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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 271 records · Page 15

Enabling Bipolar Membrane Manufacturing Using Microscopy

Bipolar membranes (BPMs) used for water treatment suffer from interface instabilities, causing premature failure and decreased performance. Recent research has highlighted the impacts of membrane morphology on mechanical behavior and performance. Improved material performance of thin film membranes requires enhanced transport properties coupled with better control of the mechanical characteristics to avoid premature failure of the film. Thus, morphology is a key parameter when developing and evaluating novel membrane materials. Microscopy offers unique advantages for nano-scale characterization of thin film membrane interfaces and morphologies. In this study, the interface junction of BPMs was evaluated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). BPMs were fabricated using (1) hot pressing lamination, (2) bench-scale solution casting, and (3) roll-to-roll sequential casting (R2R). Both commercial and in-house fabricated ion exchange membranes were used in the BPMs. The BPMs were comprised of a cation exchange membrane and an anion exchange membrane with a catalyst layer sandwiched in between. Cross sectional SEM and EDX images of the membrane interface junction were compared among the different fabrication techniques and materials. The bench cast catalyst layers were nonuniform compared to the R2R and hot pressed membranes, demonstrating the importance of precise catalyst application conditions. Different thicknesses of the BPMs and individual membrane layers revealed that polymer solution concentration needs to be optimized during manufacturing. This work shows that microscopy can identify key processing parameters that affect BPM interface junction quality at the microscale to enable manufacturing of high performance BPMs.

36 MATERIALS SCIENCE↗

Final Scientific/Technical Report: Simultaneous Lithium Extraction and Thin-Film Deposition of Lithium Metal for Low-Cost, High-Energy Anodes from Brine Resources

This report describes the scale-up and pilot validation of Alpha-En's Reductive Lithium Extraction (RLE) process, which directly converts lithium ions from aqueous brine-derived feedstocks into thin-film lithium metal anodes, demonstrating greater than 50% extraction efficiency, battery performance matching or exceeding commercial lithium metal controls in coin and pouch cells, and continuous roll-to-roll production of a meter-scale lithium metal anode strip.

25 ENERGY STORAGE↗

Photonic Curing of Nickel Oxide Transport Layer and Perovskite Active Layer for Flexible Perovskite Solar Cells: A Path Towards High-Throughput Manufacturing

High-throughput roll-to-roll (R2R) manufacturing of perovskite solar cells (PSCs) is currently limited by thermal processes that take tens of minutes each, translating to impractically long annealing tools at high web speeds. In addition, PSCs are usually made with metal oxide transport layer materials that require high temperatures for thermal annealing. Here, we demonstrate the fabrication of PSCs using photonic curing, instead of thermal annealing, to convert NiO x directly from sol-gel precursors for hole transport layers and to crystallize methylammonium lead iodide (MAPbI 3 ) active layers on flexible Willow ® Glass substrates. Photonic curing uses short, intense pulses of light to process materials at a high speed, hence it is compatible with R2R manufacturing. We achieved power conversion efficiencies (PCEs) of 11.7% in forward-scan and 10.9% in reverse-scan for PSCs made with photonic cured NiO x and MAPbI 3 films. Furthermore, both NiO x and MAPbI 3 films could be processed with a single photonic curing pulse, with a web speed of 5.7 m/min, and still produce PCEs comparable to thermally annealed control samples. Based on the single-pulse photonic curing condition for each film, we project a web speed of 26 m/min, laying a pathway to high-throughput production of perovskite solar modules.

14 SOLAR ENERGY↗

An Experimental Investigation of Multilayer Flow in a Slide Die Coating Process

Roll-to-roll coating technology has been actively applied not only for conventional film production but also for emerging energy devices such as organic solar cells, organic light emitting diodes, batteries, smart windows, and fuel cells. The devices are multilayer structures requiring several coating and drying steps when implemented in a serial fashion, which increases capital costs and energy consumption. Simultaneous multilayer (ML) coating technologies present an opportunity for cost reductions and improved process efficiency by reducing equipment footprint and the number of process steps. In this talk, we experimentally investigate ML slide die coating flow for the manufacturing of fuel cell membrane electrode assemblies (MEAs). For ML slide coating, understanding fluid properties such as density, surface tension, and viscosity are necessary for stable flows and limiting intermixing of the miscible layers. Here, we utilize a design-of-experiment methodology - Box-Behnken design (BBD) - to correlate ink formulation parameters to fluid properties. Using the ink properties obtained from the BBD, we performed numerical flow simulations to obtain a proper process conditions to guide experimental coating trials. Finally, experimental verification is performed on a ML slide die and a degree of miscibility was observed for various ink formulation conditions.

