SEARCH · Search NASA

Results for “Cathodic corrosion”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12

All sources NASA NTRS DOE OSTI

NASA NTRS1974

Stress corrosion cracking of a titanium alloy in chloride-containing liquid environments

Ti-8 Al-1 Mo-1 V was tested in solvents containing chloride, bromide or iodide ions. It was found that the region II plateau velocity could be correlated with the inverse of the viscosity for several solvents. It seems most likely that this reflects the influence of the viscosity on the diffusion coefficient of some species involved in a mass transfer process which limits the crack growth. Associated tests were performed in which the potential, pH and concentration of Cl- were varied, in some of the same solutions as used for the viscosity tests. It is concluded from these tests that the absence of cathodic protection against cracking in solutions of low pH arises from an ohmic effect which isolates the crack tip from external potential control.

Smyrl, W. H.↗

DOE OSTI2024

Chloride-Induced Stress Corrosion Cracking of Friction Stir-Welded 304L Stainless Steel: Effect of Microstructure and Temperature

Dry storage canisters of used nuclear fuels are fabricated using SUS 304L stainless steel. Chloride-induced stress corrosion cracking (CISCC) is one of the major failure modes of dry storage canisters. The cracked canisters can be repaired by friction stir welding (FSW), a low-heat input ‘solid-phase’ welding process. It is important to evaluate the ClSCC resistance of the friction stir welded material. Stress corrosion cracking (SCC) studies were carried out on mill-annealed base materials and friction stir welded 304L stainless U-bend specimens in 3.5% NaCl + 5 N H2SO4 solution at room temperature and boiling MgCl2 solution at 155 °C. The engineering stress on the outer fiber of the FSW U-bend specimen was ~60% higher than that of the base metal (BM). In spite of the higher stress level of the FSW, both materials (FSW and BM) showed almost similar SCC failure times in the two different test solutions. The SCC occurred in the thermo-mechanically affected zone (TMAZ) of the FSW specimens in the 3.5% NaCl + 5 N H2SO4 solution at room temperature, while the stirred zone (SZ) was relatively crack-free. The failure occurred at the stirred zone when tested in the boiling MgCl2 solution. Hydrogen reduction was the cathodic reaction in the boiling MgCl2 solution, which promoted hydrogen-assisted cracking of the heavily deformed stirred zone. The emergence of the slip step followed by passive film rupture and dissolution of the slip step could be the SCC events in the 3.5% NaCl + 5 N H2SO4 solution at room temperature. However, the slip step height was not sufficient to cause passivity breakdown in the fine-grained SZ. Therefore, the SCC occurred in the partially recrystallized softer TMAZ. Overall, the friction-stirred 304L showed higher tolerance to ClSCC than the 304L base metal.

304L austenitic stainless steel↗

DOE OSTI2022

Highly reversible Zn metal anode enabled by sustainable hydroxyl chemistry

Rechargeable Zn metal batteries (RZMBs) may provide a more sustainable and lower-cost alternative to established battery technologies in meeting energy storage applications of the future. However, the most promising electrolytes for RZMBs are generally aqueous and require high concentrations of salt(s) to bring efficiencies toward commercially viable levels and mitigate water-originated parasitic reactions including hydrogen evolution and corrosion. Electrolytes based on nonaqueous solvents are promising for avoiding these issues, although full cell performance demonstrations with solvents other than water have been very limited. To address these challenges, we investigated MeOH as an alternative electrolyte solvent. These MeOH-based electrolytes exhibited exceptional Zn reversibility over a wide temperature range, with a Coulombic efficiency > 99.5% at 50% Zn utilization without cell short-circuit behavior for > 1,800 h. More important, this remarkable performance translates well to Zn || metal-free organic cathode full cells, supporting < 6% capacity decay after > 800 cycles at –40°C.

