JPH10112321A - Nonaqueous electrolyte secondary battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery with low cycle deterioration rate and high reliability. SOLUTION: In a nonaqueous electrolyte secondary battery in which a negative electrode 1 and a positive electrode 2 are oppositely arranged through a separator 3 and they are sealed in a battery can 5 through a sealing gasket 6, an active material layer having an active material holding binder is formed in at least either one of a negative current collector 10 and a positive current collector 11, and the active material holding binder is crosslinked by irradiating electron beams. The active material layer is formed on the surface of either one of the negative current collector 10 and the positive current collector 11, and electron beams of 10kGy or more but 700kGy or less are irradiated to the active material layer crosslinking the active material holding binder in the active material layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery and a method for producing the same, and more particularly, to a negative electrode and a positive electrode which are opposed to each other with a separator therebetween, and sealed in a battery can with a sealing gasket. The present invention relates to a non-aqueous electrolyte secondary battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the development of cordless electronic devices such as electronic notebooks, computers, portable telephones and the like has been remarkable. For these power supplies, battery voltage is high, high energy density is high, and A non-aqueous electrolyte secondary battery with less self-discharge and excellent cycle characteristics is expected. By the way, in a nonaqueous electrolyte secondary battery in which a negative electrode is made of an active material capable of doping and undoping lithium and a positive electrode is made of a lithium transition metal oxide, an active material layer formed on each current collector surface Contains an active material holding binder such as polyvinylidene fluoride or polytetrafluoroethylene.

[0003] However, the conventional binder for holding active material is not three-dimensionally stitch-crosslinked, so that it swells and deteriorates due to the electrolyte especially at high temperatures, and as a result, the charge / discharge of the nonaqueous electrolyte secondary battery is repeated. After that, the rate of deterioration of the discharge capacity with respect to the initial discharge amount, that is, the so-called cycle deterioration rate becomes large, which is one factor that impairs reliability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery having a low cycle deterioration rate and high reliability.

[0005]

In order to solve the above-mentioned problems, in a non-aqueous electrolyte secondary battery according to the present invention, a negative electrode and a positive electrode are arranged to face each other with a separator interposed therebetween and a sealing gasket is inserted in a battery can. In a non-aqueous electrolyte secondary battery which is hermetically sealed, at least either the negative electrode or the positive electrode current collector contains a copolymer containing 90% by weight or more of vinylidene fluoride, or a hexagon containing 30% by weight or more of vinylidene fluoride. A copolymer of fluoropropylene and vinylidene fluoride, or a copolymer of hexafluoropropylene and 35% by weight or more of vinylidene fluoride, or a copolymer of hexafluoropropylene and vinylidene fluoride and tetrafluoroethylene; Alternatively, a copolymer of hexafluoropropylene and vinylidene fluoride and vinylidene fluoride in an amount of 90% by weight or less. An active material layer having an active material holding binder containing a copolymer is formed, and these active material holding binders are cross-linked by irradiation with an electron beam. .

In the method of manufacturing a non-aqueous electrolyte secondary battery according to the present invention, the negative electrode and the positive electrode are arranged to face each other with a separator interposed therebetween, and the non-aqueous electrolyte is sealed in a battery can with a sealing gasket. In a method for producing a secondary battery, a copolymer containing at least one collector of at least one of a negative electrode and a positive electrode containing 90% by weight or more of vinylidene fluoride, or 30% by weight or more of hexafluoropropylene and vinylidene fluoride Or a copolymer of hexafluoropropylene and vinylidene fluoride in an amount of 35% by weight or more, or a copolymer of hexafluoropropylene and vinylidene fluoride and tetrafluoroethylene, or hexafluoropropylene and vinylidene Copolymer containing 90% by weight or more of vinylidene fluoride and copolymer with fluoride Forming an active material layer having an active material-holding binder containing, and irradiating the active material layer with an electron beam having an irradiation amount of 10 kGy or more and 700 kGy or less to crosslink the above-mentioned active material holding binder. And a step of performing

According to the above-mentioned means, the active material holding binder contained in the active material layer can be easily crosslinked by irradiation with an electron beam, and the crosslink density can be easily controlled by the irradiation amount. Can be. In addition, the crosslinked active material holding binder has improved heat resistance and chemical resistance,
This has the effect of suppressing swelling and deterioration due to the electrolyte, and also suppressing the cycle deterioration rate of the nonaqueous electrolyte secondary battery.

[0008]

EXAMPLES Hereinafter, specific examples to which the present invention is applied,
A comparative example in comparison with the embodiment will be described with reference to a schematic side sectional view of the cylindrical nonaqueous electrolyte secondary battery shown in FIG. It goes without saying that the present invention is not limited to the embodiments described below.

Example 1 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 30/70 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both sides of a 10 μm thick aluminum foil serving as a negative electrode current collector 10 after drying. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 30/70 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Next, between the obtained positive electrode 2 and negative electrode 1,
Wrapped several times with the separator 3 made of a polyethylene resin film having a thickness of 25 μm interposed therebetween, and an outer diameter of 18 mm
Was prepared and stored in a nickel-plated battery can 5. Then, after arranging the insulating plates 4 above and below the spiral electrode body, the positive electrode lead 13 is led out from the current collector of the positive electrode 2 and welded to the battery lid 7, and the negative electrode lead 12 is drawn out from the current collector of the negative electrode 1. And welded to the battery can 5.

