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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Te4MoW3(SeS)2 by Materials Project

(WTe2)2WSe2MoS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction; one WSe2 sheet oriented in the (0, 0, 1) direction; and two WTe2 sheets oriented in the (0, 0, 1) direction. In the MoS2 sheet, Mo6+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.47 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent Mo6+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In the WSe2 sheet, W+3.33+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing WSe6 pentagonal pyramids. All W–Se bond lengths are 2.56 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent W+3.33+ atoms. In each WTe2 sheet, W+3.33+ is bonded to six Te2- atoms to form distorted edge-sharing WTe6 pentagonal pyramids. All W–Te bond lengths are 2.72 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent W+3.33+ atoms. In the second Te2- site, Te2- is bonded in a 12-coordinate geometry to three equivalent W+3.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdIn2(SeS)2 by Materials Project

CdIn2S2Se2 is Spinel-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to four equivalent S2- atoms to form CdS4 tetrahedra that share corners with twelve equivalent InSe3S3 octahedra. The corner-sharing octahedral tilt angles are 57°. All Cd–S bond lengths are 2.65 Å. In the second Cd2+ site, Cd2+ is bonded to four equivalent Se2- atoms to form CdSe4 tetrahedra that share corners with twelve equivalent InSe3S3 octahedra. The corner-sharing octahedral tilt angles are 59°. All Cd–Se bond lengths are 2.63 Å. In3+ is bonded to three equivalent Se2- and three equivalent S2- atoms to form InSe3S3 octahedra that share corners with six CdS4 tetrahedra and edges with six equivalent InSe3S3 octahedra. All In–Se bond lengths are 2.77 Å. All In–S bond lengths are 2.68 Å. Se2- is bonded to one Cd2+ and three equivalent In3+ atoms to form a mixture of distorted edge and corner-sharing SeCdIn3 trigonal pyramids. S2- is bonded in a distorted rectangular see-saw-like geometry to one Cd2+ and three equivalent In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoW(SeS)2 by Materials Project

MoSe2WS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of two MoSe2 sheets oriented in the (0, 0, 1) direction and two WS2 sheets oriented in the (0, 0, 1) direction. In each MoSe2 sheet, Mo6+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing MoSe6 pentagonal pyramids. There are three shorter (2.53 Å) and three longer (2.54 Å) Mo–Se bond lengths. Se2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In each WS2 sheet, W2+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnCu2Sn(SeS)2 by Materials Project

Cu2ZnSnS2Se2 is Clathrate-derived structured and crystallizes in the orthorhombic Fmm2 space group. The structure is three-dimensional. Cu1+ is bonded to two equivalent Se2- and two equivalent S2- atoms to form CuSe2S2 tetrahedra that share corners with four equivalent CuSe2S2 tetrahedra, corners with four equivalent ZnSe2S2 tetrahedra, and corners with four equivalent SnSe2S2 tetrahedra. Both Cu–Se bond lengths are 2.44 Å. Both Cu–S bond lengths are 2.30 Å. Zn2+ is bonded to two equivalent Se2- and two equivalent S2- atoms to form ZnSe2S2 tetrahedra that share corners with four equivalent SnSe2S2 tetrahedra and corners with eight equivalent CuSe2S2 tetrahedra. Both Zn–Se bond lengths are 2.48 Å. Both Zn–S bond lengths are 2.39 Å. Sn4+ is bonded to two equivalent Se2- and two equivalent S2- atoms to form SnSe2S2 tetrahedra that share corners with four equivalent ZnSe2S2 tetrahedra and corners with eight equivalent CuSe2S2 tetrahedra. Both Sn–Se bond lengths are 2.59 Å. Both Sn–S bond lengths are 2.50 Å. Se2- is bonded to two equivalent Cu1+, one Zn2+, and one Sn4+ atom to form SeZnCu2Sn tetrahedra that share corners with four equivalent SeZnCu2Sn tetrahedra and corners with eight equivalent SZnCu2Sn tetrahedra. S2- is bonded to two equivalent Cu1+, one Zn2+, and one Sn4+ atom to form SZnCu2Sn tetrahedra that share corners with four equivalent SZnCu2Sn tetrahedra and corners with eight equivalent SeZnCu2Sn tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2GaAg(SeS)2 by Materials Project

