Application of the radiation induced grafting technology in preparing the proton exchange membranes for fuel cells

Polymer electrolyte fuel cells (PEFCs) are now in the focus as the most promising energy source for the vehicles and other mobile applications. Proton exchange membranes (PEMs) are the important component in the PEFCs, which separate the fuel gases and transport the protons. Among the PEMs, poly(perfluorosulfonic acid) (PFSA) membranes are the most widely used. However, high cost of the per-fluorinated PEMs encouraged the development of the cheaper and better fluorinated or non-fluorinated PEMs. Radiation induced grafting of functional monomers into polymer films or membranes and successive sulfonation was designed as an alternative route to obtain the PEMs for PEFC applications. Typically, styrene and co-monomers like divinylbenzene were grafted into the fluorinated polymer films or membranes. Under this method, it is facilitate to prepare thin PEM with relative high ion exchange capacity (IEC) value. Also, long term single cell running result showed that this kind of PEM has acceptable performance and life time. Experiment results demonstrated that this method is quite promising.