JPH1173995A - Cylindrical nonaqueous electrolyte solution secondary battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically reduce the internal resistance of a battery, even if for a large battery, and enhance its productivity. SOLUTION: Circular current delivery parts integrally formed with a positive electrode current collector 7 and protrusively formed from the end of separators are disposed in every winding circuit so as to provide aside in a radial direction of a volute electrode body, and the current delivery parts are overlapped with each other and fused, whereby a delivery terminal 6 is flush with at least one surface is formed, and moreover an upper end surface 6a whose surface is flushed with the delivery terminal 6 and a current terminal 7 are fused, and both the surfaces are welded with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical non-aqueous electrolyte secondary battery and a method of manufacturing the same, and more particularly to a cylindrical non-aqueous electrolyte secondary battery used in electric vehicles and the like, which requires a high output density. And its manufacturing method.

[0002]

2. Description of the Related Art A battery of this type has a spiral electrode body in which a belt-like positive electrode and a negative electrode are spirally wound with a separator interposed therebetween. This has been done by attaching conductive tabs to the ends of the positive and negative electrodes, respectively, and electrically connecting these conductive tabs to current terminals. In a battery having such a structure, a small cylindrical non-aqueous electrolyte secondary battery having a small current value can sufficiently exhibit a current collecting effect, but a large cylindrical non-aqueous electrolyte having a large current value. The electrolyte secondary battery has a problem that the current collecting effect cannot be sufficiently exhibited because the electrode area is large.

Therefore, a cylindrical non-aqueous electrolyte secondary battery provided with the following current collecting method has been proposed. As shown in JP-A-6-267528, at both ends in the longitudinal direction of a current collector of a band-shaped positive electrode and a band-shaped negative electrode,
A positive electrode lead mounting portion and a negative electrode lead mounting portion protruding from the separator are formed, and these two lead mounting portions have a cylindrical non-aqueous structure in which a plurality of positive electrode leads and a plurality of negative electrode leads are welded. Electrolyte secondary battery.

As shown in Japanese Patent Application Laid-Open No. HEI 8-115744, an exposed portion of a positive electrode current collector projecting from a separator and a negative electrode An exposed portion of the current collector is formed, and the exposed portion of the positive electrode current collector is connected by a positive electrode lead,
The exposed portion of the negative electrode current collector is connected by a negative electrode lead,
A cylindrical non-aqueous electrolyte secondary battery having a structure in which a positive electrode lead and a negative electrode lead are connected to a current terminal via a connecting member or directly.

[0005]

However, the conventional cylindrical non-aqueous electrolyte secondary battery has the following problems. In the above battery, since the positive electrode lead and the positive electrode lead mounting portion and the negative electrode lead and the negative electrode lead mounting portion are connected by welding, contact resistance occurs at the connection portion, The internal resistance of the battery cannot be reduced dramatically. In addition, since it is difficult to connect each of the plurality of positive leads and the plurality of negative leads to the current terminal, there is a problem that productivity is reduced.

In the above battery, it is difficult to uniformly connect the positive electrode lead and the negative electrode lead made of metal foil to the exposed portions of the positive and negative electrode current collectors. Furthermore, since the connection surface formed by each lead and each current collector is not planar, when welding the connection member or the current terminal to the connection surface by a laser method or the like, a point-like welding is performed. As a result, the contact area between them becomes small. from these things,
There was a problem that productivity was poor and the internal resistance of the battery could not be reduced dramatically.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned conventional problems, and it is possible to drastically reduce the internal resistance of a large battery and increase productivity. An object of the present invention is to provide a cylindrical non-aqueous electrolyte secondary battery that can be manufactured and a method for manufacturing the same.

