A Pore-Filling Electrolyte Membrane-Electrode Integrated System for a Direct Methanol Fuel Cell Application

Abstract

To develop a high performance direct methanol fuel cell, a novel electrolyte membrane is needed. This electrolyte membrane should be durable up to 130°C to improve the catalytic reaction, and the methanol crossover should be reduced. Our approach was to design a pore-filling-type polyelectrolyte membrane, where the polyelectrolyte is filled into the pores of a porous substrate. This makes an integrated system with a membrane and a catalyst layer. The porous substrate was completely inert to aqueous methanol solution and was durable at high temperature. The substrate matrix could suppress membrane swelling to reduce methanol crossover, and showed mechanical strength at high temperatures. A radical polymerization technique was employed to fabricate the pore-filling membrane. A porous silica sol-gel thin base membrane on a carbon electrode was used as a membrane-electrode integrated system. The substrate pores were filled with a poly͑acrylic acid-co-vinyl sulfonic acid͒ network. The membranes showed high proton conductivity, thermal stability, and low methanol permeation.

Sulfonated hydrocarbon membranes for medium-temperature and low-humidity proton exchange membrane fuel cells (PEMFCs)

“…g −1 ). The corresponding pore-filling membranes [245,247] exhibited proton conductivities that were much lower than that of Nafion ® 117 ( = 8 × 10 −2 S cm −1 ) under the same measurement conditions (25 • C and humid state). On the other hand, poly(acrylamide-tert-butylsulfonic acid) (PATBS) has one -SO 3 H group per monomer unit (IEC = 4.5 mequiv.…”

“…The resulting reinforced sulfonated hydrocarbon PEMs are classified into pore-filling membranes [173,[245][246][247][248][249] and sulfonated polymerimpregnated electrospun composite membranes [250,251] according to the substrate characteristics.…”

“…The substrate must simultaneously be mechanically strong enough to endure the swelling of sulfonated copolymers filling the pores in the fully hydrated state. In the early stages of pore-filling research, porous silica (e.g., SiO 2 gel) on a carbon support was used as a substrate [245]. Despite its thermal stability, SiO 2 gel was fragile and cannot form a self-supporting film structure.…”

A Porous Silicon‐Based Ionomer‐Free Membrane Electrode Assembly for Miniature Fuel Cells

“…Alternative systems, such as organic-inorganic hybrid membranes, have been proposed to avoid these problems. For instance, hybrid silica/Nafion ® membranes [6][7] or a porous silica membrane filled with sulfonated polyelectrolyte [8] have been reported, but, as yet, are not suitable in obtaining easily integrated miniature cells. Although the use of porous silicon (PS) as a gas diffusion layer [9] or as catalyst support [10][11] is not new in the case of fuel cells, recent papers [12][13] have shown the relevance of using PS as the fuel cell membrane.…”

An Oriented Nanoporous Membrane Prepared by Pulsed Laser Deposition

“…[4] However, the complexity of the processes and the residual stresses remaining in the films have considerably restricted the usefulness of such approaches. A defect-free microstructure with good mechanical strength is vital when considering applications such as processing of hybrid structures by pore filling, [5] where such oriented nanostructures might be of great benefit. Here we show that by controlled pulsed laser deposition (PLD), [6] oriented porous membranes made of uniform nanoparticles and nanochannels extending through the thickness of the membrane can be made.…”