Sodium Nickel Chloride Battery Research Articles

The role of sodium-nickel chloride (Na-NiCl2) batteries in managing uncertainty and renewable sources for empowering hybrid energy systems using bi-level CONOPT-based optimization

The role of sodium-nickel chloride (Na-NiCl2) batteries in managing uncertainty and renewable sources for empowering hybrid energy systems using bi-level CONOPT-based optimization

Improvement of rate capability and cycle life of Na-NiCl2 battery via designing a graphene anchoring porous nickel nanostructures as cathode

The integration of renewable energy with advanced energy storage technologies is essential. The sodium-based batteries, particularly sodium-nickel chloride (Na-NiCl2) batteries, show promise due to the abundance and low redox potential of sodium (−2.7 V vs. SHE). Despite their advantages in terms of cost, safety, and high efficiency, the improvement of rate and cycling performance of Na-NiCl2 batteries remains a challenge. To address this issue, a Ni nanostructure-supported reduced graphene oxide (RGO) composite is synthesized and combined with NaCl to serve as the cathode material for Na-NiCl2 batteries. Benefiting from the strong anchoring function of RGO, the growth of Ni is inhibited. As a result, the obtained cathode exhibits a notable specific capacity of 132.7 mAh/g at a high rate of 0.6C, along with excellent Coulombic efficiency of 100 % over 500 cycles and high energy efficiency (95.8 %). In addition, the outstanding conductivity, high specific surface area and abundant pore distribution of Ni@RGO contribute to enhanced conversion reaction and ion diffusion, and thus promoting rate capability. In contrast, the pure Ni nanosheets-based (Ni NSs) cathode is subjected to serious grain growth, which leads to poor rate performance and rapid capacity fading. By introducing conductive framework of RGO and constructing porous Ni nanostructure, the rapid electrons transport and diffusion of ions is achieved, and thus presenting the exceptional electrochemical properties.

Influence of precursor morphology and cathode processing on performance and cycle life of sodium-zinc chloride (Na-ZnCl2) battery cells

Replacing nickel by cheap and abundant zinc may enable high-temperature sodium-nickel chloride (Na-NiCl2) batteries to become an economically viable and environmentally sustainable option for large-scale energy storage for stationary applications. However, changing the active cathode metal significantly affects the cathode microstructure, the electrochemical reaction mechanisms, the stability of cell components, and the specific cell energy. In this study, we investigate the influence of cathode microstructure on energy efficiency and cycle life of sodium-zinc chloride (Na-ZnCl2) cells operated at 300 °C. We correlate the dis-/charge cycling performance of Na-ZnCl2 cells with the ternary ZnCl2-NaCl-AlCl3 phase diagram, and identify mass transport through the secondary NaAlCl4 electrolyte as an important contribution to the cell resistance. These insights enable the design of tailored cathode microstructures, which we apply to cells with cathode granules and cathode pellets at an areal capacity of 50 mAh/cm2. With cathode pellets, we demonstrate >200 cycles at C/5 (10 mA/cm2), transferring a total capacity of 9 Ah/cm2 at >83% energy efficiency. We identify coarsening of zinc particles in the cathode microstructure as a major cause of performance degradation in terms of a reduction in energy efficiency. Our results set a basis to further enhance Na-ZnCl2 cells, e.g., by the use of suitable additives or structural elements to stabilize the cathode microstructure.

