Alkaline battery, composite separator therefor
AssigneeKimberly-Clark Corporation
InventorsRobert E. Weber, Joseph Borovsky
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Abstract
A dual function, composite absorber/barrier battery separator for alkaline cells is comprised of a moderately cross-linked polyvinyl alcohol film and a flexible, fibrous and wettable absorber web, the film being semipermeable to electrolyte flow. The film is mechanically bonded to a top surface of the web in a manner so as to minimize the delays of transitions from hydrodynamic flow to diffusional flow through the separator during cell operation. The invention also includes the method of making the composite separator.
Claims14
An improved composite absorber/barrier battery separator for use in an alkaline battery cell for physically separating electrodes of said cell and for controlling the transfer of ions in an electrolyte solution during cell operation, in which said composite separator includes an absorber comprised of a flexible and fibrous substrate, resistant to strong alkali and oxidation while holding electrolyte in contact with said electrodes during electrolyte ion transfer, said improvement comprising:
- a moderately cured polyvinyl alcohol film adhered to at least one side of said absorber prepared from an aqueous coating composition comprising of:
- (a) a polyvinyl alcohol aqueous dispersion comprised of (1) a noncrosslinked polyvinyl alcohol solution, (2) inert hydrophilic fillers (3) a dispersing agent, (4) a water soluble plasticizer, and (5) a low molecular weight alcohol-water mixture;
- and
- (b) a crosslinking agent admixture comprised of;
- (1) a crosslinking agent, and (2) a catalyst;
- said dispersion and said admixture being characterized by having an insitu crosslinking property for forming a matrix of polyvinyl alcohol molecules which is insoluble in alkaline electrolyte, said crosslinking property being activated when said coating composition is cured at a desired temperature to moderately crosslink the polyvinyl alcohol with the crosslinking agent, said matrix of polyvinyl alcohol molecules being a semi-permeable film which mechanical bonds to said web along a interface of said film and said absorber web, said interface being a region formed of a portion of said film physically entangled with a portion of said web, having a thickness which is sufficiently small with respect to the thickness of said film, so as to substantially preclude delays in transitions from hydrodynamic flow through the absorber to diffusional flow through said film of electrolyte ions and masses during cell operations.
Dependencies are inferred from the claim text.