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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Quantifying the Reactivity of Isolated Li x Si Domains in Si Anodes Using Operando NMR

The use of Si anodes can greatly improve the energy density of Li-ion batteries. However, understanding and mitigation of calendar aging remains a barrier to commercialization. Here, in this short report, we utilize operando Nuclear Magnetic Resonance (NMR) spectroscopy to detect and quantify lithium silicides (Li x Si) as they form and react within Si anodes in pouch cells during calendar aging. We provide direct experimental evidence of complex aging phenomena in the Si anodes, including both SEI growth and dissolution during storage. Formation of electrochemically isolated Li x Si is also observed, as indicated by the partial persistence of highly lithiated phases after the cell is discharged. Remarkably, we show that these isolated domains can themselves self-discharge over time, suggesting that their detection can be challenging in post-mortem studies. Finally, we show that aging outcomes depend heavily on the type of silicon particles contained within the electrode, and that certain surface coatings can help decrease the reactivity between lithium silicides and the electrolyte.

Li-ion battery↗
DOE OSTI2020

Materials Data on LiSi by Materials Project

Si(Li) is Zintl Phase structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional and consists of two Si(Li) frameworks. Li is bonded to four equivalent Si atoms to form distorted corner-sharing LiSi4 tetrahedra. All Li–Si bond lengths are 2.69 Å. Si is bonded to four equivalent Li atoms to form distorted corner-sharing SiLi4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2ZnSi by Materials Project

Li2ZnSi crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form a mixture of distorted corner, edge, and face-sharing LiSi4 tetrahedra. There are one shorter (2.74 Å) and three longer (2.80 Å) Li–Si bond lengths. In the second Li1+ site, Li1+ is bonded to four Si4- atoms to form a mixture of distorted corner, edge, and face-sharing LiSi4 tetrahedra. There are one shorter (2.73 Å) and three longer (2.80 Å) Li–Si bond lengths. In the third Li1+ site, Li1+ is bonded to four Si4- atoms to form a mixture of distorted corner, edge, and face-sharing LiSi4 tetrahedra. There are one shorter (2.73 Å) and three longer (2.80 Å) Li–Si bond lengths. In the fourth Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form a mixture of distorted corner, edge, and face-sharing LiSi4 tetrahedra. There are one shorter (2.72 Å) and three longer (2.80 Å) Li–Si bond lengths. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Zn–Si bond lengths are 2.44 Å. In the second Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Zn–Si bond lengths are 2.44 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 11-coordinate geometry to eight Li1+ and three equivalent Zn2+ atoms. In the second Si4- site, Si4- is bonded in a 11-coordinate geometry to eight Li1+ and three equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2ZnSi by Materials Project

Li2ZnSi crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four Si4- atoms to form a mixture of distorted face, edge, and corner-sharing LiSi4 tetrahedra. There are one shorter (2.73 Å) and three longer (2.80 Å) Li–Si bond lengths. In the second Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form a mixture of distorted face, edge, and corner-sharing LiSi4 tetrahedra. There are one shorter (2.71 Å) and three longer (2.80 Å) Li–Si bond lengths. In the third Li1+ site, Li1+ is bonded to four Si4- atoms to form a mixture of distorted face, edge, and corner-sharing LiSi4 tetrahedra. There are one shorter (2.74 Å) and three longer (2.79 Å) Li–Si bond lengths. In the fourth Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form a mixture of distorted face, edge, and corner-sharing LiSi4 tetrahedra. There are one shorter (2.76 Å) and three longer (2.79 Å) Li–Si bond lengths. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Zn–Si bond lengths are 2.44 Å. In the second Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Zn–Si bond lengths are 2.44 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 11-coordinate geometry to eight Li1+ and three equivalent Zn2+ atoms. In the second Si4- site, Si4- is bonded in a 11-coordinate geometry to eight Li1+ and three equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li14MgSi4 by Materials Project

