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The low temperature behaviors of Li/TEGDME/S cell was examined using discharge curves, SEM and impedance spectra. The first discharge capacity of Li/S cell with tetra(ethylene glycol) dimethyl ether (TEGDME) electrolyte was 1303 mAh g −1 -sulfur at 20 °C, but 357 mAh g −1 -sulfur at low temperature of −10 °C. The low temperature discharge characteristic is improved by adding 1,3-dioxolane (DOXL) and methylacetate (MA) to TEGDME electrolyte. The optimum composition of mixed electrolyte is MA–DOXL–TEGDME (5:47.5:47:5, v/v). The Li/S cell using the optimum electrolyte has the first discharge capacity of 994 and 1342 mAh g −1 -S at −10 and 20 °C, respectively.

We investigated self-discharge characteristics of Li/S batteries using tetra ethylene glycol dimethylether (TEGDME) electrolyte. The open circuit voltages (OCV) and discharge curves were measured as a function of storage time. The self-discharge of the Li/S battery depended on current collectors. Li/TEGDME/S batteries with stainless steel (SUS) current collector showed the highest self-discharge rate of 59% per month. The self-discharge rate of Li/TEGDME/S battery using Al current collector is 34% during initial 80 days, but only 36% after 360 days storage. The discharge capacity decreases only 2% from 80 to 360 days. The self-discharge of Li/S battery using Al current collector is severe during initial 80 days, but is not an important factor after 80 days. Average self-discharge rate of Li/TEGDME/S battery using Al current collector is 3% per month for 1 year.

The microstructure of Ni sulfides prepared by thermal sulfidation of pure Ni and their dependence of fabrication parameters were investigated by means of scanning electron microscopy and X-ray diffractions. Sulfidation was made by isothermally annealing Ni with the sulfur in vacuum sealed glass ampoules at 673 K for 120 – 600s under the sulfur pressure of 100 and 220 kPa. The sulfide layers formed in the early stage were found to consist of spherical particles smaller than 0.5um, which were grown and agglomerated with increasing annealing temperature. Thickness of sulfides developed on Ni substrate was found to increase with increasing annealing time and sulfur pressure. It was also found that compositions of dominant Ni sulfides changed with varying annealing time. At the initial stage, only Ni3S2 sulfide was formed on pure Ni, which was tightly bonded to Ni substrate. On increasing annealing time, NiS sulfide was formed. On further increasing annealing time, NiS1.97 sulfide was formed, which always coexisted with NiS sulfide. A mechanism for sulfidation of Ni is proposed as follows: 3Ni + 2S Ni3S2, Ni3S2 +S NiS, NiS + S NiS1.97

Iron(Fe)-molybdenum(Mo) alloyed nanopaticles and nanowires were produced by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl(Fe(CO)5) and molybdenum hexacarbonyl(Mo(CO)6). The influence of CVC parameter on the formation of nanoparticle, nanowire and size control was studied. The size of Fe-Mo alloyed nanoparticles can be controlled by quantity of gas flow. Also, Fe-Mo alloyed nanowires were produced by control of the work chamber pressure. Obtained nanoparticles and nanowires were investigated by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction.

FeSx nanoparticles were synthesized by the chemical vapor condensation (CVC) process using the pyrolysis of iron pentacarbonyl (Fe(CO)5) and sulfur (S). The influence of CVC parameter on the formation of nanoparticle and size distribution was studied. The synthesized nanoparticles consisting of FeS, FeS2 and Fe2O3 were nearly spherical shape and 5~40 nm in mean diameter. Obtained particles were studied by applying the field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) methods. Electrochemical properties of the electrode fabricated with synthesized nanoparticles were evaluated.

The electrochemical properties of Si/Ni/Cu film electrodes fabricated with different Ni film thicknesses were evaluated by investigating their structural properties. As the Ni film thickness increased from 0.5 to 3.5 μm, the growth behavior of the Ni film was changed from a fine grain structure to a column structure grown preferentially. The morphology of Ni clusters was also changed from round to trigonal due to the increase of the interfacial energy between the Ni and the Cu increased greatly with increasing Ni film thickness. The formation of trigonal clusters in the 3.5-μm film reduced the stress in the film and enhanced the adhesion between the Si film and the Ni film. The structurally stabilized Si electrode with a 3.5-μm thick Ni film improved the electrochemical properties of the Li/Si thin film cell.

