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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
DOE OSTI2023

A novel approach to identify the ionomer phase in PEMFC by EELS

Proton exchange membrane fuel cells are one of the most promising technologies of energy conversion for both automotive and stationary applications, due to their ultimate cleanness and high efficiency. A critical factor, which strongly affects the fuel cell performance, is the ionomer distribution and coverage over the carbon support, since the catalysts, which are typically Pt and/or Pt-alloy nanoparticles, must be located at the carbon support/ionomer interface to catalyze the sluggish oxygen reduction reaction. However, the characterization and identification of the ionomer film, in terms of ionomer distribution and coverage over the carbon surface, is a long standing challenge. This is because the ionomer film may suffer from beam damage during the characterization, either from x-rays, neutrons or an electron beam, which causes morphological changes. In this regard, we report here a novel approach to identify and differentiate the ionomer, using the carbon signal produced by STEMEELS. Using this approach, not only the ionomer distribution, but also the carbon support distribution, can be probed at high spatial resolutions. In addition, this new approach allows us to identify ionomer-rich and carbon-support rich regions, which are quite challenging to determine using other methods.

08 HYDROGEN↗
DOE OSTI2022

Compositionally complex doping for zero-strain zero-cobalt layered cathodes

We report the high volatility of the price of cobalt and the geopolitical limitations of cobalt mining have made the elimination of Co a pressing need for the automotive industry. Owing to their high energy density and low-cost advantages, high-Ni and low-Co or Co-free (zero-Co) layered cathodes have become the most promising cathodes for next-generation lithium-ion batteries. However, current high-Ni cathode materials, without exception, suffer severely from their intrinsic thermal and chemo-mechanical instabilities and insufficient cycle life. Here, in this paper, by using a new compositionally complex (high-entropy) doping strategy, we successfully fabricate a high-Ni, zero-Co layered cathode that has extremely high thermal and cycling stability. Combining X-ray diffraction, transmission electron microscopy and nanotomography, we find that the cathode exhibits nearly zero volumetric change over a wide electrochemical window, resulting in greatly reduced lattice defects and local strain-induced cracks. In-situ heating experiments reveal that the thermal stability of the new cathode is significantly improved, reaching the level of the ultra-stable NMC-532. Owing to the considerably increased thermal stability and the zero volumetric change, it exhibits greatly improved capacity retention. This work, by resolving the long-standing safety and stability concerns for high-Ni, zero-Co cathode materials, offers a commercially viable cathode for safe, long-life lithium-ion batteries and a universal strategy for suppressing strain and phase transformation in intercalation electrodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Influence of Cryomilling on Crystallite Size of Aluminum Powder and Spark Plasma Sintered Component

The present investigation aims to develop nanocrystalline (NC) pure aluminum powders using cryomilling technique and manufacture bulk components using spark plasma sintering (SPS). The cryomilling was performed on pure Al powders for 2, 6, and 8 h. The cryomilled powders were then consolidated using SPS to produce bulk components. The particle morphology and crystallite size of the powders and the bulk SPS components were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the crystallite size of pure Al powders decreases with increased cryomilling time. The results also showed that the SPS at elevated temperatures resulted in a slight increase in crystallite size, however, the changes were insignificant. The mechanical properties of the bulk components were determined using a Vickers microhardness tester. The hardness of the cryomilled SPS component was determined to be three times higher than that of the unmilled SPS component. The mechanism for the reduction in crystallite size with increasing cryomilling time is discussed. This fundamental study provides an insight into the development of bulk nanomaterials with superior mechanical properties for automotive, aerospace, marine, and nuclear applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Rapid grain refinement and compositional homogenization in a cast binary Cu50Ni alloy achieved by friction stir processing

