High-temperature batteries

Sudworth JL, Galloway RC (2009) Secondary batteries - high temperature systems - sodium-nickel chloride. In Jiirgen Garche, et al. Encyclopedia of electrochemical power sources. Amsterdam, The Nederland Elsevier BV, p 312... 

The metal oxo unit (M=0) is a fundamental constituent of both soluble molecular clusters and of complex solid materials. The practical interest in the molecular species reflects applications to homogeneous catalysis, heterogeneous catalysis, photocatalysis, electrocatalysis, magnetic materials, and materials synthesis. Likewise, the solid metal oxides exhibit a remarkable range of properties, with applications to high-temperature ferroelectrics, frequency doubling nonlinear optics, electrode materials in solid-state batteries, high-temperature superconductors, catalysis, sorption, and ceramics. 

Advanced rechargeable batteries can be classified into three main types advanced aqueous electrolyte systems, or as they are more-commonly known, flow batteries high-temperature systems and ambient-temperature lithium batteries. 

The materials developed to date, for instance, for rechargeable solid state batteries, high-temperature fuel cells and electrolyzers, smart windows, and environmental gas sensors are numerous, and while many exhibit positional or orientational disorder, an overwhelming number conducts by virtue of point defects, and the defect chemistry of these materials is the focus of this chapter. 

Uses and potential applications of fullerenes include antioxidants in personal care products, biopharmaceuticals, catalysts, organic solar cells, long-life batteries, high-temperature superconductors, and molecular magnets. 

Molten lithium fluoride is used in salt mixtures for an electrolyte in high temperature batteries (qv) (FLINAK) (20), and as a carrier in breeder reactors (FLIBE) (21) (see Nuclear reactors). 

Applications. Polymers with small alkyl substituents, particularly (13), are ideal candidates for elastomer formulation because of quite low temperature flexibiUty, hydrolytic and chemical stabiUty, and high temperature stabiUty. The abiUty to readily incorporate other substituents (ia addition to methyl), particularly vinyl groups, should provide for conventional cure sites. In light of the biocompatibiUty of polysdoxanes and P—O- and P—N-substituted polyphosphazenes, poly(alkyl/arylphosphazenes) are also likely to be biocompatible polymers. Therefore, biomedical appHcations can also be envisaged for (3). A third potential appHcation is ia the area of soHd-state batteries. The first steps toward ionic conductivity have been observed with polymers (13) and (15) using lithium and silver salts (78). 

Lithium Chloride. Lithium chloride [7447- 1-8], LiCl, is produced from the reaction of Hthium carbonate or hydroxide with hydrochloric acid. The salt melts at 608°C and bods at 1382°C. The 41-mol % LiCl—59-mol % KCl eutectic (melting point, 352°C) is employed as the electrolyte in the molten salt electrolysis production of Hthium metal. It is also used, often with other alkaH haHdes, in brazing flux eutectics and other molten salt appHcations such as electrolytes for high temperature Hthium batteries. 

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. 

Barium improves the performance of lead ahoy grids of acid batteries (see Batteries) (34). In the form of thin films, barium has been found to be a good high temperature lubricant on the rotors of anodes operating at 3500 rpm ia vacuum x-ray tubes (35). 

Self-Discharge Processes. The shelf life of the lead—acid battery is limited by self-discharge reactions, first reported in 1882 (46), which proceed slowly at room temperature. High temperatures reduce shelf life significantly. The reactions which can occur are well defined (47) and self-discharge rates in lead—acid batteries having immobilized electrolyte (48) and limited acid volumes (49) have been measured. 

Lithium—Aluminum/Metal Sulfide Batteries. The use of high temperature lithium ceUs for electric vehicle appUcations has been under development since the 1970s. Advances in the development of lithium aUoy—metal sulfide batteries have led to the Li—Al/FeS system, where the foUowing ceU reaction occurs. 

Sodium—Sulfur. The best known of the high temperature batteries is the sodium [7440-23-5]—s Aiu.i. [7704-34-9] Na—S, battery (66). The cell reaction is best represented by the equation ... 

Graphite fluoride continues to be of interest as a high temperature lubricant (6). Careful temperature control at 627 3° C results in the synthesis of poly(carbon monofluoride) [25136-85-0] (6). The compound remains stable in air to ca 600°C and is a superior lubricant under extreme conditions of high temperatures, heavy loads, and oxidising conditions (see Lubrication and lubricants). It can be used as an anode for high energy batteries (qv). 

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. 

None of the interesting materials just described are the direct ancestors of the present generation of ionic liquids. Most of the ionic liquids responsible for the burst of papers in the last several years evolved directly from high-temperature molten salts, and the quest to gain the advantages of molten salts without the disadvantages. It all started with a battery that was too hot to handle. 

The poor efficiencies of coal-fired power plants in 1896 (2.6 percent on average compared with over forty percent one hundred years later) prompted W. W. Jacques to invent the high temperature (500°C to 600°C [900°F to 1100°F]) fuel cell, and then build a lOO-cell battery to produce electricity from coal combustion. The battery operated intermittently for six months, but with diminishing performance, the carbon dioxide generated and present in the air reacted with and consumed its molten potassium hydroxide electrolyte. In 1910, E. Bauer substituted molten salts (e.g., carbonates, silicates, and borates) and used molten silver as the oxygen electrode. Numerous molten salt batteiy systems have since evolved to handle peak loads in electric power plants, and for electric vehicle propulsion. Of particular note is the sodium and nickel chloride couple in a molten chloroalumi-nate salt electrolyte for electric vehicle propulsion. One special feature is the use of a semi-permeable aluminum oxide ceramic separator to prevent lithium ions from diffusing to the sodium electrode, but still allow the opposing flow of sodium ions. 

Table 8. Specification of coin-type lithium-carbon monofluoride batteries for high-temperature range...

Lithium alloys have been used for a number of years in the high-temperature "thermal batteries" that are produced commercially for military purposes. These devices are designed to be stored for long periods at ambient temperatures before use, where their self-discharge kinetic be-... 

Underwriters Laboratories (UL) requires that consumer batteries pass a number of safety tests [3]. UL requires that a battery withstand a short circuit without fire or explosion. A positive temperature coefficient (PTC) device [4] is used for external short-circuit protection. The resistance of a PTC placed in series with the cell increases by orders of magnitude at high currents and resulting high temperatures. However, in the case of an internal short, e.g., if the positive tab comes lose and contacts the interior of the negative metal can, the separator could act as a fuse. That is, the impedance of the separator increases by two to three orders of magnitude due to an increase in cell temperature. 

Dry processes involve melting a polyolefin resin, extruding it into a film, thermal annealing, orientation at a low temperature to form micropore initiators, and then orientation at a high temperature to form micropores [9, 10]. The dry process involves no solvent handling, and therefore is inherently simpler than the wet process. The dry process involves only virgin polyolefin resins and so presents little possibility of battery contamination. 

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