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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

Fabrication of Solid-State Li-S Battery Components for Electric Aviation

The development of high-energy, high-safety, and high-power batteries beyond electric automobile requirements is vital for future electric aviation applications. The transition to non-volatile solid-state electrolytes (SSE) promises many advantages over traditional flammable liquid electrolytes, and may also be an enabling technology for next generation chemistries. However, significant manufacturing challenges must be overcome before the adoption of such technology. Electrolytes developed in this study were produced as sulfide-polymer composites with densified thicknesses between 20-30 microns using several processing techniques [1]. Ionic conductivity and lithium metal compatibility for the composites were compared and shown to retain reasonable ionic conductivity with improved flexibility and scalability which identifies a critical path for the production of practical solid-state batteries. Films were produced 10-15 times thinner than comparable bulk cold pressed powder electrolytes and achieved thicknesses comparable to commercial polyolefin separators (25 micron) used in commercial liquid containing lithium-ion cells. Composite conductivities were maintained above 0.2mS/cm, which holds promise for future electric aviation applications. Processing techniques are investigated to further improve electrochemical performance.

battery↗

Borate salts, polymers and composites

Described herein are borate salts useful as additives, binders, and electrolyte salts for solid state lithium ion batteries. In particular, the borate salts of Formula (I), Formula (II) and Formula (III) as described herein: can be polymerized, or can be bound to an existing polymer, to provide polymeric binders for ceramic solid state electrolytes that are themselves capable of ion transport independent of the ceramic.

Liao, Chen↗

Electrochemical-mechanical coupling failure mechanism of composite cathode in all-solid-state batteries

Composite cathode composed of active particles and solid electrolytes (SEs) can considerably enlarge the particle-SE contact areas and achieve high areal loadings in all-solid-state batteries (ASSBs). However, the challenging interfacial instability and particle damage problems remain unsolved. Herein, we establish a 3D electrochemical-mechanical coupled model to investigate the underlying failure mechanism by considering the governing electrochemical and physics processes. Micro-scale heterogeneous primary particles with random crystallographic orientation and size inside the LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111) secondary particle of the model result in the anisotropic Li diffusion and volume variation within the secondary particle, leading to significant nonuniformity of the Li concentration, and GPa-level stress distributions at primary particle boundaries, and finally causing the particle internal cracks. The particle volume shrinkage under the constraint of stiff Li 7 La 3 Zr 2 O 12 (LLZO) SE triggers the interface debonding (gap>50 nm) with increased interfacial impedance to degrade cell capacity. Higher C-rates result in larger residual stress (~100 MPa)/strain/debonding gap at dis-charging end, more likely to deteriorate the cell performance. Increasing the interfacial strength between the particle and SE can suppress the interface debonding but induces high stress (up to 10 GPa). In conclusion, results reveal the underlying mechanism of the electrochemical-mechanical coupling failure mechanism for composite cathode and provide promising guidance on the further improvement of a more robust composite cathode for ASSBs.

25 ENERGY STORAGE↗

Atmosphere revitalization for manned spacecraft - An assessment of technology readiness

The level of proficiency attained by the most effective physical and chemical regenerative processes capable of providing a habitable atmospheric environment in a spacecraft is assessed. It is shown that both the Sabatier and Bosh reactions are in a mature stage of technological readiness and can effectively reduce the carbon dioxide in a spacecraft. An electrochemical method for concentrating CO2 from an air environment offers promise to approach low levels of pCO2 control. Technological advances in the fields of solid polymer electrolytes and oxygen evolution electrocatalysts have led to a water electrolysis system that can maintain efficient performance for several years. Nitrogen supply and control of the composition of the spacecraft atmosphere is effectively provided by the circulating electrolyte technique.

