The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at <mml:math display="inline"><mml:mrow><mml:mn>850</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>850°C , at current densities of −1.0, −1.5, and <mml:math display="inline"><mml:mrow><mml:mo>−</mml:mo><mml:mn>2.0</mml:mn><mml:mspace width="0.5em"></mml:mspace><mml:mi mathvariant="normal">A</mml:mi><mml:mo>/</mml:mo><mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>−2.0A/cm2 , with a 50:50 <mml:math display="inline"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mo>:</mml:mo><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>(H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode and oxygen supplied to the lanthanum, strontium manganite (LSM)/YSZ oxygen electrode. Electrode polarization resistance degradation is not directly related to the applied current density but rather a consequence of adsorbed impurities in the Ni/YSZ hydrogen electrode. However, the ohmic resistance degradation increases with applied current density. The ohmic resistance degradation is attributed to oxygen formation in the YSZ electrolyte grain boundaries near the oxygen electrode/electrolyte interface.

Lithium sulfur battery (LSB) research has received considerable attention due to the high theoretical gravimetric energy density of LSBs. However, in practice, the active sulfur material needs to be coupled with a conducting material due to its poor electronic conductivity (5 × 10⁻³⁰ S cm⁻¹) – reducing the battery energy density. Furthermore, lithium polysulfides (PSs), formed as soluble intermediate phases, can shuttle between the cathode and the anode – leading to rapid capacity degradation. Coating the traditional separators is one way to mitigate the shuttle effect which requires proper understanding of the nature of PSs to design effective separator coating materials. In this review, the technical limitations of LSBs are introduced with detailed information about the PS dimensions. Subsequently, carbon, polymer and inorganic coating materials have been highlighted with their significant contributions to the performance of LSBs. A particular focus has been placed on their mechanisms of trapping PSs through polar–polar, Lewis acid–base interactions and physical confinement. Finally, the key factors which influence the performances of LSBs are summarized.

Reduction of H₂O and CO₂ as well as oxidation of H₂ and CO was studied in a Ni/YSZ electrode supported Solid Oxide Cell (SOC) produced at DTU Energy conversion (former Risø DTU). Even though these Ni/YSZ based SOCs were developed and optimized for fuel cell use, they can work as reversible SOCs in mixtures of H₂O, H₂, CO₂ and CO. From polarization (i-V) and electrochemical impedance spectroscopic characterization, it is evident that, electrochemical reduction of both CO₂ and H₂O occurs during co-electrolysis of H₂O and CO₂ in these Ni/YSZ based SOC. During co-electrolysis, the equilibrium of the water gas shift reaction is reached, and CO is therefore produced via the water gas shift reaction also. Significant differences during oxidation/reduction in H₂O – H₂ and CO₂ – CO mixtures were observed implying that different reaction mechanisms apply for the mixtures.