Abstract: A battery-plate separator system includes three layers in face-to-face relationship, the first and third layers including a porous mat of randomly oriented fibers, and, between the first and third layers, a second layer comprising a porous organic polymeric sheet with tortuosity and pores sufficiently small to substantially block penetration by metallic particles. A storage battery includes a plurality of positive lead peroxide elec-trodes, a plurality of negative metallic lead electrodes, and the same three-layer separator system in a closed case with a body of electrolyte to which the system is inert, that is absorbed by the separator system, and that is maintained in contact with the electrodes.