JP2003303624A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the separator from being broken by the protrusion part formed at the top end of the mixture layer, even when the internal pressure is increased by temperature rise or the like in the battery case, and prevent occurrence of internal short circuit due to conduction of the positive electrode and the negative electrode adjoining through the protrusion part. <P>SOLUTION: This is a non-aqueous electrolyte secondary battery that comprises a wound electrode body 12 that is wound in spiral form by interposing a separator 17, 18 between a positive electrode 15 and a negative electrode 16 of belt-shape formed with a mixture layer on the belt-shape current collector and a battery case in which this wound electrode body 12 is housed. The top end in the winding direction of the separator 17, 18 is folded up on the top end in the winding direction of the mixture layer 15a, 15b or 16a, 16b of the positive electrode 15 or the negative electrode 16 and overlapped with the top end of the separator or top end of the adjoining separator, and the separator 17 or 18 is made two-ply to cover the top end of the mixture layer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte in which a spirally wound electrode body formed by spirally winding a strip-shaped positive electrode and a strip-shaped negative electrode via a separator is housed in a battery can. More specifically, the present invention relates to a secondary battery. A non-aqueous electrolyte that can protect an electrode mixture application end of an electrode at an end in a winding direction of a wound electrode body and prevent or suppress the occurrence of an internal short circuit. It relates to the next battery.

[0002]

2. Description of the Related Art As a conventional wound electrode body 1 of this type of non-aqueous electrolyte secondary battery, for example, those shown in FIGS. 11 and 12 are known. 11 and 12, reference numeral 2 is a strip-shaped negative electrode, and reference numeral 3
Is a positive electrode also formed in a strip shape. A strip-shaped separator 4 is arranged on one surface of the negative electrode 2, and a positive electrode 3 is arranged on the opposite side of the separator 4 from the negative electrode 2.
On the other surface, the separator 5 which is also formed in a strip shape is arranged. Thus, the spirally wound electrode body 1 is formed as a whole by appropriately winding the stacked body of four layers.

As shown in FIG. 13, the negative electrode 2 is composed of a strip-shaped negative electrode current collector 2a and negative electrode material mixture layers 2b and 2c coated on both surfaces of the negative electrode current collector 2a. There is. Further, the positive electrode 3 is composed of a positive electrode current collector 3a similarly formed in a strip shape, and positive electrode mixture layers 3b and 3c applied to both surfaces of the positive electrode current collector 3a. Then, the negative electrode 2 and the positive electrode 3 are formed by the separator 4 or 5 interposed between the negative electrode mixture layer 2b or 2c and the positive electrode mixture layer 3c or 3b.
To prevent short circuit due to contact of both poles.

[0004]

However, in such a conventional non-aqueous electrolyte secondary battery as described above, the mixture layer 2b, 2c or 3 is used for both the negative electrode 2 and the positive electrode 3.
The protrusions 6a or 6b as illustrated in FIG.
In addition, a land-shaped partial ridge portion (not shown) was generated. The mixture layer 2b having such ridges 6a and 6b,
2c or 3b, 3c becomes hard with the lapse of time after molding, and the ridges 6a, 6b etc. are left as they are.

Therefore, in the secondary battery manufactured by housing the spirally wound electrode body 1 in a battery can, the pressure in the battery can rises due to, for example, heat generation from the mixture layers 2b, 2c or 3b, 3c. Then, the protrusions 6a and 6b are separated by the separator 4
Or, it is pressed firmly against 5. As a result, the protrusion 6
The a and 6b break through the contact portions 7 of the separators 4 and 5 and project toward the adjacent electrodes. As a result, the ridges 6a, 6b, etc. pierce the separators 4, 5 and project toward the adjacent electrodes, and when the tips of the ridges 6a, 6b contact the mixture layer of the adjacent electrodes, the negative electrode 2 and the positive electrode 3 are separated. There is a problem in that electrical continuity causes an internal short circuit.

The above-mentioned problems will be described in detail below. 9 and 10 show the negative electrode 2
The method for manufacturing the positive electrode 3 and the positive electrode 3 will be described. The negative electrode 2 and the positive electrode 3 are generally manufactured as follows. still,
The negative electrode 2 and the positive electrode 3 are different from each other in the materials used for the current collector and the mixture, but the manufacturing method is the same, and therefore, the manufacturing method of the positive electrode 3 will be described here.

First, a current collector plate 8 having a predetermined size (length M × width B) is prepared, and a positive electrode mixture is applied to both sides of the current collector plate 8 to form mixture layers 3b and 3c. . In this case, first, the positive electrode mixture is applied to one surface of the current collector plate 8 by moving the coating nozzle as shown by the arrow F1 or by moving the current collector plate 8 to form one mixture layer 3b. To do. Next, the current collector plate 7 is turned over and the positive electrode mixture is applied to the other surface by moving the coating nozzle in the same direction as the arrow F1 as shown by the arrow F2 or by moving the current collector plate 8, and the other side. To form the mixture layer 3c. As a result, a positive electrode original plate 9 is manufactured in which a large number of positive electrodes 3 having a length M and a width B are integrally combined.

