We demonstrate the newly developed Si-based multicomponent anodes exhibiting a highly stable cycling retention (∼65% after 1000 cycles at a 1 C discharge–charge rate).

Crack assessment is an essential process in the maintenance of concrete structures. In general, concrete cracks are inspected by manual visual observation of the surface, which is intrinsically subjective as it depends on the experience of inspectors. Further, it is time-consuming, expensive, and often unsafe when inaccessible structural members are to be assessed. Unmanned aerial vehicle (UAV) technologies combined with digital image processing have recently been applied to crack assessment to overcome the drawbacks of manual visual inspection. However, identification of crack information in terms of width and length has not been fully explored in the UAV-based applications, because of the absence of distance measurement and tailored image processing. This paper presents a crack identification strategy that combines hybrid image processing with UAV technology. Equipped with a camera, an ultrasonic displacement sensor, and a WiFi module, the system provides the image of cracks and the associated working distance from a target structure on demand. The obtained information is subsequently processed by hybrid image binarization to estimate the crack width accurately while minimizing the loss of the crack length information. The proposed system has shown to successfully measure cracks thicker than 0.1 mm with the maximum length estimation error of 7.3%.

In concrete structures, surface cracks are important indicators of structural durability and serviceability. Generally, concrete cracks are visually monitored by inspectors who record crack information such as the existence, location, and width. Manual visual inspection is often considered ineffective in terms of cost, safety, assessment accuracy, and reliability. Digital image processing has been introduced to more accurately obtain crack information from images. A critical challenge is to automatically identify cracks from an image containing actual cracks and crack-like noise patterns (e.g. dark shadows, stains, lumps, and holes), which are often seen in concrete structures. This article presents a methodology for identifying concrete cracks using machine learning. The method helps in determining the existence and location of cracks from surface images. The proposed approach is particularly designed for classifying cracks and noncrack noise patterns that are otherwise difficult to distinguish using existing image processing algorithms. In the training stage of the proposed approach, image binarization is used to extract crack candidate regions; subsequently, classification models are constructed based on speeded-up robust features and convolutional neural network. The obtained crack identification methods are quantitatively and qualitatively compared using new concrete surface images containing cracks and noncracks.

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Stretchable electronics are considered as next‐generation devices; however, to realize stretchable electronics, it is first necessary to develop a deformable energy device. Of the various components in energy devices, the fabrication of stretchable current collectors is crucial because they must be mechanically robust and have high electrical conductivity under deformation. In this study, the authors present a conductive polymer composite composed of Jabuticaba‐like hybrid carbon fillers containing carbon nanotubes and carbon black in a simple solution process. The hybrid carbon/polymer (HCP) composite is found to effectively retain its electrical conductivity, even when under high strain of ≈200%. To understand the behavior of conductive fillers in the polymer matrix when under mechanical strain, the authors investigate the microstructure of the composite using an in situ small‐angle X‐ray scattering analysis. The authors observe that the HCP produces efficient electrical pathways for filler interconnections upon stretching. The authors develop a stretchable aqueous rechargeable lithium‐ion battery (ARLB) that utilizes this HCP composite as a stretchable current collector. The ARLB exhibits excellent rate capability (≈90 mA h g−1 at a rate of 20 C) and outstanding capacity retention of 93% after 500 cycles. Moreover, the stretchable ARLB is able to efficiently deliver power even when under 100% strain.

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LIBs), stretchable supercapacitors, and stretchable silver-zinc batteries. [5][6][7][8] Most of them mainly focused on the development of deformable current collectors (e.g., embedding conductive materials in soft substrates or elastic substrates) [9,10] or structural layouts (e.g., helically coiled spring design, serpentine interconnected configuration, and origami structure). [11][12][13] In comparison, a stretchable separator membrane for deformable energystorage devices attracts little attention. The separator membrane is basically used to prevent physical and electrical contact between electrodes while offering an ion conduction channel. [14] Various types of stretchable batteries are being developed, and thus the stretchable properties of the separator membrane are also required. Generally, because ionic gel-polymer electrolytes (GPEs) are easily controllable and sufficiently deformable, they have been employed as the separator membrane in deformable energy-storage devices. [13,15,16] Although ion-conducting GPEs can be used as both electrolyte and separator, they have intrinsically lower ionic conductivity than liquid electrolytes [17] and poor mechanical properties which are likely to cause an internal short problem due to the contact of both electrodes under physical deformation. [18,19] In order to fabricate a reliable stretchable energy-storage device without these limitations, the presence of a physical separation barrier having an ion-conducting channel and stretchability is essential. Recently, Liu et al. reported a stretchable separator membrane for wavy-structured stretchable LIBs using electrospinning techniques. [20] Li et al. also used electrospinning process to fabricate a stretchable polyurethane separator for stretchable supercapacitor. [21] However, electrospinning has critical drawbacks such as the use of complex equipment, slow production rate, and possible toxicity of chemical residues in electrospun fibers. Moreover, it has the limitation for largescale production for industry level due to its high cost. [22,23] Given these limitations, it is still necessary to develop and improve the fabrication methodologies for stretchable separator membranes. Although various attempts have been made in the membrane component to achieve the complete stretchability of the battery, the development of the standardized separator membrane that can be applied to various types of stretchable battery has not yet been reported. Therefore, the development of stretchable separator membranes with high processibility With the emergence of stretchable electronic devices, there is growing interest in the development of deformable power accessories that can power them. To date, various approaches have been reported for replacing rigid components of typical batteries with elastic materials. Little attention, however, has been paid to stretchable separator membranes that can not only prevent internal short circuit but also provide an ionic conducting pathway between electrodes under extreme physical deformation. Herei...

Three-dimensional (3D) hyperporous silicon flakes (HPSFs) are prepared via the chemical reduction of natural clay minerals bearing metal oxides. Natural clays generally have 2D flake-like structures with broad size distributions in the lateral dimension and varied thicknesses depending on the first processing condition from nature. They have repeating layers of silicate and metal oxides in various ratios. When the clay mineral is subjected to a reduction reaction, metal oxide layers can perform a negative catalyst for absorbing large amounts of exothermic heat from the reduction reaction of the silicate layers with metal reductant. Selectively etching out metal oxides shows a hyperporous nanoflake structure containing 100 nm macropores and meso-/micropores on its framework. The resultant HPSFs are demonstrated as anode materials for lithium-ion batteries. Compared to conventional micro-Si anodes, HPSFs exhibit exceptionally high initial Coulombic efficiency over 92%. Furthermore, HPSF anodes show outstanding cycling performance (reversible capacity of 1619 mAh g at a rate of 0.5 C after 200 cycles, 95.2% retention) and rate performance (∼580 mAh g at a rate of 10 C) owing to their distinctive structure.