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Jinhyup Han Jehee Park Seong-Min Bak Seoung-Bum Son Jihyeon Gim Cesar Villa Xiaobing Hu Vinayak P. Dravid Chi Cheung Su Youngsik Kim Christopher Johnson Eungje Lee 《Advanced functional materials》2021,31(2):2005362
This paper describes a new, high-performance, Pb-based nanocomposite anode material for lithium-ion batteries. A unique nanocomposite structure of Pb@PbO core-shell nanoparticles in a carbon matrix is obtained by using a simple high-energy ball milling method using the low-cost starting materials PbO and carbon black. Electrochemical performance tests show its excellent reversible capacity (≈600 mAh g−1) and cycle stability (92% retention at 100th cycle), which are one of the best values reported for Pb-based anodes in the literature. Synchrotron X-ray diffraction and absorption techniques revealed the detailed lithium storage mechanism that can be highlighted with the unexpectedly wide reversible Pb redox range (between Pb2+ and Pb4−) and the evolution of Zintl-type LiyPb structures during the electrochemical lithium reaction. The results provide new insights into the lithium storage mechanism of these Pb-based materials and their potential as low-cost, high-performance anodes. 相似文献
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Jong-Soo Cho Kyung-Ah Yoo Jeong-Tak Moon Seoung-Bum Son Se-Hee Lee Kyu Hwan Oh 《Metals and Materials International》2012,18(5):881-885
We investigated the effect of Pd concentration in Pd-doped Ag wires on the humidity reliability and interfacial corrosion characteristics between Ag wire and Al metallization. Additionally, we confirmed no corrosion problem between Ag wire and noble metal (Pd, Au) metallization, even after a pressure cooker test (PCT). The chemical composition of the tested Ag wires was pure Ag, Ag-1wt% Pd and Ag-3wt% Pd. These wires were bonded to Al and noble metal (Au, Pd) metallization using a thermo-sonic bonder. The interfaces were characterized by focused ion beam (FIB), high resolution transmission electron microscope (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The interface corrosion of Pd doped Ag wires was significantly reduced as the Pd concentration in the Ag wires increased. Furthermore, the Ag wires on the noble metal (Au, Pd) metallization exhibited stable reliability during the PCT. 相似文献
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Zheng Zhang Daniela Molina Piper Seoung-Bum Son Seul Cham Kim Kyu Hwan Oh Se-Hee Lee Yifu Ding 《Polymer》2013
We present the fabrication of lithographically defined carbon patterns and nanoribbons using a common carbon precursor, polyacrylonitrile (PAN). This method is based on nanoimprint lithography and has been demonstrated to be reliable and capable of nanofabrication over a large surface area at low cost, compared with current carbon-patterning techniques. Most interestingly, the deformation profile of the PAN during the imprinting process resulted in a distribution of aligned PAN chains within the patterns, which led to a similar anisotropic correlation of the carbon crystallites in the carbonized structures. 相似文献
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Hotspots represent transient but highly congested regions in wireless ad hoc networks that result in increased packet loss, end-to-end delay, and out-of-order packets delivery. We present a simple, effective, and scalable hotspot mitigation protocol (HMP) where mobile nodes independently monitor local buffer occupancy, packet loss, and MAC contention and delay conditions, and take local actions in response to the emergence of hotspots, such as, suppressing new route requests and rate controlling TCP flows. We use analysis, simulation, and experimental results from a wireless testbed to demonstrate the effectiveness of HMP in mobile ad hoc networks. HMP balances resource consumption among neighboring nodes, and improves end-to-end throughput, delay, and packet loss. Our results indicate that HMP can also improve the network connectivity preventing premature network partitions. We present analysis of hotspots, and the detailed design of HMP. We evaluate the protocol’s ability to effectively mitigate hotspots in mobile ad hoc networks that are based on on-demand and proactive routing protocols. 相似文献
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Carbonaceous materials have dominated lithium-ion battery anodes since their discovery in 1972. Materials and design challenges have prevented the move to silicon-based anodes, despite their significantly higher specific energies. Morphological design motifs have focused on minimizing the structural instabilities that arise during lithium insertion and removal, which are themselves the subject of numerous articles and reviews. This review focuses on surface modification techniques that have been developed to minimize volume expansion, stabilize the surface of silicon against electrical isolation following pulverization, and improve the electronic and ionic conductivities of silicon anodes during operation and cycling. 相似文献
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Seoung-Bum Son Hyunchul Roh Suk Hoon Kang Hee-Suk Chung Do Hyun Kim Yong Seok Choi Jong Soo Cho Jeong-Tak Moon Kyu Hwan Oh 《Gold bulletin》2011,44(4):231-237
Inhomogeneous microtexture evolution during the cold drawing process usually results in lean, sway, or sweep failure. The
<111> longitudinal fiber texture has higher stiffness than the <100> texture and its proportion and distribution in the cross-section
are critical for the bonding stability of fine gold wire. We investigated the inhomogeneous microtexture evolution of gold
wire that was cold drawn through an asymmetric diamond die. In this study, the distributions of the <111> and <100> textures
in a 20 μm diameter fine gold wire are the variables and their effects on the bonding stability of the wire were estimated
by electron backscattered diffraction (EBSD) and finite element method (FEM) simulations. The use of a focused ion beam apparatus
enabled a high quality of band contrast of the EBSD to be achieved in the exact half cross-sectional area of the fine gold
wire. The detailed three-dimensional FEM results show that the asymmetric distribution of the textures plays a crucial role
in increasing the spatial displacement of the gold bonding wire. 相似文献
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