Next, the positive electrode original plate 9 is cut into a large number of strips each having a predetermined width b as the width of the positive electrode 3. The length M of the positive electrode original plate 9 is a predetermined length, and one end in the length direction is the starting end in the winding direction, and the other end is the ending end in the winding direction. By cutting the positive electrode original plate 9 in the width direction, a large number of positive electrodes 3 having a predetermined size and having a length M and a width b are manufactured.

In this way, the positive electrode 3 is manufactured (similarly in the case of the negative electrode 2), but the mixture is not applied from both ends of the length M, but is suitable at both ends in the length direction. Non-coated part (blank part) m1 and m2 where the length mixture is not applied
Is set. When the mixture is applied, the mixture has a relatively high viscosity, and therefore the mixture on the application nozzle side is pulled toward the current collector plate 8 by the viscosity at the end of the application portion. As a result, the ridges 6a, 6b and the lands in which the mixture has risen are formed at the end of the coating section. These ridges 6a, 6b and the like are hardened as they are without being flattened.

The spirally wound electrode body 1 is constructed by using the positive electrode 3 (the same applies to the negative electrode 2) having the ridges 6a and 6b formed on both ends in this manner. Therefore, this wound electrode body 1
In the secondary battery after the product is stored in the battery can, it does not matter if the pressure in the battery can is low,
If the internal pressure rises due to temperature rise in the battery can,
The ridges 6a, 6b and the like are strongly pressed against the separators 4, 5. As a result, the ridges 6a, 6b and the like pierce the separators 4, 5 and project to the opposite side, and when the ridges 6a, 6b, etc. contact the mixture layer of the adjacent electrodes, the negative electrode 2 and the positive electrode 3 are separated. It will be conducted and an internal short circuit will occur.

The present invention has been made in view of the above conventional problems, and the end of the separator of the wound electrode body is folded back, and the folded back portion is coated with the mixture layer of the electrode. By applying to the end portion, and by forming a structure in which the ridge portion or the like formed on the end portion is covered with a double layer of the separator so that the ridge portion or the like does not easily penetrate the separator, it is an object to solve the above problems. I am trying.

[0012]

[Means for Solving the Problems] In order to solve the above-mentioned problems and the like, and to achieve the above-mentioned object, claim 1 of the present application
The non-aqueous electrolyte secondary battery described is a wound electrode body formed by winding a belt-shaped current collector with a separator interposed between the strip-shaped electrodes in which the mixture layer is formed, and the wound electrode body. In a non-aqueous electrolyte secondary battery having a battery can to be housed, the end of the separator in the winding direction is folded back to the end of the electrode in the winding direction of the mixture layer of the electrode, or the end of the separator is adjacent to the end. It is characterized in that it is overlapped with the end of the separator so that the end of the mixture layer is covered with two separators.

In the non-aqueous electrolyte secondary battery according to claim 2 of the present application, the end portion of the separator is folded back to the side having the electrode,
Two of the separators and the adjacent separators, which are superposed on each other, are applied to the end portions of the mixture layer.

In the non-aqueous electrolyte secondary battery according to claim 3 of the present application, the end portion of the separator is folded back to the side opposite to the side having the electrode, and the two stacked separators are placed at the end portion of the mixture layer. It is characterized by applying.

In the non-aqueous electrolyte secondary battery according to claim 4 of the present application, the folded-back portion of the separator is provided at an outer peripheral side end portion in the winding direction of the wound electrode body, and the folded-back portion allows the positive electrode mixture layer to be formed. It is characterized in that the outer peripheral side end portion of is covered.

In the non-aqueous electrolyte secondary battery according to claim 5 of the present application, the portion where the mixture layer is not formed at the end of the electrode in the winding direction is less than 360 degrees from the outer end. Is characterized by.

In the non-aqueous electrolyte secondary battery according to claim 6 of the present application, LixMO ₂ (M = one or more elements selected from transition metals) is used for the positive electrode of the electrode, and lithium is used for the negative electrode of the electrode. It is characterized in that one or more materials selected from alloys or compoundable materials or carbonaceous materials that can be doped and dedoped with are used.

With the above structure, in the non-aqueous electrolyte secondary battery according to claim 1 of the present application, the end portion of the electrode mixture layer of the electrode is covered with the portion where the two separators are stacked. The ridges formed at the ends of the mixture layer can make it difficult to penetrate the separator, and even when the internal pressure increases due to temperature rise in the battery can, the ridges pierce the separator. Prevent it from protruding to the other side,
The ridge portion prevents the internal short circuit from occurring due to the positive electrode and the negative electrode being brought into conduction by contacting the mixture layer of the adjacent electrodes.

In the non-aqueous electrolyte secondary battery according to claim 2 of the present application, the end portion of the separator is folded back to the side having the electrode,
By applying the overlapping portion of the folded portion and the adjacent separator to the end portion of the mixture layer, the end portions of the two separators cover the ridge portion of the mixture layer, and the ridge portion pierces the separator. Prevent.

