Separator for a battery having a zinc electrode

Abstract

The instant invention is a separator for a battery having a zinc electrode. The battery separator according to the instant invention includes a microporous membrane, and a coating on at least one surface of the microporous membrane. The coating includes a mixture of 25-40 weight % polymer and 60-75 weight % surfactant combination. The polymer is cellulose acetate, and the surfactant combination includes a first surfactant and a second surfactant. The first surfactant, preferably, has an active ingredient selected from the group consisting of organic ethers, and the second surfactant is, preferably, an oxirane polymer with 2-ethylhexyl dihydrogen phosphate.

1 . A battery separator comprising: 
 a microporous membrane; and    a coating on at least one surface of said membrane, wherein said coating comprising a mixture of 25-40 weight % polymer and 60-75 weight % surfactant combination, wherein said polymer being cellulose acetate, and said surfactant combination comprising a first surfactant and a second surfactant, said first surfactant having an active ingredient selected from the group consisting of organic ethers, said second surfactant being an oxirane polymer with 2-ethylhexyl dihydrogen phosphate.    
     
     
         2 . The separator according to  claim 1 , wherein said first surfactant and said second surfactant having a 1:1 weight ratio.  
     
     
         3 . The separator according to  claim 1 , wherein said first surfactant and said second surfactant having a 1:3 weight ratio.  
     
     
         4 . The separator according to  claim 1 , wherein said first surfactant and said second surfactant having a 3:1 weight ratio.  
     
     
         5 . The separator according to  claim 1 , wherein said cellulose acetate having about 2.5 acetyl groups per glucose.  
     
     
         6 . The separator according to  claim 1 , wherein said coating being on both surfaces of said membrane.  
     
     
         7 . The separator according to  claim 6 , wherein said coating having a surface density in the range of 0.30 to 0.43 mg/cm 2 .  
     
     
         8 . The separator according to  claim 6 , wherein said coating having a surface density in the range of 0.31 to 0.38 mg/cm 2 .  
     
     
         9 . The separator according to  claim 6 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator having an electrical resistance of ≦10 milliohms-inch 2 .  
     
     
         10 . The separator according to  claim 6 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator having an electrical resistance in the range of 7.7 to 10 milliohms-inch 2 .  
     
     
         11 . The separator according to  claim 6 , wherein said separator being adapted for wetting by an aqueous electrolyte.  
     
     
         12 . The separator according to  claim 11 , wherein said separator being freshly coated, and said separator being wetted within 8 seconds or less.  
     
     
         13 . The separator according to  claim 11 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator being wetted within 1 second or less.  
     
     
         14 . The separator according to  claim 11 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator being wetted instantaneously.  
     
     
         15 . The separator according to 6, wherein said membrane having a thickness of less than 1.5 mils.  
     
     
         16 . The separator according to  claim 6 , said separator having an effective average pore size of less than 0.045 micron.  
     
     
         17 . A battery having a zinc electrode comprising: 
 a first electrode;    a second electrode;    an electrolyte; and    a separator, said separator being disposed between said first electrode and said second electrode and said electrolyte being in communications with said electrodes via said separator;    wherein said separator comprises; 
 a microporous membrane; and  
 a coating on at least one surface of said membrane, wherein said coating comprising a mixture of 25-40 weight % polymer and 60-75 weight % surfactant combination, wherein said polymer being cellulose acetate, and said surfactant combination comprising a first surfactant and a second surfactant, said first surfactant having an active ingredient selected from the group consisting of organic ethers, said second surfactant being an oxirane polymer with 2-ethylhexyl dihydrogen phosphate.  
   
     
     
         18 . The battery according to  claim 17 , wherein said first surfactant and said second surfactant having a 1:1 weight ratio.  
     
     
         19 . The battery according to  claim 17 , wherein said first surfactant and said second surfactant having a 1:3 weight ratio.  
     
     
         20 . The separator according to  claim 17 , wherein said first surfactant and said second surfactant having a 3:1 weight ratio.  
     
     
         21 . The battery according to  claim 17 , wherein said cellulose acetate having about 2.5 acetyl groups per glucose.  
     
     
         22 . The battery according to  claim 17 , wherein said coating being on both surfaces of said membrane.  
     
     
         23 . The battery according to  claim 22 , wherein said coating having a surface density in the range of 0.30 to 0.43 mg/cm 2 .  
     
     
         24 . The battery according to  claim 22 , wherein said coating having a surface density in the range of 0.31 to 0.38 mg/cm 2 .  
     
     
         25 . The battery according to  claim 22 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator having an electrical resistance of ≦10 milliohms-inch 2 .  
     
     
         26 . The battery according to  claim 22 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator having an electrical resistance in a range of 7.7 to 10 milliohms-inch 2 .  
     
     
         27 . The battery according to  claim 22 , wherein said separator being adapted for wetting by an aqueous electrolyte.  
     
     
         28 . The battery according to  claim 27 , wherein said separator being freshly coated, and said separator being wetted within 8 seconds or less.  
     
     
         29 . The battery according to  claim 27 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator being wetted within 1 second or less.  
     
     
         30 . The battery according to  claim 27 , wherein said separator being stored for a period not less than 22 days and not exceeding 256 days at 70° C., and said separator being wetted instantaneously.  
     
     
         31 . The battery according to  claim 22 , wherein said membrane having a thickness of less than 1.5 mils.  
     
     
         32 . The battery according to  claim 22 , said separator having an effective average pore size of less than 0.045 micron.