JPH11219694A - Winding type cylindrical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the shape of a lead piece member to connect an electrode plate of a battery with an external terminal. SOLUTION: This battery is equipped with a bunch of electrode plates formed by winding a band-shaped positive electrode plate 2 and negative electrode plate 3 through a separator 4, and a plurality of lead pieces 1 are led out per electrode plate from the side edge of the positive electrode plate 2 and/or negative electrode plate 3 in the direction perpendicular to the winding direction and are connected electrically with an external terminal. Each lead piece 1 is formed widening from the tip toward the root at the electrode plate side edge. It is preferred that the space between adjoining lead pieces 1 having the same polarity is substantially zero. This can be effectively applied to a lithium ion battery-in particular, a lithium ion battery whose positive electrode active material is based on lithium manganate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wound cylindrical battery.

[0002]

2. Description of the Related Art Conventionally, in the field of rechargeable secondary batteries, lead-acid batteries, nickel-cadmium batteries, nickel-
Aqueous solution batteries such as hydrogen batteries were the mainstream. However, in recent years, with the rapid spread of mobile phones and notebook personal computers, smaller and higher-capacity batteries have been required. In response to such demands, non-aqueous electrolyte-based lithium ion batteries using a lithium transition metal composite oxide such as lithium cobalt oxide for the positive electrode and a carbon material for the negative electrode have been developed. A lithium ion battery using a carbon material for the negative electrode has a lower energy density per unit volume than a secondary battery using metallic lithium for the negative electrode, but is safer and has a higher energy density than conventional aqueous batteries. It has the advantage of being, and is spreading rapidly.

In a non-aqueous electrolyte-based lithium ion battery having an ion conductivity that is inferior to that of an aqueous solution, the thickness of the electrode plate is reduced as much as possible to increase the area of the electrode plate, and the distance between the electrode plates is reduced to reduce the battery. The internal resistance is reduced to maintain high output characteristics without impairing the energy density per unit volume. In order to reduce the thickness of the electrode plate as much as possible, a technique in which a current collector is made of metal foil and an active material mixture is uniformly distributed on both surfaces thereof is generally applied. When the electrode area is increased, it becomes difficult to secure current collection from the current collector to the battery external terminal.
For example, when the current path is formed by one lead piece as disclosed in Japanese Patent Application Laid-Open No. Hei 6-310142, the current collecting property from the electrode plate position farthest from the lead piece is increased from the electrode plate position near the lead piece. Is inferior to the current collecting ability of Such a drawback is not so much a problem with a small battery having a rated capacity of up to 1000 mAh used as a power source for a notebook personal computer or a mobile phone, but has a problem with a large-capacity large battery used as a power source for an electric vehicle. . Therefore,
For example, in Japanese Unexamined Patent Publication No. 9-92335, an active material mixture-uncoated portion (exposed portion of a metal foil current collector) is provided at a long side edge of a belt-shaped positive / negative electrode plate, and a predetermined portion is formed on the uncoated portion. It has been proposed that a plurality of strip-shaped lead pieces be formed at predetermined intervals by making notches at intervals to improve the current collecting property uniformly over the entire electrode plate.

[0004]

However, the above-mentioned Japanese Patent Application Laid-Open No.
If the technique of Japanese Patent No. 92335 is applied, it is difficult to connect the lead pieces and the battery external terminals. The connection operation is an operation of collecting a large number of lead pieces made of metal foil at a predetermined location and connecting the lead pieces to a battery external terminal by means such as welding. In performing such an operation, if the shape stability of the lead pieces is poor, it is difficult to collect the lead pieces at the predetermined location. In particular, when the lead piece is a metal foil having particularly poor shape stability, the operation is extremely difficult. The problem to be solved by the present invention is to provide an electrode group in which a strip-shaped positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, and the positive electrode plate and / or
Or, from the side edge of the negative electrode plate, in a direction perpendicular to the winding direction,
In a wound cylindrical battery in which a plurality of lead pieces are led out for each electrode plate and the lead pieces are electrically connected to battery external terminals, a lead piece for connecting the electrode plate and the battery external terminal. The purpose is to stabilize the shape of the member.

