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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 OSTI2025

Evolved Gas Analysis–Mass Spectrometry Exposes Polymer Network Structures

Polymer network structures in epoxy thermosets play an important role in the final thermoset material properties. However, analytical characterization of these network structures is difficult due to their amorphous nature. In this work, the application of evolved gas analysis–mass spectrometry (EGA-MS) to characterize the polymer network structures of bisphenol A (BPA)-based thermosets is demonstrated. Analytical characterization of the polymer network structures is accomplished by monitoring the Product-Specific Kinetics (PSK) of BPA monomer formation during thermal degradation investigations. We relate observed differences in the activation energy (E a ) of BPA monomer formation to the local packing environment around the BPA monomer units within the polymer network. Variations in the local environment related to the polymer networks manifest qualitatively as broadening in the thermal profile of the BPA monomer evolution and quantitatively as changes in the activation energy (E a ). Three BPA thermoset formulations were investigated; two amine-cured thermoset with 4,4′-diaminodiphenylmethane (DDM) or poly(propylene glycol) bis(2-amino-propyl ether) (PPG400) and a homopolymerized thermoset via curing with Epikure 3253 catalyst (3253). Results revealed that the 3253 thermoset contained two distinct packing densities in the polymer network, while DDM and PPG400 thermosets had uniform distributions of packing densities. Results from the DDM thermoset revealed a gradually decreasing E a , while the apparent E a of PPG400 was consistent over the entire degradation. Furthermore, these differences in E a were concluded to stem from the flexibility of the corresponding polymer networks and the ability of the network components to rearrange and occupy formed voids. Due to the minimal sample required for analysis (100–200 μg), this EGA-MS technique has great potential for postproduction evaluation of composite parts to identify changes in the polymer networks from use and aging, which could signal compromised performance.

Degradation↗
DOE OSTI2022

Design and Performance of lithium-Ion Batteries for Achieving Electric Vehicle Takeoff, Flight, and Landing

Today, the burgeoning drive towards global urbanization with over half the earth’s population living in cities, has created major challenges with regards to intracity and intercity transit and mobility. This problem is compounded due to the fact that almost always urbanization and increase in standard of living drives individual automobile ownerships. Over 95% of automobiles are presently powered by some form of fossil fuel and as an unintended consequence, urban centers have also been centers for peak greenhouse gas emissions, a major contributor to global climate change. A revolutionary solution to this conundrum is flight capable electric automobiles or electric aerial vehicles that can tackle both urban mobility and climate change challenges. For such advanced electric platforms, energy storage and delivery component is the vital component towards achieving takeoff, flight, cruise, and landing. The requirements and duty cycle demands on the energy storage system is drastically different when compared to the performance metrics required for terrestrial electric vehicles. As the widely deployed lithium ion-based battery systems are often the primary go-to energy storage choice in electric vehicle related applications, it is imperative that performance metrics and specifications for such batteries towards areal electric vehicles need to be established. In this nascent field, there exists ample opportunities for battery material innovations, understanding degradation mechanism, battery design, development and deployment of battery control and management systems. Thus, this chapter comprehensively discusses battery requirements and identifies battery material chemistries suitable for handling aerial electric automobile duty cycles. The chapter also discusses the battery cell-level metrics pertaining to electrochemical, chemical, mechanical, and structural parameters. Furthermore, specific models for battery degradation, state of health (SOH), capacity and models for full cell performance and degradation are also discussed here. Finally, the chapter also discusses battery safety and future directions of batteries that would power these next generation urban electric aircrafts.

Amin, Ruhul↗
DOE OSTI2023

PDMS ‐silica composite gas separation membranes by direct ink writing

Abstract Polydimethylsiloxane (PDMS)‐based membranes containing amine‐functionalized and unfunctionalized silica particles were fabricated via direct ink writing for CO 2 /N 2 gas separation. The printability of the inks was evaluated by rheological measurements, while spectroscopy, microscopy, thermal measurements, and mechanical testing were employed to characterize the printed membranes. The surface morphology of the membranes revealed the absence of voids, demonstrating their suitability for gas separation. The printed membranes also exhibited desirable thermal and mechanical properties (i.e., thermal degradation temperature of 518 °C and tensile strength as high as 1.178 MPa with 529% elongation). The PDMS‐based membranes generally displayed high permeability for CO 2 but slightly low selectivity for the CO 2 /N 2 gas pair. The best‐combined permeability‐selectivity performance of 8794 barrer and selectivity of 11.64 was demonstrated by the printed PDMS membrane containing no SiO 2 fillers. The inclusion of unfunctionalized SiO 2 particles generally increased the membrane's gas permeability but compromised the selectivity. In contrast, membranes with amine‐functionalized silica showed improved selectivity compared to membranes containing unfunctionalized silica. Overall, the performance and characteristics offered by the PDMS/silica composite membranes demonstrated the potential of 3D printing as an economical and sustainable fabrication approach to developing materials for carbon capture applications.

