Results And Discussion

Among four different matrix films employed for styrene grafting, only ETFE matrix films gave electrolyte properties necessary for fiiel cells, resulting in cell performance which was comparable or superior to conventional perfluorosulfonic acid membranes. The most difficult problem we encountered with other matrix films PTFE, FEP, and PFA is the lack of mechanical strength. With PTFE and PFA, we could not prepare electrolyte membranes which had both electrical conductivity as high as the conventional membranes and enough mechanical strength enabling cell fabrication. Appreciable decrease in strength was found for these matrix films after gamma ray irradiation of even 20 kGy, followed by the increase in brittleness after subsequent reactions. Although the above problem was relatively lightened with FEP, we often encountered the difficulties such as membrane tearing during hot pressing or cell operation, and rapid increase in electrical resistance in the time range of several tens of hours. Thus we chose ETFE as a matrix film for further work. Table 1 shows some of properties of IMRA MEMBRANE.

Table 1. Properties of IMRA MEMBRANE

Thickness (nm) 75nmin dry

Ion exchange capacity 2.1 meq/g (EW: 480)

Resistance 0.3 ii-cm2 in 1M NaCl at 25 'C at 1000 Hz

Figure 1 shows the comparison in polarization characteristic between IMRA MEMBRANE and a conventional perfluorosulfonic acid membrane.

0 0

Post a comment