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• Ocean as a means of gigaton scale direct storage of atmospheric carbon. • Alkalinity transfer between deep and surface ocean for direct CO 2 capture. • Electrochemical ion selective electrodes to enhance surface ocean alkalinity. • Proof-of-concept enables a new family of scalable climate change solutions. The oceans play a major role in moderating atmospheric CO 2 levels. Enhanced CO 2 uptake into ocean waters can be achieved by the provision of appropriate cations to the surface ocean, an approach known as ocean alkalinity enhancement (OAE). Here, we present a calcium ion battery approach that enhances alkalinity via electrochemical manipulation of seawater calcium concentrations. We demonstrate the efficacy of this approach using a potassium barium iron cyanide [K 2 BaFe(CN) 6 ] (PBFC) electrode, a Prussian blue analogue, to move calcium ions from one reservoir of seawater to another. Using material and electrochemical characterization of the Ca2+ ion insertion and expulsion properties of PBFC in synthetic seawater, we determine the repeatability of Ca2+ ion insertion and expulsion from the PBFC electrode. Our analyses prove a 2.75 % increase in seawater alkalinity via the PBFC electrode, which yields 2.64 mg CO 2 (0.72 mg C) uptake per liter of seawater. This proof-of-concept method offers a unique, low-cost, energy efficient electrochemical approach for atmospheric carbon dioxide removal that can combine with marine-based renewable energy to enable a new family of effective, scalable climate change solutions. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical stability and high electrical conductivity under the operating conditions of solid oxide fuel cell (SOFC) are considered as the momentum for innovating solid electrolytes and electrodes. In this paper, we report synthesis, structure, chemical stability and electrical conductivity of novel co-doped Ce0.9−x Y0.1Mn x O2−δ (x = 0–15 mol%) (CYMO). X-ray diffraction of Mn and Y-doped CeO2 shows the formation of fluorite-type structure with a space group Fm-3m. A few weak peaks corresponding to a tetragonal Mn3O4 phase has been detected in some samples. Solubility of Mn in ceria is explained by considering the influence of the ionic radius, the crystal structure and its electronic structure. Thermal analysis shows dissimilarity between the reduction behavior of Ce0.9Mn0.1O2−δ and Ce0.9−x Y0.1Mn x O2−δ . Ce0.8Y0.1Mn0.1O2−δ exhibited the highest conductivity of ∼6 × 10−2 S cm−1 and 0.15 S cm−1 at 700 °C in air and H2, respectively. Surface studies have confirmed the formation of S species upon exposure to 30 ppm H2S in H2 and a mechanism for S poisoning is presented. [ABSTRACT FROM AUTHOR]

Perovskite-type structure oxides with the nominal chemical composition Nd 1-x Sr x Co 0.8 Fe 0.2 O 3− δ (0 ≤ x ≤ 0.85) (NSCF) were synthesized by solid-state method to investigate the effect of Sr-doping on the crystal structure and electrochemical performance in the intermediate temperature range of 600 °C–750 °C. The electrical conductivity of the sintered NSCF pellets was found to be in the range of 300–1000 S cm−1. All the NSCF compositions showed a transition from semiconducting to metallic behavior with an increase in temperature. NSCF showed reactivity with the La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3−δ (LSGM) electrolyte. The electrochemical performance was tested by preparing the symmetrical cells with the configuration 70 wt% NSCF +30 wt% LSGM using LSGM electrolyte in the temperature range of 650–800 °C. AC-impedance results showed a decrease in polarization resistance (Rp) of the cathode with increase in Sr-doping due to increase in electrical conductivity. Among the samples studied, composite electrode of Nd 0.3 Sr 0.7 Co 0.8 Fe 0.2 O 3− δ – LSGM showed the lowest area specific resistance (ASR) of 0.1 Ω cm2 at 750 °C in air. It was chosen to investigate the effect of pO 2 on the electrochemical performance of the cathode to determine the rate determining step (RDS) in oxygen reduction reaction (ORR). Dissociation of molecular oxygen into oxygen atoms seems to be the RDS in the ORR. • NSCF cathodes are synthesized by solid-state method for IT SOFCs. • Sr-doping improved the cathode performance for oxygen reduction reaction. • ASR of 0.1 Ω cm2 at 750 °C was achieved for Nd 0.3 Sr 0.7 Co 0.8 Fe 0.2 O 3− δ. [ABSTRACT FROM AUTHOR]