Friction stir processing (FSP) has been increasingly adopted for joining and processing materials in automotive, aerospace and industrial construction. During FSP a dynamic competition between high-speed shear deformation and deformation-induced heating brings about a complex competition between multiple dynamic microstructural evolution mechanisms making it difficult to predict the microstructural evolution pathway. Hence, improved understanding of microstructural evolution mechanisms during FSP can be beneficial for continued growth in the adoption of FSP for demanding applications of future. Towards this goal, this study uses a model binary Cu – 50 at.% Ni alloy to clarify the effect of single and double pass FSP on the microstructural evolution of a coarse grained and compositionally heterogeneous cast microstructure. High energy synchrotron X-ray diffraction, electron backscatter diffraction, and nanoindentation are used to clarify the microstructural evolution due to FSP. The process of compositional homogenization of as-cast segregations is studied by energy dispersive spectroscopy and atom probe tomography. Our results show that a single fast FSP pass at 30 mm.s -1 produces a 100 µm deep layer of submicrometric and hall-petch hardened CuNi grains. The initial cast compositional heterogeneities in a micrometric scale is rapidly transformed to nano-sized domains, mainly confined at grain boundaries. Double pass FSP increases the penetration depth of the processed layer and leads to a 2.9 times grain growth relative to single pass FSP. Grain fragmentation, discontinuous dynamic recrystallization, grain growth, and twinning mechanisms are discussed. In conclusion, these results highlight the value of FSP for ultrafast grain refinement and compositional homogenization of cast alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Achieving superior mechanical properties: Tailoring multicomponent microstructure in AISI 9254 spring steel through a two-stage Q&P process and nanoscale carbide integration

In the pursuit of lightweight, durable steel, we have successfully developed a multicomponent structure in AISI 9254 spring steel using a two-stage quenching and partitioning (Q&P) process. The primary objective of this process was to engineer an optimized microstructure consisting of nanobainite, martensite, and nano-carbides. Utilizing the insights gained from the results of advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atom probe tomography (APT) performed on the as-received AISI 9254 spring steel, we refined the quenching and partitioning (Q&P) path, leading to the successful establishment of a bainitic transformation for superior mechanical properties. Our tensile tests revealed a high yield strength (≈ 1600 ± 25 MPa) and ultimate tensile strength (≈ 1850 ± 50 MPa), along with considerable elongation (≈ 11.15 ± 0.25%). We also identified that pre-formed martensite lath defects and high silicon content play crucial roles during the Q&P process, preventing carbide coalescence and increasing strain-hardening capacity. Finally, this study demonstrates the potential of a Q&P process to generate high-strength, ductile steel for automotive and aerospace applications.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Insights into the mechanisms of NH3 inhibition on Cu-CHA SCR catalysts

This work elucidates the atomic-scale mechanism behind ammonia (NH3) inhibition during the selective catalytic reduction (SCR) of NO? on Cu-CHA catalysts, a key issue limiting low-temperature emission control. Using SCR kinetic analysis, operando electron paramagnetic resonance (EPR) spectroscopy, and density functional theory (DFT), we demonstrate that NH3 inhibition primarily slows the oxidation half-cycle (OHC), while the reduction half-cycle (RHC) remains unaffected. DFT simulations reveal that excess NH3 substantially increases the diffusion barrier for CuI ions, hindering formation of essential CuII-oxo dimer intermediates and thus suppressing OHC kinetics. Operando EPR studies confirm that this inhibition strongly depends on operating temperature and catalyst Cu loading. Our findings highlight strategies to counteract NH3 inhibition, including optimizing Cu loading, precisely managing NH3:NO feed ratios, and enhancing CuI ion mobility through tailored catalyst design and operational adjustments, thereby advancing the efficiency of emission control technologies in automotive applications.

Deka, Dhruba Jyoti↗
DOE OSTI2023

ML-ACCEPT: Machine-Learning-enhanced Automated Circuit Configuration and Evaluation of Power Converters

This project, ML-ACCEPT, took a significant step toward achieving the first objective of the DIFFERENTIATE program: to help engineers to more rapidly and cost-effectively consider a wider range of more novel concepts before selecting an engineering-optimal architecture for high-fidelity detailed design and evaluation. Compared to existing methods, the ML-ACCEPT project investigated innovative technologies to make the design of power converters more cost-effective and time-efficient by i) integrating recent breakthroughs in ML, power electronics, simulation software, and optimization to research, develop, and developed a suite of ML-enhanced hypothesis generation tools for power converter design; and ii) facilitating the integration of the proposed software tools into existing power-converter design work-flows. Some existing tools for power-converter design have a certain level of intelligence to aid the design process, but to our knowledge none of them has ML-enhanced capability of automating the electrical circuit design process by selecting, configuring, and tailoring the individual components that enable available resources (e.g., high-voltage DC power) to be converted to the desired output (e.g., lower-voltage DC power with a desired voltage ripple), subject to application-specific (e.g., plasma generation and automotive applications) thermal and packaging considerations. The state-of-the-art circuit design of power converters is still heavily reliant on human experts to select the optimal topology and search for design parameters with human’s experience and intuitions, which can be very time-consuming, inefficient, and labor intensive. The team is composed of University of Michigan-Dearborn (UM-Dearborn), Lawrence Livermore National Laboratory (LLNL), Oak Ridge National Laboratory (ORNL), Modelon Inc., and lighthouse customers.

