[CCoE Notice] Cullen College Dissertation Defense Announcement- Mina Shanbedi

[Hutchinson, Inez A]

[Dissertation Defense Announcement at the Cullen College of Engineering]

Fundamental Understanding of Triboelectric Nanogenerators,

Carbon-Based Nanocomposites for Flexible Triboelectric Nanogenerators

and Modified Hydrogel Polymer Supercapacitors

for Energy Conversion and Storage purposes

Mina Shanbedi

December 5, 2023; 11:30 AM - 1:00 PM (CST)
Location: S234 Eng Bld 1

Teams: https://urldefense.com/v3/__https://teams.microsoft.com/l/meetup-join/19*3ameeting_ODYxZTNiOTItNDVkZC00ZDcxLTk3NGYtZTI5OTQzM2Y1NTQ4*40thread.v2/0?context=*7b*22Tid*22*3a*22170bbabd-a2f0-4c90-ad4b-0e8f0f0c4259*22*2c*22Oid*22*3a*22ec777e9f-8e31-4819-aec9-15489620cf17*22*7d__;JSUlJSUlJSUlJSUlJSUl!!LkSTlj0I!DqYBrUyl6IqRgzo048qyieGw4g8whpqb_g5V32BSLECCIHQCp4Prd1KLSah782hU3gkGmGQoHqAucLiSZRrkdtd8foQ$ 


Committee Chair:

Alamgir Karim, Ph.D.

Committee Members:

Haleh Ardebili, Ph.D. | Devin Shaffer, Ph.D. | Hadi Ghasemi, Ph.D. | Mim Rahimi, Ph.D.

Abstract

conventional techniques to harvest and store energy are challenged by the ever-increasing demand for versatile forms of electrical energy caused by the rapid expansion of the Internet of Things (IoTs). As emergent solutions, flexible triboelectric nanogenerators (TENGs) and gel polymer electrolyte supercapacitors (GPE SCs) have been invented and extensively studied in recent decades. Different TENGs are fabricated to scavenge mechanical energy from most natural sources and human motions, making them on-demand portable solutions to energy generation. On the other hand, rechargeable GPE SCs have played critical roles in energy evolution, owing to their ability to provide a rapid power supply and high power for portable and smart electronics and make a fossil fuel-free world possible.

At the beginning of this dissertation, a comprehensive review has been done on the fundamental mechanism and all available methods of TENG modification. TENG science is a young field, and many questions about the charge transfer mechanism and influential factors have not yet been answered. Many state-of-the-art methods are being suggested daily to enhance TENG performance towards a commercially available system. Chapter One covers all these new methods by categorizing them as physical-structural modifications and chemical modifications. They are poised to further the reach of TENG applications and make a positive impact on common issues related to TENG technology.

The second section is to present a robust route to fabricate flexible TENGs with multifunctionality by nano-patterning Polydimethyl Siloxane (PDMS) films. The carbon-based nanofillers were applied to increase the polymer’s capacitance, and the effect of nanofillers and their physical orientation were studied on the dielectric properties of the film and their effect on the final voltage and current output of the TENG. Also, the topography of TENGs' dielectric surface could promote higher power generation. The effect of patterning on output power is also studied to enable peak performance of the TENG.

Chapter 3 covered gel polymer electrolytes for supercapacitors. Gel polymer electrolytes are emerging as highly promising candidates due to their superior ionic conductivity compared to solid electrolytes, while avoiding the safety concerns associated with liquid electrolytes. This chapter provides a background about the utilization of PVA-based gel polymer electrolytes for flexible supercapacitors, highlighting key factors related to enhancements in ionic conductivity, mechanical characteristics, and overall electrochemical performance. Various ongoing research endeavors are discussed, aiming to address existing challenges and ultimately improve the ionic conductivity and electrochemical properties of these electrolytes.

The last part of this work presents the fabrication and characterization of all-solid-state supercapacitors based on gel polymer electrolytes. Efforts were made to increase the ion transfer and capacitance of the electrolyte and reduce the self-discharge. Halloysite nanotubes (HNTs) have been used as an effective electrolyte additive for the first time and were aligned in the Z direction with the assistance of a high-voltage electric field, which helps building direct paths for the ions to transfer through channels with ultra-high ionic conductivity because they are filled with ionic liquid (IL). Comprehensive electrochemical properties, along with the thermal properties of these SCs will be closely scrutinized in this work. As a further step towards enhancing the storage performance of the GPE supercapacitors, another less studied nanofiller, hexagonal boron nitride, was introduced to the current work and magnified the energy storage and capacitance of the system. The incorporation of h-BN nanosheets into the PVA-H2SO4 gel polymer, serving as both electrolyte and separator, results in a quasi-solid-state supercapacitor exhibiting notable characteristics, including elevated specific capacitance, commendable rate capability, and exceptional cycle stability. Operating at a current density of 0.5 A g-1, the quasi-solid-state supercapacitor achieves an electrode-specific capacitance of 133.5 F g-1, retaining an impressive 96.78% capacitance even after undergoing 2000 charge-discharge cycles. This h-BN nanosheets-doped Gel Polymer Electrolyte (GPE), marked by its excellent performance and straightforward synthesis methodology, emerges as a promising contender for high-performance quasi-solid-state supercapacitors and various electrochemical devices encompassing rechargeable batteries and fuel cells. Furthermore, this study illuminates the potential use of 2D materials in advanced Gel Polymer Electrolytes (GPEs).

[Engineered For What's Next]


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