25 ENERGY STORAGE↗

DOE OSTI2023

The evolution of pit morphology and growth kinetics in aluminum during atmospheric corrosion

Abstract Assessing the lifetimes of alloys in humid, corrosive environments requires growth kinetic information regarding individual instances of damage, e.g. pit growth rates. Corrosion rates measured at the continuum scale using mass change convolute the rate of pit nucleation and growth, providing limited information on local kinetics. The current study used in-situ X-ray computed tomography to measure growth rates of individual pits in aluminum over 100 h of exposure in a humid, chloride environment. While pits grew at relatively constant rates over the first hours after nucleation, significant growth-rate nonlinearities subsequently occurred. These were linked to both droplet spreading, which altered the cathode size, and changes in the mode of pit growth. Pit morphology appeared to influence the dominant growth mode and the duration of pit growth. Post-mortem serial sectioning revealed pits preferentially attacked grain-boundary triple junctions and dislocation boundaries.

Noell, Philip J. (ORCID:0000000346998999)↗

DOE OSTI2024

Fast Oxygen Redox Kinetics Induced by CoO 6 Octahedron With π –Interaction in P2–Type Sodium Oxides

Enhancing the kinetics of lattice oxygen redox (LOR) in P2-type layered sodium oxide cathodes is crucial for the advancement of sodium-ion batteries (SIBs) with superior energy and power densities. Electronic structure regulation stands out as a highly effective approach to address the inherent limitations of P2-type layered oxides with LOR, including sluggish kinetics, phase transitions, voltage hysteresis, and local structural distortion. In this work, a strategy involving the introduction of CoO 6 octahedra with π-interaction into Na 0.6 Li 0.1 Fe 0.3–x Co x Mn 0.6 O 2 (x = 0, 0.15, 0.3) cathodes to facilitate Na-ion transport is proposed. Furthermore, the impact of FeO 6 octahedra with σ-interaction in P2-type cathodes on electrochemical performance is comprehensively investigated. Through multimodal in-situ and ex-situ characterization techniques, it is revealed that Co–O with π-interaction effectively mitigates P2-OP4 phase transitions by strengthening Na–O, reduces voltage hysteresis, and stabilizes the local structure. Consequently, Na 0.6 Li 0.1 Co 0.3 Mn 0.6 O 2 demonstrates enhanced Na-ion diffusion kinetics, leading to improved rate performance and a reversible capacity of 55 mAh g –1 at 10 C, significantly outperforming cathodes with Fe–O σ-interaction. Moreover, when coupled with hard carbon, the full cell achieves a remarkable energy density of 395 Wh kg –1 (on cathode) at 0.1 C, with a capacity retention of 75% over 100 cycles at 1 C.

25 ENERGY STORAGE↗

DOE OSTI2021

Understanding the Stability of Etched or Platinized p-GaInP Photocathodes for Solar-Driven H 2 Evolution

The long-term stability in acidic or alkaline aqueous electrolytes of p-Ga 0.52 In 0.48 P photocathodes, with a band gap of ~1.8 eV, for the solar-driven hydrogen-evolution reaction (HER) has been evaluated from a thermodynamic, kinetic, and mechanistic perspective. At either pH 0 or pH 14, etched p-GaInP electrodes corroded cathodically under illumination and formed metallic In 0 on the photoelectrode surface. In contrast, under the same conditions, electrodeposition of Pt facilitated the HER kinetics and stabilized p-GaInP/Pt photoelectrodes against such cathodic decomposition. When held at 0 V versus the reversible hydrogen electrode, p-GaInP/Pt electrodes in either pH = 0 or pH = 14 exhibited stable current densities (J) of ~-9 mA cm -2 for hundreds of hours under simulated 1 sun illumination. During the stability tests, the current density-potential (J-E) characteristics of the p-GaInP/Pt photoelectrodes degraded due to pH-dependent changes in the surface chemistry of the photocathode. This work provides a fundamental understanding of the stability and corrosion mechanisms of p-GaInP photocathodes that constitute a promising top light absorber for tandem solar-fuel generators.

