| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | March 2, 2018 |
| Latest Amendment Date: | March 2, 2018 |
| Award Number: | 1751693 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Y. Kevin Chou
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | March 15, 2018 |
| End Date: | February 28, 2023 (Estimated) |
| Total Intended Award Amount: | $500,000.00 |
| Total Awarded Amount to Date: | $500,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
926 DALNEY ST NW ATLANTA GA US 30318-6395 (404)894-4819 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
225 North Avenue Atlanta GA US 30332-0002 |
| 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): |
CAREER: FACULTY EARLY CAR DEV, NANOMANUFACTURING |
| 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): | 47.041 |
ABSTRACT
Two-dimensional atomic layer materials have the potential to revolutionize energy storage devices, including rechargeable batteries, by improving energy and power performances. Currently, available manufacturing processes for two-dimensional materials require high temperatures or complex chemical treatment, which limits their large-scale production. This Faculty Early Career Development Program (CAREER) award investigates scalable electrochemical exfoliation and functionalization of two-dimensional materials with the aim of controlling their structures and properties for high-performance energy storage devices. Two-dimensional materials come in many compositions and are increasingly utilized in consumer electronics, electric vehicles, smart grids, and renewable energy systems. The capability to produce high quality two-dimensional materials contributes significantly to the nation's economy and advances prosperity and welfare. The award aligns well with NSF's Quantum Leap effort because two-dimensional materials with controlled film thickness and point defects are candidate materials for quantum devices, including sensing, computing and communicating. This research is multidisciplinary, including manufacturing, electrochemistry and nanotechnology, and motivates students with diverse backgrounds to consider future careers in science and engineering. The project develops an energy education module in collaboration with high school teachers to teach energy storage mechanisms and calculation of energy and power densities tied with chemistry, physics, and math curricula. The energy education module can be tested and expanded over a broad range of underrepresented students through NSF INCLUDES program.
The electrochemical manufacturing process has many advantages over conventional manufacturing techniques of fabricating two-dimensional (2D) atomic layer materials, including low-cost, simple operation, rapid production rate, and in-situ functionalization, by taking advantage of scalable and controllable nature of the electrochemical process. However, some scientific barriers, such as mechanistic understanding of electrochemical exfoliation and quantitative methods for controlling the structure and properties, need to be overcome in order to realize the full potential of electrochemical manufacturing of 2D materials. This project investigates comprehensive and general expansion, exfoliation and functionalization mechanisms during the manufacture of these materials in electrochemical processing, specifically, structural changes and gas formation as a function of applied potential. It evaluates properties of the electrochemical processed materials, and establishes processing parameter-structure-property relationships. The work can potentially transform the manufacturing process of 2D materials into a highly scalable and controllable process that can fabricate structure- and property-tuned 2D nanomaterials for specific target applications.
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.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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.
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.
The electrochemical exfoliation process, which converts graphite into graphene, has gained attention due to its cost-effectiveness, simplicity, solution-based methodology, operation at low temperatures, and high production rate. This approach also shows promise for other two-dimensional (2D) materials. However, a comprehensive understanding of the electrochemical exfoliation mechanism is still needed, as it involves complex reactions such as ion intercalation, chemical oxidation, gas evolution, and mechanical expansion and exfoliation.
The goals of research carried out under NSF Award 1751693 were to understand the electrochemical expansion, exfoliation, and utilization of 2D layered materials at the nanoscale, and to use this understanding to control structures and corresponding properties of the processed materials that are tuned for energy storage device applications. The educational goal of this project is to introduce interdisciplinary nano and energy science/engineering to students with diverse backgrounds to motivate them to consider future careers in science and engineering.
Through the support of this NSF award, our team has conducted extensive research on the electrochemical exfoliation system for graphene. We have explored its operation both anodically and cathodically and proposed two straightforward strategies to enhance its function as a protective layer for lithium metal anodes in Lithium Metal Batteries (LMBs). Throughout our study, we have experimentally and computationally tested previously reported hypotheses.
Initially, our research focused on the anodic exfoliation of graphene in diluted aqueous acid electrolytes to confirm the hypothesis of superior exfoliation efficiency with sulfate-containing electrolytes. The successful transition from graphite to graphene primarily relies on the effective interaction of anions followed by water oxidation. In-situ gas analysis of the electrochemical exfoliation process revealed that oxygen is the primary gaseous product in sulfuric acid, highlighting its crucial role in exfoliating graphite. Efficient delivery of water molecules into the graphite structure is essential for successful exfoliation. Our study discovered that sulfate anions exhibit reversible intercalation/deintercalation behavior, facilitating their diffusion into the graphite structure and achieving the highest binding energy with the graphene layer, making them effective carriers of water molecules.
We have also significantly improved the less efficient cathodic exfoliation system by employing binary solvents as electrolytes. Recognizing the vital role of intercalation during exfoliation, we used dimethyl carbonate (DMC) as an intercalating agent to enhance the intercalation of Li cations into graphite interlayers. This improved intercalation was supported by the decrease in the solvation number of the co-intercalating dimethyl sulfoxide (DMSO) solvent surrounding the Li ion, as validated by Raman spectrum data with different volume ratios between DMSO and DMC solvents. The primary gaseous species contributing to exfoliation in the DMSO and DMC binary solvent system was methane, originating from electrolyte decomposition. In this process, the graphite foil acted as an electrocatalyst for the methane evolution reaction, resulting in a significant number of defects after exfoliation.
In terms of energy storage systems, we specifically demonstrated the application of electrochemically exfoliated graphene in Lithium Metal Batteries (LMBs), which are considered the next generation of lithium batteries. Graphene has proven to be highly effective as a protective layer on the lithium metal anode, ensuring stable lithium plating and stripping during battery cycling. However, the challenges associated with manipulating graphene have limited precise scientific research and large-scale production for various applications. To address these challenges, we have utilized the benefits of the electrochemical exfoliation system, which allows precise control over the properties of exfoliated graphene and scalability, while also introducing an artificial inorganic solid electrolyte interphase (SEI) by altering exfoliation parameters. Overall, our study demonstrated increased battery performance by employing exfoliated graphene-coated separators as efficient protective layers on lithium metal in LMBs.
This work has yielded several outcomes, including 1 completed Ph.D. thesis, 3 publications in peer-reviewed journals, and 2 manuscripts currently in preparation. Additionally, the research findings were presented at 6 conferences, showcasing the work to a wider audience. Moreover, this award has played a crucial role in supporting the education and training of students. Specifically, it has supported the education of 1 Ph.D. student, 5 undergraduate students, and 1 high school teacher. The PI and the high school teacher have collaborated to develop education modules that effectively integrate modern energy storage systems into K-12 curriculum, aligning them with high-school math, physics, and chemistry courses.
Last Modified: 06/28/2023
Modified by: Seung Woo Lee
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