In this study, the multicomponent electrode approach was used in an attempt to simultaneously improve the cell's specific energy values by shifting the cathode's voltage up to the 5V-region, combined with the increased specific capacity via addition of the second electrode component. The electrode materials were prepared by variety of synthetic methods (e.g. solid state, sol-gel, mechanical mixing etc.) and tested for lithium-ion intercalation properties. Structural properties and morphology of synthesized materials were characterized by X-ray diffraction (XRD) methods. The prospective 5V cathode materials were investigated as cathodes in the cells with lithium-metal counter electrode.

Carbon-based micro-supercapacitors dedicated to energy storage in self-powered modules were fabricated with inkjet printing technology on silicon substrate. The ink containing activated carbon with particles size ranging from 1 μm to 10 μm, mixed with PTFE and glycol was stabilised with a surfactant, Triton X100. After functionalising the electrodes surroundings with octadecyltrichlorosilane (OTS), the ink was deposited by inkjet on the electrodes with the substrate heated at 140°C in order to assure a good homogeneity. The resulting structures have a resolution of 10 μm. Micro-supercapacitors with the carbon electrodes were tested in acetonitrile and Et4NBF4 dried salts: the capacitance density obtained was 50 μF.cm−2. The newly developed technology will allow the integration of the storage device as close as possible as the MEMS-based energy harvesting device, minimising power losses through connections.

Microscopic mechanism of Hydrogen-Induced Amorphization (HIA) in AB2 C15 Laves phase compound is studied. Experimentally, compounds in which A atoms are contracted and B atoms are expanded in Laves phase show HIA. It suggests that the relative atomic size is the controlling factor. We investigate the role of the size effect by molecular Dynamics (MD) methods using Lennard-Jones pair-wise potentials. Our simulations show that in such a compound, the bulk modulus is remarkably reduced by hydrogenation compared to the isotropic tensile load, so that elastic instability is facilitated. This situation is caused by the negative increase of the pressure-fluctuation contribution in the elastic constant. The relaxation of B-atom positions by hydrogenation gives the fluctuation contribution. The fluctuation effect is essential in the elastic instability, although the energy change is small.

Activated carbons have been mechanochemically modified by bromine incorporation through high-energy milling route. Varying the milling duration and bromine content, carbon-bromine nanocomposites of different compositions were fabricated. The highly reactive and electronegative bromine reacts with host carbon, which can modify its characteristic properties. We have examined the effect of bromination on the structure, chemistry, morphology and electrochemical properties of a mesoporous activated carbon. Bromination leads to possible charge transfer reaction, structural disordering with polybromide formation. Consequently, the non-faradaic capacitance improves and a faradaic pseudocapacitive reaction occurs at 3.1 V and a more traditional bromine reduction at 3.5V. The formation of carbon-bromine nanocomposites was found to deliver improved gravimetric and volumetric capacity. The effect of bromination on physical and electrochemical properties of activated carbons have been presented and contrasted to that of iodine incorporation.

The remarkable ability of magnesium to store significant quantities of hydrogen has fostered intense research efforts in the last years in view of its future applications where light and safe hydrogen-storage media are needed. Magnesium material, characterized by light weight and low cost of production, can reversibly store about 7.7 wt% hydrogen. However, further research is needed since Mg has a high operation temperature and slow absorption kinetics that prevent the use in practical applications. For these reasons a detailed study of the interface between Mg and MgH2 is needed. Further insights are gained by characterizing the Mg-MgH2 system from both the experimental and the numerical point of view.

The study of the MgH2-Mg phase transformation in powder samples has been performed to gain detailed metallographic information. A method for studying this phase transformation by cross sectional samples scanning electron microscopy observation of partially transformed material has been developed. This method exploits the peculiar features of this system where the MgH2 phase is insulating and the Mg is a metallic conducting phase. This difference can induce a contrast between the two phases owing to the different secondary emission yield. Further insights are gained by characterizing Mg-MgH2 interfaces by means of accurate first-principle molecular dynamics simulations based on the density-functional theory. Extensive electronic structure calculations are used to characterize the equilibrium properties and the behavior of the surfaces in terms of total energy considerations and atomic diffusion.

