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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Achieving extraordinary thermal stability of salt hydrate eutectic composites by amending crystallization behaviour with thickener

Commercial thermal energy storage (TES) systems necessitate reliable thermal performance throughout their operational lifetime. Repeated volume changes of the phase change materials (PCMs) during thermal cycling disengages thermal contacts between the conductive fillers like expanded graphite (EG) in TES composites, causing unstable thermal conductivity (k) that fades with cycling. Our in-operando crystallization studies on eutectic PCM made of zinc nitrate hexahydrate (ZNH) and KNO 3 revealed that the thermal stability of PCM composites can be considerably degraded by the formation of large and sharp-cornered PCM crystals during the freezing cycle. While the crystals can push EG particles, disengaging thermal contacts between them, we have newly discovered that carboxymethyl cellulose (CMC) can be used to retain the thermal contacts by forming networks of smaller PCM crystals. Furthermore, the scalable synthesis methodology of EG/ZNH eutectic composites was introduced. Here, in this study, EG particles were strongly connected into a matrix via a stable, corrosion resistant polydimethylsiloxane (PDMS) binder, stabilizing thermal networks and thereby maintaining k up to 1000 melt/freeze cycles. The thermal conductivity of our 25 vol% EG sample (13.3 W m -1 K -1 ) is more than 48% higher than other salt hydrate eutectic composites reported in the literature. We expect this study to provide insights on cooperative interaction between different components of TES systems (PCM, filler, thickener, binder) for exceptionally robust thermal properties.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Enhanced thermal reliability and performance of calcium chloride hexahydrate phase change material using cellulose nanofibril and graphene nanoplatelet

In recent years, thermal energy storage (TES) has gained attention for its role in enhancing renewable energy solutions and sustainable energy consumption. The usage of strontium chloride hexahydrate (SCH), graphene nanoplatelet (GNP), and cellulose nanofibril (CNF) additives were investigated to enhance the performance of calcium chloride hexahydrate (CCH) based on the melting/solidification behavior for TES applications. In this work, we develop a promising phase-change-material (PCM) formulation by introducing these additives that reduce supercooling, improve the thermal conductivity and stabilizing the energy storage capacity of CCH. Rheological characterizations demonstrated that the addition of 1 wt% of CNF into CCH produced the required improvement in viscosity and boosted solid-like rheological behavior. Structural characterizations show a physical mixing of the materials within the PCM composites. Our observations show that the amphiphilicity of CNF enables the surface attachment to GNP via hydrophobic interactions providing effective dispersion of GNP throughout the PCM composite. The addition of a nucleating agent, SCH decreased the degree of supercooling of ~20 g of CCH from >20 °C to 3 °C at a cooling rate of 5 °C/min. Thermal characterization showed the resulting PCM composite has a latent heat of melting of 186 Jg -1 , phase change temperature of 32 °C, and stable thermal properties after being subjected to 70 melt-freeze cycles. Adding CNF and GNP to pure CCH increased its thermal conductivity by 76 %. The high thermal conductivity of GNP and its effective dispersion by CNF is responsible for this enhancement. The study highlights the use of biodegradable nanocellulose for the preparation of sustainable PCM composites with improved performance. In conclusion, these PCM composites are scalable, they have potential to increase energy efficiency and revolutionalize the heating/cooling applications in buildings and other TES systems.

25 ENERGY STORAGE↗
DOE OSTI2025

Burn severity and vegetation type control phosphorus concentration, molecular composition, and mobilization

Shifting phosphorus (P) dynamics after wildfires can have cascading impacts from terrestrial to aquatic environments. However, it is unclear whether shifts in P composition or P concentration are responsible for changes in P dynamics post-fire. We used laboratory leaching experiments of Douglas fir forest and sagebrush shrubland chars to examine how the potential mobility of P compounds is influenced by different burn severities. Burning produced a 6.9- and 29-fold increase in particulate P mobilization but a 3.8- and 30.5-fold decrease in aqueous P released for Douglas fir forest and sagebrush shrubland, respectively. The mechanisms driving particulate- and dissolved-phase P compound mobilization were contrasting. Phosphorus compound mobilization in the particulate phase was controlled by solid char total P concentrations, while the aqueous phase was driven by solubility changes of molecular species. Nuclear magnetic resonance (NMR) and X-ray absorption near-edge structure (XANES) on the solid chars indicated that organic orthophosphate monoester and diester species were thermally mineralized to inorganic P moieties with burning in both vegetation types, which decreases P solubility. This coincided with the production of calcium- and magnesium-bound inorganic P compounds. With increasing burn severity there were systematic shifts in P concentration and composition – higher-severity chars mobilized P compounds in the particulate phase, although the magnitude of change was vegetation-specific. Our results indicate a post-fire transformation to both the composition of the solid charred material and how P compounds are mobilized, which may influence its environmental cycling and fate.