Development and Characterization of New Cathode Materials for Sodium-Metal Chloride Batteries

Solid metal halides are used as active cathode ingredients in the case of Na-NiCl2 batteries that require a fused secondary electrolyte, sodium tetrachloraluminate (NaAlCl4), to facilitate the movement of the Na+ ion into the cathode. The sodium-nickel chloride (Na - NiCl2) battery has been extensively investigated as a promising system for large-scale energy storage applications. The growth of Ni and NaCl particles in the cathodes is one of the most important factors that degrade the performance of the Na-NiCl2 battery. The larger the particles of active ingredients contained in the cathode, the smaller the active surface available for the electrochemical reaction. Therefore, the growth of Ni and NaCl particles can lead to an increase in cell polarization resulting from the reduced active area. A higher current density, a higher state of charge (SOC) at the end of the charge (EOC) and a lower Ni / NaCl ratio are the main parameters that result in the rapid growth of Ni particles.In light of these problems, cathode and chemistry Nano-materials with recognized and well-documented electrochemical functions have been studied and manufactured to simultaneously improve battery performance and develop less expensive and more performing, sustainable and environmentally friendly materials. Starting from the well-known cathodic material (Na-NiCl2), the new electrolytic materials have been prepared on the replacement of nickel with iron (10-90%substitution of Nichel with Iron), to obtain a new material with potential advantages compared to current battery technologies; for example, (1) lower cost of cathode material compared to the state of the art as well as (2) choices of cheaper materials (stainless steels could be used for cell components, including cathode current collectors and cell housings).The study on the particle size of the cathode and the physico-chemical characterization of the cathode was carried out in the test cell using, where possible, the GITT method (galvanostatic technique of intermittent titration). Furthermore, the impact of temperature on the different cathode compositions of the positive electrode was being studied. Especially the optimum operating temperature is an important parameter of the active material.

(Invited) Low-Temperature Molten Sodium Batteries for Large-Scale Storage: Fundamental Studies of Metal Halide Catholyte and Cathode Materials

Low-cost, long-duration energy storage is a vital resource needed for a robust electric grid powered by renewables. Low-temperature (<130 °C) molten sodium batteries (MNaBs) with NaI-metal halide molten salt catholytes have been developed to meet this need. This battery chemistry avoids the safety concerns caused by metal dendrites and flammable organic solvents found in Li-metal or Li-ion batteries. It also offers higher voltages and drastically reduces the expensive high temperature material requirements compared to other MNaBs, such as sodium-nickel chloride (ZEBRA) batteries, which operate near 300 °C. Among the key challenges to wide-spread utilization of these emerging molten Na batteries for large-scale, long-duration applications is catholyte stability and performance at high current densities while cycling at temperatures just above the melting point of Na (98 °C). To optimize the catholyte, we have examined a variety of electroactive molten salt chemistries, including mixtures of NaI with AlCl3, AlBr3, and GaCl3. To better understand the catholyte properties during cycling, we have performed electrochemical kinetics studies and mathematical modeling of the iodide-triiodide speciation. Results reveal a dependence between catholyte speciation and usable capacity and current densities for the given catholyte compositions. Additional experiments, including cyclic voltammetry and chronoamperometry, probe the interactions between the cathode current collector and the molten salts, revealing potential impacts on electrochemical kinetics and stability during cycling. Insights from these fundamental studies serve as the foundation for the informed design of high-performance cathodes in new scalable molten sodium batteries.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Study of Three-Component System Al, Na, Li/Cl for Sodium Nickel-Chloride Batteries

The electrical conductivity, thermochemical and electrochemical properties of a system consisting of melts of aluminium trichloride and sodium-lithium chlorides taken in different ratios have been studied. In this system, the electrochemical behaviour of Ni2+ ions via cyclic voltammetry and the electromotive force in the modes of heating and cooling of the system were studied. It was found that the melting temperature of the melts passes through a minimum at a lithium chloride (хLiCl) content from 0.23 to 0.35. A possibility of reducing the starting temperature of a nickel-chloride battery with a partial replacement of sodium chloride with lithium chloride is shown, as well as stabilization of its operation at a minimum temperature of 240 °C. An admissibility of using the optimal compositions of the system as an electrolyte in sodium nickel-chloride batteries has been established. It was found that the composition 0.5AlCl3-0.23LiCl-0.27NaCl has a minimum melting point (111 °C), a minimum activation energy for conductivity (8.9 kJ∙mol-1), and a sufficiently high electrical conductivity (0.53 S∙cm-1 at 250 °C).