Gutierrez, Dianne B.↗
DOE OSTI2026

Effect of Storage Conditions on Efficacy of Poly(ethylenimine)-Alumina CO 2 Sorbents

Solid amine sorbents are one of the primary components of DAC technologies that allow for the removal of ultradilute CO 2 from the atmosphere. A main drawback in the implementation of solid amine sorbents in industrial-scale DAC applications is their instability under certain operational or storage conditions over an extended period. In this work, the effect of storage temperature and gas composition in the storage headspace on the long-term stability of a poly(ethylenimine)-alumina (PEI/γ-Al 2 O 3 ) sorbent is explored. PEI/γ-Al 2 O 3 sorbents with 70 and 100% pore filling are aged under varying gases (N 2 , O 2 , Ar, 0.04% CO 2 −N 2 , CO 2 , and ambient air) in an oven (40 °C), at common ambient indoor temperature conditions (23 °C), or in a freezer (−4 °C). The CO 2 sorption capacity, as measured by thermogravimetric analysis (TGA), along with FTIR spectra of the fresh and aged sorbents, reveal that at 23 and −4 °C, storage under ambient air or inert gas (Ar) provides reasonable long-term stability, with <13% degradation over 12 and 5 months of storage. Interestingly, with storage at 40 °C, similar levels of deactivation were observed under pure O 2 and N 2 after 4 months of storage, which suggests that nonoxidative thermal reactions can occur under prolonged storage conditions under N 2 . In contrast, with storage under CO 2 , sorbent degradation is substantially suppressed compared to storage under N 2 , ambient air, O 2 , or Ar, yielding sorbents with no observable loss in capacity after 2 months, compared to a 66, 63, and 62% loss under N 2 , ambient air, and N 2 in the same period at 40 °C, respectively. Overall, these findings provide guidance for practical amine sorbent storage in academic or industrial settings where amine sorbents are used for carbon capture.

Atmospheric chemistry↗
DOE OSTI2021

Multiscale Understanding of Surface Structural Effects on High-Temperature Operational Resiliency of Layered Oxide Cathodes

The worldwide energy demand in electric vehicles and the increasing global temperature have called for development of high-energy and long-life lithium-ion batteries (LIBs) with improved high temperature operational resiliency. However, current attention has been mostly focused on cycling aging at elevated temperature, leaving considerable gaps of knowledge in the failure mechanism and practical control of abusive calendar aging and thermal runaway that are highly related to the eventual operational lifetime and safety performance of LIBs. Herein, using a combination of various in situ synchrotron X-ray and electron microscopy techniques, we report a multiscale understanding of surface structure effects involved in regulating the high temperature operational tolerance of polycrystalline Ni-rich layered cathodes. Our results collectively show that an ultraconformal poly (3,4-ethylenedioxythiophene) coating can effectively prevent LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode from undesired phase transformation and transition metal dissolution on the surface, atomic displacement and dislocations within primary particles, intergranular cracking along the grain boundaries within secondary particles, and intensive bulk oxygen release during high state-of-charge and high temperature aging. As a result, the present work highlights the essential role of surface structure controls in overcoming the multiscale degradation pathways of high-energy battery materials at extreme temperature.

