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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Cu-doping effect on dielectric properties of organic gel synthesized Ba{sub 4}YMn{sub 3−x}Cu{sub x}O{sub 11.5±δ}

Copper doped-Ba{sub 4}YMn{sub 3−x}Cu{sub x}O{sub 11.5±δ} samples were synthesized by an organic gel assisted citrate process. X-ray diffraction of compositions with x=0.002, 0.005, 0.01, 0.02 and 0.04 does not reveal any change of hexagonal perovskite structure on doping. The effects of Cu-doping on the microstructure and dielectric properties were investigated. Cu doping modifies the electrical properties at the level of the impedance characteristics of both grain and grain boundary and to understand these different behaviours, we have carried out high-resolution transmission electron microscopy analysis. Among the Ba{sub 4}YMn{sub 3−x}Cu{sub x}O{sub 11.5±δ} specimens studied, the composition x=0.002 shows a permittivity (ε′{sub r}) higher than the undoped compound and a lower loss tangent (tanδ) over several orders of magnitude of frequency. - Graphical abstract: Highlighting of many stacking faults (intergrowths) in substituted compounds with x>0.01 (right picture), which could explain the different dielectric properties observed in these compounds. However compounds with x>0.01 remain with a better stacking sequence as we can see on the left picture. Display Omitted - Highlights: • High permittivity of the Ba{sub 4}YMn{sub 3−x}Cu{sub x}O{sub 11.5±δ}. • Substitution leads to a mixed oxidation state for manganese: Mn{sup 4+}/Mn{sup 3+}. • Creation of oxygen vacancies which are responsible for stacking faults. • Highlighting relationship between Cu substitution and dielectric properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Thermoelectric properties of Fe and Al double substituted MnSi{sub γ} (γ~1.73)

Two series of Fe and Al double substituted MnSi{sub γ} chimney ladders with a nominal valence electron count, VEC=14 per transition metal were prepared (γ=1.75). Simultaneous replacement of Mn with Fe and Si with Al yielded the Mn{sub 1−x}Fe{sub x}Si{sub 1.75−x}Al{sub x} series while the second Mn{sub 1−x}Fe{sub x}Si{sub 1.75–1.75x}Al{sub 2x} series follows the pseudo-binary between MnSi{sub 1.75} and FeAl{sub 2}. Scanning electron microscopy and elemental mapping revealed that ~60% of the nominal Al content ends up in the product with the remainder lost to sublimation, and that up to 7% Al can be substituted in the main group sublattice. Profile analysis of X-ray powder diffraction data revealed gradual changes in the cell metrics, consistent with the simultaneous substitution of Fe and Al in a fixed ratio. All samples are p-type with VEC≈13.95 from the structural data and ~1×10{sup 21} holes cm{sup −3} from variable temperature Seebeck measurements. The substituted samples have lower electrical resistivities (ρ{sub 300} {sub K}=2–5 mΩ cm) due to an improved microstructure. This leads to increased thermoelectric power factors (largest S{sup 2}/ρ=1.95 mW m{sup −1} K{sup −2}) compared to MnSi{sub γ}. The thermal conductivity for the Mn{sub 0.95}Fe{sub 0.05}Si{sub 1.66}Al{sub 0.1} sample is 2.7 W m{sup −1} K{sup −1} between 300 and 800 K, and is comparable to literature data for the parent material. - Graphical abstract: The crystal structure, microstructure and thermoelectric properties of Fe and Al double substituted MnSi{sub γ} (γ~1.73) have been investigated. - Highlights: • Up to 7% Al can be substituted in MnSi{sub γ} when co-doped with Fe. • Improved microstructure and reduced electrical resistivities for Al substituted samples. • Largest power factor 1.95 mW m{sup −1} K{sup −2} and best estimated ZT=0.5.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

High elongation achieved by band-like distribution of reinforcements in aluminum matrix composites