Application of Neural Networks in a Sodium-Nickel Chloride Battery Management System

Application of Neural Networks in a Sodium-Nickel Chloride Battery Management System

Multicriteria Evaluation of Portable Energy Storage Technologies for Electric Vehicles

The conventional vehicles are a major cause of the greenhouse gases emissions in the global environment. Electric vehicles are a sustainable alternative to the conventional vehicles due to the negligible emissions and the possibility of the renewable energy integration. However, the electric vehicles require the separate storage systems and the selection of the proper storage system is a major concern in the electric vehicles markets. The storage system should be selected in a systematic and rational way. Hence, this paper evaluates the existing storage technologies for electric vehicles based on a multi-criteria decision making model. For this purpose, this paper performs a comprehensive literature review of the existing storage technologies for electric vehicles. Then, this paper evaluates the key storage technologies for electric vehicles based on the five criteria including cost, technical features, compatibility, technological maturity, and environment, health, and safety. These criteria and their sub-criteria were used in the development of an analytic hierarchy process (AHP) model. The proposed AHP model was solved using Super Decisions software. Results offer the various insights for the selection of a proper storage system for electric vehicles. In most of the cases, AHP model suggested the utilization of hybrid sodium-nickel chloride battery (SNCB) and supercapacitors (SC) for electric vehicles. Besides, the higher capital cost has been identified as the key barrier in the adoption several storage technologies such as lithium ion battery (LIB) and hydrogen fuel cells (HFC) storage.

Understanding the influencing factors of porous cathode contributions to the impedance of a sodium-nickel chloride (ZEBRA) battery

Molten-sodium beta-alumina batteries including sodium–sulfur (NAS) and sodium-metal chloride (ZEBRA) batteries have been considered as promising candidates for reliable low-cost stationary energy storage devices. The structural parameters of the porous cathode wetted by NaAlCl4 have been proved to be one of the important reasons for the degradation of ZEBRA batteries. Herein, the influencing factors of porous cathode on the impedance of Na–NiCl2 battery are investigated in detail. The interface between the NaAlCl4 catholyte and Ni/NaCl cathode material and the ratio of the conductive components in the cathode are discussed in this paper. Based on the wettability results of each component of the cathode material at different porosities and temperatures, the wetting behavior between NaAlCl4 and the porous cathode is summarized. Both the porosity and metal ratio of the cathode need to be considered in order to achieve the optimal catholyte/cathode material interface and minimum operating impedance. The proposed cathode parameters are porosity greater than 24% and conductive component ratio of 1.5 at NaAlCl4 ratio of 1.75. This work provides a quantitative guidance and deep understanding for the material design of ZEBRA battery cathodes.

The Renaissance of Liquid Metal Batteries

Next-generation batteries with long life, high-energy capacity, and high round-trip energy efficiency are essential for future smart grid operation. Recently, Cui et al. demonstrated a battery design meeting all these requirements—a solid electrolyte-based liquid lithium-brass/zinc chloride (SELL-brass/ZnCl2) battery. Such a battery design overcomes some inherent problems of conventional ZEBRA batteries and lithium ion batteries.

Constructing a charged-state Na-NiCl2 battery with NiCl2/graphene aerogel composite as cathode