Abstract: We report the effect of Y substitution for Nb on Li ion conductivity in the well-known garnet-type Li5La3Nb2O12. Garnet-type Li5La3Nb2−x Y x O12−δ (0≤x≤1) was prepared by ceramic method using the high purity metal oxides and salts. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), 7Li nuclear magnetic resonance (Li NMR) and AC impedance spectroscopy were employed for characterization. PXRD showed formation of single-phase cubic garnet-like structure for x up to 0.25 and above x =0.25 showed impurity in addition to the garnet-type phases. The cubic lattice constant increases with increasing Y content up to x =0.25 in Li5La3Nb2− x Y x O12−δ and is consistent with expected ionic radius trend. 7Li MAS NMR showed single peak, which could be attributed to fast migration of ions between various sites in the garnet structure, close to chemical shift 0ppm with respect to solid LiCl and which confirmed that Li ions are distributed at an average octahedral coordination in Li5La3Nb2− x Y x O12− δ . Y-doped compounds showed comparable electrical conductivity to that of the parent compound Li5La3Nb2O12. The x =0.1 member of Li5La3Nb2− x Y x O12− δ showed total (bulk + grain-boundary) ionic conductivity of 1.44×10−5 Scm−1 at 23°C in air. [Copyright &y& Elsevier]

Abstract: We report synthesis, structure and dielectric properties of double perovskite-type Ba3−x K x CaNb2O9−δ (x =0.5, 0.75, 1, 1.25) (KBCN). Powder X-ray diffraction (XRD) confirmed the formation of double perovskite-type structure and lattice constant decreases with increasing K in KBCN. AC impedance study showed a single semicircle over the investigated temperatures and frequencies in dry H2, H2 +3% H2O, 3% H2O+N2, while two semicircles were observed at low temperatures in air, which could be attributed to bulk and grain-boundary contributions. Unlike un-doped BCN, KBCN exhibits negligible grain-boundary and electrode effects to the total electrical properties and is consistent with perovskite-type K-doped BaZrO3. The bulk dielectric constant and dielectric loss were found to increase with increasing K content in KBCN and also found to change with sintering temperature. Among the samples investigated, Ba1.75K1.25CaNb2O9−δ sintered at 1100°C showed the highest dielectric constant of 65 at 106 Hz and dielectric loss of 0.14 at 400°C in air. Isothermal dielectric constant and electrical conductivity at 1MHz were found to be independent at elevated temperatures, while vary at low-frequency and low temperatures. Below 700°C, dielectric constant and dielectric loss decreases with increasing frequency, whereas an opposite trend was observed for the electrical conductivity. [Copyright &y& Elsevier]

