Batteries, lithium

The SEI is an inhomogeneous film which is composed of various reduction products and results from the chemical reaction between lithium and an electrolyte solution. The SEI plays the key role in lithium ion insertion-deinsertion and the electrochemical processes at the interface. However, Raman spectroscopy is rarely employed to investigate SEI layers 

Silver, which is one of the best SERS-active substrates, can be used as the positive electrode anode for lithium batteries since, when the battery is discharged, it is converted to 

Although difficulties in studying electrodes for lithium batteries have hindered a wider application of SERS, time-resolved Raman (or SERS) measurements of the changes of bulk materials and interfacial composition, the spatial-resolved confocal Raman observation of inhomogeneous surfaces could be of great interest. See [112] for a recent review. 

By placing a very pure lithium-metal foil as anode element and a lithium salt in a nonaqueous solution as electrolyte, a new generation of electrochemical generators was bom in the mid-1960s. Basically, the charge transport is identical to nickel-metal hydride (Ni-MH) or nickel-cadmium (Ni-Cd) batteries, except that Li ions are created by the simple reaction 

Primary and secondary lithium batteries using a nonaqueous electrolyte, exhibit higher energy density than aqueous electrolyte-based batteries due to the cell potential higher than 1.23 V, the thermodynamic limitation of water at 25 °C. The excellent performances of nonaqueous lithium batteries may meet the need for high power batteries in micro-devices, portable equipment, and even electrical vehicles. 

Lithium does not exist in the form of pure metal in nature due to a very high reactivity with air, nitrogen and water. It is extracted from ore or brine salt marsh 

FIGURE 10.6 CV of a l.iM 11204 electrode (surface density, 5 mg/cm ) in 1 M LiAsFy/ (ethylene carbonate + dimethyl carbonate). Potential scan rate, 0.0.5 mV/sec. (From Sinha and Munichandraiah, 2008. J. Solid State Electrochem. 12, 1619-1627, with permission from Springer.) 

In the case of pyrite batteries, Strauss et al. (2002) proposed a multistep mechanism for the charge-discharge of pyrite in polymer electrolytes in the temperature range 90-135°C. In the fust cycle, the reduction of pyrite occurs in two steps  

FIGURE 10.10 Schematics for charge solid-phase transitions in a pyrite-based composite cathode as described by Strauss et al. (2002). 

This step continues until all iron particles electrically connected to the current collector react with Li2S particles. This produces a thickening of the intermediate layer of Li2FeS2. When a given threshold thickness is reached, a potential jump appears, 

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Because of the special stabiHty of the hexafluoroarsenate ion, there are a number of appHcations of hexafluoroarsenates. For example, onium hexafluoroarsenates (33) have been described as photoinitiators in the hardening of epoxy resins (qv). Lithium hexafluoroarsenate [29935-35-1] has been used as an electrolyte in lithium batteries (qv). Hexafluoroarsenates, especially alkaH and alkaline-earth metal salts or substituted ammonium salts, have been reported (34) to be effective as herbicides (qv). Potassium hexafluoroarsenate [17029-22-0] has been reported (35) to be particularly effective against prickly pear. However, environmental and regulatory concerns have severely limited these appHcations. 

The metallic salts of trifluoromethanesulfonic acid can be prepared by reaction of the acid with the corresponding hydroxide or carbonate or by reaction of sulfonyl fluoride with the corresponding hydroxide. The salts are hydroscopic but can be dehydrated at 100°C under vacuum. The sodium salt has a melting point of 248°C and decomposes at 425°C. The lithium salt of trifluoromethanesulfonic acid [33454-82-9] CF SO Li, commonly called lithium triflate, is used as a battery electrolyte in primary lithium batteries because solutions of it exhibit high electrical conductivity, and because of the compound s low toxicity and excellent chemical stabiUty. It melts at 423°C and decomposes at 430°C. It is quite soluble in polar organic solvents and water. Table 2 shows the electrical conductivities of lithium triflate in comparison with other lithium electrolytes which are much more toxic (24). 

Uses. The largest use of lithium metal is in the production of organometaUic alkyl and aryl lithium compounds by reactions of lithium dispersions with the corresponding organohaHdes. Lithium metal is also used in organic syntheses for preparations of alkoxides and organosilanes, as weU as for reductions. Other uses for the metal include fabricated lithium battery components and manufacture of lithium alloys. It is also used for production of lithium hydride and lithium nitride. 

Lithium Bromide. Lithium biomide [7550-35-8] LiBi, is piepaied from hydiobiomic acid and lithium carbonate oi lithium hydroxide. The anhydrous salt melts at 550°C and bods at 1310°C. Lithium bromide is a component of the low melting eutectic electrolytes ia high temperature lithium batteries. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

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... 

Electronic and Electrical Applications. Sulfolane has been tested quite extensively as the solvent in batteries (qv), particularly for lithium batteries. This is because of its high dielectric constant, low volatUity, exceUent solubilizing characteristics, and aprotic nature. These batteries usuaUy consist of anode, cathode polymeric material, aprotic solvent (sulfolane), and ionizable salt (145—156). Sulfolane has also been patented for use in a wide variety of other electronic and electrical appHcations, eg, as a coil-insulating component, solvent in electronic display devices, as capacitor impregnants, and as a solvent in electroplating baths (157—161). 

