Separators for electrochemical cells
View Patent ↗Provided are separators for use in batteries and capacitors comprising (a) at least 50% by weight of an aluminum oxide and (b) an organic polymer, wherein the aluminum oxide is surface modified by treatment with an organic acid to form a modified aluminum oxide, and wherein the treatment provides dispersibility of the aluminum oxide in aprotic solvents such as N-methyl pyrrolidone. Preferably, the organic acid is a sulfonic acid, such as p-toluenesulfonic acid. Also preferably, the organic polymer is a fluorinated polymer, such as polyvinylidene fluoride. Also provided are electrochemical cells and capacitors comprising such separators.
1. A separator for an electric current producing cell comprising a microporous layer, the microporous layer comprising:
(a) a sulfonic acid-surface-modified hydrated aluminum oxide; and
(b) an organic polymer that is soluble in aprotic solvents.
2. The separator of claim 1 , wherein the sulfonic acid-surface-modified hydrated aluminum oxide has dispersibility in aprotic solvents.
3. The separator of claim 1 , wherein the thickness of the separator is from 5 microns to 20 microns.
4. The separator of claim 1 , wherein the separator is flame retardant and does not melt at temperatures lower than 300° C.
5. The separator of claim 1 , wherein the organic polymer is a fluorinated organic polymer.
6. The separator of claim 1 , wherein the microporous layer is a xerogel layer, and wherein the xerogel layer is a continuous xerogel layer and has a porosity of at least 30%.
7. The separator of claim 1 , wherein the sulfonic acid is an aryl sulfonic acid.
8. The separator of claim 1 , wherein the modified hydrated aluminum oxide comprises a hydrated aluminum oxide of the formula Al 2 O 3 .xH 2 O, wherein x is in the range of 1.0 to 1.5.
9. The separator of claim 1 , wherein the modified hydrated aluminum oxide has an Al 2 O 3 content of 50% to 85% by weight.
10. The separator of claim 1 , wherein the separator comprises 50% to 85% by weight of the modified hydrated aluminum oxide.
11. The separator of claim 1 , wherein the microporous layer has an average pore diameter from 2 nm to 70 nm.
12. An electrochemical cell comprising:
an anode,
a cathode,
an organic electrolyte comprising a lithium salt, and
a separator interposed between the anode and the cathode, wherein the separator comprises a microporous layer, the microporous layer comprising:
(a) a sulfonic acid-surface-modified hydrated aluminum oxide; and
(b) an organic polymer that is soluble in aprotic solvents.
13. The electrochemical cell of claim 12 , wherein the sulfonic acid-surface-modified hydrated aluminum oxide has dispersibility in aprotic solvents.
14. The electrochemical cell of claim 12 , wherein the thickness of the separator is from 5 microns to 20 microns.
15. The electrochemical cell of claim 12 , wherein the separator is flame retardant and does not melt at temperatures lower than 300° C.
16. The electrochemical cell of claim 12 , wherein the organic polymer is a fluorinated organic polymer.
17. The electrochemical cell of claim 12 , wherein the microporous layer is a xerogel layer, and wherein the xerogel layer is a continuous xerogel layer and has a porosity of at least 30%.
18. The electrochemical cell of claim 12 , wherein the sulfonic acid is an aryl sulfonic acid.
19. The electrochemical cell of claim 12 , wherein the modified hydrated aluminum oxide comprises a hydrated aluminum oxide of the formula Al 2 O 3 .xH 2 O, wherein x is in the range of 1.0 to 1.5.
20. The electrochemical cell of claim 12 , wherein the modified hydrated aluminum oxide has an Al 2 O 3 content of 50% to 85% by weight.
21. The electrochemical cell of claim 12 , wherein the separator comprises 50% to 85% by weight of the modified hydrated aluminum oxide.
22. The electrochemical cell of claim 12 , wherein the microporous layer has an average pore diameter from 2 nm to 70 nm.