14 SOLAR ENERGY↗

DOE OSTI2022

Tuning the Solvation Structure in Aqueous Zinc Batteries to Maximize Zn-Ion Intercalation and Optimize Dendrite-Free Zinc Plating

Aqueous zinc batteries are recognized to suffer from H + /Zn 2+ coinsertion in the cathode, but few approaches have been reported to suppress deleterious H + intercalation. We realize this goal by tuning the solvation structure, using LiV 2 (PO 4 ) 3 (LVP) as a model cathode. Phase conversion of LVP induced by H + intercalation is observed in 4 m Zn(OTf) 2 , whereas dominant Zn 2+ insertion is confirmed in a ZnCl 2 water-in-salt electrolyte (WiSE). This disparity is ascribed to the complete absence of free water and a strong Zn 2+ –H 2 O interaction in the latter that interrupts the H 2 O hydrogen bonding network, thus suppressing H + intercalation. On the basis of this strategy, a novel PEG-based hybrid electrolyte is designed to replace the corrosive ZnCl2 WiSE. This system exhibits an optimized Zn 2+ solvation sheath with a similar low free water content, showing not only much better suppression of H + intercalation but also highly reversible Zn plating/stripping with a CE of ~99.7% over 150 cycles.

25 ENERGY STORAGE↗

DOE OSTI2022

Prospective Life Cycle Assessment of Synthetic Graphite Manufactured via Electrochemical Graphitization

Lithium-ion batteries (LIBs) are expected to play a crucial role in meeting many of the clean energy-related goals. Due to its electrical properties such as good conductance, chemical inertness, and corrosion resistance, graphite is a very popular anode for LIBs. Traditional methods of producing battery-grade graphite (high purity >99%) include processing naturally mined graphite or manufacturing synthetic graphite via the Acheson process, which converts soft amorphous carbons such as petroleum coke into graphite by subjecting it to high temperature (up to 3000 °C) for prolonged periods of times (3–5 days). However, due to a lack of abundant high purity natural graphite sources, synthetic graphite is the preferred choice for many LIBs. A new synthetic electrochemical graphitization method that subjects the amorphous carbon precursor submerged in a molten salt mixture to a constant cathodic polarization (against a graphitic anode) has been discovered that has significantly lower graphitization temperatures (~800 °C) and reduced graphitization time (3–6 h). Furthermore, the method can accept a higher variety of carbon precursors compared to the Acheson process. A prospective life cycle assessment (LCA) is conducted on this new method and compared against the traditional processes. The laboratory-scale demonstration of the method is used to build an inventory, which through various assumptions is scaled up to a commercial scale. An additional scenario is also considered with a biomass-derived carbon precursor for the graphite. The results from the LCA show that while the laboratory scale process is similar to the Acheson process and natural flake graphite in terms of impact, the scaled-up process is drastically better than the Acheson process in all environmental categories. Using a coconut shell-derived biomass precursor has a higher impact due to its manufacturing in Indonesia, as the Indonesian energy grid is highly fossil fuel dependent. Therefore, the biomass carbon may have a higher impact than petroleum coke dependent on the location of production of biomass-derived carbon black. The LCA has identified the molten salt—CaCl 2 —as a potential hotspot and suggests other salts should be considered. Accordingly, the new method shows promise in this early stage LCA in improving the environmental performance of graphite (and by relation LIBs) and therefore needs to be explored more in terms of its commercial viability.

25 ENERGY STORAGE↗

DOE OSTI2020

Single Cobalt Sites Dispersed in Hierarchically Porous Nanofiber Networks for Durable and High-Power PGM-Free Cathodes in Fuel Cells

