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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Thin coatings for protecting titanium aluminides in high-temperature oxidizing environments

Titanium aluminides have high specific strengths at high temperatures but are susceptible to environmental attack. Their use in many aerospace applications would require that they be protected with coatings that, for structural efficiency, must be thin. It is conceivable that acceptable coatings might be found in several oxide systems, and consequently, oxide coatings of many compositions were prepared from sol-gels for study. Response-surface methodology was used to refine coating compositions and factorial experiments were used to develop coating strategies. Oxygen permeability diagrams of two-layer coatings for several oxide systems, an analysis of multiple-layer coatings on rough and polished surfaces, and modeling of the oxidation weight gain are presented.

Wiedemann, K. E.↗
NASA NTRS1992

Progress report

The NASA funding allowed Clark Atlanta University (CAU) to establish a High Performance Polymers And Ceramics (HiPPAC) Research Center. The HiPPAC Center is consolidating and expanding the existing polymer and ceramic research capabilities at CAU through the development of interdepartmental and interinstitutional research in: (1) polymer synthesis; (2) polymer characterization and properties; (3) polymer processing; (4) polymer-based ceramic synthesis; and (5) ceramic characterization and properties. This Center has developed strong interactions between scientists and materials scientists of CAU and their counterparts from sister institutions in the Atlanta University Center (AUC) and the Georgia Institute of Technology. As a component of the center, we have started to develop strong collaborations with scientists from other universities and the HBCU's, national and federal agency laboratories, and the private sector during this first year. During this first year we have refined the focus of the research in the HiPPAC Center to three areas with seven working groups that will start programmatic activities on January 1, 1993, as follows: (1) nonlinear optical properties of chitosan derivatives; (2) polymeric electronic materials; (3) nondestructive characterization and prediction of polyimide performance; (4) solution processing of high-performance materials; (5) processable polyimides for composite applications; (6) sol-gel based ceramic materials processing; and (7) synthetic based processing of pre-ceramic polymers.

Abhiraman, A.↗
NASA NTRS1994

Synthesis and characterization of advanced materials for Navy applications

The synthesis of ceramics and ceramic coatings through the sol-gel process has extensive application with the United States Navy and a broad range of potential commercial applications as well. This paper surveys seven specific applications for which the Navy is investigating these advanced materials. For each area, the synthetic process is described and the characteristics of the materials are discussed.

Covino, J.↗
NASA NTRS1996

Nanoparticulate gellants for metallized gelled liquid hydrogen with aluminum

Gelled liquid hydrogen was experimentally formulated using sol-gel technology. As a follow-on to work with cryogenic simulants, hydrogen was gelled with an alkoxide material: BTMSE. Initial results demonstrated that gellants with a specific surface area of 1000 m(exp 2)/g could be repeatably fabricated. Gelled hexane and metallized gelled hexane (with 13.8-wt% Al) were produced. Propellant settling testing was conducted for acceleration levels of 2 to 10 times normal gravity and a minimum gellant percentage was determined for stable gelled hexane and metalized gelled hexane. A cryogenic capillary rheometer was also designed, constructed, and used to determine the viscosity of gelled hydrogen. Small volumes of liquid hydrogen were gelled with a 7- to 8-wt% gellant level. The gelled H2 viscosity was 1.5 to 3.7 times that of liquid hydrogen: 0.048 to 0.116 mPa-s versus 0.03 mPa-s for liquid H2 (at 16 K and approximately 1 atm pressure).

Palaszewski, Bryan↗
NASA NTRS1996

Space Electrochemical Research and Technology

Individual papers presented at the conference address the following topics: development of a micro-fiber nickel electrode for nickel-hydrogen cell, high performance nickel electrodes for space power application, bending properties of nickel electrodes for nickel-hydrogen batteries, effect of KOH concentration and anions on the performance of a Ni-H2 battery positive plate, advanced dependent pressure vessel nickel hydrogen spacecraft cell and battery design, electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery design, a novel unitized regenerative proton exchange membrane fuel cell, fuel cell systems for first lunar outpost - reactant storage options, the TMI regenerable solid oxide fuel cell, engineering development program of a closed aluminum-oxygen semi-cell system for an unmanned underwater vehicle, SPE OBOGS on-board oxygen generating system, hermetically sealed aluminum electrolytic capacitor, sol-gel technology and advanced electrochemical energy storage materials, development of electrochemical supercapacitors for EMA applications, and high energy density electrolytic capacitor.