Highlights: • The high elongation of composites with high reinforcement content has been achieved by band-like distribution of ABO. • The band-like distribution of ABO could lead to more homogenous strain distribution by scattering the damages. • The cracks played a key role in the strain non-localization process, but have negligible contribution to the tensile strain. • A model of the relationship between the ductility enhancement and the band-like distribution of ABO was established. • The residual stresses induced by band-like distribution of ABO were theoretically calculated and experimentally measured. - Abstract: Ductile aluminum matrix composites reinforced by Al{sub 18}B{sub 4}O{sub 33} whisker (ABO) with band-like distribution (Band-like Aluminum Matrix Composites, BAMCs) were fabricated by powder metallurgy and extrusion followed by annealing. The cracks tend to nucleate in the ABO-rich bands, but the band-like structure induces compressive residual stress then suppresses the crack propagation and improves the strain transferring ability in the BAMCs. The denser and smaller cracks formed in the BAMCs with higher ABO volume fraction during tensile test. These cracks play an important role in the strain non-localization process, but have negligible contribution to the tensile strain.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Bifunctional Fe{sub 3}O{sub 4}@Gd{sub 2}O{sub 3}:Eu{sup 3+}nanocomposites obtained by the homogeneous precipitation method

Graphical abstract: The TEM images reveal clearly the core–shell structures because of the obvious difference in contrast between the central part and the fringe, which indicates the Gd{sub 2}O{sub 3}:Eu{sup 3+} layer had successfully deposited on the magnetite Fe{sub 3}O{sub 4} cores. And Fe{sub 3}O{sub 4}@Gd{sub 2}O{sub 3}:Eu{sup 3+} nanoparticles keep the spherical morphology, non-aggregation and rough surface. The images reveal that the average diameters of the Fe{sub 3}O{sub 4} and Fe{sub 3}O{sub 4}@Gd{sub 2}O{sub 3}:Eu{sup 3+} nanoparticles are ∼200 nm and ∼250 nm, respectively. The thickness of Gd{sub 2}O{sub 3}:Eu{sup 3+} layer is ∼25 nm. Highlights: ► Fe{sub 3}O{sub 4}@Gd{sub 2}O{sub 3}:Eu{sup 3+} nanocomposites were synthesized by homogeneous precipitation method. ► Formation of core–shell nanostructure revealed by transmission electron microscopy. ► Fe{sub 3}O{sub 4}@Gd{sub 2}O{sub 3}:Eu{sup 3+} nanocomposites showed magnetic behavior and fluorescence properties. ► Possible applications including bioseparation, drug delivery system, bio-labels, etc. - Abstract: An easy homogeneous precipitation method was developed for the synthesis of bifunctional magnetic-fluorescent nanocomposites with Fe{sub 3}O{sub 4} nanoparticles as the core and europium-doped gadolinium oxide (Gd{sub 2}O{sub 3}:Eu{sup 3+}) as the shell. The nanocomposites showed both strong magnetic behavior and unique Eu-related fluorescence properties with a high emission intensity, which may lead to development of nanocomposites with great potential for applications in drug targeting, biosensors, and diagnostic analysis.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Screen printing large-area organometal halide perovskite thin films for efficient photodetectors

Highlights: • A stable paste with perovskite precursor was produced out. • Screen printing was proposed to fabricate perovskite thin films. • The perovskite photodetectors with symmetric architectures show reasonable performance with high photocurrent and fast response. - Abstract: Organometal halide perovskites have demonstrated excellent features compared to conventional optoelectronic materials. To date, the perovskite films have generally been fabricated by either spin coating or vapor deposition. However, both methods cannot simultaneously meet large scale and low cost of production. Here, a simple, low-cost and high-throughput strategy was proposed to fabricate perovskite thin films, which were further applied in photodetectors. First, lead compound nanoparticles were synthesized by a solvent precipitation method, then a paste with the lead compound nanoparticles was screen printed to form PbO films involving calcination, and next the PbO films directly reacted with CH{sub 3}NH{sub 3}I solution to convert into CH{sub 3}NH{sub 3}PbI{sub 3} films. The CH{sub 3}NH{sub 3}PbI{sub 3} films consisted of micron crystals, whose sizes can be effectively controlled by adjusting CH{sub 3}NH{sub 3}I concentration. Furthermore, the CH{sub 3}NH{sub 3}PbI{sub 3} films were applied in photodetectors, which showed good performance with high sensitivity and fast response.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Co-gasification of municipal solid waste and material recovery in a large-scale gasification and melting system

