Battery cell with safety layer

1. A battery comprising:

a housing, the housing comprising first and second poles; and

a composite water-responsive safety layer comprising a polymer material and being positioned adjacent to at least one of the first and second poles, the composite water-responsive safety layer being adapted to change from a non-electronically conducting state to an electronically conducting state when contacted with an aqueous solution, the composite water-responsive safety layer further comprising at least one metal salt, wherein the composite water-responsive safety layer is disposed on an external surface of the battery.

2. The battery of claim 1 , wherein the polymer material comprises polyethylene glycols, polyethylene oxide, polyacrylic acid, polyacrylates, polyvinyl alcohols and modified polyvinyl alcohols, water-soluble acrylate copolymers, polyvinyl esters, polyvinyl pyrrolidone, pullulan, gelatin, hydroxylpropylmethyl cellulose (HPMC), low viscosity grade hydroxypropylcellulose, polysaccharides, water-soluble natural polymers, modified starches, copolymers of the foregoing, and combinations of any of the foregoing.

3. The battery of claim 1 , wherein the polymer material is biologically inert.

4. The battery of claim 1 , wherein the composite water-responsive safety layer further comprises a zero oxidation state metal powder.

5. The battery of claim 4 , wherein the metal powder is selected from the group consisting of bismuth(0) (Bi), copper(0) (Cu), iron(0) (Fe), indium(0) (In), lead(0) (Pb), nickel (0) (Ni), magnesium(0) (Mg), mercury(0) (Hg), silver (0) (Ag), tin(0) (Sn), zinc(0) (Zn), alloys thereof, and any combinations thereof.

6. The battery of claim 1 , further comprising a metal layer in contact with an exterior surface of the at least one pole.

7. The battery of claim 1 , wherein the metal layer is in contact with the negative pole (corresponding to the battery anode) and comprises a metal selected from the group consisting of bismuth(0) (Bi), indium(0) (In), lead(0) (Pb), mercury(0) (Hg), tin(0) (Sn), zinc(0) (Zn), alloys thereof, and any combinations thereof.

8. The battery of claim 1 , wherein the composite water-responsive safety layer comprises a polymer selected from polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and a combination thereof, and the metal salt comprises copper sulfate (CuSO 4 ).

9. The battery of claim 8 , wherein the composite water-responsive safety layer further comprises zinc (Zn) particles.

10. The battery of claim 8 , wherein the copper sulfate is present in an amount of at least 5 weight %, based on the total weight of the composite water-responsive safety layer.

11. The battery of claim 1 , the composite water-responsive safety layer further comprises an additive selected from a stabilizer, a porogen, and a combination thereof.

12. The battery of claim 1 , wherein the positive pole is electronically isolated from the negative pole by an insulating gasket and wherein the composite water-responsive safety layer is positioned adjacent the insulating gasket, the composite water-responsive safety layer extending between and contacting both the positive pole (corresponding to the battery cathode) and the negative pole (corresponding to the battery anode).

13. The battery of claim 12 , wherein the composite water-responsive safety layer extends between the positive pole and the negative pole continuously around a periphery of at least one of the positive pole and the negative pole.

14. The battery of claim 12 , wherein the safety layer extends between the positive pole and the negative pole around a portion of a periphery of at least one of the positive pole and the negative pole.

15. The battery of claim 1 , wherein the battery is selected from a AAAA, AAA battery, a AA battery, a B battery, a C battery, a D battery, a 9V battery, a CR2 battery, a CR123A battery, a 1/3N battery, a button cell, and a coin cell.

16. The battery of claim 1 , wherein the composite water-responsive film comprises polyvinyl acetate, copper sulfate, and copper carbonate.

17. The battery of claim 16 , wherein the composite water-responsive film further comprises polyethylene oxide.

18. A method comprising:

providing a battery housing comprising first and second poles;

forming a composite water-responsive safety layer between the first and second poles of the battery housing by depositing a composition between the poles such that the composition is adjacent to at least one of the first and second poles, the composition comprising a polymer material and at least one metal salt, the composite water-responsive safety layer being adapted to change from a non-electronically conducting state to an electronically conducting state when contacted with an aqueous solution, wherein the composite water-responsive safety layer is disposed on an external surface of the battery.

19. The method of claim 18 , wherein the polymer material comprises polyethylene glycols, polyethylene oxide, polyacrylic acid, polyacrylates, polyvinyl alcohols and modified polyvinyl alcohols, water-soluble acrylate copolymers, polyvinyl pyrrolidone, polyvinyl esters, pullulan, gelatin, hydroxylpropylmethyl cellulose (HPMC), low viscosity grade hydroxypropylcellulose, polysaccharides, water-soluble natural polymers, modified starches, copolymers of the foregoing, and combinations of any of the foregoing.

20. The method of claim 18 , wherein the composite water-responsive safety layer comprises a mixture of polyethylene glycol, copper sulfate powder, and zinc particles.

21. The method of claim 18 , wherein the composite water-responsive safety layer comprises a polymer selected from polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyethylene oxide, and a combination thereof, and the metal salt comprises copper sulfate (CuSO 4 ).

22. The method of claim 18 , further comprising depositing at least one dot of zinc metal on the negative pole prior to depositing the composition.

23. The method of claim 18 , wherein the composite water-responsive film comprises polyvinyl acetate, copper sulfate, and copper carbonate.

24. The method of claim 23 , wherein the composite water-responsive film further comprises polyethylene oxide.