Li14MgSi4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent Si4- atoms. There are a spread of Li–Si bond distances ranging from 2.62–2.80 Å. In the second Li1+ site, Li1+ is bonded in a distorted trigonal planar geometry to three equivalent Si4- atoms. There are one shorter (2.63 Å) and two longer (2.76 Å) Li–Si bond lengths. In the third Li1+ site, Li1+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent Si4- atoms. There are a spread of Li–Si bond distances ranging from 2.61–2.81 Å. In the fourth Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form LiSi4 tetrahedra that share corners with four equivalent LiSi4 tetrahedra and corners with four equivalent MgSi4 tetrahedra. There are two shorter (2.88 Å) and two longer (2.90 Å) Li–Si bond lengths. Mg2+ is bonded to four equivalent Si4- atoms to form MgSi4 tetrahedra that share corners with eight equivalent LiSi4 tetrahedra. All Mg–Si bond lengths are 2.85 Å. Si4- is bonded to eleven Li1+ and one Mg2+ atom to form a mixture of distorted edge and face-sharing SiLi11Mg cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSi by Materials Project

Si(Li) crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Li is bonded in a 4-coordinate geometry to five equivalent Si atoms. There are a spread of Li–Si bond distances ranging from 2.63–2.89 Å. Si is bonded in a 9-coordinate geometry to five equivalent Li and three equivalent Si atoms. There are two shorter (2.42 Å) and one longer (2.50 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiSi by Materials Project

Si(Li) crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Li is bonded in a 8-coordinate geometry to five equivalent Si atoms. There are a spread of Li–Si bond distances ranging from 2.62–2.91 Å. Si is bonded in a 8-coordinate geometry to five equivalent Li and three equivalent Si atoms. There are one shorter (2.43 Å) and two longer (2.46 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2MgSi by Materials Project

Li2MgSi crystallizes in the cubic P-43m space group. The structure is three-dimensional. there are three inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four equivalent Li1+ and four equivalent Si4- atoms to form distorted LiLi4Si4 tetrahedra that share corners with sixteen MgSi4 tetrahedra and edges with six equivalent LiSi4 tetrahedra. All Li–Li bond lengths are 2.51 Å. All Li–Si bond lengths are 2.73 Å. In the second Li1+ site, Li1+ is bonded to four equivalent Si4- atoms to form LiSi4 tetrahedra that share corners with eight equivalent LiSi4 tetrahedra, corners with eight MgSi4 tetrahedra, edges with two equivalent LiLi4Si4 tetrahedra, and edges with four equivalent MgSi4 tetrahedra. All Li–Si bond lengths are 2.75 Å. In the third Li1+ site, Li1+ is bonded in a 4-coordinate geometry to one Li1+ and three equivalent Si4- atoms. All Li–Si bond lengths are 3.03 Å. There are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four equivalent Si4- atoms to form MgSi4 tetrahedra that share corners with sixteen LiLi4Si4 tetrahedra and edges with six equivalent MgSi4 tetrahedra. All Mg–Si bond lengths are 2.78 Å. In the second Mg2+ site, Mg2+ is bonded to four equivalent Si4- atoms to form MgSi4 tetrahedra that share corners with eight LiLi4Si4 tetrahedra, corners with eight equivalent MgSi4 tetrahedra, edges with two equivalent MgSi4 tetrahedra, and edges with four equivalent LiSi4 tetrahedra. All Mg–Si bond lengths are 2.77 Å. Si4- is bonded in a distorted body-centered cubic geometry to seven Li1+ and four Mg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2ZnSi by Materials Project

Li2ZnSi crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a trigonal planar geometry to three equivalent Si4- atoms. All Li–Si bond lengths are 2.50 Å. In the second Li1+ site, Li1+ is bonded in a 1-coordinate geometry to one Zn2+ and four equivalent Si4- atoms. The Li–Zn bond length is 2.50 Å. There are one shorter (2.61 Å) and three longer (2.86 Å) Li–Si bond lengths. Zn2+ is bonded in a 5-coordinate geometry to one Li1+ and four equivalent Si4- atoms. There are one shorter (2.54 Å) and three longer (2.72 Å) Zn–Si bond lengths. Si4- is bonded in a 11-coordinate geometry to seven Li1+ and four equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Evaluation of lithium alloy anode materials for Li-TiS2 cells

