ANODE FOR SECONDARY BATTERY HAVING NEGATIVE ACTIVE MATERIAL WITH NANO-FIBER NETWORK STRUCTURE AND SECONDARY BATTERY USING THE SAME, AND FABRICATION METHOD OF NEGATIVE ACTIVE MATERIAL FOR SECONDARY BATTERY

• US 20080274403A1
• Filed: 04/30/2008
• Published: 11/06/2008
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: HONG, Jae-Min, JO, Seong-Mu, KIM, Il-Doo
• Granted Patent: US 8,048,567 B2
• Time in Patent Office: Days
• US Class Current: 429/209
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/3275 Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
• CPC Class Codes: C04B 2235/3277 Co3O4
• CPC Class Codes: C04B 2235/3279 Nickel oxides, nickalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3281 Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/3293 Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
• CPC Class Codes: C04B 2235/441 Alkoxides, e.g. methoxide, tert-butoxide
• CPC Class Codes: C04B 2235/444 Halide containing anions, e.g. bromide, iodate, chlorite
• CPC Class Codes: C04B 2235/449 Organic acids, e.g. EDTA, citrate, acetate, oxalate
• CPC Class Codes: C04B 2235/526 characterised by the length of the fibers
• CPC Class Codes: C04B 2235/5264 characterised by the diameter of the fibers
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 35/62231 based on oxide ceramics
• CPC Class Codes: C04B 35/6225 Fibres based on zirconium oxide, e.g. zirconates such as PZT
• CPC Class Codes: C04B 35/62254 : Fibres based on copper oxide
• CPC Class Codes: C04B 35/62259 : Fibres based on titanium oxide
• CPC Class Codes: C04B 35/624 : Sol-gel processing
• CPC Class Codes: C04B 35/63416 : Polyvinylalcohols [PVA]; Polyvinylacetates
• CPC Class Codes: D01D 5/0007 : Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01F 9/10 : by decomposition of organic substances D01F9/12 takes precedence
• CPC Class Codes: H01M 10/052 : Li-accumulators
• CPC Class Codes: H01M 2004/027 : Negative electrodes
• CPC Class Codes: H01M 4/0435 : Rolling or calendering
• CPC Class Codes: H01M 4/0471 : involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/131 : Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/1391 : of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/661 : Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y10S 977/948 : Energy storage/generating using nanostructure, e.g. fuel cell, battery

Abstract

There is provided a metal oxide having a continuous nano-fiber network structure as a negative active material for a secondary battery. A method for fabricating such negative active material for a secondary battery comprises spinning a mixed solution of a metal oxide precursor and a polymer onto a collector to form composite fibers mixed with the metal oxide precursor and the polymer, thermally compressing or thermally pressurizing the composite fibers, and thermally treating the thermally compressed or thermally pressurized composite fibers to remove the polymer from the composite fiber.

Claims

1. An anode for a secondary battery, comprising:

an anode collector; and

a negative active material compressed on at least one surface of the collector and being a thin porous metal oxide layer with a network structure of nano-fibers composed of at least one of nano-grains, nano-rods, and nano-particles.

2. The anode for a secondary battery of claim 1, wherein an average diameter of the nano-fibers is 10-600 nm, and an average size of the nano-grains, nano-rods, and nano-particles is 5-100 nm.

3. The anode for a secondary battery of claim 1, wherein pores having an average size of 1-100 nm are formed between the nano-grains and between the nano-rods and between the nano-particles.

4. The anode for a secondary battery of claim 1, wherein the collector is formed of (1) a material selected from a group of Pt, Au, Pd, Ir, Ag, Rh, Ru, Ni, stainless steel, Al, Mo, Cr, Cu and W, or (2) ITO (In doped SnO₂) or FTO (F doped SnO₂), or (3) a metallic material formed on an Si wafer.

5. The anode for a secondary battery of claim 1, wherein the metal oxide is one selected from a group of SnO₂, TiO₂, Fe₂O₃, Fe₃O₄, CoO, Co₃O₄, CuO, ZnO, In₂O₃, NiO, MoO₃ and WO₃.

6. A secondary battery, comprising:

an anode having an anode collector and a negative active material compressed on at least one surface of the collector;

an electrolyte; and

a cathode,

wherein the negative active material is a thin porous metal oxide layer with a network structure of nano-fibers composed of at least one of nano-grains, nano-rods, and nano-particles.

7. A fabrication method of a negative active material for a secondary battery, comprising:

spinning a mixed solution of a metal oxide precursor and a polymer onto a collector to form composite fibers mixed with the metal oxide precursor and the polymer;

thermally compressing or thermally pressurizing the composite fibers; and

thermally treating the thermally compressed or thermally pressurized composite fibers to remove the polymer from the composite fibers.

8. The method of claim 7, wherein the metal oxide precursor contains one ion selected from a group of Sn, Ti, Ni, Fe, Co, Cu, Zn, In, Mo and W, and can form an oxide selected from a group of SnO₂, TiO₂, NiO, Fe₂O₃, Fe₃O₄, CoO, Co₃O₄, CuO, ZnO, In₂O₃, MoO₃ and WO₃ through a thermal treatment after being spun while being mixed with the polymer.

9. The method of claim 7, wherein the polymer is at least one selected from a group of polyurethane, polyetherurethane, polyurethane copolymer, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, polymethylmethacrylate (PMMA), polymethylacrylate (PMA), polyacryl copolymer, polyvinylacatate (PVAc), polyvinyl acetate copolymer, polyvinyl alcohol (PVA), polyperfluoroacrylate (PPFA), polystyrene, polystyrene copolymer, polyethylene oxide (PEO), poly(propylene oxide) (PPO), polyethylene oxide copolymer, polypropylene oxide copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polycaprolactone, polyvinylpyrrolidone (PVP), polyvinylfluoride, polyvinylidenfluoride copolymer, and polyamide.

10. The method of claim 7, wherein the spinning is one selected from a group of electrospinning, melt-blowing, flash spinning and electrostatic melt-blowing.

11. The method of claim 7, wherein the thermal compression applies pressure at a temperature higher than a glass transition temperature of the polymer to melt the polymer partially or entirely from the composite fibers.

12. The method of claim 7, wherein the polymer is a polyvinyl acetate (PVAC) and the thermal compression is performed under a pressure of 1.5 Kgf/cm² (21.34 psi) at 120°

C. for 1-10 minutes.

13. The method of claim 7, wherein the thermal pressurization induces melting of the polymer through heating at a temperature higher than the glass transition temperature of the polymer, or induces melting of the polymer by pressurizing using a compressed air having a temperature higher than the glass transition temperature of the polymer.

14. The method of claim 7, wherein the thermal treatment is performed at a temperature of 200-800°

C.