17 Search Results

Tristructural isotropic (TRISO)-coated fuel particles are designed for use in high-temperature gas-cooled nuclear reactors, featuring a structural SiC layer that may be exposed to oxygen-rich environments over 1000 °C. Surrogate TRISO particles were tested in 0.2–20 kPa O₂ atmospheres to observe the differences in oxidation behavior. Oxide growth mechanisms remained consistent from 1200–1600 °C for each P_{O$$_2$$}, with activation energies of 228 ± 7 kJ/mol for 20 kPa O₂ and 188 ± 8 kJ/mol for 0.2 kPa O₂. At 1600 °C, kinetic analysis revealed a change in oxide growth mechanisms between 0.2 and 6 kPa O2. In 0.2 kPa O₂,more » oxidation produced raised oxide nodules on pockets with nanocrystalline SiC. Oxidation mechanisms were determined using Atom probe tomography. Active SiC oxidation occurred in C-rich grain boundaries with low P_{O$$_2$$}, leading to SiO₂ buildup in porous nodules. Here, this phenomenon was not observed at any temperature in 20 kPa O₂ environments.« less

The electrification of transportation and the transition of society towards low or net-zero carbon emissions has led to a skyrocketing global demand for Li-ion batteries. After a service life of three to ten years, Li-ion batteries have less than 80 % of their initial capacities and draw near to the end of their lives for practical utilization. Due to potential supply chain shortages and the value embodied in Li-ion batteries, it is imperative to recycle them, to recover the materials, and to improve the circularity and the sustinability of the industry. How to cost-effectively purify spent batteries while reducing time,more » energy, and waste emissions is a challenge faced by Li-ion battery recyclers. The first electrochemical membrane reactor reported in our group hasa high selectivity towards lower Cu²⁺, Al³⁺ and Fe³⁺ ions (<5 ppm) and retains >95% of the Ni²⁺, Co²⁺ and Mn²⁺ ions in the leachate. An advanced electrochemical membrane reactor was developed in this study. Further, not only does the new reactor have the same selectivity as the original reactor, but other advantages including a faster leachate processing rate (up to 10X faster). The advanced reactor can also directly generate acid at the anode side; eliminating the reactor restoration step. The prominent advantages that this electrodialysis technology has over chemical-precipitation methods include: (1) ion recovery efficiencies do not diminish after removing the impurities, Ni²⁺, Co²⁺ and Mn²⁺, even at a higher initial Ni²⁺ ion concentrations; in comparison, chemical precipitation has Ni²⁺, Co²⁺ and Mn²⁺ ion recovery efficiencies reduced significantly when the initial Ni²⁺, Co²⁺ and Mn²⁺ ion concentrations increase. (2) electrodialysis does not change the concentrations of Ni²⁺, Co²⁺ and Mn²⁺ ions significantly, but chemical precipitation could reduce Ni²⁺ and Co²⁺ ions to less than half of their initial values. Through electro-dialyzing the leachate, the H₂ evolution reaction mechanism was found to switch from the Volmer-acid Heyrovsky mechanism to the Volmer-alkaline Heyrovsky mechanism at a pH of around 3.7.« less

The isolation of Ni/Co double salts can be recovered by fractional precipitation with ammonium sulfate. The elemental analysis of these isolated double salts shows a total metal composition of >99% of Ni, Co, and Mn with negligible impurity metals.

The ongoing evolution in energy production and conversion technologies has brought solid oxide electrochemical cells (SOCs) to the forefront, recognized for their high efficiency and environmental benefits. However, establishing sustainable and scalable manufacturing processes for SOCs presents formidable challenges, including sourcing large-scale raw materials and implementing effective recycling methods for spent cells and manufacturing scraps. In response, we demonstrate closed-loop direct recycling of proton-conducting solid oxide electrochemical half cells, incorporating active comminution and cell regeneration using the recycled materials. This innovative approach achieves over 92 % material recovery and an impressive 100 % recovery in full cell performance, addressing amore » significant gap in current sustainable manufacturing practices while setting a new standard for the industry. This technology not only addresses a significant gap in current sustainable manufacturing practices but also sets a precedent for future advancements in the sustainable SOC field, potentially influencing broader practices in the recycling of multi-functional ceramics.« less

The use of electrons as main reagent for the recovery and recycling of critical metals from spent lithium-ion batteries (LIBs) is a process electrification strategy that can be used to close the life-cycle loop of LIBs through more sustainable methods. Electrochemical leaching, a process that uses a reductant that is constantly regenerated electrochemically for the leaching of lithium-ion battery black mass (LIBBM), has shown high extraction efficiencies and sustainable scores. However, slow kinetics, reactor design challenges and lack of deeper understanding of the underlying processes are barriers to the optimization, scale-up, and market adoption of this technology. In this paper,more » a kinetic study and mathematical model for dissolving LIBBM is presented to better understand the underlying mechanisms aiming to reduce the processing time and make predictions for future design and scale-up. The effect of acid and electrochemically mediated reductant concentrations, LIBBM loading, and cathode/reactor designs were explored. As a result, the leaching time was reduced from 7h to under 1h at a pulp density of 73 g/L, without external heating. A novel reactor with parallel baffle electrodes (PBE) was developed, which significantly reduced the leaching time by improving convection in a stirred slurry electrochemical reactor. Dimensionless numbers were deduced from an unsteady state model, which can be used in dimensional analysis for future process design and scale-up.« less