42 ENGINEERING↗
DOE OSTI2023

Nontraditional Approaches To Enable High-Energy and Long-Life Lithium–Sulfur Batteries

In this study, lithium-sulfur (Li-S) batteries are promising for automotive applications due to their high theoretical energy density (2600 Wh/kg). In addition, the natural abundance of sulfur could mitigate the global raw material supply chain challenge of commercial lithium-ion batteries that use critical elements, such as nickel and cobalt. However, due to persistent polysulfide shuttling and uncontrolled lithium dendrite growth, Li-S batteries using nonencapsulated sulfur cathodes and conventional ether-based electrolytes suffer from rapid cell degradation upon cycling. Despite significant improvements in recent decades, there is still a big gap between lab research and commercialization of the technology. To date, the reported cell energy densities and cycling life of practical Li-S pouch cells remain largely unsatisfactory. Traditional approaches to improving Li-S performance are primarily focused on confining polysulfides using electronically conductive hosts. However, these micro- and mesoporous hosts suffer from limited pore volume to accommodate high sulfur loading and the associated volume change during cycling. Moreover, they fail to balance adsorption-conversion of polysulfides during charge-discharge, leading to the formation of massive dead sulfur. Such hosts are themselves electrochemically inactive, which decreases the practical energy density. In contrast, a series of nontraditional approaches, paired with advances in multiscale mechanistic understanding, have recently demonstrated exciting performance outcomes not only in conventional coin cells but also in practical pouch cells. In this Account, we first introduce our novel cathode design strategies to overcome polysulfide shuttling and sluggish redox kinetics in thick S cathodes via selenium-sulfur chemistry and cathode host engineering. Next, we gain a mechanistic understanding of Li-S batteries in various types of electrolytes via a series of spectroscopic, nuclear magnetic resonance, and electrochemical methods. Meanwhile, a novel cathode solid electrolyte interphase encapsulation strategy via nonviscous highly fluorinated ether-based electrolyte is introduced. The established selection rule by investigating how solvating power retards the shuttle effect and induces robust cathode/solid-electrolyte interphase formation is also included. We then discuss how the synergistic interactions between rational cathode structures and electrolytes can be exploited to tailor the reaction pathways and kinetics of S cathodes under high mass loading and lean electrolyte conditions. In addition, a novel interlayer design to simultaneously overcome degradation processes (polysulfide shuttling and lithium dendrite formation) and accelerate redox reaction kinetics is presented. Finally, this Account concludes with an overview of the challenges and strategies to develop Li-S pouch cells with high practical energy density, long cycle life, and fast-charging capability.

25 ENERGY STORAGE↗
DOE OSTI2025

Evaluating the bond strength and fracture mechanisms of cold-sprayed zinc coating on AZ91 magnesium substrate via a combined experimental and computational approach

