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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Spectral Rear Irradiance Testing and Modeling for Degradation and Performance of Solar Fields: Preprint

This work investigates how the spectrum of irradiance incident on the rear of solar modules impacts their degradation, and in case of bifacial PV their performance. We calculate the spectral irradiance incident on the rear of modules through raytrace simulations and validate with measured field data collected from a 75kW single axis-tracked bifacial test site. An equation to calculate relative degradation is shown, showing that current acceleration factors for UV damage in chambers can be off by +3% for the rear surfaces. Finally, a method for improving non-spectral simulations is proposed.

bifacial performance↗
DOE OSTI2023

Physics-informed Data-driven Degradation and Prognostic For Hydropower System

The hydropower system is a cyber-physical system, and the industry is experiencing high operation and maintenance (O&M) costs along with increasing unplanned outages, primarily due to aging equipment and new asset loading patterns. Current (O&M) practices in asset management are predominantly reactive rather than predictive and systematic. To address these challenges, a proposed physics-informed data-driven degradation model aims to simulate the health of components in various environments. Its purpose is to accurately characterize wear and fatigue in the pilot components of hydropower systems. Additionally, the model provides informed confidence in prognostic predictions concerning asset degradation and remaining life.

13 HYDRO ENERGY↗
DOE OSTI2025

Environmental degradation testing of Alloy 709

Alloy 709 is an advanced austenitic stainless steel developed to meet the demanding conditions of sodium fast reactors (SFRs) but may also be of use for lead fast reactors, high temperature gas reactors, and molten salt reactors. Understanding environmental degradation modes and quantifying degradation rates are crucial to ensure the long-term, reliable operation of these reactors. This paper discusses recent neutron irradiation results, future neutron irradiation test plans, and sodium corrosion testing to communicate current best understanding of the performance of Alloy 709 in SFR environments.

A709↗
DOE OSTI2025

Development of Surveillance Test Articles for Materials Degradation Management in MSR Environments

Materials in molten salt reactors (MSR) undergo accelerated degradation from corrosion, irradiation, and cyclic loads at elevated temperatures. Establishing a materials surveillance program to enable the assessment of material deterioration is critical to assure structural integrity of MSRs components. This presentation summarizes recent efforts towards the development of surveillance test articles for collecting various damages for monitoring materials degradation. Surveillance test articles with reduced dimensions were designed to capture creep-fatigue damage from cyclic loading at elevated temperatures. The strain evolution of test articles during thermal cycling was analyzed both numerically and experimentally. Out-of-reactor thermal cycling demonstrated successful capture of strain range for materials assessment. Moreover, test articles were subject to both mechanical loads and molten salt exposure, and the damage due to stress and corrosion was investigated. Additionally, damage inference models were developed to predict the remaining life of materials based on the accumulated damage in surveillance test articles.

36 - MATERIALS SCIENCE↗
DOE OSTI2022

Tailoring Disordered/Ordered Phases to Revisit the Degradation Mechanism of High‐Voltage LiNi 0.5 Mn 1.5 O 4 Spinel Cathode Materials

Abstract In the spinel oxide cathode family, LiNi 0.5 Mn 1.5 O 4 (LNMO) shows a high operating voltage (≈4.7 V vs Li/Li + ) and excellent Li‐ion mobility with stable 3D conducting channels. Ni/Mn cation disordered and ordered phases usually coexist in LNMO materials, and they have distinct structural and electrochemical properties, resulting in different battery performances for LNMO materials with different phase compositions. Identifying the correlation between phase compositions and electrochemical properties is of significance to the improvement of battery performance and understanding of degradation mechanisms. Herein, the disordered/ordered phase compositions in LNMO materials are tailored by post‐annealing strategies and their impacts on electrochemical performance and degradation mechanisms from the surface to the bulk are systematically investigated. The ordered phase increases rapidly as Mn 3+ is oxidized to Mn 4+ through a post‐annealing process. LNMO with an intermediate fraction of disordered and ordered phases gives rise to improved cycling stability. This article further reports that a high ordered phase fraction can preferentially protect Ni from dissolution during cycling. However, these results suggest that the transition metal dissolution and surface structural change of LNMO do not exhibit a direct correlation with cycling stability. These results indicate the capacity fading mainly correlates with the bulk structural distortion, leading to decreased Li‐ion kinetics.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Degradation Pathways of Cobalt–Free LiNiO 2 Cathode in Lithium Batteries

