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At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Gas Generation Models for Thermal Runaway in Lithium Ion Batteries

A numerical model is implemented to study cell venting, internal pressure, and gas-phase dynamics behavior of Li-ion cells undergoing thermal runaway. A k-ɛ Reynolds-Averaged Navier-Stokes (RANS) model is adopted to describe the turbulent flow out of the cells, while the fluid dynamics inside the cells is described by Darcy-Forchheimer’s equation. Thermal abuse reactions and gas generation kinetics are described by a single-step lumped reaction model. A series of computational fluid dynamics (CFD) simulations are conducted on a single cell at various states-of-charge (100%, 50%, 25%) to demonstrate detailed flow and thermal behavior as a function of quantity of gas generated during cell venting. Venting events are categorized into two stages: i) breaching of the cell container and ii) thermal runaway reactions. It is shown that the cell response is dominated by the second stage since most of the gases are generated during thermal runaway. Also, the propensity for propagation is highly affected by state-of-charge (SOC). Cells at higher SOCs produce more heat and gas during the venting event, owing to higher mass and concentrations of reacting gases, and consequently reach higher internal cell pressures which increase the risk of side-wall breaching.

Kim, Jinyong↗

NASA NTRS2007

Performance of Low Temperature Electrolytes in Experimental and Prototype Li-Ion Cells

Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with ethylene carbonate-based electrolytes optimized for low temperature in experimental MCMB-LiNixCo1_x0 2 cells. In addition to obtaining discharge and charge rate performance data at various temperatures, electrochemical measurements were performed on individual electrodes (made possible by the incorporation of Li reference electrodes), including EIS, linear polarization and Tafel polarization measurements. The combination of techniques enables the elucidation of various trends associated with electrolyte composition. In addition to investigating the behavior in experimental cells, the performance of many promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

Li-ion batteries↗

NASA NTRS1977

Self discharge of nickel-hydrogen cells

Values for the capacity loss with time, naturally on open circuit stand, and information regarding the minimum amount of circuit charge needed to keep the cell charged can be determined from the self-discharge behavior of nickel hydrogen cells. Furthermore, the rate of reaction between hydrogen and a charged nickel electrode is also open for nickel cadmium batteries. In a nickel hydrogen cell, the hydrogen is stored as pressurized gas and the cell stack with the charge that is oxidized nickel-hydroxide electrode is in direct contact with the hydrogen. Therefore, the rate of reaction can be measured easily and precisely by monitoring the charge, the change in hydrogen pressure with time. Measures made on twelve 15 ampere hour nickel hydrogen cells of different stack configurations built for COMSAT are discussed.

Holleck, G.↗

NASA NTRS1987

Solar cell design for avoiding LILT degradation

Growing concerns about radioisotope thermoelectric generator (RTG) performance potential, cost, safety, and availability have renewed interest in utilizing photovoltaic energy conversion for future JPL interplanetary missions such as the Mariner Mark II set. Although lightweight solar array technology has advanced to the point where it would appear to provide an alternative power source, anomalous silicon cell curve shape degradation at conditions of low intensity and low temperature (LILT) severely restricts photovoltaic applications for missions beyond 3 AU solar distance. In order to extend photovoltaic applications to distances of 5 AU, ways to minimize the deleterious impact of LILT cell degradation were investigated. These investigations have ranged from consideration of individual cell selection for LILT behavior to the examination of methods for reducing or eliminating cell LILT degradation by modifying the cell processing. Use of a partial oxide barrier between the cell n+ contacts and the silicon has been shown to reduce significantly both the occurrence and magnitude of the LILT degradation.

Stella, P. M.↗

NASA NTRS1991

Hubble Space Telescope nickel-hydrogen flight spare battery test

For several years, MSFC has been engaged in a series of battery tests in support of the Hubble Space Telescope (HST) Program. Now that the HST is in orbit, many of these tests will continue in order to give those responsible for the HST a reasonable prediction on the performance of the flight batteries. These tests will also be a source of needed low earth orbit (LEO) data for nickel hydrogen (Ni-H2) batteries and cells. One of the tests currently in progress at MSFC is a mission simulation test on a 22-cell Ni-H2 battery. This battery is composed of spare cells taken from the lot of cells out of which the Flight Spare Module was assembled. This module is one of two modules launched on the HST. This battery has been on test since Jun. 1989 and has completed nearly 8000 LEO cycles. A series of characterization tests were run prior to the start of the mission simulation and a launch scenario test was run in Feb. and Mar. 1990 to test the behavior of the cells through a simulated launch. The results from these tests as well as the overall performance of the battery as it continues to cycle are reported.

