Electrode assembly and lithium secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-9786891-B2
Application number	US-201414436264-A
Country	US
Kind code	B2
Filing date	Oct 31, 2014
Priority date	Oct 31, 2013
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

An electrode assembly, comprises one or more first electrodes comprising a cathode; one or more second electrodes comprising an anode; and a separator sheet having a zigzag form interposed therebetween. The separator sheet comprises a first porous polymer substrate; a first coating layer formed on one surface of the first porous polymer substrate and comprising a polymer binder, the first coating layer being faced with the cathode; and a second coating layer formed on the other surface of the first porous polymer substrate and comprising a mixture a polymer binder and inorganic particles, the second coating layer being faced with the anode and having a composition, a thickness and a porosity different from those of the first porous coating layer. A separator has porous coating layers with a different composition, thickness or porosity formed on each surface thereof.

First claim

What is claimed is:

1. An electrode assembly, comprising:
one or more first electrodes comprising one or more cathodes, one or more anodes, and a separator interposed between the cathodes and the anodes to be laminated alternately so as to separate them;
one or more second electrodes comprising one or more anodes; and
a separator sheet interposed between the first electrodes and the second electrodes to be laminated alternately so as to separate them and having multiple folded portions,
wherein the separator sheet comprises a first porous polymer substrate, a first coating layer formed on one surface of the first porous polymer substrate and comprising a polymer binder, the first coating layer being faced with at least one of the cathodes of the first electrodes, and a second coating layer formed on the other surface of the first porous polymer substrate and comprising a mixture a polymer binder and inorganic particles, the second coating layer being faced with at least one of the anodes of the second electrodes and having a composition, a thickness and a porosity different from those of the first porous coating layer,
wherein the separator comprises a second porous polymer substrate, a third coating layer formed on one surface of the second porous polymer substrate and comprising a polymer binder, the third coating layer being faced with at least one of the cathodes of the first electrodes, and a fourth coating layer formed on the other surface of the second porous polymer substrate and comprising a mixture of a polymer binder and inorganic particles, the fourth coating layer being faced with at least one of the anodes of the first electrodes and having a composition, a thickness and a porosity different from those of the third porous coating layer, and
wherein the thickness ratio of the first porous coating layer and the second porous coating layer ranges from 1:9 to 4:6, and the thickness ratio of the third porous coating layer and the fourth porous coating layer ranges from 1:9 to 4:6.

2. The electrode assembly according to claim 1 , wherein the multiple folded portions in the separator sheet is obtained by folding in a zigzag form, and the electrode assembly has a zigzag-folded structure.

3. The electrode assembly according to claim 1 , wherein the first porous coating layer has a porosity of 20 to 50%, and the second porous coating layer has a porosity of 30 to 60%.

4. The electrode assembly according to claim 1 , wherein the first porous coating layer further comprises inorganic particles.

5. The electrode assembly according to claim 1 , wherein the inorganic particles are inorganic particles having a dielectric constant of 5 or higher, inorganic particles having the ability to transport lithium ions, or a mixture thereof.

6. The electrode assembly according to claim 5 , wherein the inorganic particles having a dielectric constant of 5 or higher are any one selected from the group consisting of BaTiO3, Pb(ZrxTi1−x)O3 (PZT, 0<x<1), Pb1−xLaxZr1−yTiyO3 (PLZT, 0<x<1, 0<y<1), (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMN-PT, 0<x<1), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, SiC, TiO2, SiO2, AlOOH, Al(OH)3, and a mixture thereof.

