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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Solvent‐Free Self‐Assembly for Scalable Preparation of Highly Crystalline Mesoporous Metal Oxides

Abstract Mesoporous metal oxides (MMOs) have been demonstrated great potential in various applications. Up to now, the direct synthesis of MMOs is still limited to the solvent induced inorganic‐organic self‐assembly process. Here, we develop a facile, general, and high throughput solvent‐free self‐assembly strategy to synthesize a series of MMOs including single‐component MMOs and multi‐component MMOs (e.g., doped MMOs, composite MMOs, and polymetallic oxide) with high crystallinity and remarkable porous properties by grinding and heating raw materials. Compared with the traditional solution self‐assembly process, the avoidance of solvents in this method not only greatly increases the yield of target products and synthesis efficiency, but also reduces the environmental pollution and the consumption of cost and energy. We believe the presented approach will pave a new avenue for scalable production of advanced mesoporous materials for various applications.

Xiong, Hailong↗
DOE OSTI2023

Solvent‐free Synthesis of Multi‐Module Pore‐Space‐Partitioned Metal‐Organic Frameworks for Gas Separation

Abstract Multi‐module design of framework materials with multiple distinct building blocks has attracted much attention because such materials are more amenable to compositional and geometrical tuning and thus offer more opportunities for property optimization. Few examples are known that use environmentally friendly and cost‐effective solvent‐free method to synthesize such materials. Here, we report the use of solvent‐free method (also modulator‐free) to synthesize a series of multi‐module MOFs with high stability and separation property for C 2 H 2 /CO 2 . The synthesis only requires simple mixing of reactants and short reaction time (2 h). Highly porous and stable materials can be made without any post‐synthetic activation. The success of solvent‐free synthesis of multi‐module MOFs reflects the synergy between different modules, resulting in stable pore‐partitioned materials, despite the fact that other competitive crystallization pathways with simpler framework compositions also exist.

Xiao, Yuchen↗
DOE OSTI2023

Electron Delocalization Enables Sulfone-based Single-solvent Electrolyte for Lithium Metal Batteries

Li-metal batteries (LMB), although providing high energy density, face the grand challenge of identifying good electrolyte solvents for cycling. Common solvents are either only stable against lithium metal anode or only stable against LiNi x MnyCo 1-x-y O 2 (NMC) cathode. There is significant effort trying to increase the cathode stability for ether electrolytes, which are in general stable against lithium metal anode. In comparison, there is much less effort trying to increase the anode stability of electrolytes that are stable against NMC cathode. One example is the sulfone-based electrolyte. It has good cathode stability but is hindered from practical application because of (1) high viscosity and poor wetting capability and (2) poor anode stability. Here, we solve these issues by modifying the sulfone molecules using resonance and electron withdrawing effect. The viscosity is significantly reduced by delocalizing the electrons through introducing additional oxygen on the molecular backbone and applying appropriate fluorination. The resulting molecule 2,2,2-trifluoroethyl mesylate (TFEM) has decreased Lewis basicity and less reactivity toward Li + . In conclusion, the electrolyte based on TFEM as single solvent enables cycling of LMB under harsh conditions of low N/P ratio (21 mg/cm 2 NMC811 and 50 μm Li) with 90 % capacity retention after 160 cycles at C/3 discharge rate.

25 ENERGY STORAGE↗
DOE OSTI2023

Electron Delocalization Enables Sulfone-based Single-solvent Electrolyte for Lithium Metal Batteries

Li-metal batteries (LMB), although providing high energy density, face the grand challenge of identifying good electrolyte solvents for cycling. Common solvents are either only stable against lithium metal anode or only stable against LiNi x Mn y Co 1-x-y O 2 (NMC) cathode. There is significant effort trying to increase the cathode stability for ether electrolytes, which are in general stable against lithium metal anode. In comparison, there is much less effort trying to increase the anode stability of electrolytes that are stable against NMC cathode. One example is the sulfone-based electrolyte. It has good cathode stability but is hindered from practical application because of (1) high viscosity and poor wetting capability and (2) poor anode stability. Here, we solve these issues by modifying the sulfone molecules using resonance and electron withdrawing effect. The viscosity is significantly reduced by delocalizing the electrons through introducing additional oxygen on the molecular backbone and applying appropriate fluorination. The resulting molecule 2,2,2-trifluoroethyl mesylate (TFEM) has decreased Lewis basicity and less reactivity toward Li + . The electrolyte based on TFEM as single solvent enables cycling of LMB under harsh conditions of low N/P ratio (21 mg/cm 2 NMC811 and 50 μm Li) with 90 % capacity retention after 160 cycles at C/3 discharge rate.

