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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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Selective leaching and solvent extraction of Lithium from spent batteries

Pre-extracting Li from spent lithium-ion batteries (LIBs) is crucial because the recovery efficiency of Li is low after other critical metals have been extracted. Traditional methods involving black mass roasting followed by water leaching have resulted in the extraction of 76 % Li and 61 % Al. However, pre-leaching Li from pretreated black mass using an oxalic acid solution at both ambient and elevated temperatures significantly improved results, achieving 98.1 % Li, 99.5 % Al, and 100 % Fe extraction while leaving Ni, Co, Mn, and Cu behind under optimal conditions. Oxalic acid crystals were recovered by refrigerating the leach solution at temperatures below 5 °C and were reused with nearly identical leaching efficiency. Selective extraction of Li from the oxalate leach solution was achieved using Cyanex® 936P under optimal conditions. Here, due to its extremely low Li extraction efficiency, Dichloromethane proved unsuitable as a diluent. Comparative extraction tests using Cyanex® 936P, Cyanex® 272, and DEHPA in kerosene demonstrated that Cyanex® 936P is an excellent extractant for Li, effectively separating it from other impurities. Under optimal conditions, 98.8 % of available Li was extracted using 20 % Cyanex® 936P, compared to 51.1 % with Cyanex® 272 and 39.9 % with DEHPA in kerosene. Additionally, stripping Li from Cyanex® 936P using H 2 SO 4 and HCl was explored, with HCl yielding the best performance.

Black mass↗
DOE OSTI2023

Novel Approaches and Technologies for Aging Management

As part of the application process for license renewal and subsequent license renewal, nuclear utilities must perform an evaluation to confirm that they have appropriately considered aging effects on plant structures, systems, components within the scope of the license renewal. This effort within the Light Water Reactor Sustainability program’s Risk-informed System Analysis pathway is focused on risk-informed and performance-based approaches for aging management of buried piping, specifically managing selective leaching degradation phenomena. Selective leaching is a commonly occurring aging and degradation mechanism in buried pipes at nuclear power plants. To better understand the extent of selective leaching and its effect on the health of buried components, the licensees currently rely on visual inspections and destructive examinations which require extraction of multiple buried components. This research explores technological solutions that may replace or supplement existing inefficient, costly, and labor-intensive methods used in aging management.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Gas-solid reaction-based selective lithium leaching strategy for efficient LiFePO 4 recycling

As the electric-vehicle market continues to expand, LiFePO 4 (LFP) batteries, valued for their intrinsic safety and cost-effectiveness, are being increasingly utilized. However, this widespread adoption highlights the urgent need for innovative and environmentally friendly recycling methods for spent LFP batteries due to their relatively low material value and the environmental challenges associated with traditional recycling processes. Here, in this study, we present a novel selective lithium leaching technique that involves a gas–solid reaction with chlorine gas. This method achieves a remarkable leaching efficiency of 99.8 % and a selectivity of 98.8 % at 200 °C within just 10 min, without generating acidic wastewater. The resulting LiCl solution was successfully converted into Li 2 CO 3 with an excellent purity of 99.5 %, while producing NaCl solution as the only byproduct. Notably, the olivine structure of the LFP was preserved as FePO 4 after lithium leaching. The regenerated LFP demonstrated excellent performance, retaining 94.1 % of its capacity after 150 cycles, while the lithium-leached FePO 4 delivered a reversible capacity exceeding 150 mAh/g. This approach not only enhances the efficiency of LFP recycling but also paves the way for more sustainable battery technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of Leaching Processes for the Recovery of Rare Earth Elements from Acid Mine Drainage Precipitates

Acid mine drainage (AMD) has been a challenge for mine operators to address and has had significant environmental impacts when there is a failure to address it. Fortunately, there is a regulation in the US that requires the treatment of AMD before water can be discharged into the environment. AMD is generated when sulfide minerals are exposed to water and air from mining. The acidic water then leaches metals from the surrounding rock, creating the potential for environmental contamination of this acidic water containing dissolved metals. AMD can contain high concentrations of metals like iron, aluminum, and manganese and also have been shown to contain trace concentrations of critical minerals, including rare earth elements (REEs). This environmental waste stream is now being researched as a potential source for REEs. There is a patented process for processing and extracting REEs from AMD which produces rare earth oxide preconcentrate (REOP) from AMD treatment precipitates and a final stage mixed rare earth oxide (MREO) product. This body of research examines a selective leaching process for each of these products and determines the activation energy associated with the leaching processes. Acid leaching with HCl was examined to selectively leach REEs from REOP while contaminant metals remained in the solid residue. The maximum leaching recovery of the REEs from the REOP was approximately 90% and an activation energy of 6.4 kJ/mol at pH 3.0. Ammonium chloride leaching was examined to selectively remove contaminant metals from a MREO product. The ammonium chloride process successfully leached major contaminant metals in excess of 85% recovery and had a maximum activation energy of 40.0 kJ/mol.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2025

