Current‐Induced Composition Gradients in Molten AgNO3 ‐ NaNO3: A Model System for the LiCl ‐ KCl Electrolyte of an Li/S Battery

Vallet, C. E.; Heatherly, D. E.; Sherman, Robert L.; Braunstein, J.

doi:10.1149/1.2123790

Cited by 11 publications

(29 citation statements)

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“…Later, these predictions were confirmed in several experiments with electrolytes contained in porous bodies that completely suppress or at least strongly damped any convective effects [46,47]. These experiments were performed not only with low-melting model systems (such as NaCl-KCl-AlCl 3 or AgNO 3 -NaNO 3 [46,47]), but even with LMB-relevant LiCl-KCl [48]. The observed concentration gradients are caused by the electrode reactions, i.e.…”

Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 65%

“…The authors predicted concentration gradients in mixed cation molten salts based on equations that did not include convection terms [43,44]. Later, these predictions were confirmed in several experiments with electrolytes contained in porous bodies that completely suppress or at least strongly damped any convective effects [46,47]. These experiments were performed not only with low-melting model systems (such as NaCl-KCl-AlCl 3 or AgNO 3 -NaNO 3 [46,47]), but even with LMB-relevant LiCl-KCl [48].…”

Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 93%

“…Although barely studied in LMBs, it is well known from literature that composition gradients play an important role in molten salt electrolytes. Such phenomena have been widely investigated by Braunstein and Vallet in several publications [43][44][45][46][47][48] who show that concentration gradients in molten salts can be significant. The authors predicted concentration gradients in mixed cation molten salts based on equations that did not include convection terms [43,44].…”

Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 99%

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Modeling Potential and Species Distribution in a Li||Bi Liquid Metal Battery Using the Finite Volume Method

et al. 2022

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To match the growing demand for grid scale energy storage in order to balance out renewable energies, the liquid metal battery (LMB) technology is highly promising. Key elements of these batteries are the liquid electrodes, which require LMBs operating at elevated temperatures. Hereby, the electrolyte can be liquid or solid state. Based on density differences, the battery is self-assembling since the components self-segregate when the system is heated. Additionally, many of the possible materials are earth-abundant and not expensive. This results in a very cost effective technology. Moreover, the molten electrodes feature superior kinetics and transport properties as well as high voltage efficiencies at high current densities. Otherwise, the liquidity has the disadvantage that high operating temperatures are necessary. Further, there is a risk of corrosion, self-discharge and short-circuiting. The latter makes the battery not applicable for portable applications [Kim, H. et al. Chem. Rev. 113 (3) (2013)]. Among all LMBs, the Li||Bi cell has been investigated to a large extend and therefore, most material properties are readily available. This is the reason why the present study focuses on this material pairing. A schematic of this cell during discharge is shown in figure 1a. Here, the anode metal Lithium is oxidized and the ion crosses the electrolyte layer. Then it alloys with the molten Bismuth. At charge, this process is reversed. A picture of a real cell can be found in figure 1b. Nevertheless, there are other very promising cell chemistries such as NaZn batteries [Xu, J. et al. J. Power Sources 332 (2016)]. For theoretical investigations and numerical simulations, electromagnetic fields, electrochemistry and fluid dynamics need to be considered. Coupling of the corresponding fundamental equations and the different regions in the battery is challenging. Further, there are multiple fluid flow phenomena – like surface instabilities, Tayler instability, electro-vortex flow, thermal convection,solutal convection or Marangoni convection [Kelley, D. H. and Weier, T. Appl. Mech. Rev. 70 (2) (2018)] – that might occur when the battery is operated. To determine the operating voltage of a cell, overpotentials need to be investigated. Generally, there are three types of overpotentials: the ohmic loss, the mass transfer and the charge transfer overpotential. However, the latter can be neglected [Newhouse, J. M. Ph.D. thesis, MIT (2014)]. Determining the ohmic overpotential is quite straightforward using Ohm’s law, while the concentration overpotential requires the calculation of the species distribution in the electrolyte and the positive electrode. The present study will focus on the electrochemical behavior of an all liquid Li||Bi battery and neglects fluid flow. Hereby, the whole cell is modeled using the parent-child-mesh technique from Weber et al. [Weber, N. et al. Computers & Fluids 168 (2018)]. This implies that the species distribution in the electrolyte and the distribution of the dissolved species in the cathode are calculated locally and the potential and current density distribution are calculated globally. The equations to solve are coupled between the used meshes. To account for the potential distribution, it is necessary to consider the electrochemical double layer at the electrode-electrolyte interfaces. Macroscopically, the latter can be described as a potential jump at both interfaces in accordance to the Nernst equation. Weber et al. [Weber, N. et al. Electrochim. Acta 318 (2019)] introduced to model this jump using a source term. In the present study, the approach to use internal jump boundary conditions for modeling the potential jump is proposed. To the best knowledge of the authors, species distributions in the electrolyte have not been investigated previously. When there is no mixing of the electrolyte of LMBs, concentration gradients of each species might be significant [Vallet, C. E. et al. J. Electrochem. Soc. 130 (12) (1983)]. Based on the solution for the species distribution, the potential jump at each interface can be calculated. Further, the charge transfer overpotentials can be obtained. The equations are solved quasi-one-dimensional using the finite volume method and are implemented in the open source library OpenFOAM. To validate this new approach, a comparative study with Comsol is performed. Lastly, an application case is simulated, which confirms that concentration layers in the electrolyte are indeed present. This is, for the case of an Li+ ion in a LiCl-KCl eutectic molten salt, exemplarily shown in figure 1d. Further, as it can be seen in figure 1c, the simulation is able to solve the potential distribution in the cell with respect to the potential jump at the interface. Acknowledgment: This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 963599. Figure 1