Abstract: In the present work, we have explored novel Nd2WO6-type structure Sm2−x A x M1−y B y O6−δ (A=Ca, Sr; M=Mo, W; B=Ce, Ni) as precursor for the development of solid oxide fuel cells (SOFCs) anodes. The formation of single-phase monoclinic structure was confirmed by powder X-ray diffraction (PXRD) for the A- and B-doped Sm2MO6 (SMO). Samples after AC measurements under wet H2 up to 850°C changed from Nd2WO6-type structure into Sm2MoO5 due to the reduction of MoVI that was confirmed by PXRD and is consistent with literature. The electrical conductivity was determined using 2-probe AC impedance and DC method and was compared with 4-probe DC method. The total electrical conductivity obtained from these two different techniques was found to vary within the experimental error over the investigated temperature of 350–650°C. Ionic and electronic conductivity were studied using electron-blocking electrodes technique. Among the samples studied, Sm1.8Ca0.2MoO6−δ exhibits total conductivity of 0.12Scm−1 at 550°C in wet H2 with an activation energy of 0.06eV. Ca-doped SMO appears to be chemically stable against reaction with YSZ electrolyte at 800°C for 24h in wet H2. The ionic transference number (t i) of Sm1.9Ca0.1MoO6−δ in wet H2 at 550°C (pO2 =10−25.5 atm) was found to be about 0.012 after subtraction of electrical lead resistance from the 2-probe AC data and showed predominate electronic conductors. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the synthesis, structure, chemical stability and electrical transport properties of Ti substituted Ba3CaNb2O9 (BCN) to develop electrolytes for proton conducting solid oxide fuel cells (H-SOFCs). The powder X-ray diffraction (PXRD) of Ba3CaNb2−x Ti x O9−δ (x =0.1, 0.15, 0.2, 0.25 and 0.3) and Ba3Ca1.18Nb1.82−x Ti x O9−δ (x =0.15 and 0.25) showed formation of double perovskite-like structure with lattice constant comparable to that of Ba3Ca1.18Nb1.82O9−δ (BCN18). Scanning electron microscopy (SEM) showed dense and pore-free microstructure for Ba3CaNb1.75Ti0.25O8.875. PXRD and Fourier transform infrared (FTIR) spectroscopy data confirmed long-term stability of Ba3CaNb2−x Ti x O9−δ and Ba3Ca1.18Nb1.82−x Ti x O9−δ in boiling H2O and in CO2 at elevated temperatures. The AC impedance investigation showed contribution due to bulk, grain-boundary and electrode effect at low temperatures. The electrical conductivity of studied materials were measured in different medium including dry air, dry H2, wet H2, wet N2 and D2O. Increase in conductivity in wet N2 and decrease in conductivity in D2O confirmed the proton conduction in Ba3CaNb1.75Ti0.25O9-δ . Among Ti-substituted compounds investigated in this study, Ba3Ca1.18Nb1.57Ti0.25O8.605 showed the highest conductivity of 3.5×10−4 Scm−1 at 400°C in wet N2 (3%H2O), which is comparable to reported values of Ba2Ca0.79Nb0.66Ta0.55O6−δ and BCN18. [Copyright &y& Elsevier]

Abstract: In this paper, we report the synthesis, chemical stability and electrical properties of three new Ta-substituted double perovskite-type Ba2Ca2/3Nb4/3O6 (BCN). The powder X-ray diffraction (PXRD) confirms the formation of double perovskite-like structure Ba2(Ca0.75Nb0.59Ta0.66)O6−δ , Ba2(Ca0.75Nb0.66Ta0.59)O6−δ and Ba2(Ca0.79Nb0.66Ta0.55)O6−δ . The PXRD of CO2 treated (800°C; 7 days) and water boiled (7 days) samples remain the same as the as-prepared samples, suggesting a long-term structural stability against the chemical reaction. The electrical conductivity of the investigated perovskites was found to vary in different atmospheres (air, dry N2, wet N2, H2 and D2O+N2). The AC impedance investigations show bulk, grain-boundary and electrode contributions in the frequency range of 0.01Hz to 7MHz. Below 600°C, the bulk conductivity in wet H2 and wet N2 was higher than in air, dry H2 and dry N2. However, an opposite trend was observed at high temperatures, which may be ascribed to p-type electronic conduction. The electrical conductivity of the investigated perovskites was decreased in D2O+N2 compared to that of H2O+N2 atmosphere. This clearly shows that the investigated Ta-doped BCN compounds exhibit proton conduction in wet atmosphere which was found to be consistent with water uptake. The water uptake was further confirmed by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) characterization. Among the samples investigated, Ba2(Ca0.79Nb0.66Ta0.55)O6−δ shows the highest proton conductivity of 4.8×10−4 Scm−1 (at 1MHz) at 400°C in wet (3% H2O) N2 or H2, which is about an order of magnitude higher than the recently reported 1% Ca-doped LaNbO4 at the same atmosphere and at 10kHz. [Copyright &y& Elsevier]

