Suppressing the Sn coarsening in the Li2O matrix enabled highly reversible conversion between Li2O and SnO2 and an initial Coulombic efficiency of ∼95.5% was achieved.

A facile hydrothermal method is utilized to produce nanostructured NiCo 2 S 4 arrays on carbon fiber paper with controlled morphologies to study the effect of morphology on their electrochemical performance in supercapacitors. Specifically, NiCo 2 S 4 solid nanofiber, nanotube, and hollow nanoneedle of the same crystalline structure are synthesized by controlling the conditions of the hydrothermal synthesis. Among the three different morphologies studied, the hollow nanoneedle of NiCo 2 S 4 shows the highest capacity and the longest cycling life, demonstrating a specific capacitance of ~1154 F g-1 at a charge-discharge current density of 1 A g-1 and negligible capacity loss after 8,000 cycles (at a rate of 10 A g-1). This high performance is attributed to the unique nanostructure of the hollow nanoneedle, suggesting that the morphology of NiCo 2 S 4 plays a vital role in determining the electrochemical performance. Further, an asymmetric capacitor consisting of NiCo 2 S 4 hollow nanoneedle electrode and a tape-cast activated carbon film electrode achieves an energy density of ~17.3 Wh kg-1 at 1 A g-1 and a power density of ~3.2 kW kg-1 at 20 A g-1 in a voltage range of 0 and 1.5 V, implying that it has a great potential for a wide variety of practical applications.

Hollow nanofibers of PrBa 0.5 Sr 0.5 Co 2 O 5+δ (PBSC), created by an electrospinning process, are assembled into a three dimensional (3D) fibrous porous electrode, providing facile pathways for gas transport and excellent electrical conductivity for efficient charge transfer and, thus, greatly enhancing the rate of oxygen reduction reactions (ORR), as confirmed by the small electrode polarization resistance and low activation energy. A simple geometric modelling suggests that an electrode with longer fibers tends to be more efficient in facilitating mass and charge transfer under the conditions studied. A solid oxide fuel cell based on this 3D fibrous cathode demonstrates a peak power density of 1.11 W cm-2 at 550 o C when humidified H 2 was used as