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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

In Situ Li Seed Formation Enables Uniform Plating in Anode-Free Solid-State Batteries

Anode-free solid-state batteries (AFSSBs) are a promising route toward achieving high energy density. In these cells, the anode contains no pre-stored lithium (Li). Instead, all Li inventory originates from the cathode and is freshly deposited onto a bare current collector during charging. However, achieving uniform and defect-free Li plating on this bare current collector remains a major challenging, often resulting in low Li plating/stripping efficiency and rapid capacity decay. Here, for the first time, operando neutron imaging is employed to visualize Li plating/stripping behavior in an anode-free full cell with LiNi 0.82 Mn 0.07 Co 0.11 O 2 (NMC) as the cathode. Operando measurements reveal that complete stripping of Li leaves isolated Li residues on the current collector, which degrades interfacial contact between the current collector and solid-state electrolyte. To mitigate this interfacial issue and promote more uniform Li deposition, we implement a discharge cutoff voltage strategy that intentionally retains a thin residual Li layer after stripping. This thin Li layer, serving as an in situ–formed seed layer, not only enables more homogeneous subsequent Li plating but also improves interfacial contact. As a result, the anode-free cell with a controlled discharge voltage of 3.5 V exhibits excellent long-term cycling stability, maintaining a discharge capacity of 116 mAh g -1 with a retention rate of 83.4% and an average Coulombic efficiency of approximately 99.9% after 430 cycles at 0.25 C. In contrast, the cell with a conventional discharge cutoff voltage of 2.8 V exhibits rapid capacity decay, retaining only 59.7 mAh g -1 after 50 cycles with a capacity retention of 40.7%. This work offers a practical strategy to unlock the long-term viability of anode-free solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Keratin Promotes Differentiation of Keratinocytes Seeded on Collagen/Keratin Hydrogels

Keratinocytes undergo a complex process of differentiation to form the stratified stratum corneum layer of the skin. In most biomimetic skin models, a 3D hydrogel fabricated out of collagen type I is used to mimic human skin. However, native skin also contains keratin, which makes up 90% of the epidermis and is produced by the keratinocytes present. We hypothesized that the addition of keratin (KTN) in our collagen hydrogel may aid in the process of keratinocyte differentiation compared to a pure collagen hydrogel. Keratinocytes were seeded on top of a 100% collagen or 50/50 C/KTN hydrogel cultured in either calcium-free (Ca-free) or calcium+ (Ca+) media. Our study demonstrates that the addition of keratin and calcium in the media increased lysosomal activity by measuring the glucocerebrosidase (GBA) activity and lysosomal distribution length, an indication of greater keratinocyte differentiation. We also found that the presence of KTN in the hydrogel also increased the expression of involucrin, a differentiation marker, compared to a pure collagen hydrogel. We demonstrate that a combination (i.e., containing both collagen and kerateine or “C/KTN”) hydrogel was able to increase keratinocyte differentiation compared to a pure collagen hydrogel, and the addition of calcium further increased the differentiation of keratinocytes. This multi-protein hydrogel shows promise in future models or treatments to increase keratinocyte differentiation into the stratum corneum.

Zuniga, Kameel (ORCID:0000000196674007)↗
DOE OSTI2017

Neutron-decay Protons from Solar Flares as Seed Particles for CME-shock Acceleration in the Inner Heliosphere

The protons in large solar energetic particle events are accelerated in the inner heliosphere by fast shocks produced by coronal mass ejections. Unless there are other sources, the protons these shocks act upon would be those of the solar wind (SW). The efficiency of the acceleration depends on the kinetic energy of the protons. For a 2000 km s{sup −1} shock, the most effective proton energies would be 30–100 keV; i.e., within the suprathermal tail component of the SW. We investigate one possible additional source of such protons: those resulting from the decay of solar-flare-produced neutrons that escape from the Sun into the low corona. The neutrons are produced by interactions of flare-accelerated ions with the solar atmosphere. We discuss the production of low-energy neutrons in flares and their decay on a interplanetary magnetic field line near the Sun. We find that even when the flaring conditions are optimal, the 30–100 keV neutron-decay proton density produced by even a very large solar flare would be only about 10% of that of the 30–100 keV SW suprathermal tail. We discuss the implication of a seed-particle source of more frequent, small flares.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Seeding Supermassive Black Holes with Self-interacting Dark Matter: A Unified Scenario with Baryons

Observations show that supermassive black holes (SMBHs) with a mass of ~10 9 M ⊙ exist when the universe is just 6% of its current age. We propose a scenario where a self-interacting dark matter halo experiences gravothermal instability and its central region collapses into a seed black hole. The presence of baryons in protogalaxies could significantly accelerate the gravothermal evolution of the halo and shorten collapse timescales. The central halo could dissipate its angular momentum remnant via viscosity induced by the self-interactions. The host halo must be on high tails of density fluctuations, implying that high-z SMBHs are expected to be rare in this scenario. We further derive conditions for triggering general relativistic instability of the collapsed region. Furthermore, our results indicate that self-interacting dark matter can provide a unified explanation for diverse dark matter distributions in galaxies today and the origin of SMBHs at redshifts z ~ 6–7.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors

The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N2) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes >40 MW/m2 down to <10 MW/m2 while maintaining excellent core confinement, H98>1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. These considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