| NSF Org: |
OIA OIA-Office of Integrative Activities |
| Recipient: |
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| Initial Amendment Date: | December 7, 2020 |
| Latest Amendment Date: | May 20, 2021 |
| Award Number: | 2033397 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Jose Colom
jcolom@nsf.gov (703)292-7088 OIA OIA-Office of Integrative Activities O/D Office Of The Director |
| Start Date: | December 15, 2020 |
| End Date: | November 30, 2024 (Estimated) |
| Total Intended Award Amount: | $252,491.00 |
| Total Awarded Amount to Date: | $252,491.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
2301 S 3RD ST LOUISVILLE KY US 40208-1838 (502)852-3788 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
2301 S 3rd Street Louisville KY US 40292-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | EPSCoR Research Infrastructure |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.083 |
ABSTRACT
Solid-state sodium (Na) superionic conductors play a significant role in applications for sensors and solid-state Na batteries. Chalcogenide Na-ion conductors have attracted intense attentions due to high Na+ ionic conductivity and cold-press included densification. For these conductors, the presence of Na defects (i.e. vacancies or interstitials) in their crystal structures strongly influence their ionic conductivities. Thus, it is essential to better understanding on the subtle structural change for the synthesis and doping of chalcogenide Na-ion conductors. One main challenge is the difficulty to accurately catch the subtle defect structure through regular X-ray diffraction technology. This project takes advantages of high resolution of neutrons to access advanced neutron facilities at Oak Ridge National Laboratory (ORNL), where the PI and her collaborators will investigate the crystal structures of Na3SbS4-xSex materials to obtain the fundamental knowledge of defect chemistry in chalcogenide conductors. The findings of this research will promote the development of new solid electrolytes for high performance solid-state Na batteries. In addition, this project will establish a longstanding collaboration between University of Louisville (UofL) and ORNL, which is a bridge to benefit other faculties at Kentucky to foster more collaborative research in boarder materials science fields.
Chalcogenide Na superionic conductors (i.e. Na3PCh4 and Na3SbCh4 (Ch=S, Se)) have great potential for applications in solid-state Na batteries. In these conductors, defect chemistry such as Na vacancies significantly affect the ion transport across crystal frameworks. The goal of this proposed research is to use Na3SbS4-xSex conductors as model materials to understand the physical principle underlying the defect changes and reveal how the defect local structures influence the Na+ ion diffusion. Through a collaborative research with neutron scientists in Spallation Neutron Source (SNS) at ORNL, we aim to advance the current state-of-the-art understanding on defect chemistry and their effects on the polymorphs as well as ion transport in chalcogenide Na-ion conductors. This research will involve: (1) Employ in situ neutron diffraction to closely observe phase formation and track the subtle structure changes such as Na defects for Na3SbS4-xSex conductors; (2) Reveal the Se doping effects on the crystal structure (phase stability and Na defect dynamics) as well as the ion diffusion across crystals of Na3SbS4-xSex conductors. The successful demonstration of the proposed work will provide a new fundamental understanding on the synthesis and ion transport in Na3SbS4-xSex chalcogenide conductors. The obtained knowledge will not only pave the way to understand other defects-contained crystalline Na-ion conductors, but also promote the development of new solid electrolytes in solid-state Na batteries for future energy storage.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Chalcogenide Na-ion conductors, as a representative family of solid-state ion conductors, have gained significant attention due to their impressive ionic conductivities. Ion transport in these conductors is strongly influenced by phase purity and structural defects. Among various strategies, doping chemistry has emerged as an effective approach to introduce structural disorder and enhance ionic transport. This project has research objectives to study (1) in-situ synthesis of chalcogenide Na-ion conductors by neutron diffraction; (2) the doping effects on structure and ion transport for chalcogenide conductors.
In this project, we have access and employed in-situ neutron diffraction to investigate the solid-state reaction of chalcogenide Na-ion conductors with/without doping, specifically, Na3SbS4 and selenium-doped Na3SbS3.5Se0.5. In-situ neutron experiment results reveal that this solid reaction happens fast at relatively low temperatures (below 350 °C) to form cubic structure for both conductors, then the crystalline structure transitions to a molten state when the temperature rises above 600 °C. Se-doping doesn’t significantly influences the solid-state reaction, in contrast, it results in the cubic-to-tetragonal phase transition temperature up on cooling. Specifically, the cubic phase can be stabilized to 110 °C for Na3SbS3.5Se0.5 other than 160 °C for Na3SbS4. In addition, we also have synthesized Na3SbS4-xSex conductors with varying amounts of Se doping (0≤x≤ 2.0) by controlling the S/Se ratio in the precursors. XRD results show Se doping not only expands the lattice parameters (due to the large ion radium of Se than S) but also leads to a phase transition from a tetragonal structure to a mixed phase (tetragonal and cubic), and eventually to a cubic structure. Nevertheless, among different Se doping contents, Na3SbS3Se exhibits the highest ionic conductivity, which is due to the synergies of Na+ vacancies and host dynamics that jointly enhancing ionic diffusivity.
Through this project, we could work closely with neutron scientists and other collaborators to use neutron scattering as a powerful tool to investigate solid-state ion conductors to deeply understand the correlations between structure, ion transport and diffusion. We submitted more than 10 user proposals to request access to neutron facilities (e.g., VULVAN, BASIS, NOMAD) at Oak ridge national laboratory (ORNL). The PI and graduate students have visited multiple times to ORNL to run experiments, learn data analysis and discuss results with neutron scientists at ORNL. Moreover, we also have attended several workshops and user conference that organized in national laboratory to learn more advanced characterization tools.
This project also offers the opportunity to train 2 graduate students at University of Louisville to learn advanced neutron knowledges and neutron scattering techniques as well as new software for data analysis. Moreover, they have the chance to conduct experiments at the neutron facilities and interact with senior neutron scientists. One PhD student has graduated (is currently as a postdoc researcher associate) and the other one is going to graduate soon. These experiments greatly benefit for their career development.
Last Modified: 03/31/2025
Modified by: Hui Wang
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