up to 25 wt%) was found to enhance the amorphous phase of the polymer blend, as evidenced by X-ray diffraction (XRD) results. Additionally, the decrease in the glass transition temperature, as confirmed by DSC analysis, indicates that the inclusion of both plasticizer and salt contributed to this effect. An electrolyte with 25% wt. of NH 4 Br has the highest room temperature conductivity of 4.68 × 10−4 S cm−1. This electrolyte was employed to fabricate the proton battery for energy storage application. [Display omitted] • Plasticized PC/NaCMC-NH 4 Br has been successfully synthesized. • Plasticized PC/NaCMC-NH 4 Br SPE shows ionic conductivity of 4.68 × 10-4 (S cm-1) along with an LSV up to 2.4 V. • The plasticized PC/NaCMC-NH 4 Br sample with the highest conductivity exhibits a low crystallinity index (χ %) of 11.98. • Transport properties through Nyquist plot fitting aligned with ionic conductivity trend. • The proton battery with 25 wt% of salt concentration demonstrates an OCV of 1.2. [ABSTRACT FROM AUTHOR]

We present a 23Na nuclear spin dynamics model for interpreting nuclear magnetic resonance (NMR) spin-lattice relaxation and central linewidth data in the invert glass system Na 4 P 2 S 7-x O x , 0 ≤ x ≤ 7. The glassy nature of this material results in variations in local Na+ cation environments that may be described by a Gaussian distribution of activation energies. A consistent difference between the mean activation energies determined by NMR and DC conductivity measurements was observed, and interpreted using a percolation theory model. From this, the Na Na coordination number in the sodium cation sublattice was obtained. These values were consistent with jumps through tetrahedral faces of the sodium cages for the sulfur rich glasses, x < 5, consistent with proposed models of their short range order (SRO) structures. From NMR spin-echo measurements, we determined the Na Na second moment M 2 resulting from the Na Na magnetic dipole interaction of nearest neighbors. Values of M 2 obtained as a function of sodium number density N were in agreement with models for uniform sodium distribution, indicating that these invert glass systems form so as to maximize the average Na Na distance. A simple Coulombic attraction model between Na+ cation and X (=S−, O−) anion was applied to calculate the activation energy. In the range 1.5 ≤ x ≤ 7, an increase in activation energy with increasing oxygen content x occurred, and was consistent with the decrease in average anionic radius, and the increase in Coulombic attraction. For small oxygen additions, 0 ≤ x ≤ 1.5, the suggested minimum at low oxygen concentration seen in the activation energies obtained from DC conductivity data is not evident in the model. • Sodium glasses show promise as energy storage devices for wind/solar energy farms. • Nuclear dynamics was used to determine distributions of activation energies. • Sodium - sodium coordination number is consistent with face jumps through tetrahedral cages. • Sodium cations are uniformly distributed over the glass composition range. [ABSTRACT FROM AUTHOR]

The argyrodite solid electrolyte Li 6 PS 5 Cl is one of the promising candidates due to its high Li-ion conductivity for the application of all-solid-state lithium-ion batteries (ASSLIBs). Unfortunately, Li 6 PS 5 Cl argyrodite exhibits low stability against lithium metal anodes and oxide cathodes. One way to improve stability is by oxygen doping into Li 6 PS 5 Cl argyrodite. In this work, Li 6 PS 5 – 2.5x O 2.5x Cl (x = 0, 0.05, and 0.10) solid electrolytes with oxygen doping were successfully synthesized using liquid-phase synthesis for the first time. Therefore, the solid electrolyte with x = 0.05 exhibits high ionic conductivity with enhanced electrochemical stability against lithium metal and oxide cathodes. Argyrodites with x = 0.05 and x = 0.10 show superior capacity retention and higher Coulomb efficiency compared to x = 0. Moreover, the solid electrolytes also demonstrate better stability during Li symmetrical cell measurements. This experiment provides a controllable amount of oxygen doping into the Li 6 PS 5 Cl argyrodite solid electrolyte system in order to achieve high performance of ASSLIBs through liquid-phase synthesis. • The incorporation of P 2 O 5 oxide into sulfide-based Li 6 PS 5 Cl argyrodite solid electrolyte has been explored. • Oxide doping in argyrodite is achieved for the first time through liquid-phase synthesis. • We used Acetonitrile (ACN) and 1-Propanethiol (PTH) in our liquid-phase synthesis for the first time. • Doping oxides into argyrodite enhances battery cycle performance and lithium metal stability. [ABSTRACT FROM AUTHOR]

