Thin film lithium batteries prepared by spray pyrolysis

We have prepared thin film cathode materials and thin film electrolytes at temperatures ranging from 400°C to 600°C by a spray pyrolysis technique. The sols used to prepare the films are made from simple inorganic salts and non toxic, inexpensive diols. The sols can be sprayed in an air atmosphere to prepare films of the desired crystalline materials. Paper presented at the 1st Euroconverence on Solid State Ionics, Zakynthos, Greece, 11–18 Sept. 1994     

Thin aluminum film improving the cycle performance of positive electrode of lithium ion battery

A novel method was investigated to improve the cycle performance of the spinel LiMn₂O₄. It is widely different from the traditional way of modifying LiMn₂O₄ particle with compounds or metals. In our study, instead of coating LiMn₂O₄ particle itself with compounds or metals, first we covered the current collector with the mixture of LiMn₂O₄ particle, conductive agents and binders, and then deposited an aluminum film onto it by vacuum evaporation technique. Both of the pristine electrode and the modified one were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and charge-discharge tests. The results of SEM and XRD demonstrate that the aluminum film was formed successfully onto the positive electrode. And the charge-discharge tests show that the capacity retention of pristine electrode and modified one are 63.7% and 93.5% at C/2 rate in the voltage range of 3.5-4.3 V after 200 cycles, respectively. The modified electrode also shows better rate capability in comparison with the pristine one. The improved cycling stability is attributed to the minimizing of Mn dissolution into electrolyte solution and the good electronic conductivity of deposited aluminum film.     

Thin film thickness step gauge

The Blodgett-Langmuir technique is used to deposit multilayer films of barium stearate on EDF glass. The thickness of the film varies in steps of 10 monolayers, and the thickness of each monolayer is about 25 Å. When viewed in white light at near normal incidence vivid interference colours are seen in reflection, with good contrast between adjacent steps. The reliability of the step gauge is tested for dielectric films of MgF₂.     

Energy and elastic constants of lithium and aluminium

In the proposed model of the fourth order in the pseudopotential including the distortion effects of Fermi surface and the energies of the ground state, elastic constants of the second and third orders of lithium and aluminium are calculated. The agreement with the experiment is rather better than in the second order models.     

Thin film solid oxide fuel cells

We have investigated the deposition of 91% ZrO₂ − 9% Y₂O₃ thin films by a variety of sputtering techniques for the application as electrolytes in thin film solid oxide fuel cells. The deposition by RF sputtering was accomplished by using an oxide target of the desired composition. The deposition rate in these initial tests was limited to 0.5 μm/hr and the morphology of the film was substantially modified by deposition rate and substrate temperature. Using DC magnetron sputtering we deposited metallic films from a metallic target with the desired chemical composition. We introduced oxygen into the sputtering chamber to reactively deposit the desired 91% ZrO₂ − 9% Y₂O₃ thin films; however, we encountered problems with target oxidation and growth rate reproducibility. We subsequently demonstrated that controlled oxidation of the metallic films could result in adhering, non porous yttria stabilized zirconia films. Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996     

Thin film optical components duplication method

A method which permits duplication of thin film optical components is described. A metallic master fabricated from an original recording on photoresist, is used to make numerous copies by embossing a sheet of a non-expensive plastic material. Some examples are given to illustrate the method.     

Diffusion in the aged aluminium film on iron

Metallic coatings of many types can be applied to steel to provide outstanding, long-term corrosion protection. A thin Al film is studied at an Fe substrate by the molecular dynamics method at temperatures ranging from 300 K to 1173 K. Al atoms are found to penetrate the Fe matrix at a temperature of 873 K. The potential energy of the system changes step-like at a temperature of 1173 K. At such temperature mean square atomic displacement significantly changes. The behaviors of the Al and Fe diffusion coefficients are mainly determined by the temperature dependence of the diffusion activation energy.     

