Search

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol. [ABSTRACT FROM AUTHOR]

A novel linear non-fluorinated sulfonimide functionalized polyamide (SPA) polymer electrolyte was successfully synthesized via an aromatic sulfonimide monomer with superior thermal stability and superacidity. The aromatic sulfonimide remains stable below 220 °C. To fabricate membranes with strong mechanical strength and dimensional stability, the polymer was blended with various quantities of PVdF. The PVdF/SPA blend membranes exhibit an excellent capacity of water uptake and high dimensional stability. However, their proton conductivity was found to be substantially lower than that of Nafion 211. Analysis on the SEM images of the PVdF/SPA blend membranes reveals that the low proton conductivity is primarily caused by the large pore structures (>1 μm), which lead to breakdown of the continuous proton transport channels. [ABSTRACT FROM AUTHOR]

We design and successfully synthesize non-fluorinated polyamides with controlled crosslinking using sulfonimide as a bi-functional linker to interconnect polymer backbones and as a bridge for proton conduction. We show that the bi-functional linkers are highly beneficial not only for mechanical enforcement of the proton exchange membranes but also for enhancement of water retention capacity. With an appropriate degree of crosslinking, higher water retention capacity than that of commercial Nafion membranes can be obtained. The maximum proton conductivity of the membranes is found to be as high as 0.139 S cm −1 at 80 °C, almost the same as that of a Nafion 117 membrane. Excellent performance with the bi-functional polymer membranes in an air-breathing direct methanol fuel cell prototype, comparable to the performance of a Nafion 117 membrane, is demonstrated. [ABSTRACT FROM AUTHOR]