Organic/inorganic composite porous layer-coated electrode and electrochemical device comprising the same

• US 20050266150A1
• Filed: 02/04/2005
• Published: 12/01/2005
• Est. Priority Date: 02/07/2004
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Lee, Sang Young, Ahn, Soon Ho, Kim, Seok Koo, Yong, Hyun Hang
• Granted Patent: US 7,682,740 B2
• Time in Patent Office: Days
• US Class Current: 427/58
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2004/028 Positive electrodes
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 2300/0065 Solid electrolytes
• CPC Class Codes: H01M 2300/0091 in the form of mixtures
• CPC Class Codes: H01M 2300/0094 in the form of layered products, e.g. coatings
• CPC Class Codes: H01M 4/04 Processes of manufacture in general
• CPC Class Codes: H01M 4/0402 Methods of deposition of the material
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0416 involving impregnation with a solution, dispersion, paste or dry powder H01M4/0438 takes precedence
• CPC Class Codes: H01M 4/0435 Rolling or calendering
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/139 Processes of manufacture
• CPC Class Codes: H01M 50/446 Composite material consisting of a mixture of organic and inorganic materials
• CPC Class Codes: H01M 50/46 Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Disclosed is an electrode comprising a first organic/inorganic composite porous coating layer formed on its surface, wherein the first coating layer includes inorganic particles and a binder polymer for interconnecting and fixing the inorganic particles, and has micropores formed by interstitial volumes among the inorganic particles. An electrochemical device including the same electrode is also disclosed. Further, disclosed is a method for manufacturing an electrode having an organic/inorganic composite porous coating layer on the surface thereof, comprising the steps of: (a) coating a current collector with slurry containing an electrode active material and drying it to provide an electrode; and (b) coating the surface of electrode obtained from step (a) with a mixture of inorganic particles with a binder polymer. A lithium secondary battery including the electrode shows improved safety and minimized degradation in battery performance.

Claims

1. An electrode comprising a first organic/inorganic composite porous coating layer formed on its surface, wherein the first coating layer includes inorganic particles and a binder polymer for interconnecting and fixing the inorganic particles, and has micropores formed by interstitial volumes among the inorganic particles.

2. The electrode according to claim 1, which further comprises a second polymeric coating layer formed partially or totally on a surface of electrode active material particles in the electrode.

3. The electrode according to claim 1, wherein the electrode active materials are bonded on a collector while forming a porous structure, and the first organic/inorganic composite porous coating layer and the surface of electrode are anchored to each other.

4. The electrode according to claim 1, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer has a solubility parameter of between 17.0 and 30 [J^1/2/cm^3/2] depending on an electrolyte to be used.

5. The electrode according to claim 1, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer has a dielectric constant (as measured at a frequency of 1 KHz) of between 1 and 100.

6. The electrode according to claim 1, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer is swelled with a liquid electrolyte at a ratio of between 1 and 1,000% based on the weight of the polymer.

7. The electrode according to claim 1, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer is at least one independently selected from the group consisting of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyacrylonitrile-styrene copolymer, polyvinyl chloride (PVC), polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, gelatin, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, polyethylene glycol, glyme, polyethylene glycol dimethylether and carboxymetyl cellulose.

8. The electrode according to claim 2, wherein the second coating layer comprises the polymer in a content of between 0.01 wt % and 50 wt % based on 100 wt % of the electrode active material.

9. The electrode according to claim 2, wherein the polymeric layer forming the second coating layer has a thickness of between 0.001 and 10 μ

m.

10. The electrode according to claim 1, wherein the inorganic particles are at least one selected from the group consisting of:

(a) inorganic particles having a dielectric constant of 10 or more; and

(b) inorganic particles having lithium ion conductivity.

11. The electrode according to claim 10, wherein the inorganic particles having a dielectric constant of 10 or more are at least one selected from the group consisting of BaTiO₃, Pb(Zr,Ti)O₃ (PZT), Pb_1-xLa_xZr_1yTiYO₃ (PLZT), PB(Mg₃Nb_2/3)O₃—

PbTiO₃ (PMN—

PT), hafnia (HfO₂)SrTiO₃, SnO₂, CeO₂, MgO, NiO, CaO, ZnO, ZrO₂, Y₂O₃, Al₂O₃ and TiO₂.

12. The electrode according to claim 10, wherein the inorganic particles having lithium ion conductivity are at least one selected from the group consisting of:

lithim phosphate (Li₃PO₄), lithium titanium phosphate (Li_xTi_y(PO₄)₃, 0<

x<

2, 0<

y<

3), lithium aluminum titanium phosphate (Li_xAl_yTi_z(PO₄)₃, 0<

x<

2, 0<

y<

1, 0<

z<

3), (LiAlTiP)_xO_y type glass (0<

x<

4, 0<

y<

13), lithium lanthanum titanate (Li_xLa_yTiO₃, 0<

x<

2, 0<

y<

3), lithium germanium thiophosphate (Li_xGe_yP_zS_w, 0<

x<

4, 0<

y<

1, 0<

z<

1, 0<

w<

5), lithium nitrides(Li_xN_y, 0<

x<

4, 0<

y<

2), SiS₂ type glass (Li_xSi_yS_z, 0<

x<

3, 0<

y<

2, 0<

z<

4) and P₂S₅ type glass (Li_xP_yS_z, 0<

x<

3, 0<

y<

3, 0<

z<

7) .