Characterization of thin film lithium electrode materials

Thin rf-sputtered films of Li₄Fe_0.5±xTi_4.5±yO_11.75±z, Li₄Co_0.5±xTi_4.5±yO_11.5±z, Li₄Ti_5±xO_12±y, LiCo_1±xO_2±y and C were investigated by X-ray diffraction, thickness and weight determination, ICP/AAS, EDX and coulometric titration experiments employing the following liquid electrolytes (PC:EC:DMC=1:1:3, 1 M LiPF₆), (PC:DEC=1:4, 1 M LiPF₆), (EC:DMC=1:1, 1 M LiPF₆), (PC:DME=1:1, 1 M LiClO₄) and (γ-buthyrolactone, 1M LiClO₄). For comparison, cold isostatically pressed monolithic pellets of Li₄Fe_0.5Ti_4.5O_11.75, Li₄Co_0.5Ti_4.5O_11.5 and Li₄Ti₅O₁₂ were examined. The slope of the coulometric titration curves depends strongly on the employed liquid electrolyte. In the case of thin films, the stoichiometric width of the liquid electrolyte salt may have an additional impact on the results.     

自持铝薄膜的工艺和特性研究

铝薄膜在像管中起重要作用。为了提高像管的性能 ,需要对自持铝薄膜的特性加以研究。利用静电贴膜技术制备了自持铝薄膜 ,测量了 5 0nm厚自持铝薄膜入射面的背散射系数和二次发射系数以及出射面的一次电子透射系数和二次发射系数。对于高能一次入射电子 ,自持铝薄膜的背散射系数很小 ,透射系数很大 ,二次发射系数较小。自持铝薄膜在本质上不影响像管的MTF ,由其出射面发射的二次电子对像管亮度有增强作用     

Thin layers of aluminium: A molecular orbital study

Molecular beam epitaxy has been used to prepare thin layers (200 nm thickness) of aluminium grown either on aluminium or gallium arsenide substrates; their He(I) and He(II) photoelectron spectra have been recorded. The quasirelativistic CNDO/1 method has been applied to investigate the band structure of {Al}₁₇₂, {Al}₂₈₄ and {Al}₄₂₄ clusters obtained by a duplication of the unit cell: the DOS profiles and their projections were generated. These data were correlated with the periodic crystal orbitals of the EHT quality. The first excitation energy serves as a better estimate of the vanishing energy gap showing thus a metallic character of aluminium.     

Thin film mixtures synthesized by cross-beam PLD

Fabrication of metastable binary solid state film mixtures with continuously variable composition by asymmetric cross-beam PLD is demonstrated. In this technique, the materials are mixed directly in the intersection region of colliding plasmas of individual target materials. This technique can be advantageous for synthesis of solid state quasi-solutions of partially miscible materials, where one can expect interesting mechanic properties and magnetic transformations.     

Thin film semiconductor islands and numerical experiment

The distribution functions of island nuclei of germanium melt drops on Si(100) substrate over lateral sizes and heights in the presence of a surface linear defect are obtained in a numerical experiment simulating the initial stage of the first-order phase transition. A similar model of heterogeneous condensation of silicon carbide vapor is discussed. Quasi-linear kinetic partial differential equations are solved by the efficient numerical method of stochastic analogue of nonequilibrium processes. The Volmer-Weber mechanism of cluster formation from melt islands, their crystallization, and island structure formation on the substrate are considered.     

Fabrication and lithium electrochemistry of InSe thin film

InSe thin film has been successfully fabricated by pulsed-laser deposition method. Electrochemical behavior of Li/InSe cell has been investigated by Galvanostatic cycling and cyclic voltammetry measurements for the first time. The reversible capacity of InSe electrode of 410 mAh/g with the volumetric capacity of about 3302 mAh/cm³ was achieved at a current density of 0.05 mA/cm². By using XRD and XPS measurements, both alloying/de-alloying processes and selenidation/reduction processes were revealed during the electrochemical cycling of InSe thin film electrode. InSe was found to be a novel candidate of anode materials for rechargeable lithium batteries.     

