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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Li2ZnSi by Materials Project

Li2ZnSi crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Li1+ is bonded in a 5-coordinate geometry to one Li1+, one Zn2+, and three equivalent Si4- atoms. The Li–Li bond length is 2.45 Å. The Li–Zn bond length is 2.48 Å. All Li–Si bond lengths are 2.56 Å. Zn2+ is bonded in a linear geometry to two equivalent Li1+ atoms. Si4- is bonded in a distorted hexagonal planar geometry to six equivalent Li1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSiAg2 by Materials Project

LiAg2Si crystallizes in the cubic F-43m space group. The structure is three-dimensional. Li1+ is bonded in a body-centered cubic geometry to four equivalent Ag+1.50+ and four equivalent Si4- atoms. All Li–Ag bond lengths are 2.76 Å. All Li–Si bond lengths are 2.76 Å. There are two inequivalent Ag+1.50+ sites. In the first Ag+1.50+ site, Ag+1.50+ is bonded in a body-centered cubic geometry to four equivalent Ag+1.50+ and four equivalent Si4- atoms. All Ag–Ag bond lengths are 2.76 Å. All Ag–Si bond lengths are 2.76 Å. In the second Ag+1.50+ site, Ag+1.50+ is bonded in a 4-coordinate geometry to four equivalent Li1+ and four equivalent Ag+1.50+ atoms. Si4- is bonded in a distorted body-centered cubic geometry to four equivalent Li1+ and four equivalent Ag+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiYSi by Materials Project

LiYSi crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Li1+ is bonded to four Si4- atoms to form LiSi4 tetrahedra that share corners with six equivalent YSi5 square pyramids, corners with ten equivalent LiSi4 tetrahedra, edges with six equivalent YSi5 square pyramids, and edges with two equivalent LiSi4 tetrahedra. There are two shorter (2.67 Å) and two longer (2.77 Å) Li–Si bond lengths. Y3+ is bonded to five Si4- atoms to form YSi5 square pyramids that share corners with ten equivalent YSi5 square pyramids, corners with six equivalent LiSi4 tetrahedra, edges with six equivalent YSi5 square pyramids, and edges with six equivalent LiSi4 tetrahedra. There are four shorter (2.98 Å) and one longer (2.99 Å) Y–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to six equivalent Li1+ and three equivalent Y3+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to three equivalent Li1+ and six equivalent Y3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li7Si2 by Materials Project

Li7Si2 is zeta silver zinc-like structured and crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are eight inequivalent Li sites. In the first Li site, Li is bonded in a 4-coordinate geometry to two equivalent Li and four equivalent Si atoms. Both Li–Li bond lengths are 2.95 Å. All Li–Si bond lengths are 2.57 Å. In the second Li site, Li is bonded in a body-centered cubic geometry to eight Li atoms. There are two shorter (2.36 Å) and six longer (2.65 Å) Li–Li bond lengths. In the third Li site, Li is bonded in a 3-coordinate geometry to five Li and three Si atoms. There are a spread of Li–Li bond distances ranging from 2.38–2.78 Å. There are one shorter (2.53 Å) and two longer (2.66 Å) Li–Si bond lengths. In the fourth Li site, Li is bonded in a 10-coordinate geometry to two Li and four Si atoms. The Li–Li bond length is 2.73 Å. There are a spread of Li–Si bond distances ranging from 2.70–2.91 Å. In the fifth Li site, Li is bonded in a 3-coordinate geometry to seven Li and three Si atoms. There are two shorter (2.70 Å) and two longer (2.88 Å) Li–Li bond lengths. There are one shorter (2.67 Å) and two longer (2.73 Å) Li–Si bond lengths. In the sixth Li site, Li is bonded in a 2-coordinate geometry to three Li and four Si atoms. The Li–Li bond length is 2.49 Å. There are a spread of Li–Si bond distances ranging from 2.65–2.97 Å. In the seventh Li site, Li is bonded in a 2-coordinate geometry to four Li and two equivalent Si atoms. There are one shorter (2.61 Å) and one longer (2.62 Å) Li–Li bond lengths. There are one shorter (2.69 Å) and one longer (2.72 Å) Li–Si bond lengths. In the eighth Li site, Li is bonded in a 12-coordinate geometry to eight Li and four Si atoms. There are a spread of Li–Si bond distances ranging from 2.82–2.96 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 12-coordinate geometry to twelve Li atoms. In the second Si site, Si is bonded in a 11-coordinate geometry to ten Li and one Si atom. The Si–Si bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2SiAu by Materials Project

