JPH11111259A - Winding type battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To multiply collect an electric current from a current collecting body in a highly reliable condition by forming plural places of current collecting lead groups by gathering plural same polarity current collecting leads derived from an electrode end part in the direction orthogonal to the winding direction, in an electrode group, and connecting the current collecting lead groups to external terminals. SOLUTION: A winding electrode group 8 is obtained by winding a positive electrode 1 and a negative electrode 2 through a polyethylene microporous film separator 3. The winding electrode group 8 is housed in a battery vessel 4 by bending a negative electrode current collecting lead 2' in the winding center direction. Current collecting lead groups 11 are connected to external terminals 5 of integral times the number of current collecting lead groups 11. In its connecting condition, a current collecting lead is not substantially curved, or is curved only in the lengthwise direction without being substabtially twisted. The external terminals 5 are integrally formed with a stainless steel battery cover through polypropylene insulating packing 6. An end part of a battery lid 7 and an opening part of the battery vessel 4 are fitted together, and they are sealed after an electrolyte is poured from a filler hole, and a battery is sealed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wound battery,
In particular, it relates to improvement of the current collecting structure.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a higher energy density as a power source for portable equipment and the like, and in order to fill a limited space in a battery with more power generating material, a thin electrode current collector is required. Is being planned. In particular, a metal foil having a thickness of 10 to 20 μm is used for a current collector of a lithium ion secondary battery which has been receiving attention as a high energy density battery. In addition, lithium-ion secondary batteries are being studied for use not only in small drive power supplies but also in large-capacity applications, for example, for power storage and electric vehicles, and their output characteristics are required to be improved. The current collecting structure is important for improving the output characteristics. As a current collecting structure of a conventional battery, in a battery having an electrode group in which a strip-shaped positive electrode and a negative electrode are spirally wound with a separator interposed therebetween, a rectangular current collector is applied to the current collector after the active material is applied to the surface. The lead is attached by welding at one place, and the current collecting lead is configured to protrude from the separator. Then, the current collecting lead is connected to an external terminal (such as a battery container, etc.).
There is a method (single current collection) of forming a current path by connecting to a battery terminal (a member called a battery terminal from the appearance of the battery).

[0003] In particular, in a battery or the like for which discharge at a rate higher than one hour rate is required, the end of the current collector protrudes beyond the projected portion of the separator (separator end) of the wound electrode group, and the projection is formed there. There is a method (multi-current collection) of joining a plurality of disk-shaped current collection leads having resistance to each other by resistance welding. According to this method, since a large number of the current supply paths can be secured, there is an advantage that the resistance loss of the current can be reduced even when a large current flows. It is difficult to apply the multi-current collection to a battery using a metal foil as a current collector because the strength of the current collector end is weak. Therefore, when trying to improve high-rate discharge characteristics in a wound battery using a metal foil as a current collector,
It is necessary to adopt a multi-collection of a form different from the above-mentioned multi-collection. In Japanese Patent Application Laid-Open No. 9-92335, a plurality of strip-shaped current collecting leads are provided at predetermined intervals at an end portion of a current collector made of a metal foil, and these are connected to a disk-shaped external terminal to reduce internal resistance. Propose technology.

[0004]

However, in the above-mentioned technology, the number of connection points between the current collecting lead and the disk-shaped external terminal is large, so that the probability of poor connection is high, and there is a problem that reliability is lacking. The problem to be solved by the present invention is a wound type battery comprising a wound electrode group using a metal foil current collector,
Multi-collection from the current collector is realized with high reliability,
It is to improve the high rate discharge characteristics.

[0005]

Means for Solving the Problems To solve the above problems, a positive electrode 1 according to the present invention, in which an active material is arranged on the surface of a metal foil current collector.
And a wound battery comprising an electrode group in which the negative electrode 2 is spirally wound with a separator 3 interposed therebetween, wherein the electrode group comprises a plurality of electrodes of the same polarity derived from an electrode end in a direction perpendicular to the winding direction. The present invention is characterized in that the current collecting lead group 11 includes two to six current collecting lead groups 11, and the current collecting lead group 11 is connected to the external terminal 5. By adopting the above configuration, it is possible to avoid the problem that the number of connection points between the current collecting lead and the external terminal is large in the technique disclosed in JP-A-9-92335.