13. The electrode according to claim 1, wherein the inorganic particles have a particle diameter of between 0.001 and 10 μ

m.

14. The electrode according to claim 1, wherein the first coating layer has a thickness of between 1 and 100 μ

m.

15. The electrode according to claim 1, wherein the pore size formed in the first coating layer ranges from 0.001 to 10 μ

m.

16. The electrode according to claim 1, wherein the first coating layer has a porosity of between 10 and 95%.

17. The electrode according to claim 1, wherein the inorganic particles and the binder polymer are present in the first coating layer in a mixing ratio of between 10:

90 and 99;

1 on the weight percent basis.

18. The electrode according to claim 1, which comprises an anode active material or a cathode active material bonded to a current collector, wherein the cathode active material is at least one selected from the group consisting of lithium manganese oxides, lithium cobalt oxides, lithium nickel oxides and lithium iron oxides, and the anode active material is at least one selected from the group consisting of lithium metal, lithium alloys, carbon, petroleum coke, activated carbon, graphite and metal oxides.

19. An electrochemical device comprising a cathode, an anode and an electrolyte, wherein either or both of the cathode and anode are the electrodes as defined in claim 1.

20. The electrochemical device according to claim 19, which is a lithium secondary battery.

21. The electrochemical device according to claim 19, which further comprises a microporous polymeric separator.

22. A method for manufacturing an electrode as defined in claim 1, which comprises the steps of:

(a) coating a current collector with slurry containing an electrode active material and drying it to provide an electrode; and

(b) coating a surface of the electrode obtained from step (a) with a mixture of inorganic particles with a binder polymer.

23. The method according to claim 22, which further comprises step (c) of coating the surface of electrode active material in the electrode obtained from step (a) with a polymer that can be swelled and/or solubilized with the electrolyte, between step (a) and step (b).

24. The method according to claim 22, wherein coating steps (b) and (c) are performed by dissolving or dispersing the polymer that can be swelled and/or solubilized with the electrolyte and the mixture of inorganic particles with a binder polymer, respectively, into a solvent to provide a solution, coating the solution, and then removing the solvent from the solution.

25. The electrode according to claim 2, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer has a solubility parameter of between 17.0 and 30 [J^1/2/cm^3/2] depending on an electrolyte to be used.

26. The electrode according to claim 2, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer has a dielectric constant (as measured at a frequency of 1 KHz) of between 1 and 100.

27. The electrode according to claim 2, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer is swelled with a liquid electrolyte at a ratio of between 1 and 1,000% based on the weight of the polymer.

28. The electrode according to claim 2, wherein each of the binder polymer in the first coating layer and the polymer in the second coating layer is at least one independently selected from the group consisting of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyacrylonitrile-styrene copolymer, polyvinyl chloride (PVC), polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, gelatin, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, polyethylene glycol, glyme, polyethylene glycol dimethylether and carboxymetyl cellulose.

29. An electrochemical device comprising a cathode, an anode and an electrolyte, wherein either or both of the cathode and anode are the electrodes as defined in claim 2.

30. The electrochemical device according to claim 29, which is a lithium secondary battery.

31. The electrochemical device according to claim 29, which further comprises a microporous polymeric separator.

32. A method for manufacturing an electrode as defined in claim 2, which comprises the steps of:

(a) coating a current collector with slurry containing an electrode active material and drying it to provide an electrode; and

(b) coating a surface of the electrode obtained from step (a) with a mixture of inorganic particles with a binder polymer.

33. The method according to claim 32, which further comprises step (c) of coating the surface of electrode active material in the electrode obtained from step (a) with a polymer that can be swelled and/or solubilized with the electrolyte, between step (a) and step (b).

34. The method according to claim 32, wherein coating steps (b) and (c) are performed by dissolving or dispersing the polymer that can be swelled and/or solubilized with the electrolyte and the mixture of inorganic particles with a binder polymer, respectively, into a solvent to provide a solution, coating the solution, and then removing the solvent from the solution.

35. The method according to claim 23, wherein coating steps (b) and (c) are performed by dissolving or dispersing the polymer that can be swelled and/or solubilized with the electrolyte and the mixture of inorganic particles with a binder polymer, respectively, into a solvent to provide a solution, coating the solution, and then removing the solvent from the solution.

36. The method according to claim 33, wherein coating steps (b) and (c) are performed by dissolving or dispersing the polymer that can be swelled and/or solubilized with the electrolyte and the mixture of inorganic particles with a binder polymer, respectively, into a solvent to provide a solution, coating the solution, and then removing the solvent from the solution.