Samonski, F. H., Jr.↗

Localized High-Concentration Electrolytes Get More Localized

Liquid electrolytes in batteries are typically treated as macroscopically homogeneous ionic transport media, despite having complex chemical composition and atomistic solvation structures, thus leaving a knowledge gap of microstructural characteristics. A promising electrolyte system design has recently been developed with the title of a localized high-concentration electrolyte (LHCE). These electrolytes are a summation of three components – a charge-carrying salt, a solvent that solvates the salt, and a diluent that is sparingly interactive with the salt in terms of ion solvation. This creates the perception of a high-concentration electrolyte (HCE) with high anion-cation interactions that supports a salt-derived, stable solid-electrolyte interphase, while an LHCE improves bulk electrolyte properties, such as ionic conductivity and viscosity, when compared to an HCE. Much trial by error design of this LHCE concept has been supported by simulations to confirm ionic interactions, cycling data to confirm cell stability, and post-mortem analysis to provide evidence of mechanisms. However, a systematic design to extend the capabilities of LHCEs is still to be desired. Here, we analyzed a specific LHCE mixture to dictate the best viable mixture that extends the localization of solvation structures while maintaining viable cell-level capabilities. We seek to observe and understand solvent-to-salt interactions that impact electrolyte performance. These interactions range from single-ion solvation, multidentate interactions (i.e., solvation-driven clustering), to more widespread network-level interactions. With the support of both experimental and computational analysis of different electrolyte features, we have begun a methodology of formulating the most ideal LHCE mixtures for improving the cyclability of high-capacity battery chemistries.

25 ENERGY STORAGE↗

Interconnected cathode-electrolyte double-layer enabling continuous Li-ion conduction throughout solid-state Li-S battery

All-solid-state lithium (Li) batteries with high energy density are a promising solution for the next-generation energy storage systems in large-scale devices. To simultaneously overcome the challenges of poor ionic conduction of solid electrolytes and shuttling of active materials, here we introduce a functional electrolyte-cathode bilayer framework with interconnected LLAZO channels from the electrolyte into the cathode for advanced solid-state Li-S batteries. Differing from the traditional solid-state batteries with separated layer compositions, the introduced bilayer framework provides ultrafast and continuous ion/electron conduction. Instead of transferring Li+ across the polymer and garnet phases which involve huge interfacial resistance, Li+ is directly conducted through the LLAZO channels created continuously from the cathode layer to the solid electrolyte layer, significantly shortening the diffusion distance and facilitating the redox reaction of sulfur and sulfides. A stable cycle life is demonstrated in the prototype Li-S solid-state batteries assembled with the introduced LLAZO-LLAZO@CNF interconnected bilayer framework. High capacity is obtained at room temperature, indicating the superior electrochemical properties of the bilayer framework that result from the unique design of the interconnected LLAZO garnet phase.

25 ENERGY STORAGE↗

High-Voltage Sodium–Metal Batteries with Asymmetric Fluoroalkoxylated Organoborate Anion Chemistry

The high reactivity of sodium (Na) metal restricts its compatibility to ether-based electrolytes, while the poor oxidative stability of ethers precludes their coupling to high-voltage cathodes, fundamentally limiting the operating voltage and energy density of sodium–metal batteries (SMBs). We present here a coordination-asymmetry strategy to reconcile this thermodynamic mismatch by generating in situ an asymmetric fluoroalkoxylated organoborate anion, [FB(OCH(CF 3 ) 2 ) 3 ] − (BOF – ), via a Lewis acid–base adduct reaction in ether electrolyte. The asymmetric ligand architecture differentiates oxidative and fluorination pathways: oxidizable B–O moieties mediate controlled interfacial reconstruction, whereas the terminal B–F units supply fluorine for chemical passivation. This self-adaptive chemistry yields nanoscale, conformal, compositionally graded interphases: a boron-oxide/boron-oxycarbide-rich cathode-electrolyte interphase (CEI) that mitigates ether oxidation and a bilayered inorganic–organic solid–electrolyte interphase (SEI) that regulates Na deposition. The nanostructured interphases enable highly reversible Na plating/stripping with an average Coulombic efficiency (CE) of 99.98% and sustain stable 4.3 V operation of anode-free SMBs in oxidation-prone ether electrolytes. Furthermore, this work establishes asymmetric boron coordination as a molecular-level design principle for creating chemically adaptive interphases that overcome the redox asymmetry in energy-dense electrochemical systems.

Anions↗

Stabilizing lithium-metal electrodes with polymer coatings

Increasing the energy density of batteries can accelerate the deployment of electric vehicles, expand the utilization of renewable energy and, in turn, reduce greenhouse gas emissions. Different from commercially available lithium-ion batteries, high-energy-density lithium-metal batteries use metallic lithium instead of graphite as the negative electrode. Furthermore, the commercialization of lithium-metal batteries is hindered by the electrochemical instability of lithium metal. Polymer coatings have shown promise in addressing issues related to each step of heterogeneous lithium deposition. Here we summarize the current understanding of key design principles and highlight relevant coating compositions. Moreover, we discuss high-performing coating–electrolyte pairs and provide an outlook on interface design for novel electrolytes.

