Käfigtransport: Die Aufnahme von H2‐Molekülen in H2O‐Käfige unter Bildung von Wasserstoff‐Clathrat‐Hydraten eröffnet neue Möglichkeiten für die Speicherung und den Transport von Wasserstoff. Reine H2‐Cluster lassen sich jedoch nur unter hohem Druck im Clathrat‐Hydrat stabilisieren. Abhilfe schafft die Einführung von THF als zweitem Gastmolekül, das den erforderlichen Druck von 220 MPa auf 5 MPa verringert (Bild: H2/THF‐Hydrat; blau THF, rot H2).

Nano-composite Sm(0.5)Sr(0.5)CoO(3-δ) (SSC)-Ce(0.9)Gd(0.1)O(1.95) (GDC) and La(0.6)Sr(0.4)Co(0.8)Fe(0.2)O(3-δ) (LSCF)-GDC Solid Oxide Fuel Cell (SOFC) cathodes with various infiltrate loading levels were prepared through multiple nitrate solution infiltrations into porous GDC ionic conducting (IC) scaffolds. Microstructural analyses indicated that the average SSC and average LSCF hemispherical particle radii remained roughly constant, at 25 nm, across multiple infiltration-gelation-firing sequences. Comparisons between symmetric cell polarization resistance measurements and Simple Infiltrated Microstructure Polarization Loss Estimation (SIMPLE) model predictions showed that the SIMPLE model was able to predict the performance of heavily infiltrated SSC-GDC and LSCF-GDC cathodes with accuracies better than 55% and 70%, respectively (without the use of fitting parameters). Poor electronic conduction between mixed ionic electronic conducting (MIEC) infiltrate particles was found in lightly infiltrated cathodes. Since these electronic conduction losses were not accounted for by the SIMPLE model, larger discrepancies between the SIMPLE-model-predicted and measured polarization resistances were observed for lightly infiltrated cathodes. This work demonstrates that the SIMPLE model can be used to quickly determine the lowest possible polarization resistance of a variety of infiltrated MIEC on IC nano-composite cathodes (NCC's) when the NCC microstructure and an experimentally-applicable set of intrinsic MIEC oxygen surface resistances and IC bulk oxygen conductivities are known. Currently, this model is the only one capable of predicting the polarization resistance of heavily infiltrated MIEC on IC NCC's as a function of temperature, cathode thickness, nano-particle size, porosity, and composition.

Oxygen electrodes have been able to meet area specific resistance targets for solid oxide cell operating temperatures as low as ∼500 °C, but their stability over expected device operation times of up to 50 000 h is unknown. Achieving good performance at such temperatures requires mixed ionically and electronically-conducting electrodes with nano-scale structure that makes the electrode susceptible to particle coarsening and, as a result, electrode resistance degradation. Here we describe accelerated life testing of nanostructured Sm0.5Sr0.5CoO3-Ce0.9Gd0.1O2 electrodes combining impedance spectroscopy and microstructural evaluation. Measured electrochemical performance degradation is accurately fitted using a coarsening model that is then used to predict cell operating conditions where required performance and long-term stability are both achieved. A new electrode material figure of merit based on both performance and stability metrics is proposed. An implication is that cation diffusion, which determines the coarsening rate, must be considered along with oxygen transport kinetics in the selection of optimal electrode materials.