Control of Volume Resistivity in Inorganic-Organic Separators

Control of resist ivity in NASA inorganic-organic separators is achieved by incorporating small percentages of high surface area, f ine-particle sil ica with other ingredients i i i the separator coating. The volume resist ivity appears to be predictable from coating composition, that is, from the surface area of fil ler particles in the coating. The approach as been appl ied to two polymer-"p las-t icizer"-f i l ler coating systems, where the filler content of each is below the general ly acknowledged crit ical pigment volume concentration of the coating. Appl icat ion of these coating systems to 0.0254 cm thick (10 mil) fuel-cel l grade absestos heet produces inexpensive, flexible, microporous eparators that per-form at least as wel l as the original inorganic-organic concept, the Astro-power separator. The usefulness of the inorganic-organic separators developed at the Lewis Research Center for alkal ine batteries (i.e., Ag-Zn, Ni-Zn, and Ni-Cd batteries