Richard M Wilson↗
NASA NTRS1996

Enhancing Adhesion: Relative Merits of Different Approaches

Adhesive performance is improved mainly by manipulation of the bimaterials interface zone, which is only a few molecules thick. There are three approaches to enhancement of interfacial adhesion at the molecular level. They are 1) changing the nonchemically bonded interactions across the interface from weak ones to strong ones, 2) making the true interfacial area much larger than the simple geometric area, and 3) inducing chemical bonding between the two materials forming the interface. Our goal this summer was to question some of the built-in assumptions contained within these approaches and to determine the most promising approach, both theoretically and practically, for enhancing adhesion in NASA structures. Our computations revealed that all three of these approaches have, in theory, the potential to enhance molecular adhesion approximately ten-fold. Experiments, however, revealed that this excellent level of enhancement is not likely to be reached in practice. Each approach was found to be severely limited by practical problems. In addition, some of the built-in assumptions associated with these approaches were found to be insufficient or inadequate. The first approach, changing the nonchemically bonded interactions from weak to strong, Is an example of one containing inadequate assumptions. The extensive literature on intermolecular interactions, based on solution studies, shows that certain functional group pairs interact much more strongly than others. It has always been assumed that these data can be reliably extended to systems where only one member of the pair is in solution and the other Is contained in a solid surface. Our experiments this summer demonstrated that solution data do not adequately predict the strength of functional group interaction at the solid-liquid interface. Furthermore, the strong solvents needed to dissolve the monomers or polymers to which the functional groups of interest are attached compete successfully with the solid surface for the functional group. As a result, functional groups in solution cannot pair with the complementary groups in the solid surface, and the expected enhancement of nonchemically bonded interactions is not realized. The second approach, increasing the true interfacial area, is an example of one containing inadequate assumptions and suffering from numerous practical problems. First, practitioners have assumed that material removal, such as bead blasting or etching, increases true surface area (and therefore interfacial area) in a meaningful way. Our geometric analysis demonstrated that removal methods increase area by a factor of two at most. To increase interfacial area by an order of magnitude or more. a thin layer of high porosity must be added to the substrate surface prior to application of the adhesive phase. Consistent with this finding, we attempted to create a thin layer of rigid, highly porous glass on the surface of our smooth glass substrate by means of sol-gel technology. We were unable to surmount a wide variety of practical problems and obtained only collapsed, nonporous layers. Thus this approach, appealing in principle, would require long term development and is not promising in the near term. The third approach, inducing chemical bonding at the interface, is an example of one having neither inadequate assumptions nor insurmountable practical problems. When silicate glass is the substrate, there are only a few chemical reactions that can be successfully conducted to create these chemical bonds, and these reactions usually involve silicon-containing reagents. We compared the silazane reagents to the silane reagents and found through experiment that the silazanes react with the glass surface much more readily, and under milder conditions, than the silanes. The functional groups attached to the glass surface by silazane reactions were not able to be removed by solvent extraction, elevated temperature exposure, or mechanical action. This clearly indicates that the formation of chemical bonds at the interface is the most effective approach for enhancing molecular adhesion.

Penn, L. S.↗
NASA NTRS1997

Reflective Coating on Fibrous Insulation for Reduced Heat Transfer

Radiative heat transfer through fibrous insulation used in thermal protection systems (TPS) is significant at high temperatures (1200 C). Decreasing the radiative heat transfer through the fibrous insulation can thus have a major impact on the insulating ability of the TPS. Reflective coatings applied directly to the individual fibers in fibrous insulation should decrease the radiative heat transfer leading to an insulation with decreased effective thermal conductivity. Coatings with high infrared reflectance have been developed using sol-gel techniques. Using this technique, uniform coatings can be applied to fibrous insulation without an appreciable increase in insulation weight or density. Scanning electron microscopy, Fourier Transform infrared spectroscopy, and ellipsometry have been performed to evaluate coating performance.