Batteries↗

Garnet/PVDF-HFP Hybrid Membranes for Li-Metal Batteries: Cooperative Research and Development Final Report, CRADA Number CRD-19-00807

Hazen Research, Inc., in collaboration with University of Colorado, Boulder (CU-B) and National Renewable Energy Laboratory (NREL), will develop and demonstrate a ceramic-polymer hybrid membrane based on garnet (Li7La3Zr2O12) and PVDF (Poly Vinylidene Fluoride)-HFP (Hexafluoropropylene) adaptable to Li-metal anodes. Under this CRADA, NREL will test the developed membranes providing feedback and advice to demonstrate hybrid membranes with Li-ion conductivity >10-4 S/cm at room temperature that are stable with Li-metal, followed by demonstration of full cells with Li-metal anode.

33 ADVANCED PROPULSION SYSTEMS↗

Experiments in corrosion for younger students by and for older students

The objectives are to illustrate the electrochemical nature of corrosion and to observe the location of anodes and cathodes (arising from differences in composition and cold work) of metals immersed in electrolyte solutions. The magnitudes of voltages and current densities on corroding couples is obtained.

Masi, James V.↗

Carbon Materials Embedded with Metal Nanoparticles as Anode in Lithium-Ion Batteries

Carbon materials containing metal nanoparticles that can form an alloy with lithium were tested for their capacity and cycle life to store and release lithium electrochemically. Metal nanoparticles may provide the additional lithium storage capacity as well as additional channels to conduct lithium in carbon. The cycle life of this carbon-metal composite can be long because the solid-electrolyte interface (SEI) on the carbon surface may protect both lithium and the metal particles in the carbon interior. In addition, the voids in the carbon interior may accommodate the nanoparticle's volume change, and such volume change may not cause much internal stress due to small sizes of the nanoparticles. This concept of improving carbon's performance to store and release lithium was demonstrated using experimental cells of C(Pd)/0.5M Lil-50/50 (vol.%) EC and DMC/Li, where C(Pd) was graphitized carbon fibers containing palladium nanoparticles, EC was ethylene carbonate, and DMC was dimethyl carbonate. However, such improvement was not observed if the Pd nanoparticles are replaced by aluminum, possibly because the aluminum nanoparticles were oxidized in air during storage, resulting in an inert oxide of aluminum. Further studies are needed to use this concept for practical applications.

Hung, Ching-cheh↗

Development of Chemically and Thermally Robust Lithium Fast Ion Conducting Chalcogenide Glasses

In this project, a new research thrust into the development of an entirely new class of FIC glasses has begun that may lead to a new set of optimized thin-film lithium ion conducting materials. New chemically robust FIC glasses are being prepared that are expected to exhibit unusually high chemical and electrochemical stability. New thermally robust FIC glasses are being prepared that exhibit softening points in excess of 500 C which will dramatically expand the usable operating temperature range of batteries, fuel-cells, and sensors using such electrolytes. Glasses are being explored in the general compositional series xLi2S+ yGa2S3 + (1-x-y)GeS2. Li2S is added as the source of the conductive lithium ions. GeS2 is the base glass-forming phase and the trivalent sulfides, Ga2S3, is added to increase the "refractoniness" of the glass, that is to significantly increase the softening point of the glass as well as its chemical stability. By optimizing the composition of the glass, new glasses and glass-ceramic FIC materials have been prepared with softening points in excess of 500 C and conductivities above 10(exp -3)/Ohm cm at room temperature. These latter attributes are currently not available in any FIC glasses to date.

Martin, Steve W.↗

Evaluation of Electrochemical Methods for Electrolyte Characterization

This report documents summer research efforts in an attempt to develop an electrochemical method of characterizing electrolytes. The ultimate objective of the characterization would be to determine the composition and corrosivity of Martian soil. Results are presented using potentiodynamic scans, Tafel extrapolations, and resistivity tests in a variety of water-based electrolytes.

Heidersbach, Robert H.↗

Improved Anode for a Direct Methanol Fuel Cell

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the catalyst by increasing electrical connectivity between catalyst particles. However, the relatively low density of carbon results in thick catalyst layers that impede the mass transport of methanol to the catalytic sites. Also, the electrical conductivity of carbon is less than 1/300th of typical metals. Furthermore, the polymer-electrolyte membrane material is acidic and most metals are not chemically stable in contact with it. Finally, a material that conducts electrons (but not protons) does not contribute to the needed transport of protons produced in the electro-oxidation reaction.

