Lithium, metallic negatives

Initial development of ambient secondary lithium batteries was based on the primary lithium systems described in Chapter 4, consisting of a lithium metal negative, a non-aqueous lithium ion conducting electrolyte and a positive electrode material which could undergo a reversible electrochemical reaction with lithium ions ... 

As discussed below, there are problems with morphological changes and passivation reactions at lithium metal negative electrodes in secondary cells, which reduce cycle life and the practical energy density of the system, and may in some circumstances introduce safety hazards. A more recent development involves the replacement of the lithium metal anode by another insertion compound, say C Dm. In this cell, the electrochemical process at the negative side, rather than lithium plating and... 

Cells with lithium metal negative plates... 

This approach has been adopted by the Battery Division of Tadiran Ltd in Israel which is producing a rechargeable lithium battery under the trade name of Tadiran in-charge . This battery, manufactured in a standard A A size, uses a lithium metal negative, a lithiated manganese oxide positive... 

The Danish company Danionics has also developed LPB prototypes under EU contract using a lithium metal negative, a polymer gel electrolyte and a V60J3 positive. The cells had the form... 

Polyaniline is frequently used in r.b.s with lithium negative electrodes. However, in the course of the development of a commercialized system (Seiko/Bridgestone), there have only been a few examples with true lithium-metal negative electrodes, but many for the more practical LiAl alloy electrodes. The redox processes of RANI are basically the same in aqueous electrolytes and in Li -containing organic solutions. 

Thus, in analogy with the monomer quinone/hydroquinone redox couple, two electrons per monomer unit are assumed to be transferred finally. Examples for lithium metal negative electrodes in combination with PANI are reported in [508-510]. Details of the preparation of PANI positive electrodes are given in the patent literature (e.g., [358, 511-513]). 

The gel polymer network strucmre can be varied to that of combs and ladders by changing a kind of acrylate monomer. It also is possible to make an ion-conductive gel with a polyethylenic strucmre by cross-linking a difunctional acrylate compound such as polyethylene-glycol-diacrylate. Valence Inc. was not able to commercialize this battery, although it was proceeding with the development of polymer batteries that combined VjOg positive electrode and lithium metal negative electrode by this electrolyte. Table 21.1 shows the ionic conductivities of various gel polymer electrolytes. 

As with primary lithium batteries, a number of different approaches have been taken in the chemistry and design of rechargeable lithium batteries to obtain the desired performance characteristics. These are summarized in Fig. 34.1a for batteries with lithium metal negative electrodes (the anode during discharge) and in Fig. 34.1fc for batteries with other materials, such as lithium alloys and lithiated carbon. ... 

There is no obvious damage to the interface between the lithium metal electrode and polyphosphazene electrolytes during cycling. Electrochemical measurements of the Li/polyphosphazene electrolyte/Li battery show a cycling life of at least 600 times, demonstrating the good chemical stability of the electrolyte with the lithium metal negative electrode. 

At the time of writing, the solid-state alkali metal battery is by far the most important projected application of a polymer electrolyte. This is based on a thin film laminated structure containing a lithium-metal negative electrode, a polymer film electrolyte, and a positive electrode made of an oxidizing agent capable of inserting alkali ions into its structure (Figure 7). 

Lithium metal had few uses until after World War II, when thermonuclear weapons were developed (see Section 17.11). This application has had an effect on the molar mass of lithium. Because only lithium-6 could be used in these weapons, the proportion of lithium-7 and, as a result, the molar mass of commercially available lithium has increased. A growing application of lithium is in the rechargeable lithium-ion battery. Because lithium has the most negative standard potential of all the elements, it can produce a high potential when used in a galvanic cell. Furthermore, because lithium has such a low density, lithium-ion batteries are light. 

Due to its high energy density (3,860 mAh/g) and low voltage, lithium is the most attractive metal of the periodic table for battery application. Unfortunately lithium metal, and most of its alloys cannot be used in rechargeable batteries because of their poor cyclability. Therefore, lithium intercalation compounds and reversible alloys are among today s materials of choice for subject application. The most common active materials for the negative electrodes in lithium-ion battery applications are carbonaceous materials. The ability of graphitized carbonaceous materials to... 

Although the matrix may have a well-defined planar surface, there is a complex reaction surface extending throughout the volume of the porous electrode, and the effective active surface may be many times the geometric surface area. Ideally, when a battery produces current, the sites of current production extend uniformly throughout the electrode structure. A nonuniform current distribution introduces an inefficiency and lowers the expected performance from a battery system. In some cases the negative electrode is a metallic element, such as zinc or lithium metal, of sufficient conductivity to require only minimal supporting conductive structures. 

The LPB negative is commonly a lithium metal foil. The positive is based on a reversible intercalation compound, generally of the same type as those... 

LPB (lithium polymer battery) A cell (generally rechargeable) having a lithium foil negative, a metal oxide positive and a polymer electrolyte. 

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