[0008]

Means for Solving the Problems To achieve the above object, a cylindrical nonaqueous electrolyte secondary battery of the present invention comprises a positive electrode having a positive electrode active material layer formed on both sides of a belt-shaped positive electrode current collector. A negative electrode in which a negative electrode active material layer is formed on both sides of a strip-shaped negative electrode current collector, and a spiral electrode body that is spirally wound via a strip-shaped separator, wherein the positive electrode and the negative electrode are directly Alternatively, in a cylindrical nonaqueous electrolyte secondary battery having a structure electrically connected to a current terminal via a lead wire, the cylindrical nonaqueous electrolyte secondary battery is integrated with at least one of the positive electrode current collector and the negative electrode current collector. Arc-shaped current extracting portions formed in a manner to project from the end of the separator are provided in each turn so as to be juxtaposed in the radial direction of the spiral electrode body, and the current extracting portions are further provided. At least one surface by overlapping and welding Lead terminal to be flush is formed, moreover, with the above flush become extracting surface of the lead terminal and the current terminal or the lead wires is characterized in that-joined by welding.

With the above configuration, the extraction terminal and the positive electrode current collector and / or the negative electrode current collector, which are formed by overlapping and welding the current extraction portions, are integrally formed, and the extraction terminal and the current The connection with the terminal or the lead wire is a surface connection. Therefore, the contact resistance between the positive electrode current collector and / or the negative electrode current collector and the current terminal is greatly reduced, and the internal resistance of the battery is significantly reduced. In addition, a current extraction portion is formed for each round, and the extraction terminal formed by the current extraction portion is electrically connected to the current terminal, so that the potential gradient in the current collector is small and the current distribution is biased. There is no.

According to a second aspect of the present invention, there is provided the cylindrical non-aqueous electrolyte secondary battery according to the first aspect, wherein a current extracting portion on the positive electrode side integrally formed with the positive electrode current collector; And a current extracting portion on the negative electrode side integrally formed, and one current extracting portion is formed so as to protrude to the opposite side to the other current extracting portion. As described above, if one of the current extracting portions is formed so as to protrude on the opposite side to the other current extracting portion, a short circuit inside the battery can be prevented.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
In the cylindrical nonaqueous electrolyte secondary battery described above, the ratio of the arc length of the current extracting portion to the circumferential length in each round of the spiral electrode body is 5% or more. When the ratio of the arc length of the current extracting portion to the circumferential length in each revolution of the spiral electrode body is less than 5%, the discharge capacity sharply decreases. However, when the ratio of the arc length of the current extracting portion is 5% or more. If so, no difference in discharge capacity is recognized.

According to a fourth aspect of the present invention, in the cylindrical non-aqueous electrolyte secondary battery according to the third aspect, a plurality of extraction terminals are formed. If a plurality of extraction terminals are formed in this manner, the ratio of the arc length of the current extraction portion to the circumferential length in each round of the spiral electrode body can be easily set to 5% or more.

In order to achieve the above object, a method of manufacturing a cylindrical nonaqueous electrolyte secondary battery according to the present invention comprises: a positive electrode having a positive electrode active material layer formed on both sides of a belt-shaped positive electrode current collector; Of the negative electrode in which the negative electrode active material layer is formed on both surfaces of the strip-shaped negative electrode current collector, an exposed portion where the active material layer is not formed on the current collector in at least one of the electrodes is formed, and the exposed portion is formed in a strip shape. A first step of spirally winding both electrodes through the separator so as to protrude from the end of the separator, and cutting the exposed portion while leaving a part of the exposed portion of the current collector; A second step in which arc-shaped current extraction portions are provided in each revolution so as to be arranged in parallel in the radial direction of the spiral electrode body, and at least one surface is formed by overlapping and welding the current extraction portions. A third step of forming a single extraction terminal; And having a fourth step of surface joined by welding and the lead surface and the current terminal or said lead wire to be the surface one lead terminal.

According to the above-described method, since the extraction terminal can be formed only by processing the exposed portion, the productivity of the battery is improved. In addition, since only the exposed portion for forming the extraction terminal remains (that is, most of the exposed portion is cut), the weight increase of the battery is minimized, and the weight energy density of the battery is improved.