31P solution-state NMR↗
DOE OSTI2022

Ultra-compact hybrid silicon:chalcogenide waveguide temperature sensor

We demonstrate a real-time, reusable, and reversible integrated optical sensor for temperature monitoring within harsh environments. The sensor architecture combines the phase change property of chalcogenide glasses (ChG) with the high-density integration advantages of high index silicon waveguides. To demonstrate sensor feasibility, ChG composition Ge 40 S 60 , which is characterized by a sharp phase transition from amorphous to crystalline phase around 415 °C, is deposited over a 50 µ m section of a single mode optical waveguide. The phase transition changes the behavior of Ge 40 S 60 from a low loss to high loss material, thus significantly affecting the hybrid waveguide loss around the phase transition temperature. A transmission power drop of over 40dB in the crystalline phase compared to the amorphous phase is experimentally measured. Moreover, we recover the amorphous phase through the application of an electrical pulse, thus showing the reversible nature of our compact temperature sensor. Through integrating multiple compositions of ChG with well-defined phases transition temperatures over a silicon waveguide array, it is possible to determine, in real-time, the temperature evolution within a harsh environment, such as within a nuclear reactor cladding.

Badamchi, Bahareh (ORCID:0000000193105300)↗
DOE OSTI2024

Frustration-mediated crossover from long-range to short-range magnetic ordering in Y 1 – x L u x BaC o 4 O 7

The R⁢BaC⁢o 4⁢ O 7 system is a prototype geometrically frustrated magnet in which kagome planes and triangular layers of Co-O tetrahedra interleave. For R=Y, an antiferromagnetic ground state is realized due to a frustration-breaking trigonal-orthorhombic phase transition. For R = Lu, however, a long-range ordered state has rarely, if ever, been reported despite a similar symmetry-breaking transition, albeit at a significantly lower temperature. To explore this dichotomy, we present a comprehensive magnetic and structural phase diagram for Y 1-x L⁢u x BaC⁢o 4 ⁢O 7 , established through complementary neutron diffraction and magnetization measurements. Our results outline the phase evolution of the nuclear structures in response to changes in composition and temperature. Further, the temperature of the trigonal (P⁢31⁢c) to orthorhombic (Pbn⁢2 1 ) transition, T s⁢1 , decreases monotonically with increasing Lu content from 310 K for x = 0.0 to 110 K for x = 1.0. In Lu-rich compositions (0.7 ≤ x ≤ 1.0), first-order structural transitions are observed with coexisting and competing orthorhombic Pbn⁢2 1 and metastable monoclinic Cc phases. For the magnetically ordered Y-rich compositions, T- and x-dependent refinements of the magnetic structure reveal an antiferromagnetic “ribbonlike” arrangement of Co spin pairs in both the triangular and the kagome layers. A gradual suppression of long-range magnetic order is observed with increasing the Lu content, accompanied by the development of short-range magnetic correlations present in all the samples.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effects of Testosterone Supplementation on Ghrelin and Appetite During and After Severe Energy Deficit in Healthy Men

Abstract Background Severe energy deficits cause interrelated reductions in testosterone and fat free mass. Testosterone supplementation may mitigate those decrements, but could also reduce circulating concentrations of the orexigenic hormone ghrelin, thereby exacerbating energy deficit by suppressing appetite. Objective To determine whether testosterone supplementation during severe energy deficit influences fasting and postprandial ghrelin concentrations and appetite. Design and methods Secondary analysis of a randomized, double-blind trial that determined the effects of testosterone supplementation on body composition changes during and following severe energy deficit in nonobese, eugonadal men. Phase 1 (PRE-ED): 14-day run-in; phase 2: 28 days, 55% energy deficit with 200 mg testosterone enanthate weekly (TEST; n = 24) or placebo (PLA; n = 26); phase 3: free-living until body mass recovered (end-of-study; EOS). Fasting and postprandial acyl ghrelin and des-acyl ghrelin concentrations and appetite were secondary outcomes measured during the final week of each phase. Results Fasting acyl ghrelin concentrations, and postprandial acyl and des-acyl ghrelin concentrations increased in PLA during energy deficit then returned to PRE-ED values by EOS, but did not change in TEST (phase-by-group, P < 0.05). Correlations between changes in free testosterone and changes in fasting acyl ghrelin concentrations during energy deficit (ρ = -0.42, P = 0.003) and body mass recovery (ρ = -0.38; P = 0.01) were not mediated by changes in body mass or body composition. Transient increases in appetite during energy deficit were not affected by testosterone treatment. Conclusions Testosterone supplementation during short-term, severe energy deficit in healthy men prevents deficit-induced increases in circulating ghrelin without blunting concomitant increases in appetite. Clinical Trials Registration www.clinicaltrials.gov NCT02734238 (registered 12 April 2016).