Hass, Derek D.↗
NASA NTRS1998

Induction Bonding of Prepreg Tape and Titanium Foil

Hybrid structural laminates made of titanium foil and carbon fiber reinforced polymer composite offer a potential for improved performance in aircraft structural applications. To obtain information needed for the automated fabrication of hybrid laminates, a series of bench scale tests were conducted of the magnetic induction bonding of titanium foil and thermoplastic prepreg tape. Foil and prepreg specimens were placed in the gap of a toroid magnet mounted in a bench press. Several magnet power supplies were used to study power at levels from 0.5 to 1.75 kW and frequencies from 50 to 120 kHz. Sol-gel surface-treated titanium foil, 0.0125 cm thick, and PIXA/IM7 prepreg tape were used in several lay-up configurations. Data were obtained on wedge peel bond strength, heating rate, and temperature ramp over a range of magnet power levels and frequencies at different "power-on" times for several magnet gap dimensions. These data will be utilized in assessing the potential for automated processing. Peel strengths of foil-tape bonds depended on the maximum temperature reached during heating and on the applied pressure. Maximum peel strengths were achieved at 1.25kW and 8OkHz. Induction heating of the foil appears to be capable of good bonding up to 10 plies of tape. Heat transfer calculations indicate that a 20-40 C temperature difference exists across the tape thickness during heat-up.

Messier, Bernadette C.↗
NASA NTRS1998

High Performance Materials Applications to Moon/Mars Missions and Bases

Two classes of material processing scenarios will feature prominently in future interplanetary exploration: in situ production using locally available materials in lunar or planetary landings and high performance structural materials which carve out a set of properties for uniquely hostile space environments. To be competitive, high performance materials must typically offer orders of magnitude improvements in thermal conductivity or insulation, deliver high strength-to-weight ratios, or provide superior durability (low corrosion and/or ablative character, e.g., in heat shields). The space-related environmental parameters of high radiation flux, low weight, and superior reliability limits many typical aerospace materials to a short list comprising high performance alloys, nanocomposites and thin-layer metal laminates (Al-Cu, Al-Ag) with typical dimensions less than the Frank-Reed-type dislocation source. Extremely light weight carbon-carbon composites and carbon aerogels will be presented as novel examples which define broadened material parameters, particularly owing to their extreme thermal insulation (R-32-64) and low densities (<0.01 g/cu cm) approaching that of air itself. Even with these low-weight payload additions, rocket thrust limits and transport costs will always place a premium on assembling as much structural and life support resources upon interplanetary, lunar, or asteroid arrival. As an example, for in situ lunar glass manufacture, solar furnaces reaching 1700 C for pure silica glass manufacture in situ are compared with sol-gel technology and acid-leached ultrapure (<0.1% FeO) silica aerogel precursors.

Noever, David A.↗
NASA NTRS1999

Nanoporous Silica Thermal Insulation for Space Shuttle Cryogenic Tanks: A Case Study

Nanoporous silica (with typical 10-50 nm porous radii) has been benchmarked for thermal insulators capable of maintaining a 150 K/cm temperature gradient. For cryogenic use in aerospace applications, the combined features for low-density, high thermal insulation factors, and low temperature compatibility are demonstrated in a prototype sandwich structure between two propulsion tanks. Theoretical modelling based on a nanoscale fractal structure suggest that the thermal conductivity scales proportionally (exponent, 1.7) with the material density-lower density increases the thermal insulation rating. Computer simulations, however, support the optimization tradeoff between material strength (Young moduli, proportional to density with exponent, 3.7), the characteristic (colloidal silica, less than 5 nm) particle size, and the thermal rating. The results of these simulations indicate that as nanosized particles are incorporated into the silica backbone, the resulting physical properties will be tailored by the smallest characteristic length and their fractal interconnections (dimension and fractal size). The application specifies a prototype panel which takes advantage of the processing flexibility inherent in sol-gel chemistry.

