Improved separators for silver-hydrogen cells

The polyamide/cellophane composite separator employed in Ag/H2 cells was replaced by zirconia cloth separators coated with zirconia sol on the side facing the Ag electrode and impregnated with polyphenylene oxide (PPO). Cells containing standard and zirconia separator were given 750 charge/discharge cycles employing LEO cycling conditions at 20 then 30 C. At 30 C, the cell containing the zirconia cloth separator short circuits at cycle 680; the base line cell reaches 750 without a short circuit, although Ag concentration in the cellophane layers increases. The main problem with coated zirconia cloth is to ensure that the coating is pinhole free. The few areas where Ag diffuses through the cloth probably corresponded to pinholes or channels in the coating. This problem may be very difficult to overcome.