Separators for electrochemical cells
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. Also provided are electrochemical cells comprising such separators.
1. An electrochemical cell comprising:
an anode,
a cathode, and
an electrolyte element interposed between the anode and the cathode, the electrolyte element comprising:
(a) a separator comprising:
a hydrated aluminum oxide, and
an organic polymer that is covalently bonded to at least a portion of said hydrated aluminum oxide, and
(b) an electrolyte selected from a group consisting of liquid organic electrolytes, gel polymer electrolytes, and solid polymer electrolytes.
2. The electrochemical cell of claim 1 , wherein the separator is laminated to the anode.
3. The electrochemical cell of claim 1 , wherein the separator is laminated to the cathode.
4. The electrochemical cell of claim 1 , wherein said hydrated aluminum oxide comprises one or more of boehmite and an organically-modified aluminum oxide.
5. The electrochemical cell of claim 4 , wherein said hydrated aluminum oxide further comprises organic substituents.
6. The electrochemical cell of claim 1 , wherein said hydrated aluminum oxide is of a formula Al 2 O 3 ·xH 2 O, wherein x is in a range of 0.8 to 1.5.
7. The electrochemical cell of claim 6 , wherein said organic polymer is a polyethylene oxide.
8. The electrochemical cell of claim 6 , wherein said hydrated aluminum oxide is of the formula Al 2 O 3 ·xH 2 O, wherein x is in a range of 0.8 to less than 1.0.
9. The electrochemical cell of claim 6 , wherein said hydrated aluminum oxide is of the formula Al 2 O 3 ·xH 2 O, wherein x is in a range of 1.0 to 1.5.
10. The electrochemical cell of claim 1 , wherein the separator further comprises a reaction product of an organic carbonate.
11. The electrochemical cell of claim 10 , wherein the organic carbonate is ethylene carbonate.
12. The electrochemical cell of claim 10 , wherein the organic carbonate is propylene carbonate.
13. The electrochemical cell of claim 1 , wherein the separator does not melt at temperatures lower than 300° C.
14. The electrochemical cell of claim 1 , wherein the separator has a tensile strength between about 100 kg/cm 2 to about 500 kg/cm 2 at 2 percent elongation.
15. The electrochemical cell of claim 1 , wherein the separator is nanoporous.
16. The electrochemical cell of claim 1 , wherein an average pore diameter of the separator is from 30 nm to 50 nm.
17. The electrochemical cell of claim 1 , wherein the hydrated aluminum oxide and the organic polymer form a xerogel layer.
18. The electrochemical cell of claim 17 , wherein a thickness of the xerogel layer is from 2 microns to 25 microns.
19. The electrochemical cell of claim 1 , wherein the anode comprises lithium as an anode active material.
20. The electrochemical cell of claim 1 , wherein the cell is a lithium ion secondary cell.