Lithium films

There is IR evidence for the formation of Li2(C2) ( C=C at 1845 cm-1) by laser irradiation of lithium films containing carbonate groups.1... 

Attention in this chapter will be mainly focused on che reaction of tecrahydrofuran (THF) with thin lithium films vapor-deposited in UHV on clean polycrystalline Ag substrates. The techniques employed in this study included TPD, XPS and AES. A parallel study of THF adsorption on Li layers deposited on Au substrates is currently being pursued by Ms. Guorong Zhuang using FTIRRAS (Fourier Transform Reflection Absorption Infrared Spectroscopy) in this laboratory. 

Table 7.1. Quantitative microstructural characteristics of the niobate lithium film...

The advantage of polymer electrodes is that they can be easily shaped, allowing novel battery design. Polymer cells with poly(pyrrole) and lithium electrodes have been developed [13]. In the flat cell, the poly(pyrrole) and lithium films are sandwiched together, in the eylindrical cell, the two films are wound concentrically. Their energy per unit mass... 

FIGURE 11.13. Schematic representation of a lithium miorobattery. It is worth noting that the volume of the intercalation compound determines the cell capacity and that a buffer layer can be inserted between the lithium film and the solid electrolyte film to prevent chemical reaction. (From Julien, C. and Nazri, G.A., Solid State Batteries Materials Design and Optimization, Kluwer, Boston, 1994. With permission.)... 

The complexity of SEI formation is topped off with reactions of the electrolyte with contaminants and additives. Because of different reaction rates of all reactive components with lithium, which yield surface films of different quality, additives can be used to modify the surface films to highly conductive lithium films, preventing the components of the electrolyte from further decomposition. There are many successful examples of this approach in the open and patent literature, both for lithium anodes and also for lithiated carbon electrodes. 

One procedure makes use of a box on whose silk screen bottom powdered desiccant has been placed, usually lithium chloride. The box is positioned 1-2 mm above the surface, and the rate of gain in weight is measured for the film-free and the film-covered surface. The rate of water uptake is reported as u = m/fA, or in g/sec cm. This is taken to be proportional to - Cd)/R, where Ch, and Cd are the concentrations of water vapor in equilibrium with water and with the desiccant, respectively, and R is the diffusional resistance across the gap between the surface and the screen. Qualitatively, R can be regarded as actually being the sum of a series of resistances corresponding to the various diffusion gradients present ... 

Thin films (qv) of lithium metal are opaque to visible light but are transparent to uv radiation. Lithium is the hardest of all the alkaH metals and has a Mohs scale hardness of 0.6. Its ductiHty is about the same as that of lead. Lithium has a bcc crystalline stmcture which is stable from about —195 to — 180°C. Two allotropic transformations exist at low temperatures bcc to fee at — 133°C and bcc to hexagonal close-packed at — 199°C (36). Physical properties of lithium are Hsted ia Table 3. 

Selenium and selenium compounds are also used in electroless nickel-plating baths, delayed-action blasting caps, lithium batteries, xeroradiography, cyanine- and noncyanine-type dyes, thin-film field effect transistors (FET), thin-film lasers, and fire-resistant functional fluids in aeronautics (see... 

Liquid Cathode Cells. Liquid cathode cells were discovered at almost the same time as the successful soHd cathode cells. A strongly oxidising hquid such as SO2, was deterrnined to be suitable for direct contact with the strongly reducing lithium, because an excellent passivating film forms... 

Lithium as an anode in alkaline electrolyte has been considered in the battery system shown in Figure 29. Even though lithium reacts dkecdy with water, it was possible to operate the battery because of a protective lithium hydroxide film that forms on the anode. However, the film was not totally protective and units exhibited poor efficiency and were very complex. 

The heHcoidal stmcture of such Hquid crystals can be carried to the soHd state by cross-linking (119,120) or by careful evaporation of solvent (121,122). Underivatized ceUulose can also form ordered mesophases (123,124), and gel films precipitated from lithium chloride—dimethyl acetamide retain some mesophase stmcture (122). 

For smart cards, micro-robots and small precision instruments, thin laminated micro-cells are being developed. Some of these developmental thin-film devices—using an electrolyte of lithium, a copper cathode, and lithium again for the electrode—can charge and discharge up to 3 volts, and can be expected to tolerate up to 1,000 charge-and-discharge cycles. 

Films on lithium play an important part in secondary lithium metal batteries. Electrolytes, electrolyte additives, and lithium surface treatments modify the lithium surface and change the morphology of the lithium and its current efficiency [93],... 

While the initial surface species formed on lithium in alkyl carbonates consist of ROC02Li compounds, these species react with water to form Li,CO, C02, and ROH. This reaction gradually changes the composition of the surface films formed on... 

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