According to a sixth aspect of the present invention, in the method for manufacturing a cylindrical nonaqueous electrolyte secondary battery according to the fifth aspect, the welding in the third step is performed by a non-contact welding method. When the welding is performed by the non-contact welding method as described above, it is possible to prevent a thin, low-strength current extracting portion from being deformed when the extracting terminal is manufactured.

According to a seventh aspect of the present invention, in the method for manufacturing a cylindrical nonaqueous electrolyte secondary battery according to the sixth aspect, the non-contact welding method is a laser welding method. Thus, if the laser welding method is used as the non-contact welding method,
Since there is no need to perform welding in a vacuum state unlike the beam welding method, workability is improved. In addition, since the welding depth is large, the welding strength can be improved.

According to an eighth aspect of the present invention, in the method for manufacturing a cylindrical non-aqueous electrolyte secondary battery according to the fifth aspect, the connection between the extraction terminal and the current terminal or the extraction terminal and the lead wire in the fourth step is performed. Is performed by a welding method selected from the group consisting of an ultrasonic welding method, a beam welding method, and a laser welding method.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, as shown in FIG. 1, on both sides of a strip-shaped positive electrode current collector 1a (thickness: 0.02 mm) made of aluminum, a positive electrode active material made of LiCoO ₂ , a conductive additive made of carbon, and polyvinylidene fluoride ( A positive electrode 1 in which a positive electrode active material layer 1b is formed on both surfaces of a positive electrode current collector 1a is produced by applying a positive electrode mixture mixed with a binder made of PVdF). At this time, an uncoated portion 1c in which the positive electrode active material layer 1b does not exist is formed at one end in the longitudinal direction of the positive electrode current collector 1a.

In parallel with this, as shown in FIG. 2, a strip-shaped negative electrode current collector 2a (thickness: 0.018 mm) made of copper
A negative electrode 2 in which a negative electrode active material layer 2b is formed on both surfaces of a negative electrode current collector 2a is prepared by applying a negative electrode mixture obtained by mixing a negative electrode active material composed of natural graphite and a binder composed of PVdF to both surfaces of the negative electrode current collector 2a. I do. At this time, the negative electrode current collector 2a
At the other end in the longitudinal direction (the end in the direction opposite to the positive electrode 1), the uncoated portion 2c where the negative electrode active material layer 2b does not exist
To form Next, as shown in FIG. 3, the width L _3, to prepare a width L ₁ and the separator 3 formed to be slightly larger than the width L ₂ of the negative electrode active material layer 2b of the positive electrode active material layer 1b . The separator 3 is made of porous polyethylene or polypropylene.

Next, as shown in FIG. 4 and FIG. 5, the positive electrode 1, the negative electrode 2, and the separator 3 are overlapped, and these are spirally wound to form a spiral electrode body 4 as shown in FIG. I do. At this time, the uncoated portion 1c on the positive electrode side,
The uncoated portion 2c on the negative electrode side (in FIG. 6, the uncoated portion 2c
(Not shown) are formed so as to protrude from the end of the separator 3. Thereafter, as shown in FIG. 6, while irradiating the laser light in parallel with the upper end surface of the spiral electrode body 4, the laser light is moved half a turn in the C1 direction, and further moved to the upper end of the spiral electrode body 4 in the B1 direction. Then, the right half of the uncoated portion 1c is cut off. Thereafter, while irradiating the laser light in parallel with the upper end surface of the spiral electrode body 4, the laser light is moved half a turn in the C2 direction, and further moved in the B2 direction to the upper end of the spiral electrode body 4, and the uncoated portion 1c Cut out the left half of the. As a result, as shown in FIG. 7, arc-shaped current extraction portions 5 projecting from the end of the separator 3 are arranged in parallel with each other and in the radial direction of the spiral electrode body 4. Become. In FIG. 7 and FIG. 8 described later, only the positive electrode current collector 1a of the spiral electrode body 4 is shown for easy understanding, and the negative electrode 2, the separator 3, and the like are omitted.

