Low-Temperature Molten Salt Electrolytes for Membrane-Free Sodium Metal Batteries

Spatocco, Brian L.; Ouchi, Takanari; Lambotte, Guillaume; Burke, Paul; Sadoway, Donald R.

doi:10.1149/2.0441514jes

Cited by 36 publications

(21 citation statements)

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“…During recent years, a unique binary electrolyte consisting of NaOH and NaI (molar ratio of ca. 0.8 to 0.2) has been developed, which shows a low eutectic melting temperature of 220 o C. 331 Another characteristic of the molten salt electrolyte, which should be considered, is the decomposition voltage. A high decomposition voltage is desired as it could render high charging and discharging voltages.…”

Section: Liquid Metal Batteriesmentioning

confidence: 99%

Electrolytes for electrochemical energy storage

Xia

et al. 2017

Mater. Chem. Front.

225

116

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk Journal NameThis journal is © The Royal Society of Chemistry 20xxJ. Name., 2013, 00, 1-3 | 1 Electrolyte is a key component of electrochemical energy storage (EES) devices and its properties greatly affect the energy capacity, rate performance, cyclability and safety of all EES devices. This article offers a critical review of recent progresses and challenges in electrolyte research and development particularly for supercapacitors and supercapatteries, recharegable batteries (such as lithium-ion and sodium-ion batteries), and redox flow batteries (including fuel cells in a broad sense). The review will focus on liquid electrolytes, particularly aqueous and organic electrolytes, ionic liquids and molten salts. Influences of electrolyte properties on the performances of different EES devices are discussed in detail.

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Section: Liquid Metal Batteriesmentioning

confidence: 99%

Electrolytes for electrochemical energy storage

Xia

et al. 2017

Mater. Chem. Front.

225

116

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“…The differential density cells employed for the initial MIT investigations gave later way to cells that used metal foam immersed in the electrolyte to contain the negative electrode [15,13,79,19,94].…”

Section: Lmbs For Stationary Storagementioning

confidence: 99%

Fluid Mechanics of Liquid Metal Batteries

Kelley

Weier

2018

Applied Mechanics Reviews

101

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The design and performance of liquid metal batteries, a new technology for grid-scale energy storage, depend on fluid mechanics because the battery electrodes and electrolytes are entirely liquid. Here we review prior and current research on the fluid mechanics of liquid metal batteries, pointing out opportunities for future studies. Because the technology in its present form is just a few years old, only a small number of publications have so far considered liquid metal batteries specifically. We hope to encourage collaboration and conversation by referencing as many of those publications as possible here. Much can also be learned by linking to extensive prior literature considering phenomena observed or expected in liquid metal batteries, including thermal convection, magnetoconvection, Marangoni flow, interface instabilities, the Tayler instability, and electro-vortex flow. We focus on phenomena, materials, length scales, and current densities relevant to the liquid metal battery designs currently being commercialized. We try to point out breakthroughs that could lead to design improvements or make new mechanisms important.The story of fluid mechanics research in liquid metal batteries (LMBs) begins with one very important application: grid-scale storage. Electrical grids have almost no energy storage capacity, and adding storage will make them more robust and more resilient even as they incorporate increasing amounts of intermittent and unpredictable wind and solar generation. Liquid metal batteries have unique advantages as a grid-scale storage technology, but their uniqueness also means that designers must consider chemical and physical mechanisms -including fluid mechanisms -that are relevant to few other battery technologies, and in many cases not yet well-understood. We will review the fluid mechanics of liquid metal batteries, focusing on studies undertaken with that technology in mind, and also drawing extensively from prior work considering similar mechanisms in other contexts. In the interest of promoting dialogue across this new field, we have endeavored to include the work of many different researchers, though inevitably some will have eluded our search, and we ask for the reader's sympathy for regrettable omissions. Our story will be guided by technological application, focusing on mechanisms most relevant to liquid metal batteries as built for grid-scale storage. We will consider electrochemistry and theoretical fluid mechanics only briefly because excellent reviews of both topics are already available in the literature. In §1 below we provide an overview and brief introduction to liquid metal batteries, motivated by the present state of worldwide electrical grids, including the various types of liquid metal batteries that have been developed. We consider the history of liquid metal batteries in more detail in §2, connecting to the thermally regenerative electrochemical cells developed in the middle of the twentieth century. Continuing, we consider the fluid mechanisms that are most relevant to ...