The above-mentioned metal foil current collector is a conductive foil, film, plate or the like made of a single metal or alloy. The above "derived" means that the current collecting lead is derived from the current collector, that is, a state in which a part of the current collector member is cut into a current collecting lead shape, or at an electrode end in a direction orthogonal to the winding direction. It means a state in which the current collecting lead members are connected by means such as welding. The above-mentioned "collecting leads are assembled" means that a plurality of collecting leads composed of a conductive foil, a film, a plate, or the like made of a single metal or an alloy can be used for operations such as lamination and integration. Close, contacted, or connected. The connection means that electrical continuity between the current collecting lead and the external terminal 5 is realized by means such as resistance welding or ultrasonic welding.

In the above configuration, the side surface of the external terminal 5 at the portion to which the current collecting lead is connected is flat, and in the connected state, each current collecting lead is not substantially curved or substantially twisted. It is preferable to bend only in the length direction without having to do so. The reason for this is that the current collecting lead group 11
This is because, when the external terminal 5 formed of a flat surface is connected, no extra stress is applied to the current collecting lead group 11 in a lateral direction, an oblique direction, a rotating direction, and the like, and defects such as breakage of the current collecting lead can be suppressed. The surface of the current collecting lead group 11 refers to an external terminal 5 in a state where a plurality of current collecting leads are assembled in a form such as lamination.
Surface that connects to In the connection state, the flat portion on the side surface of the external terminal 5 and the lead-out location of the current collecting lead may be such that each current collecting lead is not substantially curved or substantially twisted without being twisted. In order to bend only in the vertical direction, for example, the current collecting lead is extended from the outside of the wound electrode group 8 toward the external terminal 5 from a positional relationship of being substantially parallel to each other as shown in the top view of FIG. It can be realized by bending in the direction and contacting and connecting to the flat part on the side surface of the external terminal 5 while forming the current collecting lead group 11. By doing so, the above-described extra stress can be avoided and the flat surface and the surface of the current collecting lead group 11 can be brought into contact.

In the above configuration, it is preferable that the adjacent current collecting lead groups 11 are located at substantially equal angles from the center of the winding. This means that, for example, when the current collecting lead group 11 has two locations, they are located facing each other across the center of the winding (in a direction substantially 180 ° from the center of the winding). When the current collecting lead group 11 has three to six locations, they are substantially equiangular from the center of the winding (when the current collecting lead group 11 is three, substantially 120 degrees from the center of the winding).
°, substantially 90 ° in four places, substantially 72 ° in five places, and substantially 60 ° in six places). This corresponds to the external terminal 5 in FIG.
This is a state where the current collecting lead is connected to the side surface. In this case, it can also be expressed that the distances between the current collecting lead groups 11 are equal. However, a state in which the distance between the current collecting lead groups 11 is different may be used. For example, in FIG.
This is the case where one of the electrodes 1 is derived only from near the end of the wound electrode group 8, and the other one of the current collecting lead groups 11 is derived only from near the center of the wound electrode. With such a preferable configuration, the current collecting lead group 11 is connected to the external terminals 5.
Workability at the time of connection to the electrodes becomes the best, or the distribution of current drawn from the inside of the electrode is easily made uniform. When realizing the preferable configuration, the shape of the external terminal 5 at the portion to which the current collecting lead is connected is an integral multiple prism of one or more of the number of the current collecting lead group 11, and the flat portion on the side surface of the prism is provided. It is more preferable that the current lead group 11 is connected, and in the connected state, each current collecting lead is substantially not curved or curved only in the length direction without causing substantial twisting. The reason for this is that the above-described current collecting lead group 11
It is preferable that the side surface of the external terminal 5 of the portion to be connected is flat, and the current collecting lead is not substantially curved in the connected state, or is curved only in the length direction without substantially twisting. The reason is the same.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows that the wound electrode group 8 is built in the battery case 4, the positive electrode active material is a transition metal composite oxide containing lithium, and the negative electrode active material is a carbon material capable of inserting and removing lithium ions. FIG. 2 is a diagram showing a cross section of a cylindrical wound lithium ion battery in which the charge / discharge reaction participating material is lithium for both the positive electrode active material and the negative electrode active material, and the electrolyte is a non-aqueous electrolyte. A method for producing the cylindrical wound battery will be described in detail.