A conventional solid-state sintering method was used to prepare double perovskite structured compounds BCN (Ba 2 Ca 0.67 Nb 1.33 O 6), BCNCo (Ba 2 Ca 0.67 Nb 1.33-x Co x O 6-δ) and BCNCoFe (Ba 2 Ca 0.67 Nb 0.67 Co 0.66-y Fe y O 6-δ), which exhibit significant chemical stability in nitrogen, air, and 2 % CO 2 (balanced by nitrogen). SEM images show that the Co dopant causes a dense microstructure for BCNCo compounds. In contrast, the introduction of Fe tends to produce a porous and web-like microstructure for the BCNCoFe series. Ba 2 Ca 0.67 Nb 0.67 Co 0.66 O 6-δ has a reasonable response (recovery) time at 750 °C and it seems suitable for CO 2 detection at elevated temperatures. Among the BCNCoFe compounds, Ba 2 Ca 0.67 Nb 0.67 Co 0.33 Fe 0.33 O 6-δ has the largest capacitance as the CO 2 concentration changes from 0 to 2000 ppm, and it exhibits satisfactory sensitivity and repeatability in the temperature range of 450–700 °C with an extra voltage of 0.1 V. To further consider the Ba 2 Ca 0.67 Nb 0.67 Co 0.33 Fe 0.33 O 6-δ compound for CO 2 sensing, a sol-gel method was utilized. The sol-gel-prepared Ba 2 Ca 0.67 Nb 0.67 Co 0.33 Fe 0.33 O 6-δ senses CO 2 well, and its concentration changes from 0 to 2000 ppm (or from 0 to 300 ppm) in the temperature range of 400–600 °C. The different CO 2 sensing properties of all prepared double perovskite compounds can be interpreted by the different surface areas that play critical roles in the chemical adsorption of related gaseous species. [ABSTRACT FROM AUTHOR]

Abstract The electrochemical performance of solid oxide fuel cell (SOFC) depends on functional properties of the anode, the cathode and the electrolyte that are being employed. There is a need for better cathode catalyst to decrease operating temperature of SOFCs. Here, we report a layered perovskite-type Ruddlesden-Popper structure La 0.6 Sr 1.4 Co 0.2 Fe 0.8 O 4+δ (RP-LSCF) as cathode for SOFCs. The structural stability, thermal expansion, electrical, and fundamental electrochemical properties of RP-LSCF were investigated. The O 2 reduction reaction (ORR) and O 2 surface exchange properties of RP-LSCF and Gd-doped CeO 2 (GDC)-RP-LSCF composite were studied using symmetrical cells. Area normalized resistances for charge transfer (R i) and surface exchange processes (R s), and total polarization are found to be 0.14, 0.28 and 0.42 Ω cm2 at 800 °C, respectively. The exchange current density and oxygen surface exchange co-efficient for RP-LSCF are 54.53 mA cm−2 and 1.15 × 10−6 cm s−1 at 800 °C, respectively. Addition of nano-GDC with RP-LSCF leads to increase of polarization resistances, while the activation energies for charge transfer and surface exchange processes are reduced significantly. For the first time, we report a dielectric loss tangent analysis corresponding to the electrode phenomena in RP-LSCF and GDC-RP-LSCF to understand the electrical losses associated with SOFC cathode (ORR) processes. [ABSTRACT FROM AUTHOR]

