Separator for a battery having a zinc electrode
View Patent ↗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 for a nickel-zinc battery comprising:
a microporous membrane comprising a microporous hydrophobic, polyolefinic polymer film having a thickness of less than 1.5 mils and having an effective average pore size of less than 0.045 micron; and
a coating of cellulose acetate and a surfactant combination on at least one surface of said membrane and having a surface density in the range of 0.30 to 0.43 mg/cm 2 , said coating comprising a mixture of 25-40 weight % of the cellulose acetate and 60-75 weight % of the surfactant combination comprising a first surfactant having an active ingredient selected from the group consisting of organic ethers and a second surfactant being an oxirane polymer with 2-ethylhexyl dihydrogen phosphate, said cellulose acetate having about 2.5 acetyl groups per glucose, and
the separator having an electrical resistance of ≦21.6 mΩ-in 2 and being wetted within 3 seconds or less.
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 coating being on both surfaces of said membrane.
6. The separator according to claim 5 , wherein said coating having a surface density in the range of 0.31 to 0.38 mg/cm 2 .
7. The separator according to claim 1 , 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 .
8. The separator according to claim 1 , 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 .
9. The separator according to claim 1 , 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 by an aqueous electrolyte.
10. The separator according to claim 1 , wherein said first surfactant being a nonylphenoxypoly (ethyleneoxy) ethanol.
11. The separator according to claim 1 , wherein said polyolefinic polymer is polypropylene.
12. A nickel-zinc battery 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,
said separator comprises
a microporous membrane comprising a microporous hydrophobic, polyolefinic polymer film having a thickness of less than 1.5 mils and having an effective average pore size of less than 0.045 micron, and
a coating of cellulose acetate and a surfactant combination on at least one surface of said membrane and having a surface density in the range of 0.30 to 0.43 mg/cm 2 , said coating comprising a mixture of 25-40 weight % of the cellulose acetate and 60-75 weight % of the surfactant combination comprising a first surfactant having an active ingredient selected from the group consisting of organic ethers and a second surfactant being an oxirane polymer with 2-ethylhexyl dihydrogen phosphate, said cellulose acetate having about 2.5 acetyl groups per glucose, and
the separator having an electrical resistance of ≦21.6 mΩ-in 2 and being wetted within 3 seconds or less.
13. The battery according to claim 12 , wherein said first surfactant being a nonylphenoxypoly (ethyleneoxy) ethanol.
14. The battery according to claim 12 , wherein said first surfactant and said second surfactant having a 1:1 weight ratio.
15. The battery according to claim 12 , wherein said first surfactant and said second surfactant having a 1:3 weight ratio.
16. The separator according to claim 12 , wherein said first surfactant and said second surfactant having a 3:1 weight ratio.
17. The battery according to claim 12 , wherein said coating being on both surfaces of said membrane.
18. The battery according to claim 17 , wherein said coating having a surface density in the range of 0.31 to 0.38 mg/cm 2 .
19. The battery according to claim 12 , 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 .
20. The battery according to claim 12 , 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 by an aqueous electrolyte.