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

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

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

Microstructure control of composite electrodes comprising active materials and solid electrolytes is imperative to achieve sufficient ion‐ and electron‐conductive pathways for the development of all‐solid‐state Li ion batteries. Here, we synthesized Li10GeP2S12 solid electrolytes with various particle size distributions by milling and filtering. Impedance spectroscopy revealed that the ionic conductivities in the bulk were hardly changed by the synthetic processes. This enabled us to investigate only the microstructure effects on the electrochemical properties of the composite electrodes. Microscopic and electrochemical tests of the LiCoO2‐Li10GeP2S12 composite cathodes clarified that the size distributions of the Li10GeP2S12 drastically affected the microstructures in the composite cathodes, such as contacts at interfaces and voids between particles. The size distributions also contributed to the appropriate ratio of LiCoO2 to Li10GeP2S12 for superior charge/discharge properties. The (de)intercalation reversibly proceeded in the composite cathode using the filtered Li10GeP2S12 even though the ratio of Li10GeP2S12 decreased from 50 % to 30 % in volume. This study demonstrated the possibility of high‐energy‐density composite cathodes for all‐solid‐state batteries by control of microstructures in composite electrodes. [ABSTRACT FROM AUTHOR]

Argyrodites, Li6PS5X (X=Cl, Br, I), have piqued the interest of researchers by offering promising lithium ionic conductivity for their application in all-solid-state batteries (ASSBs). However, other than Li6PS5Cl (651Cl) and Li6PS5Br (651Br), Li6PS5I (651I) shows poor ionic conductivity (10−7 S cm−1 at 298 K). Herein, we present Al-doped 651I with I−/S2− site disordering to lower activation energy (Ea) and improve ionic conductivity. They formed argyrodite-type solid solutions with a composition of (Li6−3xAlx)PS5I in 0⩽x⩽0.10, and structural analysis revealed that Al3+ is located at Li sites. Also, the Al-doped samples contained anion I−/S2− site disorders in the crystal structures and smaller lattice parameters than the non-doped samples. Impedance spectroscopy measurements indicated that Al-doping reduced the ionic diffusion barrier, Ea, and increased the ionic conductivity to 10−5 S cm−1; the (Li5.7Al0.1)PS5I had the highest ionic conductivity in the studied system, at 2.6×10−5 S cm−1. In a lab-scale ASSB, with (Li5.7Al0.1)PS5I functioned as a solid electrolyte, demonstrating the characteristics of a pure ionic conductor with negligible electronic conductivity. The evaluated ionic conduction is due to decreased Li+ content and I−/S2− disorder formation. Li-site cation doping enables an in-depth understanding of the structure and provides an additional approach to designing better-performing SEs in the argyrodite system. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: With the rapid growth of soft electronic and ionotronic devices such as artificial tissues, soft luminescent devices, soft robotics, and human‐machine interfaces, there is a demanding need to accelerate the development of soft ionic conductive materials. To date, the first‐generation ionotronic devices are mainly based on hydrogels or ionogels. However, due to their intrinsic drawbacks, such as freezing or volatilization at extreme temperatures, and the leakage problem under external mechanical forces, the reliability of ionotronic devices under harsh conditions remains a great challenge. The advent of liquid‐free ionic conductive elastomers (ICEs) has the potentials to solve the issues related to the gel‐type soft conductive materials. The free ions shuttling within the ion‐dissolvable polymer network enable liquid‐free ICEs to exhibit unparalleled ionic conductivity and elasticity. Moreover, by tuning the composition and structure of the polymeric network, it is also feasible to integrate other desirable properties, such as self‐healing ability, transparency, biocompatibility, and stimulus responsiveness, into liquid‐free ICE materials. In this review, we summarize the design strategies of recently reported liquid‐free ICEs, and further explore the methods to introduce multifunctionality, which originate from the rational molecular design and/or the synergy with other materials. Moreover, we highlight the representative applications of liquid‐free ICEs in soft ionotronics. It is believed that liquid‐free ICEs might provide a unique material platform for the next‐generation ionotronics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: With the rapid growth of soft electronic and ionotronic devices such as artificial tissues, soft luminescent devices, soft robotics, and human‐machine interfaces, there is a demanding need to accelerate the development of soft ionic conductive materials. To date, the first‐generation ionotronic devices are mainly based on hydrogels or ionogels. However, due to their intrinsic drawbacks, such as freezing or volatilization at extreme temperatures, and the leakage problem under external mechanical forces, the reliability of ionotronic devices under harsh conditions remains a great challenge. The advent of liquid‐free ionic conductive elastomers (ICEs) has the potentials to solve the issues related to the gel‐type soft conductive materials. The free ions shuttling within the ion‐dissolvable polymer network enable liquid‐free ICEs to exhibit unparalleled ionic conductivity and elasticity. Moreover, by tuning the composition and structure of the polymeric network, it is also feasible to integrate other desirable properties, such as self‐healing ability, transparency, biocompatibility, and stimulus responsiveness, into liquid‐free ICE materials. In this review, we summarize the design strategies of recently reported liquid‐free ICEs, and further explore the methods to introduce multifunctionality, which originate from the rational molecular design and/or the synergy with other materials. Moreover, we highlight the representative applications of liquid‐free ICEs in soft ionotronics. It is believed that liquid‐free ICEs might provide a unique material platform for the next‐generation ionotronics. [ABSTRACT FROM AUTHOR]