Magnesium (Mg) alloys are ideal candidates for automotive applications due to their high strength to weight ratio, castability, recyclability etc., however, they lack corrosion and oxidation resistance. Solid-state deposition techniques, such as cold spray, have been demonstrated to enhance their corrosion resistance as it relies on the severe plastic deformation of powder particles upon impact with the substrate to form a metallurgical bond with the substrate and within the coating. At cold sprayed interfaces, a heterogeneous microstructure is formed that includes some porosity, oxides and intermetallics which can significantly affect coating performance. Thus, establishing a direct correlation between the interface microstructure and its properties can aid in designing optimal cold spray parameters. In this study, we investigated the microstructure and mechanical properties of a zinc (Zn) coating deposited on a high pressure die cast (HPDC) AZ91 Mg substrate via high resolution scanning transmission electron microscopy, in situ micro-tensile testing, and finite element method (FEM) modeling. Micro-tensile pillars fabricated using the plasma focused ion beam (PFIB) successfully isolates the coating-substrate interface within the gauge length. The average bond strength of Zn-Mg interface was determined to be ∼140 MPa with failure occurring partially at the interface and mostly into the coatings. A detailed microstructural characterization revealed evidence of a strong metallurgical bonding at the Zn-Mg interface and formation of the C14 MgZn 2 laves phase interlayer resulting in a mixed mode of fracture during the micro-tensile experiments. FEM modeling reveals the stress distribution along the interfaces and suggests that a MgZn 2 layer thickness between 200–400 nm is optimum to increase the bond strength and minimize the triaxiality. Such a site-specific interfacial analysis with correlative computational modeling provides crucial insight into the overall performance of cold spray interfaces.

Bond strength↗
DOE OSTI2025

High-Speed and Hysteresis-Free Near-Infrared Optical Hydrogen Sensor Based on Ti/Pd Bilayer Thin Films

Palladium (Pd) and titanium (Ti) exhibit opposite dielectric responses upon hydrogenation, with stronger effects observed in the near-infrared (NIR) region. Leveraging this contrast, we investigated Ti/Pd bilayer thin films as a platform for NIR hydrogen sensing—particularly at telecommunication-relevant wavelengths, where such devices have remained largely unexplored. Ti/Pd bilayers coated with Teflon AF (TAF) and fabricated via sequential electron-beam and thermal evaporation were characterized using optical transmission measurements under repeated hydrogenation cycles. The Ti (5 nm)/Pd (x = 2.5 nm)/TAF (30 nm) architecture showed a 2.7-fold enhancement in the hydrogen-induced optical contrast at 1550 nm compared to Pd/TAF reference films, attributed to the hydrogen ion exchange between the Ti and Pd layers. The optimized structure, with a Pd thickness of x = 1.9 nm, exhibited hysteresis-free sensing behavior, a rapid response time (t90 < 0.35 s at 4% H2), and a detection limit below 10 ppm. It also demonstrated excellent selectivity with negligible cross-sensitivity to CO2, CH4, and CO, as well as high durability, showing less than 6% signal degradation over 135 hydrogenation cycles. These findings establish a scalable, room-temperature NIR hydrogen sensing platform with strong potential for deployment in automotive, environmental, and industrial applications.

Chemistry↗
DOE OSTI2025

Compression Response of Silicone-Based Composites with Integrated Multifunctional Fillers

Polydimethylsiloxane (PDMS) is known for its exceptional mechanical properties, chemical stability, and flexibility. Recent advancements have focused on developing functional PDMS composites by integrating various functional fillers, including polymers, ceramics, and metals, for advanced applications such as electronics, medical devices, and aerospace. Consequently, there is a growing need to investigate PDMS composites to achieve higher filler loadings offering enhanced mechanical performance. This study addresses this need by utilizing the high molecular weight (MW) PDMS resin we have developed, offering its high elongation capacity of up to >6500%. We incorporated boron (B), hollow glass microballoons (HGMs), and tungsten-coated hollow glass microballoons (WHGMs) into the developed high MW PDMS. The resulting composites demonstrated excellent elastic properties and significant compression resilience (35–80%) and elastic modulus (1.28–10.15 MPa) at high filler loadings (~60 vol.%). Specifically, B/PDMS composites achieved up to 67.6 vol.% of B, HGM/PDMS composites held up to 68.6 vol.% of HGM, and WHGM/PDMS composites incorporated up to 54.0 vol.% of WHGM. These findings highlight the potential of high MW PDMS for developing high-performance PDMS composites suitable for advanced applications such as aerospace, automotive, and medical devices.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Single-Phase Jet Impingement Cooling for a Power-Dense Silicon Carbide Power Module