(Preparation of Positive Electrode A) The positive electrode A was prepared as follows. 88 parts by weight of lithium cobaltate (LiCoO ₂ ) powder, 8 parts by weight of graphite powder, and 4 parts by weight of polyvinylidene fluoride are dispersed in an N-methylpyrrolidone solvent to prepare a positive electrode mixture slurry. This positive electrode mixture slurry is uniformly applied to both sides of a 20 μm-thick strip-shaped aluminum foil serving as a positive electrode current collector, and dried. At this time, a current collector exposed portion having a width of 5 mm to which the positive electrode mixture slurry is not applied is provided at an end in the width direction of the strip-shaped aluminum foil. From this state, the aluminum foil coated with the positive electrode mixture is compression-molded in the thickness direction. The dimensions of the positive electrode 1 are 290 mm in width and 340 in length.
0 mm, and the thickness of the coated portion of the positive electrode mixture was 200 μm. Next, an aluminum positive electrode current collecting lead 1 'having a thickness of 60 μm and a width of 5 mm is connected to the exposed portion of the current collector by ultrasonic welding. Forty positive electrode current collecting leads 1 ′ were connected to the positive electrode 1. The connection positioning of the forty positive electrode current collecting leads 1 ′ has two current collecting lead groups 11 as shown in FIG. 2 after a later-described winding step, and as a result, they sandwich the wound center. Care was taken to face each other.

(Preparation of Negative Electrode A) The negative electrode A was prepared as follows. Spherical mesocarbon microbeads (particle size 1
５０50 μm, d ₀₀₂ = 3.366 Å) 90 parts by weight of powder and 10 parts by weight of polyvinylidene fluoride were N-
A negative electrode mixture slurry is prepared by dispersing in a methylpyrrolidone solvent. The negative electrode mixture slurry is uniformly applied to both sides of a 20 μm-thick strip-shaped copper foil serving as a negative electrode current collector, and dried. At this time, a current collector exposed portion having a width of 30 mm to which the positive electrode mixture slurry is not applied is provided at an end portion in the width direction of the strip-shaped copper foil. From that state, the copper foil coated with the negative electrode mixture is compression-molded in the thickness direction. The dimensions of the negative electrode 2 are 290 mm in width, 3600 mm in length, and 120 μm in thickness of the negative electrode mixture applied portion. Next, the exposed portion of the current collector was punched out to obtain a 50 m
Strip leads having a width of 10 mm were formed at intervals of m.

(Preparation of Battery A) Positive electrode A and negative electrode A described above
Is wound through a polyethylene microporous film separator 3 having a thickness of 25 μm and a width of 280 mm to obtain a wound electrode group 8. The positive electrode current collecting lead 1 'in this state forms the current collecting lead group 11 in a state in which a plurality of positive electrode current collecting leads 1' are substantially stacked as shown in FIG. The two current collecting leads 11 are located to face each other with the center of the winding therebetween. The wound electrode group 8 is accommodated in a cylindrical stainless steel battery container 4 (diameter 48 mm, length 300 mm) by bending the negative electrode current collecting lead 2 ′ toward the center of the wound electrode group 8. Then, all of the negative electrode current collecting leads 2 'are located at the center of the winding. In this way, the negative electrode current collecting lead 2 '
And the bottom surface of the battery container 4 by welding can be connected. In other words, a rod-shaped welding electrode is inserted from the upper part of the winding center into the cylindrical space at the center of the winding, brought into contact with the negative electrode current collecting lead 2 ′, and another welding electrode is brought into contact with the bottom surface of the outer surface of the battery container 4 to conduct electricity. By doing so, the welding is realized. The battery container 4 also serves as a negative electrode external terminal. The positive electrode current collecting lead 1 ′ exists as the above-described current collecting lead group 11 (FIG. 2). In the current collecting lead group 11, the external terminals 5 (made of aluminum) of the portion to which the current collecting lead group 11 is connected have an integral multiple (2) of the number (2) of the current collecting lead group 11.
), That is, the external terminal 5 which is a quadrangular prism. The connection state is such that the current collecting lead group 11 and the flat portion of the side surface of the quadrangular prism are welded and the current collecting lead is not substantially curved, or is curved only in the length direction without substantially twisting. To do. The external terminal 5 is integrated with a battery lid 7 made of stainless steel and an insulating packing 6 made of polypropylene. The end of the battery cover 7 and the opening of the battery container 4 are fitted, and the fitted portion is connected by YAG laser welding. Then, a solution prepared by dissolving 1 mol / l lithium hexafluorophosphate in a mixed solvent of ethylene carbonate and dimethyl carbonate (1: 1 volume ratio) was injected as an electrolytic solution from an inlet provided in the battery cover 7 in advance. Then, the liquid inlet is sealed to seal the battery.