This study addresses the influence of A-and B-site co-doping on the chemical and electrical properties of perovskite-type Ba 0.5 Sr 0.5 Ce 1− x − y − z Zr x Gd y Y z O 3−δ (0 < x < 0.5; y = 0, 0.1, 0.15; z = 0.1, 0.2). The powders synthesised at 1450 °C through solid state (ceramic) reaction showed relative density greater than 94% by Archimedes method, and is supported by dense microstructure using scanning electron microscopy images. The effect of doping electronegative elements on the A-and B-site on chemical stability is exemplified by dopant dependent chemical stability under CO 2 and water vapour. Thermogravimetric analysis (TGA) of the powdered samples under CO 2 : N 2 (1:1) showed variation in weight gain with respect to doping element concentration in Ba 0.5 Sr 0.5 Ce 1− x − y − z Zr x Gd y Y z O 3−δ , revealing the improved chemical stability of Ba 0.5 Sr 0.5 Ce 0.6 Zr 0.2 Gd 0.1 Y 0.1 O 3−δ and Ba 0.5 Sr 0.5 Ce 0.5 Zr 0.3 Gd 0.1 Y 0.1 O 3−δ . Excellent chemical stability under water vapour at 90 °C for 24 h was observed for all the investigated compositions. However, extended exposure time of 168 h lead to the appearance of a small amount of Ba(OH) 2 , as observed from the powder X-ray diffraction patterns and TGA analysis after stability tests. The electrical conductivity measurements by ac impedance spectroscopy under dry and humid atmospheres revealed the proton conductivity. Among the samples investigated in this work, Ba 0.5 Sr 0.5 Ce 0.6 Zr 0.2 Gd 0.1 Y 0.1 O 3−δ (BSCZGY3) showed the highest electrical conductivity of ∼10 −3 S/cm at 700 °C in air/3% H 2 O and H 2 /3% H 2 O. [ABSTRACT FROM AUTHOR]

A new strategy is presented to immobilize the lithium polysulfides (LiPSs) and promote charge transfer kinetics at the S-electrode interface of lithium-sulfur (Li–S) batteries. In this work, biomass-derived porous carbonized pine (p-Cp), abundantly available in Canada, is used as the carbon host for S electrode in the Li–S batteries. A multifunctional composite electrocatalyst – zinc sulfide/copper sulfide (ZnS/CuS - ZCS) - is prepared through a simple chemical reaction involving successive immersion approach. The mesoporous p-Cp efficiently encapsulate the sulfur particles and provides sufficient pore volume to accommodate expansion/contraction of sulfur cathode during the charging-discharging processes. The nanostructured ZCS composite facilitates the liquid-solid phase conversion of lithium polysulfides (LiPSs) to Li 2 S to limit the LiPSs dissolution in the electrolyte. Our systematic investigation reveals that the CuS accelerates the electron transfer process while ZnS lowers the energy barrier for LiPSs redox kinetics in the composite electrode. Benefiting from the synergistic effect, the p-CpZCS/sulfur cathode achieves a high specific discharge capacity of about 1457 mAh g−1 at a rate of 0.1 C. Highly conducting biomass-based carbon, derived from pinecone incorporated with bimetallic ZnS/CuS electrocatalyst to suppress the shuttle effect. [Display omitted] • Biomass derived porous carbon loaded with ZnS/CuS nanocomposites is prepared. • The p-CpZCS-based Li–S battery reaches a high specific capacity of 1457 mAh g−1. • The phase conversion of the p-CpZCS in Li–S battery during the electrode reactions has been explored. • The presence of the CuS enhances the ability of the composite electrode to capture electrons. [ABSTRACT FROM AUTHOR]

