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In this study we present gas-phase fluorination as a method to create a thin LiF layer on Li6.5La3Zr1.5Ta0.5O12 (LLZTO). We compared these fluorinated films with LiF films produced by RF-magnetron sputtering, where we investigated the interface between the LLZTO and the deposited LiF showing no formation of a reaction layer. Furthermore, we investigated the ability of this LiF layer as a protection layer against Li2CO3 formation in ambient air. By this, we show that Li2CO3 formation is absent at the LLZTO surface after 24 h in ambient air, supporting the protective character of the formed LiF films, and hence potentially enhancing the handling of LLZTO in air for battery production. With respect to the use within hybrid electrolytes consisting of LLZTO and a mixture of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), we also investigated the interface between the formed LiF films and a mixture of PEO+LiTFSI by X-ray photoelectron spectroscopy (XPS), showing decomposition of the LiTFSI at the interface.

In this study we present gas-phase fluorination as a method to create a thin LiF layer on Li6.5La3Zr1.5Ta0.5O12 (LLZTO). We compare these fluorinated films with LiF films produced by RF-magnetron sputtering, where we investigated the interface between the LLZTO and the deposited LiF showing no formation of a reaction layer. Furthermore, we investigate the ability of this LiF layer as a protection layer against Li2CO3 formation in ambient air. By this we show that Li2CO3 formation is absent at the LLZTO surface after 24 h in ambient air supporting the protective character of the formed LiF films and hence could enhance the handling of LLZTO in air for battery production. With respect to the use within hybrid electrolytes consisting of LLZTO and a mixture of polyethylene oxide (PEO) and Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) we also investigated the interface between the formed LiF films and a mixture of PEO LiTFSI by X-ray photoelectron spectroscopy (XPS) showing decomposition of the LiTFSI at the interface.

A new vacancy ordered, anion deficient perovskite modification with composition of BaCoO2.67 (Ba3Co3O8□1) has been prepared via a two‐step heating process. Combined Rietveld analysis of neutron and X‐ray powder diffraction data shows a novel ordering of oxygen vacancies not known before for barium cobaltates. A combination of neutron powder diffraction, magnetic measurements, and density functional theory (DFT) studies confirms G‐type antiferromagnetic ordering. From impedance measurements, the electronic conductivity of the order of 10−4 S cm−1 is determined. Remarkably, the bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is found to be comparable to that of Ba0.5Sr0.5Co0.8Fe0.2O3–y , confirming that charge‐ordered anion deficient non‐cubic perovskites can be highly efficient catalysts., A new charge ordered oxygen deficient perovskite in barium cobaltate system is reported with bifunctional catalytic activity for oxygen reduction and oxygen evolution comparable to that to that benchmark perovskite catalyst BSCF.

Within this article, it is shown that an electrochemical defluorination and additional fluorination of Ruddlesden–Popper-type La2NiO3F2 is possible within all-solid-state fluoride-ion batteries. St...

Perovskite oxides with mixed ionic and electronic conductivities are very promising candidates for their application as energy materials related to fuel cell and metal air battery integration. In this article, we report on the systematic characterization of mixed proton and electron conducting compounds of composition BaFe1−xCoxO3−y−δ(OH)y synthesized via nebulized spray pyrolysis. Independent of the value of x, all samples BaFe1−xCoxO3−y−δ(OH)y were found to crystallize in an orthorhombic ordering/distortion variant of the perovskite type structure (space group Cmcm) and are isotypic to the border phases (x = 0 or 1) reported previously. A minimum water content was observed for the composition with x = 0.5, which increases steadily for Co or Fe richer compositions. Impedance studies show that the conductivity increases with increasing Co-content, with BaCo0.5Fe0.5O2.07(OH)0.74 showing a total electrical conductivity of 10−7 S cm−1 at 298 K, an order of magnitude higher than found for BaFeO2.33(OH)0.33. Further, bifunctional catalytic activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was found for the compounds of the series as investigated in 0.1 M KOH, with BaFe0.8Co0.2O3−y−δ(OH)y possessing the best bifunctional performance parameter of ΔU = 1.10 V, which is comparable to that of other non-precious metal catalysts.

Composite electrolytes comprising a polymer plus Li salt matrix and embedded fillers have the potential of realizing high lithium-ion conductivity, good mechanical properties, wide electrochemical operational window, and stability against metallic lithium, all of which are essential for the development of high-energy-density all-solid-state lithium-ion batteries. In this study, a solvent-free approach has been used to prepare composite electrolytes with tetragonal and cubic phase garnets synthesized via nebulized spray pyrolysis with polyethylene oxide (PEO) being the polymer component. Electrochemical impedance spectroscopy (EIS) is used to examine a series of composites with different garnets and weight fractions. The results show that with the increase in the ceramic weight fraction in the composites, ionic conductivity is reduced and alternative Li-ion transport pathways become accessible for composites as compared to the filler-free electrolytes. An attempt is made to understand the ion transport mechanism within the composites. The role of the chemical and morphological properties of the ceramic filler in polymer-rich and ceramic-rich composite electrolytes is explained by studying the blends of nonconducting ceramics with the Li-conducting polymer, indicating that the intrinsic conductivity of the ceramic filler significantly contributes to the overall conductive process in the ceramic-rich systems. Further, the stability of the garnet/PEO interface is studied via X-ray photoelectron spectroscopy, and its impact on the lithium-ion transport is studied using EIS.

Communications materials 1(1), 27 (2020). doi:10.1038/s43246-020-0030-5, Fluoride ion batteries (FIBs) are a recent alternative all-solid-state battery technology. However, the FIB systems proposed so far suffer from poor cycling performance. In this work, we report La$_{2}$NiO$_{4.13}$ with a Ruddlesden-Popper type structure as an intercalation-based active cathode material in all solid-state FIB with excellent cycling performance. The critical charging conditions to maintain the conductivity of the cell were determined, which seems to be a major obstacle towards improving the cycling stability of FIBs. For optimized operating conditions, a cycle life of about 60 cycles and over 220 cycles for critical cut-off capacities of 50 mAh/g and 30 mAh/g, respectively, could be achieved, with average Coulombic efficiencies between 95 – 99%. Cycling of the cell is a result of fluorination/de-fluorination into and from the La$_{2}$NiO$_{4+d}$ cathode, and it is reve aled that La$_{2}$NiO$_{4.13}$ is a multivalent electrode material. Our findings suggest that La$_{2}$NiO$_{4.13}$ is a promising high energy cathode for FIBs., Published by Springer Nature, London

The Ruddlesden–Popper (K2NiF4) type phase La2NiO3F2 was prepared via a polymer-based fluorination of La2NiO4+d. The compound was found to crystallize in the orthorhombic space group Cccm (a = 12.8350(4) A, b = 5.7935(2) A, c = 5.4864(2) A). This structural distortion results from an ordered half occupation of the interstitial anion layers and has not been observed previously for K2NiF4-type oxyfluoride compounds. From a combination of neutron and X-ray powder diffraction and 19F magic-angle spinning NMR spectroscopy, it was found that the fluoride ions are only located on the apical anion sites, whereas the oxide ions are located on the interstitial sites. This ordering results in a weakening of the magnetic Ni–F–F–Ni superexchange interactions between the perovskite layers and a reduction of the antiferromagnetic ordering temperature to 49 K. Below 30 K, a small ferromagnetic component was found, which may be the result of a magnetic canting within the antiferromagnetic arrangement and will be the subjec...

The Ruddlesden-Popper (K