AgCd2GaS2Se2 is Clathrate-derived structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ag1+ is bonded to one Se2- and three S2- atoms to form AgSeS3 tetrahedra that share corners with two equivalent AgSeS3 tetrahedra, corners with four equivalent GaSeS3 tetrahedra, and corners with six CdSe3S tetrahedra. The Ag–Se bond length is 2.64 Å. There are two shorter (2.58 Å) and one longer (2.68 Å) Ag–S bond lengths. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three Se2- and one S2- atom to form CdSe3S tetrahedra that share corners with three equivalent AgSeS3 tetrahedra, corners with three equivalent GaSeS3 tetrahedra, and corners with six CdSe3S tetrahedra. There are two shorter (2.59 Å) and one longer (2.72 Å) Cd–Se bond lengths. The Cd–S bond length is 2.63 Å. In the second Cd2+ site, Cd2+ is bonded to three Se2- and one S2- atom to form CdSe3S tetrahedra that share corners with three equivalent AgSeS3 tetrahedra, corners with three equivalent GaSeS3 tetrahedra, and corners with six CdSe3S tetrahedra. There are one shorter (2.59 Å) and two longer (2.69 Å) Cd–Se bond lengths. The Cd–S bond length is 2.54 Å. Ga3+ is bonded to one Se2- and three S2- atoms to form GaSeS3 tetrahedra that share corners with two equivalent GaSeS3 tetrahedra, corners with four equivalent AgSeS3 tetrahedra, and corners with six CdSe3S tetrahedra. The Ga–Se bond length is 2.50 Å. There are one shorter (2.29 Å) and two longer (2.47 Å) Ga–S bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to one Ag1+ and three Cd2+ atoms to form SeCd3Ag tetrahedra that share corners with six SeCd3Ag tetrahedra and corners with six SCdGaAg2 tetrahedra. In the second Se2- site, Se2- is bonded to three Cd2+ and one Ga3+ atom to form SeCd3Ga tetrahedra that share corners with six SeCd3Ag tetrahedra and corners with six SCdGaAg2 tetrahedra. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Ag1+, one Cd2+, and one Ga3+ atom to form SCdGaAg2 tetrahedra that share corners with six SeCd3Ag tetrahedra and corners with six SCdGaAg2 tetrahedra. In the second S2- site, S2- is bonded to one Ag1+, one Cd2+, and two equivalent Ga3+ atoms to form SCdGa2Ag tetrahedra that share corners with six SeCd3Ag tetrahedra and corners with six SCdGaAg2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Te4Mo3W(SeS)2 by Materials Project

(MoTe2)2MoSe2WS2 is Molybdenite-derived structured and crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one MoSe2 sheet oriented in the (0, 0, 1) direction; two MoTe2 sheets oriented in the (0, 0, 1) direction; and one WS2 sheet oriented in the (0, 0, 1) direction. In the MoSe2 sheet, Mo+4.67+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing MoSe6 pentagonal pyramids. All Mo–Se bond lengths are 2.56 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Mo+4.67+ atoms. In each MoTe2 sheet, Mo+4.67+ is bonded to six Te2- atoms to form distorted edge-sharing MoTe6 pentagonal pyramids. All Mo–Te bond lengths are 2.71 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Mo+4.67+ atoms. In the second Te2- site, Te2- is bonded in a 12-coordinate geometry to three equivalent Mo+4.67+ atoms. In the WS2 sheet, W2+ is bonded to six S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.47 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted T-shaped geometry to three equivalent W2+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent W2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoW(SeS)2 by Materials Project