Next, LiPF ₆ is added to a mixed solvent obtained by mixing propylene carbonate and dimethyl carbonate at a volume ratio of 1: 1 in the battery can 5 containing the spiral electrode body.
After the injection of an electrolytic solution in which 1 mol / l is dissolved, a safety valve device 8 having a current cutoff mechanism and a battery lid 7 are caulked and fixed to the battery can 5 via a sealing gasket 6 coated on the surface with asphalt, and the outer diameter is adjusted. A cylindrical non-aqueous electrolyte secondary battery having a height of 18 mm and a height of 65 mm was completed.

Example 2 First, the following composition was mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 10 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layers formed on both surfaces was irradiated with an electron beam of 10 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 3 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 100 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both sides of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 100 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 4 First, the following composition was mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed in the same steps as in the case shown in Example 1.

Example 5 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 700 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layers formed on both surfaces was irradiated with an electron beam of 700 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 6 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area: 0.4 m ² / g) 85 parts by weight Carbon (specific surface area: 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 60/40 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both sides of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 60/40 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 7 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area: 0.4 m ² / g) 85 parts by weight Carbon (specific surface area: 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 30/45/25 Polymer 5 parts by weight N-methyl-2-pyrrolidone 40 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 30/45/25 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 8 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was used as a positive electrode current collector 11
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area: 0.4 m ² / g) 85 parts by weight Carbon (specific surface area: 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 35/35/35 Polymer 5 parts by weight N-methyl-2-pyrrolidone 40 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

85 parts by weight of carbon (specific surface area: 8 m ² / g) 15 parts by weight of copolymer of hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 35/35/35 15 parts by weight of N-methyl-2-pyrrolidone (Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 9 First, the following composition was mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 1.5 parts by weight 5 parts by weight of polyvinylidene fluoride (polyvinylidene fluoride) 40 parts by weight of N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both sides of a 10 μm-thick aluminum foil serving as a negative electrode current collector and dried. It is applied to a thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area: 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 4.5 parts by weight Polyvinylidene fluoride (polyvinylidene fluoride) 10.5 parts by weight N -Methyl-2-pyrrolidone 50 parts by weight (Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Example 10 First, the following compositions were mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 500 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Polyvinylidene fluoride 5 parts by weight (polyvinylidene fluoride) N-methyl-2-pyrrolidone 40 Weight part (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both sides of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 after drying. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layers formed on both surfaces was irradiated with an electron beam of 500 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Polyvinylidene fluoride 15 parts by weight (polyvinylidene fluoride) N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed in the same steps as in the case shown in Example 1.

Comparative Example 1 In this comparative example, neither a copper foil having a positive electrode active material layer formed on both surfaces nor an aluminum foil having a negative electrode active material layer formed on both surfaces was irradiated with an electron beam. First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was dried on both surfaces of a 20 μm thick copper foil serving as the positive electrode current collector 11 to have a positive electrode active material layer thickness of 100 μm. And dried. Then, it was pressed and cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Polyvinylidene fluoride 5 parts by weight (polyvinylidene fluoride) N-methyl-2-pyrrolidone 40 Weight part (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer coating material, which was dried on both surfaces of a 10 μm-thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. Then, it was pressed and cut into the size of the negative electrode 1.

Carbon (specific surface area: 8 m ² / g) 85 parts by weight Polyvinylidene fluoride 15 parts by weight (polyvinylidene fluoride) N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Comparative Example 2 First, the following composition was mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 25/75 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both sides of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and then dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 25/75 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Comparative Example 3 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer paint, which was dried on both sides of a 20 μm thick copper foil serving as the positive electrode current collector 11 and dried. It is applied so that the thickness of the active material layer becomes 100 μm, and dried. The copper foil with the positive electrode active material layer formed on both sides
It was irradiated with an electron beam of 0 kGy and then pressed to cut into a size of the positive electrode 2.

LiCoO ₂ (specific surface area: 0.4 m ² / g) 85 parts by weight Carbon (specific surface area: 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 35/30/35 Polymer 5 parts by weight N-methyl-2-pyrrolidone 40 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 after drying. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 300 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride / tetrafluoroethylene = 35/30/35 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Comparative Example 4 First, the following composition was mixed in a ball mill for 5 hours to prepare a coating for a positive electrode active material layer.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 5 kGy, and then pressed to cut into a size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 5 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area: 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

Comparative Example 5 First, the following composition was mixed in a ball mill for 5 hours to prepare a positive electrode active material layer coating material.
The thickness of the positive electrode active material layer after drying on both sides of a 0 μm thick copper foil is 10
It is applied to a thickness of 0 μm and dried. The copper foil having the positive electrode active material layer formed on both surfaces was irradiated with an electron beam of 800 kGy, and then pressed to cut into a size of the positive electrode 2.