25 ENERGY STORAGE↗
DOE OSTI2026

Tuning the Mechanical Properties of Crosslinked Copolymers via Sequence and Solvent‐Selective Swelling for Vat Photopolymerization

Block copolymers (BCPs) offer distinct advantages for vat photopolymerization by enabling mechanically programmable network structures through microphase-separated morphologies that can be kinetically trapped during curing, yielding properties unattainable in homogeneous resins. However, the respective roles of repeat-unit sequence and solvent environment, together with their interplay in directing network formation and mechanical performance, remain unclear. Here, we synthesize a series of CO 2 -based polycarbonate copolymers comprising a crosslinkable glassy poly(vinyl cyclohexene carbonate) (PVCHC, A block) and a non-crosslinkable soft poly(propylene carbonate) (PPC, B block). The polymer sequence is systematically varied (ABA, BAB, and statistical), and solvent choice controls block-selective swelling to jointly control gelation behavior, microphase morphology, and mechanical response through changes in the accessibility and local environment of photocrosslinkable vinyl groups during network formation, as revealed by photorheology and small angle x-ray scattering. By tuning polymer sequence and curing solvent, we transform nominally identical formulations from brittle to highly ductile materials, achieving a three-orders-of-magnitude range in toughness (0.003 to 9.1 MJ m −3 ). These results establish clear structure–processing–property relationships and identify polymer sequence and selective solvation as powerful strategies for programming both printability and performance of block copolymer resins for additive manufacturing.

additive manufacturing↗
DOE OSTI2020

Fractionating and Purifying Softwood Kraft Lignin with Aqueous Renewable Solvents: Liquid–Liquid Equilibrium for the Lignin–Ethanol–Water System

Hot ethanol–water solutions can be used to simultaneously fractionate and purify softwood Kraft lignin through the Aqueous Lignin Purification with Hot Agents (ALPHA) process, using the regions of liquid–liquid equilibrium (LLE) that form at selected temperatures and solvent-to-lignin feed (S/F) ratios. Lignin, ethanol, and water compositions are measured for the solvent-rich (SR) and lignin-rich (LR) liquid phases in mutual equilibrium, as well as the lignin and metals mass distributions between the two phases. As depicted in quasi-ternary diagrams for clarity, both temperature and S/F ratio can be used to grow, merge, and even split the regions of LLE, giving significant control over both molecular weight (MW) and lignin purity. For example, a solvent comprising 45:55 EtOH/H 2 O at 75 °C and an S/F ratio of 6:1 enables recovery of an ultrapure (95 % of Na removed), higher MW (M n =8400 Da) lignin fraction in the LR phase. On the other hand, 95:5 EtOH/H 2 O at 45 °C and S/F=3:1 enables recovery of an ultrapure, low MW (1500 Da) lignin in the SR phase.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The Relationship Between Catalyst and Solvent in Hydrogenation via Condensed Phase Heterogeneous Catalysis

To understand a system is to understand its components and their sum. Cascading interactions between catalyst, solvent, and reagent create a complex web of influences when heterogeneous catalysis meets the condensed phase. Due to the importance of heterogeneous catalysis in chemical manufacturing, and the present and growing potential of condensed phase chemistries, the understanding of these interactions is of paramount importance. To develop condensed phase heterogeneous catalysis, the field needs to develop understanding of the role of solvent in heterogeneous catalytic hydrogenation. While no small feat, fields such as biofuel and petroleum refining have established certain applicable generalities that can bridge the knowledge gap in emerging technologies such as integrated carbon capture and conversion to materials (IC 3 M). In this review, we thoughtfully probe the current paradigm of condensed phase catalysis by challenging the idea that catalyst and solvent are independent reaction design choices. Challenges such as lack of experimental stability studies and poor resolution on our conceptualization of the condensed phase environment are discussed. Parameters such as viscosity and the dielectric constant, and their role on reaction activity and stability are explored. Knowledge gained from established biomass and petroleum processes is discussed and used to anticipate behavior in novel processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