MoSe2WS2 is Molybdenite-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of two MoSe2 sheets oriented in the (0, 0, 1) direction and two WS2 sheets oriented in the (0, 0, 1) direction. In each MoSe2 sheet, Mo6+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing MoSe6 pentagonal pyramids. All Mo–Se bond lengths are 2.53 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Mo6+ atoms. In each WS2 sheet, W2+ is bonded to six equivalent S2- atoms to form distorted edge-sharing WS6 pentagonal pyramids. All W–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent W2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zr2(SeS)3 by Materials Project

ZrSSe2ZrSeS2 crystallizes in the monoclinic Pm space group. The structure is two-dimensional and consists of one ZrSeS2 ribbon oriented in the (0, 1, 0) direction and one ZrSSe2 sheet oriented in the (0, 0, 1) direction. In the ZrSeS2 ribbon, Zr3+ is bonded in a 6-coordinate geometry to two equivalent Se and four S2- atoms. Both Zr–Se bond lengths are 2.76 Å. There are two shorter (2.63 Å) and two longer (2.64 Å) Zr–S bond lengths. Se is bonded in a distorted L-shaped geometry to two equivalent Zr3+ atoms. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Zr3+ and one S2- atom. The S–S bond length is 2.08 Å. In the second S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Zr3+ and one S2- atom. In the ZrSSe2 sheet, Zr3+ is bonded in a 2-coordinate geometry to four Se and two equivalent S2- atoms. All Zr–Se bond lengths are 2.76 Å. Both Zr–S bond lengths are 2.63 Å. There are two inequivalent Se sites. In the first Se site, Se is bonded in a 4-coordinate geometry to two equivalent Zr3+ and two equivalent S2- atoms. There are one shorter (2.23 Å) and one longer (3.20 Å) Se–S bond lengths. In the second Se site, Se is bonded in a distorted L-shaped geometry to two equivalent Zr3+ atoms. S2- is bonded in a 2-coordinate geometry to two equivalent Zr3+ and two equivalent Se atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Natural colloids facilitated transport of steroidal estrogens in saturated porous media: Mechanism and processes

Steroid estrogens (SEs) are widely distributed in terrestrial environment, whilst the transport of SEs in groundwater is not well understood. Specifically, the effects of ubiquitous natural colloids on the SEs transport are unclear. Here, the influence of inorganic colloids (i.e. silica and illite) and organic colloids, i.e. Humic acid (HA), on the transport of estrone (E1) and estradiol (E2) in saturated porous media were studied in laboratory scale column experiments. Characterization on the colloids and the column packing material was conducted to provide bases for the interpretation of column test findings. Results showed that the transport of SEs was facilitated by the nature colloids that were migrating through the saturated porous media. About 38.5% of E1 and 24.6% of E2 were retained in the column when colloids were absent in the system. Further, when transporting with silica colloids, illite colloids, and HA colloids, the transport of E1 was enhanced by 15.64%, 11.17%, and 25.60%, respectively; whilst the transport of E2 was improved by 19.56%, 23.06%, and 36.40%, respectively. The colloids’ SEs transport enhancement depended not only on the mobility of the colloids but also on their geochemical characteristics. The tested organic colloids showed 1.5-2.5 times greater ability on promoting the transport of SEs than the inorganic ones. The proposed mechanisms of nature colloids facilitated transport of SEs include competing for adsorption sites on the sand surfaces by the colloids resulting mobilization of adsorbed SEs from solid matrix, and transport of colloids as carriers for SEs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Building Alternative Indices of Socioeconomic Status for Population Modeling in Data-Sparse Contexts (Short Paper)

