Non-aqueous lithium-air batteries represent the next-generation energy storage devices with very high theoretical capacity. The benefit of lithium-air batteries is based on the assumption that the anodic lithium is completely reversible during the discharge-charge process. Here we report our investigation on the reversibility of the anodic lithium inside of an operating lithium-air battery using spatially and temporally resolved synchrotron X-ray diffraction and three-dimensional micro-tomography technique. A combined electrochemical process is found, consisting of a partial recovery of lithium metal during the charging cycle and a constant accumulation of lithium hydroxide under both charging and discharging conditions. A lithium hydroxide layer forms on the anode separating the lithium metal from the separator. However, numerous microscopic 'tunnels' are also found within the hydroxide layer that provide a pathway to connect the metallic lithium with the electrolyte, enabling sustained iontransport and battery operation until the total consumption of lithium.

When a stress is applied on a metallic glass it deforms following Hook's law. Therefore it may appear obvious that a metallic glass deforms elastically. Using x-ray diffraction and anisotropic pair-density function analysis we show that only about 3/4 in volume fraction of metallic glasses deforms elastically, whereas the rest of the volume is anelastic and in the experimental time scale deform without resistance. We suggest that this anelastic portion represents residual liquidity in the glassy state. Many theories, such as the free-volume theory, assume the density of defects in the glassy state to be of the order of 1%, but this result shows that it is as much as a quarter.

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During plastic deformation of metals and alloys, dislocations arrange in ordered patterns. How and when these self-organization processes take place have remained elusive, because in situ observations have not been feasible. We present an x-ray diffraction method that provided data on the dynamics of individual, deeply embedded dislocation structures. During tensile deformation of pure copper, dislocation-free regions were identified. They showed an unexpected intermittent dynamics, for example, appearing and disappearing with proceeding deformation and even displaying transient splitting behavior. Insight into these processes is relevant for an understanding of the strength and work-hardening of deformed materials.

The suspension plasma spray (SPS) process was used to produce coatings from yttria-stabilized zirconia (YSZ) powders with median diameters of 15 lm and 80 nm. The powder-ethanol suspensions made with 15-lm diameter YSZ particles formed coatings with microstructures typical of the air plasma spray (APS) process, while suspensions made with 80-nm diameter YSZ powder yielded a coarse columnar microstructure not observed in APS coatings. To explain the formation mechanisms of these different microstructures, a hypothesis is presented which relates the dependence of YSZ droplet flight paths on droplet diameter to variations in deposition behavior. The thermal conductivity (k th ) of columnar SPS coatings was measured as a function of temperature in the as-sprayed condition and after a 50 h, 1200°C heat treatment. Coatings produced from suspensions containing 80 nm YSZ particles at powder concentrations of 2, 8, and 11 wt.% exhibited significantly different k th values. These differences are connected to microstructural variations between the SPS coatings produced by the three suspension formulations. Heat treatment increased the k th of the coatings generated from suspensions containing 2 and 11 wt.% of 80 nm YSZ powder, but this k th increase was less than has been observed in APS coatings.