FIG. 3 shows another embodiment of the present invention, in which a positive electrode active material is a transition metal composite oxide containing lithium, in which a wound electrode group 8 is built in a battery case 4, and a negative electrode active material is provided. Is a carbon material capable of inserting and removing lithium ions, the charge-discharge reaction participating material is lithium for both the positive electrode active material and the negative electrode active material, and the electrolyte is a non-aqueous electrolyte. It is the figure which showed the principal part cross section. A method for producing the cylindrical wound battery will be described in detail.

(Preparation of Positive Electrode B) The number of the positive electrode current collecting leads 1 ′ was set to 48, and the number of the current collecting lead groups 11 in the case of the wound electrode group 8 was increased by 16 for each of the positive electrode current collecting leads 1 ′. Considering the position of the positive current collecting lead 1 ′ in the positive electrode 1 so that the adjacent current collecting lead groups 11 are located at 120 ° from the center of the winding, that is, as shown in FIG. Otherwise, a positive electrode B is produced under the same conditions as the positive electrode A.

(Preparation of Negative Electrode B) At the time of punching, consideration is given to forming the current collecting lead group 11 when the wound electrode group 8 is formed. To be more specific, the number of the current collecting lead groups 11 is set to three, each including 16 current collecting leads, and the adjacent current collecting lead groups 11 are respectively positioned at 120 ° from the winding center, that is, as shown in FIG. Consider the position of the current collecting lead so that it exists. Other than that, it is manufactured under the same conditions as the negative electrode A.

(Preparation of Battery B) Positive electrode B and negative electrode B described above
Is wound through a polyethylene microporous film separator 3 having a thickness of 25 μm and a width of 280 mm to obtain a wound electrode group 8. The state of the positive electrode current collecting lead 1 'in this state is shown in FIG.
As shown in the top view of FIG.
They exist at positions 120 ° from the winding center, respectively, as shown in FIG. The positive / negative current collecting leads exist as the current collecting lead group 11 (FIG. 4) as described above. The connecting portion of the current collecting lead group 11 to the external terminal 5 having a hexagonal column shape and a connection portion with the current collecting lead group 11 that is an integral multiple (twice) of the number (three) of the current collecting lead group 11 is used. However, as shown in FIG. 4, the current collecting lead group 11 is connected to a flat portion on the side surface of a hexagonal prism.
The current collecting lead group 1 is adjusted so as not to be substantially curved or to be curved only in the lengthwise direction without substantially twisting.
1 and the side surface of the external terminal 5 are connected by ultrasonic welding. Positive
In order to realize a connection state between the negative electrode current collecting lead and the external terminal 5 as shown in FIG. 3, a cylindrical body is used for the battery container 4 instead of the bottomed cylindrical body shown in FIG. Then, a member in which the external terminal 5 and the battery lid 7 are integrated via the insulating packing 6 is fitted into both of the cylindrical body openings. Other than that, it is manufactured under the same conditions as the battery A.

Although the above-mentioned batteries A and B are exemplified by lithium ion batteries, the present invention is not limited to battery systems. As the current collector used in the present invention, a metal having a thickness of 10 to 50 μm can be suitably used. The shape may be a sheet (foil, film, plate, etc.), mesh, lath, or the like. Nickel, aluminum, copper, and steel plated with these can be used as the material.