Mullite-phase bismuth gallate (Bi 2 Ga 4 O 9) was successfully synthesized with partial substitution of bismuth with alkaline-earth cation, Mg2+, Ca2+, Sr2+, and Ba2+. The effect of this substitution on the electrical conductivity was investigated. In this study, substitution with Ca2+ of Bi site was further studied for increasing the ionic conductivity as well as the phase stability in reducing atmospheres. Substitution with Ca2+ was found to be the most effective and with 12.5 mol% of Ca2+ as the optimized doping amount. Conductivity and stability in reducing atmospheres was increased down to p O2 ≤ 10−19 atm while keeping the conductivity of σ = 2.6 × 10−2 S·cm−1 at 973 K largely independent of oxygen partial pressure. Oxygen permeation analysis estimates 76% of theoretical oxygen permeation rate at 973 K suggesting main charge carrier is oxide ion. Partial electronic conductivity was measured with the ion blocking method. Oxide ion conductivity is dominated over wide p O2 range excepting for hole conduction at high p O2. Density functional theory (DFT) analysis on oxide ion diffusion route suggests oxygen hoping through lattice vacancy is main pathway for oxide ion conductivity in this doped Bi 2 Ga 4 O 9. Despite the low oxide ion conductivity in Mullite-phase oxide, it was found that Ca doped Bi 2 Ga 4 O 9 shows good oxide ion conductivity over wide p O2 range. • Substitution to the A-site with an alkaline-earth cation is successful for increasing conductivity in the material. • Addition of calcium expands the stability window of the material to low p O2 region. • Electrical conductivity is independent of oxygen partial pressure suggesting its ionic nature. • Oxygen permeation measurement establishes oxide ion as the main charge carrier. [ABSTRACT FROM AUTHOR]

The conductivity in the monoclinic polymorphs of Ln 2 MoO 6 (Ln = Sm, Gd, Dy) oxymolybdates was investigated by theoretical and experimental methods. A theoretical approach consisted of geometrical-topological analysis, bond valence site energy, kinetic Monte-Carlo (KMC) modeling and density functional theory (DFT) calculations. The theoretical results have shown that oxygen ionic conductivity is possible in all oxymolybdates with DFT migration energy <1.39 eV. We also calculated oxygen ionic conductivity at various temperatures (500–800 °C) using KMC modeling and found values higher than 10–3.5 S/cm at 800 ° C, which was in agreement with the experimental measurements. The total conductivity achieved ~10−5 S/cm for Sm 2 MoO 6 , ~10−4 S/cm for Gd 2 MoO 6 and ~10−3 S/cm for Dy 2 MoO 6 at 800 °C according to impedance spectroscopy data. The oxygen pressure isotherms in the Ln 2 MoO 6 (Ln = Sm, Gd, Dy) indicated electronic conductivity contribution in the temperature range of 500–800 °C. The experimental electromotive force (EMF) method also showed an increase in the contribution of electronic conductivity with the temperature growth. The activation energy of oxygen ionic diffusion according to EMF data was in the range of 0.78–1.27 eV. • An ionic mobility in the monoclinic Ln 2 MoO 6 was studied by theoretical approaches. • The conductivity decreased with increasing of the ionicity degree of Ln -O bonds. • All oxymolybdates are mixed conductors at 400–800 °C. • Dy 2 MoO 6 possesses highest total conductivity up to ~10−3 S/cm at 800 °C. [ABSTRACT FROM AUTHOR]