Karl, J. Philip↗
DOE OSTI2024

Above room temperature multiferroic and magnetoelectric properties of (1‐Φ) PZTFT‐Φ CZFMO particulate composites

Magnetoelectric (ME) composites of suitable ferroelectric and magnetic materials can display elevated magnetic and ferroelectric operational temperatures, along with substantial ME coupling, compared to conventional single-phase multiferroics. Herein, we describe the synthesis of (1-Φ) PZTFT-Φ CZFMO, Φ = 0.1, 0.2, 0.3 (PZTFT: [0.6(PbZr 0.53 Ti 0.47 O 3 )–0.4(PbFe 0.5 Ta 0.5 )O 3 ] CZFMO: Co 0.6 Zn 0.4 Fe 1.7 Mn 0.3 O 4 )] particulate (0–3) composites and report on the magnetic as well as ferroelectric phase transitions and magnetoelectric coupling. The phase formation and the induced strain in these composites are investigated via Raman spectroscopy. A large bifurcation of the zero-field cooled-field cooled magnetization curves confirms the highly anisotropic behavior of the composites. These curves also identify spin glass behavior in the CZFMO phase at ≈230 K. The magnetic phase transition of the composite (Φ = 0.2) is reported to be ≈532 (± 10) K. The temperature dependent dielectric data displays the ferroelectric phase transitions from the PZTFT phase and the broad relaxation peak from the CZFMO phase. The quadratic relationship between the magneto-capacitance and the magnetization confirms the existence of biquadratic magnetoelectric coupling in the systems. The collective results are consistent with the presence of a direct magneto-electric effect in the composites, i.e., by the application of magnetic field, the magnetic phase is strained, and this induced strain is responsible for changes of ferroelectric order parameter in the piezoelectric phase. As a result, this attribute makes the current composite structure a promising candidate for multiferroic data storage and processing technologies.

Bhoi, Krishnamayee↗
DOE OSTI2020

Unusual electrical conductivity driven by localized stoichiometry modification at vertical epitaxial interfaces

Precise control of lattice mismatch accommodation and interfacial cation diffusion is critical to modulate correlated functionalities in epitaxial heterostructures, particularly when the interface composition is positioned near a compositional phase transition boundary. Here we select La 1-x Sr x MnO 3 (LSMO) as a prototype phase transition oxide and establish vertical epitaxial interfaces with NiO for exploring the strong interplay between strain accommodation, stoichiometry modification, and localized electron transport across the interface. It is found that localized stoichiometry modification overcomes the dead layer problem plaguing LSMO and leads to strongly directional conductivity, as manifested by a more than three orders of magnitude difference between out-of-plane and in-plane conductivity. Comprehensive atomic scale structural characterization and transport measurements reveal that this emerging behavior is created by a compositional change produced by preferential cation diffusion that pushes the LSMO phase transition from insulating into metallic within an ultrathin interface region. This study explores the nature of unusual electrical conductivity at vertical epitaxial interfaces and highlights the beneficial role of controllable cation diffusion that enables emerging functionalities for a broad range of potential applications such as memristors, spintronic devices, and novel nanoelectronic devices using strongly correlated materials.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Investigation of Frozen Chemistry for Molten Salt Reactors (MSRs)

