Nanocrystalline oxides improve the performances of Polymeric Electrolytes.

Environmental problems lead to the need for new technologies in the fields of energy production and storage for sustainable development, to reduce the pollutant emissions from fossil fuel combustion [1]. Among the possible systems investigated, fuel cells seem to be very promising as electrochemical power sources for application in portable technology and in electric vehicles, in particular polymeric electrolyte fuel cells (PEFCs) [2]. On the other hand lithium ion batteries are already commercialized for electronic products, although improvement is needed for other applications (with the use of solid electrolytes) [3]. These electrochemical devices are based on polymeric electrolyte membranes, which use has been reported also for biomedical devices such as cardiac pacemakers or neurostimulators [4]. Polymer electrolytes consist of a polymer matrix into which a salt is dissolved. The ionic transport is generally described as the ionic species being moved through the electrolyte by the motion of the polymer chains. When a solvent is added to the polymer matrix the systems are called polymer gel electrolytes: the solvent improves the ionic mobility either favoring segmental motions of the polymer chains or becoming itself the medium for ionic transport [5,6]. Conductivity may be due to the motion of different ions, such as protons for fuel cells or lithium ions in batteries. The peculiar properties of these materials has made them the subject of numerous investigations, however several technological problems are still to be solved for specific applications. A possible strategy is the use of composites; composite materials have shown in fact the ability to develop new or multifunctional properties when materials with differing properties are integrated together [7]. For instance, the addition of inorganic fillers has been demonstrated to be effective in improving the ionic conductivity, mechanical strength and thermal stability of polymeric electrolyte systems [8]. Moreover, the reduction in size at the nanometric level have shown the possibility to derive unique physico-chemical properties of materials [9]. The uniform dispersion of nano-sized particles as fillers in polymers can lead to an ultralarge interfacial area between the constituents per volume of material, resulting in the development of new classes of materials with unique structure [10]. In this paper we show how the development of nanocomposite materials prepared by filling polymeric matrixes with nanocrystalline oxides is effective in improving the performances of membranes for Direct Methanol Fuel Cells (DMFC), lithium ion polymeric batteries and electrodes for electrophysiological measurements. The approach of using nanocomposite membranes seems to be quite versatile given that it was successful both for H+ and Li+ conductors and with different types of polymers.