Noever, David A.↗
NASA NTRS1998

High Performance Materials Applications to Moon/Mars Missions and Bases

Two classes of material processing scenarios will feature prominently in future interplanetary exploration- in situ production using locally available materials in lunar or planetary landings and high performance structural materials which carve out a set of properties for uniquely hostile space environments. To be competitive, high performance materials must typically offer orders of magnitude improvements in thermal conductivity or insulation, deliver high strength-to-weight ratios, or provide superior durability (low corrosion and/or ablative character, e.g. in heat shields). The space-related environmental parameters of high radiation flux, low weight and superior reliability limits many typical aerospace materials to a short list comprising high performance alloys, nanocomposites and thin-layer metal laminates (Al-Cu, Al-Ag) with typical dimensions less than the Frank-Reed-type dislocation source. Extremely light weight carbon-carbon composites and car on aerogels will be presented as novel examples which define broadened material parameters, particularly owing to their extreme thermal insulation (R-32-64) and low densities (less than 0.01 g/cc) approaching that of air itself. Even with these low weight payload additions, rocket thrust limits and transport costs will always place a premium on assembling as much structural and life support resources upon interplanetary, lunar or asteroid arrival. As an example for in situ lunar glass manufacture, solar furnaces reaching 1700 C for pure silica glass manufacture in situ are compared with sol-gel technology and acid-leached ultrapure (less than 0.1% FeO) silica aerogel precursors.

Noever, David A.↗
NASA NTRS1999

Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

Singh, Mrityunjay↗
NASA NTRS1999

Technology Demonstrator for Direct Polishing of a 50cm C/SiC Ultra Light Mirror

The NRSU portion of the contract was completed on schedule and within acceptable limits of the estimated cost. The lapping of the substrate started on schedule, and completed ahead of schedule. The polishing of the substrate was begun ahead of schedule, and was completed approximately one month ahead of schedule. It is our opinion that the substrate meets the requirements of "diffraction limited performance at 2 microns" over the measured 16 in. area. The final photos suggest that there may be edge roll-off beyond the 16 in. diameter. However, we cannot quantify this. It is our opinion that this material is suitable for use in lightweight optics as long as cladding of some type is used (Silicon, SiC, Sol-Gel, etc), as the bare material itself is too "porous" to obtain a high quality finish. We feel that this part was at the low limit of structural integrity required to mechanically polish to this level of figure requirement. Any lesser structural integrity would require some form of "non contact" figuring.

Scribner, Ken↗
NASA NTRS2000

Aerogel Projects Ongoing in MSFC's Engineering Directorate

When we speak of an aerogel material, we are referring more to process and structure am to a specific substance. Aerogel, considered the lightest solid material, has been made from silica for seventy years. Resorcinol-formaldehyde, organic aerogels have been developed more recently. However, aerogel can be made from almost any type of substance, even lead. Because an aerogel is mostly air (about 99 %), the solid substance used will affect the weight very little. The term "aerogel" connotes the sol-gel process used to manufacture the material. The aerogel begins as a liquid "sol," becomes a solid "alcogel," and is then dried to become an "aerogel." The final product has a unique structure, useful for exploitation. It is an "open pore" system with nano-sized particles and pores, has very high surface area, and is highly interconnected. Besides low weight, aerogels have ultimate (lowest) values in other properties: thermal conductivity, refractive index, sound speed, and dielectric constant. Aerogels were first prepared in 1931 by Steven Kistler, who used a supercritical drying step to replace the liquid in a gel with air, preserving the structure (1). Kistler's procedure involved a water-to-alcohol exchange step; in the 1970's, this step was eliminated when a French investigator introduced the use of tetramethylorthosilicate. Still, alcohol drying involved dangerously high temperatures and pressures. In the 1980's, the Microstructured Materials Group at Berkeley Laboratory found that the alcohol in the gel could be replaced with liquid carbon dioxide before supercritical drying, which greatly improved safety (2). 'Me most recent major contribution has been that of Deshpande, Smith and Brinker in New Mexico, who are working to eliminate the supercritical drying step (3). When aerogels were first being developed, they were evaporatively dried. However, the wet gel, when dried, underwent severe shrinkage and cracking; this product was termed "xerogel." When the autoclave drying step was introduced, the final product was without cracks and showed only minimal shrinkage; this product was termed "aerogel." In the 1990's, Deshpande, Smith and Brinker developed an evaporative drying procedure in which the wet gel is chemically "capped" so that the material, which undergoes shrinkage, springs back to its original size when evaporatively dried. This new type of xerogel, while uncracked and almost the same size as the wet gel, differs from the autoclave-dried product in that it is less porous (approximately 70%, as compared to 99% for aerogels).

