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Mechanical Engineering MS Thesis Defense by Mr. Justice Iroegbu

When: Friday, May 13, 2022
9:00 AM - 11:00 AM
Where: > See description for location
Description: Mechanical Engineering MS Thesis Defense by Mr. Justice Iroegbu

DATE:
May 13, 2022

TIME:
9:00 a.m. - 11:00 a.m.

ZOOM LOCATION:
https://umassd.zoom.us/j/97680493591

Meeting ID: 976 8049 3591
Passcode: 500


TOPIC:
Molecular Dynamics Simulation of the Electrode-Electrolyte Interface in Electric Double Layer Supercapacitors

ABSTRACT:
Electric double-layer supercapacitors (EDLCs) are electrochemical energy storage devices that play a major role in today's energy landscape. Compared with the mainstream lithium batteries, EDLCs offer faster charge/discharge rates and improved safety because of their energy storage mechanism. Moreover, EDLCs using solid polymer electrolytes offer the possibility to develop multifunctional structural energy storage devices. However, it has been experimentally observed that the performance dramatically decreases when we switch liquid electrolytes to solid polymer ones in EDLCs. The fundamental mechanism behind this phenomenon is difficult to characterize experimentally. In this work, we study the electrode-electrolyte interface in EDLCs using molecular dynamics (MD) simulations, which can reveal atomic behaviors that are not experimentally measurable. We construct two models with graphene electrodes and different electrolytes, including an aqueous solution-based liquid electrolyte and a polymer-based solid electrolyte. Both systems are configured to contain the same salt concentration. The modeled systems are simulated via the LAMMPS package using the NPT-NVT (equilibration and production respectively) ensemble. Molecular phenomena such as the trajectories of atoms, Inner and Outer Helmholtz Layers (IHL and OHL), ion distributions, and electrode-ion screening effect are characterized at various applied charge levels. The results show that the polymer electrolyte system exhibits an IHL similar to the one in liquid electrolyte system that has been studied in literature. It is also observed that the concentration of ions at the electrode-electrolyte interface is lower for the polymer electrolyte than for the aqueous electrolyte. In addition, the ion-electrode distance in the polymer electrolyte is greater compared to that in the aqueous one. Ionic conductivities of the two systems are determined by both experimental measurements and simulations to validate the feasibility of MD simulations. These observations give us new molecular insights to the interface of polymer electrolyte-based EDLCs.

ADVISOR:
Dr. Caiwei Shen, Assistant Professor of Mechanical Engineering, UMass Dartmouth

COMMITTEE MEMBERS:
-Dr. Jun Li, Assistant Professor of Mechanical Engineering, UMass Dartmouth
-Dr. Maricris Mayes, Associate Professor of Chemistry and Biochemistry, UMass Dartmouth

Open to the public. All MNE students are encouraged to attend.

For more information, please contact Dr. Caiwei Shen (cshen2@umassd.edu, 508-999-8449).
Topical Areas: Faculty, General Public, Staff and Administrators, Students, Students, Graduate, Students, Undergraduate, University Community, College of Engineering, Mechanical Engineering, Lectures and Seminars, STEM Education, STEM