Health nd Safety Factors. Thionyl chloride is a reactive acid chloride which can cause severe bums to the skin and eyes and acute respiratory tract injury upon vapor inhalation. The hydrolysis products, ie, hydrogen chloride and sulfur dioxide, are beheved to be the primary irritants. Depending on the extent of inhalation exposure, symptoms can range from coughing to pulmonary edema (182). The LC q (rat, inhalation) is 500 ppm (1 h), the DOT label is Corrosive, Poison, and the OSHA PEL is 1 ppm (183). The safety aspects of lithium batteries (qv) containing thionyl chloride have been reviewed (184,185). 

The physical picture in concentrated electrolytes is more apdy described by the theory of ionic association (18,19). It was pointed out that as the solutions become more concentrated, the opportunity to form ion pairs held by electrostatic attraction increases (18). This tendency increases for ions with smaller ionic radius and in the lower dielectric constant solvents used for lithium batteries. A significant amount of ion-pairing and triple-ion formation exists in the high concentration electrolytes used in batteries. The ions are solvated, causing solvent molecules to be highly oriented and polarized. In concentrated solutions the ions are close together and the attraction between them increases ion-pairing of the electrolyte. Solvation can tie up a considerable amount of solvent and increase the viscosity of concentrated solutions. 

Lithium batteries must use nonaqueous electrolytes, usually combinations of solvents, for stabiUty because lithium reacts readily with water. Many of... 

A second type of soHd ionic conductors based around polyether compounds such as poly(ethylene oxide) [25322-68-3] (PEO) has been discovered (24) and characterized. These materials foUow equations 23—31 as opposed to the electronically conducting polyacetylene [26571-64-2] and polyaniline type materials. The polyethers can complex and stabilize lithium ions in organic media. They also dissolve salts such as LiClO to produce conducting soHd solutions. The use of these materials in rechargeable lithium batteries has been proposed (25). 

Much analytical study has been required to estabHsh the materials for use as solvents and solutes in lithium batteries. References 26 and 27 may be consulted for discussions of electrolytes. Among the best organic solvents are cycHc esters, such as propylene carbonate [108-32-7] (PC), C H O, ethylene carbonate [96-49-1] (EC), C H O, and butyrolactone [96-48-0] and ethers, such as dimethoxyethane [110-71-4] (DME), C H q02, the glymes,... 

A second class of important electrolytes for rechargeable lithium batteries are soHd electrolytes. Of particular importance is the class known as soHd polymer electrolytes (SPEs). SPEs are polymers capable of forming complexes with lithium salts to yield ionic conductivity. The best known of the SPEs are the lithium salt complexes of poly(ethylene oxide) [25322-68-3] (PEO), —(CH2CH20) —, and poly(propylene oxide) [25322-69-4] (PPO) (11—13). Whereas a number of experimental battery systems have been constmcted using PEO and PPO electrolytes, these systems have not exhibited suitable conductivities at or near room temperature. Advances in the 1980s included a new class of SPE based on polyphosphazene complexes suggesting that room temperature SPE batteries may be achievable (14,15). 

The most important rechargeable lithium batteries are those using a soHd positive electrode within which the lithium ion is capable of intercalating. These intercalation, or insertion, electrodes function by allowing the interstitial introduction of the LE ion into a host lattice (16,17). The general reaction can be represented by the equation ... 

Boron Triiodide. There are no large-scale commercial uses of boron ttiiodide. It can cleave ethers without affecting aldehyde groups and thus finds use in the synthesis of the antibiotic fmstulosin (115,116). BI is used to prepare Snl, Sbl, and Til (117) in 99—100% yield. It is used to clean equipment for handling UE (118) and in the manufacture of lithium batteries (119). 

About 65% of the lithium is used as a ceU-bath additive in aluminum production and in ceramics and glass. Lithium batteries enjoy increasing popularity leading to steady growth in this market. Other uses are in lubricants and synthetic mbber (46). Since lithium is a light, strong metal, it finds apphcations in aerospace metals and alloys where a light metal is needed (see Lithiumand lithium compounds). 

It is claimed that the cured materials may be used continuously in air up to 300°C and in oxygen-free environments to 400°C. The materials are of interest as heat- and corrosion-resistant coatings, for example in geothermal wells, high-temperature sodium and lithium batteries and high-temperature polymer- and metal-processing equipment. 

J.R. Dahn, A.K. Sleigh, Hang Shi, B.W. Way, W.J. Weydanz, J.N. Reimers, Q. Zhong, and U. von Sacken, Carbons and Graphites as Substitutes for the Lithium Anode , in Lithium Batteries, G. Pistoia, Elsevier, North Holland (1993). 

S. Hossain, Rechargeable Lithium Batteries (Ambient temperature) , in Handbook of Batteries, 2nd edition, D. Linden, McGraw-Hill Inc. (1995). 

Security type attache cases incorporating lithium batteries and/or pyrotechnic material Selenium nitride Silver acetylide (dry)... 

The loading and unloading of bulk flammable liquids and gases at harbours and inland waterways Lithium batteries... 

Lithium-Ion Cells. Lithium-ion cells and the newer alternative, lithium-ion-polymer, can usually run much longer on a charge than comparable-size Nicad and nickel-metal hydride batteries. Usually is the keyword here since it depends on the battery s application. If the product using the battery requires low levels of sustained current, the lithium battery will perform very well however, for high-power technology, lithium cells do not perform as well as Nicad or nickel-metal hydride batteries. 

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