Electrode-electrolyte reactivity (EER) and particle cracking (PC) are considered two main causes of capacity fade in high-nickel layered oxide cathodes in lithium-based batteries. However, whether EER or PC is more critical remains debatable. Herein, the fundamental correlation between EER and PC is systematically investigated with LiNiO 2 (LNO), the ultimate cobalt-free lithium layered oxide cathode. Specifically, EER is found more critical than secondary particle cracking (SPC) in determining the cycling stability of LNO; EER leads to primary particle cracking, but mitigates SPC due to the inhibition of H2-H3 phase transformation. Two surface degradation pathways are identified for cycled LNO under low and high EERs. A common blocking surface reconstruction layer (SRL) containing electrochemically-inactive Ni 3 O 4 spinel and NiO rock-salt phases is formed on LNO in an electrolyte with a high EER; in contrast, an electrochemically-active SRL featuring regions of electron- and lithium-ion-conductive LiNi 2 O 4 spinel phase is formed on LNO in an electrolyte with a low EER. These findings unveil the intrinsic degradation pathways of LNO cathode and are foreseen to provide new insights into the development of lithium-based batteries with a minimized EER and a maximized service life.

25 ENERGY STORAGE↗
DOE OSTI2023

A Guideline to Mitigate Interfacial Degradation Processes in Solid‐State Batteries Caused by Cross Diffusion

Abstract Diffusion of transition metals across the cathode–electrolyte interface is identified as a key challenge for the practical realization of solid‐state batteries. This is related to the formation of highly resistive interphases impeding the charge transport across the materials. Herein, the hypothesis that formation of interphases is associated with the incorporation of Co into the Li 7 La 3 Zr 2 O 12 lattice representing the starting point of a cascade of degradation processes is investigated. It is shown that Co incorporates into the garnet structure preferably four‐fold coordinated as Co 2+ or Co 3+ depending on oxygen fugacity. The solubility limit of Co is determined to be around 0.16 per formula unit, whereby concentrations beyond this limit causes a cubic‐to‐tetragonal phase transition. Moreover, the temperature‐dependent Co diffusion coefficient is determined, for example, D 700 °C = 9.46 × 10 −14 cm 2 s −1 and an activation energy E a = 1.65 eV, suggesting that detrimental cross diffusion will take place at any relevant process condition. Additionally, the optimal protective Al 2 O 3 coating thickness for relevant temperatures is studied, which allows to create a process diagram to mitigate any degradation with a minimum compromise on electrochemical performance. This study provides a tool to optimize processing conditions toward developing high energy density solid‐state batteries.

Chemistry↗
DOE OSTI2024

Deconstructing the High Voltage Degradation Mechanisms in Na 2/3 Ni 1/3 Mn 2/3 O 2 with Single Crystals and Advanced Electrolyte

Abstract Sodium layered oxide cathodes can uniquely benefit from the existing lithium‐ion battery industry as sodium‐ion batteries gain traction as a potential low‐cost, drop‐in replacement. However, achieving relevant energy density with a suitable cycle life remains a challenge for sodium layered oxides. At high operating potentials, several competing degradation mechanisms prevent P2‐type Na 2/3 Ni 1/3 Mn 2/3 O 2 (≈550 Wh kg −1 ) from achieving meaningful cycle life—with bulk structural instability and surface reactivity being the primary retractors. Herein, the issue of particle cracking is addressed through detailed synthesis methods of “single‐crystal” materials. By comparison to a polycrystalline baseline, the single‐crystal materials quantify the capacity loss due to isolation of active material caused by intergranular particle cracking. The single crystal materials are then employed in cells with an advanced, “localized saturated electrolyte” (LSE) to demonstrate the magnitude of capacity loss due to electrolyte decomposition at the cathode surface. Mitigation of the surface reactivity through the LSE electrolyte effectively demonstrates the elevated importance of surface reactivity at high voltages despite the onset of egregious particle cracking. This work aims to guide future research into understanding molten‐salt assisted syntheses and advance the debate on surface versus bulk degradation.