Abstract: The effect of Ni infiltration into porous Gd-doped ceria (GDC) anodes on their H2 oxidation performance, with and without added 10 ppm H2S, is reported here. Porous GDC anodes (ca. 10 μm thick) were deposited on yttria stabilized zirconia (YSZ) supports and then infiltrated with catalytic amounts of a Ni nitrate solution, followed by electrochemical testing in a 3-electrode half-cell setup at 500–800 °C. Infiltration of 3 wt.% Ni into the porous GDC anode lowered the polarization resistance by up to 85%, affecting mainly the low frequency impedance arc. When exposed to 10 ppm H2S, the Ni-infiltrated anodes exhibited a ca. 5 times higher tolerance toward sulfur poisoning compared to GDC anodes alone, also showing excellent long-term stability in 10 ppm H2S. In the presence of H2S, it is proposed that Ni, likely distributed as a nanophase, helps to maintain a clean GDC surface at the Ni/GDC interface at which the H2 oxidation reaction takes place. In turn, the GDC will readily supply oxygen anions to the adjacent Ni surfaces, thus helping to remove adsorbed sulfur. [Copyright &y& Elsevier]

Abstract: For the first time, anodes and cathodes composed of La0.3Sr0.7Fe1–x Cr x O3–δ (LSFC, x = 0–0.3) are used within a symmetrical solid oxide fuel cell (SSOFC). La0.8Sr0.2Ga0.8Mg0.2O3–δ (LSGM) electrolyte-supported half cells, employing La0.3Sr0.7Fe0.7Cr0.3O3–δ (LSFC-3) at both electrodes, produced electrode polarization resistances of 0.1 Ω cm2 in air and 0.4 Ω cm2 in wet (ca. 3%H2O) H2 at 800 oC. Although LSFC is robust under typical SSOFC conditions at 500 oC, in-situ X-ray diffraction studies at 800 oC in reducing atmospheres show that its perovkite structure can undergo a slow, pO2-dependent structural change, forming a LaSrFeO4-based Ruddlesden-Popper phase plus α-Fe, a process which can be reversed in air at 800oC. For LSFC-3, this phase change occurs when the pO2 of the fuel is lower than 1.9 × 10−21 atm. This results in an initial power drop of ca. 30% for LSFC-3-based SSOFCs when using wet H2, but the new anode composition still maintains a promising 0.2 W cm−2 cell power density over several hundred hours of operation. Extended full cell tests also show that the LSFC-3 anode performs very well in wet 1:1 H2:CO fuels (pO2 > 1.9 × 10−21 atm) that contain 10 ppm H2S, demonstrating the excellent versatility of this electrode material. [Copyright &y& Elsevier]

The effect of Cu-substitution in Ba 0.5 Sr 0.5 Fe 1-x Cu x O 3-δ (BSFCux (0 ≤ x ≤ 0.20)) on structure and electrochemical performance was investigated using BSFCux + LSGM|LSGM|BSFCux + LSGM symmetrical cells. Powder X-ray diffraction showed that the lattice constant increased with increasing Cu in BSFCux. The effect of sintering temperature on the oxygen reduction reaction (ORR) was studied for Ba 0.5 Sr 0.5 Fe 0.95 Cu 0.05 O 3-δ + LSGM and Ba 0.5 Sr 0.5 Fe 0.8 Cu 0.2 O 3-δ + LSGM symmetrical cells. Ba 0.5 Sr 0.5 Fe 0.95 Cu 0.05 O 3-δ + LSGM showed the lowest area specific resistance (ASR) of 0.031 Ωcm2 at 800 °C in air when the cell was sintered at 1000 °C. The effect of LSGM thickness was studied on BSFCu0.05 at 1000 °C, which showed minimal effect on the ASR with electrolyte thickness (760–3110 μm). To understand the ORR mechanism of Ba 0.5 Sr 0.5 Fe 0.95 Cu 0.05 O 3-δ + LSGM and Ba 0.5 Sr 0.5 Fe 0.8 Cu 0.2 O 3-δ + LSGM, the data was analyzed using equation A S R = A S R 0 (p O 2 ) n . N values of 0 and 0.125 were obtained for Ba 0.5 Sr 0.5 Fe 0.95 Cu 0.05 O 3-δ indicative of O2− incorporation from the triple-phase-boundary (TPB) to the electrolyte and the charge transfer at the TPB as the rate determining steps for the ORR. N values of 0.35 and 0.50 were obtained for Ba 0.5 Sr 0.5 Fe 0.8 Cu 0.2 O 3-δ indicative of the dissociative charge transfer and the dissociation of adsorbed O 2 as the rate determining steps for the ORR. Image 1 • Cobalt free solid oxide fuel cell cathodes. • Chemical and electrical properties of mixed conducting perovskites. • Oxygen reduction mechanism in copper doped Ba 0.5 Sr 0.5 Fe 1-x Cu x O 3-δ (0 ≤ x ≤ 0.20). • Area specific resistance decreases with decreasing copper content. • Area specific resistance of 0.031 Ωcm2 at 800 °C for Ba 0.5 Sr 0.5 Fe 0.95 Cu 0.05 O 3-δ. [ABSTRACT FROM AUTHOR]