Thin film magnetoelectric composites near spin reorientation transition

We report the use of a magnetic instability of the spin reorientation transition type to enhance the magnetoelectric sensitivity in magnetostrictive-piezoelectric structures. We present the theoretical study of a clamped beam resonant actuator composed of a piezoelectric element on a passive substrate actuated by a magnetostrictive nanostructured layer. The experiments were made on a polished 150 μm thick 18×3 mm² lead zirconate titanate (PZT) plate glued to a 50 μm thick silicon plate and coated with a giant magnetostrictive nanostructured Nx(TbCo_{2 5nm}/FeCo_5nm) layer. A second set of experiments was done with magnetostrictive layer deposited on PZT plate. Finally, a film/film structure using magnetostrictive and aluminium nitride films on silicon substrate was realized, and showed ME amplitudes reaching 30 V Oe⁻¹ cm⁻¹. Results agree with analytical theory.     

Thin film properties by facing targets sputtering system

In this study, film thickness distribution and c-axis crystalline orientation of deposited thin films were studied after preparing Co–Cr thin films, a promising ultra-high density perpendicular magnetic recording media, with a facing targets sputtering (FTS) apparatus. Electrical discharge characteristics needed for the optimum operation of sputter device was also studied in order to prepare thin films of superior c-axis crystalline orientation with FTS method (apparatus) in which thin film of fine quality can be formed because temperature increase of substrate due to the bombardment of high-energy particles can be restrained.As a result of the study, it is confirmed that the FTS method can give stable working under broad magnetic field and range of gas pressure and stable electrical discharge under low Ar gas pressure. Film thickness of prepared thin film shows fairy regular distribution and could obtain good thin films whose dispersion angle of c-axis crystalline orientation is about 3.5°.     

Thin cadmium sulphide film for radiative cooling application

The present work reports the possibility of a specific shield (CdS) to provide passive cooling for the purpose of reducing the use of classical active method. The ideal radiation shield would completely block solar radiation, but allow complete transmission in the “atmospheric-window” region.Chemical solution deposition of the thin film CdS (1 mm) for radiative cooling is described and optical properties of the thin film were measured by an OL-750 Spectroradiometer. The radiative properties of the shield improved optical properties of cooling purposes; which indicates that it has very low IR band reflectance and is transparent across the full 8-13 μm.     

Thin film arrays of weakly coupled superconducting particles

Thin film, macroscopic arrays of superconducting particles 100–10,000 Å in diameter can be produced by evaporating the superconductor in a gas at low pressure. The arrays have a critical supercurrent, I_c, which is a sensitive, multiply periodic function of the applied magnetic field. A simple model of multiple current paths through the array is proposed to explain both this observation and the general shape of the current-voltage characteristics.     

Sulphide based anode material for lithium rechargeable battery

In this study, lead sulphide (PbS) was prepared by the chemical bath deposition technique. The sample was characterized by X-ray diffraction (XRD), Energy Dispersive Analysis of X-rays (EDAX) and cyclic voltammetry. EDAX spectrum shows peaks attributable to lead and sulphur. The EDAX analysis also shows that the prepared sample is stoichiometric. Cyclic voltammetry experiments were recorded at 100 mV·s⁻¹ and 400 mV·s⁻¹ scan rates. Results show that the rate controlling electrochemical reaction is electron transfer. The presence of redox waves shows that the lithium intercalation and deintercalation can occur as a result of lattice expansion in PbS. There were no differences in the PbS XRD data before and after the cyclic voltammetry experiments indicating that the PbS structure is not modified upon lithium ion intercalation and deintercalation in PbS. The discharge characteristics for 35 cycles of the cell using the LiCoO₂/PbS couple is presented indicating the possible development of such materials as anode in lithium ion cells.