Li2AuSi crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form corner-sharing LiSi4 tetrahedra. All Li–Si bond lengths are 2.64 Å. In the second Li1+ site, Li1+ is bonded to four equivalent Au2+ atoms to form distorted corner-sharing LiAu4 tetrahedra. All Li–Au bond lengths are 2.64 Å. Au2+ is bonded in a body-centered cubic geometry to four equivalent Li1+ and four equivalent Si4- atoms. All Au–Si bond lengths are 2.64 Å. Si4- is bonded in a body-centered cubic geometry to four equivalent Li1+ and four equivalent Au2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(SiRh)2 by Materials Project

Li(RhSi)2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Li1+ is bonded in a square co-planar geometry to four equivalent Si4- atoms. All Li–Si bond lengths are 2.70 Å. Rh+3.50+ is bonded in a 6-coordinate geometry to six equivalent Si4- atoms. There are two shorter (2.46 Å) and four longer (2.50 Å) Rh–Si bond lengths. Si4- is bonded in a 8-coordinate geometry to two equivalent Li1+ and six equivalent Rh+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaLi2(MgSi)2 by Materials Project

Li2Ba(MgSi)2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Li1+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Li–Si bond lengths are 2.65 Å. Ba2+ is bonded to six equivalent Si4- atoms to form BaSi6 octahedra that share corners with eighteen equivalent MgSi4 tetrahedra, edges with six equivalent BaSi6 octahedra, and faces with two equivalent MgSi4 tetrahedra. All Ba–Si bond lengths are 3.56 Å. Mg2+ is bonded to four equivalent Si4- atoms to form MgSi4 tetrahedra that share corners with nine equivalent BaSi6 octahedra, corners with six equivalent MgSi4 tetrahedra, edges with three equivalent MgSi4 tetrahedra, and a faceface with one BaSi6 octahedra. The corner-sharing octahedra tilt angles range from 48–52°. There are one shorter (2.78 Å) and three longer (2.89 Å) Mg–Si bond lengths. Si4- is bonded in a 10-coordinate geometry to three equivalent Li1+, three equivalent Ba2+, and four equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSiNi2 by Materials Project

LiNi2Si is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Li1+ is bonded in a 8-coordinate geometry to eight equivalent Ni+1.50+ and six equivalent Si4- atoms. All Li–Ni bond lengths are 2.40 Å. All Li–Si bond lengths are 2.77 Å. Ni+1.50+ is bonded in a distorted body-centered cubic geometry to four equivalent Li1+ and four equivalent Si4- atoms. All Ni–Si bond lengths are 2.40 Å. Si4- is bonded in a 8-coordinate geometry to six equivalent Li1+ and eight equivalent Ni+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2MgSi by Materials Project

Li2MgSi is alpha bismuth trifluoride-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional and consists of four lithium molecules and one LiMgSi framework. In the LiMgSi framework, Li1+ is bonded to four equivalent Si4- atoms to form LiSi4 tetrahedra that share corners with four equivalent MgSi4 tetrahedra, corners with twelve equivalent LiSi4 tetrahedra, and edges with six equivalent MgSi4 tetrahedra. All Li–Si bond lengths are 2.76 Å. Mg2+ is bonded to four equivalent Si4- atoms to form MgSi4 tetrahedra that share corners with four equivalent LiSi4 tetrahedra, corners with twelve equivalent MgSi4 tetrahedra, and edges with six equivalent LiSi4 tetrahedra. All Mg–Si bond lengths are 2.76 Å. Si4- is bonded in a body-centered cubic geometry to four equivalent Li1+ and four equivalent Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Mitigating Calendar Aging in Si-NMC Batteries with Advanced Dual-Salt Glyme Electrolytes

In addressing the critical challenge of calendar aging in silicon (Si)-based lithium-ion batteries, this study introduces a groundbreaking strategy utilizing glyme-type dual-salt electrolytes (lithium bis(trifluoromethanesulfonyl)imide [LiTFSI] and lithium difluoro(oxalato)borate [LiDFOB]). These electrolytes are demonstrated to significantly mitigate parasitic reactions and capacity loss in Si-NMC (lithium nickel manganese cobalt oxide) full cells, especially when compared with traditional carbonate-based electrolytes. Further, our exhaustive mechanistic analysis reveals that such electrolytes not only preserve the integrity of the Si anode but also improve the cathode/electrolyte interphases (CEI) through the formation of a conformal coating on the high-voltage cathode surface. This dual-salt approach, enhanced by the addition of a phosphate additive, effectively decelerates calendar aging, marking a substantial advance in the quest for durable and reliable Si-based energy storage technologies. The findings underscore the vital role of electrolyte composition in extending the calendar life of Si batteries, offering an alternative avenue toward maximizing the performance and longevity of next-generation Li-Si batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Experimental considerations and applications for time-resolved impedance on silicon-anode battery systems

