Methanol oxidation and direct methanol fuel cells: a selective review

This article introduces the radical approach of applying alkaline anion-exchange membranes (AAEMs) to meet the current challenges with regards to direct methanol fuel cells (DMFCs). A review of the literature is presented with regards to the testing of fuel cells with alkaline membranes (fuelled with hydrogen or methanol) and also to candidate alkaline anion-exchange membranes for such an application. A brief review of the directly related patent literature is also included. Current and future research challenges are identified along with potential strategies to overcome them. Finally, the advantages and challenges with the direct electrochemical oxidation of alternative fuels are discussed, along with how the application of alkaline membranes in such fuel cells may assist in improving performance and fuel efficiency.

https://epubs.surrey.ac.uk/1696/1/fulltext.pdf

Prospects for Alkaline Anion-Exchange Membranes in Low Temperature Fuel Cells†

https://gazi.edu.tr/posts/download?id=116871

A review of the state-of-the-art of the methanol crossover in direct methanol fuel cells

Ion-containing block copolymers hold promise as next-generation proton exchange membranes in hydrogen and methanol fuel cells. These materials’ self-assembled ordered nanostructures facilitate proton transport over a wide range of conditions, a requirement for robust fuel cell performance. In this perspective, we will present an overview of the morphology and transport properties of ion-containing block copolymers that have been studied to gain insight into the fundamental behavior of these materials and, in some cases, are targeted toward applications in fuel cells and other electrochemical devices. We will discuss the challenges associated with predicting and obtaining well-ordered morphologies in block copolymers with high ion content, particularly those with chemistries that can withstand the chemical and mechanical stresses of the fuel cell, such as aromatic backbone block copolymers. New opportunities for ion-containing block copolymers in alkaline membrane fuel cells will also be reviewed.

Block Copolymers for Fuel Cells

The direct methanol fuel cell (DMFC) has the potential to replace lithium-ion rechargeable batteries in portable electronic devices, but currently experiences significant power density and efficiency losses due to high methanol crossover through polymer electrolyte membranes (PEMs). Numerous publications document the synthesis and characterization of new PEMs for the DMFC. This article reviews this research, transport phenomena in PEMs, and experimental techniques used to evaluate new PEMs for the DMFC. Although many PEMs do not show significant improvements over Nafion®, the benchmark PEM in DMFCs, experimental results show that several new PEMs exhibit lower methanol crossover at similar proton conductivities and/or higher DMFC power densities. These results and recommendations for future research are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Parts B: Polym Phys 44: 2201–2225, 2006

Polymer electrolyte membranes for the direct methanol fuel cell: A review

Performance and modelling of a direct methanol solid polymer electrolyte fuel cell

The performance of a direct methanol fuel cell based on a Nafion® solid polymer electrolyte membrane (SPE) is reported. The fuel cell utilizes a vaporized aqueous methanol fuel at a porous Pt–Ru–carbon catalyst anode. The effect of oxygen pressure, methanol/water vapour temperature and methanol concentration on the cell voltage and power output is described. A problem with the operation of the fuel cell with Nafion® proton conducting membranes is that of methanol crossover from the anode to the cathode through the polymer membrane. This causes a mixed potential at the cathode, can result in cathode flooding and represents a loss in fuel efficiency. To evaluate cell performance mathematical models are developed to predict the cell voltage, current density response of the fuel cell.

Performance of a direct methanol fuel cell

The anodic oxidation of potassium bromide to potassium bromate is performed in an undivided cell with hydrogen evolution the major reaction at the counter electrode. The cell used is a dished electrode membrane (DEM) cell. Current density distribution, measured using a segmented electrode, shows a variation in the two principle dimensions; along the length of the electrode and over the width of the electrode. Current densities are highest at the electrolyte flow inlet and also exhibit a localized maximum along the electrode length. The variation in current density is due to the influence of electrolytic gas evolution on the effective electrolyte conductivity and mass transport and also due to the change in shape of the dished electrode, which influences mass transport, electrical potential field and flow at the cell inlet and exit.

W. Taama

Papers

Performance and modelling of a direct methanol solid polymer electrolyte fuel cell

Performance of a direct methanol fuel cell

A study of current distribution in a DEM cell during bromate formation