Fe₃O₄/Fe/graphene nanocomposite powder is synthesized by electrical wire explosion of Fe wire and dispersed graphene in deionized water at room temperature. The structural and electrochemical characteristics of the powder are characterized by the field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, field-emission transmission electron microscopy, cyclic voltammetry, and galvanometric discharge-charge method. For comparison, Fe₃O₄/Fe nanocomposites are fabricated under the same conditions. The Fe₃O₄/Fe nanocomposite particles, around 15-30 nm in size, are highly encapsulated in a graphene matrix. The Fe₃O₄/Fe/graphene nanocomposite powder exhibits a high initial charge specific capacity of 878 mA/g and a high capacity retention of 91% (798 mA/g) after 50 cycles. The good electrochemical performance of the Fe₃O₄/Fe/graphene nanocomposite powder is clearly established by comparison of the results with those obtained for Fe₃O₄/Fe nanocomposite powder and is attributed to alleviation of volume change, good distribution of electrode active materials, and improved electrical conductivity upon the addition of graphene.

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• Preparation of magnetic metal and graphene hybrids with tunable morphological, structural and magnetic properties
  Kyunbae Lee, Joonsik Lee, Byung Mun Jung, Byeongjin Park, Taehoon Kim, Sang Bok Lee
  Applied Surface Science.2019; 478: 733.     CrossRef

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

Tin is one of the most promising anode materials for next-generation lithium-ion batteries with a high energy density. However, the commercialization of tin-based anodes is still hindered due to the large volume change (over 260%) upon lithiation/delithiation cycling. To solve the problem, many efforts have been focused on enhancing structural stability of tin particles in electrodes. In this work, we synthesize tin nano-powders with an amorphous carbon layer on the surface and surroundings of the powder by electrical wire explosion in alcohol-based liquid media at room temperature. The morphology and microstructures of the powders are characterized by scanning electron microscopy, Xray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical properties of the powder for use as an anode material for lithium-ion battery are evaluated by cyclic voltammetry and a galvanometric dischargecharge method. It is shown that the carbon-coated tin nano-powders prepared in hexanol media exhibit a high initial charge specific capacity of 902 mAh/g and a high capacity retention of 89% after 50 cycles.

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• Optimization of carbon coating thickness to prevent crack generation in Sn nanoparticles during charge/discharge process and their electrochemical properties
  Ji-Seub Choi, Yeon-Ju Lee, Hoi-Jin Lee, Gyu-Bong Cho, Jai-Won Byeon, Hyo-Jun Ahn, Ki-Won Kim, Jou-Hyeon Ahn, Kwon-Koo Cho
  Journal of Alloys and Compounds.2020; 843: 155892.     CrossRef
• Fabrication of multilayer graphene-encapsulated Sn/SnO2 nanocomposite as an anode material for lithium-ion batteries and its electrochemical properties
  Ju-Seok Song, Gyu-Bong Cho, Ki-Won Kim, Hyo-Jun Ahn, Hye-Sung Kim, Jou-Hyeon Ahn, Kwon-Koo Cho
  Applied Surface Science.2019; 481: 736.     CrossRef