Preparation of Nano‐Structured Polymeric Proton Conducting Membranes for Use in Fuel Cells

Abstract

We briefly discuss the state of the art of polymer electrolyte membrane fuel cells and suggest that the main obstacles to the commercial development of these fuel cells are essentially the high costs and poor characteristics of present proton conducting membranes. A strategy for the preparation of improved nanocomposite membranes based on the introduction of proton conducting lamell? in the polymeric matrix of present ionomeric membranes is then discussed. Due to their high proton conductivity (in some cases even higher than 10(-1) S cm(-1)), tailor made lamellae obtained by exfoliation of superacid metal (IV) phosphonates are particularly suitable for the preparation of these hybrid membranes. The expected positive influence of the dispersed lamellae on important properties of proton conducting membranes, such as swelling, mechanical resistance, proton transport, and diffusion of methanol, are also discussed. The methods used to obtain good lamellar dispersions into ionomeric polymers and the preparation and main characteristics of some hybrid membranes are also briefly described. The presence of nanoparticles of metal phosphonates in the electrodic interfaces Nafion/Pt already considerably improves the electrochemical characteristics of fuel cells in the temperature range 80-130 degrees C. The increased working temperature of the fuel cell considerably reduces CO poisoning of the platinum electrodes and allows better control of the cooling system, thus overcoming important obstacles to the development of medium temperature PEM fuel cells.

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

“…However, most of thesePEMs possess similar transport properties to Nafion® 61. Other PEMs developed in the literature for the DMFC constitute a variety of designapproaches, such as the synthesis of newionic (sulfonic acid) random and block copolymers,21, 23, 24, 26, 28, 30, 31, 36, 43–46, 48, 51, 57, 63–72 graft copolymerization of ionic polymers unto hydrophobic membranes,15, 16, 34, 52, 73 blending ionic and nonionic polymers,13, 20, 17, 49, 53, 54, 57, 58, 74–88 the synthesis of interpenetrating networks of ionic and nonionic polymers,42, 50, 89–99 incorporating a variety of fillers (e.g., silica, montmorillonite) into ionic polymer membranes,12, 14, 18, 19, 22, 25, 27, 29, 33, 37–39, 41, 47, 92, 100–118 and coating ionic polymer membranes with thin barrier coatings 12, 32, 35, 40, 80, 119–126. The subsections below highlight findings from these investigations.…”

“…Polymer membranes containing micrometer to nanometer size fillers (composite membranes) have been explored intensely for the DMFC 12, 14, 18, 19, 22, 25, 27, 29, 33, 37–39, 41, 47, 100–118. A variety of fillers, including silica,18, 19, 38, 41, 50, 105, 115 zirconium phosphate,109 phosphotungstic acid,100 molybdophosphoric acid,112 Aerosil (silicon dioxide powder),112 ORMOSILS (organically modified silicates),22 silane‐based fillers,22 titanium oxide,109 hydroxyapatite,104 laponite,117 montmorillonite,14, 47, 110 zeolites,114 and palladium,116 have been incorporated in a number of different polymer membranes including Nafion®.…”

Physical Chemistry of Intercalated System

“…However, this system is unstable: already at 90 C MoS 2 catalyses decomposition of PEO, depending on its molecular mass and content of a composite causing a loss in conductivity of the system. A replacement of PEO by PAN causes formation of more stable [Li 0.6 MoS 2 (PAN) 1.2 · 0.5H 2 O] system [377] having mixed electronic conductivity [378,379].…”

Starch/zirconium phosphate composite films: Hydration, thermal stability, and mechanical properties

“…In particular, composites based on ZrP should benefit from the presence of the hydroxyls of the monohydrogen phosphate groups that are expected to interact with the starch functional groups more strongly than the oxygen atoms belonging to the layer surface of TOT clays. ZrP and zirconium phosphonates have already been studied as layered fillers of both ionomers (polymers with fixed charges), especially for applications in polymer electrolyte fuel cells 20–27, and neutral matrices 28–33. The results obtained so far have shown an increase in the elastic modulus and thermal stability of the composite materials in comparison with the neat polymer matrix, together with an improvement of the barrier properties, especially with highly exfoliated and high aspect ratio ZrP nanoplatelets.…”