Thereafter, as shown in FIG.
Are overlapped and welded by a laser beam to form a positive electrode-side extraction terminal 6 having at least one surface (the upper end surface 6a in this example) flush with the surface. Although not shown, the same processing is performed on the uncoated portion 2c on the negative electrode side. Finally, as shown in FIG. 9, the upper end surface 6a (current extraction surface) of the extraction terminal 6 on the positive electrode side and the positive electrode current terminal 7 made of aluminum are welded by a laser, and the two are surface-bonded. The lower end surface 8a (current extraction surface) of the extraction terminal 8 and the negative electrode current terminal 9 made of copper were welded by a laser, and the two were surface-joined.

Here, in order to take out the current smoothly,
It is desirable that the ratio of the arc length of the current extracting portions 5 to the circumferential length in each round of the spiral electrode body 4 be 5% or more. However, in the case where the diameter of the spiral electrode body 4 is extremely large, the arc lengths of the current extracting portions 5 at the center portion and the outer peripheral portion of the spiral electrode body 4 are set to be the same as in the embodiment of the present invention. Then, in the outer peripheral portion having a large circumferential length, the ratio of the arc length becomes 5% or less. Therefore, in such a case, as shown in FIG. 10, a structure in which the arc length of the current extraction portions 5 is increased from the center to the outer periphery of the spiral electrode body 4, or FIG. As shown in FIG. 11, the structure may be such that two or more of the positive electrode side extraction terminal 6 and the negative electrode side extraction terminal 8 are formed.

In the embodiment of the present invention, the extraction terminals 6 and 8 having at least one surface flush with each other are formed by the laser welding method. However, such extraction terminals 6 and 8 are formed by the beam welding method. 8 may be formed. However, in the beam welding method, work must be performed in a vacuum state, so that workability is reduced. In addition, since the welding depth of the beam welding method is smaller than that of the laser welding method, the welding strength is reduced. Therefore, take out terminal 6
When forming 8, it is desirable to use a laser welding method. When these welding methods are used, the upper end face 6
It is necessary to appropriately determine the area between “a” and the lower end surface 8 a (both are current extraction surfaces) according to the maximum current value determined from the battery capacity.

Further, the upper end surface 6a of the positive side extraction terminal 6 and the positive electrode current terminal 7 and the upper surface 8a of the negative electrode side extraction terminal 8 and the negative surface current terminal 9 are bonded by laser welding. Although it is performed, it may be performed using a beam welding method or an ultrasonic welding method. However, the beam welding method has a problem that the workability is reduced as described above, and the ultrasonic welding method has a problem that both the extraction terminals 6 and 8 may be damaged by pressure. It is desirable to join the two. In addition, in the embodiment of the present invention, both the takeout terminals 6 and 8 and the both current terminals 7 and 9 are directly joined, respectively. However, the present invention is not limited to such a structure. So that the positive lead 1
A structure may be employed in which both the takeout terminals 6 and 8 and the two current terminals 7.9 are electrically connected via the first and negative lead wires 10. In this case, the extraction terminal 6 on the positive electrode side and the positive electrode lead wire 11 and the extraction terminal 8 on the negative electrode side and the negative electrode lead wire 10 are surface-bonded.

As the positive electrode active material, the above-described LiC
It is not limited to oO ₂ , but LiNiO ₂ , LiM
n ₂ O ₄ or the like can be used, and the negative electrode active material is not limited to the above-mentioned natural graphite, and other carbon materials such as artificial graphite can be used. In addition, the positive electrode lead wire 11 is not limited to the above-described aluminum, but may be iron, stainless steel, nickel, or the like. The negative electrode lead wire 10 is not limited to the above-described copper. , Iron, stainless steel, nickel and the like can be used.