The adoption of silicon carbide (SiC) devices in the electric vehicle (EV) industry is increasing due to their superior performance over silicon devices. SiC devices enable further miniaturization of EV inverters, increasing their power density, which results in thermal management challenges. Here in this paper, the limits of single-phase jet impingement cooling are explored for an automotive SiC power module. We propose embedding pin fins in the direct-bonded-copper (DBC) substrate of the power module package using laser powder bed fusion additive manufacturing. The thermalhydraulic performance of the DBC-embedded pin fins is compared against folded fins that are directly soldered to the DBC substrate. A heat conduction analysis was conducted on a SiC package to determine the target heat transfer coefficient (HTC) for the heat sink. A water-ethylene glycol (WEG) jet impingement on the proposed concepts was studied using unit-cell models to achieve the target HTC. The studied designs put emphasis on the reliability and manufacturability requirements of the automotive industry. The thermal performance of DBC-embedded pin fins outperformed the DBC-soldered folded fins. The performance of the DBC-embedded pin fins is benchmarked against WEG-based cooling systems of commercial EVs. With the proposed cooling solution, we have shown a pathway of reducing the specific thermal resistance by 75% compared to BMW i3 thermal management system without any penalty on pressure drop or parasitic power.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2024

Formation and Detriments of Residual Alkaline Compounds on High-Nickel Layered Oxide Cathodes

High-nickel layered oxides LiNi x M 1-x O 2 (x ≥ 0.9) have emerged as promising cathode materials for automotive batteries due to their high energy density and lower cost. However, the formation and accumulation of surface alkaline compounds during storage hinder their mass production and commercialization. Here, in this study, a validated chemical method is employed to deconvolute and quantify the evolution of each residual lithium compound in four representative cathodes during ambient-air storage, viz., LiNiO 2 (LNO), LiNi 0.95 Co 0.05 O 2 (NC), LiNi 0.95 Mn 0.05 O 2 (NM), and LiNi 0.95 Al 0.05 O 2 (NA). Furthermore, the activation energy of the reaction between water and the cathode is determined by measuring the leached LiOH concentration at various temperatures. While residual lithium and time-of-flight secondary-ion mass spectrometry measurements collectively reveal that the air stability overall follows the trend of NM > NA ≈ NC > LNO, the aged NM exhibits the highest charge-transfer resistance and the worst electrochemical performance among the cathodes. In situ, X-ray diffraction and scanning transmission electron microscopy unveil that the aged NM is plagued by a large area of resistive spinel-like M 3–x Li x O 4 phases, leading to aggravated particle reaction heterogeneity. Finally, a one-step recalcination method is demonstrated effective in fully restoring the degraded cathodes. This work provides insights into overcoming air sensitivity issues of high-Ni cathodes.

(S)TEM↗
DOE OSTI2023

Ballistic characterization of additively manufactured extrusion deposited thermoplastic composite plates

Additive manufacturing (AM) is rapidly emerging in high performance applications such as army ground vehicles, automotive and transportation. However, the response of AM parts/components to extreme loading such as high velocity impacts is less studied. In this work, the performance under ballistic impact of AM panels is evaluated using a medium velocity gas gun, generating projectile velocities up to 400 m/s. The preferential print orientation properties are considered in order to evaluate whether the panels exhibit isotropic or anisotropic behavior under impact. Surface morphology is investigated by milling the beads smooth on samples and comparing the impact on as-printed samples to those that are smoothed. The effect of nickel chromium micron (nichrome) wire embedded in the AM panels (during print) of polycarbonate-carbon fiber (PC-CF) and polycarbonate-glass fiber (PC-GF) are explored. Thermoplastic polyurethane-acrylonitrile butadiene styrene/carbon fiber (TPU-ABS/CF), Acrylonitrile butadiene styrene-carbon-fiber (ABS-CF) AM samples absorbed >50% of the impact energy. The ballistic performance was noted to be in the following order – ABS-CF > TPU-ABS/CF > PC. Scanning electron microscopy (SEM) was conducted to study the interface between the nichrome wire and the polymer-fiber matrix. This work is the first of its kind exploring into the capabilities of AM panels as ballistic materials. This study leads the way for developing AM panels that are easily manufactured and exhibit superior ballistic resistance.