Population modeling requires clear definitions of socioeconomic status (SES) to ensure overall estimate accuracy and locate potentially underserved subpopulations. This presents a challenge as SES can be measured in myriad ways and for divergent purposes, and the data required to calculate these metrics may be lacking, particularly in low and middle income countries (LMICs). To support more refined SES measurement, we explore improvements upon the Demographic and Health Survey’s (DHS) Wealth Index (DHS-WI) using alternative characterizations of SES based on multiple correspondence analysis (MCA) and hierarchical clustering. We produce the MCA-derived metrics first on a full suite of household economic, demographic, and dwelling variables, then on a reduced set of occupant-only SES characteristics. We explore the utility of these metrics relative to DHS-WI based on their ability to 1) differentiate DHS household types and 2) identify mixtures of SES levels within DHS samples and mapped at high spatial resolution. We find that our full suite MCA yields more clearly defined SES segments and that our reduced MCA delineates occupant SES most clearly, suggesting potential pathways to improve upon the DHS-WI in future population modeling efforts for LMICs.

Cunningham, Angela↗
DOE OSTI2021

Materials design of sodium chloride solid electrolytes Na3MCl6 for all-solid-state sodium-ion batteries

All-solid-state sodium-ion batteries have attracted increasing attention owing to the low cost of sodium and the enhanced safety compared to conventional Li-ion batteries. Recently, halides have been considered as promising solid electrolytes (SEs) due to their favorable combination of high ionic conductivity and chemical stability against high-voltage cathode materials. Although a wide variety of lithium chloride SEs, Li 3 MCl 6 , have been developed for high-voltage all-solid-state batteries, only a limited number of sodium chloride SEs have been reported. This study aims to offer a material design insight for the development of sodium chloride SEs through systematic assessment of the phase stability, electrochemical stability, and transport properties of novel Na 3 MCl 6 SEs. Structural calculations indicate that Na 3 MCl 6 exhibits trigonal $P\bar{3}$1c, monoclinic P2 1 /n, and trigonal $R\bar{3}$ phases, and the stable phase of Na 3 MCl 6 is dependent on the type and ionic radius of M. Na 3 MCl 6 typically exhibits a high oxidation potential, demonstrating good electrochemical stability against cathodes. The bond-valence site energy and ab initio molecular dynamics calculations revealed that Na 3 MCl 6 with P2 1 /n and $R\bar{3}$ phases showed low ionic conductivity, while the $P\bar{3}$1c phase slightly improved the ionic conductivity of Na 3 MCl 6 . The formation of Na vacancies by aliovalent substitution considerably increased the ionic conductivity up to four orders of magnitude for pristine Na 3 MCl 6 , exhibiting ~10 –5 S cm –1 for trigonal $P\bar{3}$1c and $R\bar{3}$ phases. The formation of defects could further enhance the ionic conductivity of Na 3 MCl 6 , and the optimization of defect type and ratio can be helpful in developing superionic Na chloride SEs. The material design of Na 3 MCl 6 in this study will provide fundamental guidelines for the development of novel sodium halide SEs for all-solid-state sodium-ion batteries.

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

Structural evolution during solution-based synthesis of Li 7 P 3 S 11 solid electrolyte by synchrotron X-ray total scattering

Solution-based synthesis has emerged as a promising approach for scalable and efficient synthesis of solid electrolytes (SEs). However, the ionic conductivity of solution-synthesized SEs is much lower than that of SEs synthesized by solid state approaches. The structural evolution during the synthesis of SEs is crucial to explaining the decreased ionic conductivities but has not been well understood. Here, in this work, we use synchrotron X-ray total scattering combined with pair distribution function (PDF) analysis to understand the structural evolution during annealing of the solution-processed precursor for the synthesis of Li 7 P 3 S 11 SEs. Combining Bragg diffraction and diffuse scattering, X-ray total scattering enables detection of structural information including phase transition and crystallinity. The results show that the formation of Li 7 P 3 S 11 glass-ceramic starts at 230 °C. Increasing the annealing temperature helps to improve the crystallinity, but the degree of crystallization is still lower than 70.3% even after annealing at 290 °C when thermal decomposition of Li 7 P 3 S 11 to Li 4 P 2 S 6 has occurred. PDF analysis also revealed the existence of acetonitrile used in the solution-based synthesis in the SEs after annealing at high temperatures. The results rationalize the synthesis–property relationship, explain why annealing at 290 °C provides the highest ionic conductivity at the studied temperatures due to an optimal balance for achieving a high crystallinity while suppressing severe decomposition of Li 7 P 3 S 11 , and provide novel insights to develop approaches for synthesizing superior Li 7 P 3 S 11 SEs on a large scale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Energy-Storing Cryogenic Carbon Capture™ for Utility and Industrial-scale Processes (Final Report)

