Iron oxide anode materials for rechargeable lithium-ion batteries have garnered extensive attention because of their inexpensiveness, safety, and high theoretical capacity. Nanostructured iron oxide anodes often undergo negative fading, that is, unconventional capacity increase, which results in a capacity increasing upon cycling. However, the detailed mechanism of negative fading still remains unclear, and there is no consensus on the provenance. Herein, we comprehensively investigate the negative fading of iron oxide anodes with a highly ordered mesoporous structure by utilizing advanced synchrotron-based analysis. Electrochemical and structural analyses identified that the negative fading originates from an optimization of the electrolyte-derived surface layer, and the thus formed layer significantly contributes to the structural stability of the nanostructured electrode materials, as well as their cycle stability. This work provides an insight into understanding the origin of negative fading and its influence on nanostructured anode materials.

Mesoporous transition metal dichalcogenides with 2D layered crystallinity, synthesized through a melting-infiltration assisted nano-replication, exhibit excellent electrochemical performances for lithium-storage.

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Lithiation–delithiation reactions in Li‐ion batteries do exhibit a huge electrochemically driven volume change of the anode material between the lithium‐free and lithiated‐host states, which results in a gradually fading capacity. Minimizing this volume change of the electrode during cycling is essential to achieve stable electrochemical behavior and thus for innovating design of electrode materials for Li storage. Here, ordered mesoporous CoSn intermetallic anode materials with various Co/Sn atomic ratios are developed. A dual‐buffer effect is discovered that accommodates the volume changes in the electrode material by not only repeatedly generating void nanospaces but also by incorporating electrochemically inactive elements. Novel insights into the nanostructural changes of electrode materials during the lithiation–delithiation process are obtained by in operando small angle X‐ray scattering. The degrees of volume change and nanoscopic order are found to be highly dependent on the Co contents in the mesoporous CoSn intermetallic anode materials, being possible to achieve a durable nanostructured electrode upon prolonged cycling.

Nanostructured materials make a considerable impact on the performance of lithium-storage characteristics in terms of the energy density, power density, and cycle life. Direct experimental observation, by a comparison of controlled nanostructural uniformity of electrode materials, reveals that the lithium-storage behaviors of mesoporous MoO and CuO electrodes are linearly correlated with their nanostructural uniformity. Reversible capacities of mesoporous MoO and CuO electrodes with well-developed nanostructures (1569 mA h g for MoO and 1029 mA h g for CuO) exceed their theoretical capacity based on the conversion reaction (838 mA h g for MoO and 674 mA h g for CuO). Given that exact understanding of the origin of the additional capacity is essential in maximizing the energy density of electrode material, this work may help to gain some insights into the development of high energy-density lithium-storage materials for next-generation lithium rechargeable batteries.

Highly ordered mesoporous Cd x Zn 1−x S materials were obtained via a simple nanoreplication method using a mesoporous silica template with a 3-D bicontinuous cubic Ia3d mesostructure. Combined analyses using X-ray diffraction, N 2 sorption, electron microscopy, and diffuse reflectance UV− visible spectroscopy revealed that the ordered mesoporous ternary compound semiconductor materials exhibited welldeveloped crystalline frameworks, high surface areas of 80− 120 m 2 g −1 , uniform mesopore sizes of about 20 nm, ordered arrangement of mesopores, and outstanding visible light absorption properties. Photocatalytic activities were investigated by degradation of methylene blue and rhodamine B under visible light over the mesoporous Cd x Zn 1−x S materials. Due to the high surface area and outstanding light absorption properties, the ordered mesoporous Cd x Zn 1−x S exhibited excellent photocatalytic performances for the degradation of methylene blue and rhodamine B. This study indicates a potential application of the mesoporous compound semiconductors in the efficient visiblelight-driven photolysis of organics that may cause environmental pollution.

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