Increasing catalytic activity and durability of atomically dispersed metal–nitrogen–carbon (M–N–C) catalysts for the oxygen reduction reaction (ORR) cathode in proton-exchange-membrane fuel cells remains a grand challenge. In this study, a high-power and durable Co–N–C nanofiber catalyst synthesized through electrospinning cobalt-doped zeolitic imidazolate frameworks into selected polyacrylonitrile and poly(vinylpyrrolidone) polymers is reported. The distinct porous fibrous morphology and hierarchical structures play a vital role in boosting electrode performance by exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transport of reactant. The enhanced intrinsic activity is attributed to the extra graphitic N dopants surrounding the CoN 4 moieties. The highly graphitized carbon matrix in the catalyst is beneficial for enhancing the carbon corrosion resistance, thereby promoting catalyst stability. The unique nanoscale X-ray computed tomography verifies the well-distributed ionomer coverage throughout the fibrous carbon network in the catalyst. The membrane electrode assembly achieves a power density of 0.40 W cm –2 in a practical H 2 /air cell (1.0 bar) and demonstrates significantly enhanced durability under accelerated stability tests. The combination of the intrinsic activity and stability of single Co sites, along with unique catalyst architecture, provide new insight into designing efficient PGM-free electrodes with improved performance and durability.

25 ENERGY STORAGE↗

NASA NTRS2004

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Belieres, Jean-Philippe↗

NASA NTRS2005

Anti-Corrosive Powder Particles

The National Aeronautics and Space Administration (NASA) seeks partners for a new approach in protecting embedded steel surfaces from corrosion. Corrosion of reinforced steel in concrete structures is a significant problem for NASA structures at Kennedy Space Center (KSC) because of the close proximity of the structures to salt spray from the nearby Atlantic Ocean. In an effort to minimize the damage to such structures, coatings were developed that could be applied as liquids to the external surfaces of a substrate in which the metal structures were embedded. The Metallic Pigment Powder Particle technology was developed by NASA at KSC. This technology combines the metallic materials into a uniform particle. The resultant powder can be sprayed simultaneously with a liquid binder onto the surface of concrete structures with a uniform distribution of the metallic pigment for optimum cathodic protection of the underlying steel in the concrete. Metallic Pigment Powder Particle technology improves upon the performance of an earlier NASA technology Liquid Galvanic Coating (U.S. Patent No. 6,627,065).

Parker, Donald↗

NASA NTRS1989

Advanced rechargeable sodium batteries with novel cathodes

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg were realized in practical batteries. Other technological advantages include its chemical simplicity, absence of self-discharge, and long cycle life possibility. More recently, other high temperature sodium batteries have come into the spotlight. These systems can be described as follow: Na/Beta Double Prime-Al2O3/NaAlCl4/Metal Dichloride Sodium/metal dichloride systems are colloquially known as the zebra system and are currently being developed for traction and load leveling applications. The sodium-metal dichloride systems appear to offer many of the same advantages of the Na/S system, especially in terms of energy density and chemical simplicity. The metal dichloride systems offer increased safety and good resistance to overcharge and operate over a wide range of temperatures from 150 to 400 C with less corrosion problems.

Distefano, S.↗

DOE OSTI2021

High Performance PEFC Electrode Structures

Raytheon Technologies Research Center (RTRC) in collaboration with Ion Power Inc. and the University of Arkansas at Little Rock and the FC-PAD consortium executed a project that: (1) developed comprehensive models of oxygen and proton transport in cathode catalyst layers that provided new insights about losses associated with reducing platinum loading to 0.1 mg/cm 2 , (2) designed, fabricated, characterized, and tested cells featuring carbon-supported catalyst layers with low platinum loadings that met efficiency and power density targets set forth by the Hydrogen and Fuel Cells Technology Office, and (3) designed, fabricated, characterized, and tested novel catalyst structures. The modeling efforts produced eight scientific publications that shared new descriptions of oxygen and proton transport in catalyst layers with the broader technical community. The key physical insights from the models are expressed in straightforward algebraic expressions, facilitating easy adoption by other researchers. The models developed during the project explain why resistance to oxygen transport is inversely proportional to interfacial area of platinum – an observation that eluded quantitative explanation for a decade. The models quantitatively predict polarization when measured morphological parameters and transport properties are input. Membrane-electrode assemblies made during the project met stated goals for current at high voltage and power density at rated voltage for transportation fuel cells at the end of budget period 2. High performance was achieved by developing a diffusion layer with low resistance to oxygen transport and a PtCo/C cathode catalyst layer capable of supporting rapid proton and oxygen transport. The project was subsequently directed to curtail experimental work and focus on modeling during budget period 3. Ion Power Inc. developed new expertise in fabricating catalyst layers containing platinum-cobalt catalysts, and processing very thin membranes. The University of Arkansas at Little Rock developed novel nanocolumnar self-supported thin film electrocatalysts that can be grown on carbon supports using a simple high pressure sputter deposition method. The nanocolumnar microstructure provides adequate surface-to-volume ratio for efficient platinum utilization, and the conformal platinum shell with larger crystal grain sizes covering the carbon support surface may eliminate durability issues associated with catalyst dissolution, agglomeration, and carbon corrosion.