28 EE - Advanced Manufacturing Office (EE-5A)↗

Reverse martensitic transformation on the corrosion behavior of a 2304 lean duplex stainless steel

This study investigates the influence of the reverse martensitic transformation on the corrosion behavior of 2304 lean duplex stainless steel (LDSS) at low temperatures (400–600°C). The steel underwent cold rolling, followed by isochronal annealing for 0.5 h. Phase transformations and microstructures were analyzed using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Corrosion resistance was evaluated using a syringe cell with cyclic potentiodynamic polarization in 0.6 M NaCl solution and double-loop electrochemical potentiokinetic reactivation in 0.5 M H 2 SO 4 + 0.001 M KSCN solution. A bimodal breakdown potential behavior, associated with either pitting or transpassivity, was observed in the as-received (AR) and samples annealed at 400°C. Pitting in the AR sample was associated with Al–Mg–Si–Ca–O inclusions, while pitting on the samples annealed at 400°C was linked to local reduced passive film resistance. Severe cold rolling enhanced the pitting resistance of 2304 LDSS. Selective electrochemical etching revealed preferential corrosion at phase interfaces and within the austenite phase. Additionally, annealing at 500°C to 600°C led to a marked decrease in pitting resistance and increased sensitization. Electron backscatter diffraction analysis of the corroded pits in the annealed specimens indicated that pits tend to nucleate and grow in α'-martensite/austenite regions. Furthermore, the nanostructure formed during low-temperature reversion, characterized by dislocation-cell martensite with high dislocation density and stacking faults, may adversely affect corrosion resistance due to heterogeneities associated with alloying element redistribution.

36 MATERIALS SCIENCE↗

A critical review of the history of fabricating monolithic U-Mo fuel plates

The fabrication of monolithic uranium-molybdenum alloy fuels, specifically those developed for high-performance research and test reactors, began in the early 2000s. The primary fuel form consists of uranium alloyed with 10-wt% molybdenum in a thin foil coated with zirconium and encapsulated in aluminum-6061 cladding. Over the years, the process has evolved with different types of casting, heat treatments, rolling schedules, and cladding applications. This review examines the history of these fabrication processes and their impact on microstructure and fuel-swelling performance. Even though various fabrication methods were used, we found little correlation between fabrication variation and fuel swelling. This insensitive relationship between fabrication variation and fuel swelling is primarily due to inhomogeneous microstructures that formed during casting and grain refinement that occurred during rolling. We conclude that the fabrication processes we examined produced similar microstructures, indicating that the fuel microstructure is somewhat insensitive to the fabrication parameters evaluated. However, the relatively small amount of historic data, such as those for grain sizes, limited this analysis. More recently fabricated materials, such as those from ongoing irradiation experiment, Mini-Plate-1 and Mini-Plate-2, were also excluded from this analysis and are intended to be reviewed separately. The findings, that fuel microstructure is somewhat insensitive to the fabrication parameters, do not imply that any fabrication method is acceptable, given the uncertainties in data and fuel-swelling observations. For example, only arc melting and vacuum induction melting casting processes were previously explored in the historic fabrication efforts. In conclusion, the findings should not be extrapolated to other casting processes.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Integrated charging infrastructure planning and charging scheduling for battery electric bus systems

We report studies on the electric bus system planning problem have typically focused exclusively on either the deployment of charging infrastructure or the scheduling of charging events; few have examined the impact of charging facility deployment on charging activities. Considering the interdependence of system design and operational strategies, this study proposes a two-phase optimization framework for charging infrastructure planning and charging scheduling for battery electric bus systems. An integrated optimization model is first developed to simultaneously optimize charger deployment, on-board battery capacity, and charging schedules. A charging scheduling model is further proposed and a rolling horizon approach is utilized in the second phase to optimize the real-time charging scheduling of electric buses. Compared to existing electric bus system planning methods, the proposed integrated model can reduce the total system cost by 19.5%. In addition, compared to uncontrolled charging, the proposed rolling horizon-based charging strategy can reduce the total charging cost by 68.3%.