Brewer, Jeffrey C.↗

NASA NTRS2002

Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation

The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.

NASA Discipline Musculoskeletal↗

NASA NTRS1971

Kinetics in solar cell damage

Reaction kinetics model for electrical behavior of irradiated Li-doped solar cells

Sosin, A.↗

DOE OSTI2024

Evaluating Pressure‐dependent Discharge Behavior of Foil Versus In situ Plated Lithium Metal Anodes in Solid‐State Batteries

Abstract Anode‐free manufacturing of solid‐state batteries (SSBs) shows promise to maximize energy density by eliminating excess lithium (Li) and simplifying battery production. However, high reversibility during discharge (stripping of Li) is necessary for long‐lifetime SSBs with a limited Li reservoir. Further, the plastic flow of Li changes depending on the Li thickness, leading to possible differences in discharge performance under stack pressure. This work investigates the pressure‐dependent discharge performance of anode‐free manufactured SSBs with in situ plated Li and compares the performance to that of conventional thick Li foil cells. Distinct stripping behavior is observed at low pressures (0–1 MPa), where Li diffusivity and initial interfacial contact may control accessible capacity, compared to high pressures (3–10 MPa) where mechanical deformation of Li likely governs stripping behavior. Analysis of impedance spectra collected during stripping shows that additional stack pressure delays the formation of deep, as opposed to lateral, voids in the Li anode. These results provide insights to guide the transition from thick Li foil anodes to anode‐free manufactured SSBs.

Haslam, Catherine G.↗

DOE OSTI2023

Origin of Rapid Delithiation In Secondary Particles Of LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiNi y Mn z Co 1− y − z O 2 Cathodes

Abstract Most research on the electrochemical dynamics in materials for high‐energy Li‐ion batteries has focused on the global behavior of the electrode. This approach is susceptible to misleading analyses resulting from idiosyncratic kinetic conditions, such as surface impurities inducing an apparent two‐phase transformation within LiNi 0.8 Co 0.15 Al 0.05 O 2 . Here, nano‐focused X‐ray probes are used to measure delithiation operando at the scale of secondary particle agglomerates in layered cathode materials during charge. After an initial latent phase, individual secondary particles undergo rapid, stochastic, and largely uniform delithiation, which is in contrast with the gradual increase in cell potential. This behavior reproduces across several layered oxides. Operando X‐ray microdiffraction (‐XRD) leverages the relationship between Li content and lattice parameter to further reveal that rate acceleration occurs between Li‐site fraction ( x Li ) ≈0.9 and ≈0.5 for LiNi 0.8 Co 0.15 Al 0.05 O 2 . Physics‐based modeling shows that, to reproduce the experimental results, the exchange current density ( i 0 ) must depend on x Li , and that i 0 should increase rapidly over three orders of magnitude at the transition point. The specifics and implications of this jump in i 0 are crucial to understanding the charge‐storage reaction of Li‐ion battery cathodes.

25 ENERGY STORAGE↗

DOE OSTI2023

PACT Perovskite PV Module Outdoor Test Protocol (Version 0.1)

The purpose of this protocol is to define procedures and practices to be used by the PACT center for field testing of metal halide perovskite (MHP) photovoltaic (PV) modules. The protocol defines the physical, electrical, and analytical configuration of the tests and applies equally to mounting systems at a fixed orientation or sun tracking systems. While standards exist for outdoor testing of conventional PV modules, these do not anticipate the unique electrical behavior of perovskite cells. Further, the existing standards are oriented toward mature, relatively stable products with lifetimes that can be measured on the scale of years to decades. The state of the art for MHP modules is still immature with considerable sample to sample variation among nominally identical modules. Version 0.0 of this protocol does not define a minimum test duration, although the intent is for modules to be fielded for periods ranging for weeks to months. This protocol draws from relevant parts of existing standards, and where necessary includes modifications specific to the behavior of perovskites.