Highlights: Black-Right-Pointing-Pointer This study evaluates the effects of co-gasification of MSW with MSW bottom ash. Black-Right-Pointing-Pointer No significant difference between MSW treatment with and without MSW bottom ash. Black-Right-Pointing-Pointer PCDD/DFs yields are significantly low because of the high carbon conversion ratio. Black-Right-Pointing-Pointer Slag quality is significantly stable and slag contains few hazardous heavy metals. Black-Right-Pointing-Pointer The final landfill amount is reduced and materials are recovered by DMS process. - Abstract: This study evaluates the effects of co-gasification of municipal solid waste with and without the municipal solid waste bottom ash using two large-scale commercial operation plants. From the viewpoint of operation data, there is no significant difference between municipal solid waste treatment with and without the bottom ash. The carbon conversion ratios are as high as 91.7% and 95.3%, respectively and this leads to significantly low PCDD/DFs yields via complete syngas combustion. The gross power generation efficiencies are 18.9% with the bottom ash and 23.0% without municipal solid waste bottom ash, respectively. The effects of the equivalence ratio are also evaluated. With the equivalence ratio increasing, carbon monoxide concentration is decreased, and carbon dioxide and the syngas temperature (top gas temperature) are increased. The carbon conversion ratio is also increased. These tendencies are seen in both modes. Co-gasification using the gasification and melting system (Direct Melting System) has a possibility to recover materials effectively. More than 90% of chlorine is distributed in fly ash. Low-boiling-point heavy metals, such as lead and zinc, are distributed in fly ash at rates of 95.2% and 92.0%, respectively. Most of high-boiling-point heavy metals, such as iron and copper, are distributed in metal. It is also clarified that slag is stable and contains few harmful heavy metals such as lead. Compared with the conventional waste management framework, 85% of the final landfill amount reduction is achieved by co-gasification of municipal solid waste with bottom ash and incombustible residues. These results indicate that the combined production of slag with co-gasification of municipal solid waste with the bottom ash constitutes an ideal approach to environmental conservation and resource recycling.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

A substitutional quantum defect in WS2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation

Abstract Point defects in two-dimensional materials are of key interest for quantum information science. However, the parameter space of possible defects is immense, making the identification of high-performance quantum defects very challenging. Here, we perform high-throughput (HT) first-principles computational screening to search for promising quantum defects within WS 2 , which present localized levels in the band gap that can lead to bright optical transitions in the visible or telecom regime. Our computed database spans more than 700 charged defects formed through substitution on the tungsten or sulfur site. We found that sulfur substitutions enable the most promising quantum defects. We computationally identify the neutral cobalt substitution to sulfur ( $${\rm{Co}}_{{{{{{{{\rm{S}}}}}}}}}^{0}$$ Co S 0 ) and fabricate it with scanning tunneling microscopy (STM). The $${\rm{Co}}_{{{{{{{{\rm{S}}}}}}}}}^{0}$$ Co S 0 electronic structure measured by STM agrees with first principles and showcases an attractive quantum defect. Our work shows how HT computational screening and nanoscale synthesis routes can be combined to design promising quantum defects.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Midisuperspace foam and the cosmological constant

Abstract Wheeler’s conjectured ‘spacetime foam’—large quantum fluctuations of spacetime at the Planck scale—could have important implications for quantum gravity, perhaps even explaining why the cosmological constant seems so small. Here I explore this problem in a midisuperspace model consisting of metrics with local spherical symmetry. Classically, an infinite class of ‘foamy’ initial data can be constructed, in which cancellations between expanding and contracting regions lead to a small average expansion even if Λ is large. Quantum mechanically, the model admits corresponding stationary states, for which the probability current is also nearly zero. These states appear to describe a self-reproducing spacetime foam with very small average expansion, effectively hiding the cosmological constant.