[0005]

Means for Solving the Problems In order to solve the above problems, a wound cylindrical battery of the present invention comprises an electrode group in which a strip-shaped positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween. A plurality of lead pieces 1 are led out from one side edge of the plate and / or the negative electrode plate in a direction perpendicular to the winding direction for each electrode plate, and the lead pieces 1 are electrically connected to battery external terminals. The lead piece 1 is characterized in that the shape of the lead piece 1 becomes wider from the tip to the base of the side edge of the electrode plate. The lead piece 1 may be integrally extended from the current collector of the electrode, or may be fixed to a side edge of the current collector by welding or the like.

[0006] The lead piece 1 is not formed in a strip shape, but is made wider from the tip end toward the base of the side edge of the electrode plate, so that the electrode plate is bent by winding and the lower end of the lead piece 1 (electrode side). Will follow. When a portion that protrudes in the width direction from the tip of the lead piece 1 is bent along with the bending of the electrode plate, the bent portion acts to stabilize (support) the entire lead piece 1 in its length direction. Thereby, the shape of the lead piece 1 member after the winding step is stable even when the lead piece 1 is connected to the battery external terminal. Also, in the case where the lead piece 1 is integrally extended from the current collector, it is considered that by having the above-described configuration, there is also an advantage that cutting at the root portion of the lead piece can be suppressed as compared with a strip-shaped lead piece. Can be

Further, by realizing the above configuration in a form as shown in the front view of the electrode plate shown in FIGS. 1 (a) and 1 (b), for example, It is considered that the current collecting property of the plate is improved. The reason is that there is substantially no space between the adjacent lead pieces 1 at the base of the electrode plate side edge.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail by taking a cylindrical lithium ion battery as an example with reference to the drawings. (Preparation of positive electrode plate) Lithium manganate (L
iMn ₂ O ₄ ) To 100 parts by weight of powder, 10 parts by weight of flaky graphite (average particle size: 20 μm) as a conductive agent and 10 parts by weight of polyvinylidene fluoride as a binder were added, and N was added as a dispersion solvent. The slurry obtained by adding and kneading methylpyrrolidone was applied to both sides of an aluminum foil having a thickness of 20 μm.
At this time, an uncoated portion having a width of 30 mm was left on one side edge in the electrode plate length direction. After drying, pressing and cutting, the width is 130m.
m, a length of 2000 mm, and a positive electrode plate 2 having a thickness of 200 μm in the active material application portion. A cutout is made in the uncoated portion in the shape shown in FIG. The remaining portion of the notch becomes a lead piece 1 that becomes wider from the tip toward the base of the electrode plate side edge.
If one lead piece 1 is regarded as an isosceles triangle, its bottom is 10 mm and its height is 30 mm.

(Preparation of negative electrode plate) Graphite powder 100
10 parts by weight of polyvinylidene fluoride as a binder was added to parts by weight, N-methylpyrrolidone as a dispersion solvent was added thereto, and a kneaded slurry was applied to both sides of a rolled copper foil having a thickness of 10 μm. At this time, a width of 30
mm was left uncoated. Thereafter, drying, pressing and cutting were performed to obtain a negative electrode plate 3 having a width of 135 mm, a length of 2200 mm, and a thickness of the active material application portion of 130 μm. Fig. 1 (a)
Make a notch in the shape shown in The remaining portion of the notch becomes a lead piece 1 that becomes wider from the tip toward the base of the electrode plate side edge. If one lead piece 1 is regarded as an isosceles triangle, its bottom is 10 mm and its height is 30 mm.