A study was performed to select candidate lithium alloy anode materials and establish selection criteria. Some of the selected alloy materials were evaluated for their electrochemical properties and performance. This paper describes the criteria for the selection of alloys and the findings of the studies. Li-Si and Li-Cd alloys have been found to be unstable in the EC+2-MeTHF-based electrolyte. The Li-Al alloy system was found to be promising among the alloy systems studied in view of its stability and reversibility. Unfortunately, the large volume changes of LiAl alloys during charge/discharge cycling cause considerable 'exfoliation' of its active mass. This paper also describes ways how to address this problem. The rate of disintegration of this anode would probably be surpressed by the presence of an inert solid solution or a uniform distribution of precipitates within the grains of the active mass. It was discovered that the addition of a small quantity of Mn may improve the mechanical properties of LiAl. In an attempt to reduce the Li-Al alloy vs. Li voltage, it was observed that LiAlPb(0.1)Cd(0.3) material can be cycled at 1.5 mA/sq cm without exfoliation of the active mass.

Huang, C.-K.↗
DOE OSTI2020

Materials Data on Li2MgSi by Materials Project

Li2MgSi crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight lithium molecules and one Li7(MgSi)4 framework. In the Li7(MgSi)4 framework, there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four Si4- atoms to form distorted LiSi4 tetrahedra that share corners with six equivalent MgSi4 tetrahedra, corners with ten equivalent LiSi4 tetrahedra, edges with three equivalent LiSi4 tetrahedra, and edges with three equivalent MgSi4 tetrahedra. There are three shorter (2.75 Å) and one longer (2.77 Å) Li–Si bond lengths. In the second Li1+ site, Li1+ is bonded in a distorted single-bond geometry to one Si4- atom. The Li–Si bond length is 2.78 Å. Mg2+ is bonded to four Si4- atoms to form MgSi4 tetrahedra that share corners with six equivalent LiSi4 tetrahedra, corners with ten equivalent MgSi4 tetrahedra, edges with three equivalent LiSi4 tetrahedra, and edges with three equivalent MgSi4 tetrahedra. There are three shorter (2.75 Å) and one longer (2.77 Å) Mg–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a body-centered cubic geometry to eight equivalent Mg2+ atoms. In the second Si4- site, Si4- is bonded in a body-centered cubic geometry to four equivalent Li1+ and four equivalent Mg2+ atoms. In the third Si4- site, Si4- is bonded in a 8-coordinate geometry to fourteen Li1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Synthesis of Antiperovskite Solid Electrolytes: Comparing Li 3 SI, Na 3 SI, and Ag 3 SI

Prior calculations have predicted that chalcohalide anti-perovskites may exhibit enhanced ionic mobility compared to oxyhalide anti-perovskites as solid-state electrolytes. Herein, the synthesis of Ag-, Li- and Na-based chalcohalide anti-perovskites is investigated using first-principle calculations and in situ synchrotron X-ray diffraction. These techniques demonstrate that the formation of Ag 3 SI is facilitated by the adoption of a common body centered cubic packing of S 2– and I – in the reactants and products at elevated temperatures, with additional stabilization achieved by the formation of a solid solution of the anions. Further, the absence of these two features appears to hinder the formation of the analogous Li and Na anti-perovskites.

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

A 32-channels readout ASIC for X-ray spectrometry and tracking in the GAPS experiment

Here this work describes the architecture and the experimental results from the characterization of a 32-channels mixed-signal Application-Specific Integrated Circuit (ASIC) developed for the readout of the lithium-drifted silicon, Si(Li), detectors of the General AntiParticle Spectrometer (GAPS) experiment dedicated to searching for dark matter. The instrument is designed for the identification of antiprotons, antideuterons and antihelium nuclei from cosmic rays during an Antarctic balloon mission scheduled for late 2024. A full custom integrated circuit, named SLIDER32 (32-channels Si-LI DEtector Readout) ASIC, has been produced in a commercial 180 nm CMOS technology. The ASIC is comprised of 32 low-noise analog readout channels featuring dynamic signal compression to comply with the wide input range, an 11-bit SAR ADC and a digital back-end section which is responsible for channel setting and for sending digital information to the data acquisition system (DAQ). The circuit design criteria and the experimental results are discussed in the paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Experimental results from the characterization of a 32-channels mixed-signal processor for the GAPS experiment

