Separators for electrochemical cells

Abstract

Provided are separators for use in an electrochemical cell comprising (a) an inorganic oxide and (b) an organic polymer, wherein the inorganic oxide comprises organic substituents. Preferably, the inorganic oxide comprises an hydrated aluminum oxide of the formula Al2O3.xH2O, wherein x is less than 1.0, and wherein the hydrated aluminum oxide comprises organic substituents, preferably comprising a reaction product of a multifunctional monomer and/or organic carbonate with an aluminum oxide, such as pseudo-boehmite and an aluminum oxide. Also provided are electrochemical cells comprising such separators.

Description

Claims

1. A separator for an electrochemical cell, wherein said separator comprises a microporous layer comprising (a) an inorganic oxide and (b) an organic polymer, wherein said inorganic oxide comprises organic substituents.

2. The separator of claim 1, wherein said inorganic oxide is a hydrated aluminum oxide of the formula Al2O3.xH2O, wherein x is less than 1.0, and wherein said hydrated aluminum oxide comprises organic substituents.

3. The separator of claim 2, wherein x is less than 0.8.

4. The separator of claim 2, wherein x is less than 0.6.

5. The separator of claim 1, wherein said organic polymer comprises a polymer selected from the group consisting of polyvinyl alcohols, polyethylene oxides, polyvinyl pyrrolidones, and cellulosic polymers.

6. The separator of claim 1, wherein said organic substituents comprise a reaction product of a multifunctional monomer with an inorganic oxide.

7. The separator of claim 6, wherein said multifunctional monomer is a divinyl ether.

8. The separator of claim 6, wherein said multifunctional monomer is a divinyl ether of an ethylene glycol.

9. The separator of claim 1, wherein said organic substituents comprise a reaction product of an organic carbonate with an inorganic oxide.

10. The separator of claim 9, wherein said organic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, butylenes carbonate, dimethyl carbonate, ethylmethyl carbonate, vinylene carbonate, dipropyl carbonate, dibutyl carbonate, and diethyl carbonate.

11. The separator of claim 1, wherein the pore volume of said separator is 48 percent to 62 percent, the elastic modulus of said separator is greater than 30,000 kg/cm2, and the elongation of said separator at break is greater than 5 percent.

12. The separator of claim 1, wherein the pore volume of said separator is 48 percent to 62 percent, the elastic modulus of said separator is greater than 30,000 kg/cm2, and the elongation of said separator at break is greater than 10 percent.

13. The separator of claim 1, wherein said separator does not melt at temperatures lower than 300° C.

14. An electrochemical cell comprising an anode, a cathode, and a separator interposed between said anode and said cathode, wherein said separator comprises a microporous layer comprising (a) an inorganic oxide and (b) an organic polymer, wherein said inorganic oxide comprises organic substituents.

15. The cell of claim 14, wherein said inorganic oxide comprises a hydrated aluminum oxide of the formula Al2O3.xH2O, wherein x is less than 1.0, and wherein said hydrated aluminum oxide comprises organic substituents.

16. The cell of claim 14, wherein the anode active material of said anode is lithium.

17. The cell of claim 14, wherein said cell is a secondary cell.

18. The cell of claim 14, wherein said cell is a primary cell.

19. An electrochemical cell comprising an anode, a cathode, and a separator interposed between said anode and said cathode, wherein said separator comprises a microporous layer comprising (a) an inorganic oxide and (b) an organic polymer, wherein said inorganic oxide comprises a reaction product of a divinyl ether and/or an organic carbonate with an inorganic oxide.

20. The cell of claim 19, wherein said inorganic oxide is a hydrated aluminum oxide of the formula Al2O3.xH2O wherein x is less than 1.0, and wherein said hydrated aluminum oxide comprises a reaction product of a divinyl ether and/or an organic carbonate with an aluminum oxide selected from the group consisting of pseudo-boehmites and hydrated aluminum oxides.