Astronomy & Astrophysics↗
DOE OSTI2023

Schottky effect on the wavelength threshold for the photo-detachment from charged metallic nanoparticles

Abstract Laser-stimulated electron photo-detachment (LSPD) from nanoscale dust particles is predicted to strongly depend on the particle size. A theory of the electron photo-detachment from charged spherical metallic nanoparticles is presented. This theory is relevant to laser-stimulated photo-detachment applied to measurements of charge of nanoparticles in plasmas. Our theory predicts that the charging of nanoparticles in plasma leads to the appearance of an additional electric field, causing a change in the potential barrier at the particle boundary and consequently, a change in the effective work function, due to the Schottky effect. In this case, the critical wavelength of the laser depends not only on the work function, but also on the charge of the nanoparticles and their size.

42 ENGINEERING↗
DOE OSTI2012

Modeling the Performance of an Algebraic Multigrid Cycle Using Hybrid MPI/OpenMP

The rise of multicore cluster architectures has led to intense interest in using a combination of MPI and OpenMP to more effectively program these machines. We present a performance model for hybrid implementation of the solve cycle of algebraic multigrid (AMG), a popular iterative solver for large sparse linear systems and a key component of many scientific simulations. We validate the model on two leading parallel platforms, and discuss implications for applications programmed in a hybrid model on future machines.

Gahvari, Hormozd↗
DOE OSTI2015

The survivability of phyllosilicates and carbonates impacting Stardust Al foils: Facilitating the search for cometary water

Abstract Comet 81P/Wild 2 samples returned by NASA's Stardust mission provide an unequalled opportunity to study the contents of, and hence conditions and processes operating on, comets. They can potentially validate contentious interpretations of cometary infrared spectra and in situ mass spectrometry data: specifically the identification of phyllosilicates and carbonates. However, Wild 2 dust was collected via impact into capture media at ~6 km s −1 , leading to uncertainty as to whether these minerals were captured intact, and, if subjected to alteration, whether they remain recognizable. We simulated Stardust Al foil capture conditions using a two‐stage light‐gas gun, and directly compared transmission electron microscope analyses of pre‐ and postimpact samples to investigate survivability of lizardite and cronstedtite (phyllosilicates) and calcite (carbonate). We find the phyllosilicates do not survive impact as intact crystalline materials but as moderately to highly vesiculated amorphous residues lining resultant impact craters, whose bulk cation to Si ratios remain close to that of the impacting grain. Closer inspection reveals variation in these elements on a submicron scale, where impact‐induced melting accompanied by reducing conditions (due to the production of oxygen scavenging molten Al from the target foils) has resulted in the production of native silicon and Fe‐ and Fe‐Si‐rich phases. In contrast, large areas of crystalline calcite are preserved within the calcite residue, with smaller regions of vesiculated, Al‐bearing calcic glass. Unambiguous identification of calcite impactors on Stardust Al foil is therefore possible, while phyllosilicate impactors may be inferred from vesiculated residues with appropriate bulk cation to Si ratios. Finally, we demonstrate that the characteristic textures and elemental distributions identifying phyllosilicates and carbonates by transmission electron microscopy can also be observed by state‐of‐the‐art scanning electron microscopy providing rapid, nondestructive initial mineral identifications in Stardust residues.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Learning Forecasts of Rare Stratospheric Transitions from Short Simulations

