First-Principles Determination of Transference Numbers in Cryolitic Melts

Gheribi, Aïmen E.; Salanne, Mathieu; Zanghi, Didier; Machado, Kelly; Bessada, Catherine; Chartrand, Patrice

doi:10.1021/acs.iecr.0c02281

Cited by 5 publications

(4 citation statements)

References 46 publications

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“…In the absence of these electrostatic interactions, the ionic conductivity would be identical to the Nernst−Einstein conductivity. 31 So, the Haven ratio,…”

Section: ■ Discussionmentioning

confidence: 99%

“…From a microscopic point of view, the electrostatic interactions between the different ions play a major role in the electrical conductivity in molten carbonates. In the absence of these electrostatic interactions, the ionic conductivity would be identical to the Nernst–Einstein conductivity . So, the Haven ratio, defines the total effect of the electrostatic interactions on the conductivity.…”

Section: Discussionmentioning

confidence: 99%

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Speciation and Transport Properties in Molten Alkali Carbonates at High Temperature

et al. 2022

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We study structural and transport properties of different eutectic mixtures of molten carbonate used for the capture and valorization of CO 2 . Different techniques, such as NMR, PFG NMR, and electrical impedancemetry, were used to study Li 2 CO 3 −Na 2 CO 3 (52:48%mol), Li 2 CO 3 −K 2 CO 3 (62:38%mol), Li 2 CO 3 −K 2 CO 3 (40:60%mol), and Li 2 CO 3 −Na 2 CO 3 −K 2 CO 3 (43.5:31.5:25%mol) compositions at high temperature. The NMR measurements confirmed only the presence of anionic species CO 3 2−. No effect of composition or temperature on speciation was detected. From electrical conductivity and self-diffusion coefficients measurements, we have shown that the electrical conductivity of carbonates not only depends on the radius of the cations, but also depends on the electrostatic interaction between ions. With the addition of K 2 CO 3 in the carbonate mixture, the interaction between the charge carriers present in the liquid increases and results in a decrease of electrical conductivity. We have shown that the high solubility of CO 2 in compositions with high lithium carbonate content is associated with a high mobility of Li + cations.

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“…In the absence of these electrostatic interactions, the ionic conductivity would be identical to the Nernst−Einstein conductivity. 31 So, the Haven ratio,…”

Section: ■ Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Speciation and Transport Properties in Molten Alkali Carbonates at High Temperature

et al. 2022

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“…Indeed, Koishi et al 23 showed that the universal golden rule holds for molten NaCl as well. This strongly suggests that direct determination of the partial conductivities from the calculated electrical mobility values b EF is to be preferred over the approach by Gheribi et al 15,39,45 . It should be noted that negative effective transference numbers for cations have been reported in a few additional publications [46][47][48][49] .…”

Section: What Causes a High Conductivity?mentioning

confidence: 99%

Microscopic origins of conductivity in molten salts unraveled by computer simulations

Walz

Spoel

2021

Commun Chem

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Molten salts are crucial materials in energy applications, such as batteries, thermal energy storage systems or concentrated solar power plants. Still, the determination and interpretation of basic physico-chemical properties like ionic conductivity, mobilities and transference numbers cause debate. Here, we explore a method for determination of ionic electrical mobilities based on non-equilibrium computer simulations. Partial conductivities are then determined as a function of system composition and temperature from simulations of molten LiFαClβIγ (with α + β + γ = 1). High conductivity does not necessarily coincide with high Li+ mobility for molten LiFαClβIγ systems at a given temperature. In salt mixtures, the lighter anions on average drift along with Li+ towards the negative electrode when applying an electric field and only the heavier anions move towards the positive electrode. In conclusion, the microscopic origin of conductivity in molten salts is unraveled here based on accurate ionic electrical mobilities and an analysis of the local structure and kinetics of the materials.

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“…In Figure 17, we assume that the majority of the charge transfer is made by sodium cations and fluorine anions. In the literature, it is reported that about 90% of the charge is transferred by Na + ions and about 10% by F − ions [49][50][51][52][53]. The thermodynamic calculations are performed on a basis of 100 g of electrolyte.…”

Section: Simulation Of the Overall Electrochemical Processmentioning

confidence: 99%

On the Application of the FactSage Thermochemical Software and Databases in Materials Science and Pyrometallurgy

et al. 2020

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The discovery of new metallic materials is of prime importance for the development of new technologies in many fields such as electronics, aerial and ground transportation as well as construction. These materials require metals which are obtained from various pyrometallurgical processes. Moreover, these materials need to be synthesized under extreme conditions of temperature where liquid solutions are produced and need to be contained. The design and optimization of all these pyrometallurgical processes is a key factor in this development. We present several examples in which computational thermochemistry is used to simulate complex pyrometallurgical processes including the Hall–Heroult process (Al production), the PTVI process (Ni production), and the steel deoxidation from an overall mass balance and energy balance perspective. We also show how computational thermochemistry can assist in the material selection in these extreme operation conditions to select refractory materials in contact with metallic melts. The FactSage thermochemical software and its specialized databases are used to perform these simulations which are proven here to match available data found in the literature.

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First-Principles Determination of Transference Numbers in Cryolitic Melts

Cited by 5 publications

References 46 publications

Speciation and Transport Properties in Molten Alkali Carbonates at High Temperature

Speciation and Transport Properties in Molten Alkali Carbonates at High Temperature

Microscopic origins of conductivity in molten salts unraveled by computer simulations

On the Application of the FactSage Thermochemical Software and Databases in Materials Science and Pyrometallurgy

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