Award Date
12-1-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Mechanical Engineering
First Committee Member
Kwang J. Kim
Second Committee Member
Jaeyun Moon
Third Committee Member
Brendan O'Toole
Fourth Committee Member
Woosoon Yim
Fifth Committee Member
Marykay Orgill
Number of Pages
306
Abstract
The increasing demand for greater energy storage capacity alongside the need to minimize the size of various devices, such as hybrid electric vehicles, medical devices, and pulsed power systems—has highlighted the necessity for advanced polymer film capacitors with high energy density. While traditional batteries and electronic devices have generally sufficed for many applications, their inherent size limitations hinder their ability to deliver the high levels of peak power required for certain demanding applications. This shortfall highlights the critical ongoing challenge within the energy storage sector to improve technology and more effectively meet these growing power requirements. Flexible Ionic Polymer Metal Composites (IPMCs) fabricated utilizing platinum (Pt) or gold (Au) are studied for their applicability as Solid Polymer Electrolyte (SPE) membranes for high--power capacitors, as they have demonstrated improved electrical and mechanical properties as electronic devices.
IPMCs are types of Electroactive Polymers (EAPs) that display large deflections in response to small electric fields or voltages. IPMCs are characterized by significant displacements, but low-density forces. Also, until recently, research on IPMC materials primarily focused on their potential as actuators. However, one of the most intriguing applications of IPMC now being explored is its use in energy storage capacitors. Furthermore, the exceptional properties of IPMC- for instance, soft, high flexibility, low weight, and the potential to reach high energy density- make it an ideal candidate to replace conventional capacitors or energy storage devices. In this research, sandwich structured IPMCs were designed and fabricated. The samples for this study were fabricated utilizing the chemical reduction process (impregnation-reduction or chemical deposition) because of good surface strength achieved using this method. The mechanism behind an IPMC’s energy storage abilities rests in its capability to store charges on its surface through the mobilities of ions. When an electric potential is applied to the material, the ions inside the polymer matrix travel towards one electrode of the IPMC, resulting in charge accumulation on the surface. IPMC can be charged and discharged quickly with little to no degradation in performance.
This dissertation targeted to improve the fundamental understanding of recently observed phenomena in flexible energy storage devices. It explored the influence of key fabrication parameters, temperature variations, and different solutions on the performance of the IPMC capacitors. The electrochemical performance of IPMC capacitors was thoroughly investigated under various mechanical loadings, particularly tension and bending, to understand their behavior and characteristics.
One primary objective of this study was to assess the impact of defects or cracks induced by tensile loading on both the mechanical properties and electrochemical behavior of the IPMC-based capacitors. During tensile testing, the deformation experienced by the IPMC strips led to alterations in the ion distribution and concentration within the polymer matrix, thereby influencing the material’s performance. Electrochemical Impedance Spectroscopy (EIS) was employed to measure these changes at room temperature across a frequency range of 10 KHz to 1 Hz, offering a straightforward and efficient method with consistent results. It was observed that the capacitance of the IPMC capacitor increased notably after significant cracking occurred in the platinum electrodes because of high tensile mechanical loads. Additionally, at lower frequencies (<100 >Hz), both the real (ε') and imaginary (ε") parts of permittivity exhibited an increase with the addition of loads, indicating a notable impact on the dielectric properties of the material. However, it was noted that at frequencies above 100 Hz, the permittivity showed weak dependence on the applied loads. Another aspect of the investigation involved analyzing the functionality of the capacitor under a wide spectrum of bending angles, ranging from 0 C to 100 C.
Through this work, this research underscored the IPMC capacitor’s adaptability to flexibly to diverse bending angles, making it particularly suitable for applications where traditional rigid capacitors may prove impractical or inefficient. Furthermore, the study contributed to the body of knowledge by employing advanced testing methods to evaluate the mechanical and electrochemical performance of this flexible capacitor under various conditions. The experimental findings were corroborated and further investigated using the COMSOL Multiphysics model to explore the characteristics of the surface electrodes.
Controlled Subject
Energy storage; Conducting polymers; Electrochemistry
Disciplines
Mechanical Engineering
File Format
File Size
7600 KB
Degree Grantor
University of Nevada, Las Vegas
Language
English
Repository Citation
Napollion, Liya S., "Investigation Ionic Polymer Metal Composite Capacitors through Fabrication, Experimentation, and Modeling" (2024). UNLV Theses, Dissertations, Professional Papers, and Capstones. 5196.
http://dx.doi.org/10.34917/38330408
Rights
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