Duk Hee Lee

Highly Reversible Li Storage in Hybrid NiO/Ni/Graphene Nanocomposites Prepared by an Electrical Wire Explosion Process

NiO/Ni/graphene nanocomposites were prepared using a simple and environmentally friendly method comprising an electrical wire pulse technique in oleic acid containing graphenes and subsequent annealing to form anodes for Li ion batteries. The control product of NiO/Ni nanocomposite was prepared under the same conditions and characterized by structural and electrochemical analysis. The obtained NiO/Ni/graphene nanocomposite particles had sizes of 5-12 nm and a high surface area of 137 m(2) g(-1). In comparison to NiO/Ni, NiO/Ni/graphene exhibited improved cycling performance and good rate capability. Reversible capacity was maintained at over 600 mA h g(-1) at 0.2 C and was attributed to the alleviation in volume change and improved electrical conductivity of NiO/Ni/graphene nanocomposites.

Oleic-acid-assisted carbon coating on Sn nanoparticles for Li ion battery electrodes with long-term cycling stability

We report the one-pot synthesis of high-performance Sn@C nanocomposite anode materials obtained by uniform carbon coating onto Sn nanoparticles induced by electrical Sn-wire explosion in oleic acid liquid media at room temperature. This Sn@C nanocomposite exhibits highly reversible Li-storage performance with a specific capacity of ∼730 mA h g−1, even after 200 cycles.

Synthesis of Cu3(MoO4)2(OH)2 nanostructures by simple aqueous precipitation: understanding the fundamental chemistry and growth mechanism

Lindgrenite (Cu3(MoO4)2(OH)2) nanoflowers were synthesized through the simplest possible route by an aqueous chemical precipitation technique at room temperature without using any surfactants, template, expensive chemicals, complex instrumentation or tedious multistage synthesis process. Their morphology, structure, thermal properties, surface area, synthesis chemistry, and structural and growth mechanisms involved in the synthesis process were analyzed. Using XRD, FE-SEM, HR-TEM and FT-IR spectroscopy, their structure and morphology were analyzed. The thermal stability, surface area and porosity of the Cu3(MoO4)2(OH)2 nanoflowers were analyzed by TGA and BET. XRD analysis showed that the Cu3(MoO4)2(OH)2 nanoflowers have a pure monoclinic structure. The morphological analysis showed that the Cu3(MoO4)2(OH)2 nanoflowers are ∼10 μm in size, which are formed from self-assembly of thin nanosheets with a thickness of ∼20 nm. TGA indicated that the Cu3(MoO4)2(OH)2 nanoflowers are stable materials up to 328 °C and the isotherm from BET analysis indicated that the Cu3(MoO4)2(OH)2 nanoflowers are non-porous materials. The BET surface area of the synthesized Cu3(MoO4)2(OH)2 nanoflowers was found to be 21.357 m2 g−1. Moreover, the effects of the pH value and reaction time on the morphology of the Cu3(MoO4)2(OH)2 nanoflowers were studied and their optimization was performed. The results of the optimization study indicated that the reaction time and pH are two important parameters influencing the nucleation, growth, morphology, and synthesis mechanism. These flower-shaped Cu3(MoO4)2(OH)2 nanostructures are promising precursors for preparing molybdenum oxide materials which have various applications and can be synthesized in a very simple one-pot reaction system using commonly available chemicals without using a complex route.