Recently, eutectogels have gained significant attention as promising materials for wearable devices. However, developing eutectogels with integrated stretchability, good toughness, self‐healing, and self‐adhesive properties through non‐covalent scaffold assembly is a major challenge. In this study, a fully physically crosslinked double‐network (DN) eutectogel was fabricated by exploiting the high solubility and gelation of gellan gum in a deep eutectic solvent (DES) to form the first physically crosslinked network and combining it with supramolecular poly (2‐hydroxyethyl acrylate‐choline chloride, HEA‐ChCl). The resulting gel showed high stretchability (1835 %), toughness (7.65 MJ m−3), desirable ionic conductivity (0.41 mS cm−1), adhesion, and high transparency. Assembling the gel into strain sensors allows precise monitoring of human motion (finger, wrist, elbow, and knee). The results of this study suggest that gellan gum/poly (ChCl‐HEA) DN eutectogels have significant potential as highly sensitive and reliable strain sensors for wearable technology applications. [ABSTRACT FROM AUTHOR]

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

Gel polymer electrolytes (GPEs) are preferable in energy storage devices, owing to their high ionic conductivity and excellent compatibility with electrodes. In the current work, sodium‐conductive Na2Zn2TeO6 filler modified GPE membranes are fabricated, and their application performances in sodium‐ions batteries (SIBs) are demonstrated. With the modification of Na2Zn2TeO6 filler, the ionic conductivity of the GPEs is enhanced significantly, due to the decreased crystallinity and enlarged porosity of polymer membranes induced by Na2Zn2TeO6 modifier, which itself is a high ionic conductor. The modified GPE membranes exhibit enhanced ionic conductivity as high as 2.52×10−3 S/cm with a low activation energy of approximately 0.040 eV. The assembled Na3V2(PO4)3/C|GPE|Na battery delivers a high first discharge capacity of 93.3 mAh ⋅ g−1 at 0.5 C and promising capacity retention capability (98.4 % after 100 cycles) as well as excellent rate performance (83.5 mAh ⋅ g−1 at 5 C). This work proves that the performances of GPEs can be enhanced with the modification of ionic conductors similar to Na2Zn2TeO6, promoting the application of GPEs in energy storage devices. [ABSTRACT FROM AUTHOR]