Selectively extracting lithium from single and mixed cathode materials

With the burgeoning reliance on lithium-ion batteries for sustainable energy solutions and electric transportation, the environmental and resource management associated with battery disposal are increasingly critical. Addressing these challenges necessitates innovative recycling techniques that recover valuable battery components, particularly lithium. This research introduces a universal, eco-friendly approach tailored for the efficient selective extraction of lithium from both single and mixed cathode materials, achieving impressive selective leaching efficiencies of lithium (99.51 % for LFP, 90 % for NMC, and 97.24 % for mixed cathode). Surprisingly, leaching efficiency of lithium from NMC can be significantly improved by introducing LFP since LFP can remove the dense transition-metal salts on the surface of NMC. The extracted lithium is recovered as lithium carbonate with battery-grade purity. This study also highlights the reuse of formic acid and the adoption of oxygen as an oxidizing agent to prevent wastewater production. Therefore, this method provides a robust foundation for sustainable lithium battery recycling.

economically and environmentally feasible↗
DOE OSTI2025

Incorporation of Oxygen Carrier Recycle into Large-Scale Production of Cu-Based Oxygen Carriers

One of the greatest challenges in the chemical looping combustion (CLC) of solid fuels is developing an oxygen carrier material that is reactive and attrition resistant and can be prepared at a reasonable cost. Recent efforts in oxygen carrier development have followed two primary approaches: (1) using natural ores, such as ilmenite, or (2) developing highly attrition-resistant and reactive synthetic materials. Both approaches have shortcomings, namely, the low reactivity and incompatibility of ores with solid fuel CLC and the high cost and low durability of synthetic materials. Here, a different approach is taken where attrition is assumed inevitable and the recycling of spent oxygen carrier materials is incorporated into oxygen carrier manufacture. For solid fuel CLC, Cu-based oxygen carriers are attrited and are collected with fly ash. Copper oxides are more reactive with nitric acid than most ash materials, meaning that a copper-nitrate-rich leachate can be generated. This copper nitrate stream could then be reused in oxygen carrier synthesis by impregnation. For proof of concept, leaching experiments were conducted to verify that copper oxides are selectively leached from ash-containing spent oxygen carriers. Several cases for process design are proposed based on the composition of spent materials, as the degree of copper oxidation and type of solid fuel dictate leaching residence times and general processing intensity. The four stages proposed here include impurity removal, copper leaching and recovery, solid–liquid separation, and evaporation/concentrating. The resulting process should be able to recover up to 95% of copper while minimizing inclusion of undesirable ash-based impurities.

anions↗
DOE OSTI2020

Low-Temperature Plasma Treatment for Enhanced Recovery of Highly Valued Critical REEs from Coal (Final Report)