25 ENERGY STORAGE↗

Recent Progress in Developing Nb 3 Sn Conductors With Increased Specific Heat

A possible approach to reducing Nb 3 Sn magnet training is to increase the energy margin of Nb 3 Sn conductors by enhancing their specific heat (C p ). For this study, we have been developing Nb 3 Sn conductors with increased C p by incorporating substances with high C p at 2-10 K based on a conductor design that is compatible with standard Nb 3 Sn strand production. In the past couple of years our efforts have been mainly focused on improving strand design (e.g., position of high- C p filaments, thickness of the Cu tube for the high-C p filaments, ratio of the Cu powder to the high-C p substance, filament spacing, etc.) in order to obtain good strand drawability and to reduce degradation after rolling, which is needed for production of Rutherford cables. We also tried a new high-C p substance, Gd 2 O 2 S, and verified that it has much higher C p over the whole magnetic field range than the Gd 2 O 3 we used before. With that development work we can now produce high-C p strands with good drawability and low levels of degradation after rolling. This paper reports our findings and the current status of the development of high-C p Nb 3 Sn conductors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Manufacturing of Continuous Core–Shell Hydrated Salt Fibers for Room Temperature Thermal Energy Storage

The encapsulation of salt hydrate phase change materials (PCMs) in uniform microscale bodies has yet been reported in research due in part to the delicate relationship between thermal performance and water-to-salt ratios which are easily altered during manufacturing. Herein, core–shell composite fibers comprised of a salt hydrate PCM core and a poly(acrylonitrile) (PAN) shell are wet spun in a continuous process using a syringe pump and coaxial die. The PCM phase comprises calcium chloride hexahydrate (CaCl 2 ·6H 2 O) with strontium chloride hexahydrate(SrCl 2 ·6H 2 O) (3 wt%) and fumed silica(SiO 2 ) (2 wt%) as additive, a composition that is prepared from homogenous melt at 40 °C. 15 wt% PAN in dimethylsulfoxide solvent is used to prepare the shell-forming polymer gel. PCM and polymer gel injection rates of 10–40 mL h –1 are used to spin coaxial fibers through a coagulation bath, yielding continuous microtubules with diameters in the range of 850–1500 μm. Cyclic testing shows that after 1000 cycles, melting enthalpies incurred only a 3.5% decline from 131.46 to 126.9 J g –1 . In conclusion, success here overcomes several coincidental drawbacks of PCM fiber performance and manufacturing and delivers the first example of scalable roll-to-roll PCM fiber produced by wet spinning for building material applications.

36 MATERIALS SCIENCE↗

Single‐Step Recovery of Water from Stable Crude Oil‐Water Emulsion Using Surface Engineered Hybrid Inorganic‐Polymer Membranes

ABSTRACT Separating crude oil from water remains one of the most stubborn challenges in environmental remediation, especially for surfactant‐stabilized emulsions that resist conventional demulsification methods. Here, we report a scalable strategy for achieving near‐zero‐discharge separation of crude oil emulsions using a single superhydrophilic membrane. By applying low‐temperature atomic layer deposition (ALD) of various metal oxides onto activated polyvinylidene fluoride (PVDF) membranes, we create atomically precise surface‐engineered (SE) membranes that maintain an exceptionally strong hydration layer at the membrane‐feed interface, even at high oil loadings. Among the various metal oxides, TiO 2 ‐modified SE membranes exhibit superior interfacial water stability, enabling sustained dewatering of complex crude oil‐water emulsions with >98% separation efficiency and >97% water recovery, compared to only 24.6% water recovery for the pristine membrane. This separation performance surpasses conventional hydrophilic membranes and is comparable to complex Janus channel membrane systems, demonstrating near‐complete emulsion separation using a single membrane. This low‐temperature membrane surface engineering process with atomic‐level precision and potential for scalability via roll‐to‐roll fabrication is promising for industrial‐scale, energy‐efficient water treatment and oil spill remediation applications.

Sengupta, Bratin [Applied Materials Division Argon↗

Rational Regulation of Layer‐by‐Layer Processed Active Layer via Trimer‐Induced Pre‐Swelling Strategy for Efficient and Robust Thick‐Film Organic Solar Cells