Fast lithium-ion conducting garnet-type metal oxides are promising membranes for next-generation all-solid-state Li batteries and beyond Li-ion batteries, including Li-air and Li-S batteries, due to their high total Li-ion conductivity and excellent chemical stability against reaction with elemental Li. Several studies have been reported on structure-chemical composition-ionic conductivity property in Li-stuffed garnet-type metal oxides. Here, an overview of the chemical and electrochemical stability of lithium-based garnets against moisture/humidity, aqueous solutions, carbon dioxide, sulfur, and metallic lithium are analyzed. Moisture and aqueous stability studies focus on understanding the crystal structure stability, the proton exchange capacity as a function of Li content in Li-stuffed garnets, and how the protonated species affect the crystal structure and mass transport properties. H + /Li + exchange was found to be in the range of 2–100%. Stability concerning Li-ion conductivity and morphology under carbon dioxide are discussed. Interfacial chemical stability with lithium metal characterized by electrochemical stability window, Li dendrite formation and area specific resistance (ASR) for the reaction L i ⇌ L i + + e − are presented. Recent attempts to suppress dendrite formation and to reduce ASR via surface modification are also highlighted. Li and Li-stuffed garnet interface ASR values are shown to be as high as >2000 Ω cm 2 and as low as 1 Ω cm 2 at room temperature for surface modified Li-stuffed samples. Furthermore, recent studies on Li-S battery utilizing chemically stable Li – garnet electrolyte are also discussed. [ABSTRACT FROM AUTHOR]

Localized high concentrations electrolyte (LHCE) has garnered significant attention as an emerging electrolyte candidate for Li-metal batteries. LHCE is formed by diluting a high concentration electrolyte (usually close to saturation) with a non-solvating solvent that has a low donor number. We propose a modified concept of LHCE, called "localized electrolyte (LE)," optimized for Li-ion batteries with a graphite anode and Ni-rich cathode. In LE, the Li salt concentration is optimized to be only 1-2 M in solvating solvents, resulting in an overall concentration of 0.5–1 M, which reduces cost and supports fast ion transport. The non-flammable LE also has excellent wettability, which facilitates fasting charging. We also demonstrated that with the addition of 2 wt.% vinylene carbonate into 0.7 M LE, the Li-ion cell retains 80.3% of its initial capacity after 700 cycles of testing in about 4 months. Overall, LE represents a promising and cost-effective solution for improving the performance and safety of Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Oxides with the nominal chemical compositions Li5La3Sb2O12 and Li6SrLa2Sb2O12 were prepared by solid-state reaction. The structures were refined by the Rietveld method using powder X-ray diffraction data. The synthesis of Li5La3Sb2O12 resulted in the well known garnet-related structure plus 5wt.% of La2LiSbO6 in the bulk. In contrast to that, Li6SrLa2Sb2O12 could be synthesised in single garnet-related type phase. Lithium ion conductivities of Li5La3Sb2O12 and Li6SrLa2Sb2O12 were studied by the ac impedance method. The grain-boundary contribution to the total (bulk+grain-boundary) resistance is very small and about 5 and 3% for Li5La3Sb2O12 and Li6SrLa2Sb2O12, respectively, at 24°C and decreases further with increase in temperature. Among the investigated compounds, Li5La3Sb2O12 exhibits the highest total (bulk+grain-boundary) and bulk ionic conductivity of 7.8×10−6 and 8.2×10−6 Scm−1, respectively, at 24°C. The structural data indicate that the coupled substitution Li+Sr⇒La leads to a closure of the bottle neck like O–O distances of the shared edges of neighbouring Li octahedra and therefore reduces the mobility of Li ions in Li6SrLa2Sb2O12. Scanning electron microscope (SEM) images of the Li6SrLa2Sb2O12 compound revealed well crystallised large homogeneous grains (∼4.8μm) and the grains were in good contact with the neighbouring grain, which leads to a smaller grain-boundary contribution to the total resistance. [Copyright &y& Elsevier]