Darga, Joe↗
DOE OSTI2022

Unveiling Charge Transport and Degradation Mechanisms of Aqueous Zn|α-MoO 3 Batteries in Conventional Concentration and Water-in-Salt Electrolytes: A Multi-Modal In Situ and Operando Study

Herein charge storage and transport properties are elucidated and cell degradation mechanisms of rechargeable aqueous Zn|alpha-MoO 3 batteries in three electrolyte systems (3 m ZnSO 4 , 3 m ZnCl 2 , and 30 m ZnCl 2 [12.5 m] water-in-salt (WIS)) are distinguished by a combination of in situ X-ray diffraction (XRD), in situ X-ray absorption spectroscopy (XAS), operando optoelectrochemistry, and operando energy dispersive X-ray diffraction (EDXRD). In conventional concentration 3 m electrolytes, in situ XRD and XAS, as well as ex situ scanning transmission electron microscopy data collectively support Zn 2+ as the primary charge carrier. In addition, these systems are susceptible to cathode dissolution, Zn corrosion coupled with the hydrogen evolution reaction, and the resultant formation of basic zinc salt phases. The multi-modal in situ and operando experimental analyses validate facile H+ intercalation and extraction in concentrated 30 m ZnCl 2 WIS electrolyte. Via operando EDXRD, reaction front and charge transport limitation during discharge and charge in the viscous WIS electrolyte are spatially tracked. Here this work provides new insight into the stability and degradation mechanisms of aqueous zinc batteries during static storage and upon dynamic cycling, and highlights the utility of in situ and operando techniques in understanding the superior stability of WIS electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2020

Water Splitting: Emergent Degradation Phenomena Demonstrated on Resilient, Flexible, and Scalable Integrated Photoelectrochemical Cells (Adv. Energy Mater. 48/2020)

We report Photoelectrochemical (PEC) water splitting provides a pathway to generate sustainable clean fuels using the two most abundant resources on Earth: sunlight and water. Currently, most of the successful models of PEC cells are still fabricated on small scales near 1 cm 2 , which largely limits the mass deployment of solar-fuel production. Here, the scale-up to 8 cm 2 of an integrated PEC (IPEC) device is demonstrated and its performance compared to a 1 cm 2 IPEC cell, using state-of-the-art iridium and platinum catalysts with III-V photoabsorbers. The initial photocurrents at 1 sun were 8 and 7 mA cm -2 with degradation rates of 0.60 and 0.47 mA cm -2 day -1 , during unbiased operation for the 1 and 8 cm 2 devices, respectively. Evaluating under outdoor and indoor conditions at two US National Laboratories revealed similar results, evidencing the reproducibility of this design’s performance. Furthermore, the emerging degradation mechanisms during scale-up are investigated and the knowledge gained from this work will provide feedback to the broader community, since PEC device durability is a limiting factor in its potential future deployment.

25 ENERGY STORAGE↗
DOE OSTI2024

Degradation Mechanism of Phosphate‐Based Li‐NASICON Conductors in Alkaline Environment

NASICON-type Li conductors (Li-NASICON) have traditionally been regarded as promising candidates for solid-state Li-air battery applications because of their stability in water and ambient air. However, the presence of water in the cathode of a Li-air battery can induce a highly alkaline environment by modifying the discharge product from Li 2 O 2 to LiOH which can potentially degrade cathode and separator materials. This study investigates the alkaline stability of common Li-NASICON chemistries through a systematic experimental study of LiTi x Ge 2-x (PO 4 ) 3 (LTGP) with varying x = 0–2.0. Density functional theory calculations are combined to gain a mechanistic understanding of the alkaline instability. It is demonstrated that the instability of LTGP in an alkaline environment is mainly driven by the dissolution of PO 4 3– groups, which subsequently precipitate as Li 3 PO 4 . The introduction of Ti facilitates the formation of a Ti-rich compound on the surface that eventually passivates the material, but only after significant bulk degradation. Consequently, phosphate-based Li-NASICON materials exhibit limited alkaline stability, raising concerns about their viability in humid Li-air batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Field‐Relevant Degradation Mechanisms in Metal Halide Perovskite Modules

