Nafion membranes early developments

Subsequent to these early developments of alloy electrocatalysts in the PAFC technology have been attempts to use the same in pefluorinated sulfonic acid fuel cells (solid-state membranes such as Nafion from Dupont, Dow, Asahi, and others). Yeager et al. [19] have reviewed the effect of different electrolytes on the ORR electrocatalysis. The summary of this work is that the solid-state perfluorinated acid environment offers significant advantages over phosphoric acid. These are... 

Very early hydrocarbon-based membranes tested as electrolytes in PEMECs for Gemini space missions, such as sulfonated phenol-formaldehyde resins, sulfonated poly(styrene-divinylbenzene) copolymers, and grafted polystyrene sulfonic acid membranes, were chemically weak, and therefore PEMFCs using these membranes showed poor performance and had only lifetimes of several hundred hours (LaConti et al. 2003). Nafion , a PESA membrane, was developed in the mid-1960s by DuPont (LaConti et al. 2003). It is based on an aliphatic perfluorocarbon sulfonic acid, and exhibited excellent physical properties and oxidative stability in both wet and dry states. A PEMEC stack using Nafion 120 (250- tm thickness, equivalent weight = 1,200) achieved continuous operation for 60,000 h at 43-82°C (LaConti et al. 2003, 2006). A Nafion -based PEMFC was used for the NASA 30-day Biosatellite space mission (LaConti et al. 2003). 

Solution-phase BFCs have been developed by Palmore et al., with anode and cathode compartments separated by a Nafion membrane. Starting in 1998, Palmore et al. used laccase in a mediated cathode and cascades of multiple enzymes designed to fully oxidize methanol to carbon dioxide at a mediated anode [22,29]. The cathode used in Palmore et al. s early work was ABTS, which was chosen for the value of ... 

Another approach was the synthesis of inorganic/organic composite materials to influence the properties of the membrane. An overview on the state of the art of composite perflourinated membranes is given in [15]. Infiltration of a polymer carrier material with various inorganic proton conductors is subject of a patent [16]. For operation at elevated temperature, several materials have been considered, hi an early work, Nafion /Fl3P04 showed better conductivity at temperatures above 100°C compared with blank Nation and also reduced methanol permeabihty [17]. New types of polymers are also under development for better temperature stabihty one of the most advanced examples is the high-temperature material polybenzimidazole, which usually is doped with phosphoric acid [18]. 

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