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“…[4][5][6] The thought was that electrolysis at a lower temperature would reduce operating costs and improve process efficiency. More recently, in connection with work on sodium-based liquid metal batteries, Spatocco et al 7 investigated a binary eutectic of NaOH and NaI as an electrolyte operable at intermediate temperature (<280…”

mentioning

confidence: 99%

Communication—Molten Amide-Hydroxide-Iodide Electrolyte for a Low-Temperature Sodium-Based Liquid Metal Battery

Ashour

Yin

Ouchi

et al. 2017

J. Electrochem. Soc.

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The low cost and high abundance of sodium make it an attractive choice for the negative electrode in a liquid metal battery. However, sodium has not found use in this application owing to the high solubility of the metal in its molten halides which results in poor coulombic efficiency and an unacceptably high rate of self discharge. In this work, we investigated the electrochemical behavior of the ternary eutectic of NaNH 2 , NaOH and NaI (m.p. 127 • C) and evaluated its usefulness as an electrolyte for sodium-based liquid metal batteries. Cyclic voltammetry revealed an electrochemical window of 1.3 V at 180 • C. The anodic limit is set by the oxidation of amide anions to form hydrazine gas. Liquid metal batteries consist of two metals of different electronegativity separated by molten salt. During discharge, the battery operates through alloying an electropositive liquid metal (e.g. Mg, Na, Li, or Ca) in an electronegative metal (e.g. Bi, Pb, Sb, or Zn). The all-liquid design allows the battery to operate at high current densities (1 A/cm 2 ) 1 with low overvoltage due to fast mass transport in the liquid state and high ionic conductivity of molten salts. Moreover, the absence of solid electrodes endows the battery with an extended service lifetime (>10,000 cycles). 2,3The negative and positive electrodes are selected based on melting point and density as well as the voltage associated with alloy formation, whereas the electrolyte is chosen based on melting point, metal solubility, density, ionic conductivity, and electrochemical window. 2Metal solubility in the electrolyte varies exponentially with operating temperature. High metal solubility in the electrolyte can influence the performance of liquid metal battery through increasing electronic conductivity, which increases the rate of self-discharge leading to lower coulombic efficiency. A low-melting electrolyte (<200• C) can substantially reduce metal solubility thereby allowing batteries to be built with low-cost negative electrodes (e.g., Na, Ca) that are otherwise inaccessible at higher temperatures (>500• C). Moreover, reducing the operating temperature below 200• C can also reduce the total battery cost through savings associated with cell container, thermal insulation, and wiring.Early work on low-melting sodium-bearing salts focused on mixtures of NaOH, NaI, and NaBr and was driven by their utility for sodium electrowinning. [4][5][6] The thought was that electrolysis at a lower temperature would reduce operating costs and improve process efficiency. More recently, in connection with work on sodium-based liquid metal batteries, Spatocco et al.7 investigated a binary eutectic of NaOH and NaI as an electrolyte operable at intermediate temperature (<280• C). An electrochemical window of 2.4 volts was measured at 250• C. In contact with liquid sodium, significantly lower values of self-discharge current were observed in this melt compared to those in early Na||Bi cells operating at much higher temperatures (necessitated by their higher-melting halide elec...

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Low-Temperature Molten Salt Electrolytes for Membrane-Free Sodium Metal Batteries

Cited by 36 publications

References 36 publications

Electrolytes for electrochemical energy storage

Electrolytes for electrochemical energy storage

Fluid Mechanics of Liquid Metal Batteries

Communication—Molten Amide-Hydroxide-Iodide Electrolyte for a Low-Temperature Sodium-Based Liquid Metal Battery

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