Thermodynamic activity of magnesium in several highly-solvating liquid alloys

Eckert, Charles A.; Irwin, Robert B.; Smith, Jeffery S.

doi:10.1007/bf02654364

Cited by 51 publications

(32 citation statements)

References 18 publications

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“…The theoretical cell EMF was calculated from data in the literature. 11 with the measured solution resistance and observed masstransport limitations. The operating efficiency could be improved by reducing the thickness of the electrolyte or operating at lower current density.…”

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confidence: 56%

“…When the cell was heated above the melting point of the molten salt, cell open-circuit voltages were found to stabilize at ∼0.44 V, consistent with thermodynamic data. 11 The cells were electrochemically characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using a two-electrode electrochemical setup with the negative electrode (Mg) as the counter electrode/reference electrode and the positive electrode (Sb) as the working electrode. The cells exhibited negligible charge-transfer overpotentials, as demonstrated by the linearity of the current−voltage relationship in the CV scans and the absence of an obvious semicircle in the EIS scans.…”

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confidence: 99%

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Magnesium–Antimony Liquid Metal Battery for Stationary Energy Storage

et al. 2012

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Batteries are an attractive option for gridscale energy storage applications because of their small footprint and flexible siting. A high-temperature (700°C) magnesium−antimony (Mg||Sb) liquid metal battery comprising a negative electrode of Mg, a molten salt electrolyte (MgCl 2 −KCl−NaCl), and a positive electrode of Sb is proposed and characterized. Because of the immiscibility of the contiguous salt and metal phases, they stratify by density into three distinct layers. Cells were cycled at rates ranging from 50 to 200 mA/cm 2 and demonstrated up to 69% DC−DC energy efficiency. The self-segregating nature of the battery components and the use of low-cost materials results in a promising technology for stationary energy storage applications.L arge-scale energy storage is poised to play a critical role in enhancing the stability, security, and reliability of tomorrow's electrical power grid, including the support of intermittent renewable resources. 1 Batteries are appealing because of their small footprint and flexible siting; however, conventional battery technologies are unable to meet the demanding low-cost and long-lifespan requirements of this application.A high-temperature (700°C) magnesium−antimony (Mg||Sb) liquid metal battery comprising a negative electrode of Mg, a molten salt electrolyte (MgCl 2 −KCl−NaCl), and a positive electrode of Sb is proposed (Figure 1). Because of density differences and immiscibility, the salt and metal phases stratify into three distinct layers. During discharge, at the negative electrode Mg is oxidized to Mg 2+ (Mg → Mg 2+ + 2e − ), which dissolves into the electrolyte while the electrons are released into the external circuit. Simultaneously, at the positive electrode Mg 2+ ions in the electrolyte are reduced to Mg (Mg 2+ + 2e − → Mg Sb ), which is deposited into the Sb electrode to form a liquid metal alloy (Mg−Sb) with attendant electron consumption from the external circuit (Figure 2 where R is the gas constant, T is temperature in Kelvins, F is the Faraday constant, a Mg(in Sb) is the activity of Mg dissolved in Sb, and a Mg is the activity of pure Mg.Recent work on self-healing Li−Ga electrodes for lithium ion batteries has demonstrated the appeal of liquid components. 2 While solid electrodes are susceptible to mechanical failure by mechanisms such as electrode particle cracking, 3 these are inoperative in liquid electrodes, potentially endowing cells with unprecedented lifespans. The self-segregating nature of liquid electrodes and electrolytes could also facilitate inexpensive manufacturing of a battery so constructed. However, there do not appear to be economical materials options that exist as liquids at or near room temperature.Previous work with elevated-temperature liquid batteries demonstrated impressive current density capabilities (>1000 mA/cm 2 when discharged at 0 V) with a variety of chemistries. 4−7 However, that work generally used prohibitively expensive metalloids (such as Bi and Te) as the positive electrode. The resulting cells exhibited...

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Magnesium–Antimony Liquid Metal Battery for Stationary Energy Storage

et al. 2012

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“…In the present study, the standard entropy of formation, f S • , of SnMg 2 , which is the only intermetallic compound in the Sn-Mg binary system [1], was measured. Eldridge et al [2], Egan [3], Eckert et al [4] and Moser et al [5] measured the activity, a, of Sn [2,4,5] and Mg [2][3][4][5] in the liquid phase of the Sn-Mg binary system by an isopiestic method [2] and electromotive method (EMF) [3][4][5]. Ogawa et al [ [9], and Zn 13 La [10], and the oxide NiMoO 4 [11] were precisely determined by measuring C p from near absolute zero (2 K) to 300 K by the recently developed method of relaxation calorimetry [12][13][14].…”

Section: Introductionmentioning

confidence: 98%

Standard entropy of formation of SnMg2 at 298K

Morishita

Kôyama

2005

Journal of Alloys and Compounds

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“…The surface composition was assumed to reach 10 wt% Mg in a short time after the electrolysis was commenced and remained as constant at that level through the experiment due to diffusion to the lower parts of the Mg-Pb cathode. The corresponding magnesium activity coefficient was taken as 0.1808 [9] and Mg activity was calculated as 0.090 at the upper surface of the cathode where the deposition took place. The value of mean theoretical decomposition voltage, E th , was calculated as −2.65 V from Eqs.…”

Section: Calculation Of Experimental Datamentioning

confidence: 99%