A novel Ce4+/Ce3+- V2+/V3+ redox flow cell has been investigated. It was composed of the Ce4+/Ce3+ couple, which replaced the V5+/V4+ couple of the all6vanadium redox flow cell, and the V2+/V3+ couple. The normal potential and the kinetic parameters for anodic oxidation of Ce3+ and cathodic reduction of Ce4+ were measured. The results showed that the surface of platinum electrode was fully covered with type I oxide that inhibited the reduction of Ce4+. The reversibility of the Ce4+/Ce3+ couple improved with the increase of H2SO4 concentration, but both higher energy efficiency and coulombic efficiency were observed in 0.5 mol/dm3 H2SO4 solution. Different electrochemically active substances were found to exist at various state of charge (SOC) and the reversibility of the Ce4+/Ce3+ couple at the carbon electrode was found to be superior to platinum electrode. Periodic charge6discharge measurements were conducted under constant current and constant load with the proposed Ce6V redox flow cell. The results indicated that the coulombic efficiency remained around 90% and the discharge voltage stabilized between 1.5 and 1.2 V. But as the cycle numbers increased, the discharge capacity declined a bit and a better result might be expected by improving the separator materials and increase the concentration of electro6active materials. By comparison with the existing Fe6Cr, Fe6Ti and all6vanadium redox flow cell, the Ce6V system has a higher open6circuit voltage (OCV). And results from this preliminary study suggest that the novel Ce6V redox flow cell is a promising energy storage system and is worthy of further studies.

We synthesized a methanol electrocatalyst with high activity and low noble metal content. The electrocatalyst consists of carbon&supported PtRu nanoparticles, which have 1-2 Pt monoatomic layers on Ru nanocores. In spite of the pure Pt surface, the catalyst showed high catalytic activity when used in the anode of a direct methanol fuel cell. Clearly the underlying Ru atoms modified the property of the surface Pt atoms, bringing about the high catalytic activity.

GaN nanodots and nanorods were successfully grown on Si (111) substrates by molecular beam epitaxy. Photocurrent densities of GaN nanodots were quite small compared with thick GaN layer grown by metal-organic vapor phase epitaxy. The current density, however, increases with GaN nanodot density. The highest photocurrent density of the GaN nanodots was higher than that of the layer structure with similar thickness (up to 10 nm) to the nanodot height. GaN nanorods have much higher photocurrent density than that of GaN nanodots. Enough nanostructure size for light absorption is important to achieve good photoelectrochemical performance.

TiO2 is an attractive anode material for Li-ion batteries due to its high capacity, high mechanical stability during Li intercalation/deintercalation process, limited side reactions with the electrolyte, low cost, and environmental friendliness. In this study, titanium hydroxide gel films were prepared in acidic aqueous solutions of TiOSO4, H2O2 and KNO3 by potentiostatic cathodic electrosynthesis on various copper substrates, including planar Cu foil, mechanically polished planar Cu foil, and Cu nanorod arrays grown on Cu foil. Crystalline TiO2 films were obtained by heat treating the electrodeposited titanium hydroxide gel films at 500 oC in argon atmosphere. The morphology and microstructure of the TiO2 films were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). SEM results showed that after deposition, each Cu nanorod has been covered by a layer of TiO2 gel, forming a core-shell structure. The effects of Cu nanorod arrays on the morphology and the electrochemical property of the TiO2 deposits were discussed.

Very high surface area nanostructured metal electrodes are of interest as efficient current collectors. For thin film devices, the nanostructured metal can be grown in place using electrodeposition or electroless deposition. For larger devices metal electrodes structured at more than one length scale are desirable. Self-assembling surfactant templates are a versatile method of generating a range of nanostructures. As we report here, electrodeposition of nickel, cobalt and copper from liquid crystalline solutions of Triton X-100 produces a number of nanostructures, with significant surface area increases. Electrodeposition into templates with microstructure has proven more demanding. Oil-in-water Microemulsions of Tween surfactants and soy oil, produce micrometer scale structures, however measured nickel surface area does not scale with sample thickness. The method is also not robust, and was found to give microstructures only for nickel and cobalt. Experiments show that under our conditions a combination of nickel metal, nickel acetate and nickel/detergent microstructures are formed.

