Crosslinking and grafting of polyetheretherketone film by radiation techniques for application in fuel cells

An aromatic hydrocarbon polymer electrolyte membrane (PEM) was prepared by direct modification of polyetheretherketone (PEEK) film using the radiation-induced crosslinking and grafting techniques. The crosslinking structure induced by the electron-beam irradiation enhanced the insolubility of the PEEK base film. The film shape of the crosslinked PEEK (cPEEK) was well maintained under sulfonation. A small amount of divinylbenzene (DVB) was introduced into the cPEEK film to enhance the radiation-induced styrene-grafting. The styrene-grafted film was sulfonated under a mild sulfonation condition to obtain the PEM. The PEM with different ion exchange capacity (IEC) was prepared by changing the grafting yield of styrene. The new PEM exhibited lower methanol permeability and higher mechanical properties, and was proven to be durable in a direct methanol fuel cell (DMFC) at high temperature, reaching a high maximum power density of 106 mW cm−2 at 95 °C.