In the non-aqueous electrolyte secondary battery according to claim 3 of the present application, the end portion of the separator is folded back to the side opposite to the side having the electrode, and the polymerized portion of the folded portion is applied to the end portion of the mixture layer. Thus, the edge portion of one sheet is made twice as thick as the edge portion to cover the ridge portion of the mixture layer and prevent the ridge portion from breaking through the separator.

In the non-aqueous electrolyte secondary battery according to claim 4 of the present application, the outer peripheral side end portion of the separator is folded back, and the polymerized portion of the folded back portion is formed at the outer peripheral side end portion of the mixture layer. By applying the strip portion, the occurrence of an internal short circuit in the outer peripheral portion of the spirally wound electrode body that is most affected by the strip portion is prevented or suppressed.

In the non-aqueous electrolyte secondary battery according to claim 5 of the present application, the portion of the outer peripheral edge or the inner peripheral edge of the electrode where the mixture layer is not provided is less than 360 degrees, whereby the mixture layer The amount of decrease can be suppressed and the amount of decrease in the amount of electric power can be minimized.

In the non-aqueous electrolyte secondary battery according to claim 6 of the present application, LixMO ₂ is used for the positive electrode and an alloy capable of doping and dedoping lithium for the negative electrode, a compoundable material or a carbonaceous material. By using one or more kinds of materials described above, the cycle characteristics of lithium ions can be improved and energy efficiency can be increased.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 8 show an embodiment of the present invention. That is, FIG. 1 is a perspective view showing a spirally wound electrode body according to a first embodiment of the non-aqueous electrolyte secondary battery of the present invention, and FIG. 2 is an explanatory view showing a main part of the spirally wound electrode body of FIG. Three
1 is an explanatory view showing a cross section of the spirally wound electrode body of FIG. 1, FIGS. 4 and 5 are explanatory views of an outer peripheral side end portion of the spirally wound electrode body, and FIG. 6 is a first nonaqueous electrolyte secondary battery of the present invention. FIG. 7 is a perspective view showing a spirally wound electrode body according to a second embodiment of the non-aqueous electrolyte secondary battery of the present invention, and FIG. 8 is a sectional view of the spirally wound electrode body of FIG. 7. FIG.

As the non-aqueous electrolyte secondary battery of the present invention, for example, a lithium ion secondary battery can be cited, and FIG. 6 shows the lithium ion secondary battery in which the central portion is longitudinally sectioned. As shown in FIG. 6, a lithium ion secondary battery 10 showing a first embodiment of the non-aqueous electrolyte secondary battery of the present invention comprises a cylindrical battery can 11 and a cylinder housed in the battery can 11. -Shaped spirally wound electrode body 12 and a safety valve device 13 for preventing abnormal pressure rise and excessive charge inside the battery
And a terminal plate 14 that closes the opening of the battery can 11.

The battery can 11 is formed of a conductive metal such as iron Fe as a hollow cylindrical body having a bottom. A terminal portion 11a is provided on the bottom of the battery can 11 by slightly bulging the central portion outward in a circular shape. The inner surface of the battery can 11 is, for example, plated with nickel or coated with a conductive paint to form the battery can 1.
It is preferable to adopt a configuration in which the conductivity of No. 1 is increased. Also,
The outer peripheral surface of the battery can 11 is protected by being covered with an outer label formed of, for example, a plastic sheet or paper, or coated with an insulating paint.

The spirally wound electrode body 12 housed in the battery can 11 has a structure as shown in FIGS.
That is, the spirally wound electrode body 12 includes a positive electrode 15 and a negative electrode 16 which are formed in a strip shape, and two separators 17 and 18 which are also formed in a strip shape. One separator 17 is interposed between the positive electrode 15 and the negative electrode 16, and the other separator 17 is arranged on the side opposite to the one separator 17 of the positive electrode 15. By winding the laminated body thus laminated in four layers with the negative electrode 16 inside,
A spirally wound electrode body 12 is formed.

The positive electrode 15 has a strip-shaped positive electrode current collector 15a, and positive electrode mixture layers 15b applied to both surfaces of the positive electrode current collector 15a, as shown in FIG. 1
And 5c. As the positive electrode current collector 15a, for example, an aluminum foil having a thickness of 20 μm can be applied. The positive electrode mixture layer 1 is formed by uniformly applying the positive electrode mixture slurry on both surfaces of the positive electrode current collector 15a.
5b and 15c are formed. At this time, the positive electrode current collector 15a
A blank portion 19 is formed so that the positive electrode mixture slurry is not applied over a certain range at one end (winding end side) in the longitudinal direction of.

As the positive electrode active material of the positive electrode mixture, the following materials can be used. For example, a chalcogen compound with a transition metal containing an alkali metal, particularly an oxide of an alkali metal and a transition metal can be used. As the crystal structure of the compound, a layered compound or a spinel type compound is often used. As the layered compound, a compound represented by LixMO ₂ as a general formula can be used. Here, Li is lithium and O ₂ is oxygen. Further, x of Lix is 0.5 ≦ x ≦ 1.10.