(Preparation of Battery) A positive electrode plate 2 and a negative electrode plate 3 prepared as above are separated from a polyethylene separator 4 having a thickness of 40 μm.
And wound as shown in FIG. The lead pieces 1 of the positive electrode plate 2 and the lead pieces 1 of the negative electrode plate 3 are wound so as to be located at both ends of the winding group. Thereafter, the winding group is inserted into a cylindrical battery container. All of the lead pieces 1 led out of the positive electrode plate 2 are brought into contact with the inner peripheral side surface of the cylindrical positive electrode external terminal (integrated with the battery upper lid) substantially on the extension of the central axis of the winding group. Then, the lead piece 1 is deformed. In the state of the winding group, the lead piece 1 was stable in shape. In addition, when the lead piece 1 is subsequently deformed, since the vicinity of the tip of the lead piece 1 is narrower than the vicinity of its base, the deformation there is easy. In other words, the vicinity of the base of the lead piece 1 was firmly stable, and the vicinity of the tip was easy to deform, which was an ideal handling property. After the contact, the lead piece 1 and the positive electrode external terminal were ultrasonically welded to obtain electrical continuity. The operation of connecting the negative electrode external terminal and the lead piece 1 derived from the negative electrode plate 3 was also performed in the same manner as the above-described operation of connecting the positive external terminal and the lead piece 1 derived from the positive electrode plate 2. The properties near the root portion and the tip portion of the lead piece 1 there were similar to those of the lead piece 1 on the positive electrode plate side.

Thereafter, the battery container was sealed with the upper lid, a predetermined amount of electrolyte was injected into the battery container from the liquid inlet on the upper lid, and the liquid inlet was sealed, thereby producing a cylindrical lithium ion battery. As the electrolyte, lithium hexafluorophosphate (Li) was introduced into a mixed solution of ethylene carbonate and dimethyl carbonate.
PF ₆₎ was used after dissolving 1 mole / liter. The rated capacity of this battery is 10 Ah.

In the present embodiment, the present invention is applied to the lead pieces of the polar plates of both polarities. However, when connecting the lead pieces to the external terminals of the battery, the present invention is applicable to a battery having a structure in which the shape of the lead piece members does not need to be stabilized. May be only one polar plate. An example of a battery structure that does not require stabilizing the shape of the lead piece member when connecting the lead piece and the battery external terminal is that a cylindrical battery container also serves as the negative electrode external terminal, and the outermost periphery of the winding group is the negative electrode surface. And
In this structure, the inner wall of the battery container and the negative electrode surface are electrically connected by pressure welding. In this example, a lithium ion battery is illustrated, but the battery system is not limited. However, the application of the present invention is particularly effective for a lithium ion battery because it is necessary to increase the electrode area as described above, and it is highly necessary to provide a plurality of lead pieces on one electrode plate to improve the current collecting property. It is.

In this example, lithium manganate was used for the positive electrode, graphite was used for the negative electrode, and lithium hexafluorophosphate dissolved at 1 mol / l in a mixed solution of ethylene carbonate and dimethyl carbonate was used for the electrolyte. The method for producing the battery of the present invention is not particularly limited, and any of binders, positive and negative electrode active materials, and non-aqueous electrolytes which are commonly used can be used. However, when lithium manganate, which is lower in cost than lithium cobaltate, is used as the positive electrode active material, the present invention is particularly considered to be effective (including partially substituted materials with other elements).
This is because lithium manganate generally has lower electron conductivity than lithium cobalt oxide, lithium nickelate, or the like, and is expected to improve the conductivity of an electrode plate containing the same. In this example, the rated capacity is 1000
Although a large non-aqueous electrolyte battery having a rated capacity of 10 Ah exceeding mAh is described, the configuration of the present invention can be applied to a small non-aqueous electrolyte battery having a rated capacity of 1000 mAh or less. The effect of improving power efficiency is obtained.

Examples of the binder that can be used in other than this example include Teflon, polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene /
Examples include butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethylcellulose, various latexes, polymers such as acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, and chloroprene, and mixtures thereof. The positive electrode active material that can be used in other than this example is a material into which lithium can be inserted and desorbed, and a material into which a sufficient amount of lithium has been inserted in advance is preferable. For example, a lithium transition metal composite oxide, such as a lithium-cobalt composite oxide, a lithium-nickel composite oxide, a lithium-manganese composite oxide, or a lithium-vanadium composite oxide. Further, a material in which a part of these lithium transition metal composite oxides is substituted with another element may be used. There is no particular limitation on the negative electrode active material that can be used other than in this example. For example, lithium metals, lithium alloys, various graphite materials, carbonaceous materials such as coke, and conductive polymers such as polyacetylene are suitable.