The principle objective of this project was to develop a novel process flowsheet using low-temperature plasma treatment (LTP) integrated with conventional hydrometallurgical processes to recover rare earth elements (REEs), especially highly valued REEs (i.e. scandium and critical REEs), from coal and coal byproducts. LTP treatment was used to pretreat the solid feed material prior to leaching in an effort to improve the leaching characteristics of the REEs and potentially reduce acid consumption. Initially, a detailed experimental program was performed on a laboratory LTP furnace to identify a set of process parameter values to be used for assessing the enhanced leaching performance achieved on four specific gravity fractions of West Kentucky No. 13 and Fire Clay coarse coal refuse materials. High-temperature oxidation (HTO)) was also evaluated as a means for improving REE leachability on the same fractions of both coal sources. The lixiviants used to assess leachability improvements included: i) untreated water, ii) 0.1 M ammonium sulfate solution and iii) 1.2 M sulfuric acid solution at a temperature of 75°C. The laboratory data was used to develop multiple process flow sheets using HTO only to produce a rare earth oxide mix concentrate or utilizing both LTP and HTO treatment processes to generate a high purity heavy REO mix concentrate and a light REO mix concentrate. A techno-economic analysis was performed on each circuit. Low-temperature plasma oxidation was found to enhance REE leaching characteristics for all specific gravity (SG) fractions of the West Kentucky No. 13 coarse refuse material. The leaching recovery improvement was preferentially achieved for the heavy REEs with higher values obtained when treating the lower density fraction material. For example, the leaching recovery for the heavy REEs in the untreated 1.6 SG Float fraction material was 8% in a 0.1 M ammonium sulfate solution. After LTP treatment for 32 hours, heavy REE recovery increased to 33%. The corresponding recovery value for the light REEs was 10%. These findings indicate a strong affinity of the heavy REEs with the organic material, which is the component being reduced in content during the LTP treatment. Scanning electron micrographs showed the development of a honeycomb structure with increased LTP treatment with higher surface area as confirmed from BET measurements. Higher surface area promotes improved leaching efficiency due to enhance chemical interactions. When using 1.2 M sulfuric acid, the LTP treatment was found to provide a heavy REE recovery increase from 23% to 53% for the 1.6 SG Float fraction which corresponded to an ash content increase from around 20% to 35%. However, LTP treatment provided no improvement in leaching characteristic for the 2.2 SG sink material in the acid solution, which was likely due to the low organic content. The LTP treatment of the Fire Clay SG fractions provided no improvement in REE leaching characteristic, which may be due to the association with REE minerals such as monazite and REE-associated mineral matter such as clays. High temperature oxidation using temperatures in the range of 600-750OC was found to significantly enhance the leaching characteristics of both the light and heavy REEs for all density fractions in both coarse coal refuse materials. Generally, the increase in light REE recovery for the West Kentucky material was from 15% for the untreated material to 90% for the HTO treated material at 600°C. Recovery values dropped significantly when using temperatures below 600°C and above 750°C. The impact of the excessive temperatures was most likely a result of sintering. For the heavy REEs, HTO significantly improved recovery in the lighter SG fractions, which may be due to an affinity with the organic content. Only limited heavy REE recovery improvement was obtained for the denser SG fractions. Another benefit of HTO is the conversion of calcium-based minerals to a very soluble calcium oxide, which is removable using a mild acid solution, and the conversion of Fe minerals to relatively insoluble minerals such as hematite and magnetite. The pregnant leaching solution produced from the leaching of all SG fractions obtained from both coal sources was treated using two stages of solvent extraction procedurally modeling a rougher-cleaner circuit followed by oxalic acid precipitation. Rare earth oxide products having a purity greater than 97% was produced from nearly all of the SG fractions. A novel process flowsheet was developed based on the selective leaching of heavy REEs that was made possible through LTP treatment of West Kentucky No. 13 coarse refuse followed by salt leaching. In the flowsheet, coal refuse material is ground to a top size of 1mm and then treated by LTP. The treated material is mixed into a 0.1 M ammonium sulfate solution and then filtered to produce a heavy REE enriched pregnant leach solution. The heavy REEs are concentrated by two stages of selective precipitation to produce a heavy REE mix oxalate and then roasted to obtain a heavy REO mix concentrate. The solid residues remaining after salt leaching is dried and then subjected to HTO treatment followed by concentration using selective precipitation and roasting to produce a light REO mix concentrate. An alternative circuit was developed using HTO treatment only to treat 100% of the coarse refuse material followed by selective precipitation and roasting to generate a high purity REO mix product. A techno-economic analysis performed for the treatment of West Kentucky No. 13 and Fire Clay coarse refuse based on a hypothetical 500-tph plant revealed that the net present value for all scenarios was significantly negative. Primary reasons include: i) a substantial decrease in the basket value of the final product relative to the feed and ii) high chemical costs relative to the amount of product generated. The basket value reduction was primarily due to little to no scandium recovery due to poor leaching characteristics when using low acid concentrations as necessitated by the low feed grades. Operating costs were primarily influenced by the chemical costs relative to the kilograms of concentrate produced and feed grade. For the Fire Clay coarse refuse material, the total operating cost was estimated to be $354 per kg of REO produced which was higher than the basket value of the REO product ($276/kg). Approximately 37% of the total cost was the sulfuric acid used during the leaching process. A comparative analysis performed to assess the economic viability of using low-temperature plasma furnaces found that market value enhancement for the generation of both heavy REO and light REO concentrates will be needed in addition to significant technology advancements to reduce the cost of plasma furnaces.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Sustainable Urban Mining of Critical Elements from Magnet and Electronic Wastes

