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Type: Article × Type: Text × Publisher: Washington, DC : ACS Publications × WGL Institute: INM ×

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Now showing 1 - 3 of 3
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    Mixed Cu-Fe Sulfides Derived from Polydopamine-Coated Prussian Blue Analogue as a Lithium-Ion Battery Electrode
    (Washington, DC : ACS Publications, 2022) Bornamehr, Behnoosh; Presser, Volker; Husmann, Samantha
    Batteries employing transition-metal sulfides enable high-charge storage capacities, but polysulfide shuttling and volume expansion cause structural disintegration and early capacity fading. The design of heterostructures combining metal sulfides and carbon with an optimized morphology can effectively address these issues. Our work introduces dopamine-coated copper Prussian blue (CuPB) analogue as a template to prepare nanostructured mixed copper-iron sulfide electrodes. The material was prepared by coprecipitation of CuPB with in situ dopamine polymerization, followed by thermal sulfidation. Dopamine controls the particle size and favors K-rich CuPB due to its polymerization mechanism. While the presence of the coating prevents particle agglomeration during thermal sulfidation, its thickness demonstrates a key effect on the electrochemical performance of the derived sulfides. After a two-step activation process during cycling, the C-coated KCuFeS2electrodes showed capacities up to 800 mAh/g at 10 mA/g with nearly 100% capacity recovery after rate handling and a capacity of 380 mAh/g at 250 mA/g after 500 cycles.
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    Templated Self-Assembly of Ultrathin Gold Nanowires by Nanoimprinting for Transparent Flexible Electronics
    (Washington, DC : ACS Publications, 2016) Maurer, Johannes H. M.; González-García, Lola; Reiser, Beate; Kanelidis, Ioannis; Kraus, Tobias
    We fabricated flexible, transparent, and conductive metal grids as transparent conductive materials (TCM) with adjustable properties by direct nanoimprinting of self-assembling colloidal metal nanowires. Ultrathin gold nanowires (diameter below 2 nm) with high mechanical flexibility were confined in a stamp and readily adapted to its features. During drying, the wires self-assembled into dense bundles that percolated throughout the stamp. The high aspect ratio and the bundling yielded continuous, hierarchical superstructures that connected the entire mesh even at low gold contents. A soft sintering step removed the ligand barriers but retained the imprinted structure. The material exhibited high conductivities (sheet resistances down to 29 Ω/sq) and transparencies that could be tuned by changing wire concentration and stamp geometry. We obtained TCMs that are suitable for applications such as touch screens. Mechanical bending tests showed a much higher bending resistance than commercial ITO: conductivity dropped by only 5.6% after 450 bending cycles at a bending radius of 5 mm.
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    Preventing Catastrophic Failure of Microfibrillar Adhesives in Compliant Systems Based on Statistical Analysis of Adhesive Strength
    (Washington, DC : ACS Publications, 2021) Hensel, René; Thiemecke, Jonathan; Booth, Jamie A.
    Adhesives based on fibrillar surface microstructures have shown great potential for handling applications requiring strong, reversible, and switchable adhesion. Recently, the importance of the statistical distribution of adhesive strength of individual fibrils in controlling the overall performance was revealed. Strength variations physically correspond to different interfacial defect sizes, which, among other factors, are related to surface roughness. For analysis of the strength distribution, Weibull's statistical theory of fracture was introduced. In this study, the importance of the statistical properties in controlling the stability of attachment is explored. Considering the compliance of the loading system, we develop a stability criterion based on the Weibull statistical parameters. It is shown that when the distribution in fibril adhesive strength is narrow, the global strength is higher but unstable detachment is more likely. Experimental variation of the loading system compliance for a specimen of differing statistical properties shows a transition to unstable detachment at low system stiffness, in good agreement with the theoretical stability map. This map serves to inform the design of gripper compliance, when coupled with statistical analysis of strength on the target surface of interest. Such a treatment could prevent catastrophic failure by spontaneous detachment of an object from an adhesive gripper. © 2021 The Authors. Published by American Chemical Society.