Dynamic electrochemical impedance spectroscopy (dEIS) utilizes a superimposed multi-sinusoidal waveform and enables temporally resolved investigations on various electrochemical processes; however, the signal-to-noise ratio must be maximized while retaining linearity and stationarity within the system. In the present work, we probe the impact of the waveform’s total amplitude as well as the waveform and phase profiles. The equal amplitude multi-sinusoidal waveform with 35 mV total amplitude (<1 mV per frequency) and random phase profile exhibits the lowest impedance noise. This input signal is sufficient in avoiding the high frequency signal attenuation from the potentiostat’s low-pass filter. Additionally, we demonstrate the optimized dEIS waveform’s utility in investigating surface passivation within thin-film and composite silicon (Si) anodes. Within a two-electrode Si-lithium metal coin cell, the charge transfer resistance (RCT) associated with alloying kinetics dominates the overall impedance. RCT increases with state of charge indicating a kinetic bottleneck at higher lithiation states. To explore this further, we utilize a three-electrode Si-LiNi0.8Mn0.1Co0.1O2 pouch cell to deconvolute the Si impedance contributions. The evolution of the solid electrolyte interphase (SEI) and charge transfer resistances correlate to specific Li–Si alloy phases. We attribute this to the influence of Si particle volume expansion on SEI instabilities and a kinetic bottleneck at higher lithiation states.

Lam, Steven [ORNL]↗
DOE OSTI2021

Review—The Lithiation/Delithiation Behavior of Si-Based Electrodes: A Connection between Electrochemistry and Mechanics

Silicon is a promising alternative anode material to graphite because of its high gravimetric and volumetric energy densities. However, severe capacity fading is observed in Si electrodes, and it is a result of mechanical changes of Si, such as volume changes, stress or fracture. Furthermore, these mechanical behaviors are strongly coupled with the electrochemistry of the Li-Si alloying reaction in Si-based electrodes, including both thermodynamics and kinetics. Therefore, the electrochemical properties of Si-based electrodes are strongly dependent on the control of the mechanics of Si during lithiation/delithiation. As such, it is very important to understand the correlation between electrochemistry and mechanics. Here, we review lithiation/delithiation behaviors of various types of Si-based electrodes, applying a fundamental understanding of electrochemistry and mechanics and the correlation between them.

25 ENERGY STORAGE↗
DOE OSTI2026

Mass spectral molecular mapping shows benefits of thermal evaporation in prelithiated silicon-based electrodes

Silicon based composites have become increasingly popular as potential anodes for lithium-ion batteries due to their large storage capacity and potential ability to generate batteries with energy densities greater than 350 Wh kg −1 . These anodes often see reduced initial columbic efficiency (ICE) due to disruptive volume expansionup to 300% and continuous solid electrolyte interphase (SEI) layer formation. Prelithiation, where an excess reservoir of Li is added to the electrode to compensate for irreversible SEI formation losses during their sample preparation, has proven to solve the issue of immediate capacity loss. Thermal evaporation is a prelithiation technique with limited studies on its effectiveness. In this study, time-of-flight secondary ion mass spectrometry (ToF-SIMS) is used to highlight the benefits of prelithiation via thermal evaporation. ToF-SIMS provides chemical mapping and spatial information in 2D and 3D visualizing the deposition of lithium, identifying Li x Si y alloy and Li x Si y O z silicate formation, and the distribution of lithium passivation into the electrodes. Passivation under different atmospheric conditions, such as inert Argon (Ar) and Ar/ carbon dioxide (CO 2 ), highlights the impact of the environment on the passivation effectiveness and formation of Li x Si y alloy and Li x Si y O z silicate. The ToF-SIMS molecular imaging and depth profiling results indicate that prelithiation via thermal evaporation effectively distributes lithium throughout the depth profile thickness of several hundred nanometers. It induces a greater degree of Li x Si y O z silicate formation over Li x Si y alloy. Our ToF-SIMS characterization results show the effectiveness of thermal evaporation in producing a more stable electrode and an electrode with an effective lithium reserve that can preserve its capacity.