The charged-state NiCl 2 -rGO aerogel cathode shows superior cycle performance in Na-NiCl 2 batteries. • Charged-state NiCl 2 -rGO aerogels are prepared by freeze-drying methods. • Conductive rGO aerogels effectively improve the performance of NiCl 2 . • The molar ratio of Ni/NaCl can be reduced to the stoichiometric ratio (0.5). • The NiCl 2 -rGO aerogel cathode shows excellent electrochemical performance. The hierarchical nickel chloride/reduced graphene oxide (NiCl 2 -rGO) aerogels are synthesized via a facile hydrothermal and freeze-drying methods using low-cost nickel chloride hexahydrate (NiCl 2 ·6H 2 O) as raw material. The NiCl 2 -rGO hybrid aerogel structure enables the uniform distribution of lamellar NiCl 2 on the three-dimensional (3D) cross-linked conductive graphene sheets. When employed as cathode for sodium-nickel chloride (Na-NiCl 2 ) batteries, the as-obtained NiCl 2 -rGO aerogels exhibit excellent electrochemical performance with high reversible capacities (116 mAh g −1 after 50 cycles, 128 mAh g −1 in a fixed capacity window (20%–80% state of charge (SOC)) after 50 cycles), and a ultra-low polarization (0.05 V in the fixed capacity window). The outstanding performance of NiCl 2 -rGO aerogels can be attributed to the excellent conductivity of graphene. Moreover, the strong contact between NiCl 2 and graphene sheets can effectively promote the transfer of electrons. Compared with traditional tubular Na-NiCl 2 batteries, the molar ratio of Ni/NaCl of NiCl 2 -rGO aerogels can be decreased from 1.8 to the stoichiometric ratio (0.5). To the best of our knowledge, this work paves a perspective way for the first time to develop charged-state NiCl 2 -based cathodes with splendid performance for Na-NiCl 2 batteries.

(Invited) Stress Evolution on the Solid Electrolyte in Lower Temperature Operating Planar Sodium Nickel Chloride Batteries

Sodium nickel chloride (Na-NiCl2) battery is one of the most promising candidates as a large scale electrochemical energy storage device since it offers high safety, long lifetime, and high energy density. The battery comprises molten metallic Na and NiCl2 as negative and positive electrodes, respectively, separating them by a β”-Al2O3–family solid electrolyte (BASE). In order to facilitate fast sodium-ion transport in the cathode compartment, the battery typically operates at 300oC accompanying with molten NaAlCl4 (catholyte), which is infiltrated into the cathode materials powder. A drawback of the efficient battery hampering broader market penetration is high manufacturing cost as it adopts expensive heterogeneous sealing technologies, such as thermal compression bonding, glass sealing, and laser beam welding, which are inevitable to withstand its high operating temperature. However, when lowering the operating temperature down to below 200oC, inexpensive polymer can be introduced replacing all the expensive sealing technologies, through which cell manufacturing process can be substantially simplified at the same time.In developing the lower temperature operating planar Na-NiCl2 battery, one of the major cell failure modes is mechanical failure in solid electrolytes either by thermal stress accumulation upon freeze-thaw cycles or by stresses developed by pressure difference between cathode and anode compartments during charge-discharge cycles. The presentation will start with defining failure modes of this new class of Na beta-alumina battery with special emphasis on electrolyte failure. In order to understand the stress accumulation in the vicinity of the solid electrolyte, a set of finite element analyses (FEA) has been conducted for various simulated conditions. It turns out that (1) sealing temperature, and (2) inner volumes of cathode and anode compartments need to be carefully designed to avoid the mechanical failure. The results of the calculation and cell design strategy for this novel battery will be discussed. Figure 1

(Invited) Advanced Intermediate Temperature Na-Metal Halide Batteries for Grid Applications

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Recently, the research of Na-MH battery has been focusing on the development of battery technologies operated at intermediate temperature (< 200oC), which has several advantages including simple cell architectures, improved thermal management, lower operating temperature, and lower manufacturing cost over high temperature Na based batteries. Here, we will introduce the mechanism of battery degradation, the development of advanced low-cost cathode materials, long-term cycle results, and the current status and prospects of scale up this promising battery technology.