Further, M is at least one element selected from transition metal elements, and more specifically, iron (F
e), cobalt (Co), nickel (Ni), manganese (Mn), copper (Cu), zinc (Zn), tin (Sn),
Chromium (Cr), vanadium (V) and titanium (Ti)
Etc. can be mentioned. And out of these groups
It is preferable to contain one or more selected from Fe, Co, Ni and Mn.

A positive electrode mixture slurry is prepared using such a positive electrode active material. This positive electrode mixture slurry is, for example,
86% by weight of powder LiCoO ₂ , 10% by weight of graphite as a conductive agent, and 4% by weight of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture, which was dispersed in N-methyl-2-pyrrolidone. It can be produced by This positive electrode mixture slurry is used as a positive electrode current collector 15
A blank portion 19 is formed on both surfaces of a so that the blank portion 19 is formed at the end of the electrode winding, and the coating is applied uniformly. After that, the positive electrode mixture slurry on both surfaces is dried, and then subjected to compression molding with a roller pressing machine, whereby the positive electrode 15 in the form of a strip is formed.

The negative electrode 16 is composed of a negative electrode current collector 16a which is also formed in a strip shape, and negative electrode mixture layers 16b and 16c which are applied to both surfaces of the negative electrode current collector 16a.
As the negative electrode current collector 16a, for example, a copper foil having a thickness of 10 μm can be applied. The negative electrode mixture layers 16b and 16c are formed by uniformly applying the negative electrode mixture slurry on both surfaces of the negative electrode current collector 16a. At this time, a blank portion is formed so that the negative electrode mixture slurry is not applied over a certain range to one end (winding end side) in the longitudinal direction of the negative electrode current collector 16a.

As the negative electrode active material of the negative electrode mixture, for example,
One or more negative electrode materials selected from alloys or compoundable materials or carbonaceous materials capable of doping (storing) and dedoping (leaving) lithium can be used. Examples of the negative electrode material capable of inserting and extracting lithium include a metal or semiconductor capable of forming an alloy or compound with lithium, or an alloy or compound thereof.

These metals, alloys or compounds are represented by the chemical formula DsEtLiu, for example. In this chemical formula, D is at least one of a metal element and a semiconductor element capable of forming an alloy or a compound with lithium.
Represents a species. Further, E represents at least one kind of metal element and semiconductor element other than lithium Li and D. Furthermore, the values of S, t, and u are s> 0, t ≧ 0, and u, respectively.
≧ 0.

Among them, the metal element or semiconductor element capable of forming an alloy or compound with lithium is preferably a group 4B metal element or semiconductor element, particularly preferably silicon or tin, and most preferably silicon. . Further, these alloys or compounds are also preferable, and specifically, SiB ₄ , SiB ₆ , Mg ₂ Si, Mg ₂ S.
n, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoS
i ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ S
i, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaS
Examples thereof include i ₂ , VSi ₂ , WSi _{2 and} ZnSi ₂ .

Further, as another example of the negative electrode material capable of inserting and extracting lithium, a carbon material, a metal oxide, a polymer material or the like can be cited. Examples of the carbon material include natural graphite, non-graphitizable carbon, artificial graphite, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, activated carbons and carbon blacks. Among these, the cokes include pitch coke, needle coke, petroleum coke, and the like. The term "calcined organic polymer compound" refers to a material obtained by carbonizing a polymer material such as phenols or furans by calcining at a suitable temperature. Further, examples of the metal oxide include iron oxide, ruthenium oxide, molybdenum oxide, tin oxide and the like. In addition, examples of the polymer material include polyacetylene, polypyrrole, and the like.

As the non-aqueous electrolyte, a non-aqueous solvent, a solid electrolyte, a polymer electrolyte or a liquid, solid or gel electrolyte in which an electrolyte is mixed or dissolved in a polymer compound can be used. Here, as the non-aqueous solvent, for example, ethylene carbonate, cyclic ester compounds such as γ-valerolactone, diethoxyethane, tetrahydrofuran,
Ether compounds such as 2-methyltetrahydrofuran and 1,3-dioxane, chain ester compounds such as methyl acetate and methyl propylene oxide, chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, or 2,4 -Difluoroanisole, 2,6-difluoroanisole, 4-proveratrol and the like can be used alone or as a mixed solvent of two or more kinds.

As the polymer material used for the gel electrolyte, for example, polyacrylonitrile and a copolymer of polyacrylonitrile can be used. Examples of the copolymerization monomer (vinyl diameter monomer) include, for example,
Examples thereof include vinyl acetate, methyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, itaconic acid, hydrogenated methyl acrylate, hydrogenated ethyl acrylate, acrylamide, vinyl chloride, vinylidene fluoride, vinylidene chloride and the like. Further, acrylonitrile butadiene rubber, acrylonitrile butadiene styrene resin, acrylonitrile chloride polyethylene propylene diene styrene resin, acrylonitrile vinyl chloride resin, acrylonitrile methacrylate resin, acrylonitrile acrylate resin and the like can be used.

Further, as the polymer material used for the gel electrolyte, polyvinylidene fluoride and a copolymer of polyvinylidene fluoride can be used. Examples of the copolymerization monomer include hexafluoropropylene and tetrafluoroethylene. As the polymer material used for the gel electrolyte, these may be used alone or in combination of two or more.