25 ENERGY STORAGE↗
DOE OSTI2024

Bench-Scale Testing of Monolithic PPI Structured Contactors for Direct Air Capture of CO 2

The overall project objective was to develop, optimize and bench-scale test the integrated embodiment of a leading direct air capture (DAC) sorbent composition, linear-poly(propylenimine) (l-PPI), in a structured material system, specifically a monolithic contactor for achieving low pressure drop, to justify its further scale-up in a subsequent program. The project team was led by CORMETECH, a leading monolithic gas/solid contactor manufacturer for environmental applications, and included Global Thermostat, a well-known DAC start-up, and Georgia Tech, a prominent US academic institution in carbon capture and DAC. The monolithic contactor for l-PPI in this project employed an advanced, cost-effective fabrication technique from CORMETECH, namely a porous monolith substrate directly impregnated with the amine, an approach contrasting to the traditional wash-coating methods used for activating monoliths. The l-PPI monolithic contractor is targeted for use in DAC systems such as the Global Thermostat DAC process, which involves the cyclic operation of ambient air flow over a monolithic amine contactor followed by steam-mediated thermal desorption and CO 2 collection, maximizing volumetric productivity while reducing the auxiliary power required to capture CO 2 from air. The Global Thermostat DAC process currently utilizes poly(ethyleneimine) (PEI) materials as baseline sorbents, which are subject to oxidative degradation and slow capacity fade at the elevated temperature required for efficient CO 2 removal. Georgia Tech, with Global Thermostat, had discovered in lab-scale efforts that l-PPI had superior resistance to oxidative degradation compared to PEI, with similar CO 2 adsorption capacity. While the novel l-PPI sorbent offers significant advantages over PEI for DAC, including potential design simplification and increased process efficiency, it is not commercially available, and prior to this project, had not yet been evaluated on the bench-scale in a structured contactor.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Direct Functionalization of Established 3D-Printed Aza-Michael Liquid Crystal Elastomers with Donor–Acceptor Stenhouse Adducts

Extrusion 3D printing has advanced the manufacturing of complex liquid crystal elastomer (LCE) architectures. In parallel, donor–acceptor Stenhouse adducts (DASAs), a class of white-light-responsive photoswitches, have enabled both photochemical and photothermal LCE actuation. However, DASA–LCEs have yet to be extruded and 3D-printed. Two key challenges exist: DASA’s inherent sensitivity to heat and radicals can lead to degradation during ink preparation and printing, and small changes in the concentration of the added DASA component impact the properties of the extrudable ink, requiring reoptimization of well-established 3D-printing protocols. To overcome these challenges, we present a post-printing functionalization strategy that circumvents these limitations. Residual secondary amines, inherent to inks synthesized via standard aza-Michael addition, serve as active sites for covalent attachment of DASA photoresponsive groups following printing and cross-linking. Our method means that DASAs can be directly grafted onto 3D-printed aza-Michael LCEs without modifying the ink formulation or processing. The resulting DASA–LCEs exhibit wavelength tunability within the visible range and a variety of photothermal and photochemical responses. The post-functionalization can occur within 2 min and enables spatial control of the DASA concentration, producing films with tunable color gradients and locally varied photothermal and photochemical responses under visible light. In conclusion, this approach enables the rapid fabrication of DASA-based light-responsive LCEs using established ink formulations with the potential for the design of complex 3D architectures.

3D printing↗
DOE OSTI2022

Native lattice strain induced structural earthquake in sodium layered oxide cathodes

Abstract High-voltage operation is essential for the energy and power densities of battery cathode materials, but its stabilization remains a universal challenge. To date, the degradation origin has been mostly attributed to cycling-initiated structural deformation while the effect of native crystallographic defects induced during the sophisticated synthesis process has been significantly overlooked. Here, using in situ synchrotron X-ray probes and advanced transmission electron microscopy to probe the solid-state synthesis and charge/discharge process of sodium layered oxide cathodes, we reveal that quenching-induced native lattice strain plays an overwhelming role in the catastrophic capacity degradation of sodium layered cathodes, which runs counter to conventional perception—phase transition and cathode interfacial reactions. We observe that the spontaneous relaxation of native lattice strain is responsible for the structural earthquake (e.g., dislocation, stacking faults and fragmentation) of sodium layered cathodes during cycling, which is unexpectedly not regulated by the voltage window but is strongly coupled with charge/discharge temperature and rate. Our findings resolve the controversial understanding on the degradation origin of cathode materials and highlight the importance of eliminating intrinsic crystallographic defects to guarantee superior cycling stability at high voltages.