Field testing, failure analysis, and understanding of degradation mechanisms are essential to advancing metal halide perovskite (MHP) photovoltaic (PV) technology toward commercialization. Here, we present performance data from up to 1 year of outdoor testing of MHP modules in Golden, Colorado. The module encapsulation architecture and encapsulant materials have a significant impact on module reliability, with modules containing a polyolefin elastomer (POE) in addition to a desiccated polyisobutylene (PIB) edge seal outlasting modules with only a PIB edge seal or PIB blanket. Nondestructive and destructive characterization of the field-tested modules points to module scribes and interfaces as areas of potential mechanical weakness and chemical migration, resulting in shunt pathways and increased series resistance. Finally, indoor accelerated stress testing with light and elevated temperatures is performed, demonstrating failure with similar scribe degradation signatures as compared to the field-tested modules. In conclusion, under both outdoor testing and light and elevated temperature conditions, electrochemical corrosion between the copper electrode and the mobile iodine ions appeared dominant, with a significant progression at the scribes that is speculated to result from an interplay between the initial laser damage and joule heating from enhanced ion diffusion under bias.

14 SOLAR ENERGY↗
DOE OSTI2024

Utilization of Novel (KNbO 3 ) 1− x (Ba 2 FeNbO 6 ) x ( x = 0.1, 0.2, 0.3) Solid Solutions for Efficient Photo‐Assisted Fenton Degradation of Methylene Blue Dye

Novel (KNbO 3 ) 1− x (Ba 2 FeNbO 6 ) x ( x = 0.1, 0.2, 0.3) solid solutions corresponding to K 0.82 Ba 0.18 Fe 0.09 Nb 0.91 O 3 , K 0.64 Ba 0.36 Fe 0.18 Nb 0.82 O 3 , and K 0.46 Ba 0.54 Fe 0.27 Nb 0.73 O 3 compounds have been synthesized via molten salt method. X‐ray diffraction confirms the formation of solid solutions, while transmission electron microscopy combined with energy‐dispersive spectroscopy results demonstrates a homogeneous distribution of elements. The obtained solid solutions crystallized in a cubic crystal structure, whereas the parent KNbO 3 possesses an orthorhombic structure. The wide bandgap semiconductor KNbO 3 transformed into a visible‐light‐active material, with its bandgap energy reduced from 3.56 eV to ≈2.4 eV. The substitution of K in KNbO 3 with Ba is responsible for structural modification from orthorhombic to cubic symmetry, whereas both structural modification and the substitution of Nb with Fe correlated with optical properties. The photocatalytic activities of all obtained solid solutions are improved compared with the parent KNbO 3 and Ba 2 FeNbO 6 compounds for photocatalytic degradation of methylene blue (MB) dye. Among the series of solid solutions, K 0.82 Ba 0.18 Fe 0.09 Nb 0.91 O 3 photocatalysts show the highest MB removal efficiency owing to its relatively higher surface area, suppressed charge carrier recombination, and more negative conduction band edge. Moreover, K 0.82 Ba 0.18 Fe 0.09 Nb 0.91 O 3 photocatalyst (0.1 g) combined with hydrogen peroxide (H 2 O 2 ) to form a novel photo‐Fenton system, achieving almost complete degradation of 100 mL of 10 mg L −1 MB dye in 30 min.