In order to form the gel electrolyte layer, a non-aqueous solvent such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, γ-butyl lactone, γ-valerolactone or a cyclic ester compound, or diethoxy is used. Ether compounds such as ethane, tetrahydrofuran, 2-methyltetrahydrofuran and 1,3-dioxane, chain ester compounds such as methyl acetate and methyl propylene oxide, chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, or 2,4-difluoroanisole, 2,6-difluoroanisole, 4-proveratrolol and the like can be used alone or as a mixed solvent of two or more kinds.

Further, in the gel electrolyte layer, when polyvinylidene fluoride is used as the gel electrolyte,
It is preferably formed using a gel electrolyte composed of a multi-component polymer in which polyhexafluoropropylene, polytetrafluoroethylene, etc. are copolymerized. Thereby, a gel electrolyte having higher mechanical strength can be obtained.

The electrolyte salt may be, for example, LiP.
F ₆ , LiAsF ₆ , LiBF ₄ , LiClO ₄ , Li
_{CF 3 SO 3, LiN (CnF} 2n + 1 SO 2) 2, LiC 4
Lithium salts such as F ₉ SO ₃ can be used alone or in combination of two or more. The amount of the electrolyte salt added may be adjusted so that the molar concentration in the non-aqueous electrolyte solution in the gel electrolyte is 0.8 to 2.0 mol / liter so as to obtain good ionic conductivity. preferable.

A negative electrode mixture slurry is prepared using such a negative electrode active material. This negative electrode mixture slurry is, for example,
90% by weight of graphite material powder and 10% by weight of polyvinylidene fluoride as a binder are mixed to prepare a negative electrode mixture, which is dispersed in N-methyl-2-pyrrolidone. it can. This negative electrode mixture slurry is uniformly applied to both surfaces of the negative electrode current collector 16a so that a blank part is formed at the end of the electrode winding.
After that, the negative electrode mixture slurry on both surfaces is dried, and then subjected to compression molding with a roller press machine to form the strip-shaped negative electrode 16.

As the separators 17 and 18, for example, a microporous polypropylene film can be used. The thickness of the separators 17, 18 is 25 μm
And these are interposed between the positive electrode 15 and the negative electrode 16. Then, the negative electrode 16, the separator 17, the positive electrode 15
Then, the separator 18 is laminated in this order, and this is wound from one end to the other end. Then, the winding end portion is fixed using the adhesive tape 20. As a result, the spirally wound electrode body 12 is formed.

At the time of winding the spirally wound electrode body 12 as described above, both ends of one separator 18 in the winding direction are respectively bent, and the bent portion 18a is, as shown in FIGS. The blank portion 19 of the above is overlapped from the mixture application end portion. That is, the tip of the bent portion 18 a of the separator 18 is connected to the mixture layers 15 b and 15 c of the positive electrode 15.
It is superposed on the above-mentioned ridge portion 6a formed in.

As a result, in the positive electrode mixture layer 15b on one side of the positive electrode 15, the ridge 6a is formed at the end in the winding direction.
The two separators 17 and 18 that are stacked on top of each other are applied. Then, the other positive electrode mixture layer 15c of the positive electrode 15
In the case of (2), two separators 17 and 18 are applied to the protrusion at the starting end in the winding direction.
In this way, the two separators 1 are attached to the protrusion 6a.
By applying 7 and 18, it is difficult for the ridge 6a to penetrate the separators 17 and 18, and a short circuit between adjacent terminals can be effectively prevented or suppressed.

In principle, the same applies to the negative electrode 16 as to the positive electrode 15. Therefore, the negative electrode 16
Similarly to the case of the positive electrode 15, the ridges 6a, 6b in the mixture layers 16b, 16c of
It is preferable to apply two sheets of separators 17 and 18 to 6b. However, the material of the positive electrode mixture is different from the material of the negative electrode mixture, and in general, the negative electrode mixture layer 16
The hardness of b and 16c is lower than the hardness of the positive electrode material mixture layers 15b and 15c. As a result, the negative electrode mixture layers 16b, 1
The probability that the ridges 6a and 6b of 6c break through the separators 17 and 18 is lower than that of the positive electrode material mixture layers 15b and 15c. Therefore, the occurrence rate of defects such as breakage and penetration of the separators 17 and 18 due to the protrusions of the negative electrode 16 is low, but it is needless to say that the present invention can be applied to the negative electrode 16.

The spirally wound electrode body 12 having such a structure has a large number of positive electrode leads 2 connected to the positive electrode current collector 15a.
2 and a large number of negative electrode leads 23 connected to the negative electrode current collector 16a. All positive electrode leads 22 are
The wound electrode body 12 is led out to the upper surface side which is one end in the axial direction, and all the negative electrode leads 23 are led out to the lower surface side which is the other end in the axial direction. Further, a pipe-shaped center pin 24 is formed in the hole at the center of the spirally wound electrode body 12.
Has been inserted. The upper insulator 25 is arranged on the upper surface of the spirally wound electrode body 12, and the lower insulator 26 is arranged on the lower surface thereof.

