Molten Salt Battery

A molten salt battery is a primary or secondary battery that uses a molten salt as its electrolyte. Molten salt batteries are a class of primary cell and secondary cell high-temperature electric battery. These types of batteries are used where high energy density and high power density are required. Their energy density and power density give them potential for use in electric vehicles. 

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A series of experiments have been undertaken to evaluate the relevant thermodynamic properties of a number of binary lithium alloy systems. The early work was directed towards determination of their behavior at about 400 °C because of interest in their potential use as components in molten salt batteries operating in that general temperature range. Data for a number of binary lithium alloy systems at about 400 °C are presented in Table 1. These were mostly obtained by the use of an experimental arrangement employing the LiCl-KCl eutectic molten salt as a lithiumconducting electrolyte. 

Two earlier reviews were published on high temperature cells and batteries based on molten salt and solid electrolytes. The first one (69) describes the Li/Cl2 cells, particularly the LiA.l/LiCl-KCl/Cl2 cell with gaseous CI2. Li cells with chalcogenides as cathode materials are mentioned, as well as some details of construction. This review, and the 26 references attached to it, reflects the state of the Li molten salt batteries to the end of 1970 (69). The second review (70), prepared two years later is more comprehensive. It discusses in detail some theoretical problems, the thermodynamics and rate processes in electrochemical cells, and presents tables and... 

The Other Five Candidates. All the molten salt SBs reviewed above have either a Li anode or a lithium alloy, one in which Li prevails quantitatively. As to the other 5 light metals they are seldom mentioned in the literature as candidates for anodes in these SBs, except Al. In (82) it is stated that molten salt batteries with Ca or Mg anodes yield only a small proportion of their theoretical energy because (a) Ca anodes react chemically with the electrolyte, and (b) both Ca and Mg anodes are passivated at high current drains, becoming coated with resistive films of solid salts. In a melt containing Li salts, Ca replaces Li ions by the displacement reaction Ca + 2LiCl = CaCl2 + 2Li. 

In spite of the great acceleration in battery development since the 1970s, there is still a large gap between the energy storage density readily available (about 100 W hr kg-1) and the theoretical maxima. The latter (see Fig. 13.51) reaches about 500 W hr kg-1 for cells using aqueous solutions at room temperature, and 2000 W hr kg-1 for the high-temperature (molten salt) batteries (Fig. 13.52). 

Interesting potential applications of molten salts are electroplating and electrorefining of refractory metals and rare earth metals. Electrowinning of titanium has been tested on a pilot scale. Electrodeposition of refractory compounds like TiB2 has also been demonstrated. Due to space limitations these more exotic applications of molten salts will not be treated here. However, short chapters on molten salt batteries and fuel cells are included. 

Swinkels D. A. J., Molten Salt Batteries and Fuel Cells in Advances in Molten Salt Chemistry, vol. I, J. Braunstein, G. Mamantov, G. P. Smith, eds., Plenum Press, New York, 1971, p. 165. 

Marassi R., Zamponi S., Berrettoni M., Molten Salt Batteries in Molten Salt Chemistry. An Introduction and Selected Applications, G. Mamantov, R. Marassi, eds., Reidel, Dordrecht, Boston, 1987, p. 491. 

Fujiwara, S., Kato, R, Watanabe, S., Inaba, M., and Tasak, A. (2009). New iodide-based molten salt systems for high temperature molten salt batteries./ Pow. Source., 194, pp. 1180-1183. 

The second molten salt battery to have received detailed attention is the lithium/ iron sulphide battery. During discharge, the negative electrode reaction is the dissolution of Hthium from a lithium/aluminium alloy (10—20% Li), while the positive electrode reaction is the reduction of iron disulphide which occurs in stages... 

Molten salt battery. Reserve battery. Fastest charging, largest and lightest batteries. Battery capacity and discharging. 

Mamantov et al. (46) studied the oxidation and reduction of sulfur, selenium, and iodine beginning in 1975, and later suggested sulfur (IV) as am oxidant in molten salt batteries. In 1980, Mamantov, Norvell, and Klatt carried out what appear to be the first spectroelectrochemical experiments in chloroaluminate melts using optically transparent electrodes to observe absorption spectra of species formed at the electrode (47). 

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