Understanding accident progression and the potential/conditions for fission product release from fuel is necessary to evaluate safety for any nuclear reactor system. Molten Salt Reactors (MSRs) under development need such analysis to support safety evaluations. Fission product chemistry specific to MSR concepts is a critical area that introduces distinct considerations relative to the current state-of-knowledge in reactor safety, primarily developed for water-moderated nuclear reactor systems. In Light Water Reactor (LWR) systems, it is necessary to capture the chemical interaction of fission products with the reactor evironment, containment and confinement systems. The overall effects at this point are relatively well understood for the purposes of performing safety evaluations. A key insight from LWR studies is that fission product chemical behavior can be reasonably captured by modeling approaches where the chemistry is "frozen". These modeling approaches assume that radionuclide reaction and speciation can be represented by chemical classes, each with characteristic transport behavior that is invariant under a broad range of thermochemical conditions. However, radionuclides can exhibit a range of behavior in the liquid salt-melt phase of the coolant used in MSRs. Radionuclides, salt, and the metal containment surfaces (i.e. pipes) can co-exist in dynamic equilibrium that could evolve with small system mass changes. A detailed investigation to the degree the equilibrium state can dynamically evolve with changes in the conditions of the molten salt mixture has not been previously conducted. It is currently not well understood where frozen chemistry assumptions are valid. Expanding the state-of-knowledge in this regard is relevant to better assessing the range of chemical effects that should be incorporated as part of MSR safety assessments. This investigation used the Oak Ridge Isotope GENeration (ORIGEN) module of the Standardized Computer-Analysis for Licensing Evaluation (SCALE) code to generate simulated radionuclide inventories for the MSR Experiment (MSRE) and then modeled reactor chemical speciation using the Molten Salt Thermodynamic Database – Thermochemical (MSTDB-TC) coupled with Thermochimica. The effect of composition variation during decay of fission product inventory in a molten salt over a period of 500 days prolonged post- at multiple temperatures was studied. Mass fractions for fluorine and berilium were varied in order to probe the effects of free fluorine control. Finally, speciation of fluoride reactors were showed by comparing MSRE readionuclide inventories with a FLiBe based molten salt breeder reactor (MSBR). The results showed that fission product mass change has little effect on phase mass changes and vapor pressures for fluoride species, but differ with varying carrier and fuel salt compositions. However, iodine species were found to have a vapor pressure not only dependent on temperature, but also the free fluorine potential, releasing iodine when the free fluorine potential is equal to the iodine inventory. This observation, however, arose under free fluorine potentials that are very unlikely to be realized in typical molten salt mixtures. Despite this observation, temperature was found to be the dominant parameter that drove phase change and fission product species vapor pressure. The results indicate that the current frozen chemistry approach is adequate for MSR analysis.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

A room temperature exchange bias effect caused by the coexisting martensitic phase structures in Ni50Mn38Sb12−xGax polycrystalline Heusler alloys

The exchange bias effect is the physical cornerstone of applications, such as spin valves, ultra-high-density data storage, and magnetic tunnel junctions. This work studied the room temperature exchange bias effect by constructing a Ni50Mn38Sb12−xGax alloy system with coexisting martensitic phase structures. The study found that the exchange bias effect shows a non-monotonic change with the variation of Ga composition at 300 K, and an obvious room temperature exchange bias effect appears in the alloys with coexisting phase structures of 4O and L10, which is due to the strong exchange coupling between ferromagnetic and antiferromagnetic. Further research on the exchange bias effect and temperature shows that the blocking temperature is 420 K, and the exchange bias can stably exist in a temperature range of ∼200 K around room temperature. This work provides a method to engineer exchange bias effects at room temperature.

Physics↗
DOE OSTI2024

Wildfire‐induced increases in photosynthesis in boreal forest ecosystems of North America

Abstract Observations of the annual cycle of atmospheric CO 2 in high northern latitudes provide evidence for an increase in terrestrial metabolism in Arctic tundra and boreal forest ecosystems. However, the mechanisms driving these changes are not yet fully understood. One proposed hypothesis is that ecological change from disturbance, such as wildfire, could increase the magnitude and change the phase of net ecosystem exchange through shifts in plant community composition. Yet, little quantitative work has evaluated this potential mechanism at a regional scale. Here we investigate how fire disturbance influences landscape‐level patterns of photosynthesis across western boreal North America. We use Alaska and Canadian large fire databases to identify the perimeters of wildfires, a Landsat‐derived land cover time series to characterize plant functional types (PFTs), and solar‐induced fluorescence (SIF) from the Orbiting Carbon Observatory‐2 (OCO‐2) as a proxy for photosynthesis. We analyze these datasets to characterize post‐fire changes in plant succession and photosynthetic activity using a space‐for‐time approach. We find that increases in herbaceous and sparse vegetation, shrub, and deciduous broadleaf forest PFTs during mid‐succession yield enhancements in SIF by 8–40% during June and July for 2‐ to 59‐year stands relative to pre‐fire controls. From the analysis of post‐fire land cover changes within individual ecoregions and modeling, we identify two mechanisms by which fires contribute to long‐term trends in SIF. First, increases in annual burning are shifting the stand age distribution, leading to increases in the abundance of shrubs and deciduous broadleaf forests that have considerably higher SIF during early‐ and mid‐summer. Second, fire appears to facilitate a long‐term shift from evergreen conifer to broadleaf deciduous forest in the Boreal Plain ecoregion. These findings suggest that increasing fire can contribute substantially to positive trends in seasonal CO 2 exchange without a close coupling to long‐term increases in carbon storage.

