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Ende der achtziger Jahre hat sich angesichts der wachsenden Umweltprobleme die Forderung nach einer umweltorientierten Produktgestaltung durchgesetzt. Unternehmen haben eine Verantwortung für den gesamten Lebensweg der Produkte; diese sollen möglichst im Kreislauf geführt werden. Sind Konzepte zur Nutzungsintensivierung und Lebensdauerverlängerung eine geeignete Strategie? Anhand zweier Fallbeispiele werden Potentiale und Grenzen aufgezeigt

3-point measurement in solid state devices: (Novel) artifacts and how to avoid them

There are two common methods to measure the impedance response of only one electrode of a solid-state electrochemical cell, microelectrodes or a three-terminal configuration. In aqueous electrochemistry, three-terminal configurations are widely used, however, implementing this method in solid-state electrochemistry is highly non-trivial. This work summarizes, which method is most suitable for different applications. We show potential error sources and evaluate each of them quantitatively with special emphasis on their impact in thin film electrode measurements. Evaluation is done by means of finite elements analysis (FEA), electric circuit simulations and conducted measurements. Three potential error sources were identified as particularly crucial factors: (i) Asymmetric sample cells (ii) short circuit currents across the reference electrode (RE), (iii) Especially for highly resistive electrode, coupling capacitances between the three electrodes. These error sources can result in different measurement errors such as additional high frequency semicircles, additional low frequency semicircles, inductive loops and even more critical, erroneous electrode properties without indicating of additional features in the impedance spectrum. We propose a novel sample geometry, the “wing geometry”, which was designed to minimize the measurement errors significantly, but still remains affordable and suitable for different applications

Li+/H+ exchange of Li7La3Zr2O12 single and polycrystals investigated by quantitative LIBS depth profiling

Li7La3Zr2O12 (LLZO) garnets are highly attractive to be used as solid electrolyte in solid-state Li batteries. However, LLZO suffers from chemical interaction with air and humidity, causing Li+/H+ exchange with detrimental implication on its performance, processing and scalability. To better understand the kinetics of the detrimental Li+/H+ exchange and its dependence on microstructural features, accelerated Li+/H+ exchange experiments were performed on single crystalline and polycrystalline LLZO, exposed for 80 minutes to 80 °C hot water. The resulting chemical changes were quantified by analytical methods, i.e. inductively coupled plasma optical emission spectroscopy (ICP-OES) and laser induced breakdown spectroscopy (LIBS). From the time dependence of the Li+ enrichment in the water, measured by ICP-OES, a bulk interdiffusion coefficient of Li+/H+ could be determined (7 × 10−17 m2 s−1 at 80 °C). Depth dependent concentrations were obtained from the LIBS data for both ions after establishing a calibration method enabling not only Li+ but also H+ quantification in the solid electrolyte. Short interdiffusion lengths in the 1 μm range are found for the single crystalline Ga:LLZO, in accordance with the measured bulk diffusion coefficient. In polycrystalline Ta:LLZO, however, very long diffusion tails in the 20 μm range and ion exchange fractions up to about 70% are observed. Those are attributed to fast ion interdiffusion along grain boundaries. The severe compositional changes also strongly affect the electrical properties measured by impedance spectroscopy. This study highlights that microstructural effects may be decisive for the Li+/H+ ion exchange kinetics of LLZO

Strain-induced structure and oxygen transport interactions in epitaxial La 0.6 Sr 0.4 CoO 3− δ thin films

Abstract: The possibility to control oxygen transport in one of the most promising solid oxide fuel cell cathode materials, La0.6Sr0.4CoO3−δ, by controlling lattice strain raises questions regarding the contribution of atomic scale effects. Here, high-resolution transmission electron microscopy revealed the different atomic structures in La0.6Sr0.4CoO3−δ thin films grown under tensile and compressive strain conditions. The atomic structure of the tensile-strained film indicated significant local concentration of the oxygen vacancies, with the average value of the oxygen non-stoichiometry being much larger than for the compressive-strained film. In addition to the vacancy concentration differences that are measured by isotope exchange depth profiling, significant vacancy ordering was found in tensile-strained films. This understanding might be useful for tuning the atomic structure of La0.6Sr0.4CoO3−δ thin films to optimize cathode performance

Author Correction: Strain-induced structure and oxygen transport interactions in epitaxial La 0.6 Sr 0.4 CoO 3−δ thin films

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Dislocation‐tuned electrical conductivity in solid electrolytes (9YSZ): A micro‐mechanical approach

Tailoring the electrical conductivity of functional ceramics by introducing dislocations is a comparatively recent research focus, and its merits were demonstrated through mechanical means. Especially bulk deformation at high temperatures is suggested to be a promising method to introduce a high dislocation density. So far, however, controlling dislocation generation and their annihilation remains difficult. Although deforming ceramics generate dislocations on multiple length scales, dislocation annihilation at the same time appears to be the bottleneck to use the full potential of dislocations‐tailoring the electrical conductivity. Here, we demonstrate the control over these aspects using a micromechanical approach on yttria‐stabilized zirconia ‐ YSZ. Targeted indentation well below the dislocation annihilation temperature resulted in extremely dense dislocation networks, visualized by chemical etching and electron channeling contrast imaging. Microcontact‐impedance measurements helped evaluate the electrical response of operating individual slip systems. A significant conductivity enhancement is revealed in dislocation‐rich regions compared to pristine ones in fully stabilized YSZ. This enhancement is mainly attributed to oxygen ionic conductivity. Thus, the possibility of increasing the conductivity is illustrated and provides a prospect to transfer the merits of dislocation‐tuned electrical conductivity to solid oxygen electrolytes

A Guideline to Mitigate Interfacial Degradation Processes in Solid-State Batteries Caused by Cross Diffusion

Diffusion of transition metals across the cathode–electrolyte interface is identified as a key challenge for the practical realization of solid-state batteries. This is related to the formation of highly resistive interphases impeding the charge transport across the materials. Herein, the hypothesis that formation of interphases is associated with the incorporation of Co into the Li7La3Zr2O12 lattice representing the starting point of a cascade of degradation processes is investigated. It is shown that Co incorporates into the garnet structure preferably four-fold coordinated as Co2+ or Co3+ depending on oxygen fugacity. The solubility limit of Co is determined to be around 0.16 per formula unit, whereby concentrations beyond this limit causes a cubic-to-tetragonal phase transition. Moreover, the temperature-dependent Co diffusion coefficient is determined, for example, D700 °C = 9.46 × 10−14 cm2 s−1 and an activation energy Ea = 1.65 eV, suggesting that detrimental cross diffusion will take place at any relevant process condition. Additionally, the optimal protective Al2O3 coating thickness for relevant temperatures is studied, which allows to create a process diagram to mitigate any degradation with a minimum compromise on electrochemical performance. This study provides a tool to optimize processing conditions toward developing high energy density solid-state batteriesD.R. acknowledges financial support by the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology, and Development, and the Christian Doppler Research Association (Christian Doppler Laboratory for Solid-State Batteries). D.R. and J.F. acknowledges financial support by the Austrian Science Fund (FWF) in the frame of the project InterBatt (P 31437). D.K. acknowledges funding by the European Union’s Horizon 2020 Research and Innovation Programme (Grant No. 823717, project “ESTEEM3”) and by the Zukunftsfond Steiermark. J.G.S. and D.J.S. acknowledge financial support from the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy , Office of Science, Basic Energy Sciences. Technical assistance of M. Stypa in crystal growth experiments is greatly acknowledge