[0026]

【Example】

[Example] As an example, the cylindrical nonaqueous electrolyte secondary battery described in the above embodiment of the present invention was used. The height of this battery was 400 mm, the diameter was 60 mm, the nominal capacity was 70 Ah, and the battery voltage was 3.6 V. The battery having such a structure is hereinafter referred to as Battery A of the present invention.

[Comparative Example] As a comparative example, a cylindrical non-aqueous electrolyte secondary battery (Japanese Patent Laid-Open No. Hei 6-26
No. 7528). The battery height and the like were formed in the same manner as in the above example. A battery having such a structure is hereinafter referred to as a comparative battery X.

[Experiment 1] Battery A of the present invention and Comparative Battery X
The relationship between the discharge capacity and the battery voltage in the above was examined, and the results are shown in FIG. The charge and discharge conditions in this experiment were as follows: a constant current charge was performed at a current of 0.14 C (9.8 A) until the battery voltage reached 4.2 V;
The condition is that the battery is discharged at a constant current until the battery voltage becomes 2.7 V with the current A).

As is clear from FIG. 13, the discharge capacity of the comparative battery X is 62.3 Ah, whereas the discharge capacity of the battery A of the present invention is 68.9 Ah, and the capacity is significantly increased. Is admitted. This is because, in the battery A of the present invention, the current collector and the extraction terminal are integrally formed,
In addition, since the connection between the extraction terminal and the current terminal is a surface junction, the contact resistance between the current collector and the current terminal is greatly reduced, and the internal resistance of the battery is significantly reduced. Conceivable.

[Experiment 2] The relationship between the ratio of the arc length of the current extracting portion to the circumferential length of the spiral electrode body (hereinafter simply referred to as the ratio of the arc length of the current extracting portion) and the discharge capacity is examined. Therefore, the result is shown in FIG. As is clear from FIG. 14, the discharge capacity sharply decreases when the ratio of the arc length of the current extracting portion is less than 5%, but the discharge capacity decreases when the ratio of the arc length of the current extracting portion is 5% or more. No difference is observed. Therefore, it is desirable that the ratio of the arc length of the current extracting portion is 5% or more.

The result of such an experiment is that if the ratio of the arc length of the current extracting portion is less than 5%, the current collecting effect cannot be sufficiently exhibited, so that the internal resistance of the battery increases,
This is considered to be because the internal resistance of the battery does not decrease even if the ratio of the arc length of the current extracting portion is 5% or more, even if the ratio is increased.

[0032]

According to the present invention as described above,
Since the internal resistance of the battery is significantly reduced, the discharge capacity of the battery can be dramatically increased. Further, since the extraction terminal can be formed only by processing the exposed portion, the productivity of the battery is improved, and only the exposed portion for forming the extracted terminal remains (that is, most of the exposed portion is cut off). Therefore, the weight increase of the battery is suppressed to the minimum, and an excellent effect of improving the weight energy density of the battery is exhibited.

[Brief description of the drawings]

FIG. 1 is a front view of a positive electrode used in the present invention.

FIG. 2 is a front view of a negative electrode used in the present invention.

FIG. 3 is a front view of a separator used in the present invention.

FIG. 4 is a front view when a positive electrode, a negative electrode, and a separator are overlapped.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a perspective view showing a manufacturing process of the battery.

FIG. 7 is a perspective view showing a manufacturing process of the battery.

FIG. 8 is a perspective view showing a battery manufacturing process.

FIG. 9 is a cross-sectional view showing a manufacturing process of the battery.

FIG. 10 is a perspective view showing a modification of the present invention.

FIG. 11 is a sectional view showing a modification of the present invention.

FIG. 12 is a sectional view showing a modification of the present invention.

FIG. 13 is a graph showing a relationship between a discharge capacity and a battery voltage in a battery A of the present invention and a comparative battery X.