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

To date, ionic conducting hydrogel attracts tremendous attention as an alternative to the conventional rigid metallic conductors in fabricating flexible devices, owing to their intrinsic characteristics. However, simultaneous realization of high stiffness, toughness, ionic conductivity, and freezing tolerance through a simple approach is still a challenge. Here, a novel highly stretchable (up to 660%), strong (up to 2.1 MPa), tough (5.25 MJ m−3), and transparent (up to 90%) ionic conductive (3.2 S m−1) organohydrogel is facilely fabricated, through sol–gel transition of polyvinyl alcohol and cellulose nanofibrils (CNFs) in dimethyl sulfoxide‐water solvent system. The ionic conductive organohydrogel presents superior freezing tolerance, remaining flexible and conductive (1.1 S m−1) even at −70 °C, as compared to the other reported anti‐freezing ionic conductive (organo)hydrogel. Notably, this material design demonstrates synergistic effect of CNFs in boosting both mechanical properties and ionic conductivity, tackling a long‐standing dilemma among strength, toughness, and ionic conductivity for the ionic conducting hydrogel. In addition, the organohydrogel displays high sensitivity toward both tensile and compressive deformation and based on which multi‐functional sensors are assembled to detect human body movement with high sensitivity, stability, and durability. This novel organohydrogel is envisioned to function as a versatile platform for multi‐functional sensors in the future. [ABSTRACT FROM AUTHOR]

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

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

Li 7 La 3 Zr 2 O 12 (LLZO) garnet is one of the most promising Lithium-ion solid electrolytes in all-solid-state Lithium-ion batteries, due to its higher chemical stability to Li metal and relatively higher lithium-ion conductivity. To further increase the electrical conductivity of LLZO, Sm 3+ is doped into the Zr 4+ site of LLZO so that excess Li occupies the position of the octahedral. Thereby lithium ion transport and increasing ionic conductivity are promoted. The optimal addition of Sm 3+ is 0.06. Li 7+x La 3 Zr 2-x Sm x O 12 (LLZSO, x = 0.06) electrolyte with cubic phase is obtained with sintering at 1200 °C for only 3 h. It has higher relative density and better ionic conductivity than the pristine LLZO. Its bulk and total ionic conductivity are ∼6.4 × 10 −4 S·cm −1 and 2.46 × 10 −4 S·cm −1 at 20 °C, respectively. [ABSTRACT FROM AUTHOR]

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

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

The disk-shaped sintered compacts consisting mainly of c -axis-aligned lanthanum silicate oxyapatite (LSO) polycrystals doped with K 2 O and Al 2 O 3 were prepared by templated grain growth method. The tabular single crystals of K 2 O- and F-doped LSO were used as template particles, and the Al 2 O 3 -doped LSO as matrix powder. The chemical formula derived from the average chemical composition of the constituent LSO crystal grains was (La 9.60 K 0.16 □ 0.24) Σ=10 (Si 5.48 Al 0.38 □ 0.14) Σ=6 O 26 , where □ denotes vacancies in La and/or Si sites. One of the doped LSO grains was examined by single-crystal X-ray diffraction to confirm that the crystal structure was isomorphous to those previously reported. Other coexisting phases were 0.16 mol% LaAlO 3 and 0.34 mol% SiO 2 -rich interstitial material (probably in a liquid state at high temperature). With increasing temperature from 773 to 1073 K, the total oxide-ion conductivity (σ total) along the grain-alignment direction steadily increased from 1.31 × 10−4 to 3.21 × 10−3 S cm−1, each value of which was, at the same temperature, more than 7.7 times larger than that of the randomly grain-oriented polycrystal with the same bulk chemical composition. The larger σ total -value of the former polycrystal would be due to the significantly higher oxide-ion conductivity along the c -axis direction of the doped LSO. A solid oxide fuel cell (SOFC) using the textured polycrystal as the electrolyte was constructed and tested for power generation. The maximum power density was satisfactorily high at 873 K, indicating that the c -axis-aligned polycrystals of doped LSO would be potentially applicable as electrolytes for the SOFCs operating at medium to low temperatures. • Textured polycrystal of doped LSO successfully prepared by TGG method • Crystal structure of doped LSO is determined by single-crystal XRD • Grain alignment and doping effectively enhance the conductivity of LSO polycrystal • Textured polycrystal is potentially used as electrolytes of low-temperature SOFCs [ABSTRACT FROM AUTHOR]

