Date of Graduation

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor/Mentor

Ang, Simon S.

Committee Member

Tian, Z. Ryan

Second Committee Member

Yu, Shui-Qing "Fisher"

Third Committee Member

Balda, Juan C.

Keywords

Electric Double Layer Capacitor; Flexible Devices; Graphene; MoS2; Supercapacitor

Abstract

Supercapacitors have attracted a lot attention due to their efficient energy storage. In comparison to batteries, supercapacitors have high capacitance, energy, and power densities per unit mass than conventional capacitors. Carbon based materials are most promising in supercapacitor application due to their outstanding physical and electrochemical behavior. In this work, a facile method to synthesize a nanocomposite electrode consisting of annealed carbon from carbon ink and MoS2 was demonstrated. Effects of various aqueous and solid electrolytes were studied. It was found that the nanocomposite electrode with 10% MoS2 and 1M Na2SO4 as the aqueous electrolyte tested using the three electrode method exhibited a capacitance of 207.5 F/g at a current density of 0.5 A/g. However, with the influence of K+ ions, the 10% MoS2 nanocomposite electrode based electric double layer (EDL) capacitor displayed a comparatively higher capacitance of 10.1 F/g at a current density of 1 A/g with 0.5 M K2SO4 as the aqueous electrolyte. The button cell EDL capacitor performance was further improved up to 50% using 1 M Na2SO4 aqueous electrolyte (15.2 F/g at a current density of 1 A/g) in comparison to using 0.5 M Na2SO4 aqueous electrolyte (4 F/g at a current density of 1 A/g). Pouch cell supercapacitors were fabricated using both aqueous and solid electrolytes which had almost similar overall performance. A MoS2/annealed carbon nanocomposite based supercapacitor with solid electrolyte which possesses capacitance and energy density of 10.6 F/g and 5.9 Wh/Kg, respectively, was demonstrated. A cylindrical cell supercapacitor was fabricated using 1M Na2SO4 as the aqueous electrolyte and yielded capacitance and energy density of 6.7 F/g and 4.9 Wh/Kg, respectively, at a current density of 1 A/g.

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