Thick-film (>300 nm) organic solar cells (OSCs) have garnered intensifying attention due to their compatibility with commercial roll-to-roll printing technology for the large-scale continuous fabrication process. However, due to the uncontrollable donor/acceptor (D/A) arrangement in thick-film condition, the restricted exciton splitting and severe carrier traps significantly impede the photovoltaic performance and operability. For this work, combined with layer-by-layer deposition technology, a twisted 3D star-shaped trimer (BTT-Out) is synthesized to develop a trimer-induced pre-swelling (TIP) strategy, where the BTT-Out is incorporated into the buried D18 donor layer to enable the fabrication of thick-film OSCs. The integrated approach characterizations reveal that the exceptional configuration and spontaneous self-organization behavior of BTT-Out trimer could pre-swell the D18 network to facilitate the acceptor's infiltration and accelerate the formation of D/A interfaces. This enhancement triggers the elevated polarons formation with amplified hole-transfer kinetics, which is essential for the augmented exciton splitting efficiency. Furthermore, the regulated swelling process can initiate the favorable self-assembly of L8-BO acceptors, which would ameliorate carrier transport channels and mitigate carrier traps. As a result, the TIP-modified thin-film OSC devices achieve the champion performance of 20.3% (thin-film) and 18.8% (thick-film) with upgraded stability, among one of the highest performances reported of thick-film OSCs.

36 MATERIALS SCIENCE↗

Ultrafast (1‐5 sec) Lamination of Perovskite Solar Cells With Self‐Encapsulation Using Rapid Joule Heating

Perovskite solar cells (PSCs) are traditionally fabricated using sequential layer‐by‐layer deposition, in which each layer of the device is processed on top of the preceding layer. This constrains the processing techniques and selection of transport layer materials that can be used in the solar cell. To overcome these challenges, two half‐cells can be processed independently and then diffusion‐bonded through a lamination process. However, current lamination processes for perovskite solar cells suffer from relatively long process times, which can limit throughput when moving toward high‐volume manufacturing. In this study, a custom platform was designed for rapid‐joule heating of perovskite materials and devices. This enabled more than a 99% reduction in lamination time from 26 min to 1 s. Perovskite samples that were laminated in 1 s exhibited comparable values of percent bonded area, interfacial toughness, grain domain size, and X‐ray diffraction spectra to those laminated in greater than 10 min. As a proof‐of‐concept, 18.3% efficient devices were successfully laminated in 5 s. A transient heat transfer model was developed to describe the relationship between the perovskite temperature and the electrical power supplied to the heaters, establishing a baseline for predicting processing conditions in large‐scale manufacturing systems. Ultra‐fast lamination provides a pathway toward scalable roll‐to‐roll or sheet‐to‐sheet manufacturing of PSCs.

heat transfer↗

Enabling 6C Fast Charging of Li–Ion Batteries with Graphite/Hard Carbon Hybrid Anodes

Li-ion batteries that can simultaneously achieve high-energy density and fast charging are essential for electric vehicles. Graphite anodes enable a high-energy density, but suffer from an inhomogeneous reaction current and irreversible Li plating during fast charging. In contrast, hard carbon exhibits superior rate performance but lower energy density owing to its lower initial coulombic efficiency and higher average voltage. In this work, these tradeoffs are overcome by fabricating hybrid anodes with uniform mixtures of graphite and hard carbon, using industrially-relevant multi-layer pouch cells (>1 Ah) and electrode loadings (3 mAh cm –2 ). By controlling the graphite/hard carbon ratio, this study shows that battery performance can be systematically tuned to achieve both high-energy density and efficient fast charging. Pouch cells with optimized hybrid anodes retain 87% and 82% of their initial specific energy after 500 cycles of 4C and 6C fast-charge cycling, respectively. This is significantly higher than the 61% and 48% specific energy retention with graphite anodes under the same conditions. The enhanced performance is attributed to improved homogeneity of the reaction current throughout the hybrid anode, which is supported by continuum-scale modeling. Furthermore, this process is directly compatible with existing roll-to-roll battery manufacturing, representing a scalable pathway to fast charging.

25 ENERGY STORAGE↗

Silicon Anodes with Improved Calendar Life Enabled By Multivalent Additives

Silicon is widely recognized as the most promising upgrade for graphite anodes due to its much higher capacity, natural abundance, and ability to be directly applied in the slurry-based, roll-to-roll production lines. However, in addition to the fast capacity decay, silicon anodes also suffer from inferior calendar life in practical applications due to the unstable solid-electrode interface (SEI). Until now, strategies to effectively improve the calendar life by tailored SEIs remain largely unclear, especially in high-Si content, zero-graphite anodes. Here, silicon anodes with superior calendar life are developed by adding small concentrations of multivalent salts into the baseline electrolyte. The Ca additive reacts with the F ions in the electrolyte, forming a layer of nanocrystalline CaF 2 that is closely coated around the silicon particles. The CaF 2 -enabled new SEI is strong and dense, which effectively protects the silicon core from side reactions, leading to lower capacity decay after calendar aging at high voltage. More importantly, the Ca additive is effective universally for all available commercial silicon or SiO sources. This study provides a feasible and low-cost solution for developing silicon anodes with long calendar life, paving the way towards commercially viable silicon anodes.