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

Grain-aligned polycrystalline lithium titanogallate, Li 0.91 Ti 0.48 Ga 4.40 O 8 (LTGO), was successfully prepared by the combined techniques of reactive diffusion and ion exchange. We firstly synthesized the b -axis-oriented polycrystal of sodium titanogallate (NTGO) by the reactive diffusion between NaGaO 2 and Ga 2 TiO 5 at 1323 K for 24 h, followed by the ion-exchange reaction of Li + for Na + at 773 K for 125 h. The crystal structure of resulting LTGO (space group C 2/ m ) was isomorphous with that of the original NTGO. Both crystal structures were built up of five types of polyhedra; [ M O 7 ] ( M = Li or Na), [(Ti,Ga)O 6 ], [Ga1O 6 ], [Ga2AO 4 ], and [Ga2BO 6 ]. There was a marked difference between the two structures for the coordination environment of M ; the centroid-to- M distance of [LiO 7 ] (0.026 nm) was significantly larger than that of [NaO 7 ] (0.008 nm). The lithium-ion conductivity along the b -axis steadily increased from 3.41 × 10 − 4 to 6.21 × 10 − 4 S cm − 1 with increasing temperature from 773 to 1073 K. The activation energy of conduction was 0.22 eV. The combination of the two distinct techniques would enable us to synthesize the grain-aligned polycrystalline materials with various constituent compounds and chemical compositions. [ABSTRACT FROM AUTHOR]

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

In the past decade, the research in designing fast oxygen conducting materials for electrochemical applications has largely shifted to microstructural features, in contrast to material-bulk. In particular, understanding oxygen energetics in heterointerface materials is currently at the forefront, where interfacial tensile strain is being considered as the key parameter in lowering oxygen migration barriers. Nanocrystalline materials with high densities of grain boundaries have also gathered interest that could possibly allow leverage over excess volume at grain boundaries, providing fast oxygen diffusion channels similar to those previously observed in metals. In addition, near-interface phase transformations and misfit dislocations are other microstructural phenomenon/features that are being explored to provide faster diffusion. In this review, the current understanding on oxygen energetics, i.e., thermodynamics and kinetics, originating from these microstructural features is discussed. Experimental observations, theoretical predictions and novel atomistic mechanisms relevant to oxygen transport are highlighted. In addition, the interaction of dopants with oxygen vacancies in the presence of these new microstructural features, and their future role in the design of future fast-ion conductors, is outlined. [ABSTRACT FROM PUBLISHER]

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

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

Garnet solid electrolyte is expected to become the electrolyte of choice for next-generation solid-state batteries due to its high ionic conductivity and wide electrochemical window. However, the poor interfacial contact between electrolyte and electrodes limits the battery performance. In this work, the interface between the garnet and cathode is improved by utilizing a deep eutectic electrolyte (DEE) composed of 2,2′-dipyridyl disulfide and lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) with high ionic conductivity and viscosity. It can favorably bind carbon and LiFePO 4 particles, forming an intimate contact between the garnet and active material. In addition, by utilizing a succinonitrile gel electrolyte between the lithium metal anode and garnet, the assembled solid-state cell shows improved interfacial stability and promising cycling performance, i.e. , a high initial discharge capacity of 134.2 mAh g−1 and capacity retention of 97.8% after 100 cycles at 0.2 C. [Display omitted] • A gel electrolyte is used to improve the interface between lithium metal anode and garnet. • A deep eutectic electrolyte is used to improve the interface between garnet and cathode. • The solid-state battery with improved interfaces shows excellent capacity retention. [ABSTRACT FROM AUTHOR]