This project leverages work completed under funding from previous U.S. Department of Energy (DOE) projects and other sources of funding around the Cryogenic Carbon Capture Process™ (CCC). The purpose of this project is to further develop a perturbation of the CCC process that stores energy called the Cryogenic Carbon Capture™ Energy Storing (CCC-ES) process. The successful completion of the tasks in this project has prepared the CCC-ES process for scaling and developed initial plans and a feasibility analysis for an engineering-scale or small-commercial scale system that can store at least 10 MWh of energy. The specific areas of work in this project are: (1) Develop a conceptual, site-specific integrated process flow diagram: Sustainable Energy Solutions (SES) developed a conceptual, site-specific plan including a process flow diagram for integrating CCC-ES at a specific location. The proposed system was based on a typical engineering-scale CCC system designed to capture 30-50 metric tonnes of CO 2 per day (TPD), with modifications and additional changes and equipment put in place to add the energy storage element to the system. The 30-50 TPD scale corresponds to the required 10 MWh of stored energy. This task includes updating simulation software for transient analysis. SES also coordinated with the Jim Bridger Power Plant in Point of Rocks, Wyoming to get site-specific data. Using these data, SES completed site-specific preliminary process flow diagrams, estimated capital and operating costs for the CCC-ES system, and used the upgraded software package to estimate the primary figures of merit. (2) Complete a technoeconomic analysis (TEA): SES completed a full-scale TEA of the CCC-ES system to meet specific success criteria. This TEA used process information from the host site selected above. (3) Technology and data gap assessment for the CCC-ES process: As part of the technology gap assessment, SES performed an assessment of the best alternative energy storage solutions including figures of merit and operational strengths and weaknesses. SES then compared the proposed system with a discussion of how it addresses the weaknesses of alternative systems, showing for example a cost of stored energy at less than $50/MWh and with a roundtrip efficiency of greater than 95%. This assessment includes technical and other risk analyses and technology gaps with research and development needs to commercialize the process by 2030. Finally, work includes a commercialization roadmap/development pathway outlining the major milestones to move to a commercially operating CCC-ES system. (4) Phase II pre-FEED project plan: SES completed a project plan for the Phase II pre-FEED analysis using the same host site as in the Phase I conceptual study.

03 NATURAL GAS↗
DOE OSTI2024

The Key Role of Grain Boundary Dynamics in Revolutionizing the Potential of Solid Electrolytes

Solid electrolytes (SEs) have the potential to enhance the safety and performance of Li-metal batteries. However, the existence of grain boundaries in polycrystalline SEs presents a significant challenge for both ionic and electronic migration, promoting the propagation of detrimental lithium dendrites. This study compares the roles of grain boundaries in electrical properties of three distinct SEs including garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZO), argyrodite-type Li 6 PS 5 Cl (LPSC), and NASICON-type Li 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 (LATP). Results demonstrate that the electronic and ionic conductivities of solid-state electrolytes are affected differently by grain boundaries, depending on the specific type of electrolyte. For instance, LLZO and LATP experience dielectric breakdown at 3.7 and 5.3 V, respectively, while LPSC does not exhibit such behavior. Here, a new chemical modification is proposed that simultaneously alters the composition of both the surface and grain boundaries of SEs, ultimately reducing electronic conductivity for the LLZO SEs. Consequently, the proposed LLZO exhibits unprecedented dendrite-free cycling stability, achieving a remarkable 12 000-h lifetime at room temperature, surpassing conventional strategies such as surface coatings in dendrite mitigation. This study highlights the significance of modifying grain boundaries to design safe and durable Li-metal batteries. It provides new insights for developing SEs that are highly resistant to dendrite formation.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Unveiling the Mechanical and Electrochemical Evolution of Nanosilicon Composite Anodes in Sulfide-Based All-Solid-State Batteries