Here, we created a straightforward and environment-friendly process for acid-free leaching of rare-earth elements and cobalt, which are vital materials, from waste magnet materials. The process also allows for selective leaching of rare-earth elements from magnet-containing electronic wastes, such as end-of-life hard disk drives and electric motors. The use of copper salts eliminates the use of volatile toxic acids in the dissolution and separation processes, which provides for a more eco-friendly approach to recovering critical elements and a safer work environment. Recovered critical materials were shown to be suitable for reinsertion into the materials supply chain.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Separation of cobalt, nickel, and manganese in leach solutions of waste lithium-ion batteries using Dowex M4195 ion exchange resin

Current methods to separate and recover critical metals from waste lithium-ion battery (LIB) scrap require multiple unit operations that involve selective leaching and a combination of separation methods. These methods include impurity removal, solvent extraction, ion exchange, and precipitation, to achieve high purity Co and Ni products. In this paper an efficient extraction strategy was developed to individually separate Ni and Co from a LIB leachate that was generated from an electrochemical leaching process. By using Dowex M4195 resin, as the only method of separation, additional impurity removal operations were not needed. After loading and eluting, three different fractions were obtained: 99.0% Ni concentrate, 98.5% Co concentrate, and a Li/Mn rich concentrate allowing the separation of Ni, Co and Mn. Here, the developed process is then presented as an alternative for metal recovery from leachates from scrap LIBs with minimum chemical addition and pH adjustment.

36 MATERIALS SCIENCE↗
NASA NTRS1984

The chemical durability of tektites - A laboratory study and correlation with long-term corrosion behavior

Leach tests carried out on tektite specimens (indochinites and australites) under high-dilution conditions show a common behavior characterized by low leach rates (0.00018 g/sq m per d, or 7.2 x 10 to the -12th m/d at 23 C) and an activation energy of (79,600 + or - 700 J/mol). The extent of selective leaching is very small, of the order of 10 to the -8th m. Extrapolation of test results over the lifetime of the tektites gives an excellent agreement with field observations on the extent of corrosion, and this is an important step in establishing the validity of laboratory tests as a basis for the development of models and predictions concerning long-term durabilities at least in the limiting case of high dilution or rapid flow. The results are also shown to be in agreement with various previous observations on the corrosion resistance of tektites. The chemical durability of tektites is observed to be consistent with their composition, highlighting requirements of high corrosion resistance in glasses; these requirements include a silica content in excess of 67 mol percent, an extremely low water content, and an alkali content which is low both absolutely and relative to the di- and poly-valent metal oxide levels. It is shown that artificial glasses which fulfil these criteria are no less corrosion-resistant than the corresponding natural glasses. These conclusions have bearing on the development, as well as on the evaluation, of glasses intended for very long service, such as radioactive waste vitrification media.

Barkatt, A.↗
DOE OSTI2021

Data for "Relative Reactivity and Bioavailability of Mercury Sorbed to or Coprecipitated with Aged Iron Sulfides"

The potential for inorganic mercury (Hg) to be converted to methylmercury depends, in part, on the chemical form of Hg and its bioavailability to anaerobic microorganisms that can methylate Hg. In anaerobic settings, Hg can be associated with sulfide phases, including ferrous iron sulfide (FeS), which can sorb or coprecipitated with Hg. The objective of this study was to determine if the aging state of FeS alters the Hg coordination environment as well as the reactivity and bioavailability of sorbed and coprecipitated Hg species. FeS particles were synthesized with and without Hg2+ and aged in anaerobic conditions for multiple time frames spanning from 1 hour to 1 month. For FeS particles synthesized without Hg, Hg2+ was subsequently sorbed to the FeS for 1 day. Analysis of Hg speciation of these materials by X-ray absorption near edge spectroscopy revealed a predominance of 4-coodinate Hg-S species in the sorbed Hg-FeS solids and a mixture of 2- and 4-coordinate Hg-S in the coprecipitated Hg-FeS. The leaching potential of the Hg was assessed by exposing the particles to a solution of dissolved glutathione (a thiolate-based Hg chelator). As expected, the sorbed Hg-FeS released more soluble Hg compared to the co-precipitated Hg-FeS. However, when these particles were exposed to Desulfovibrio desulfuricans ND132 (a known Hg methylator), more Hg was methylated from the co-precipitated Hg-FeS than the sorbed Hg-FeS, consistent with expectations from the Hg-S coordination state and inconsistent with the selective leaching results. Overall, these results suggest that the bioavailability of particulate Hg cannot be easily discerned by leaching potential into bulk solution. Rather, bioavailability entails more subtle interactions at particle-cell interfaces and perhaps correlates with the local Hg-S coordination state in the particles. This data package contains data shown in the referenced publication, including all figures. Each figure is available in the respective *.csv file and a summary of all files are also included in the the xlsx file. Additional formatted data include X-ray diffraction data of the FeS solids are also available in a HPF format (Panalytical software), X-ray absorption spectroscopy data as *.prj files (Athena), and X-ray fluorescence data in its raw data form.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Examining the effects of chemical cleaning, leaching, and partial dissolution on zinc and cadmium isotope fractionation in marine carbonates