The outer diameters of the upper and lower insulators 25, 26 are slightly smaller than the outer diameter of the spirally wound electrode body 12, and the center hole 2 penetrating the front and back surfaces is formed at the center of each of them.
5a and 26a are provided. And the upper insulator 25
All the positive electrode leads 22 penetrate, and the lower insulator 26 penetrates all the negative electrode leads 23.
Such a wound electrode body 12 is housed inside the battery can 11 together with the upper and lower insulators 25 and 26. Then, the large number of negative electrode leads 23 protruding below the lower insulating plate 26 are
They are grouped together and fixed to the inner surface of the terminal portion 11a by a fixing means such as welding and electrically connected.

In the battery can 11, the lower insulating plate 26
Of the lower insulating plate 26, the center hole 24a of the center pin 24, and the center hole 2 of the upper insulating plate 25.
It communicates with the upper region of the upper insulating plate 25 via 5a. The safety valve device 13 and the terminal plate 14 are mounted on the opening of the battery can 11 in the upper region of the upper insulating plate 25 so as to overlap each other.

The safety valve device 13 and the terminal plate 14 are both formed in a disc shape, and the outer peripheral edges of the safety valve device 13 and the terminal plate 14 are held by a gasket 27 having a ring shape.
1 opening is closed. And the gasket 27
The opening of the battery can 11 is liquid-tightly sealed by caulking or laser welding the vicinity of the opening of the battery can 11 via.

The safety valve device 13 is composed of a cleaving valve 28 having a function of letting the gas inside the battery escape to the outside when a gas abnormally occurs inside the battery, and a shut-off valve 29 having a function of shutting off the current at the time of excessive charging. Has been done. Cleavage valve 28
Has a cleavage portion that is broken when a pressure higher than a predetermined pressure is applied, and the gas inside the battery is released to the outside by breaking the cleavage portion at a pressure higher than a predetermined pressure. Further, the shutoff valve 29, when an excessive current flows,
The current circuit is cut off to prevent current from flowing, and for example, a PTC element or the like can be applied.

To the shutoff valve 29 of the safety valve device 13, a large number of positive electrode leads 22 led out above the upper insulator 25 are gathered together, fixed by a fixing means such as welding, and electrically connected. ing. The inner side in the radial direction of the shutoff valve 29 is circular and bulges downward. Corresponding to this, the inner side in the radial direction of the terminal plate 14 has the same circular shape, but is bulged upward, which is opposite to the shutoff valve 29. The terminal plate 14 is provided with a gas vent hole 14a for letting out an abnormal gas inside the battery to the outside.

The lithium ion secondary battery 10 having such a structure can be easily manufactured, for example, as follows. First, the positive electrode 15 and the negative electrode 16 manufactured as described above are separated via the separators 17 and 18.
Negative electrode 16, separator 17, positive electrode 15 and separator 1
After stacking in the order of 8, this is wound a predetermined number of times, and the winding end portion is fixed with the adhesive tape 20. As a result, the spirally wound electrode body 12 is formed by spirally winding.

The center pin 24 is inserted into the central hole of the spirally wound electrode body 12, the insulators 25 and 26 are arranged above and below the center pin 24, and the insulator 25 and 26 are housed in the hole of the battery can 11. next,
A large number of negative electrode leads 23 are welded to the inner surface of the terminal portion 11 a of the battery can 11. In addition, the positive electrode lead 22 is connected to the safety valve device 13
Weld to. Next, the electrolytic solution is injected into the battery can 11.
This electrolytic solution can be prepared, for example, by dissolving the electrolyte salt LiPF6 at a concentration of 1 mol / liter in an organic solvent in which ethylene carbonate and methyl ethyl carbonate are mixed at a volume ratio of 5: 5.

Thereafter, the safety valve device 13 and the terminal board 14 are attached to the sealing gasket 27 whose surface is coated with asphalt.
And the opening of the battery can 11 is closed. Next, the safety valve device 13 and the terminal board 14 are fixed via the gasket 27 by caulking the opening of the battery can 11. As a result, the lithium-ion secondary battery 10 having a cylindrical outer diameter can be manufactured.

In such a lithium ion secondary battery 10, for example, when the charging cycle progresses too much and becomes overcharged, lithium metal is deposited on the surface of the negative electrode 16,
Since the negative electrode 16 becomes thicker, the outer diameter of the spirally wound electrode body 12 becomes larger. Then, the outer peripheral surface of the spirally wound electrode body 12 is attached to the battery can 11
By hitting the inner surface of the positive electrode 15, the protrusions of the positive electrode 15 and the negative electrode 16, in particular, the protrusions 6a and 6b of the positive electrode 15 are pressed against the adjacent separators 17 and 18.

However, the protrusions 6a, 6 of the positive electrode 15
Since the two separators 17 and 18 that are made of two sheets are in contact with b (the same applies to the protruding portion of the negative electrode), it is possible to prevent the separators 17 and 18 from being damaged by the protruding portions 6a and 6b. It can be prevented or effectively suppressed. As a result, conduction between adjacent electrodes due to breakage of the separator can be prevented, and internal short circuit of the battery can be prevented or effectively suppressed.