The utilization of silicon anodes in all-solid-state lithium batteries provides good prospects for facilitating high energy density. However, the compatibility of sulfide solid-state electrolytes (SEs) with Si and carbon is often questioned due to potential decomposition. Here, in this paper, operando X-ray absorption near-edge structure (XANES) spectroscopy, ex situ scanning electron microscopy (SEM), and ex situ X-ray nanotomography (XnT) are utilized to investigate the chemistry and structure evolution of nano-Si composite anodes. Results from XANES demonstrate a partial decomposition of SEs during the first lithiation stage, which is intensified by the presence of carbon. Nevertheless, the performances of first three cycles in Si–SE–C are stable, which proves that the generated media is ionically conductive. XnT and SEM results show that the addition of SEs and carbon improves the structural stability of the anode, with fewer pores and voids. A chemo-elasto-plastic model reveals that SEs and carbon buffer the volume expansion of Si, thus enhancing mechanical stability. The balance between the pros and cons of SEs and carbon in enhancing reaction kinetics and structural stability enables the Si composite anode to demonstrate the highest Si utilization with higher specific capacities and a better rate than pure Si and Si composite anodes with only SEs.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Polymerizations of 2-(Trimethylsilyl)ethanesulfonyl-activated aziridines

A novel N-sulfonyl aziridine, N-((2-(trimethylsilyl)ethyl)sulfonyl)-2-methyl-aziridine (SES-MeAz) was synthesized, and its controlled anionic ring-opening polymerization to form poly(SES-MeAz) studied. The desulfonylation of poly(SES-MeAz)s can be achieved under mild conditions, with tetrabutylammonium fluoride (TBAF) to form polypropylene imine (PPI), although purification of the PPI was not completely successful. The block copolymer p(pTs-MeAz)-b-p(SES-MeAz), (pTs-MeAz = N-para-tosyl-2-methyl-aziridine) was prepared by a sequential polymerization. The desulfonylation of the block copolymer is the first example of the selective removal of a sulfonyl protecting group from a poly(sulfonylazirdine) block copolymer and this is the first formation of a polysufonylaziridine-block-polypropylene imine copolymer. Three-armed star-shaped poly(SES-MeAz)s were also successfully synthesized and exhibited improved solubility compared with linear poly(SES-MeAz)s.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

A New General Paradigm for Understanding and Preventing Li Metal Penetration through Solid Electrolytes

The use of lithium (Li) or sodium (Na) metal anodes together with highly ion-conductive solid electrolytes (SEs) could provide batteries with a step improvement in volumetric and gravimetric energy densities. Unfortunately, these SEs face significant technical challenges, in large part because Li and Na dendrites can penetrate through SEs, leading to short circuits. The ability of such a soft material (Li or Na metal) to penetrate through ceramic is surprising from the point of view of models widely used in the Li-battery field. We introduce a concept, new to the battery field, for preventing penetration of lithium dendrites through SEs by putting the SE surfaces into a state of residual compressive stress. For a sufficiently high compressive stress, cracks have difficulty forming, and cracks that do form are forced to close, inhibiting dendrite penetration. This approach is widely used to solve commercially important stress corrosion cracking problems in metals and static fatigue problems in ceramics and glasses (e.g., Gorilla Glass). However, the technique will not be useful for SEs if the Li-ion transport rate through a SE is substantially reduced when the SE is under compression. Our molecular dynamics calculations for Li-ion transport through a common SE demonstrate that the introduction of even very high residual compressive stresses (~10 GPa) has only a modest effect on Li-ion transport kinetics, suggesting that this approach is viable and capable of providing a new paradigm for developing high-performance and mechanically stable SEs.

25 ENERGY STORAGE↗