A Solubility Comparison of Cyclotetramethylenetetranitramine (HMX) and Potential Mock-HMX Candidates in Solvents Relevant to Slurry Formulating Polymer-Bonded Materials

Understanding solubility behavior of organic crystalline materials is critical in the development of slurry-formulated plastic bonded composites. In the field of high explosives (HE), a common method for obtaining high density, greater than 95 % theoretical maximum density, is to encapsulate HE in a polymer matrix resulting in the formation of plastic bonded explosive (PBX) prills. Prill formation is highly nuanced and requires understanding of particle size distributions, solvent, antisolvent, and binder system as well as interactions thereof. In this paper, in an effort to create mock-HE that mimics HE in density and mechanical strength, solubility of candidate molecules was compared to cyclotetramethylenetetranitramine (HMX) in binder solvents relevant to prill formation. The results indicate that the mock candidates chosen for this study have different solubilities compared to HMX in water and both organic solvents, 2-butanone and ethyl acetate, investigated. With these solubility differences known, prills to match PBXs based on HMX can be formulated, pressed and tested.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Effects of solvent formulations in electrolytes on fast charging of Li-ion cells

Improving the fast charging performance of lithium ion batteries (LIBs) has the promise to increase the widespread adoption of electric vehicles (EVs). Electrolyte development plays an important role in enabling fast charging. In this study, fast charging performance of LIBs is studied with different electrolytes of 1.2 M LiPF 6 in Ethylene Carbonate (EC)/Ethyl Methyl Carbonate (EMC)/co-solvents at 30/50/20 wt%. The co-solvents are methyl acetate (MA), ethyl acetate (EA), ethyl formate (EF), dimethyl carbonate (DMC) and EMC. Long term cycling performance under fast charging shows different capacity retention behaviors for different co-solvents. The structural changes in the electrode material are studied by X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD). The molarity changes in electrolyte is investigated by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The electrode/electrolyte interfaces before and after fast charging are analyzed by X-ray photoemission spectroscopy (XPS). The characterization results are in good agreement with the long-term cycling performance. DMC shows the highest fast-charging capability among the five studied co-solvents due to its increased conductivity, improved electrode/electrolyte interface and stable electrode structural integrity.

25 ENERGY STORAGE↗
DOE OSTI2022

Solute- and solvent-based electromotive force cells for activity measurements of electroactive species in molten salts

A novel combination of solute- and solvent-based electrodes was used to determine the activities of NdCl 3 and GdCl 3 in molten LiCI-KCI eutectic using electromotive force measurements across a broad concentration range of dissolved electroactive species. First, an electrochemical cell using solute-based electrodes was used to define the relative activity of each species as a function of concentration and the concentration region in which Henry's law was applicable. Next, the electromotive force between a solute-based electrode with a known NdCl 3 or GdCl 3 concentration and a solvent-based electrode with a known electromotive force was measured. The solvent-based electrode potential was converted to the Lithium Eutectic Electrode (LEE) potential, which allowed the activity of dissolved NdCl 3 and GdCl 3 to be calculated at the concentrations measured using the solute-based electrodes. The described two-cell method uses electromotive force measurements to accurately determine the activity of electroactive species over a wide concentration range and provides a simple approach to closing the knowledge gap of thermochemical properties of molten salts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Networks of electrochemical oxidation of common lithium-ion Battery solvents revealed by NMR spectroscopy

Raising the upper cutoff voltage of lithium-ion batteries (LIBs) to increase energy density often exceeds the electrolyte’s anodic stability limit, accelerating degradation and creating a major durability tradeoff. Designing electrolytes that can sustain long-term high-voltage cycling requires a clearer understanding of the fundamental mechanisms occurring when commercial carbonate solvents oxidize. Here, to this end, simplified single-salt, single-solvent formulations of LiClO 4 and LiPF 6 in dimethyl carbonate (DMC), ethylene carbonate (EC), or ethyl methyl carbonate (EMC) were anodically electrolyzed on inert electrodes and monitored for extended periods of time using 1 H, 13 C, 19 F, and 35 Cl nuclear magnetic resonance (NMR) spectroscopy. The controlled environment of the experiments, coupled to the unique sensitivity of NMR, unveiled novel metastable intermediates and the formation of branching networks of products with temporal evolution. Oxidation of the pristine solvent primarily proceeds through a radical pathway that also produces highly reactive protons but faces competition from a second pathway involving a radical carbocation intermediate. In all cases, the intermediates follow a variety of downstream pathways that can intersect with each other. The concomitant network of reactions represents a significant increase in complexity compared to common descriptions in the literature, yet, critically, it helps explain the wide range of products typically identified in electrolyte oxidation in complete cells. The results highlight the need for refocusing fundamental research on anodic stability to analysis of the hierarchy of reaction networks to better inform efforts to mitigate the detrimental effects on battery performance, including prevention and harvesting of proton and radical products.