We investigated the effects of multi-walled carbon nanotubes (MWNT) and graphitic nanofibers (GNF) on the performance of sulfur electrode for the lithium/sulfur battery. MWNT and GNF were manufactured by a thermal chemical vapor deposition (CVD) method, and then they were added as an additive in the sulfur electrode. The added sulfur electrodes were composed of 60wt% elemental sulfur (Aldrich), 20wt% acetylene black, 5wt% MWNT or GNF, and 15wt% poly ethylene oxide (PEO) dissolved in acetonitrile. No-added sulfur electrodes were prepared by mixing 60wt% elemental sulfur, 25wt% acetylene black, and 15wt% PEO. The addition of MWNT and GNF was found to give good electrochemical effects in sulfur electrode.

Ti and Ni sulfides were formed on the surface of Ti-Ni alloys by isothermal annealing at various sulfur pressures, and then microstructures of the surface sulfide layers were investigated by means of scanning electron microscopy and X-ray diffractions. Morphology of sulfurized surface changed from granular shape to porous shape at the sulfur pressure of 80 kPa, which is related to the change in sulfide from NiS1.97 to NiS. Two-layered sulfide was observed in which the inner layer was mainly Ti8.2S11 , and the outer layer was a mixture of NiS1.97 and NiS. The discharge curve of the Ti and Ni sulfides cathode formed on the Ti-Ni current collector at the first cycle showed a plateau voltage of 1.6 V, and the discharge capacity was found to be about 530 mAh/g-NiS1.97.

The lithium/sulfur cell is very attractive because of its high theoretical specific capacity and low production cost. The sulfur electrode is prepared from sulfur, with carbon as an electronic conductor and PEO as an ionic conductor. We changed the carbon content of a 50 wt.% sulfur electrode from 10 wt.% to 40 wt.%. The lithium/PEO/sulfur cell showed two plateau potential regions (2.4 V, 2.1 V) and high discharge capacity, i.e., 1484 mAh/g (88% utilization) for optimum composition. The discharge capacity decreased drastically by charge-discharge cycling. The degradation rate as well as the first discharge capacity depended on the composition of the sulfur electrode. The optimum composition of the 50 wt.% sulfur electrode was 30 wt.% carbon and 20% PEO.

Electrochemical and interfacial properties of (PEO)10LiCF3SO3−Al2O3 composite polymer electrolytes (CPEs) prepared by either ball milling or stirring are reported. Ball milling was introduced into a slurry preparative technique utilizing PEO, lithium salt and Al2O3 powder ranging from 5 to 15 wt.%. The ionic conductivity was increased by ball milling over a range of temperatures. In particular, a significant increase at low temperature below the melting point of crystalline PEO was observed. Interfacial stability between lithium electrode and CPE was significantly improved by the addition of alumina as well as by ball milling. The electrochemical stability window produced by (PEO)10LiCF3SO3−Al2O3 ball milling was higher than that of stirring, which was about 4.4 V. Charge/discharge performance of Li/CPE/S cells with (PEO)10LiCF3SO3−Al2O3-12 hr ball milling was superior to that of a pristine polymer electrolyte due to the low interface resistance and high ionic conductivity.

Grain size control by thermo-mechanical treatment is investigated in aluminum-lithium alloys. Rolling and subsequent recrystallizing treatment have been widely employed to obtain a fine grained structure. Humphreys has reviewed the recrystallization process in particle containing alloys and proposed a new deformation zone model. He thought that subgrain size or dislocation density increased abruptly beyond the deformation and boundary. He considered that a recrystallization nucleus formed and grew fast within the deformation zone. For nucleation of new grains, the maximum misorientation within the deformation zone should be sufficient to form a high angle boundary in the matrix, and for continuous growth of the nucleus, the deformation zone should be larger than critical size R{sub cr}. In this work, the recrystallization behaviors of Mn-free and Mn-bearing Al-Li alloys at various recrystallization temperatures were investigated to confirm the deformation zone model proposed by Humphreys.