(Invited) Low-Cost and High Rate Na-FeCl2 Batteries for Large Scale Energy Storage Applications

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Considering constraints of the Ni-based cell chemistry, it is highly desirable to develop an alternate cathode for Na-MH batteries towards next-generation energy storage applications. This pursuit, unsurprisingly, led us to the Fe/NaCl cathode. In this study, we present an advanced Na-FeCl2 battery with unprecedented high-rate performance and low cost for stationary energy storage applications. Operated at an extremely high current density of 33.3 mA/cm2 at 190°C, the cell can output 74% of its total capacity—a capacity retention double that of IT Na-NiCl2 cells. The origin of the high rate capability of Na-FeCl2 batteries was elucidated by means of comprehensive phase/structure analysis and electrochemical/electroanalytical characterizations. Moreover, Fe particle pulverization originating from liquid-phase reactions was determined to be the major source of capacity fading during long-term cycling. Accordingly, we designed a unique cathode with Ni additive, which delivered a high discharge specific energy density of over 295 Wh/kg for 200 cycles at C/5 with almost no capacity fading.

Molten Lithium-Brass/Zinc Chloride System as High-Performance and Low-Cost Battery

Summary Batteries with high safety, low cost, and reasonable energy density are essential for grid-scale energy storage and still remain elusive. Here, we report a solid electrolyte-based liquid lithium-brass/zinc chloride (SELL-brass/ZnCl2) battery using garnet-type lithium-ion solid electrolyte, lithium anode, and brass/ZnCl2 cathode. The chemistry of the cell reaction and the ability of being assembled in discharged state ensures a high safety. The use of low-cost ZnCl2 cathode can realize a low cell material cost of $16 kWh−1. The adoption of lithium anode guarantees a high theoretical energy density of 750 Wh kg−1 and 2,250 Wh L−1. Moreover, by using brass powder as a Zn source in the cathode, the Zn particle growth issue is successfully solved, and a good cycling stability of the battery can be obtained. As full cell performance and scalability are also verified, our SELL-brass/ZnCl2 battery shows a high potential for practical use in grid energy storage.

Experimental Investigation of an Electrical Model for Sodium–Nickel Chloride Batteries

This work describes the experimental characterization of a commercial sodium–nickel chloride battery and the investigation on a state-of-the-art model that represents the battery behavior. This battery technology is considered very promising but it has not fully been exploited yet. Besides improvements on the technological side, accurate models of the battery should be found to allow the realization of Battery Management Systems with advanced functions. This achievement may extend the battery exploitation to its best. The paper describes the experimental set-up and the model parameter identification process, and discusses the identified parameters and the model validation tests. The comparison between model simulations and experiments shows that the model is rather accurate for low-current rates, but it loses accuracy and it is not able to reproduce with fidelity the battery behavior at low states of charge or at high current rates. Further research efforts and refinements of the model are necessary to make available a sodium–nickel chloride battery model accurate in any operating condition.

Pressure management and cell design in solid-electrolyte batteries, at the example of a sodium-nickel chloride battery

Solid electrolytes in combination with alkali-metal anodes offer the potential to enhance battery energy density and safety. The inherent challenges associated with cell pressure management have to be accounted for in the cell design but are not sufficiently understood. Here we present a theoretical study linking the effects of thermal and chemo-mechanical expansion of electrode materials to the stresses acting on tubular and planar solid electrolytes, at the example of the sodium-nickel chloride battery chemistry. Based on our analysis, we derive three strategies to reduce these stresses. Namely, we propose (i) to increase the cell closing temperature during production (ii) to reduce the gas pressure in the cell (e.g. by applying a vacuum), and (iii) to rationally balance the volume of the two electrode compartments. Mechanical considerations developed herein form the foundation for the development of next-generation battery cell designs.