Abstract Rare events arising in nonlinear atmospheric dynamics remain hard to predict and attribute. We address the problem of forecasting rare events in a prototypical example, sudden stratospheric warmings (SSWs). Approximately once every other winter, the boreal stratospheric polar vortex rapidly breaks down, shifting midlatitude surface weather patterns for months. We focus on two key quantities of interest: the probability of an SSW occurring, and the expected lead time if it does occur, as functions of initial condition. These optimal forecasts concretely measure the event’s progress. Direct numerical simulation can estimate them in principle but is prohibitively expensive in practice: each rare event requires a long integration to observe, and the cost of each integration grows with model complexity. We describe an alternative approach using integrations that are short compared to the time scale of the warming event. We compute the probability and lead time efficiently by solving equations involving the transition operator, which encodes all information about the dynamics. We relate these optimal forecasts to a small number of interpretable physical variables, suggesting optimal measurements for forecasting. We illustrate the methodology on a prototype SSW model developed by Holton and Mass and modified by stochastic forcing. While highly idealized, this model captures the essential nonlinear dynamics of SSWs and exhibits the key forecasting challenge: the dramatic separation in time scales between a single event and the return time between successive events. Our methodology is designed to fully exploit high-dimensional data from models and observations, and has the potential to identify detailed predictors of many complex rare events in meteorology.

Finkel, Justin↗
DOE OSTI2017

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C 5 H 8 O 4 ) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C 5 ) hydroxyl functionalization product (C 5 H 8 O 5 ) and a C 4 fragmentation product (C 4 H 6 O 3 ). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.

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

Tropical Cyclone Wind Shear-Relative Asymmetry in Reanalyses

Abstract While tropical cyclones (TCs) are axisymmetric vortices to the first order, they often exhibit noteworthy structural asymmetries. These often result from environmental vertical wind shear, which tilts the vortex and induces a wavenumber 1 pattern in the circulation and precipitation fields. Reanalyses and climate models have improved in representing the TC structure and climatology, but their relatively coarse resolution and dependence on parameterized physics cast doubt on their ability to capture the asymmetric TC structure. We perform the most comprehensive process-oriented assessment of TC asymmetry to date in reanalyses. Specifically, we analyze the composite shear-relative TC structure in ERA5 and Climate Forecast System Reanalysis (CFSR), which vary in their resolutions, physical parameterization suites, and data assimilation techniques. These structures are compared with aircraft reconnaissance radar observations. In agreement with the observations, the strongest tangential winds are usually found left-of-shear, while inner core rainfall, ascent, vortex tilt, and low-level inflow are favored directly downshear or in the downshear-left quadrant. Outer rainband convection generally peaks in the downshear-right quadrant. Thermodynamic asymmetries are also apparent, with anomalous low-level moisture right-of-shear, midlevel warmth in the upshear-right quadrant (uptilt), and cloud properties suggestive of a realistic precipitation life cycle from growth to fallout. We also decompose rainfall contributions from the convective parameterization and large-scale cloud schemes and highlight the roles of vorticity advection, buoyancy advection, and diabatic processes in driving asymmetric vertical motions in the inner core and outer rainband regions. Our results suggest that process-level studies of TC asymmetry and TC–wind shear interaction under future warming are viable using climate models. Significance Statement Asymmetries are common in tropical cyclones (TCs), influencing their intensity, track, and hazards. Vertical wind shear often plays a leading-order role in causing these asymmetries. It is uncertain how well asymmetric structures and processes are captured in reanalyses and global climate models (GCMs) with grid spacings of 0.25° and coarser. In this study, we first evaluate TC asymmetry in reanalyses, which have the benefit of being forced by observations. This helps to assess whether the resolutions associated with GCMs sufficiently capture asymmetric structures and processes and motivates upcoming work with free-running GCMs to study how TC asymmetry may change in a warming climate.