Three solid-state imidazolium iodides have been designed and synthesized for use as all-solid-state electrolytes in solid-state dye-sensitized solar cells (ssDSSCs). The effect of substituents in the imidazolium ring on the ionic conductivity and solar cell performance of ssDSSCs has been investigated. As compared to the methyl-ethyl-substituted imidazolium iodide, replacement of one alkyl group (the methyl group) with an ester group increases the ionic conductivity and solar cell performance significantly, and further replacement of the other alkyl group (the ethyl group) with a hydroxyethyl group further increases the ionic conductivity and solar cell performance significantly. A power conversion efficiency of 7.45% has been achieved under the irradiation of simulated AM1.5G solar light (100 mW cm-2) with the ssDSSC using the hydroxyethyl and ester co-functionalized imidazolium iodide based solid-state electrolyte and a metal-free organic dye sensitizer. The performance of solid-state dye-sensitized solar cells can be tuned by varying the substituents in the imidazolium ring of the solid ionic conductor. The power conversion efficiency has been improved gradually by replacing the alkyl group with the ester group and further with the hydroxyethyl group due to the significant increase in short-circuit photocurrent. [ABSTRACT FROM AUTHOR]

Highlights: [•] Yttria-Stabilized Zirconia (YSZ), an intrinsic ionic conductor, can oxidize soot. [•] YSZ lattice ions are the active oxygen species for initiating the soot combustion. [•] The soot oxidation process on YSZ involves a fuel-cell-type electrochemical mechanism. [•] YSZ porous membranes were fabricated to simulate Diesel Particulate Filters. [•] YSZ porous membranes are effective for soot filtering. [ABSTRACT FROM AUTHOR]

Abstract: Dual-phase membranes consisting of an ionic or mixed conducting ceramic phase and a molten carbonate phase are permeable only to carbon dioxide at high temperatures. This paper studies the effects of the pore structure of ceramic supports on carbon dioxide permeation properties of dual-phase membranes consisting of La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF) and eutectic Li2CO3–Na2CO3–K2CO3 carbonate phase. Porous LSCF supports with different pore structures were prepared by pressing LSCF powders followed by sintering at various temperatures. The porosity to tortuosity and solid fraction to tortuosity ratios for the porous LSCF supports were characterized by helium permeation and electrical conductivity measurements. The direct infiltration method allows complete filling of the ceramic support pores by the carbonate. CO2 permeance of the dual-phase membranes increases, and after reaching a maximum, decreases with increasing support sintering temperature or support porosity (carbonate fraction). A total conductance in terms of the effective carbonate and ionic conductivities (intrinsic conductivity modified by the carbonate or solid fraction to tortuosity ratio) is introduced and used to explain experimental results. The results show that the CO2 permeance of the dual-phase membrane is controlled not only by the intrinsic carbonate and oxygen ionic conductivities of the carbonate and ceramic phases, but also the carbonate or solid fraction to tortuosity ratio. Adjusting pore and solid microstructure of ceramic support is critical to maximize CO2 permeance of the dual-phase membranes. [Copyright &y& Elsevier]

The new field of nano-ionics is expected to yield large improvements in the performance of oxide-based energy generation and storage devices based on exploiting size effects in ion conducting materials. The search for novel materials with enhanced ionic conductivity for application in energy devices has uncovered an exciting new facet of oxide interfaces. With judicious choice of the constituent materials, oxide heterostructures can exhibit enhanced ion mobility compared to the bulk counterparts. Here we review recent experimental and theoretical progress on enhancement of oxide-ion conductivity arising in oxide ultrathin layers and at their interfaces, and describe the different scenarios, space-charge effects, epitaxial strain, and atomic reconstruction at the interface, proposed to account for the observed conductivity enhancement. [ABSTRACT FROM PUBLISHER]