Low-Cost and High Rate Na-FeCl2 Batteries for Large Scale Energy Storage Applications

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Considering constraints of the Ni-based cell chemistry, it is highly desirable to develop an alternate cathode for Na-MH batteries towards next-generation energy storage applications. This pursuit, unsurprisingly, led us to the Fe/NaCl cathode. In this study, we present an advanced Na-FeCl2 battery with unprecedented high-rate performance and low cost for stationary energy storage applications. Operated at an extremely high current density of 33.3 mA/cm2 at 190°C, the cell can output 74% of its total capacity—a capacity retention double that of IT Na-NiCl2 cells. The origin of the high rate capability of Na-FeCl2 batteries was elucidated by means of comprehensive phase/structure analysis and electrochemical/electroanalytical characterizations. Moreover, Fe particle pulverization originating from liquid-phase reactions was determined to be the major source of capacity fading during long-term cycling. Accordingly, we designed a unique cathode with Ni additive, which delivered a high discharge specific energy density of over 295 Wh/kg for 200 cycles at C/5 with almost no capacity fading.

Ni-less cathode with 3D free-standing conductive network for planar Na-NiCl2 batteries

The sodium-nickel chloride (Na-NiCl2) batteries technology has been considered as one of the most promising candidates for large-scale electrical energy storage application owing to its abundant electrode material resource, high energy density and safety. However, ultra-excessive Ni in the cathode leads to high material cost and the growth of cathode particles during cycles makes degradation of batteries performances, which hinder the further application of Na-NiCl2 batteries. To address these challenges, we designed a free-standing Ni-less cathode with Ni/NaCl particles uniformly distributed in the three-dimensional (3D) conductive matrix constructed by carbonfiber (CF) and multiwalled carbon nanotubes (MWCNTs). The 3D hierarchical structure synthesized by low-cost vacuum filtration method can offer sufficient void space to accommodate the growth of NaCl particles and effectively enhance the electronic conductivity of the cathode. When the molar ratio of Ni/NaCl in the cathode is reduced to 1.0, a specific capacity of 90 mAh g−1 for planar Na-NiCl2 batteries can be achieved after 170 cycles at 190 °C with a capacity retention of 67%, which is higher than that of traditional tubular Na-NiCl2 batteries.

Tailoring Materials Chemistry to Advance Low Temperature Molten Sodium Batteries

The global implementation of secondary lithium ion (Li-ion) batteries continues to expand rapidly, finding clear utility in portable electronics and vehicle electrification. For large format, grid-scale energy storage however, concerns over the safety, reliability, cost, and lifetime of these batteries has motivated the drive to find alternatives to Li-ion systems. Here we describe the materials-driven development of a low temperature molten sodium-halide battery for grid-scale applications. Molten sodium batteries, such as sodium sulfur (NaS) and sodium nickel chloride (Na-NiCl2or ZEBRA) batteries, continue to show promise for grid-scale applications, valued for their use of earth abundant chemistries, scalability, and the absence of volatile, potentially hazardous organic electrolytes. Widespread implementation of these batteries has been limited, however, by relatively high operating temperatures (~300°C). Potentially impacting both cost and lifetime of these batteries, lowering the battery operating temperature would reduce material degradation, enable the use of lower cost battery components, and facilitate simplified, more cost effective heat management and operating strategies. The promising low temperature system described here comprises a molten sodium anode, a solid state ion-conducting separator, and a sodium iodide (NaI)-based molten salt catholyte. This NaI-based system avoids the hazards of volatile organic electrolytes, employing a fully molten catholyte designed to enable long cycle life while still offering a higher voltage (>3V) than traditional molten sodium batteries. Here, we will describe promising demonstrations of prototype battery cycling at drastically reduced operating temperatures near 100°C. In addition, we will address new materials challenges unique to operating a molten sodium battery at these reduced temperatures. In particular, we will focus on the complex goal of increasing lower temperature separator conductance in mechanically robust solid state electrolytes while minimizing resistances at interfaces between these separators and the molten anode and catholyte. Tuning separator materials chemistry and microstructure, both in the bulk and at separator interfaces, can significantly impact electrolyte wetting, reduce cell resistance, and improve battery cycling performance. Continued development of these emerging molten Na-NaI batteries promises a new route to the type of safe, cost-effective, long-lifetime batteries needed for grid-scale energy storage. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.