FAD-dependent glucose dehydrogenase (FAD-GDH) of Burkholderia cepacia was successfully expressed in Escherichia coli and subsequently purified in order to use it as an anode catalyst for enzyme fuel cells. The purified enzyme has a low Km value (high affinity) towards glucose, which is 463.8 μM, up to 2-fold exponential range lower compared to glucose oxidase. The heterogeneous electron transfer coefficient (Ks) of FAD-GDH-menadione on a glassy carbon electrode was 10.73 s(-1), which is 3-fold higher than that of GOX-menadione, 3.68 s(-1). FAD-GDH was able to maintain its native glucose affinity during immobilization in the carbon nanotube and operation of enzyme fuel cells. FAD-GDH-menadione showed 3-fold higher power density, 799.4 ± 51.44 μW cm(-2), than the GOX-menadione system, 308.03 ± 17.93 μW cm(-2), under low glucose concentration, 5 mM, which is the concentration in normal physiological fluid.

Carbon nanotubes (CNTs) have attracted considerable interest because of their unique physical, electrical properties and many potential applications. Carbon nanotubes are considered to be the most promising candidate in electrode materials for secondary battery, solar cell and supercapacitor. Non-conductive substrates, such as silicon wafers have usually been used to synthesize CNTs. However, in applications such as electrodes, it is desirable to have CNTs grown on conductive buffer layer and conductive substrates. We researched the fabrication of carbon nanotubes on Ni/TiO2/Ti substrate by Thermal chemical vapor deposition (TCVD). Experimental parameter is synthesis temperature, time and buffer layer thickness. The samples were characterized by means of field emission scanning electron microscopy (FE-SEM), Raman spectroscopy analysis, transmission electron microscope (TEM) and electrochemical test. The synthesized CNTs have the diameter of about 100~200 nm and the length of about 5~10 μm. Li/CNTs cell with CNTs on Ti substrate exhibited good charge/discharge behavior and slow capacity fading.

Nanostructured nickel sulfide as a cathode material for lithium ion batteries was fabricated. The large surface area of reaction between electrodes and electrolyte offers high energy density and capacity. Also, metal sulfides have high theoretical capacity. Nickel nanowires were fabricated by electrochemical deposition (ECD) using an anodic aluminum oxide (AAO) template with the diameter of 200 nm. Fabricated nickel nanowires were carried out with sulfuration treatment. The morphology and microstructure of the nanowires were characterized with FE-SEM, XRD, TEM and XPS. Nickel sulfide nanowires were applied for lithium ion batteries and charge/discharge tests were carried out with galvanostatic method.

We have successfully synthesized beta-Ga2O3 nanomaterials with various morphologies, such as wire, rod, belt and sheet-like, through simple thermal evaporation of metal gallium powder in the presence of nickel oxide catalyst. beta-Ga2O3 nanomaterials with different morphology were observed as a function of synthesis time and temperature. In this report, generation sites of the beta-Ga2O3 nanomaterials have been delicately surveyed by FESEM. The growth mechanisms of nanomaterials are distinguished by the view of its generation site. The growth of nanowire follows both VLS and VS mechanism and other kinds of materials such as nanorod, nanobelt and nanosheet follows VS mechanism.

A highly ordered mesoporous carbon, AlCMK, with an assembly of carbon rods and a bimodal pore system is used for sulfur encapsulation, and the AlCMK/S composite is observed to be able to accommodate volume expansion during a discharge process and recover its original structure when recharged. It is proved that the assembly structure of AlCMK makes it “breath” during the redox reaction of lithium and sulfur. Such a novel ability greatly benefits the maintenance of electrode construction during a repeated discharge–charge process. Moreover, a long heating time (e.g. 20 h) at 300 °C in a two-step melt diffusion method is found to contribute to the uniform dispersion of sulfur in the AlCMK carbon matrix. Using this featured composite, a Li–S cell retains 627 mA h g−1 after 450 cycles at 0.1 C-rate with a coulombic efficiency close to 100% and also shows good rate capability up to 5 C-rate, demonstrating a significant improvement of reversible capacity and cycle stability of Li–S cells.