Biodiversity & Conservation↗
DOE OSTI2024

Atomistic simulations to reveal HIP-bonding mechanisms of Al6061/Al6061

Molecular dynamics simulations were employed to understand the diffusion bonding process during hot isostatic pressing (HIP) of Al6061/Al6061 alloy. Simulations of the HIP process reveal atomistic phenomena that are difficult or unlikely to be observed experimentally and provide useful insights into the mechanism of diffusion and bonding. Here, the results reveal that at the start of the HIP process, a massive incursion of oxygen atoms occurs from the pre-existing γ-Al 2 O 3 to the 6061 region across the interphase interface. These oxygen atoms interact with the enriched Mg atom layer present at the existing γ-Al 2 O 3 and 6061 matrix to form a secondary complex Mg 2 Al 2 O 5 phase. Diffusion calculations also show that transport of atoms due to the applied pressure is 4–5 orders of magnitude higher than would occur in the absence of HIP conditions. The Mg 2 Al 2 O 5 phase also provides efficient pathways for the rapid transport of Mg atoms. Because of the higher diffusion coefficients observed for Mg within the phase, Mg atoms can move more swiftly compared to their diffusion within other phases such as γ-Al 2 O 3 . This accelerated mobility facilitates the rapid movement of Mg atoms across the interface, leading to changes in the local composition and the potential growth of the Mg 2 Al 2 O 5 phase.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Processing of phase change materials by fused deposition modeling: Toward efficient thermal energy storage designs

We report that recently, several efforts have emerged that employ additive manufacturing techniques to integrate phase change material (PCM) thermal energy storage into geometrically complex designs for advanced thermal management. In this work, we contribute to this emerging research by reporting on the production of a composite nylon-based filament for fused deposition modeling incorporating encapsulated PCMs for 3D printing heat sink geometries. Microencapsulated PCM (MEPCM) with a 6 degrees C transition temperature was selected as the material for thermal energy storage. This transition temperature was selected due to its suitability to provide thermal energy storage to target air-conditioning applications in buildings. In an attempt to improve the thermal conductivity of the composite, fine boron nitride fillers were added, although the effect on improvement was found to be negligible in the overall composite mixture. The nylon-MEPCM ratio in the filaments was optimized, and filaments containing up to 40 wt% MEPCM were successfully synthesized, which were found optimal for 3D printing complex heat sink and other geometries. Thermal and mechanical properties of the filaments were characterized, including latent heat of fusion, thermal conductivity, phase change temperature, tensile strength, and more. Thermal infrared imaging of heat sink geometries printed using the MEPCM filaments undergoing thermal discharging was also conducted. This work presents the most promising result to date in the open literature for a 3D-printed PCM composite in the combination of size, energy density, and geometric complexity of printed parts.

25 ENERGY STORAGE↗
DOE OSTI2022

Electrical and structural properties of binary Ga–Sb phase change memory alloys

Material properties of Ga–Sb binary alloy thin films deposited under ultra-high vacuum conditions were studied for analog phase change memory (PCM) applications. Crystallization of this alloy was shown to occur in the temperature range of 180–264 °C, with activation energy >2.5 eV depending on the composition. X-ray diffraction (XRD) studies showed phase separation upon crystallization into two phases, Ga-doped A7 antimony and cubic zinc-blende GaSb. Synchrotron in situ XRD analysis revealed that crystallization into the A7 phase is accompanied by Ga out-diffusion from the grains. X-ray absorption fine structure studies of the local structure of these alloys demonstrated a bond length decrease with a stable coordination number of 4 upon amorphous-to-crystalline phase transformation. Mushroom cell structures built with Ga–Sb alloys on ø110 nm TiN heater show a phase change material resistance switching behavior with resistance ratio >100 under electrical pulse measurements. TEM and Energy Dispersive Spectroscopy (EDS) studies of the Ga–Sb cells after ∼100 switching cycles revealed that partial SET or intermediate resistance states are attained by the variation of the grain size of the material as well as the Ga content in the A7 phase. A mechanism for a reversible composition control is proposed for analog cell performance. These results indicate that Te-free Ga–Sb binary alloys are potential candidates for analog PCM applications.