7. The electrode assembly according to claim 5 , wherein the inorganic particles having the ability to transport lithium ions are any one selected from the group consisting of lithium phosphate (Li3PO4), lithium titanium phosphate (LixTiy(PO4)3, 0<x<2, 0<y<3), lithium aluminum titanium phosphate (LixAlyTiz(PO4)3, 0<x<2, 0<y<1, 0<z<3), (LiAlTiP)xOy type glass (0<x<4, 0<y<13), lithium lanthanum titanate (LixLayTiO3, 0<x<2, 0<y<3), lithium germanium thiophosphate (LixGeyPzSw, 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (LixNy, 0<x<4, 0<y<2), SiS2 type glass (LixSiySz, 0<x<3, 0<y<2, 0<z<4), P2S5 type glass (LixPySz, 0<x<3, 0<y<3, 0<z<7), and a mixture thereof.

8. The electrode assembly according to claim 1 , wherein the polymer binder is selected from the group consisting of polyvinylidene fluoride (PVDF), hexafluoro propylene (HFP), polyvinylidene fluoride-co-hexafluoro propylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, and a mixture thereof.

9. The electrode assembly according to claim 1 , wherein the first porous polymer substrate is a polyolefin-based membrane or non-woven fabric.

10. The electrode assembly according to claim 1 , wherein the first porous polymer substrate is made of any one selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polybutylene, polypentene, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalate, and a mixture thereof.

11. The electrode assembly according to claim 1 , wherein the first porous polymer substrate is formed in a single layer, or in a lamination of two or more layers.

12. The electrode assembly according to claim 1 , wherein at least one of the cathodes has a cathode active material comprising a lithium-containing oxide.

13. The electrode assembly according to claim 12 , wherein the lithium-containing oxide is a lithium-containing transition metal oxide.

14. The electrode assembly according to claim 13 , wherein the lithium-containing transition metal oxide is any one selected from the group consisting of LixCoO2 (0.5<x<1.3), LixNiO2 (0.5<x<1.3), LixMnO2 (0.5<x<1.3), LixMn2O4 (0.5<x<1.3), Lix(NiaCobMnc)O2 (0.5<x<1.3, 0<a<1, 0<b<1, 0<c<1, a+b+c=1), LixNi1−yCoyO2 (0.5<x<1.3, 0<y<1), LixCo1−yMnyO2 (0.5<x<1.3, 0<y<1), LixNi1−yMnyO2 (0.5<x<1.3, 0<y<1), Lix(NiaCobMnc)O4 (0.5<x<1.3, 0<a<2, 0<b<2, 0<c<2, a+b+c=2), LixMn2−zNizO4 (0.5<x<1.3, 0<z<2), LixMn2−zCozO4 (0.5<x<1.3, 0<z<2), LixCoPO4 (0.5<x<1.3), LixFePO4 (0.5<x<1.3), and a mixture thereof.

15. The electrode assembly according to claim 1 , wherein the at least one of the anodes has an anode active material comprising metallic lithium, a carbon-based material, a metal compound or a mixture thereof.

16. The electrode assembly according to claim 15 , wherein the metal compound is a compound containing at least one metal selected from Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Mg, Sr, Ba, and a mixture thereof.

17. The electrode assembly according to claim 1 , wherein the first electrodes consist of a single layer of cathode.

18. The electrode assembly according to claim 1 , wherein the second electrodes consist of a single layer of anode.

19. The electrode assembly according to claim 1 , wherein the third porous coating layer has a porosity of 20 to 50%, and the fourth porous coating layer has a porosity of 30 to 60%.

20. The electrode assembly according to claim 1 , wherein the first porous coating layer and the third porous coating layer have the same composition, thickness and porosity, and the second porous coating layer and the fourth porous coating layer have the same composition, thickness and porosity.

21. The electrode assembly according to claim 1 , wher

Assignees

• Lg Chemical Ltd

Inventors

• Choi Jung-Seok
• Oh Song-Taek
• Lee Su-Rim
• Lee Hyeok-Moo
• Park Ji-Hye

Classifications

• H01M4/622 Primary

  being polymers · CPC title

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/466

  U-shaped, bag-shaped or folded · CPC title

• H01M50/454

  comprising a non-fibrous layer and a fibrous layer superimposed on one another · CPC title