When the present invention is applied to a lithium ion battery as in this example, the positive electrode active material and the negative electrode active material can be appropriately changed. As the positive electrode active material, an interlayer compound such as lithium cobalt oxide or lithium nickel oxide as in this example, or a material partially substituted by another element of these active material elements can be used. As the negative electrode active material, a metal chalcogenide or the like capable of electrochemically inserting and removing lithium can be used in addition to a carbon material (including graphite).
However, when lithium manganate, which is lower in cost than lithium cobaltate, is used as the positive electrode active material of a wound nonaqueous electrolyte battery such as a lithium ion battery, the present invention is considered to be particularly effective. (Including materials partially replaced by elements). The reason is that lithium manganate is generally lower in electron conductivity than lithium cobaltate, lithium nickelate, or the like, and is expected to improve the conductivity (including current collection) of an electrode containing the same. That's why. In the battery A, the current collecting structure according to the present invention is used only for the positive electrode, and in the battery B, the current collecting structure according to the present invention is used for the positive and negative electrodes. However, the current collecting structure according to the present invention may be used only for the negative electrode. Battery A
Although the number of the current collecting lead groups 11 is two and the number of the current collecting lead groups 11 is three in the battery B, it may be four or more. However, when the number of the current collecting lead groups 11 increases, a lot of time is required for assembling the battery, which leads to an increase in cost. Furthermore, since the number of connection points by means such as welding between the current collecting lead group 11 and the external terminal 5 increases, there is a disadvantage that the reliability of the product is reduced. Therefore, the number of the current collecting lead groups 11 is appropriately 2 to 6 even when considered in conjunction with the results of the current collecting evaluation test and the like described later.

In the battery A, the two battery collection leads 11 are arranged so that the two current collecting lead groups 11 face each other across the center of the winding.
In FIG. 4, the three current collecting lead groups 11 are arranged at positions 120 ° from the winding center (positions at equal angles from the winding center) as shown in FIG. The arrangement is not particularly limited. However, current collecting lead group 11
Considering the good workability when connecting to the external terminal 5 and the ease of making the distribution of the current taken out of the electrode uniform,
When the current collecting lead group 11 has two places,
It is preferable that they are located facing each other across the center of the winding, and when there are three to six current collecting lead groups 11, they are preferably in directions substantially equiangular from the center of the winding. In the configuration of the batteries A and B, the side surface of the external terminal 5 at the portion to which the current collecting lead group 11 is connected is flat, and the current collecting lead is not substantially curved or substantially connected in the connected state. Although it is made to bend only in the length direction without causing torsion, the present invention is not limited to this. However, this is a preferable configuration because the external terminal 5 and the surface of the current collecting lead group 11 can be in contact with and connected to each other without excessive stress being applied to the current collecting lead.

[0020]

EXAMPLE Regarding the battery A (Example 1) described above, the number of the current collecting lead groups 11 was changed from 1 to 2 (Comparative Example 1), to 3 (Example 2), to 4 Batteries (Example 3), five batteries (Example 4), six batteries (Example 5), seven batteries (Comparative Example 2),
The following test was performed on eight batteries (Comparative Example 3). Here, the current collecting lead groups 11 adjacent to the batteries of Examples 2 to 5 and Comparative Examples 2 and 3 were respectively arranged at equal angles from the center of the winding. The number of current collecting leads was the same for each battery. The connection between the current collecting lead group 11 and the external terminal 5 is as follows.
The shape of the external terminal 5 at the portion to which the current collecting lead is connected is a prism having twice the number of the current collecting lead group 11, and the current collecting lead group 11 is connected to the flat portion on the side surface of the prism. Each current collecting lead was substantially non-curved or curved only in the longitudinal direction without substantially twisting. The current collecting lead group of the battery of Comparative Example 1 was 4
Each of the current collecting leads was connected to the external terminal of the prism, and in that connection state, each of the current collecting leads was substantially not bent, or was bent only in the length direction without substantially twisting.

(Test 1) Each battery was 7 A and the terminal voltage was 4.1.
After charging the battery to V, the battery was discharged at room temperature to 2.8 V at 7 A, and the electric capacity obtained was 35 Ah. Then, after charging under the same conditions, the capacity retention rate (value for 35 Ah) and the battery surface temperature at the end of the discharge when a high-rate discharge test was performed at 105 A (corresponding to 3 C) to discharge to a terminal voltage of 2.8 V at room temperature, and Was measured. Furthermore, after charging under the same conditions as above, discharging at 7A for 3.5 hours to a state of a discharge depth of 70%, and then measuring the average discharge voltage and output density when discharging at 245A (corresponding to 7C) for 30 seconds. did. Table 1 shows the measurement results. DOD in the table is an abbreviation for Depth Of Discharge.