Ume, Rubab (ORCID:0000000324766900)↗
DOE OSTI2022

High Entropy Oxide Relaxor Ferroelectrics

Relaxor ferroelectrics are important in technological applications due to strong electromechanical response, energy storage capacity, electrocaloric effect, and pyroelectric energy conversion properties. Current efforts to discover and design materials in this class generally rely on substitutional doping as slight changes to local compositional order can significantly affect the Curie temperature, morphotropic phase boundary, and electromechanical responses. In this work, we demonstrate that moving to the strong limit of compositional complexity in an ABO 3 perovskite allows stabilization of relaxor responses that do not rely on a single narrow phase transition region. Entropy-assisted synthesis approaches are utilized to synthesize single-crystal Ba(Ti 0.2 Sn 0.2 Zr 0.2 Hf 0.2 Nb 0.2 )O 3 [Ba(5B)O] films. The high levels of configurational disorder present in this system are found to influence dielectric relaxation, phase transitions, nanopolar domain formation, and Curie temperature. Temperature-dependent dielectric, Raman spectroscopy, and second-harmonic generation measurements reveal multiple phase transitions, a high Curie temperature of 570 K, and the relaxor ferroelectric nature of Ba(5B)O films. The first-principles theory calculations are used to predict possible combinations of cations to design relaxor ferroelectrics and quantify the relative feasibility of synthesizing these highly disordered single-phase perovskite systems. Further, the ability to stabilize single-phase perovskites with various cations on the B-sites offers possibilities for designing high-performance relaxor ferroelectric materials for piezoelectric, pyroelectric, and electrocaloric applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Optimizing the combustion synthesis of FeAlxOy catalysts for microwave-assisted thermocatalytic dehydrogenation of fossil fuels

The growing demand for hydrogen requires the development of clean and energy-efficient technologies for its synthesis. Microwave-assisted thermocatalytic dehydrogenation of fossil fuels has demonstrated the potential to produce H2 with high yield and selectivity, and simultaneously generate valuable nanostructured carbon byproducts. In prior work, iron-based alumina (FeAlxOy) catalysts for this process were made via solution combustion synthesis (SCS). However, the effect of SCS parameters on the dehydrogenation performance is not well understood. The present study investigates this by varying the SCS fuel, Fe:Al molar ratio, and heating mode. The results show subtle changes of these parameters can result in significant differences in the phase composition, specific surface area, and microwave absorbing properties of FeAlxOy, which all affect microwave-assisted dehydrogenation. Notably, H2 selectivity can be increased from 30% to 74%. Statistical testing determined that the SCS fuel used was the most significant SCS parameter affecting dehydrogenation performance.

Chanoi, Zachary A.↗
DOE OSTI2024

Pathway to High Rate Capability in Interconnected Composite Electrolytes: A Case Study with a Single-Ion-Conducting Polymer

In a three-dimensional interconnected polymer/ceramic composite electrolyte (3D composite), both the polymer and ceramic electrolyte phases are individually connected with a polymer-rich surface layer to provide conformal contact with the electrodes. This work investigates how the transference number of the polymer phase affects the electrochemical properties of the 3D composite. Here, we fabricate a 3D composite using a “single-ion” conducting polymer electrolyte (PE), Li 1+x+y Al x Ti 2–x Si y P 3–y O 12 (LICGC) ceramic, and compare its electrochemical properties with the neat polymer, and with a 3D composite made with a dual-ion-conducting PE (we reported previously). Our results reveal that changing the polymer phase from a dual-ion-conducting PE to a single-ion-conducting PE results in a 9-fold increase in the limiting current density, although the interfacial impedance between the polymer and LICGC ceramic remains high (and contributes significantly to the total impedance of the 3D composite). Further, the limiting current density of the 3D composite is dictated by the PE and minimally affected by the ceramic scaffold. The ceramic scaffold, however, helps to ease the concentration gradient buildup within the PE and moderately improves the overall transference number. The LICGC scaffold does not provide any additional Li dendrite resistance due to its high reactivity with Li.

25 ENERGY STORAGE↗