14 SOLAR ENERGY↗

DOE OSTI2025

PACT Perovskite PV Module Outdoor Test Protocol (Version 0.2)

14 SOLAR ENERGY↗

DOE OSTI2023

Crack Growth Rate at Oxygen Electrode/Electrolyte Interface in Solid Oxide Electrolysis Cells Predicted by Experiment Coupled Multiphysics Modeling

Solid oxide electrolysis cell (SOEC) is a very efficient hydrogen production technology, but the cell degradation is a serious limiting factor for its long-term implementation. Oxygen electrode (OE) delamination is reported to be the critical degradation mechanism. In this study, we present a methodology to understand the delamination failure of the OE due to chemical stress in a better perspective. Several OE configurations were tested: baseline strontium-doped lanthanum cobalt iron oxide (LSCF) single layer design and tantalum-doped strontium cobalt oxide (SCT) - LSCF bilayer designs with different SCT loadings. An electro-chemo-mechanical model is developed to associate the electrochemical behavior of the cell with solid mechanics for calculating crack growth of the cell during long term test. The bilayer configuration with SCT 20 wt% has better performance as it survived in the long-term life test with the least crack length. This study implies that an additional nano-coating of SCT over the OE have improved the species transport and oxygen evolution with reduced chemical stress. As the operating current density decreases, it takes longer time for the cell to reach the delamination with the same critical crack length of 6.5 μ m (∼93% of the electrode/electrolyte interface length). Finally, it was concluded that chemical stress plays a significant role in interface delamination failure, however it may not be the only source of stresses at the interface.

08 HYDROGEN↗

DOE OSTI2022

Explosion behavior investigation and safety assessment of large-format lithium-ion pouch cells

We report large-format lithium-ion (Li-ion) batteries with high energy density for electric vehicles are prone to thermal runaway (or even explosion) under abusive conditions. In this study, overcharge induced explosion behaviors of large-format Li-ion pouch cells with Li[Ni 0.8 Co 0.1 Mn 0.1 ]O 2 cathode at different current rates (C-rates) (0.5C, 1C, 2C) were investigated. The explosion characteristics of the cells were elucidated by discussing the evolution of the cell voltage, the surface temperature and the shock wave pressure. Generally, the whole overcharge process could be divided into four stages according to the evolution of several key parameters and the overcharge behaviors; the overcharge C-rate has a great influence on cells’ thermal behaviors. The experimental results showed that the thermal runaway process of Li-ion cells caused by overcharging consisted of two kinds of explosions, physical explosion and chemical explosion. The existence of observable negative pressure zone in the pressure curves indicated that the Li-ion cells are not a self-supplying oxygen system during the explosion. Further, the explosion dynamics parameters were matched. An explosion TNT-equivalent conversion strategy that depended on the pressure of the shock wave was utilized to evaluate the released energy and its hazards. In addition, with respect to the overcharge of Li-ion pouch cells, a safety assessment method and a safety management method were proposed based on the explosion behaviors. From the perspective of battery safety, this study is of great significance for the safety design of Li-ion cells and can provide guidance for engineers to optimize the safety function of battery packs.

25 ENERGY STORAGE↗

NASA NTRS1990

1.00 MeV proton radiation resistance studies of single-junction and single gap dual-junction amorphous-silicon alloy solar cells

A comparative study of the radiation resistance of a-Si:H and a-SiGe:H single-junction and a-Si:H dual-junction solar cells was conducted. The cells were irradiated with 1.00-MeV protons with fluences of 1.0 x 10 to the 14th, 5.0 x 10 to the 14th and 1.0 x 10 to the 15th/sq cm and characterized using I-V and quantum efficiency measurements. The radiation resistance of single-junction cells cannot be used to explain the behavior of dual-junction cells at a fluence of 1.0 x 10 to the 15th/sq cm. The a-Si H single-junction cells degraded the least of the three cells; a-SiGe:H single-junction cells showed the largest reduction in short-circuit current, while a-Si:H dual-junction cells exhibited the largest degradation in the open-circuit voltage. The quantum efficiency of the cells degraded more in the red part of the spectrum; the bottom junction degrades first in dual-junction cells.