Shular, David A.↗
DOE OSTI2025

Colloidal Behavior of Plutonium Oxide in Concentrated Electrolyte Solutions

The Hanford Site in Washington State manages legacy high-level radioactive waste streams that display major chemistry and engineering challenges, including the high salt levels and pH values that correspond to conditions under which many classical concepts describing chemical reactivity cannot be applied. One particular challenge that needs to be tackled at Hanford is that Pu concentrations, [Pu], in the soluble phases of the tank wastes are higher than expected based on the solubility of crystalline PuO2, which is widely accepted to be caused by the formation of PuO2 colloid, consisting of nano- to submicron-sized particles (PuO2 NPs). Fundamental research underpinning the behavior of PuO2 NPs under conditions not only relevant to the Hanford tank waste but at high ionic strength in general is needed to reliably predict the chemical reactivity of PuO2 NPs and develop engineering solutions to safely and efficiently process high-level radioactive waste into forms suitable for long-term storage. In this work, we study the behavior of PuO2 NPs (particle size ~100 nm) under high ionic strength conditions by reacting it with highly concentrated (up to 5 M) salt solutions. We explore different electrolyte compositions to elucidate the impact of different anions (NO3-, Cl-, ClO4-, SO42-, C2O42-, CO32-) on the stability of PuO2 NP in the acidic and alkaline pH regime. PuO2 NP aggregation and precipitation as function electrolyte concentration is tracked by a combination of liquid scintillation counting, dynamic light scattering for determination of particle size distributions, and zeta potentials as a proxy for particle charge. At acidic pH, electrolytes containing non-coordinating anions, such as NaNO3, NaCl, and NaClO4 mostly stabilize PuO2 NPs over a large electrolyte concentration range, showing only subtle differences in their reactivity. Other electrolyte anions show a more pronounced effect on the PuO2 NP stability: SO42-, binds directly to the particles’ surface, reverses the particle charge, and precipitates the PuO2 NPs efficiently even at intermediate sulfate concentrations (>0.1 M). In contrast, C2O42- is found to lead to high [Pu] in solution, in the milli-molar range, even at mildly acidic pH (~4). Thermodynamic modeling of the dissolved Pu concentrations using PHREEQC is unable to predict the observed [Pu] in the acidic pH regime, supporting the influence of colloids in maintaining elevated [Pu]. It is noteworthy that the current thermodynamic databases do not include constants for colloidal Pu phases and cannot accurately predict many of the high ionic strength solutions relevant to this work. The mechanisms and models responsible for these observations will need further investigation in the future. At high pH values (~12), PuO2 NPs exhibits classical sol-gel chemistry, meaning that upon destabilization of the colloidal sol, for example by addition of concentrated NaOH, highly porous and viscid PuO2 coagulates are formed that consist of a three-dimensional network likely held together by physical interactions. The PuO2 NP coagulate shows no significant reversibility of the aggregation when contacted with concentrated brines; however, PuO2 NPs can be efficiently resuspended in solution by addition of diluted electrolytes, alkaline solutions containing high amounts of carbonate, or simple addition of water. Especially carbonate is shown to stabilize PuO2 NPs in solution at high pH, characterized by stable colloidal suspensions that are resistant against sedimentation during centrifugation. Thermodynamic modeling of the carbonate system was able to predict an increasing dissolved Pu concentration with increasing carbonate concentration. However, the model was profoundly sensitive to the fixed redox potential and does not include any thermodynamic constants for colloidal Pu species.

Neumann, Julia↗
DOE OSTI2026

Visualizing Crystallization Dynamics and Transformation Pathways of Disordered Rocksalt Oxides During Thermally Activated Sol–Gel Synthesis

