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URN etd-0416118-173240
Author Chih-yu Wen
Author's Email Address No Public.
Statistics This thesis had been viewed 5332 times. Download 0 times.
Department Electrical Engineering
Year 2017
Semester 2
Degree Ph.D.
Type of Document
Language English
Title Study of supercapacitor fabricated with composite electrodes and gel polymer electrolyte
Date of Defense 2018-05-02
Page Count 106
Keyword
  • Supercapacitor
  • Tungsten oxide
  • Mesocarbon microbeads
  • Energy density
  • Composite electrode
  • Abstract This study separately mixed Ni(CH3COO)2 and H2O4W solutions with mesocarbon microbeads (MCMBs), filtered the resulting solution, and then subjected the carbon paste to heat treatments to give rise to composite carbon powder. The powder was then mixed with an adhesive and then applied to a conductive carbon (CC)/ITO glass substrate, which completed the fabrication of a composite electrode for supercapacitors. Gel polymer electrolytes (GPEs) were made using lithium salts LiClO4 and LiBOB in propylene carbonate (PC) solvent. The resulting electrolytes were tested using AC impedance spectroscopy and galvanostatic charge-discharge efficiency tests to determine the influence of the lithium salt used on the capacitance properties of the GPE. Finally, charge-discharge efficiency tests, ambient temperature tests, and lifetime tests were conducted on the supercapacitor.
    The results show that a 0.75-M H2O4W solution paired with a 100C heat treatment to produce a composite-structured carbon powder in addition to 25 wt.% carbon black and 2 wt.% adhesive results in a composite electrode with the best capacitance properties. Its specific capacitance in a electrolyte (1 M LiClO4) was 249 F∙g-1. The GPE (Sample 4) made with 8 wt.% LiClO4 and 30 wt.% Ionic liquid (IL) presented lower bulk impedance, lower electrolyte-electrode interface impedance, a lower device decline rate, and a higher specific capacitance. The charge-discharge tests revealed that within the voltage range of 0 V to 2.5 V and a charge/discharge current density of 0.3 A∙g-1, the WO3/MCMB presented the optimal specific capacitance of 234.22 F∙g-1. From this results, It could be calculated that the energy density was 293 Wh∙kg-1, and the power density was 105.4 kW∙kg-1 (discharge current @0.03 A). The results therefore demonstrate that the composite electrode fabricated in this study exist good performance capacitance. Furthermore, the composite electrode presented near-100% charge-discharge efficiency and good adhesion between the electrode materials and the substrate after 1,000 charge-discharge cycles in the galvanostatic charge-discharge efficiency tests and service-life tests.
    Advisory Committee
  • Chih-ming Wang - chair
  • Hao-ying Lu - co-chair
  • Shoou-jinn Chang - co-chair
  • Cheng-fu Yang - co-chair
  • Mau-phon Houng - co-chair
  • Yeong-her Wang - co-chair
  • Feng-renn Juang - co-chair
  • Teen-hang Meen - co-chair
  • Ying-chung Chen - advisor
  • Files
  • etd-0416118-173240.pdf
  • Indicate in-campus at 2 year and off-campus access at 2 year.
    Date of Submission 2018-05-16

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