Parker, Gabriel D. [Oak Ridge National Laboratory ↗
DOE OSTI2020

Materials Data on Li7Si3 by Materials Project

Li7Si3 crystallizes in the trigonal P3_212 space group. The structure is three-dimensional. there are eight inequivalent Li sites. In the first Li site, Li is bonded in a 10-coordinate geometry to eight Li and six Si atoms. There are a spread of Li–Li bond distances ranging from 2.70–2.74 Å. There are two shorter (3.04 Å) and four longer (3.09 Å) Li–Si bond lengths. In the second Li site, Li is bonded in a 10-coordinate geometry to eight Li and six Si atoms. There are a spread of Li–Li bond distances ranging from 2.71–2.74 Å. There are a spread of Li–Si bond distances ranging from 3.04–3.10 Å. In the third Li site, Li is bonded in a 4-coordinate geometry to three Li and four Si atoms. The Li–Li bond length is 2.58 Å. There are a spread of Li–Si bond distances ranging from 2.56–2.83 Å. In the fourth Li site, Li is bonded in a 3-coordinate geometry to two Li and four Si atoms. Both Li–Li bond lengths are 2.66 Å. There are a spread of Li–Si bond distances ranging from 2.68–3.03 Å. In the fifth Li site, Li is bonded to two Li and four Si atoms to form a mixture of distorted face and corner-sharing LiLi2Si4 tetrahedra. There are a spread of Li–Si bond distances ranging from 2.63–2.81 Å. In the sixth Li site, Li is bonded in a 3-coordinate geometry to five Li and six Si atoms. There are a spread of Li–Li bond distances ranging from 2.58–2.62 Å. There are a spread of Li–Si bond distances ranging from 2.62–2.95 Å. In the seventh Li site, Li is bonded in a 4-coordinate geometry to three Li and four Si atoms. There are a spread of Li–Si bond distances ranging from 2.56–2.81 Å. In the eighth Li site, Li is bonded in a 3-coordinate geometry to five Li and six Si atoms. The Li–Li bond length is 2.62 Å. There are a spread of Li–Si bond distances ranging from 2.62–2.94 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded in a 7-coordinate geometry to eleven Li atoms. In the second Si site, Si is bonded in a 8-coordinate geometry to twelve Li and one Si atom. The Si–Si bond length is 2.35 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to eleven Li atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Twisted Supergravity and Koszul Duality: A Case Study in AdS 3

In this note, we study a simplified variant of the familiar holographic duality between supergravity on AdS 3 × S 3 × T 4 and the SCFT (on the moduli space of) the symmetric orbifold theory Sym N (T 4 ) as N → ∞. This variant arises conjecturally from a twist proposed by the first author and Si Li. We recover a number of results concerning protected subsectors of the original duality working directly in the twisted bulk theory. Moreover, we identify the symmetry algebra arising in the N → ∞ limit of the twisted gravitational theory. Further, we emphasize the role of Koszul duality—a ubiquitous mathematical notion to which we provide a friendly introduction—in field theory and string theory. After illustrating the appearance of Koszul duality in the “toy” example of holomorphic Chern-Simons theory, we describe how (a deformation of) Koszul duality relates bulk and boundary operators in our twisted setup, and explain how one can compute algebra OPEs diagrammatically using this notion. Further details, results, and computations will appear in a companion paper.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

The LSU-Argonne conversion electron spectrometer: A new detector for the X-Array and SATURN decay station

In this study, a new conversion electron detector has been commissioned at the ATLAS/ CARIBU facility at Argonne National Laboratory. The LSU-Argonne Conversion Electron Spectrometer (LACES) is a LN 2 -cooled Si(Li) detector system designed to be incorporated into a decay station that comprises the dedicated HPGe clover array with a box geometry (X -Array) and the Scintillator and Tape Using Radioactive Nuclei (SATURN) device. This integration enables simultaneous measurements of conversion electrons and gamma-rays in decay experiments, yielding novel information on transition multipolarities, electric monopole transitions, and isomeric states that decay mostly via conversion electrons. A measurement of the energy resolution of LACES yielded 2.3-keV FWHM at 975 keV for electrons and 1.3-keV FWHM at 75 keV for X-rays. A detailed study of the absolute detection efficiency (at 5 mm from the source) was performed, where this quantity was determined experimentally in the range of electron transition energies between 25.5 keV and 1047.8 keV and subsequently simulated using the GEANT4 code. Measurement and simulations are found to be in excellent agreement. A precise characterization, for this type of detector system, of the absolute detection efficiency for such a wide energy range is reported for the first time.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Crystal structure prediction with host-guided inpainting generation and foundation potentials

Unconditional crystal structure generation with diffusion models faces challenges in identifying symmetric crystals as the unit cell size increases. Here, we present the crystal host-guided generation (CHGGen) framework to address this challenge through conditional generation using an inpainting method, which optimizes a fraction of atomic positions within a predefined and symmetrized host structure to improve the success rate for symmetric structure generation. By integrating inpainting structure generation with a foundation potential for structure optimization, we demonstrate the method on the ZnS–P 2 S 5 and Li–Si chemical systems, where the inpainting method generates a higher fraction of symmetric structures than unconditional generation. The practical significance of CHGGen extends to enabling the structural modification of crystal structures, particularly for systems with partial occupancy or intercalation chemistry. The inpainting method also allows for seamless integration with other generative models, providing a versatile framework for accelerating materials discovery.

Zhong, Peichen [University of California, Berkeley↗