Electrolytes↗
DOE OSTI2020

Lignin extraction and upgrading using deep eutectic solvents

Deep eutectic solvents (DESs) are a class of green solvents exhibiting low vapor pressure, high thermal stability,low toxicity, and biodegradability. These features make them attractive solvents for lignocellulosic biomassprocessing, especially for lignin valorization. DESs not only solubilize lignin from lignocellulose biomass, butalso confer extracted lignin with properties favorable to its further upgrading. This review summarizes recentadvances in biomass fractionation using DESs for lignin extraction. It also covers lignin upgrading in DESs interms of depolymerization and functionalization. The challenges of tailoring lignin properties by DESs for differentvalorization routes are also discussed.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

The effect of moisture on hydrocarbon-based solvent liquefaction of pine, cellulose and lignin

In this report we examined the effect of moisture on the solvent liquefaction of loblolly pine, cellulose, and lignin in tetralin at 280 °C and pressures ranging from 15 to 70 bar. Solvent liquefaction experiments were conducted in a quasi-batch reactor capable of continuous pressure control and external vapor condensation. Moisture was varied by the controlled addition of de-ionized water. Control over the system pressure subsequently impacted the removal of water vapor from the reactor. Liquid yield decreased by 25, 21, and 35 wt%, for pine, cellulose, and lignin, respectively, when moisture content was increased from 1 to 50 wt% at 42 bar. Humins were observed in the solid residue from liquefaction of wet cellulose. Wet lignin yielded a substantial amount of solid residue compared to dry lignin with a corresponding decrease in total phenolic monomer production. It was concluded that the ionic dissociation of water was an important factor in loss of liquid yield in the presence of water. Although water was less than 20 wt% of the solvent loading in these experiments, it strongly influenced the liquefaction of biomass and biomass components.

09 BIOMASS FUELS↗
DOE OSTI2020

Fluorinated co-solvent promises Li-S batteries under lean-electrolyte conditions

Practical lithium-sulfur batteries stipulate the use of a lean-electrolyte and a high Coulombic efficiency of the lithium metal anode. In this work, we employ 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether as a co-solvent in the electrolyte of Li-S batteries to meet the demands. The co-solvent fosters the formation of a LiF-rich solid electrolyte interphase on lithium metal anode, as revealed by Ab initio molecular dynamics and Femtosecond Stimulated Raman spectroscopy. The co-solvent results in an average Coulombic efficiency of 99.4% for lithium plating/stripping cycles. Full cells with a capacity ratio of 2 between lithium anode and the S@PAN cathode (3 gs cm –2 ) exhibited a stable cycle life over 100 cycles at an electrolyte/sulfur ratio of 2 µL mg –1 , validating the high Coulombic efficiency of the lithium anode and demonstrating the compatibility of the electrolyte with both electrodes. To enhance the energy density, we prepared a hybrid cathode composed of 45 wt.% VS 2 mixed with ZnS-coated Li 2 S@graphene as the cathode. Based on the mass of both electrodes and the electrolyte, the full cell delivers an energy density of 483 Wh kg –1 , which demonstrates viable Li-S batteries with the lean-electrolyte.

25 ENERGY STORAGE↗
DOE OSTI2026

Delamination recycling of multilayer plastic films: Solvent-assisted separation pathways and recovery of solid polyolefins

