Nanoporous composite, low cost, protonic membranes for direct methanol fuel cells F. Croce a , J. Hassoun b , C. Tizzani b , B. Scrosati b, * a Dipartimento di Scienze del Farmaco, Universita ` ‘d’Annunzio’, Via dei Vestini 31, 66013 Chieti, Italy b Dipartimento di Chimica, Universita ` ‘La Sapienza’, P.le A. Moro, 5 00185 Roma, Italy Received 28 March 2006; received in revised form 3 May 2006; accepted 10 May 2006 Available online 13 June 2006 Abstract New types of nanoporous, composite membranes, prepared by readapting a procedure successfully used in the lithium battery tech- nology, are here described and evaluated. The membranes are based on a polyvinylidene fluoride polymer matrix containing dispersed SiO 2 ceramic powder at nanoparticles size. The unique preparation method confers an extended porosity which favors the swelling of the acid solutions to provide a high proton conductivity. The properties of these membranes can be monitored by properly controlling the amount of the dispersed ceramic filler, to finally obtain samples which combine good conductivity with low methanol permeability. Due to these features, the selected membrane samples can be profitably used as separators in ambient temperature direct methanol fuel cells, DMFCs. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Polymer; Membrane; Composite; Proton; Fuel cells 1. Introduction Vehicle transportation represents a significant portion of world energy consumption and contribute considerably to atmospheric pollution. Thus, the development of zero or controlled emission cars is an important goal from both economical and environmental point of view. Direct methanol fuel cells, DMFCs, are suitable systems for power generation in electrotraction [1]. Similar to inter- nal combustion engines, also DMFCs utilize liquid fuel to deliver continuous power with much higher utilization effi- ciency and intrinsically lower polluting emission [2]. However, in order to be competitive within the transpor- tation market, the proposed DMFCs must be reasonably cheap and capable of delivering high power. At the present, there are still few challenging problems to be solved for reaching this goal. Among the major issues, those associ- ated to the electrolyte membrane play a crucial role. In fact, the ideal properties of a DMFC membrane are a high proton conductivity associated to a low methanol cross- over and a low cost. These properties are not totally met by the commonly used membranes which are mainly of the perfluorosulphonate type, a typical example of which is Nafion Ò . These membranes suffer by a low thermal sta- bility and a low methanol selectivity. In addition, they are the components which, together with the noble metals in the catalysts, mostly contribute to the cost of DMFCs. Thus, great R&D effort is presently devoted for a break- through in the development of membranes alternative to Nafion in terms of cost and methanol permeability [3]. Following this trend, we have directed our attention to new types of porous membranes prepared by readapting synthesis procedures proved in the nineties by Bellcore Laboratories to be successful in the lithium battery tech- nology [4]. These involve first the cast of a slurry formed by a poly(vinylidene) fluoride-chloro tetrafluoro ethylene, PVdF-CTFE, copolymer with dispersed ceramic filler and with the addition of dibutylphthalate, DBP. The DBP is 1388-2481/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.elecom.2006.05.006 * Corresponding author. Tel.: +39 6 4462866; fax: +39 6 491769. E-mail address: bruno.scrosati@uniroma1.it (B. Scrosati). www.elsevier.com/locate/elecom Electrochemistry Communications 8 (2006) 1125–1131