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Authors

Di ZhangFollow

ORCID

https://orcid.org/0000-0001-8155-6809

Access Type

Open Access Thesis

Document Type

thesis

Embargo Period

7-16-2020

Degree Program

Mechanical Engineering

Degree Type

Master of Science in Mechanical Engineering (M.S.M.E.)

Year Degree Awarded

2020

Month Degree Awarded

September

Abstract

In electrode double layer capacitor (EDLC), electrodes usually contain binder materials to provide adhesion between electrode materials. However, binder materials usually bring unwanted resistances to the component due to their non-conductivity properties and the occupation of ion cavities. The purpose of this thesis is to demonstrate the feasibility of fabricating electrodes for EDLCs by using carbon nanotubes (CNTs) and graphene oxide (GO) without using any binding materials. At the same time, investigating the binder-free electrode’s electrochemical properties and make an assumption of its potential application in the future.

The slurry of binder-free electrodes was fabricated by ultrasonicating water suspended CNTs and GO aqueous solution. The ultrasonicated mixture was then casted on an aluminum foil, followed by drying processes to form into an electrode film. By combining the CNTs/GO binder-free electrodes with aqueous electrolyte, a symmetrical electrode double layer capacitor (EDLC) was fabricated. The EDLC was also tested for electrochemical performance using a polyvinyl alcohol (PVA) based gel electrolyte. It was found that an electrode with a low resistance was achieved by eliminating the use of binders. The as-prepared sample had an equivalent series resistance (ESR) of 0.07 Ohms. Furthermore, a solid-state, binder-free EDLC sample achieved a specific capacitance of 0.2876 F/m2 in volumetric terms, or 58.24 mF/g in gravimetric terms.

The laboratorial investigation demonstrates a possible scheme of decreasing resistance start with eliminating binding materials in electrodes. Successfully fabricated binder-free electrodes show the feasibility of eliminating binding materials in electrodes. The easy access fabrication process of graphene oxide/CNT electrodes provides a chance for mass production in the industry. Solid-state electrolyte samples also give an example of making all-solid-state energy storage devices.

First Advisor

Byung H. Kim

Second Advisor

Yanfei Xu

Third Advisor

Dimitrios Maroudas

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