The application of zinc (Zn) and cadmium (Cd) isotopes as palaeo-proxies in carbonate sediment is rapidly expanding due to their potential for tracing changes in biological productivity in the modern and past oceans. However, there are limited investigations into the chemical cleaning methods required to produce the most consistent and accurate data for these novel isotope systems. This could impact their use as palaeo-proxies to reconstruct ocean-atmosphere-climate interactions throughout Earth's history. To address this concern and expand the utility of the Zn and Cd stable isotope systems as palaeo-productivity tracers, the performance of two standard chemical cleaning protocols for acquiring robust and reliable Zn and Cd isotope datasets were assessed. These include (i) the Cd-cleaning method that uses a reductive step to selectively leach contaminating secondary iron (Fe)-manganese (Mn) (oxyhydr)oxide coatings from the carbonate surface, and an oxidative step that is used to remove post-depositional organic matter and sulphide precipitates; and (ii) the magnesium/calcium cleaning protocol that includes an oxidative step only, leaving secondary Fesingle bondMn (oxyhydr)oxide coatings largely intact. Well-preserved Holocene-, and Mesozoic-aged carbonate sediments were used to test the reliability of these two chemical cleaning methods. The Holocene samples comprised not only aliquots of bulk sediment, but also individual species of planktic and benthic foraminifera. Our results show that the best practice chemical cleaning method for retrieving consistent and accurate Zn and Cd isotope, and Zn/Ca and Cd/Ca datasets for carbonate sediments, requires both reductive and oxidative cleaning following the Cd-cleaning method. This differs from most methodological approaches applied to date that remove the reductive step from the chemical cleaning protocol and apply an oxidative step only, or no chemical cleaning at all. Inclusion of the reductive step in the chemical cleaning method typically shifts δ 66 Zn by ~0.1‰ lower and δ 114 Cd by 0.3‰ higher in the solid phase, while Zn/Ca and Cd/Ca typically decrease 2-fold. The benthic foraminifera, C. wuellerstorfi, that live in ocean bottom waters where the seawater Zn and Cd isotope composition is homogeneous display evidence of Zn and Cd isotope fractionation between seawater and carbonate on the order of 0.08 ± 0.08‰ (2SE, n = 4) and -0.25 ± 0.13‰ (2SE, n = 4), respectively, in agreement with experimental constraints. Furthermore, evidence of Zn isotope fractionation effects are recorded in a naturally-dissolved carbonate sediment, together with laboratory-controlled carbonate dissolution experiments. Based on these results, we recommend the Cd-cleaning method and the application of Zn and Cd isotope fractionation factors to accurately reconstruct past seawater Zn and Cd isotope compositions from carbonate sediments.

58 GEOSCIENCES↗
DOE OSTI2025

Impact of organic acids on extraction of rare earth elements: Mechanisms and optimization

Organic acids are increasingly recognized as an environmentally friendly and efficient selective leaching agent of critical minerals. However, their impact on subsequent extraction processes remains unclear. This study investigates the extraction behavior of rare earth elements (REEs), representative of critical minerals, in the presence of various organic acids, including citric acid, maleic acid, malonic acid, DL-malic acid, L(+)-tartaric acid, and L-ascorbic acid. The results show that organic acids slightly reduce the extraction of REEs but greatly increase the extraction of aluminum (Al³⁺), making it harder to separate REEs from other elements. To avoid this, it is best to keep organic acid concentrations as low as possible in practical applications. However, by optimizing extraction conditions, these negative effects can be minimized. Specifically, adjusting the contact time between solutions allows for efficient REE extraction while limiting unwanted aluminum extraction. Among the acids tested, malonic acid and L(+)-tartaric acid were found to be the most effective for selectively extracting REEs. Mechanistically, organic acids are likely to form complexes with REEs and D2EHPA during extraction, except for Y (III), offering practical guidelines for optimizing REE recovery. Beyond extraction, this study also highlights a way to recover organic acids by precipitating REEs from stripping solutions using oxalic acid, which adds both environmental and economic benefits. Furthermore, these findings provide useful insights for optimizing REE recovery and offer a reference for extracting other critical minerals from solutions containing organic acids.

