Ionic melts as solvents for electronic conductors

Dworkin, A. S.; Bronstein, H. R.; Bredig, Μ. A.

doi:10.1039/df9613200188

Cited by 47 publications

(46 citation statements)

References 6 publications

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“…15,16 Electronic conductivity in the electrolyte depends upon the solubility of Ca metal. 17 In our set-up with Ca-Bi as CE, the activity of Ca in Sb is lower than in Bi, providing a chemical short-circuit of Ca from Bi CE to Sb WE, leading to self-discharge of the WE. In contrast, the chemical dissolution of Ca-Sb alloys as ionic species can cause the loss of Sb WE, particularly on deep discharge, leading to coulombic capacity loss.…”

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confidence: 99%

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Ouchi

Kim

Ning

et al. 2014

J. Electrochem. Soc.

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The performance of a calcium-antimony (Ca-Sb) alloy serving as the positive electrode in a Ca Sb liquid metal battery was investigated in an electrochemical cell, Ca(in Bi) | LiCl-NaCl-CaCl 2 | Ca(in Sb). The equilibrium potential of the Ca-Sb electrode was found to lie on the interval, 1.2-0.95 V versus Ca, in good agreement with electromotive force (emf) measurements in the literature. During both alloying and dealloying of Ca at the Sb electrode, the charge transfer and mass transport at the interface are facile enough that the electrode potential varies linearly from 0.95 to 0.75 V vs Ca(s) as current density varies from 50 to 500 mA cm −2 . The discharge capacity of the Ca Sb cells increases as the operating temperature increases due to the higher solubility and diffusivity of Ca in Sb. The cell was successfully cycled with high coulombic efficiency (∼100%) and small fade rate (<0.01% cycle −1 ). These data combined with the favorable costs of these metals and salts make the Ca Sb liquid metal battery attractive for grid-scale energy storage. The liquid metal battery (LMB) has been shown to be an attractive potential solution to the problem of grid-level storage.1,2 The LMB comprises two liquid metal electrodes separated by a molten salt electrolyte that self-segregate into three liquid layers according to density and immiscibility. In the search for even lower-cost chemistries based on this formula, the Ca-Sb system became the focus of attention because Ca, thanks to its ubiquitous abundance, 3 offers high performance at a low price point. Previous measurements in this laboratory of the thermodynamics of liquid Ca-Sb alloys 4 revealed this system to be high-voltage (0.94-1.04 V) and low-cost (69 $ kWh −1 ). However, Ca is highly soluble in its salts 5 conferring such a high level of electronic conductivity that a battery fitted with a liquid Ca electrode would exhibit an unacceptably high self-discharge current. In this study we show how to suppress the Ca metal solubility in the molten salt electrolyte so as to make practical a Ca-Sb LMB.The literature indicates that the solubility of calcium metal is significantly reduced by alloying calcium with other metals to decrease its activity (a Ca ).5 Following this, one can envisage a Ca-Sb liquid metal battery as:where A is the negative electrode host and the electrolyte can be a solution of molten halide salts with calcium cation as the itinerant. The alloying of calcium with a more noble A metal such as magnesium desirably decreases the melting temperature of the negative electrode, reduces the reactivity of pure calcium metal, and decreases the solubility of calcium in the molten salt electrolyte while undesirably decreasing the cell voltage, 6 albeit an acceptably small amount. For the cell with Mg as the negative electrode host and Sb as the positive electrode, the half-cell reactions are negative : Ca(in Mg) = Ca 2+ + 2epositive : Ca 2+ + 2e − = Ca(in Sb) [3] and the resulting overall cell reaction is cell : Ca(in Mg) = Ca(in Sb).[4]On discharge, calcium...

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confidence: 99%

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Ouchi

Kim

Ning

et al. 2014

J. Electrochem. Soc.

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“…They have the same shape as for PrCl3 NaCl, PrCl3-KC1, and PrCl3-CaCl2 [7]. A comparison of the elec trical conductivity of molten LaCl3 with previous data [16][17][18][19] is given in Table 2.…”

Section: Resultsmentioning

confidence: 80%

Electrical Conductivity of Molten LaCl₃-NaCl, LaCl₃-KCl, and LaCl₃-CaCl₂

Fukushima

Iwadate

Andou

et al. 1991

Zeitschrift Für Naturforschung A

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The electrical conductivities (x's) of molten LaCl3-NaCl, LaCl3-KCl, and LaCl3-CaCl2 were measured at 893-1168 K, by a conventional ac technique and fitted by quadratic functions of temperature. They increase with increasing temperature and decrease with increasing mole fraction of LaCl3. The equivalent conductivities (A's) follow a linear relationship of In A vs. 1/T The A's of LaCl3-NaCl and LaCl3-KCl decrease drastically with increasing LaCl3 concentration. A of molten LaCl3 is smaller than that of molten CaCl2, in which the octahedral complex anion CaClg" is known to exist. It seems reasonable to assume that complex ions or cluster species such as LaCl^-and La2Cli!~ exist in molten LaCl3 and its mixture melts. Similar results, reported in a previous paper, were obtained for PrCl3-NaCl, PrCl3-KCl, and PrCl3-CaCl2.

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“…Thermodynamic arguments (vide infra) predict that a small but significant concentration of calcium metal will be in equilibrium with calcium carbide dissolved in molten calcium chloride and a known activity of carbon (usually fixed by the crucible material). The form taken by the calcium metal in solution in calcium chloride is uncertain but "F centers" or lower valent forms of calcium ions have been suggested for calcium chloride -calcium (1,2) and calcium fluoride -calcium melts (3).…”

Section: Introductionmentioning

confidence: 99%

The Determination of Calcium Carbide and its Dissociation Products in Fused Calcium Chloride

Aksaranan¹,

Dosaj²,

Morris³

et al. 1971

Can. J. Chem.

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The principal constituents in molten solutions of calcium carbide in calcium chloride have been determined. The analytical results were generally within order of magnitude agreement with calculations from thermodynamic data based upon a model in which the calciumcarbideis thought to be dissociated according to the equationOn a Btabli la nature des principaux constituants des solutions fondues de carbure de calcium dans le chlorure de calcium. Les rdsultats analytiques sont g6nCralement en accord tt I'intQieur d'une ordre de grandeur-avec les donnks thermodynamiques basks sur un modkle dans lequel on croyait que le carbure de calcium est dissociB suivant 1'Bquation

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Ionic melts as solvents for electronic conductors

Cited by 47 publications

References 6 publications

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Electrical Conductivity of Molten LaCl₃-NaCl, LaCl₃-KCl, and LaCl₃-CaCl₂

The Determination of Calcium Carbide and its Dissociation Products in Fused Calcium Chloride

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Ionic melts as solvents for electronic conductors

Cited by 47 publications

References 6 publications

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Calcium-Antimony Alloys as Electrodes for Liquid Metal Batteries

Electrical Conductivity of Molten LaCl3-NaCl, LaCl3-KCl, and LaCl3-CaCl2

The Determination of Calcium Carbide and its Dissociation Products in Fused Calcium Chloride

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Electrical Conductivity of Molten LaCl₃-NaCl, LaCl₃-KCl, and LaCl₃-CaCl₂