[0022]

[Table 1]

From Table 1, the capacity retention ratio of the batteries of Examples 1 to 5 was 90% or more even under a high rate discharge of 3C discharge.
The battery of Comparative Example 1 having one current collecting lead group (capacity maintenance rate 7
8%). Example 5
It can also be seen that in Comparative Examples 2 and 3, in which the number of current collecting lead groups was increased, the capacity retention ratio was not different from that of the battery of Example 5. With respect to the battery surface temperature at the end of discharging, Examples 1 to 5 of the present invention were also applied.
In the battery of No. 5, since the current collecting property from the electrodes was good, the Joule heat was able to be suppressed and the temperature was low as compared with the battery of Comparative Example 1 in which the number of the current collecting leads was one. Recognize. It can also be seen that Comparative Examples 2 and 3, in which the number of current collecting lead groups was increased compared to Example 5, had approximately the same current collecting performance as the battery of Example 5. Regarding the average discharge voltage and the output density after 30 seconds of 7C discharge, the batteries of Examples 1 to 5 obtained much better results than the battery of Comparative Example 1 having one current collecting lead group. In Comparative Examples 2 and 3 in which the number of current collecting lead groups was increased compared to Example 5, the results were almost the same as those of the battery of Example 5. Such test results show that when the number of the current collecting lead groups 11 is increased as described above, the number of connection points by means such as welding between the current collecting lead groups 11 and the external terminals 5 increases, and the product reliability. Example 1 is disadvantageous in that
It was found that 2 to 6 is appropriate for the number of the current collecting lead groups 11 as shown in FIGS. This tendency was substantially the same for the battery B described in the embodiment of the invention.

(Test 2) Regarding the battery B described in the embodiment of the invention, the current collecting lead group 11 of the positive electrode 1 and the external terminal 5
Focusing on the welding process, the following test was conducted. Battery B
In the welding process between the current collecting lead group 11 of the positive electrode 1 and the external terminal 5, one surface of the hexagonal prism, which is the side surface of the external terminal 5, is fixed on the anvil as shown in FIG. On another surface, 16 aluminum foils (collection lead group 11 of the positive electrode 1) having a thickness of 60 μm are stacked and placed, and a pressing force is applied from above with a horn in the thickness direction of the current collection lead group 11 of the positive electrode 1. Welding is realized by applying ultrasonic vibration in parallel with the thickness direction of the current collecting lead group 11 of the positive electrode 1 while applying. Here, assuming that the number of the current collecting lead groups 11 of the positive electrode 1 was one, the superconducting conditions were the same as above except that 48 aluminum foils having a thickness of 60 μm (the current collecting lead group 11 of the positive electrode 1) were laminated. The energy required for welding when performing sonic welding was measured. Table 2 shows a comparison with the case of the present invention in which 16 current collecting lead groups 11 of the positive electrode 1 are stacked.

[0025]

[Table 2]

From the above results, when ultrasonically welding the 48 current collecting leads to the external terminal 5, the current collecting leads are divided into three 16-pieces each, compared to the case where 48 current collecting leads are stacked and welded. It can be seen that the welding energy (J) required by the welding machine is reduced by about half (to 75 J) when the welding is performed. Also, the peak power (W) required by the welding machine in one welding is better when the current collecting leads are divided into three 16 times and welded three times than in the case where 48 current collecting leads are stacked and welded. It can be seen that the time is less than half. Therefore, it can be understood that the welding machine to be used can have a smaller output and be smaller in size when welding is performed by dividing the current collecting leads into three 16 times, rather than by laminating and welding 48 current collecting leads. Therefore, it is possible to reduce the manufacturing cost by manufacturing the battery with three current collecting lead groups 11 each including the same number of current collecting leads, rather than manufacturing the battery with one current collecting lead group 11. I understand. This reduction in manufacturing cost is an approximation in the scope of the present invention other than the present test, and the energy required for welding can be reduced by 30 to 50%, and the equipment cost of the welding machine due to downsizing of the welding machine is 20 to 30%.
Can be reduced. The current collecting lead group 11 having undergone the above welding process.
As a result, when 48 current collecting leads were laminated and welded, there were portions where the welding strength was weak. This was particularly observed in the welding of the current collecting leads in the current collecting lead group 11 in FIG. 5 which were far from the external terminal 5 and the horn. On the other hand, when 16 current collecting leads were laminated and welded, sufficient welding strength could be obtained at all locations.