Next, test examples of the present invention and the conventional example will be described. In this test, 100 lithium ion secondary batteries 10 each having the above-described configuration of the present invention and 100 lithium ion secondary batteries each having a conventional general configuration were prototyped. Then, each of these secondary batteries was charged to a voltage of 4.2 V (volt), and after one month, the one whose voltage dropped to 4.15 V or less was counted as an internally shorted product. The results are shown in Table 1.

[0060]

[Table 1]

As is clear from the test results, 12 internal short-circuits were generated in the conventional structure product, but it was reduced to 3 internal short-circuits in the product of the present invention. Therefore,
According to the present invention, the number of short-circuited products can be reduced to 1/4 of that of the conventional structure product.

FIG. 5 shows another embodiment of the bent portion of the separator 18. In the above-described embodiment, an example was described in which the positive electrode 15 was folded inward by the separator 18 to form the inwardly bent portion 18a, but in this embodiment, the separator 1 is provided on the opposite side of the positive electrode 15.
8 is bent, and an outward bent portion 18b is formed so as not to wrap the positive electrode 15. With such a structure, the same effect as that of the above-described embodiment can be obtained.

FIG. 7 shows a spirally wound electrode body according to a second embodiment of the non-aqueous electrolyte secondary battery of the present invention, and FIG.
FIG. 3 is an explanatory view showing a cross section of the wound electrode body of FIG. As shown in FIG. 7, the spirally wound electrode body 32 has the same structure as that of the spirally wound electrode body 12 described above, and is different from the spirally wound electrode body 12 in that The point is that the rotated electrode body is crushed from the side and wound in a flat shape.

That is, the wound electrode body 32 is the wound electrode body 12
Similarly to, the positive electrode 15 and the negative electrode 16 formed in a strip shape,
Two separators 17 and 18 which are also formed in a strip shape
It has and. Then, one separator 17 is interposed between the positive electrode 15 and the negative electrode 16, and the other separator 18 is superposed on the positive electrode 15 to be laminated in four layers. The four-layer laminated body is wound with the negative electrode 16 inside to form a spiral shape, and then pressed laterally to be flattened. As a result, the spirally wound electrode body 32 wound in a flat shape having an oval cross section is formed.

The spirally wound electrode body 32 having such a structure
Can be used as a polymer secondary battery, for example, by accommodating an aluminum laminate film in a bag-shaped exterior material. Here, the polymer secondary battery is a positive electrode,
A polymer (polymer material) is used for at least one of the three elements of the negative electrode and the electrolyte. Generally, the polymer is used for the electrolyte or the positive electrode. With such a flat wound electrode body 32, the same effects as those of the wound electrode body 12 and the secondary battery thereof according to the above-described embodiments can be obtained.

The spirally wound electrode body 32 is housed in, for example, a rectangular (rectangular, square, etc.) battery can, an elliptical or oval battery can, or a can body having another shape, in addition to the above-mentioned exterior material. It can also be used.

As described above, the present invention is not limited to the above embodiment. For example, although the cylindrical secondary battery in which the battery can has a cylindrical shape is described in the above embodiment, the battery can is Of course, the rectangular parallelepiped can be applied to the prismatic secondary battery. As described above, the present invention can be variously modified without departing from the spirit thereof.

[0068]

As described above, claim 1 of the present application
According to the non-aqueous electrolyte secondary battery described, since the end portion of the electrode mixture layer of the electrode is configured to be covered with the portion where two separators are stacked, the ridge portion formed at the end portion of the electrode mixture layer forms the separator. It can be hard to penetrate. As a result, even when the internal pressure becomes high due to the temperature rise in the battery can,
It is possible to prevent the ridges from breaking through the separator and projecting to the opposite side, and prevent the ridges from coming into contact with the mixture layer of the adjacent electrodes to electrically connect the positive electrode and the negative electrode, thereby causing an internal short circuit. The effect that it can be prevented can be obtained.

According to the non-aqueous electrolyte secondary battery of claim 2 of the present application, the end portion of the separator is folded back to the side where the electrode is present, and the polymerized portion of the folded portion and the adjacent separator is the end of the mixture layer. Since the structure is applied to the two parts, the ends of the two separators cover the ridges of the active material and prevent the ridges from breaking through the separator, and the positive electrode and the negative electrode are electrically connected to each other to cause an internal short circuit. Can be prevented.

According to the non-aqueous electrolyte secondary battery of claim 3 of the present application, the end portion of the separator is folded back to the side opposite to the side having the electrode, and the polymerized portion of the folded portion is positioned at the end portion of the mixture layer. Since the configuration is such that the end of one separator is
It is possible to double the thickness to cover the ridges of the mixture layer, prevent the ridges from breaking through the separator, and prevent the positive electrode and the negative electrode from being electrically connected to each other to cause an internal short circuit.

According to the non-aqueous electrolyte secondary battery of claim 4 of the present application, the outer peripheral end of the separator is folded back, and the polymerized portion of the folded back portion is formed at the outer peripheral end of the mixture layer. Since the configuration is applied to the protruding portion, it is possible to prevent or suppress the occurrence of an internal short circuit in the outer peripheral portion of the wound electrode body that is most affected by the protruding portion.