• Li 6.5 La 2.5 Ba 0.5 TaZrO 12 electrolyte prepared at different sintering temperature. • XRD studies indicate formation of cubic phase electrolyte. • Samples synthesized at highest sintering temperature has denser structure. • 60 fold increase in ionic conductivity observed for samples sintered at 1200 °C. The garnet-type Li 6.5 La 2.5 Ba 0.5 TaZrO 12 (LLBTZO) electrolyte for Li-ion battery was synthesized by doping tantalum (Ta) and barium (Ba) in Li 7 La 3 Zr 2 O 12 (LLZO) via solid-state method at different sintering temperatures (1100, 1150 and 1200 °C). The as-prepared sintered compositions were characterized for their physical properties using X-ray diffraction (XRD) which confirmed the formation of desired cubic phase of LLBTZO. The material was further investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and He-pycnometer to study morphological and electrochemical properties. Increasing the sintering temperature from 1100 to 1200 °C led to more than 60-fold increase in the ionic conductivity at 26 °C from 1.07 × 10−6 to 6.62 × 10−5 S/cm, which can be attributed to evolution of microstructures. With increasing sintering temperature, more of the powder surface is eliminated, the density of the resulting pellet was increased, and thus the total conductivity was enhanced. [ABSTRACT FROM AUTHOR]

Ubiquitous low-cost sodium ore is abundant and increasingly of interest for sodium-based battery research for grid-scale energy storage systems. The conventional organic liquid electrolytes in currently used sodium-based batteries endure inflammability, thermal instability, and risk of safety issues. The recent trend in developing solid-state-Li batteries also thrives on exploring the all-solid-state Na battery. Herein, we report a solid-state Na-ion full cell working at room temperature using a polyvinylidene fluoride (PVDF)-based composite polymer electrolyte and NaZr 2 (PO 4) 3 -structured Na 3 V 2 (PO 4) 3 (NVP) electrode. PVDF-based composite polymer electrolyte (CPE) with NaCF 3 SO 3 salt and SiO 2 filler displays high conductivity with electrochemical stability. The symmetric solid-state full cell delivers a specific capacity of 76 mA h g−1 at 0.5C rate, and a specific energy of 126 W h kg−1 based on the total mass of the NVP cathode only. The solid-state Na-ion full cell can retain 70% of its initial specific capacity after 100 continuous charge-discharge cycles. Image 1 • Composite polymer electrolyte (CPE) with high Na-ion conductivity is prepared. • Symmetric solid-state Na-ion full cell is demonstrated with CPE and NASICON electrode. • Solid-state Na-ion full cell exhibits an energy density of 126 W h kg−1. [ABSTRACT FROM AUTHOR]