08 HYDROGEN↗

DOE OSTI2025

Mitigating X-ray-induced damage for accurate analysis of battery cathodes using transmission X-ray microscopy

Here, we investigate the impact of X-ray-induced damage on the evolution of battery cathodes using synchrotron transmission X-ray microscopy. In an operando coin cell, exposure to the X-ray beam can induce bubble formation, potentially rendering cathode particles electrochemically inactive and displacing particles from their initial position. However, utilizing external pressure on a pouch cell can mitigate bubble formation and its associated effects.

25 ENERGY STORAGE↗

DOE OSTI2021

Achieving Stable Molybdenum Oxide Cathodes for Aqueous Zinc‐Ion Batteries in Water‐in‐Salt Electrolyte

Abstract Layered MoO 3 represents a promising cathode for aqueous rechargeable Zn‐ion batteries, but the implementation of this material is limited due to the low conductivity and poor structural stability. A 30 m ZnCl 2 water‐in‐salt electrolyte (WISE) is introduced to a MoO 3 nanobelt cathode for the first time, significantly increasing the stability of MoO 3 cathodes compared to those in 3 m ZnSO 4 and 3 m ZnCl 2 . The Zn/MoO 3 cell in WISE unambiguously demonstrate significantly improved rate performance delivering 349, 253, and 222 mAh g −1 at 100, 500, and 1000 mA g −1 , denoting a 12× capacity increase of those achieved in 3 m electrolytes at 1000 mA g −1 . A capacity retention rate of 73% is achieved after (dis)charging at 100 mA g −1 for 100 cycles, and no obvious capacity fading is observed at higher current densities of 500 mA g −1 and 2 A g −1 . Specifically, the data suggest that the drastic fading in 3 m electrolytes can be attributed to the parasitic surface deposits on Zn originated from Mo dissolution and H 2 formation due to Zn corrosion and hydrogen evolution reaction, which are significantly suppressed in the WISE. The direct visualization of these side reactions is achieved for the first time in the Zn‐MoO 3 system, using an in situ optoelectrochemical measurement.

Wang, Lei↗

DOE OSTI2021

DEVELOPMENT OF STABLE ANODE AND CATHODE MATERIALS FOR RECHARGEABLE BATTERIES

Batteries have been employed in a variety of applications, such as portable electronics, electric vehicles (EVs), and stationary energy storage to preserve energy from other renewable sources (like wind or solar energy). The ultimate goal is to develop high energy density, long life span, better safety, and low cost of the batteries. However, current commercialized batteries (like lead-acid, zinc-alkaline, lithium-ion batteries (LIBs)) could not fulfill all the demands of diversified applications. LIBs predominate the market because of their high energy density. To achieve a higher capacity of the cell, high-nickel layered (Ni > 90%) cathode materials are promising candidates since they compose high specific capacity and discharge voltage. In chapter 1, an introduction to cell energy density and the development of high-nickel layered cathode materials along with associated obstacles of poor cycling stability and thermal stability have been discussed. Associated works like doping or surface coating have also been mentioned in this section. In chapter 2, Al doping in high-nickel layered cathode materials to enhance the structural and thermal stability was introduced. Uniform incorporation of Al doping is achieved by mechanical fusion and calcination processes. The Al doping not only decreased the Li/Ni mixing ratio but also enhance the thermal resistance to oxygen evolution because of strong Al-O bonding, which leads to elevated electrochemical and thermal stability. In chapter 3, TiN is implemented as a Ti dopant for high-nickel layered cathode materials to improve the electrochemical performance in the LIBs. The Ti not only diffused within the bulk structure but also formed segregation on the surface, which improved the structural stability and led to better cycling performance. Although LIBs deliver high energy density, safety concerns of flammable organic electrolytes have not been resolved yet. Therefore, the aqueous rechargeable zinc-ion batteries (ZIB) have been praised for their safe, low-cost, eco-friendly stationary energy storage, which is considered as a complementary system to LIBs. In chapter 4, the mechanism, advantages, and challenges of ZIBs would be given and the strategies for solving the zinc metal anode issues have been discussed in this section. In chapter 5, a polymer coating method was reported to facilitate Zn deposition/ stripping by coordination with Zn2+ and prevented direct contact with aqueous electrolyte to block corrosion side-reactions. With this coating, a boost in a lifetime (up to 400 hours) and lower polarization under extremely high current conditions (10 mA cm-2) have been achieved in repeated Zn deposition/ stripping cycling.