Avcıoğlu, Celal [Technische Universität Berlin, Fa↗
DOE OSTI2022

Phase Transfer‐Mediated Degradation of Ether‐Based Localized High‐Concentration Electrolytes in Alkali Metal Batteries

Abstract Localized high‐concentration electrolytes (LHCEs) have attracted interest in alkali metal batteries due to the advantages of forming stable solid‐electrolyte interphases (SEIs) on anodes and good chemical/electrochemical stability. Herein, a new degradation mechanism is revealed for ether‐based LHCEs that questions their compatibility with alkali metal anodes (Li, Na, and K). Specifically, the ether solvent reacts with alkali metals to generate solvated electrons (e s − ) that attack hydrofluoroether co‐solvents to form a series of byproducts. The ether solvent essentially acts as a phase‐transfer reagent that continuously transfers electrons from solid‐phase metals into the solution phase, thus inhibiting the formation of stable SEI and leading to continuous alkali metal corrosion. Switching to an ester‐based solvating solvent or intercalation anodes such as graphite or molybdenum disulfide has been shown to avoid such a degradation mechanism due to the absence of e s − .

Chen, Xiaojuan↗
DOE OSTI2023

Irreparable Interphase Chemistry Degradation Induced by Temperature Pulse in Lithium‐Ion Batteries

Abstract While it is widely recognized that the operating temperature significantly affects the energy density and cycle life of lithium‐ion batteries, the consequence of electrode‐electrolyte interphase chemistry to sudden environmental temperature changes remains inadequately understood. Here, we systematically investigate the effects of a temperature pulse (T pulse) on the electrochemical performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) pouch full cells. By utilizing advanced characterization tools, such as time‐of‐flight secondary‐ion mass spectrometry, we reveal that the T pulse can lead to an irreversible degradation of cathode‐electrolyte interphase chemistry and architecture. Despite negligible immediate impacts on the solid‐electrolyte interphase (SEI) on graphite anode, aggregated cathode‐to‐anode chemical crossover gradually degrades the SEI by catalyzing electrolyte reduction decomposition and inducing metallic dead Li formation because of insufficient cathode passivation after the T pulse. Consequently, pouch cells subjected to the T pulse show an inferior cycle stability to those free of the T pulse. This work unveils the effects of sudden temperature changes on the interphase chemistry and cell performance, emphasizing the importance of a proper temperature management in assessing performance.

Cui, Zehao↗
DOE OSTI2022

Phase Transfer‐Mediated Degradation of Ether‐Based Localized High‐Concentration Electrolytes in Alkali Metal Batteries

Abstract Localized high‐concentration electrolytes (LHCEs) have attracted interest in alkali metal batteries due to the advantages of forming stable solid‐electrolyte interphases (SEIs) on anodes and good chemical/electrochemical stability. Herein, a new degradation mechanism is revealed for ether‐based LHCEs that questions their compatibility with alkali metal anodes (Li, Na, and K). Specifically, the ether solvent reacts with alkali metals to generate solvated electrons (e s − ) that attack hydrofluoroether co‐solvents to form a series of byproducts. The ether solvent essentially acts as a phase‐transfer reagent that continuously transfers electrons from solid‐phase metals into the solution phase, thus inhibiting the formation of stable SEI and leading to continuous alkali metal corrosion. Switching to an ester‐based solvating solvent or intercalation anodes such as graphite or molybdenum disulfide has been shown to avoid such a degradation mechanism due to the absence of e s − .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Irreparable Interphase Chemistry Degradation Induced by Temperature Pulse in Lithium–Ion Batteries

While it is widely recognized that the operating temperature significantly affects the energy density and cycle life of lithium-ion batteries, the consequence of electrode-electrolyte interphase chemistry to sudden environmental temperature changes remains inadequately understood. Here, we systematically investigate the effects of a temperature pulse (T pulse) on the electrochemical performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) pouch full cells. By utilizing advanced characterization tools, such as time-of-flight secondary-ion mass spectrometry, we reveal that the T pulse can lead to an irreversible degradation of cathode-electrolyte interphase chemistry and architecture. Despite negligible immediate impacts on the solid-electrolyte interphase (SEI) on graphite anode, aggregated cathode-to-anode chemical crossover gradually degrades the SEI by catalyzing electrolyte reduction decomposition and inducing metallic dead Li formation because of insufficient cathode passivation after the T pulse. Consequently, pouch cells subjected to the T pulse show an inferior cycle stability to those free of the T pulse. Furthermore, this work unveils the effects of sudden temperature changes on the interphase chemistry and cell performance, emphasizing the importance of a proper temperature management in assessing performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