<fmt:message key='jsp.layout.header-default.alt'/>  
 

DSpace@UM >
Faculty of Science >
PhD Theses : Science >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1812/567

Title: Performance characteristics of carbon based electrical double layer capacitors with PVA and PVA-Cellulose hybrid electrolytes
Authors: Mohd Azman Hashim @ Ismail
Keywords: Hybrid electrolytes
Solid Polymer Electrolyte
SPE
PVA
PVA-Cellulose
Carbon characteristics
Issue Date: 2008
Publisher: University Malaya
Abstract: The main focus of this work is to develop a high conducting solid polymer electrolyte (SPE). Poly(vinyl Alcohol), PVA was used as a host and H3PO4 as the ionic dopant. The highest electrically conducting sample in the PVA-H3PO4 (nonhybrid) electrolyte system has composition PVA + 50 wt% H3PO4 (P50H50). The room temperature electrical conductivity is 9.70 x 10-6 S cm-1. A higher electrical conductivity can be achieved by introducing a Whatman® filter paper which acts as a support to the PVA electrolyte and because of its porous nature allows more H3PO4 acid to be loaded into the system. In the PVA-H3PO4 which is considered as the non-hybrid system, the maximum amount of acid that can be loaded is 50 wt%. For the hybrid system, i.e. PVA-filter paper-H3PO4 70 wt% acid can be loaded into the system. The mechanical strength of the system has improved and the highest electrically conducting sample in the PVA-H3PO4-filter paper system has been designated P30H70-C with conductivity 1.04 x 10-4 S cm-1. Three EDLCs were fabricated using the two polymer electrolyte systems. Using PVAH3PO4 (non-hybrid) electrolyte system with the highest conductivity at room temperature sandwiched between two activated carbon electrodes (BP20) a specific capacitance of 4.89 Fg-1 and the internal resistance of 4.13 Ω cm-2 has been obtained. The second EDLC used the same electrodes but different polymer electrolyte system. Cellulose hybrid electrolyte system was introduced to replace PVA-H3PO4 (non-hybrid) electrolyte system. Cellulose hybrid electrolyte is used because the conductivity is higher than PVA-H3PO4 (non-hybrid system). Chargedischarge characteristics showed the specific capacitance increased to 7.73 Fg-1 and internal resistance reduced to 2 Ω cm-2. The third EDLC used the same cellulose hybrid electrolyte and activated carbon electrodes soaked in H3PO4. Charge-discharge characteristics showed the specific capacitance increased to 31.47 Fg-1 and internal resistance reduced to 1 Ω cm-2. The increase in specific capacitance is contributed by the diffusive layer to the entire electrodes. The double layers formed capacitors which are overall connected in a parallel arrangement such that the total capacitance adds up and contribute to a higher capacity. For a working voltage for this EDLC is 1 V and the efficiency is between 80 to 97 %.
Description: Thesis (PhD) -- Faculty of Science, University of Malaya, 2008.
URI: http://dspace.fsktm.um.edu.my/handle/1812/567
Appears in Collections:PhD Theses : Science

Files in This Item:

File Description SizeFormat
Thesis-Mohd Azman Hashim @ Ismail.pdfThesis Text16.88 MBAdobe PDFView/Open


This item is protected by original copyright



Your Tags:

 

  © Copyright 2008 DSpace Faculty of Computer Science and Information Technology, University of Malaya . All Rights Reserved.
DSpace@UM is powered by MIT - Hawlett-Packard. More information and software credits. Feedback