D2EHPA↗
DOE OSTI2021

Intergranular precipitation-enhanced wetting and phase transformation in an Al0.4CoCrFeNi high-entropy alloy exposed to lead-bismuth eutectic

We report after exposure to oxygen-poor (10 -13 –10 -14 wt%) liquid lead-bismuth eutectic (LBE) at 500 °C for 500 h, LBE penetrates more than one order of magnitude deeper in an FCC Al 0.4 CoCrFeNi high-entropy alloy (HEA) decorated with a network of BCC (Ni, Al)-rich intergranular (IG) precipitates than in a single-phase, FCC Al 0.3 CoCrFeNi HEA without the IG precipitate network. This deterioration of corrosion resistance is attributed to the energetic nature of the BCC/FCC interphase boundaries (IBs) and resultant IB wetting. The LBE ingress film selectively leaches nickel located at those low-indexed crystalline planes, resulting in phase transformation from FCC to BCC structure.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Effect of tellurium concentration on the corrosion and mechanical properties of 304 stainless steel in molten FLiNaK salt

In this study, the effect of Te concentration in molten FLiNaK salt on the corrosion and mechanical properties of 304 stainless steel was investigated. The corrosion depth of samples after the immersion tests for 48 h at 600 °C decreased with increasing Te concentration. Likewise, the sample after the immersion test containing 1.0 wt% of Te (1.0 wt% Te sample) showed less reduction in mechanical properties than the 0.1 wt% Te sample. We hypothesize that the condition for a Cr-oxide layer that has the protective property is fulfilled underneath the Ni-Fe rich layer which is formed by the selective leaching of Cr.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A green closed-loop process for selective recycling of lithium from spent lithium-ion batteries

As the economy started to recover from the COVID pandemic, the price of Li 2 CO 3 skyrocketed to its highest. This situation has aggravated concerns about the supply chain for lithium-ion batteries (LIBs). Recycling spent LIBs is a potential solution to alleviate the bottleneck of the supply chain and prevent environmental pollution, and has attracted lots of attention. However, lithium recycling is generally disregarded because of the complex recycling process and its low recycling efficiency. Here, in this work we developed a sustainable lithium recovery process, which can selectively leach and recover lithium with formic acid before recycling valuable metals. With the reported method, lithium can be 99.8% recovered from layered oxide cathode materials with 99.994% purity. In addition, this lithium recovery process is affordable, compared to the typical hydrometallurgical process, by saving 11.15% per kilogram of spent LIBs. Therefore, this research provided a new solution to eliminating the effects of lithium ions on valuable metal separation and the co-precipitation reaction and precluding the influence of other metal ions on lithium recovery. Finally, this simplified lithium recovery process provides new opportunities for sustainable recycling of LIBs and economical restoration of the lithium supply chain.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Editors’ Choice—Molten Salt Electrolysis in Chloride Melts for Energy-Efficient Iron Metal Production

This study explores chloride molten salt electrolysis (CMSE) as a promising route for energy-efficient iron metal (Fe) production. Moderate temperature (500 °C) LiCl-KCl molten salts offer excellent thermodynamic stability, high ionic conductivity and diffusivity, and high solubility for FeCl 3 , thereby enabling efficient Fe metal extraction at high electrowinning rates. Here, we demonstrate the two essential steps for converting taconite ore into Fe metal. First, Fe 2 O 3 from taconite pellets was selectively leached in HCl yielding a high-purity FeCl 3 aqueous solution, while the gangue components settled at the bottom. Then, anhydrous FeCl 3 was electrolyzed in a LiCl-KCl eutectic molten salt at 500 °C at high current density (1 A cm −2 ) and at high Coulombic efficiency (>85%). Analysis of the electrowon Fe deposits revealed dendritic structures with purity of >99 wt%, which could be further improved to nearly 100 wt% through arc re-melting. CMSE offers low specific energy consumption (3.7 kWhr kg −1 ), competitive with H 2 -DRI and other electrolytic approaches being pursued globally. Our findings underscore the potential of CMSE as an energy-efficient route for electrosynthesis of Fe metal.

36 MATERIALS SCIENCE↗