We report novel calcium-substituted perovskite-type solid state electrolyte with nominal composition Li 0.344 Sr 0.433 Ca 0.02 Ta 3/4 Hf 1/4 O 3 , which we compare with Li 3/8 Sr 7/16 Ta 3/4 Hf 1/4 O 3. The compounds were synthesized via solid-state reaction and studied by X-ray and neutron powder diffraction and electrochemical impedance spectroscopy. Neutron powder diffraction allowed the Li position in the structure to be accurately determined. Calcium-substituted phase showed higher Li-ion conductivity than the analogous calcium-free phase obtained with our synthesis method. High total Li-ion conductivities of 3.6 ± 1.0 × 10−4 S cm−1 (E a = 431 meV) at 30 °C were reached for calcium-substituted phase, and both bulk and grain-boundary conductivities increased compared to that of the calcium-free phase. The same experiment was conducted on Li 0.344 Sr 0.433 Ca 0.02 Ta 3/4 Zr 1/4 O 3 and led to the same conclusion compared to Li 3/8 Sr 7/16 Ta 3/4 Zr 1/4 O 3. Elemental analysis by energy-dispersive X-ray (EDX) of Li 0.344 Sr 0.433 Ca 0.02 Ta 3/4 Hf 1/4 O 3 showed the formation of an intermediary phase at grain boundaries, which contained essentially strontium, calcium, and oxygen. To better understand the increased bulk conductivity, neutron diffraction was performed on Li 0.344 Sr 0.433 Ca 0.02 Ta 3/4 Hf 1/4 O 3. The results demonstrate the importance of understanding and controlling the grain boundary composition, as much as the bulk composition, to improve the total ionic conductivity of solid electrolytes. For table of Contents Only: Enhanced conductivities with calcium-substituted Li 3/8 Sr 7/16 Ta 3/4 Hf 1/4 O 3 perovskite. Thorough structural characterization reveals intermediary phase at grain boundaries. [Display omitted] • A new calcium-substituted perovskite-type electrolyte has been synthetized. • Li-ion conductivity is two times higher than the analogous calcium-free phase. • The Li-ion conductivity of both grain and grain boundary is increased. • Neutron powder diffraction was used to determine the Li positions in the structure. • An intermediary phase at grain boundaries containing calcium is revealed. [ABSTRACT FROM AUTHOR]

In this study, dense sintered polycrystalline compacts (relative density: >95%) of Tysonite-type fluoride ion conductor, La 0.93 Ba 0.07 F 2.93 , with different grain sizes were prepared by applying the spark plasma sintering method, and their electrical conductivities were evaluated in order to understand the influence of microstructures on the ionic conductivity. The conductivity of the prepared compacts increased when increasing the sintering temperature up to 1273 K, and showed the highest value, e.g. 7.1 × 10−5 S cm−1 at 300 K, which was much higher than the reported values for sintered compacts of the same material. These were because the application of the spark plasma sintering technique enabled us the high densification of the sintered compacts and the increase in the sintering temperature enhanced the grain growth resulting in the decrease in the grain boundary resistance. The inhibitory effect of grain boundary on the ionic conduction was not significant when the density of the polycrystalline compacts was sufficiently high. On the other hand, when the sintering temperature was higher than 1273 K, small pores were formed along the grain boundaries and the conductivity was degraded with increasing the sintering temperature. Such a decrease in the conductivity could be interpreted by the increase in the grain boundary resistance due to the pore formation by the high temperature sintering. This work demonstrated that, for sintering polycrystalline (La,Ba)F 3 -based fluoride ion conductors, there is an optimum preparation condition to achieve the optimum microstructure i.e. high density, large grain size, and clean grain boundary, for high fluoride ion conduction. • Dense (La,Ba)F 3 compacts with different grain sizes were prepared by the spark plasma sintering. • Bulk and grain boundary conductivities were evaluated separately. • Influences of microstructures on ionic conductivity of (La,Ba)F 3 were investigated. [ABSTRACT FROM AUTHOR]