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Helices made of varying Cu-Si atomic ratios (10-90, 20-80, 30-70%) are fabricated by an ion-assisted glancing angle co-deposition technique. Cu is added into the electrode because of its ductility and electron conductivity. Thus, Cu holds the electrode together, minimizing overall capacity loss and enabling faster electron transfer. Plus, Cu is inactive versus Li+; therefore, Cu/Si variation in the films is expected to affect the physical and electrochemical performances of the electrodes. The morhological analyses demonstrate that an increase in Cu/Si atomic ratio affects the width of the helices and the homogeneity in the thin film morphology. The galvanostatic tests show that Sample 1 (with 30%at.Cu) performs 3389 mAh g-1with 49% capacity retention where as Samples 2 (with 20%at.Cu) and 3 deliver 1885 and 1680 mAh g-1as initally discharge capacities and retain 77% and 53% of their first discharge capacities after 100thcycle.

This study explores the electrochemical performance of M/Sn/M (M:Ni and Cu) anodes in rechargeable lithium ion batteries. Sandwich electrode is proposed to improve the electrochemical performance of Sn anode. Herein the electrochemical performances of Cu/Sn/Cu and Ni/Sn/Ni films are compared to that of the pure Sn electrode. The galvanostatic test results prove that stress buffering action of M (M: Cu,Ni), differentiation in the surface reactivity of the electrode, improved the adhesion of the film. After 30 cycle, the capacities of the pure Sn, the Cu/Sn/Cu and the Ni/Sn/Ni films are 22mAh g-1, 140mAh g-1, 205 mAh g-1respectively. It is demonstrated that the sandwich model improves cycle performance of the electrode.

Films with nanorods made of various Cu-Si atomic ratios (10-90%, 20-80%, 30-70%) were fabricated by an ion-assisted oblique angle co-deposition technique. The effect of Cu/Si atomic ratios on the morphologies and the structures were studied by SEM and XRD. The use of those nanorods as anode materials in lithium ion batteries were evaluated by galvanostatic test results. The SEM analyses demonstrate that during the co-evaporation an increase in Cu/Si atomic ratio decreases the nanorod width and height but increases the nanorod tilting angle. The galvanostatic tests show that the Sample 1 (film having 70% at. Si) performs 900mAh/g as the first discharge capacity with a higher initial coulombic efficiency (80%) and it retains 40% of its first discharge capacity after 100 cycles due to higher amount of Cu, which improves its geometry and increases the electrical conductivity as well as the mechanical tolerance of the electrode. The samples 2 and 3 (films with 80% and 90%at. Si contents) deliver higher capacities with lower coulombic efficiencies (1720 and 2550 mAh/g with 68% and 54% coulombic efficiencies) compared to Sample 1 because of their amorphous structures and high Si contents. They only retain 30% and 20% of their first capacities after 100 cycles due to limited amount of Cu presence. The results show that an optimization is always required to perform high capacity with a good capacity retention for long cycle life.

In the present work, we deposited a bare and a (10 nm thick) Cu capped SiCu films (that contains 10 %at. Cu) by magnetron sputtering. The results showed that the top coating does not only exert remarkable favorable effects on the capacity, but also improves the capacity retention and coulombic efficiency. The galvanostatic test results showed that with C/12 rate, Cu capped SiCu film delivered 750 mAh/g after 40thcycles, and it retained stable up to 100 cycle with 98% coulombic efficiency, whilst the bare SiCu film performed a gradual decrease in capacity. We believe that during cycling, the top Cu film being ductile, form a network to prevent the electronic isolation of Si particles, or delamination. Cu atoms buffered the mechanical stress generated in the electrode following the volumetric changes. Furthermore, the surface reactivity of the SiCu electrode, hence its interaction with the electrolyte, was also changed leading to a longer cycle life electrode.

In this work, we produce layered Cu/Si film by deposition a thin Cu film on Si nanocolums by an oblique angle deposition method. Galvanostatic half-cell measurements show that, the Cu coated Si nanocolumn arrays performs 1700 mAh g-1in the first cycle, then after 10 cycles its performance is stabilized to 500 mAh g-1 with 99% coulombic efficiency for 90 cycles. This high performance is related to its particular morphology and physical properties. First, having homogenously distributed nano-sized porosities in the Cu coated film increases the mechanical tolerance of the electrode against the volumetric changes occurred during galvanostatic test. Second, the ductile behavior of the Cu film holds the electrode together to prevent the electronic isolation, pulverization or delamination of the coating. Third, Cu15Si4 intermetallics increase the mechanical resistances of the coating against the stress generated in the electrode. Last, the surface reactivity of the electrode, hence its interaction with the electrolyte, is also changedbecause of the Cu layer presence as interlayer, leading to higher coulombic efficiency once a stable SEI forms on the anode.

Synthesis of positive electrode materials for lithium ion batteries (LIB) plays a major role in battery performance. In this study, we first investigated the effect of chelating agents and calcination temperature on the production of LiNi0.8Co0.2O2cathode material. Then, by using mechanical mixing and sol-gel methods, tin oxide was introduced in the LiNi0.8Co0.2O2powder to enhance the electrochemical performance. The effects of chelating agents (citric acid, oxalic acid, adipic acid), calcination temperature (600-800 °C, @10 hours) and the tin oxide presence on the LiNi0.8Co0.2O2powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer, Emmmett and Teller (BET) analyses. Galvonastatic tests were performed in between 3-4.2 V at various C rates (0.2, 0.5, 1C).The powders produced by using adipic acid as chelating agent at 700 °C showed higher capacity and better electrochemical properties than those of powders synthesized by oxalic and citric acid. And sol-gel modified powders had higher initial capacity and better capacity retention than the mechanically modified and the bare powders. Sol-gel modified powders had more stable cycle characteristic and they had not shown immediate capacity fall even at higher C rates where they kept their capacity above 140 mAh/g even after 50 cycles.

This study proposes to produce well-aligned nanorod arrays containing NiSi thin film to improve the electrochemical performance of Si based anodes. In this respect, NiSi thin films made of nanorods are produced via glancing angle electron beam deposition (GLAD) technique. The structural and morphological properties are investigated using thin film X-ray diffraction (XRD) and scanning electron microscopy (SEM). The well aligned nanorod arrays containing NiSi thin film anode exhibits a long cycle life with a moderate capacity retention (around 1100mAhg-1 for 100 cycles). This remarkable electrochemical performance can be explained by the electrode composition, structure and morphology: During Li+ insertion into the alloyed thin film electrodes, Si acts as active center, which reacts with Li+to form amorphous LixSi alloys, while the nanosized Ni particles are believed to provide electrical conduction network inside the active material and buffer volume expansions with the help of the homogenously distributed nanosized interspaces (porosities among the nanorods) present in the thin film.

An oblique angle electron beam co-deposition technique was used to fabricate nanostructured Sn based thin films: Sn, Cu-Sn and Cu-Sn-C. The morphological and structural properties of the films were observed via scanning electron microscopy (SEM) and thin film X-ray diffraction methods (XRD). The cyclic voltammetry (CV) and the galvanostatic test results demonstrated that the addition of Cu with or without C affected the electrochemical performance of the thin film positively since Cu and C improved both the mechanical and the electrical properties of the nanostructured Sn thin film electrode. The high cycleability and the capacity retention were achieved when the nanostructured Cu-Sn-C thin film was used as an anode material since C increased the mechanical tolerance of the thin film to the volume expansion due to its grain refiner effect, and Cu not only improved the electrical conductivity and the adhesion of the film to substrate but also the mechanical tolerance of the film with its ductile property.