Landrie, Dakota M.↗
DOE OSTI2020

Mechanisms of paint bake response in resistance spot-welded first and third generation AHSS

Implementation of 3rd generation advanced high strength steels (3GAHSS) in automotive structures requires careful consideration of joining process implications. Due to the presence of increased carbon equivalent in 3GAHSS such as 980 HF relative to commonly-applied 1st generation AHSS such as 980 DP, the resultant properties of the weld nugget and heat affected zones in resistance spot welded must be engineered to provide consistent and acceptable performance, specifically in cross-tension loading mode. Although the as-welded cross-tension strength (CTS) of 980 HF is less than 980 DP, there is a significant improvement of the CTS after paint baking in 980 HF welds. 980 DP steel welds do not exhibit such marked improvement upon baking. The mechanism of the strong and beneficial effect of paint baking on 980 HF in comparison to 980 DP is discussed in light of its effect on residual stress distributions and microstructures. Although residual stress (strain) reduction is observed via synchrotron x-ray diffraction for all tested steels, this effect is demonstrated as secondary to the performance restoration of the weld joint in cross tension. High-resolution electron channeling contrast imaging (ECCI) micrographs reveal that paint baking affects a more beneficial degree of martensite tempering in 980 HF as compared to 980 DP. The martensite tempering is also evidenced by both a reduction in nano-hardness of critical microstructural features and re-emergence of ductile fracture behavior following the paint baking process. The tempering of martensite is concluded to be the dominant mechanism in improving cross tension strength of 3GAHSS welds following paint baking.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Mitigate Stress Corrosion Cracking (SCC) in High-strength Al Castings (CRADA 508)

Development of high strength, corrosion resistant, aluminum alloys is important to a number of industries, including automotive, aerospace, power, etc. Understanding how processing methods such as casting, chemistry, additives and recycle content affect an alloy’s microstructure and performance in real world environments is crucial to their implementation. One major concern is how the repeated exposure to saline solutions can be detrimental to the structural integrity of aluminum alloy components. This study was undertaken as a collaboration between Eck Industries and PNNL to investigate the stress corrosion cracking (SCC) and corrosion behavior of aluminum alloys. This work examines the SCC response of three different materials set. First is cast A206 Al alloy produced by three different casting techniques (i.e., permanent mold, and sand casting with and without chill) and with or without nano forming additives as potential grain refiners. The second materials set comprises Al alloy tubes extruded by PNNL’s ShAPE process and produced using raw material with three different ratios of twitch and pre-consumer Al 6061 scrap. Finally, the third materials set comprises two Al-Si-Mg-Fe alloys with controlled Si% and Fe% to mimic recycle grade Al alloys. The corrosion behavior of these materials was characterized using SCC testing and scanning electrochemical cell microscopy (SECCM) technique; mechanical behavior was characterized using tensile testing, and microstructure was characterized using optical and electron microscopy techniques. Of the A206 Al alloys, the samples with nano forming additives performed poorly compared to those without. The best SCC performance (i.e. least degradation in mechanical properties) was demonstrated by A206 alloy sand cast with chill while the permanent mold sample showed the worst SCC performance. The SECCM was performed on A206 alloy sand cast with chill to understand the effect of microstructure and determine the location-dependent corrosion properties on grain boundaries (GB) and inside grains (IG) on the sample. The corrosion potential and current measured on GB and IG at various points on the sample established that the GB locations are more cathodic and corrosive than the IG locations. Further work needs to be conducted to investigate the mechanisms behind the observed dependence of SCC on casting technique and nano forming additives. Among the ShAPE extruded tubes, SECCM data suggests the decreasing order of tendency to corrode as follows: 100% twitch > 75% twitch > 50% twitch. Finally, both variants of the Al-Si-Mg-Fe alloys showed a large volume fraction of Fe- and Si-containing intermetallics and additional work is needed to discern differences in their respective corrosion responses. In summary, correlating local electrochemical behavior (e.g. via SECCM) with micro/nanostructure, in conjunction with bulk mechanical behavior, can help identify the right fabrication method and alloy chemistry to minimize SCC issues in Al alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Batteries Annual Progress Report (FY2019)