Further, as in this test, the shape of the external terminal 5 at the portion to which the current collecting lead is connected is 2
Each of the current collecting lead groups 11 is a double prism (a hexagonal prism).
Are arranged substantially in a straight line in the vertical direction of the prism and the battery in the longitudinal direction, and in this case, a welding process as shown in FIG. When the other current collecting lead group 11 is
Does not exist in the range of the width in which the pressing force is applied. Therefore, there is also an advantage that the battery can be easily manufactured because the other current collecting lead group 11 does not disturb the welding process. The above advantage is that the shape of the external terminal 5 at a portion to which the current collecting lead is connected is an integral multiple prism of one or more times the number of the current collecting lead group 11, and each current collecting lead group 11 is formed of a prismatic plane and a battery vertical. This is a common advantage when they are substantially linear in the direction.

[0028]

According to the present invention, in a wound type battery comprising a wound electrode group using a metal foil current collector, multi-current collection from the current collector is realized with high reliability, and high-rate discharge is achieved. The characteristics could be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a wound battery showing an example of the present invention.

FIG. 2 is a perspective view showing a wound electrode group and a positive electrode current collecting lead group of a wound type battery showing an example of the present invention.

FIG. 3 is a longitudinal sectional view of a main part of a wound battery showing another example of the present invention.

FIG. 4 is a diagram showing an arrangement of a current collecting lead group and external terminals in a wound electrode group according to the present invention.

FIG. 5 is a diagram showing a state in which a current collecting lead group is connected to external terminals by ultrasonic welding.

[Explanation of symbols]

 1. Positive electrode 1 '. 1. Positive electrode current collecting lead Negative electrode 2 '. 2. negative electrode current collecting lead Separator 4. Battery container 5. External terminal 6. Insulation packing 7. Battery cover 8. Wound electrode group 11. Current collecting lead group

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 10/40 H01M 10/40 Z (72) Inventor Mikio Oguma 2-8-7 Nihonbashi Honcho, Chuo-ku, Tokyo Shin-Kobe Electric Co., Ltd. Inside

Claims (6)

[Claims] 1. A wound battery comprising a group of electrodes in which a positive electrode and a negative electrode each having an active material disposed on the surface of a metal foil current collector are spirally wound with a separator interposed therebetween, wherein the electrode group has a winding direction. It has two to six current collecting lead groups each including a plurality of current collecting leads of the same polarity derived from the electrode ends in the orthogonal direction, and the current collecting lead group is connected to an external terminal. A wound battery. 2. The wound battery according to claim 1, wherein the current collecting leads are formed in a state where the current collecting leads are stacked. 3. A side face of an external terminal at a portion to which the current collecting lead group is connected is flat, and in the connected state, each current collecting lead is not substantially curved or substantially twisted. The wound battery according to claim 1, wherein the battery is curved only in the length direction. 4. The current collecting lead group which is adjacent to the winding center is substantially at an equal angle from the winding center.
The wound type battery according to any one of the above. 5. An external terminal at a portion to which a current collecting lead is connected is a prism having an integral multiple of one or more of the number of current collecting leads.
The current collecting lead group is connected to a flat portion on the side surface of the prism,
The winding type according to claim 3, wherein, in the connection state, each of the current collecting leads is substantially not curved, or is curved only in the length direction without substantially twisting. battery. 6. The positive electrode active material is a transition metal composite oxide containing lithium, the negative electrode active material is a carbon material capable of inserting and removing lithium ions, and the charge / discharge reaction participating material is a positive electrode active material and a negative electrode active material. The wound battery according to any one of claims 1 to 4, wherein the substance is lithium and the electrolyte is a non-aqueous electrolyte.