Batteries having inorganic/organic porous films
View Patent ↗An electrochemical cell, such as Li-Ion, having (a) a positive electrode; (b) a negative electrode, (c) a porous inorganic/organic composite layer interposed between the positive electrode and the negative electrode, and (d) an electrolyte comprising a lithium salt and a non-aqueous solvent. The composite layer includes inorganic nanoparticles and a binder to form a nanocomposite separator (NCS). In addition to the composite layer, the electrochemical cell includes a porous separator.
1. A Li-Ion electrochemical cell comprising
(a) a positive electrode layer comprising a positive electrode binder;
(b) a negative electrode layer comprising a negative electrode binder,
(c) a porous inorganic and organic composite layer comprising inorganic particles and a composite layer binder interposed between the positive electrode and the negative electrode layers and adjacent to one of the positive and negative electrode layers,
(d) an electrolyte comprising a lithium salt and a non-aqueous solvent,
(e) a porous separator adjacent the composite layer, and
(f) a solvent weld at the interface between the composite layer and the adjacent electrode layer, the weld comprising a mixture of the composite layer binder and the electrode binder;
wherein the combined thickness of the composite layer and the porous separator is not greater than 25 μm.
2. The electrochemical cell of claim 1 , wherein the film is a composite layer comprises electrochemically stable inorganic particles having a particle size less than 1 μm in an electrochemically stable binder matrix, and the composite layer has at least a bimodal pore distribution, wherein the first, smaller sized pores are substantially uniformly distributed in the layer, and one or more larger pore sizes are randomly distributed in the layer, wherein the dimension of the pores are nanoscale.
3. The electrochemical cell of claim 1 , wherein the porous separator is a microporous polyolefin separator comprising pores greater than 50 Å in diameter and comprises film of at least one of polypropylene and polyethylene.
4. The electrochemical cell of claim 1 , wherein the porous separator is a non-woven textile material made from fibers.
5. The electrochemical cell of claim 4 , wherein the fibers are held together by at least one of friction, cohesion, and adhesion.
6. The electrochemical cell of claim 1 , wherein the porous separator has a thickness in the range of about 9 μm to 15 μm.
7. The electrochemical cell of claim 1 , wherein the composite layer has a thickness in the range of about 2 μm to 16 μm.
8. The electrochemical cell of claim 2 , wherein first smaller pore size is in the range of about 5-100 nm.
9. The electrochemical cell of claim 2 , wherein larger pore size is in the range of about 100-500 nm.
10. The electrochemical cell of claim 2 , wherein the particles are substantially monodisperse and have a particle size in the range of about 10-50 nm.
11. The electrochemical cell of claim 1 , wherein the composite layer has a pore volume fraction of greater than 25%.
12. The electrochemical cell of claim 1 , wherein the composite layer comprises inorganic particles and polymer binder in a weight ratio of about 95:5 to about 40:60 inorganic particles: binder.
13. The electrochemical cell of claim 1 , wherein the inorganic portion of the composite layer is selected from the group consisting of silica, alumina, titanium oxide, natural and synthetic zeolites.
14. An electrode/separator assembly for use in an electrochemical cell, comprising:
a current collector;
an electrode layer adhered to the current collector, the electrode layer comprising at least electroactive particles and a binder; and
a porous composite layer disposed on the electrode layer comprising inorganic particles substantially uniformly distributed in a binder matrix to form nanopores;
a solvent weld at the interface between the composite layer and the electrode layer on which it is disposed, the weld comprising a mixture of the composite layer matrix binder and the electrode binder; and
a porous separator disposed adjacent the composite layer on a side opposite that of the electrode layer, wherein the combined thickness of the composite layer and the porous separator is not greater than 25 μm.
15. The electrode/separator assembly of claim 14 , wherein the separator comprises a layer of polyethylene oxide.
16. The electrode/separator assembly of claim 14 , wherein the inorganic particles have a particle size less than 1 μm in the binder matrix, the layer having at least a bimodal pore distribution, wherein the first, smaller sized pores are substantially uniformly distributed in the layer, and one or more larger pore sizes are randomly distributed in the layer, wherein the dimension of the pores are nanoscale.
17. The electrode/separator assembly of claim 14 , wherein the porous separator is a microporous polyolefin separator comprising pores greater than 50 Å in diameter and comprises film of at least one of polypropylene and polyethylene.
18. The electrode/separator assembly of claim 14 , wherein the porous separator is a non-woven textile material made from fibers.
19. The electrode/separator assembly of claim 18 , wherein the fibers are held together by at least one of friction, cohesion, and adhesion.
20. The electrode/separator assembly of claim 14 , wherein the porous separator has a thickness in the range of about 9 μm to 15 μm.
21. The electrode/separator assembly of claim 14 , wherein the composite layer has a thickness in the range of about 2 μm to 16 μm.
22. The electrode/separator assembly of claim 16 , wherein first smaller pore size is in the range of about 5-100 nm.
23. The electrode/separator assembly of claim 16 , wherein larger pore size is in the range of about 100-500 nm.
24. The electrode/separator assembly of claim 14 , wherein the inorganic particles are substantially monodisperse and have a particle size in the range of about 10-50 nm.
25. The electrode/separator assembly of claim 14 , wherein the composite layer has a pore volume fraction of greater than 25%.
26. The electrode/separator assembly of claim 14 , wherein the composite layer comprises inorganic particles and polymer binder in a weight ratio of about 95:5 to about 40:60 inorganic particles: binder.
27. The electrode/separator assembly of claim 14 , wherein the inorganic portion of the composite layer is selected from the group consisting of silica, alumina, titanium oxide, natural and synthetic zeolites.
28. The electrochemical cell of claim 1 , wherein the separator comprises a layer of polyethylene oxide.
29. The electrochemical cell of claim 1 , wherein the composite layer binder is in the range of 35-55 wt %.
30. The electrochemical cell of claim 29 , wherein the solvent does not penetrate more than 90% of the thickness of the positive or negative electrode layer.
31. The electrode/separator assembly of claim 14 , wherein the composite layer binder is in the range of 35-55 wt %.
32. The electrochemical cell of claim 31 , wherein the solvent does not penetrate more than 90% of the thickness of the positive or negative electrode layer.