[Display omitted] • TBP and [BMMIm][NTf 2 ] act as the mixed solvent of organic-ionogels. • TBP reduces the viscosity of the solution and enhances ionic conductivity. • Organic-ionogels are hydrophobic and flame retardant. • Organic-ionogels exhibit high stress sensitivity and apply in flexible touch screens. Very different from electronic conductors, ionic conductors usually possess some unique functions such as stretchability, transparency and ionic conductivity, thus exhibiting a great promise in the flexible wearable electronic devices. Herein, we develop a novel stretchable transparent organic-ionogel (OIG-TBP-50) via a rapid photo-curing process, in which we select the mixture of tributyl phosphate (TBP) and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)amine ([BMMIm][NTf 2 ]) as fireproof and conductive solvent, respectively. Just benefiting from the good synergistic effect of TBP and [BMMIm][NTf 2 ], our-designed OIGs demonstrate excellent hydrophobicity and flame resistance as well as perfect stretchability (757%), high transparency (93%) in visible region, good environmental stability, wide temperature tolerance range (from −55 °C to 180 °C) and high ionic conductivity (1.73 × 10-3 S cm−1 at room temperature). In addition, our stretchable transparent OIGs even could light LED lamps under an alternating current field when directly used as the flexible conductive substrate. Further applying such OIGs as ionic conductor to assemble flexible sensor and touch screen, both of them could transport rapid signal response under slight touch stress. [ABSTRACT FROM AUTHOR]

Thermal runaway reactions resulting in catastrophic battery failure and combustion have invigorated a search for non-flammable electrolytes. We report the synthesis of non-flammable inorganic lithiated carbon phosphonitride (Li–C–P–N) amorphous solids in various solvents, their spectroscopic and other characterization aimed at greater molecular structure understanding, and their ionic conductivities. The resin precursor to this polymeric material is the product of reacting solvated P(CN) 3 and LiN(CN) 2 ​at room temperature. The resulting resin can be cast from various polar aprotic solvents and produces Li–C–P–N films upon drying. The reaction mechanism was studied by time-resolved 31P solution NMR. A fully cured sample was studied by 31P, 13C and 7Li MAS NMR, including variable temperature 7Li MAS NMR observations of changes in satellite transitions arising from Li ​+ ​ion motions. Films dried at room temperature under inert atmosphere were temperature cycled as high as 250 ​°C to measure conductivity as a function of temperature and thermal curing. Thermally treated, partially solvated Li–C–P–N films cast from pyridine and dimethoxyethane/acetonitrile exhibit ionic conductivities as high as 10−5 ​S ​cm−1 above 100 ​°C, depending on temperature and cure procedure, although conductivity drops dramatically in films held above 150 ​°C. We propose that the conductivity of Li+ ions through the films is highly dependent on the presence and identity of tightly-bound solvent, the presence of excess LiN(CN) 2 retained in the Li–C–P–N matrix, as well as the structure of the cross-linked Li–C–P–N network. [Display omitted] • P(CN) 3 reacts with LiN(CN) 2 in non-protic mutual solvents to make a thermosetting resin. • This resin is an ionic conductor, which is most conductive while still solvated. • Upon thermal curing the resin forms a lithium carbonphosphonitride solid. • Characterized by electrical measurements, IR, thermal analysis, and solid state NMR. • 7Li MAS NMR shows that ion mobility of cured solid increases with temperature. [ABSTRACT FROM AUTHOR]