FIG. 14 is a graph showing the relationship between the ratio of the arc length of the current extracting portion to the circumferential length of the spiral electrode body and the discharge capacity.

[Explanation of symbols]

 1: Positive electrode 1a: Positive electrode current collector 1b: Positive electrode active material layer 1c: Uncoated portion 2: Negative electrode 2a: Negative electrode current collector 2b: Negative electrode active material layer 2c: Uncoated portion 3: Separator 4: Spiral electrode body 5: Current extractor 6: Extract terminal 7: Positive current terminal 8: Extract terminal 9: Negative current terminal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ikuro Yonezu 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.

Claims (8)

[Claims] A positive electrode in which a positive electrode active material layer is formed on both sides of a belt-shaped positive electrode current collector and a negative electrode in which a negative electrode active material layer is formed on both sides of a band-shaped negative electrode current collector form a band-shaped separator. Cylindrical non-aqueous electrolyte secondary battery having a structure in which the positive electrode and the negative electrode are electrically connected to a current terminal directly or via a lead wire, comprising a spiral electrode body spirally wound through In the positive electrode current collector or the negative electrode current collector, the arc-shaped current extraction portion formed integrally with at least one of the current collectors and formed so as to protrude from an end of the separator is formed in the spiral shape. Provided for each revolution so as to be juxtaposed in the radial direction of the electrode body, and furthermore, by overlapping and welding the current extraction portions, an extraction terminal is formed in which at least one surface is flush, and The extraction surface that is flush with the extraction terminal Serial current terminal or cylindrical non-aqueous electrolyte secondary battery in which the lead line is characterized in that-joined by welding. 2. A positive electrode current extracting portion integrally formed with the positive electrode current collector, and a negative electrode current extracting portion formed integrally with the negative electrode current collector, and 2. The cylindrical non-aqueous electrolyte secondary battery according to claim 1, wherein the current extracting portion is formed so as to protrude on a side opposite to the other current extracting portion. 3. A method according to claim 1, wherein the ratio of the arc length of said current extraction portion to the circumference of each spiral of said spiral electrode body is 5%.
%. The cylindrical nonaqueous electrolyte secondary battery according to claim 1, wherein 4. The cylindrical non-aqueous electrolyte secondary battery according to claim 3, wherein a plurality of the extraction terminals are formed. 5. A positive electrode in which a positive electrode active material layer is formed on both sides of a belt-shaped positive electrode current collector, and a negative electrode in which a negative electrode active material layer is formed on both sides of a band-shaped negative electrode current collector. The current collector in the pole is formed with an exposed portion on which the active material layer is not formed, and the electrodes are spirally wound through the separator so that the exposed portion protrudes from an end of the strip-shaped separator. A first step of cutting the exposed portion while leaving a part of the exposed portion of the current collector, so that the arc-shaped current extracting portion is arranged in each turn so as to be arranged in the radial direction of the spiral electrode body. A third step of forming an extraction terminal in which at least one surface is flush with the current extraction portion by overlapping and welding the current extraction portion.
A cylindrical non-aqueous electrolyte secondary battery, comprising: a step; and welding the surface of the extraction terminal, which is flush with the extraction terminal, to the current terminal or the lead wire by surface welding. Manufacturing method. 6. The method for manufacturing a cylindrical nonaqueous electrolyte secondary battery according to claim 5, wherein the welding in the third step is performed by a non-contact welding method. 7. The method for manufacturing a cylindrical nonaqueous electrolyte secondary battery according to claim 6, wherein the non-contact welding method is a laser welding method. 8. The connection between the extraction terminal and the current terminal or the connection between the extraction terminal and the lead wire in the fourth step is selected from the group consisting of an ultrasonic welding method, a beam welding method, and a laser welding method. The method for producing a cylindrical nonaqueous electrolyte secondary battery according to claim 5, which is performed by a welding method.