Multilayer plastic films are excellent packaging materials due to the bound layers of multiple polymers, with each different polymer contributing to the film properties. Desirable properties lead to continuously growing demand for multilayer films. Multilayer plastic films are typically single-use and, as such, their increased production and disposal have led to waste management problems. Multilayer films are not currently recyclable primarily due to the multiple bound polymers. This work advances delamination as a recycling process to separate and sequester valuable polymers from multilayer films, facilitating the incorporation of these polymers into the circular economy. We effect delamination in a physical process that preserves targeted polymers as solid film, hence retaining their embodied energy. This work documents three different pathways of inducing delamination of multilayer films, with appropriate solvents disrupting adhesion between adjacent layers or dissolving a minor component of the film in less than an hour and at temperatures below 90°C, and where all initial polyethylene is maintained in its solid form throughout the process and is recovered at high purity. Solvent-based delamination is exemplified on commercial multilayer films with majority polyethylene (PE), and polyethylene terephthalate (PET) or ethylene vinyl alcohol copolymer (EVOH) or nylon also present. Solvent-based delamination is an energy-efficient and environmentally friendly recycling process that improves upon dissolution-precipitation recycling, since delamination involves very little dissolution and no precipitation, and is superior to pyrolysis which breaks down the polymers, while delamination keeps polymer chains intact. Furthermore, delamination recycling can contribute to the sustainable use of multilayer films as they continue to protect our food and medicine.

Chemical Recycling↗
DOE OSTI2024

Innovative biphasic solvent systems for lignocellulosic biorefinery

Bioconversion of lignocellulosics to ethanol is significantly hindered by biomass recalcitrance and, therefore, often requires a biomass pretreatment step. Furan-based compounds such as furfural (FF) and 5-hydroxymethylfurfural (HMF) are versatile building blocks for fuels and chemicals. However, their production during pretreatment often suffers from low yield and low separation efficiency. Biphasic solvent systems are capable of reducing biomass recalcitrance and extracting furans into the organic phase, thus preventing their degradation, increasing their yield, and allowing much easier separation. The development of a sustainable biphasic solvent system is essential to the furan-driven biorefinery and has drawn significant attention. Finally, this review systematically summarizes recent advances in the development of biphasic solvent systems in lignocellulosic biorefinery for improving the production of liquid fuels and furan-based compounds.

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

Direct Air Capture Using Aqueous Amino Acid Solvents in a Crossflow Absorber

Carbon dioxide (CO 2 ) is the most abundant of all greenhouse gases (GHGs). CO 2 levels in the atmosphere are 50% higher than in the preindustrial era, trapping heat. CO 2 removal from the atmosphere by direct air capture (DAC) is needed to achieve the internationally agreed global temperature goals. The most common CO 2 capture technology is absorption by aminebased solvents in packed columns. Amino acid solutions have recently gained attention due to their advantages over traditional amine solvents. To be implemented effectively, DAC industrial processes need to handle large airflow rates in separation absorbers. The large air and solvent flow rates preclude the use of countercurrent columns due to high-pressure drops and the occurrence of flooding. Crossflow air−liquid absorbers are used to handle large air and liquid volumes due to their lower-pressure drop. The objective of this work is to study the influence of crossflow absorber geometric parameters and operating conditions on product formation and process efficiency. An already derived theoretical model for countercurrent absorbers has been modified to simulate the operation of a crossflow DAC absorber. The predictive model was implemented into a computer code that was used to study the efficiency of the processes as geometric equipment dimensions and operating parameters vary. Practical suggestions are made to design more efficient DAC processes.

Absorption↗
DOE OSTI2026

Impact of Small-Alkane Solvents on Polyolefin Hydrogenolysis over a Ruthenium Catalyst

Selective catalytic hydrogenolysis of polyolefins is a promising route to convert plastic waste into valuable liquid products, such as lubricants, waxes, and surfactants. However, the high viscosity of polymer melts imposes mass transfer limitations on this reaction. Solvents can mitigate these challenges, but their effects on reaction kinetics and product selectivity remain underexplored. Here, we systematically explore the effects of small n-alkanes and cycloalkanes on the hydrogenolysis of polyethylene and polypropylene over a Ru/TiO 2 catalyst. Using kinetic measurements and isotopic labeling, we show that n-octane at high mass fractions alters the mechanism from direct hydrogenation to solvent-mediated hydrogen transfer, reducing the rate of C–C bond cleavage. Longer alkanes further inhibit reactivity due to stronger surface binding. 1,4-Dimethylcyclohexane suppresses methane formation, favoring heavier products, while decalin likely forms surface-bound aromatics that poison the catalyst. Overall, alkane solvents modulate product selectivity and reduce the yield of methane byproduct, allowing for ∼35–40% selectivity to valuable C 20 -C 30 alkane products. This work highlights the complex impact of polymer–alkane mixtures on hydrogenolysis kinetics relevant to the design of commercial-scale plastic waste valorization processes.

Catalysts↗