This work describes the experimental results obtained from the characterization of a 32-channels readout ASIC that is the core of a module composed by 4 Lithium-drifted Silicon, Si(Li), detectors. The module is the building block of a tracker in an upcoming balloon experiment. The activity is carried out within the General AntiParticle Spectrometer (GAPS) international collaboration, whose objective is the indirect detection of dark matter through the detection of antiparticles present in cosmic rays at low energies. The balloon flight is foreseen in 2024 from the McMurdo station in Antarctica. The ASIC is designed in a 180 nm CMOS technology and has 32 low-noise analog readout channels featuring a dynamic compression of the signal, an 11-bit SAR ADC, and a digital back-end section responsible for channel setting and for sending digital information to the data acquisition system of the tracker. This work has a twofold goal: it intends on the one hand to verify the performance of the circuit, on the other to select at least 300 good samples to be used for the assembly of the GAPS Si(Li) tracker.

Riceputi, Elisa↗
DOE OSTI2026

Long cycle and calendar life of Si-based Li-ion batteries enabled by localized high-concentration electrolytes and their surprising water tolerance

Silicon-based anodes promise an increase in energy density for Li-ion batteries, yet they suffer from a poor calendar life. Researchers have posited that fluorinated lithium salt forms reactive side products that destroy the solid electrolyte interphase (SEI), even without cycling. HF is one such reactive side product formed from trace water contamination in the electrolyte. Some electrolytes, such as localized high concentration electrolytes (LHCEs) may improve cell stability in highly reactive systems, such as Li metal and Si. In the present study, LHCEs containing 200-300 ppm of water retained up to 8% greater capacity (1200-1300 mAh/g Si) in calendar life tests over 200 days compared to dried electrolytes (< 20 ppm water). Calendar aging took place at 100% state of charge. Cells with 200-300 ppm water performed comparably to cells with 20 ppm water in cycle life tests (900-1000 mAh/g Si) . Even adding 1000 ppm water did not lead to rapid capacity fade in cells undergoing cycle life tests. Nano-FTIR spectroscopy revealed chemical and structural differences in the SEI for cells with 1000 ppm water compared to 200-300 ppm water. The SEI differences, including increased Li2O concentration, may have contributed to improved calendar life. This research reveals the capabilities of LHCEs to improve the calendar and cycle life of Si-based Li-ion batteries, despite the presence of a highly reactive contaminant.

25 ENERGY STORAGE↗
NASA NTRS1972

Radiation-induced extrinsic photoconductivity in Li-doped Si.

Investigation of the effects of lithium on radiation-produced complexes having long-time stability by examining the localized energy levels in the forbidden gap which give rise to extrinsic photoconductivity. The levels are found to disappear and in some cases shift with annealing in the 100-450 C temperature range. Due to the complexity of the system and the present lack of adequate theory, no complete analysis of the data obtained could be made.

Fenimore, E.↗
DOE OSTI2023

Electrochemical Formation of Li-M-(M')-Si Phases Using Multivalent Electrolyte Salt Additives

Lithium-rich silicides (Li 15 Si 4 ), formed during the electrochemical lithiation of silicon, show high reactivity with electrolyte components that contribute to capacity decay, formal lithium loss, and low coulombic efficiency. Recently, the reactivity of lithium silicides was found to be suppressed by substituting a multivalent cation (i.e. Mg, Ca) for lithium that results in the room temperature formation of a ternary Li-M-Si phase. In this study, we explored a range of multivalent electrolyte salt additives (M = Ni, Cu, La, Ce, Sr, Ba, and Ca-Mg mixed salt) in a lithium-ion cell configuration and identified a room temperature electrochemical route to the formation of new ternary and quaternary lithium silicides. Using this method, both nickel and copper salts were found to plate onto the silicon electrode surface upon lithiation. Further, based on refined synchrotron XRD data, multivalent cations with an ionic radius similar to Na (~1.03 Å) or smaller can be inserted electrochemically into a formally cation-deficient Li 15 Si 4 host lattice to form new ternary (or quartenary) phases. The electrochemical synthesis of a new quaternary Li-M-M’-Si phase represents a facile route to preparing and scaling materials isostructural to the Heusler phase and electron-precise Li 14 MgSi 4 phase that results in enhanced cycling and calendar life performance.

25 ENERGY STORAGE↗