Identifier

etd-11052006-193341

Degree

Master of Science in Electrical Engineering (MSEE)

Department

Electrical and Computer Engineering

Document Type

Thesis

Abstract

A primary goal of this work is to develop a novel liquid-based microscale fuel cell using non-noble metal catalysts. The developed fuel cell is based on a membraneless structure. The operational complications of a proton exchange membrane lead the development of a fuel cell with the membraneless structure. Non-noble metals with relatively mild catalytic activity, nickel hydroxide and silver oxide, were employed as anode and cathode catalysts to minimize the effect of cross reactions with the membraneless structure. Along with nickel hydroxide and silver oxide, methanol and hydrogen peroxide were selected as a fuel at the anode and an oxidant at the cathode. Using such a liquid-phase fuel and oxidant, an all-liquid system can be achieved and the effect of by-products becomes less significant. The electrochemical reactions of methanol and hydrogen peroxide at nickel hydroxide and silver oxide were electrochemically analyzed using cyclic voltammetry. The methanol and hydrogen peroxide fuel cell concept was experimentally validated using a macroscale fuel cell with the membraneless structure. Also, with the macroscale fuel cell, the effect of operational conditions was examined including the catalyst surface conditions, fuel mixture composition, and distance between anode and cathode. Within macroscale distances, a shorter distance between anode and cathode resulted in a higher fuel cell output power. Microscale fuel cells with the membraneless structure were also developed. Four different designs, 10, 20, 50, and 100 ìm width and spacing of interdigitated microelectrodes, were compared to investigate the distance effect in microscale distances. With a fuel mixture flow rate of 200 µl/min, a maximum output power density of 28.73 ìW/cm2 was achieved from the 10 ìm design, which was nearly three times higher than the 100 ìm design. Besides, the microfluidic behavior of the microscale fuel cell was tested with different fuel mixture flow rates. The developed microscale fuel cell features no proton exchange membrane, inexpensive catalysts, and simple planar structure, which enables high design flexibility and easy integration of the microscale fuel cell into actual microfluidic systems and portable applications.

Date

2006

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Jin-Woo Choi

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