Carstens, Jacob D.↗
DOE OSTI2016

Novel Applications of the Multi-Beam SEM [Abstract Only]

The Zeiss Multi-Beam Scanning Electron Microscope (MultiSEM) was used to image a wide array samples using non-standard operating conditions. The ability of this new, high-throughput imaging technique to produce high-quality images was assessed during this one year LDRD. In addition to exploring new imaging conditions, sample preparation techniques, coupled with theoretical simulations, were explored to optimize the MultiSEM images. To obtain details about the devices imaged, as well as the experimental details, please refer to the classified report from the project manager, Bradley Gabel, or the Cyber IA lead, Justin Ford.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Grain‐Boundary‐Rich Noble Metal Nanoparticle Assemblies: Synthesis, Characterization, and Reactivity

Abstract Here, a comprehensive study on the synthesis, characterization, and reactivity of grain‐boundary (GB)‐rich noble metal nanoparticle (NP) assemblies is presented. A facile and scalable synthesis of Pt, Pd, Au, Ag, and Rh NP assemblies is developed, in which NPs are predominantly connected via Σ3 (111) twin GBs, forming a network. Driven by water electrolysis, the random collisions and oriented attachment of colloidal NPs in solution lead to the formation of Σ3 (111) twin boundaries and some highly mismatched GBs. This synthetic method also provides convenient control over the GB density without altering the crystallite size or GB type by varying the NP collision frequency. The structural characterization reveals the presence of localized tensile strain at the GB sites. The ultrahigh activity of GB‐rich Pt NP assembly toward catalytic hydrogen oxidation in air is demonstrated, enabling room‐temperature catalytic hydrogen sensing for the first time. Finally, density functional theory calculations reveal that the strained Σ3(111) twin boundary facilitates oxygen dissociation, drastically enhancing the hydrogen oxidation rate via the dissociative pathway. This reported large‐scale synthesis of the Σ3 (111) twin GB‐rich structures enables the development of a broad range of high‐performance GB‐rich catalysts.

Geng, Xin↗
DOE OSTI2018

Thermally Rearranged Polymer Membranes Containing Tröger's Base Units Have Exceptional Performance for Air Separations

Abstract The influence of segmental chain motion on the gas separation performance of thermally rearranged (TR) polymer membranes is established for TR polybenzoxazoles featuring Tröger's base (TB) monomer subunits as exceptionally rigid sites of contortion along the polymer backbone. These polymers are accessed from solution‐processable ortho‐acetate functionalized polyimides, which are readily synthesized as high‐molecular‐weight polymers for membrane casting. We find that thermal rearrangement leads to a small increase in d‐spacing between polymer chains and a dramatic pore‐network reconfiguration that increases both membrane permeability and O 2 /N 2 selectivity, putting its performance above the 2015 upper bound.

Meckler, Stephen M.↗
DOE OSTI2024

Image-based modeling of coupled electro-chemo-mechanical behavior of Li-ion battery cathode using an interface-modified reproducing kernel particle method

Abstract An interface-modified reproducing kernel particle method (IM-RKPM) is introduced in this work to allow for a direct model construction from image pixels of heterogeneous polycrystalline Li-ion battery microstructures. The interface-modified reproducing kernel (IM-RK) approximation is constructed through scaling of a kernel function by a regularized distance function in conjunction with strategic placement of interface node locations. This leads to RK shape functions with either weak or strong discontinuities across material interfaces, suitable for modeling various interface mechanics. With the placement of a triple junction node and distance-based scaling of kernel functions, the resulting IM-RK shape function also possesses proper discontinuities at the triple junctions. This IM-RK approximation effectively remedies the well-known Gibb’s oscillation in the smooth approximation of discontinuities. Different from the conventional meshfree approaches for interface discontinuities, this IM-RK approach is done without additional degrees of freedom associated with the enrichment functions, and it is formulated with the standard procedures in the RK shape function construction. This work focuses on identifying the accuracy and convergence properties of IM-RKPM for modeling the coupled electro-chemo-mechanical system. A linear patch test is formulated and numerically tested for the electro-chemo-mechanical coupled problem with a Butler–Volmer boundary condition representing the physical conditions in Li-ion battery microstructures. This is followed by verification of the optimal rates of convergence of IM-RKPM for solving the coupled problem with higher order solutions. The image-based modeling of Li-ion battery microstructures in the numerical examples demonstrates the applicability of the proposed method to realistic Li-ion battery materials modeling.

25 ENERGY STORAGE↗

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