Electrode for secondary battery, preparation thereof, and secondary battery and cable-type secondary battery comprising the same
View Patent ↗A sheet-form electrode for a secondary battery includes a current collector; an electrode active material layer formed on one surface of the current collector; a porous organic-inorganic layer formed on the electrode active material layer and including inorganic particles and a polymer binder; and a first porous supporting layer formed on the porous organic-inorganic layer. The sheet-form electrode for a secondary battery has supporting layers on at least one surface thereof to exhibit surprisingly improved flexibility and prevent the release of the electrode active material layer from a current collector even if intense external forces are applied to the electrode, thereby preventing the decrease of battery capacity and improving the cycle life characteristic of the battery.
1. A sheet-form electrode for a secondary battery, comprising:
a current collector;
an electrode active material layer formed on one surface of the current collector;
a porous organic-inorganic layer formed on the electrode active material layer and comprising inorganic particles and a polymer binder;
a first porous supporting layer formed on the porous organic-inorganic layer; and
a second supporting layer formed on another surface of the current collector,
wherein the sheet-form electrode is formed in a substantially helical shape.
2. The electrode for a secondary battery according to claim 1 , wherein the current collector is made of stainless steel, aluminum, nickel, titanium, sintered carbon, or copper; stainless steel treated with carbon, nickel, titanium or silver on a surface thereof; an aluminum-cadmium alloy; a non-conductive polymer treated with a conductive material on a surface thereof; a conductive polymer; a metal paste comprising metal powders of Ni, Al, Au, Ag, Pd/Ag, Cr, Ta, Cu, Ba or ITO; or a carbon paste comprising carbon powders of graphite, carbon black or carbon nanotube.
3. The electrode for a secondary battery according to claim 1 , wherein the current collector is in the form of a mesh.
4. The electrode for a secondary battery according to claim 1 , wherein the current collector further comprises a primer coating layer consisting of a conductive material and a binder.
5. The electrode for a secondary battery according to claim 4 , wherein the conductive material comprises any one selected from the group consisting of carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, graphene and a mixture thereof.
6. The electrode for a secondary battery according to claim 4 , wherein the binder of the primer coating layer is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro propylene, polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, styrene-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, polyimide and a mixture thereof.
7. The electrode for a secondary battery according to claim 1 , wherein the current collector has a plurality of recesses on at least one surface thereof.
8. The electrode for a secondary battery according to claim 7 , wherein the plurality of recesses are continuously patterned or intermittently patterned.
9. The electrode for a secondary battery according to claim 8 , wherein the continuously patterned recesses are formed with spacing apart with each other in a longitudinal direction.
10. The electrode for a secondary battery according to claim 8 , wherein the intermittently patterned recesses are formed by a plurality of holes.
11. The electrode for a secondary battery according to claim 10 , wherein the plurality of holes are a circular or polygonal shape.
12. The electrode for a secondary battery according to claim 1 , wherein the first supporting layer is a mesh-form porous membrane or a non-woven fabric.
13. The electrode for a secondary battery according to claim 1 , wherein the first supporting layer 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, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalate, and a mixture thereof.
14. The electrode for a secondary battery according to claim 1 , wherein the electrode further comprises a conductive material-coating layer having a conductive material and a binder on the first supporting layer.
15. The electrode for a secondary battery according to claim 14 , wherein the conductive material and the binder of the conductive material-coating layer are present in a weight ratio of 80:20 to 99:1 in the conductive material-coating layer.
16. The electrode for a secondary battery according to claim 14 , wherein the conductive material comprises any one selected from the group consisting of carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotube, graphene and a mixture thereof.
17. The electrode for a secondary battery according to claim 14 , wherein the binder of the conductive material-coating layer is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro propylene, polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, styrene-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, polyimide and a mixture thereof.
18. The electrode for a secondary battery according to claim 1 , wherein the porous organic-inorganic layer is formed from a mixture of the inorganic particles and the polymer binder in a weight ratio of 20:80 to 95:5.
19. The electrode for a secondary battery according to claim 1 , wherein the porous organic-inorganic layer has a pore size of 0.01 to 10 μm and a porosity of 5 to 95%.
20. The electrode for a secondary battery 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.
21. The electrode for a secondary battery according to claim 20 , wherein the inorganic particles having a dielectric constant of 5 or higher are selected from the group consisting of BaTiO 3 , Pb(Zr x Ti 1-x )O 3 (PZT, 0<x<1), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT, 0<x<1, 0<y<1), (1−x)Pb(Mg 1/3 Nb 2/3 )O 3 −xPbTiO 3 (PMN-PT, 0<x<1), hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 2 , SiC, SiO 2 , AlOOH, Al(OH) 3 , TiO 2 and a mixture thereof.
22. The electrode for a secondary battery according to claim 20 , wherein the inorganic particles having the ability to transport lithium ions are selected from the group consisting of lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , 0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO 4 ) 3 , 0<x<2, 0<y<1, 0<z<3), (LiAlTiP) x O y type glass (0<x<4, 0<y<13), lithium lanthanum titanate (Li x La y TiO 3 , 0<x<2, 0<y<3), lithium germanium thiophosphate (Li x Ge y P z S w , 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (Li x N y , 0<x<4, 0<y<2), SiS 2 type glass (Li x Si y S z , 0<x<3, 0<y<2, 0<z<4), P 2 S 5 type glass (Li x P y S z , 0<x<3, 0<y<3, 0<z<7) inorganic particles, and a mixture thereof.
23. The electrode for a secondary battery according to claim 1 , wherein the inorganic particles have an average diameter of 10 nm to 5 μm.
24. The electrode for a secondary battery according to claim 1 , wherein the polymer binder is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro propylene, polyvinylidene fluoride-co-trichloroethylene, polybutyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, styrene-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, polyimide and a mixture thereof.
25. The electrode for a secondary battery according to claim 1 , wherein the electrode further comprises a porous coating layer formed on the first porous supporting layer and comprising a mixture of inorganic particles and a binder polymer.
26. The electrode for a secondary battery according to claim 1 , wherein the second supporting layer is a polymer film.
27. The electrode for a secondary battery according to claim 26 , wherein the polymer film is made of any one selected from the group consisting of polyolefin, polyester, polyimide, polyamide and a mixture thereof.
28. The electrode for a secondary battery according to claim 1 , wherein when the electrode for a secondary battery is used as an anode, the electrode active material layer comprises an active material selected from the group consisting of natural graphite, artificial graphite, or carbonaceous material; lithium-titanium complex oxide (LTO), and metals (Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of the metals; an oxide (MeOx) of the metals; a complex of the metals and carbon; and a mixture thereof, and
when the electrode for a secondary battery is used as a cathode, the electrode active material layer comprises an active material selected from the group consisting of LiCoO 2 , LiMn 2 O 4 , LiCoPO 4 , LiFePO 4 , LiNiMnCoO 2 , LiNi 1-x-y-z Co x M1 y M2 z O 2 (wherein M1 and M2 are each independently selected from the group consisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are each independently an atomic fraction of oxide-forming elements, in which 0≦x<0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z≦1), and a mixture thereof.
29. A cable-type secondary battery comprising the electrode according to claim 1 .