In this work we present the study of fabrication, Ge incorporation, structure and electronic properties of nano-structured GeySi1-y:H films with y>0.5 prepared by low frequency (LF) PECVD. GeySi1-y:H films were deposited by LF PECVD at a frequency f= 110 kHz from SiH4+GeH4+H2 gas mixture. SiH4 and GeH4 flows were varied to fabricate the films in wide range of 0<y<l. Hydrogen dilution was varied in the range of RH =20 to 80. Structure of the films was studied by AFM and SEM with consequent image processing to extract statistical parameters such as grain distribution and mean values. Composition of the films was characterized by SIMS and EDX. Electronic properties were characterized by temperature dependence of conductivity, spectral dependence of optical absorption. Sub-gap absorption was characterized by Urbach energy, EU; and defect absorption, αD. We observed grain like nano-structure with Gauss distribution of grain diameters by both AFM and SEM measurements. The most interesting films had mean grain diameter<D> = 24.0±0.7 nm, dispersion D=11.0±0.2 nm and fill factor FF=0.313, Ge content y=0.96-0.97(by SIMS and EDS). These films showed also the lowest values of Urbach energy EU = 0.030 eV and low defect absorption αD = 5×102 cm −1 (at photon energy hv = 1.04 eV) indicating on low density of localized states in mobility gap. Doped films have been also fabricated and studied. Finally we shall discuss application of the above films in photovoltaic devices.

In this study, we explored the synthesis of LiMnPO4 through hydrothermal methods using urea as the hydroxide ion source. The hydrothermally prepared LiMnPO4 was examined through x, ray diffraction, microscopy, surface area and electrochemical measurements. Small crystallites were formed and significant agglomeration of particles was observed. The effect of additives to control nucleation and growth of the LiMnPO4 is reported. None of the attempted additives led to the desired morphology. At a C/5 discharge rate, a capacity of about 53 mAh/g was observed for a carbon coated sample of hydrothermally prepared LiMnPO4.

A novel electroactive nanostructured silver molybdenum oxyfluoride (SMOF) perovskite was successfully synthesized via mechanochemistry through the use of AgFx and MoO3. The structure of the SMOF perovskite has been examined utilizing X-ray powder diffraction (XRD) combined with X-ray absorption spectroscopy (XAS) and elemental analysis. The SMOF perovskite exhibited a very good electrochemical activity. A detailed in-situ electrochemical study by XRD and XAS was carried out. Finally, preliminary work on fabrication of a metallic Ag2F phase and optimization of the rate capability of SMOF perovskite is presented.

Lithium bis(oxalato)borate (LiBOB) has gained widespread interest as an electrolyte salt for lithium ion batteries because of its high conductivity, low cost, thermal stability, and adequate solubility in many organic solvents [1]. Cyclic voltammetric data taken on platinum [2] and carbon [3] indicate electrochemical stability over a wide potential range.

We show that bis(oxalato)borate (BOB) can be reduced at about 1.75 volts anodic to lithium, by discharging electrolytes at low current density (0.1 mA/cm2) on high surface area carbon electrodes containing a mixture of acetylene and Ketjen carbon blacks. The evidence includes discharge profiles and 11B NMR data. The behavior of discharge plateaus indicates that BOB is reduced to a soluble species with electrolytic properties, and the appearance of a broad 11B NMR peak in the electrolyte indicates that the reduced species undergoes extensive exchange.

We report here a series of high-conductivity liquid- and gel-electrolytes based on a mixture of ethyleneoxy phosphazenes and propylene carbonate, which have potential applications in lithium battery assembly. Phosphazene compounds are known to be good materials for solid polymer lithium electrolytes and, following that idea, we have developed low-volatility liquid phosphazene electrolytes that maintain 10−4 S/cm conductivity. A high conductivity of 10−3 S/cm can be achieved when polymeric phosphazenes are used as solidifying agents for conventional battery electrolytes. We also report here the fire retardant properties of the materials, which may lead to future use of these materials as fire retardant additives.

The electrochemical cycling performance of high purity single wall carbon nanotube (SWCNT) paper electrodes has been measured for a series of electrolyte solvent compositions. The effects of varying the galvanostatic charge rate and cycling temperature on lithium ion capacity have been evaluated between 25-100 °C. The measured reversible lithium ion capacities for SWCNT anodes range from 600-1000 mAh/g for a 1M LiPF6 electrolyte, depending on solvent composition and cycling temperature. The solid-electrolyte-interface (SEI) formation and first cycle charge loss are also shown to vary dramatically with carbonate solvent selection and illustrate the importance of solvent alkyl chain length and polarity on SWCNT capacity. SWCNT anodes have also been incorporated into full battery designs using LiCoO2 cathode composites. An electrochemical pre-lithiation sequence, prior to battery assembly, has been developed to mitigate the first cycle charge loss of SWCNT anodes. The pre-lithiated SWCNT anodes show reversible cycling at varying charge rates and depths of discharge with the cathode system. The summary of data shows that the structural integrity of individual SWCNTs is preserved after cycling, and that free-standing SWCNT paper electrodes represent an attractive material for lithium ion batteries.