To advance dimethyl ether-driven fractional crystallization (DME-FC), a more sustainable method of water treatment and mineral recovery, a range of chemical equilibria were measured. These include varying concentrations of miscible organic solvents (MOS) used to experimentally measure the solvent-induced solid-liquid equilibrium (SLE) of calcium sulfate (CaSO₄) in water. Seven MOS, including dimethyl ether (DME), acetonitrile (MeCN), 1,4-dioxane, tetrahydrofuran (THF), acetone, ethanol, and diethylamine, were screened to establish trends associated with molecular volume, functional groups, and physical properties. The effect of MOS on CaSO₄ removal differed at concentrations <0.15 mol fraction MOS; MOS with greater molecular volume (THF, 1,4-dioxane, and diethylamine)more » induced greater CaSO₄ precipitation on a per mole basis. The solvent-induced SLE for all MOS converged between 0.15 and 0.2 mol fraction MOS, reaching a CaSO₄ concentration consistent with a water to MOS hydration ratio of 5:1 to 6:1, which may correspond to the solvent generating a solution-based pseudo-clathrate structure with continuity within the solution. Finally, solution pseudo-clathrate structures provide a mechanistic basis for DME-FC.« less

The manufacturing of lithium-ion batteries (LIB) requires critical materials such as cobalt (Co) and lithium (Li) that are essential for clean-energy products including electric vehicles. Because of their rapidly increasing demand and limited supply, the recycle and reuse of these materials from end-of-life LIB have garnered a lot of interest. Electrochemical leaching has emerged as a sustainable method to extract critical materials out of LIBs, so life cycle assessment was conducted to compare the environmental impacts with traditional peroxide-based leaching and another emerging technology – SO₂-based leaching. The results showed that electrochemical leaching reduces the global warming potential (GWP) bymore » 80%-87% compared to peroxide-based leaching due to a lower acid consumption, avoidance of hydrogen peroxide, and regeneration of reducing agent iron (II) sulfate and compares well with SO₂-based leaching in most impact categories. Furthermore, the analysis suggested renewable energy can further reduce the environment footprint of electrochemical leaching.« less

Recovery of critical materials from end-of life (EOL) lithium-ion batteries (LIB) is gaining interest as demands for materials grows. Hydrometallurgical processes start with an intermediate product known as black mass which contains critical materials of interest (Co, Ni, Li, and graphite) as well as impurities such as Cu, Al, and Fe. These impurities are deleterious to downstream separation processes, as well as impact functionality of the final products. Here, these impurities effectively compete with most solvent extraction (SX) and metal recovery processes to diminish the overall yields of the desired materials. In this work, a process flowsheet is presented wheremore » a previously reported electrochemical leaching (ECL) process is followed by selective precipitation using diammonium hydrogen phosphate (DAP) to remove Cu, Al, and Fe from LIB leachate solutions. The electrochemical leach process removes Cu and produces a pH-adjusted leachate, ca. pH 2, without requiring an extra Cu extraction step. The addition of the precipitant DAP to leachate by slightly adjusting the pH to 3–4 at 45 °C, precipitates 95–99% of Al and Fe as their phosphates and the leachate retains >95% of Co, Ni and Li. After the filtration of phosphate impurities, the solution is ready for further processing, such as SX. As an unexpected result from the leachate processing, 20–30% of the Ni and Co co-crystalize as the double salt after cooling to room temperature, which could provide a shorter route to their recovery.« less

Abstract Surrogate tristructural‐isotropic (TRISO)‐coated fuel particles were oxidized in 0.2 kPa O ₂ at 1200–1600°C to examine the behavior of the SiC layer and understand the mechanisms. The thickness and microstructure of the resultant SiO ₂ layers were analyzed using scanning electron microscopy, focused ion beam, and transmission electron microscopy. The majority of the surface comprised smooth, amorphous SiO ₂ with a constant thickness indicative of passive oxidation. The apparent activation energy for oxide growth was 188 ± 8 kJ/mol and consistent across all temperatures in 0.2 kPa O ₂ . The relationship between activation energy and oxidation mechanism is discussed. Raised nodules of porous,more » crystalline SiO ₂ were dispersed across the surface, suggesting that active oxidation and redeposition occurred in those locations. These nodules were correlated with clusters of nanocrystalline SiC grains, which may facilitate active oxidation. These findings suggest that microstructural inhomogeneities such as irregular grain size influence the oxidation response of the SiC layer of TRISO particles and may influence their accident tolerance.« less

The expanding electric vehicle market brings with it exponential growth in the use of lithium (Li)-ion batteries (LIB) for which a wave of spent LIB is expected to come within the next 5 to 10 years. Due to the economic and strategic value imbedded within the metals contained in LIB, different recycling technologies, including hydrometallurgy, pyrometallurgy and direct recycling, are under development. Being different from previous hydrometallurgical methods, which may have high chemical consumption and negative environmental impact, an electrochemical membrane reactor is designed and validated for the first time, to electrify and decarbonize the impurity removal process. This reactormore » electroplates copper (Cu) and electrochemically precipitates aluminum (Al) and iron (Fe) from simulated spent LIB leachates, by consuming only air, water, and electricity, and the impurities are reduced to <1 ppm. The purified leachate maintains 99.5 % of the nickel (Ni), 95.4 % of the cobalt (Co) and 99.14 % of manganese (Mn) from the original leachate solution, and then can be directly applied for cathode precursor synthesis. Additionally, the purification process doesn’t introduce extra impurity, and the reactor restoration process generates valuable by-product hydro sulfate (H2SO4). This electrochemical process can reduce the cost, because of the much less chemical consumption and the valuable by-product generation, and mitigates the waste emissions, because of no extra impurity introduced and no greenhouse gas (GHG) produced. In conclusion, the chemical precipitation method uses significant amount of NaOH, which induced GHG emission during the manufacturing process.« less