Much of the research effort in the past decade has been closely focused on finding suitable solid electrolytes with high ionic conductivity for various applications. In this context, the compound Na 3 La(AsO 4) 2 was synthesized using the molten salt (flux) method and its structure was solved from the single-crystal X-ray diffraction data for the first time. Na 3 La(AsO 4) 2 crystallizes in the monoclinic space group P2 1 /c (#14) with a ​= ​19.451(4)Å; b ​= ​5.554(1)Å; c ​= ​14.365(3)Å; β ​= ​90.035(2)°. Its crystal structure consists of an open 3D network built of [LaO 8 ] polyhedra sharing oxygen corners and edges with neighboring [AsO 4 ] tetrahedra. Tunnels in the [010] direction accommodate Na+ cations. The ionic conductivity was investigated experimentally and computationally. High-temperature ac-conductivity measurements yielded the highest ionic conductivity of 1.93 ​× ​10−4 ​S ​cm−1 ​at 700 ​°C with the apparent activation energy E a ​= ​0.85eV. A complementary analysis through the bond valence site energy calculation (BVSE), revealed that the structure of Na 3 La(AsO 4) 2 favors a 3D ionic diffusion pathway with the empirical activation energy of 1.061 ​eV for the long-range migration of Na+ ions. 3D bond-valence sum energy maps of Na 3 La(AsO 4) 2 with all possible Na+ ​diffusion pathways. [Display omitted] • A novel arsenate Na 3 La(AsO 4) 2 was synthesized using the molten salt (flux) method. • Its crystal structure was determined by single-crystal X-ray diffraction. • The purity of the powder was verified by conventional Rietveld refinement. • The ionic conductivity of Na 3 La(AsO 4) 2 was probed by Electrochemical Impedance Spectroscopy (EIS). • Probable diffusion pathways of Na ​+ ​are simulated by means of Bond valence site energy (BVSE) model. [ABSTRACT FROM AUTHOR]

• Ionic conductor oxide perovskites are predicted. • PCA and PLS throughout multivariate technique are employed. • Thermodynamic stability trend. • Migration and activation energies are analyzed. • Emerging various empirical rules are developed. We present in this work a strategy for predicting new oxide perovskites with the potential for achieving high ionic conductivity for applications as a solid oxide fuel cell (SOFC). We employ a throughout multivariate technique based the principal component analysis (PCA) and the partial least square methods (PLS) in order to identify empirical design rules (activation and migration energies) for stable ionic conductors. Among the 892 tested hypothetical oxide perovskites, which yet to be experimentally synthetized, ~150 compounds may exhibit an interesting potential as ionic conductors. These results may serve as a map for the design of perovskite-related solid electrolytes. [ABSTRACT FROM AUTHOR]

• A gentle surface engineering strategy was applied to surface decoration of β -Li x V 2 O 5. • The rate and cycling performance of β -Li x V 2 O 5 were boosted after surface modification. • The rGO/LaPO 4 /Li x V 2 O 5 composite exhibits high capacity retention of 84.1% after 100 cycles. • The multiple Li insertion activity and electrode interface was facilitated by surface decoration. The β- phase lithium vanadium oxide bronze (β- Li x V 2 O 5) with high theoretic specific capacity up to 440 mAh g−1 is considered as promising cathode materials, however, their practical application is hindered by its poor ionic and electronic conductivity, resulting in unsatisfied cyclic stability and rate capability. Herein, we report the surface decoration of β- Li x V 2 O 5 cathode using both reduced oxide graphene (rGO) and ionic conductor LaPO 4 , which significantly promotes the electronic transfer and Li+ diffusion rate, respectively. As a result, the rGO/LaPO 4 /Li x V 2 O 5 composite exhibits excellent electrochemical performance in terms of high reversible specific capacity of 275.7 mAh g−1 with high capacity retention of 84.1% after 100 cycles at a current density of 60 mA g−1, and acceptable specific capacity of 170.3 mAh g−1 at high current density of 400 mA g−1. The cycled electrode is also analyzed by electrochemical impedance spectroscopy, ex-situ X-ray diffraction and scanning electron microscope, providing further insights into the improvement of electrochemical performance. Our work provides an effective approach to boost the electrochemical properties of lithium vanadates for practical application in lithium ion batteries. [ABSTRACT FROM AUTHOR]