LiCoO ₂ (specific surface area 0.4 m ² / g) 85 parts by weight Carbon (specific surface area 250 m ² / g) 10 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 5 parts by weight N- Methyl-2-pyrrolidone 40 parts by weight (Mitsubishi Chemical Corporation)

Next, the following composition was mixed in a ball mill for 5 hours to prepare a negative electrode active material layer paint, which was dried on both surfaces of a 10 μm thick aluminum foil serving as the negative electrode current collector 10 and dried. It is applied so as to have a layer thickness of 100 μm and dried. The aluminum foil having the negative electrode active material layer formed on both surfaces was irradiated with an electron beam of 800 kGy, and then pressed to cut into the size of the negative electrode 1.

Carbon (specific surface area 8 m ² / g) 85 parts by weight Hexafluoropropylene / vinylidene fluoride = 40/60 copolymer 15 parts by weight N-methyl-2-pyrrolidone 50 parts by weight (manufactured by Mitsubishi Chemical Corporation)

Thereafter, a cylindrical non-aqueous electrolyte secondary battery having an outer diameter of 18 mm and a height of 65 mm was completed by the same steps as in the case shown in Example 1.

As described above, Examples 1 to 10 and Comparative Examples 1 to 5
Was evaluated under the following conditions for the cycle deterioration rate, and the results are shown in Table 1 for Examples to which the present invention was applied, and Table 2 for Comparative Examples in comparison with the Examples.

Cycle Degradation Rate The completed non-aqueous electrolyte secondary battery was
A, after performing 4.2V constant-current constant-voltage charging for 3 hours,
A performed constant current discharge at a cutoff of 2.75 V, which was defined as the initial discharge capacity. Next, the discharge capacity after 100 cycles of charging under the same atmosphere and charging conditions as above was defined as the post-cycle capacity. Then, the ratio of (initial capacity-capacity after cycle) / initial capacity was expressed in% and evaluated.

[0087]

[Table 1]

[0088]

[Table 2]

As is clear from Table 1, all of the examples 1 to 10 to which the present invention is applied have a cycle deterioration rate of 17%.
% Or less, and a non-aqueous electrolyte secondary battery having high reliability could be obtained. However, in Comparative Examples 1 to 5 shown in Table 2, the cycle deterioration rate was 27% or more, or As described above, it did not dissolve in both the positive electrode active material layer paint and the negative electrode active material layer paint, and the reliability was insufficient.

[0090]

According to the non-aqueous electrolyte secondary battery of the present invention,
A non-aqueous electrolyte secondary battery having a low cycle deterioration rate and high reliability and a method for manufacturing the same can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of a cylindrical nonaqueous electrolyte secondary battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Negative electrode, 2 ... Positive electrode, 3 ... Separator, 4 ... Insulating plate, 5
... battery can, 6 ... sealing gasket, 7 ... battery lid, 8 ... safety valve device, 9 ... PTC element, 10 ... negative electrode current collector, 11 ... positive electrode current collector, 12 ... negative electrode lead, 13 ... positive electrode lead, 14
… Center pin

Claims (8)

[Claims] A nonaqueous electrolyte secondary battery in which a negative electrode and a positive electrode are opposed to each other with a separator interposed therebetween, and sealed in a battery can via a sealing gasket, wherein at least one of the negative electrode and the positive electrode is provided. An active material layer having an active material holding binder is formed on the current collector, and the active material holding binder is cross-linked by irradiation with an electron beam. Rechargeable battery. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the binder for holding the active material is a copolymer containing 90% by weight or more of vinylidene fluoride. 3. The binder for retaining an active material contains a copolymer of hexafluoropropylene and vinylidene fluoride, and the content of the hexafluoropropylene is 30% by weight or more. The non-aqueous electrolyte secondary battery according to claim 1, wherein: 4. The binder for retaining an active material contains hexafluoropropylene and a copolymer of vinylidene fluoride, and the content of vinylidene fluoride is 35% by weight or more. The non-aqueous electrolyte secondary battery according to claim 1, wherein: 5. The non-woven fabric according to claim 1, wherein the binder for retaining an active material contains a copolymer of hexafluoropropylene and vinylidene fluoride, and tetrafluoroethylene. Water electrolyte secondary battery. 6. The binder for retaining an active material contains a copolymer of hexafluoropropylene and vinylidene fluoride, and a copolymer containing vinylidene fluoride in an amount of 90% by weight or more. Claim 1 characterized by the following:
3. The non-aqueous electrolyte secondary battery according to 1. 7. A method for manufacturing a non-aqueous electrolyte secondary battery in which a negative electrode and a positive electrode are disposed to face each other with a separator therebetween and sealed in a battery can via a sealing gasket, wherein at least one of the negative electrode and the positive electrode is provided. A step of forming an active material layer having an active material holding binder on one of the current collectors, and a step of irradiating the active material layer with an electron beam to crosslink the active material holding binder. A method for producing a non-aqueous electrolyte secondary battery, comprising: 8. The irradiation amount of the electron beam is 10 kGy or more and 7.
The method for producing a non-aqueous electrolyte secondary battery according to claim 7, wherein the secondary battery is at most 00 kGy.