Mussel-inspired polydopamine-treated composite electrolytes for long-term operations of polymer electrolyte membrane fuel cells

While composite proton-conductive membranes have been demonstrated to enhance the durability of polymer electrolyte membrane fuel cells (PEMFCs), preservation of homogeneous interfaces between inner components has often been a nontrivial challenge for long-term cell operations. Herein, we report mussel-inspired polydopamine as an adhesive mediator between proton-conductive sulfonated poly(ether ether ketone) (sPEEK) and mechanically stable porous polytetrafluoroethylene (PTFE) substrates. The polydopamine coating facilitates a conformal interface between both components with a large surface energy difference and enables such homogeneous membranes for long-term cell operations. The enhanced mechanical stability and stable conformation of the composite membranes were reflected by superior electrochemical performance over repeated wet/dry cycles via suppressed crack/void space formation and edge failure. The present study suggests that the mussel-inspired polymer coating is a useful scheme for various energy devices that need to deal with multiple components with different surface energies.