25 ENERGY STORAGE↗
DOE OSTI2024

Iodide manipulation using zinc additives for efficient perovskite solar minimodules

Abstract Interstitial iodides are the most critical type of defects in perovskite solar cells that limits efficiency and stability. They can be generated during solution, film, and device processing, further accelerating degradation. Herein, we find that introducing a small amount of a zinc salt- zinc trifluoromethane sulfonate (Zn(OOSCF 3 ) 2 ) in the perovskite solution can control the iodide defects in resultant perovskites ink and films. CF 3 SOO ̶ vigorously suppresses molecular iodine formation in the perovskites by reducing it to iodide. At the same time, zinc cations can precipitate excess iodide by forming a Zn-Amine complex so that the iodide interstitials in the resultant perovskite films can be suppressed. The perovskite films using these additives show improved photoluminescence quantum efficiency and reduce deep trap density, despite zinc cations reducing the perovskite grain size and iodide interstitials. The zinc additives facilitate the formation of more uniform perovskite films on large-area substrates (78-108 cm 2 ) in the blade-coating process. Fabricated minimodules show power conversion efficiencies of 19.60% and 19.21% with aperture areas of 84 and 108 cm 2 , respectively, as certified by National Renewable Energy Laboratory (NREL), the highest efficiency certified for minimodules of these sizes.

14 SOLAR ENERGY↗
DOE OSTI2022

Building interface bonding and shield for stable Li-rich Mn-based oxide cathode

Implementation of Li-rich Mn-based oxide cathode with high-energy-density has been restrained by capacity/voltage degradation that results from irreversible lattice oxygen loss and structure rearrangements. To resolve these challenges, in this work, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 encapsulated by amorphous Co x B (CB-LRM) is rationally designed via autocatalytic plating for highly reversible cationic/anionic hybrid cathode material. Band coherency is ingeniously evoked by interface-reconstruction between bulk structure and amorphous coating layer, which lower the energy of O $2p$ states. Furthermore, this is associated with strengthened orbital hybridization of O $2p$-Mn $3d$ and increased formation energy of oxygen vacancy, which mitigates the lattice oxygen loss considerably. Additionally, interface shielding effects that protect electrode against electrolyte corrosion and the reduction of surface oxygen are also present with fully coverage of amorphous Co x B coating layer. As a result, the as-designed CBLRM cathode exhibits excellent cycle stability after 100 loops with only 0.154% per cycle capacity fade and improved voltage degradation. Given this, this work provides a potential avenue for rational design of lattice oxygen-based electrode materials with high-energy-density.

25 ENERGY STORAGE↗
DOE OSTI2022

Hydrothermal synthesis of Co-free NMA cathodes for high performance Li-ion batteries

Scalable and sustainable production of high voltage cathodes is required to meet the increasing demands for Li-ion batteries. Additionally, the anticipated scarcity of critical materials like cobalt necessitates demonstration of Co-free alternatives that can match the performance metrics of conventional cathodes. Herein, a hydrothermal synthesis route for production of a new class of high-capacity, cobalt-free cathode material, LiNi 0.9 Mn 0.05 Al 0.05 O 2 (NMA9055) for next-generation Li-ion batteries is reported. In this work, the synthesized cathode material shows high crystallinity and purity with monodispersed spherical morphology. Extensive electrochemical, structural, and post-mortem characterization of this novel NMA material is carried out. NMA-Li half cells show an initial discharge capacity of 200 mAh/g with a 96% capacity retention over 100 cycles when cycled between 3.0 and 4.4 V. On the other hand, NMA full cells with Li 4 Ti 5 O 12 (LTO) electrodes as the anode, show an initial discharge capacity of 186 mAh/g with 81% capacity retention over 200 cycles. Post-mortem structural and morphological characterization show that the NMA morphology and crystal structure do not degrade significantly over 200 charge/discharge cycles. This new class of cobalt free cathode material containing nickel, manganese and aluminum synthesized by an ammonia-free synthesis route is expected to provide a facile solution towards sustainable cathode production.

25 ENERGY STORAGE↗
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

Distinct Dynamics of Lithium Intercalation and Plating on Graphite Anode for Li‐Ion Batteries in eVTOL Applications

In the absence of viable high-energy-density battery alternatives, lithium-ion (Li-ion) batteries remain essential for enabling electric vertical take-off and landing (eVTOL) platforms in advanced air mobility. Unlike Li-ion batteries used in electric vehicles and portable electronics, eVTOL battery systems operate under distinct high-power demands, which necessitate an independent assessment of material degradation mechanisms. This study presents a case analysis of graphite anode evolution under high-power cycling conditions. The findings reveal lithium entrapment within graphite particles, potentially resulting from incomplete Li-ion de-intercalation during a high-rate discharge event that is characteristic of eVTOL take-off and landing. This phenomenon leads to a progressive reduction in graphite-specific capacity and, over time, promotes lithium metal plating on the anode. Notably, the Li-metal plating observed in this study differs from that associated with fast-charging conditions, as it is primarily governed by concentration polarization-induced overpotential in the latter case. In conclusion, these findings highlight the inherent challenges of utilizing graphite in high-power Li-ion battery applications and elucidate the unique degradation mechanisms that arise due to the sluggish reaction kinetics of Li-ion intercalation and de-intercalation within graphite.