25 ENERGY STORAGE↗

DOE OSTI2024

Understanding the Interactions of Multiple Pits Under Freely Corroding Conditions

The interactions of two propagating pits on a single cathode surface were evaluated across variations in chloride concentration, water layer (WL), pit sizes, separation distance (x 2 ), and cathode size (L Cath ) under freely corroding conditions using Finite Element Methods (FEM). Calculated FEM current was utilized to predict stability based on the Galvele pit stability product. FEM predictions were utilized to train a neural network machine learning model for rapid stability predictions. Pit one is in the center of a circular cathode while pit two moves radially from the center pit. With two pits, the overall current in each pit is decreased with respect to a single pit, however, the total current is increased. Increasing WL and L Cath generally increased overall current in each pit and increased predicted maximum pit sizes. Increasing x 2 decreased current in pit two due to less cathode being available to support dissolution in proximity to pit two. Increasing chloride concentration from 0.6 to 3 M NaCl increased current, while increasing from 3 to 5.3 M NaCl decreased current. An overall increase in predicted pit size with increase in chloride concentration is predicted. A machine learning model was created to predict current and maximum pit size and captured underlying physics and predicted stability across the multidimensional parameter space.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Electrochemical Mitigation of Corrosion in Molten Chloride Salts During CSP Plant Operation

We are designing an electrochemical flow-cell for removal of corrosive impurities from molten chloride salt Gen3 Concentrating Solar Power (CSP) plants during plant operation. Corrosive impurities will inevitably form in molten chloride salts upon exposure to air and moisture. We previously showed that even small amounts of these impurities, especially MgOHCl, will be detrimental in Gen3 CSP plants, necessitating prohibitively expensive containment alloys and frequent replacement of corroded components. Pre-purification of salt with Mg metal at temperatures above 650 degrees C is the current method for removing corrosive impurities from chloride salts before they are introduced to CSP systems. However, this is not a suitable method for impurity removal during plant operation. First, this method will produce MgO particulates which will damage plant components. Second, Mg metal is solid at the low temperature point (500 degrees C), so the purification will not proceed at a fast rate. At the high temperature point, Mg is soluble. In this case, fast purification may proceed, but dissolved metal is likely to precipitate out in cold-temperature point components, causing damage. In contrast, our electrochemically driven method allows fast Mg-based purification to proceed at the low temperature point, without formation of harmful particulates and without the risk of Mg metal precipitation. This novel approach is inspired by electrorefining techniques that are widely employed in industrial metallurgy for removal of impurities from metals. Impurities in the incoming molten salt will be reduced to inert MgO at the cathode, which can be removed by periodically washing the cell with acid. Simultaneously, Mg dissolution at the anode will ensure salt composition is maintained, with no net removal of Mg2+. We have validated this electrochemical approach at lab scale under static conditions with batch rectors. Furthermore, we have performed analytical modeling and technoeconomic analysis to produce a preliminary engineering design for the purification flow cell.

CSP↗