As an electrolytic solution, an electrolytic solution obtained by dissolving a general lithium salt as an electrolyte in an organic solvent is used. However, the lithium salt or organic solvent used is not particularly limited. For example, as the electrolyte, LiClO ₄ ,
LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C
_{6 H 5) 4, CH 3} SO 3 Li, CF 3 SO 3 Li and the like or a mixture thereof is used. As the organic solvent, propylene carbonate, ethylene carbonate, 1,2-
Dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethylether, sulfolane, methylsulfolane, acetonitrile, propionitonyl and the like, or two or more thereof Is used.

In this embodiment, the shape of the lead piece 1 is shown in FIG.
Although a triangle as shown in FIG. 1 is used, a trapezoid as shown in FIG. Further, in this example, the interval between the adjacent lead pieces 1 was eliminated, but as shown in FIGS. 1C and 1D, the shape of the lead pieces 1 was triangular or trapezoidal.
An interval may be provided between them. 1A and 1B, R is provided at a connecting portion (a valley at the base of the lead piece 1) of the adjacent lead pieces 1 (substantially adjacent lead pieces 1).
It is preferable that the base of the lead piece 1 is hardly cut. Fig. 1 (c), (d)
R is provided at the base of the lead piece 1 in
It is also preferable to obtain the same effect as described above by adding a radius from the side edge of the electrode plate to the side edge of the lead piece 1. Further, other than the shape of the lead piece 1 shown in FIG. 1, the effect of the present invention can be obtained if the shape is wider from the tip toward the base of the side edge of the electrode plate. For example, in FIG. 1A, the tip of the lead piece 1 has a rounded shape, or the side of the lead piece 1 draws an arc. In making the lead piece 1 wider toward the base of the side edge of the electrode plate, the ratio of the width of the tip of the lead piece 1 to the width of the electrode plate side of the lead piece 1 is appropriately determined according to the material and thickness of the lead piece 1 to be used. It is determined.

[0017]

According to the present invention, a plurality of lead pieces are led out from the side edge of the positive electrode plate and / or the negative electrode plate for each electrode plate, and the positive electrode plate and the negative electrode plate are wound via a separator. In the wound cylindrical battery provided with the turned electrode group, the shape of the lead piece member could be stabilized when the lead piece was connected to the battery external terminal. Further, in a configuration in which the interval between adjacent lead pieces having the same polarity is substantially eliminated, improvement in current collecting performance can be expected. Further, in the case where the lead piece is integrally extended from the current collector, the configuration of the present invention has an advantage that the cut at the root of the lead piece can be suppressed as compared with the case where the shape of the lead piece is rectangular.

[Brief description of the drawings]

FIG. 1 is a front view of an electrode plate according to the present invention.

FIG. 2 is a diagram showing a state where a positive electrode plate and a negative electrode plate are wound via a separator.

[Explanation of symbols]

 1. Lead piece 2. Positive electrode plate 3. Negative electrode plate 4. Separator

Claims (7)

[Claims] An electrode group comprising a strip-shaped positive electrode plate and a negative electrode plate wound with a separator interposed therebetween, and a lead extending from a side edge of the positive electrode plate and / or the negative electrode plate in a direction perpendicular to the winding direction. A plurality of pieces are led out for each electrode plate, and the lead piece is electrically connected to an external terminal of the battery. A wound cylindrical battery having a width increasing toward a base of the battery. 2. The base of the electrode plate side edge portion, wherein there is a space between adjacent lead pieces, and R is provided from the electrode plate side edge portion to the lead one side edge portion.
The wound cylindrical battery according to the above. 3. The device according to claim 1, wherein there is no space between adjacent lead pieces at the base of the side edge of the electrode plate.
The wound cylindrical battery according to the above. 4. The wound cylindrical battery according to claim 3, wherein a radius is provided at a valley of a root of the adjacent lead. 5. The battery according to claim 1, wherein the battery is a lithium ion battery.
A wound cylindrical battery according to any one of claims 1 to 4. 6. The winding according to claim 5, wherein at least the shape of the positive electrode plate lead piece is wider toward the base of the side edge of the electrode plate, and the positive electrode active material is mainly composed of lithium manganate. Type cylindrical battery. 7. The wound cylindrical battery according to claim 1, wherein the rated capacity of the battery is more than 1000 mAh.