25 ENERGY STORAGE↗

Controlled One‐pot Synthesis of Nickel Single Atoms Embedded in Carbon Nanotube and Graphene Supports with High Loading

Abstract Single‐atom catalysts (SACs) have attracted much attentions due to the advantages of high catalysis efficiency and selectivity. However, the controllable and efficient synthesis of SACs remains a significant challenge. Herein, we report a controlled one‐pot synthesis of nickel single atoms embedded on nitrogen‐doped carbon nanotubes (NiSA−N−CNT) and nitrogen‐doped graphene (NiSA−N−G). The formation of NiSA−N−CNT is due to the solid‐to‐solid rolling up mechanism during the high temperature pyrolysis at 800 °C from the stacked and layered Ni‐doped g‐C 3 N 4 , g‐C 3 N 4 −Ni structure to a tubular CNT structure. Addition of citric acid introduces an amorphous carbon source on the layered g‐C 3 N 4 −Ni and after annealing at the same temperature of 800 °C, instead of formation of NiSA−N−CNT, Ni single atoms embedded in planar graphene type supports, NiSA−N−G were obtained. The density functional theory (DFT) calculation indicates the introduction of amorphous carbon source substantially reduces the structure fluctuation or curvature of layered g‐C 3 N 4 ‐Ni intermediate products, thus interrupting the solid‐to‐solid rolling process and leading to the formation of planar graphene type supports for Ni single atoms. The as‐synthesized NiSA−N−G with Ni atomic loading of ∼6 wt% catalysts shows a better activity and stability for the CO 2 reduction reaction (CO 2 RR) than NiSA−N−CNT with Ni atomic loading of ∼15 wt% due to the open and exposed Ni single atom active sites in NiSA−N−G. This study demonstrates for the first time the feasibility in the control of the microstructure of carbon supports in the synthesis of SACs.

Zhao, Shiyong↗

Optimized Incorporation of Furan into Diketopyrrolopyrrole-Based Conjugated Polymers for Organic Field-Effect Transistors

Flexible electronics have received considerable attention in the past decades due to their promising application in rollable display screens, wearable devices, implantable devices, and other electronic applications. Here, in particular, conjugated polymers are favored for flexible electronics due to their mechanical flexibility and potential for solution-processed fabrication techniques, such as blade-coating, roll-to-roll printing, and high-throughput printing allowing for high-performance transistor devices. Thiophene is the prevailing conjugated unit to construct these conjugated polymers due to its favorable electronic properties. On the other hand, furans are among the few conjugated moieties that are easily derived from bio renewable resources. To promote sustainability, we selectively introduced furan into the conjugated backbone of a high-mobility polymer scaffold and systematically studied the effect on the microstructure and charge transport. We show that partially and selectively replacing thiophene units with furan can yield nearly comparable performance compared to the all-thiophene polymer. This strategy offers an improvement in the sustainability of the polymer by incorporating bio-sourced furan without sacrificing the high-performance characteristics. Meanwhile, polymers with incorrect or complete furan incorporation show reduced mobilities. This work serves to develop coherent structure–morphology–performance relationships; such knowledge will establish guidelines for the future development of sustainable, furan-based conjugated materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Manufacturing Water‐Based Low‐Tortuosity Electrodes for Fast‐Charge through Pattern Integrated Stamping

Achieving high energy density and fast charging of lithium‐ion batteries can accelerate the promotion of electric vehicles. However, the increased mass loading causes poor charge transfer, impedes the electrochemical reaction kinetics, and limits the battery charging rate. Herein, this work demonstrated a novel pattern integrated stamping process for creating channels in the electrode, which benefits ion transport and increases the rate performance of the electrode. Meanwhile, the pressure applied during the stamping process improved the contact between electrode and current collector and also enhanced the mechanical stability of the electrode. Compared to the conventional bar‐coated electrode with the same thickness of 155 μm (delivered a discharge capacity of 16 mAh g −1 at the rate of 3 C), the stamped low‐tortuosity LiFePO 4 electrode delivered 101 mAh g −1 capacity. Additionally, water was employed as a solvent in this study. Owing to its eco‐friendliness, high scalability, and minimal waste generation, this novel stamping technique inspire a new method for the industrial‐level efficient roll to roll fabrication of fast‐charge electrodes.

25 ENERGY STORAGE↗