Li plating↗
DOE OSTI2022

Origin and regulation of oxygen redox instability in high-voltage battery cathodes

Oxygen redox at high-voltage has emerged as a transformative paradigm for high-energy battery cathodes such as layered transition-metal oxides by offering extra capacity beyond conventional transition-metal redox. However, these cathodes suffer from voltage hysteresis, voltage fade, and capacity drop upon cycling; single-crystalline cathodes have recently shown some improvements but these challenges still remain. We reveal the fundamental origin of oxygen redox instability to be originated from the domain boundaries that are present in single-crystalline cathode particles. By synthesizing single-crystalline cathodes free of domain boundaries, we show that the elimination of domain boundaries enhances the reversible lattice oxygen redox while inhibiting the irreversible oxygen release. Further, this leads to significantly suppressed structural degradation and improved mechanical integrity during battery cycling and abuse heating. The robust oxygen redox enabled through domain boundary control provides practical opportunities towards high-energy, long-cycling, and safe batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Hydrazine-free precursor for solution-processed all-inorganic Se and Se 1− x Te x photovoltaics

Selenium (Se) has reemerged as a promising absorber material for indoor and tandem photovoltaics (PVs), and its alloys with Te (Se 1−x Te x ) offer a widely tunable bandgap. Solution processing of this materials system offers a route to low-cost fabrication. However, solution processing of Se has, thus far, only used hydrazine, which is an extremely hazardous solvent. In this work, we prepare and isolate propylammonium poly-Se and poly-Se–Te precursors from a safer thiol-amine solvent system. We formulate molecular inks by dissolving the precursor in dimethylformamide (DMF) with a monoethanolamine (EA) additive and process high-quality Se and Se 1−x Te x films with bandgaps ranging from 1.20 eV to 1.86 eV. We fabricate PVs from these films using TiO 2 and MoO 3 charge transport layers (CTLs) to achieve power conversion efficiencies as high as 2.73% for Se and 2.33% for Se 0.7 Te 0.3 under solar simulation. Se devices show excellent stability with no degradation after 1 month in air, enabled by the excellent stability of Se and the use of inorganic CTLs. This work represents an important step towards low-cost solution-phase processing of Se and Se 1−x Te x alloys for PVs and photodetectors with low toxicity and high bandgap tunability.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Volatile Products of the Autoxidation of Poly(ethylenimine) in CO 2 Sorbents

Poly(ethyleneimine) (PEI)-based CO 2 sorbents are a promising material class for use in CO 2 capture applications, particularly direct air capture (DAC), due to their high amine content and CO 2 capacities. The sorbent lifetime is a key uncertainty in the deployment of these materials in such applications, as they oxidize under conditions relevant to candidate DAC process cycles. Here, in this study, we utilize thermogravimetric analysis/differential scanning calorimetry/FTIR spectroscopy to characterize the nature, rate, and quantity of volatile species formed from the oxidation of PEI when supported on mesoporous Al 2 O 3 . We show that NH 3 , CO 2 , and H 2 O are primary volatile species formed from PEI oxidation and that their production rate matches the overall oxidation rate as measured via heat flow from a differential scanning calorimeter. We show that the total quantity of NH 3 evolved is consistent with terminal primary amines being cleaved from the polymer chain and that approximately one hydrogen atom per PEI repeat unit reacts to form H 2 O during the reaction. Finally, metadynamics and quantum chemical simulations performed on a simplified system are used to highlight the likely importance of radicals in the elementary reactions that comprise the oxidation reaction set. The findings here represent the first characterization of the volatile products from the oxidation of PEI in CO 2 sorbents and lead to a greater understanding of the mechanisms behind the oxidative degradation of these materials.

36 MATERIALS SCIENCE↗