Valdez, Thomas↗

Nanopore Confinement of C-H-O Mixed-Volatile Fluids Relevant to Subsurface Energy Systems

The overarching goal of OU’s contribution to the project was to use novel computational approaches to quantify the effect of variable nanopore features (pore size, volume, topology, and chemistry) and the presence of water or salt solutions on the sorption and transport of carbon-bearing fluids. To achieve this goal OU collaborators tested test two related hypotheses: • The transport of water and aqueous electrolytes in nanopores is controlled by pore size, pore wall composition, and the type of salt – structure-maker (e.g., CaCl 2 ) versus structure-breaker (e.g., NaCl) that affect the hydrogen-bonding network. • The structure, solubility, and transport of carbon-bearing molecules in water or aqueous electrolyte-filled nanopores are controlled by the substrate type including degree of hydration, and pore features, and regulated by the hydration structure of the guest molecules.

58 GEOSCIENCES↗

Achieving stable all-solid-state lithium-metal batteries by tuning the cathode-electrolyte interface and ionic/electronic transport within the cathode

All-solid-state batteries with sulfide electrolytes and high-nickel layered oxide cathodes attract much interest due to their high specific energy. However, their cycling performance is primarily influenced by the interface between the sulfide electrolyte and the high-Ni layered oxide particles, which requires the use of composite cathodes with high ionic and electronic conductivities to achieve a kinetically stable interface inside the cathode. Here, we apply Ti 2 O 3 particles to the high-Ni cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), where Ti 2 O 3 not only acts as an electronic conductor to provide a fast diffusion path for electrons in the composite cathode, but also absorbs the lattice oxygen released from NCM811 cathode during cycling, stabilizing the Li 6 PS 5 Cl/NCM811 interface and suppressing electrolyte oxidation. The as-modified cathode exhibits an initial specific capacity of 192 mAh g -1 and retains 166 mAh g -1 after 140 cycles at 0.1C rate with a good capacity retention of 86.5%. Furthermore, the composite cathode displays high rate capability even at 1C rate. By contrast, the unmodified Li 6 PS 5 Cl/NCM811 cathode shows poor cycling performance with only 130 mAh g -1 remaining after 130 cycles. This work provides a new direction for the design of cathodes for all-solid-state batteries that can deliver high specific energy with long cycle life.

25 ENERGY STORAGE↗

Temperature responses of exercizing dogs to infusion of electrolytes

The effect of infusions with solutions of various ionic and osmotic composition on exercise temperature responses was studied in dogs who do not regulate their temperature by sweating. The results suggest an association between plasma Na+ and Ca++ level within the normal physiological range and the control of body temperature during exercise.

Greenleaf, J. E.↗

Comparative Study of Vinylene Carbonate and Lithium Difluoro(oxalate)borate Additives in a SiO x /Graphite Anode Lithium-Ion Battery in the Presence of Fluoroethylene Carbonate

The SiO x /graphite composite is recognized as a promising anode material for lithium-ion batteries (LIBs), owing to the high theoretical capacity of SiO x combined with the excellent stability of graphite. However, the inherent disadvantage of volume expansion in silicon-based anodes places significant challenges on the solid electrolyte interphase (SEI) and severely degrades the electrochemical performance. Rational formulation of electrolyte, including its additives, is crucial in accommodating and optimizing the composition of the SEI and enhancing the cell performance. In this work, we present a comparative study of vinylene carbonate (VC) and lithium difluoro(oxalate)borate (LiDFOB) additives combined with fluoroethylene carbonate (FEC) in the electrolyte for SiO x /graphite∥LiNi 1–x–y–z Co x Mn y Al z O 2 full cells. VC outperformed LiDFOB as an additive, delivering higher capacity cycling, higher Coulombic efficiency, and better cycle stability up to 400 cycles. XPS and impedance analyses reveal that LiDFOB contributed to SEI/CEI with both a lower proportion of LiF and a higher proportion of poly(VC), which tended to produce higher cell impedance. XRD and XANES further indicated that using the LiDFOB additive, the NCMA cycled to a shallower degree than that of the VC additive. Although the VC additive maintained a higher capacity up to 400 cycles, microstrain and SEM analyses show a higher strained NCMA along with clear evidence of cracking over the surface of the NCMA particle in VC-based electrolyte but not in LiDFOB. In conclusion, this suggests that the negative influence of LiDFOB at the anode (inferior SEI) supersedes the negative impact of both a cracked NCMA and a deeper cycled NCMA and SiO x -based anode.

36 MATERIALS SCIENCE↗