Sol–gel synthesis is a wet-chemical processing route for fabricating functional materials with control over composition and microstructure at relatively low temperatures compared to conventional solid-state synthesis. While sol–gel process initiates with intermixed molecular precursors, the early-stage nucleation pathways are insufficiently understood. Here, in this study, the chemical and structural transformation of ion disordered rocksalt (DRX) Li 1.2 Mn 0.4 Ti 0.4 O 2 (LMTO), a promising cathode material for lithium batteries, is studied by multiscale characterizations. In situ heating transmission electron microscopy (TEM) using a liquid cell visualizes and identifies crystallization pathways at the nanoscale. While some regions follow a classical multi-step transition through thermodynamically stable intermediates, others exhibit a kinetic shortcut via a localized amorphous matrix to directly form the DRX structure. Macroscale Fourier transform infrared spectroscopy corroborates the findings and reveals that transition metal ions are more strongly incorporated into the acetate-coordinated network than lithium. Although in situ heating TEM captures diverse local transformation pathways, in situ synchrotron X-ray diffraction indicates that the macroscopic transformation proceeds predominantly through spinel LMTO and lithium titanates toward DRX-LMTO. The findings uncover the spatiotemporal chemical and structural transformations in sol–gel derived DRX-LMTO materials, and call for fine-tuning of such sol–gel chemistries to manipulate the crystallization pathways and achieve target material homogeneity more efficiently.

cathode material↗
DOE OSTI2026

Enhanced Electrocatalytic and Cathode‐Electrolyte Interfacial Properties With a Pr‐Based Simple Perovskite/Ruddlesden‐Popper Nanocomposite Cathode in Protonic Ceramic Fuel Cells

The sluggish kinetics and poor stability of the oxygen reduction reaction (ORR) remain the primary bottleneck for achieving high performance in protonic ceramic fuel cells (PCFCs) at intermediate temperatures (400–650°C). In this work, a Pr-based nanocomposite cathode comprised of simple perovskite phase (PrNi 0.7 Co 0.3 O 3-δ ) and Ruddlesden-Popper phase (Co-doped Pr 4 Ni 3 O 10+δ ) is developed. Although PrNi 0.7 Co 0.3 O 3-δ solely stands as a good cathode with facile proton transfer, combining the superior catalytic activity against oxygen on the Ruddlesden-Popper phase boosts the ORR performance further. The designed nanocomposite cathode outperforms the simple perovskite cathode, attributed to enhanced oxygen absorption and surface diffusion with the Ruddlesden-Popper phase. A precursor-based cathode deposition technique is also developed to achieve cathode grain sizes of ∼100 nm. A single cell with the nanocomposite cathode delivers a peak power density of 1.38 W cm −2 at 650°C, among the highest in reported PCFCs with Pr-based cathodes, with a small degradation rate of 0.145 mV h −1 during 250 h stability test. Further investigation of cathode-electrolyte interface revealed interfacial PrO 2 phase formation, promoted by abundant Pr 6 O 11 in the nanocomposite precursor powder, thereby improving both ohmic resistance and stability. These findings highlight the effectiveness of the nanocomposite cathode and underscore its advantages on interfacial properties.

08 - HYDROGEN↗
DOE OSTI2025

Amorphous zinc–molybdenum–sulfide chalcogel as a long-cycle, high-capacity electrode for lithium-ion batteries

The inherent limitations of intercalation-based electrodes in lithium-ion batteries have prompted the search for alternative materials with higher specific capacities and robust electrochemical stability. Sulfur-based electrodes, despite their high theoretical capacities (1672 mAh g −1 ), typically suffer from poor cycling performance. In this work, zinc molybdenum polysulfide (Zn x Mo 3 S 13 , 0.5 ≤ x), an amorphous semiconductor chalcogel, exhibits high specific capacity and excellent cycling stability. Synchrotron X-ray pair distribution function and extended X-ray absorption fine structure analyses reveal a short-range atomic structure comprising Mo–Mo, M–S (M = Mo, Zn), and S–S bonding motifs. The coordination environment of Mo and S closely resembles that of Mo 3 S 13 clusters, interconnected via S–S bridges and Zn 2+ cations. The Li/Zn x Mo 3 S 13 cell delivers an initial discharge capacity of 844 mAh g −1 at C/3, and retains 386.2 mAh g −1 after 1000 cycles with an average coulombic efficiency of 99.99%. The distribution of relaxation times analysis confirms the formation of a stable solid electrolyte interphase, which underpins the cell's long-term stability. In conclusion, this outstanding performance is attributed to the synergistic effects of the chalcogel's unique amorphous framework, semiconductive character, Zn-mediated polysulfide anchoring, and structural resilience, positioning Zn x Mo 3 S 13 chalcogel among the most durable pure metal sulfide cathodes reported for next-generation LIBs.

36 MATERIALS SCIENCE↗