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Various kinds of β-Ga2O3 nanomaterials such as nanowires, nanorods, nanobelts, nanosheets and nanocolumns have been successfully synthesized by simple evaporation of gallium powder with no assisted catalyst in a flow of argon gas. The as-synthesized materials were pure, structurally uniform, single crystalline with monoclinic β-Ga2O3 structure (space group: C2 m−1) and free from defects. The synthesized nanomaterials were deposited with a growth order of nanocolumn/nanorod, nanowire/nanobelt and nanosheet with synthesis time. The nucleation site was looked over in detail. We present evidence that the surface, edge and tip of previously grown β-Ga2O3 nanomaterials again provide a nucleation site of new β-Ga2O3 nanomaterials. Because no metal catalysts were introduced into our growth, a vapor–liquid–solid (VLS) growth is not the likely process in this work, indicating that the observed nanomaterials were grown via a vapor–solid (VS) mechanism.

In order to investigate the electrochemical properties of Si electrodes deposited on a roughened current collector (substrate), the electrochemical etching method was applied to a Cu current collector. The surface roughness of a Cu current collector could be controlled with an electrochemical etching time and the roughest surface was obtained at 20 min etched Cu foil. After the etching, a thin Cu2O film was formed on the surface due to high reactivity with air. Amorphous Si films were deposited on flat and rough substrates and their morphologies were considerably affected by those of substrates. A Si electrode with a rough current collector exhibited remarkably improved cycle performance and maintained a discharge capacity over 1200 mA h g−1 even after the 50th cycle. The formation of large cracked Si tiles was caused by the improved adhesion between Si film and Cu substrate.

Well-ordered TiO2 nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH4F and H2O. The influence of anodization temperature and time on the morphology and formation of TiO2 nanotube arrays was examined. The TiO2 nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO2 nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO2 nanotube arrays in the manufacturing process of a photoelectrode.

Li–Fe–S ternary metal sulfide (lithium iron sulfide) powder was synthesized by the molten salt method. The physical and electrochemical properties of synthesized lithium iron sulfide were also investigated. From the results of XRD analysis, the chemical composition of synthesized lithium iron sulfide powder was Li1.7Fe1.17S2 with a hexagonal crystal structure. The Li/Li1.7Fe1.17S2 cell showed a first charge capacity of 153 mAh g−1-Li1.7Fe1.17S2, corresponding to 48% of theoretical capacity. To understand the charge/discharge reaction behaviors of the Li/Li1.7Fe1.17S2 cell, Li/FeS2,Li/Fe and Li/AB cells were tested. From these results, the charge/discharge mechanism of the Li/Li1.7Fe1.17S2 cell was suggested.

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Surface Ni sulfides layers were formed on the surface of a Ti-50.0Ni alloy by reacting sulfur and Ni film deposited on the alloy, and then microstructures, transformation behavior, shape memory characteristics, superelasticity and electrochemical properties of a Ti-50.0Ni(at%) alloy with the sulfides were investigated. When Ni film deposited on a Ti-50.0Ni alloy was annealed under the sulfur pressure of 100 kPa at 623 K, sulfides layers consisted of NiS and NiS 1.97 were formed. When annealing was made at 648 K annealing with annealing time less than 0.9 ks, sulfides layers consisted of NiS and NiS 1.97 were formed also, while only NiS 1.97 was formed when it was made for 1.8 ks. When annealing was made at 673 K annealing with annealing time longer than 0.9 ks, only NiS 1.97 was formed. A Ti- 50.0Ni(at%) alloy with surface NiS 1.97 layer showed the two-stage B2-R-B19' transformation behavior, the perfect shape memory effect and a partial superelasticity with a superelastic recovery ratio of 78 %. NiS 1.97 cathode showed a clear discharge behavior with multi voltage plateaus. Discharge capacity of NiS 1.97 cathode decreased abruptly with increasing number of cycles up to 3, above which it decreased gradually.

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.