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Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 65%

Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 93%

Section: Liquid Metal Battery and Its Applicationmentioning

confidence: 99%

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Modeling Potential and Species Distribution in a Li||Bi Liquid Metal Battery Using the Finite Volume Method

et al. 2022

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“…First, the fundamental aspects of the Li-S batteries are discussed, followed by the emerging roles of the metal-based compounds and their interaction with the polysulfides. Furthermore, the strategies employed in the inhibition [35] 1988, [36] 2009, [37] 2010, [38] 2012, [39] 2015, [40] 2016, [41] 2017, [42] 2018, [43] 2019, [44] and 2020. [45] Reproduced with permission.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2. Number of a) yearly publications and b) citations from the year 2010 to 2020 with the topic keywords of "Li-S battery & cathode" in the Web of Science database, dated February 28, 2021. c) Timeline of the research on Li-S battery from the pioneering work in 1982 to the present: 1982,[35] 1988,[36] 2009,[37] 2010,[38] 2012,[39] 2015,[40] 2016,[41] 2017,[42] 2018,[43] 2019,[44] and 2020 [45]. Reproduced with permission [38].…”

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confidence: 99%

Lithium–Sulfur Battery Cathode Design: Tailoring Metal‐Based Nanostructures for Robust Polysulfide Adsorption and Catalytic Conversion

2021

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portable electronic devices such as laptops and mobile phones. However, with the increasing demand for clean energy and portable electronics, the energy densities powered by the LIB (≈300 mAh g −1 ) are beginning to reach the threshold limit and thus, leading to a need for an alternate environmentally friendly and more economical energy storage technology with higher energy densities. [1] One of the most promising candidates for the LIB replacement is the lithium-sulfur (Li-S) battery, which utilizes the redox reaction between sulfur and lithium. Compared to LIB and other metal-sulfur batteries (Figure 1a), Li-S batteries are profiled as a viable energy storage technology stemming from their high specific energy capacity of 1675 mAh g −1 and superior energy density of around 2670 Wh kg −1 . [1a-d,2] The elemental sulfur, which is used as the cathode material, also has a multitude of auspicious properties such as its inexpensiveness, environmentally friendliness, abundancy and non-toxicity. [2d,3] In addition, another emerging battery system is the metal-air battery, which is a half-open system that utilize oxygen from ambient air as the active cathode material. Thus, Li-S batteries are comparatively safer due to their enclosed system. Apart from that, the influence of CO 2 , H 2 O, and N 2 in ambient air can lead to chemical instability in metal-air batteries. [4] Taking Li-air batteries as an example, the presence of CO 2 leads to the formation of Li 2 CO 3 , which is more chemically stable than Li 2 O 2 and causes a larger charge overpotential, hence leading to decomposition issues of electrolytes. [5] Nevertheless, progress for the real-world usage of Li-S batteries is currently hindered by multiple drawbacks. First, despite its manifold advantages, sulfur and its discharge products (Li 2 S or Li 2 S 2 ) are inherently insulating with low conductivities of 10 −7 to 10 −30 S cm −1 at room temperature, rendering it unbefitting to be directly used as the cathode. [6] Second, the inevitable volume expansion of the electrode (≈80%) due to the contrasting densities of S 8 and Li 2 S causes structural damage during the charge/discharge cycle. [7] Third, the "polysulfide shuttle effect" would occur, whereby the soluble higher order polysulfides (Li 2 S 4 to Li 2 S 8 ) dissolve in the electrolyte and migrate between the anode and the cathode, leading to its Lithium-sulfur (Li-S) batteries have a high specific energy capacity and density of 1675 mAh g −1 and 2670 Wh kg −1 , respectively, rendering them among the most promising successors for lithium-ion batteries. However, there are myriads of obstacles in the practical application and commercialization of Li-S batteries, including the low conductivity of sulfur and its discharge products (Li 2 S/Li 2 S 2 ), volume expansion of sulfur electrode, and the polysulfide shuttle effect. Hence, immense attention has been devoted to rectifying these issues, of which the application of metal-based compounds (i.e., transition metal, metal phosphides, sulfides, oxides, carbides...

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Simulation of potential and species distribution in a Li||Bi liquid metal battery using coupled meshes

Duczek

Weber

Godinez-Brizuela

et al. 2023

Electrochimica Acta

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Current‐Induced Composition Gradients in Molten AgNO3 ‐ NaNO3: A Model System for the LiCl ‐ KCl Electrolyte of an Li/S Battery

Cited by 11 publications

References 6 publications

Modeling Potential and Species Distribution in a Li||Bi Liquid Metal Battery Using the Finite Volume Method

Modeling Potential and Species Distribution in a Li||Bi Liquid Metal Battery Using the Finite Volume Method

Lithium–Sulfur Battery Cathode Design: Tailoring Metal‐Based Nanostructures for Robust Polysulfide Adsorption and Catalytic Conversion

Simulation of potential and species distribution in a Li||Bi liquid metal battery using coupled meshes

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