According to the non-aqueous electrolyte secondary battery of claim 5 of the present application, since the portion where the mixture layer is not provided at the outer peripheral edge or the inner peripheral edge of the electrode is less than 360 degrees, It is possible to suppress the reduction amount of the agent layer and minimize the reduction amount of the electric power amount.

According to the non-aqueous electrolyte secondary battery of claim 6 of the present application, an alloy, a compoundable material or a carbonaceous material which uses LiMO ₂ for the positive electrode and can be doped and dedoped with lithium for the negative electrode. Since one or more materials selected from the above are used, the cycle characteristics of lithium ions can be improved and the energy efficiency can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a wound electrode body according to a first embodiment of a non-aqueous electrolyte secondary battery of the present invention.

FIG. 2 is an explanatory diagram showing a main part on the outer peripheral side of one embodiment of the wound electrode body according to the first embodiment of the non-aqueous electrolyte secondary battery of the present invention.

FIG. 3 is an explanatory diagram in which an embodiment of the spirally wound electrode body according to the first embodiment of the non-aqueous electrolyte secondary battery of the present invention is laterally cross-sectioned.

FIG. 4 is an explanatory view showing an example of an outer peripheral side end portion of a spirally wound electrode body according to a first embodiment of the non-aqueous electrolyte secondary battery of the present invention.

FIG. 5 is an explanatory view showing another example of the outer peripheral side end portion of the spirally wound electrode body according to the first embodiment of the non-aqueous electrolyte secondary battery of the present invention.

FIG. 6 is a vertical cross-sectional view showing a first embodiment of the non-aqueous electrolyte secondary battery of the present invention.

FIG. 7 is a perspective view showing an example of a wound electrode body according to a second example of the non-aqueous electrolyte secondary battery of the present invention.

FIG. 8 is an explanatory view in which one embodiment of a spirally wound electrode body according to a second embodiment of the non-aqueous electrolyte secondary battery of the present invention is laterally cross-sectioned.

FIG. 9 is an explanatory diagram showing a positive electrode original plate for explaining a manufacturing process of an electrode related to a wound electrode body of a non-aqueous electrolyte secondary battery.

FIG. 10 is an explanatory diagram showing a positive electrode for explaining a manufacturing process of an electrode related to a wound electrode body of a non-aqueous electrolyte secondary battery.

FIG. 11 is a perspective view showing a wound electrode body of a conventional non-aqueous electrolyte secondary battery.

FIG. 12 is an explanatory diagram showing a main part on an outer peripheral side of a wound electrode body according to a conventional non-aqueous electrolyte secondary battery.

FIG. 13 is an explanatory view showing an outer peripheral side end of a wound electrode body according to a conventional non-aqueous electrolyte secondary battery.

[Explanation of symbols]

6a, 6b ridge portion, 10 lithium ion secondary battery (non-aqueous electrolyte secondary battery), 11 battery can, 12, 3
2 winding electrode body, 13 safety valve device, 14 terminal plate,
15 positive electrode, 15a positive electrode current collector, 15b, 15
c positive electrode mixture layer, 16 negative electrode, 16a negative electrode current collector, 16b, 16c negative electrode mixture layer, 17, 18 separator, 18a bent portion

Claims (6)

[Claims] 1. A wound electrode body in which a separator is interposed between strip-shaped electrodes each having a mixture layer formed on a strip-shaped current collector, and a battery can containing the spirally wound electrode body. In a non-aqueous electrolyte secondary battery comprising: an end of the separator in the winding direction is folded back to an end of the mixture layer of the electrode in the winding direction, or the end of the separator is adjacent to the end. A non-aqueous electrolyte secondary battery, characterized in that the non-aqueous electrolyte secondary battery is superposed on the end portion of the separator so that the end portion of the mixture layer is covered with two separators. 2. The end portion of the separator is folded back to the side where the electrode is present, and two sheets of the separator and an adjacent separator, which are superposed on each other, are applied to the end portion of the mixture layer. 1. The non-aqueous electrolyte secondary battery described in 1. 3. An end of the separator is folded back to a side opposite to a side where the electrode is provided, and two superposed sheets of the separator are applied to an end of the mixture layer. Non-aqueous electrolyte secondary battery. 4. The folded portion of the separator is provided at an outer peripheral side end portion of the wound electrode body in the winding direction,
The non-aqueous electrolyte secondary battery according to claim 1, 2 or 3, wherein the folded-back portion covers the outer peripheral side end of the positive electrode material mixture layer. 5. A portion of the end of the electrode in the winding direction where the mixture layer is not formed is less than 360 degrees from the end on the outer peripheral side. The non-aqueous electrolyte secondary battery described. 6. LixMO ₂ (M = one or more elements selected from transition metals) is used for the positive electrode of the electrode, and an alloy or compound capable of being doped and dedoped with lithium is used for the negative electrode of the electrode. The non-aqueous electrolyte secondary battery according to claim 1, wherein one or more materials selected from possible materials or carbonaceous materials are used.