Nanostructuring of electrode materials is a promising approach to enhance the performance of next-generation, high-energy density lithium (Li)-ion batteries. Various experimental and theoretical approaches allow for a detailed understanding of solid-state or surface-controlled reactions that occur in nanoscaled electrode materials. While most techniques which are suitable for nanomaterial investigations are restricted to analysis widths of the order of Å to some nm, they do not allow for characterization over the length scales of interest for electrode design, which is typically in the order of mm. In this work, three different self-organized anodic titania nanotube arrays, comprising as-grown amorphous titania nanotubes, carburized anatase titania nanotubes, and silicon coated carburized anatase titania nanotubes, have been synthesized and studied as model composite anodes for use in Li-ion batteries. Their 2D areal Li densities have been successfully reconstructed with a sub-millimeter spatial resolution over lateral electrode dimensions of 20 mm exploiting the Li(n,α)H reaction, in spite of the extremely small areal Li densities (10-20 μg cm Li) in the nanotubular active material. While the average areal Li densities recorded via triton analysis are found to be in good agreement with the electrochemically measured charges during lithiation, triton analysis revealed, for certain nanotube arrays, areas with a significantly higher Li content ('hot spots') compared to the average. In summary, the presented technique is shown to be extremely well suited for analysis of the lithiation behavior of nanostructured electrode materials with very low Li concentrations. Furthermore, identification of lithiation anomalies is easily possible, which allows for fundamental studies and thus for further advancement of nanostructured Li-ion battery electrodes.

Silicon is considered as one of the most promising electrode materials for next‐generation, high‐energy‐density Li‐ion batteries as it demonstrates an exceptionally high specific capacity an order of magnitude beyond that of conventional graphite. The poor capacity retention, caused by the mechanical fracturing of Si because of the extreme volumetric and structural changes upon Li insertion/extraction, has triggered significant attention in the development of Si‐coated nanostructures that can accommodate the lithiation‐induced strain. In parallel, various spectroscopic studies and simulations have been conducted to understand the details of volumetric expansion, fracture, mechanical stress evolution, and structural changes in Si‐coated nanostructures. This publication reports a systematic lithiation/delithiation study of Si‐coated, anodically grown, self‐organized TiO2 nanotubes with different Si‐layer thicknesses. It is demonstrated for the first time that a “sweet spot” for the Si‐coating thickness is formed at which the specific lithiation capacity of the composite material reaches its maximum, which declines quickly for higher coating thicknesses. Furthermore, our results suggest that such a Si‐thickness‐dependent optimum in the specific lithiation capacity is immanent to any Si‐coated nanostructured electrode.

The combination of a very high lithium sensitivity with position resolving measurement makes this method well suited for postmortem studies of the microscopic lithium distribution in the human brain and thus to form a microscopic picture of the impact of lithium in different areas of the human brain.

Lithium‐Ion Batteries: The cover art depicts positive lithium ions that flow towards the silicon nanoparticles, where these nanoparticles expand during the lithiation process. Silicon has attracted great attention as a promising anode material for lithium‐ion batteries due to its exceptionally high theoretical specific capacity. Despite these promising properties, bulk silicon anodes face significant challenges due to the large volume changes upon lithiation, leading to mechanical fracturing of the active material, accumulation of solid–electrolyte interphase (SEI) layers, and rapid capacity fading during electrochemical cycling. Only recently has nanotechnology achieved a breakthrough to overcome the above‐mentioned challenges of silicon, serving as an anode electrode for lithium‐ion batteries. This collaborative work performed by Dr. Engelbert Portenkirchner Leopold‐Franzens‐University Innsbruck and his co‐authors details the correlation between the silicon coating thickness, morphological characteristics, and electrochemical lithium storage performance in silicon‐coated titanium dioxide nanotubes. More details can be found in the Full Paper by Andrea Auer et al. on page 2253 in Issue 12, 2017 (10.1002/ente.201700306).