The Vehicle Technologies Office (VTO) of the Department of Energy (DOE) conducts research and development (R&D) on advanced transportation technologies that would reduce the nation’s use of imported oil and would also lead to reductions in harmful emissions. Technologies supported by VTO include electric drive components such as advanced energy storage devices (primarily batteries), power electronics and electric drive motors, advanced structural materials, energy efficient mobility systems, advanced combustion engines, and fuels. VTO is focused on funding early-stage high-reward/high-risk research to improve critical components needed for more fuel efficient (and cleaner-operating) vehicles. One of the major VTO objectives is to enable U.S. innovators to rapidly develop the next generation of technologies that achieve the cost, range, and charging infrastructure necessary for the widespread adoption of plug-in electric vehicles (PEVs). An important prerequisite for the electrification of the nation’s light duty transportation sector is development of more cost-effective, longer lasting, and more abuse-tolerant PEV batteries. One of the ultimate goals of this research, consistent with the current vehicle electrification trend, is an EV which can provide the full driving performance, convenience, and price of an internal combustion engine (ICE) vehicle. To achieve this, VTO has established the following overarching goal (Source: FY2021 Congressional Budget Justification1): …identify new battery chemistry and cell technologies with the potential to reduce the cost of electric vehicle battery packs by more than half, to less than $100/kWh (ultimate goal is $60/kWh battery cell cost), increase range to 300 miles, and decrease charge time to 15 minutes or less by 2028. VTO works with key U.S. automakers through the United States Council for Automotive Research (USCAR) – an umbrella organization for collaborative research consisting of Fiat Chrysler Automobiles (FCA), the Ford Motor Company, and General Motors. Collaboration with automakers through the partnership known as U.S. Driving Research and Innovation for Vehicle Efficiency and Energy Sustainability (U.S. DRIVE) attempts to enhance the relevance and the success potential of its research portfolio. VTO competitively selects projects for funding through funding opportunity announcements (FOAs). Directly-funded work at the national laboratories are awarded competitively through a lab-call process. During the past year, VTO continued R&D in support of PEVs. Stakeholders for VTO R&D include universities, national laboratories, other government agencies and industry (including automakers, battery manufacturers, material suppliers, component developers, private research firms, and small businesses). This document summarizes the progress of VTO battery R&D projects supported during the fiscal year 2019 (FY 2019).

25 ENERGY STORAGE↗
DOE OSTI2023

Independence of Environmental and Mechanical Damages on Silicone Adhesive Stored in a Thermo-Oxidative Environment

Abstract Elastomeric polymer materials hold a special place in today’s industrial sectors with respect to structural application needs. Low quality materials are detrimental to industries like aerospace, and automotive engineering. Assessment of the durability of elastomers for structural applications has been of much interest among the literary circles for decades and new materials keep outperforming the existing ones. Polymeric adhesives are one of the most abundantly used materials in these industries. All polymeric materials get damaged when in contact with aggressive environments in presence of high temperature and oxygen. Commonly referred to as thermo-oxidation, this environment exposes the material to heat and oxidation reactions in presence of oxygen. Resultantly, during service life, the damage to the polymer matrix is primarily caused by two factors: mechanical damage and environmental aging. Environmental aging is an irreversible phenomenon caused by changes in the molecular structure while mechanical damage maintains the shape of the polymer matrix, and the deterioration is mostly due to polymer chain mobility. Environmental aging can be caused by a single environmental agent or by a synergized impact of several environmental elements. Increasing temperature is found to be proportional to decreasing tensile strength and toughness of material. The rate and extent of degradation can be accessed by scrutinizing the changes in constitutive behavior of material through mechanical and chemical properties. Accelerated thermal aging is among the most common modes of process related degradation, leading generally to chain scission, and crosslinking phenomena and reduced resistance to fracture stress, and strain. In this experimental study, our goal is to separate the environmental degradation from mechanical damage. A silicone-based adhesive was aged in thermo-oxidative at (0%RH) aging environment. The damage and decay mechanisms have been used to draw a distinction between environmental degradation and mechanical damage. Material characterization included uniaxial tensile test (failure and cyclic) and scanning electron microscopy (SEM) tests on as-received and aged samples. Aging was conducted at three different temperatures (60°C, 80°C and 95°C) and six different exposure durations (1, 3, 10, 30, 90 and 200 days). This work confirms that environmental damage is superposed on top of the mechanical damage, and thus, they are separable. The total mechanical and environmental damage is a synergized effect of all exposure conditions and parameters involved i.e., aging time, temperature, and oxygen. The chemistry and mechanics of the polymer degradation were found to be in good agreement with each other.

Alazhary, Sharif↗