Electrochemical Behavior of Sn/Cu6Sn5/C Composite Prepared by Using Pulsed Wire Explosion in Liquid Medium for Lithium-Ion Batteries.

Tin-based materials, due to their high theoretical capacity of 994 mAh g-1 are potential candidates which can substitute the commercialized graphite anodes (372 mAh g-1). However, practical usage of pure tin in Li-ion cells has been hampered by the tremendous volume expansion of more than 260% during the lithium insertion/extraction process, resulting in particle pulverization and electrical disconnection from the current collector. In order to overcome this shortcoming, Sn/Cu6Sn5/C composites in this work were prepared by using pulsed wire explosion in a liquid medium and subsequently in situ polymerization. For comparison, Sn/C composite without tin-copper chemical compounds are also fabricated under a similar process. The Sn/Cu6Sn5/C and Sn/C composites were used as anodes for lithium-ion batteries. The Sn/Cu6Sn5/C composite anode showed good cyclability (scalability) and was maintained up to a capacity of 430 mAh g-1 after 100 cycles at 1 C-rate. The rate capability of the Sn/Cu6Sn5/C composite anode also showed higher performance (280 mAh g-1) than that (200 mAh g-1) of Sn/C composite at the 5 C-rate.

Synthesis and Electrochemical Properties of Amorphous Carbon Coated Sn Anode Material for Lithium Ion Batteries and Sodium Ion Batteries.

Sn is one of the promising anode material for lithium-ion and sodium-ion batteries because of Sn has many advantages such as a high theoretical capacity of 994 mAh/g, inexpensive, abundant and nontoxic. However, Sn-based anodes have a critical problem from pulverization of the particles due to large volume change (>300% in lithium-ion battery and 420% in the sodium-ion battery) during alloying/dealloying reaction. To overcome this problem, we fabricate Sn/C particle of core/shell structure. Sn powder was produced by pulsed wire explosion in liquid media, and amorphous carbon coating process was prepared by hydrothermal synthesis. The charge capacity of Sn electrode and amorphous carbon coated Sn electrode was 413 mAh/g and 452 mAh/g after 40 cycles in lithium half-cell test. The charge capacity of Sn electrode and amorphous carbon coated Sn electrode was 240 mAh/g and 487 mAh/g after 40 cycles in sodium half-cell test. Amorphous carbon coating contributed to the improvement of capacity in lithium and sodium battery systems. And the effect of amorphous carbon coating in sodium battery system was superior to that in lithium battery system.

Co-Ni alloy nanowires prepared by anodic aluminum oxide template via electrochemical deposition.

The alloy nanowires are more prospective magnetic and shape memory materials. Fabrication of binary or more alloy nanowires using electrochemical deposition process is generally challenging due to the different synthesis conditions of individual elements. In the present work, binary NiCo alloy nanowire arrays have been fabricated by electrochemical deposition using anodic aluminum oxide template medium technique. The optimum conditions (temperature, voltage and time) for synthesis of NiCo alloy nanowire array were achieved based on the ideal experimental conditions of single Ni and Co nanowire arrays. The synthesized NiCo alloy nanowire arrays were characterized by X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectrometer. The amorphous NiCo alloy nanowires were crystallized by annealing of 800 degrees C for 1 hour in argon atmosphere. The controlled composition of electrolyte provided to achieve a uniformly distributed chemical composition of Ni and Co (49.26:50.74) in nanowires.

Effect of precursor supply on structural and morphological characteristics of fe nanomaterials synthesized via chemical vapor condensation method.

Various physical, chemical and mechanical methods, such as inert gas condensation, chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and mechanical alloying, have been used to synthesize nanoparticles. Among them, chemical vapor condensation (CVC) has the benefit of its applicability to almost all materials because a wide range of precursors are available for large-scale production with a non-agglomerated state. In this work, Fe nanoparticles and nanowires were synthesized by chemical vapor condensation method using iron pentacarbonyl (Fe(CO)5) as the precursor. The effect of processing parameters on the microstructure, size and morphology of Fe nanoparticles and nanowires were studied. In particular, we investigated close correlation of size and morphology of Fe nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. The atomic quantity was calculated by Boyle's ideal gas law. The Fe nanoparticles and nanowires with various diameter and morphology have successfully been synthesized by the chemical vapor condensation method.

Physical and electrochemical properties of synthesized carbon nanotubes [CNTs] on a metal substrate by thermal chemical vapor deposition.

Multi-walled carbon nanotubes were synthesized on a Ni/Au/Ti substrate using a thermal chemical vapor deposition process. A Ni layer was used as a catalyst, and an Au layer was applied as a barrier in order to prevent diffusion between Ni and Ti within the substrate during the growth of carbon nanotubes. The results showed that vertically aligned multi-walled carbon nanotubes could be uniformly grown on the Ti substrate (i.e., metal substrate), thus indicating that the Au buffer layer effectively prevented interdiffusion of the catalyst and metal substrate. Synthesized carbon nanotubes on the Ti substrate have the diameter of about 80 to 120 nm and the length of about 5 to 10 µm. The Ti substrate, with carbon nanotubes, was prepared as an electrode for a lithium rechargeable battery, and its electrochemical properties were investigated. In a Li/CNT cell with carbon nanotubes on a 60-nm Au buffer layer, the first discharge capacity and discharge capacity after the 50th cycle were 210 and 80 µAh/cm2, respectively.