Comparative Studies of Methanol Crossover and Cell Performance for a DMFC

Abstract

Fuel (methanol) crossover through the polymeric electrolyte membrane in a single direct methanol fuel cell (DMFC) was determined by monitoring the amount of CO2 produced from methanol oxidation. Instead of measuring CO2 from only the cathode by a conventional method, the amounts of CO2 at both of the cathode and the anode were determined in the present study. Gravimetric determination of BaCO3 was employed to accurately analyze the amount of CO2. The equivalent current of methanol crossover can be calculated from the discharge current of the fuel cell and the sum of dry BaCO3 precipitate collected at the anode and the cathode exhausts. The common experimental deviation of measuring methanol crossover caused by CO2 permeation through polymeric electrolyte membrane can be corrected with the proposed method. These data of methanol crossover were compared with the data of single cell polarization behaviors at different methanol concentrations and different temperatures. The energy density of the DMFC is not only dependent on the cell discharge performance but also significantly dependent on the faradaic efficiency that is directly linked to methanol crossover. Under the optimized operating conditions, 1.0 M methanol at 60°C, the DMFC has an energy density of 1800 Wh/kg based on pure methanol. © 2003 The Electrochemical Society. All rights reserved.

Natural and synthetic solid polymer hybrid dual network membranes as electrolytes for direct methanol fuel cells

“…From Eq. 7, equivalent current (i pmtMeOH, mA cm −2 ) for methanol crossover from anode to cathode side was determined [53]. The aforesaid procedure was carried out under OCV condition, and corresponding methanol crossover rates were estimated.…”

“…Based on the results of proton conductivity and methanol permeability, the electrochemical selectivity values for all the membranes were obtained using Eq. 8 as given below [53]:…”

Capillary-driven pumping for passive degassing and fuel supply in direct methanol fuel cells

“…Since the aim of the present paper is to present a general approach for passive degassing and fuel supply in DMFCs, the reference value used to evaluate the pumping mechanism is the methanol consumption by the MOR only. However, Jian and Chu 2004 reported that methanol consumption by crossover can exceed the consumption by the MOR by far. Chan et al (2008) studied crossover in a specific passive DMFC in which the crossover flow was estimated to be 2.7 times higher than the consumption by the MOR.…”

“…Despite this potential, the DMFC still faces significant drawbacks. In addition to methanol crossover (Jian and Chu 2004), a low catalytic activity of the methanol reaction because of CO poisoning (Park et al 2004) and flooding of the cathode (Lu and Wang 2004), the efficient removal of carbon dioxide bubbles from the anode is critical (Yang and Zhao 2005) and has thus been studied experimentally Yang et al 2005a, b) as well as theoretically (Fei et al 2008). At the anode, CO 2 bubbles are generated as a reaction product of the methanol oxidation reaction (MOR) and may block channels, hinder fuel supply and cause the DMFC to malfunction.…”

Einfluss der Reinigung und Funktionalisierung von Kohlenstoff‐Nanoröhren auf deren katalytische Eigenschaften in der Direct Methanol Fuel Cell‐Anode

“…Die DMFC ist jedoch aufgrund der kinetischen Hemmung der Methanol-Oxidation an PtRu [3] sowie durch die Permeation von Methanol zur Kathode (Methanol-Crossover) [4] in ihrer Leistung stark eingeschränkt. Eine Ursache für die gehemmte Kinetik der MeOH-Oxidation und die damit verbundenen hohen Überspannungen, ist die Adsorption von CO und anderen Zwischenprodukten an der Katalysatoroberfläche [5].…”