Abdulaziz, Salman↗

NASA NTRS1995

Probing transmembrane mechanical coupling and cytomechanics using magnetic twisting cytometry

We recently developed a magnetic twisting cytometry technique that allows us to apply controlled mechanical stresses to specific cell surface receptors using ligand-coated ferromagnetic microbeads and to simultaneously measure the mechanical response in living cells. Using this technique, we have previously shown the following: (i) beta 1 integrin receptors mediate mechanical force transfer across the cell surface and to the cytoskeleton, whereas other transmembrane receptors (e.g., scavenger receptors) do not; (ii) cytoskeletal stiffness increases in direct proportion to the level of stress applied to integrins; and (iii) the slope of this linear stiffening response differs depending on the shape of the cell. We now show that different integrins (beta 1, alpha V beta 3, alpha V, alpha 5, alpha 2) and other transmembrane receptors (scavenger receptor, platelet endothelial cell adhesion molecule) differ in their ability to mediate force transfer across the cell surface. In addition, the linear stiffening behavior previously observed in endothelial cells was found to be shared by other cell types. Finally, we demonstrate that dynamic changes in cell shape that occur during both cell spreading and retraction are accompanied by coordinate changes in cytoskeletal stiffness. Taken together, these results suggest that the magnetic twisting cytometry technique may be a powerful and versatile tool for studies analyzing the molecular basis of transmembrane mechanical coupling to the cytoskeleton as well as dynamic relations between changes in cytoskeletal structure and alterations in cell form and function.

NASA Discipline Number 40-20↗

DOE OSTI2024

Polysulfide-incompatible additive suppresses spatial reaction heterogeneity of Li-S batteries

Rational electrolyte engineering for practical pouch cells remains elusive because the correlation between the cathode/solid-electrolyte interphase layer and cell-level reaction behavior is poorly understood. Here, by combining multiscale characterization and computational modeling, we show that—counter to the conventional perception of polysulfide-incompatible additives—the spontaneous reaction of sparingly solvated polysulfides with Lewis acid additives (LAAs) can induce in situ formation of a homogeneous interphase on thick and tortuous S cathode. Multiscale synchrotron X-ray characterization consistently affirms that such interface design could effectively eliminate the notorious problems of polysulfide shuttle and lithium corrosion and, more importantly, provide an interconnected “ion transport highway” to alleviate the uneven ion transport within the tortuous S cathode. Hence, this design dramatically reduces the reaction heterogeneity of lithium-sulfur (Li-S) pouch cells under lean electrolyte conditions. Further, this work resolves controversy around the role of polysulfide-incompatible additives in high-energy Li-S pouch cells and highlights the importance of suppressing reaction heterogeneity for practical batteries.

36 MATERIALS SCIENCE↗

NASA NTRS2001

Spatiotemporal relationships between growth and microtubule orientation as revealed in living root cells of Arabidopsis thaliana transformed with green-fluorescent-protein gene construct GFP-MBD

Arabidopsis thaliana plants were transformed with GFP-MBD (J. Marc et al., Plant Cell 10: 1927-1939, 1998) under the control of a constitutive (35S) or copper-inducible promoter. GFP-specific fluorescence distributions, levels, and persistence were determined and found to vary with age, tissue type, transgenic line, and individual plant. With the exception of an increased frequency of abnormal roots of 35S GFP-MBD plants grown on kanamycin-containing media, expression of GFP-MBD does not appear to affect plant phenotype. The number of leaves, branches, bolts, and siliques as well as overall height, leaf size, and seed set are similar between wild-type and transgenic plants as is the rate of root growth. Thus, we conclude that the transgenic plants can serve as a living model system in which the dynamic behavior of microtubules can be visualized. Confocal microscopy was used to simultaneously monitor growth and microtubule behavior within individual cells as they passed through the elongation zone of the Arabidopsis root. Generally, microtubules reoriented from transverse to oblique or longitudinal orientations as growth declined. Microtubule reorientation initiated at the ends of the cell did not necessarily occur simultaneously in adjacent neighboring cells and did not involve complete disintegration and repolymerization of microtubule arrays. Although growth rates correlated with microtubule reorientation, the two processes were not tightly coupled in terms of their temporal relationships, suggesting that other factor(s) may be involved in regulating both events. Additionally, microtubule orientation was more defined in cells whose growth was accelerating and less stringent in cells whose growth was decelerating, indicating that microtubule-orienting factor(s) may be sensitive to growth acceleration, rather than growth per se.

NASA Discipline Plant Biology↗

NASA NTRS2008

Assessment of Various Low Temperature Electrolytes in Prototype Li-Ion Cells Developed for ESMD Applications

Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with six different ethylene carbonate-based electrolytes optimized for low temperature. In addition to investigating the behavior in experimental cells initially, the performance of these promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells, manufactured by Yardney Technical Products and Saft America, Inc. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

Wide Operating Temperature Electrolytes↗