JP2010086799A - Laminated battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated battery capable of suppressing deterioration of a cycle lifetime of the battery even when high-rate charge and discharge are carried out, by controlling the occurrence of variations in the connection resistance between an electrode plate and a current collector terminal. <P>SOLUTION: The laminated battery has a plurality of positive electrode plates and negative electrode plates alternately laminated through a separator, and the electrode tabs extended from each electrode plate are jointed respectively to the current collector terminal of the positive and negative electrodes laminated in a plurality of layers. A penetrated part 31A is formed in at least one of the electrode plate tabs 11, and a plurality of electrode plate tabs 11 are jointed through the penetrated part 31A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a laminated battery, and more particularly, to a laminated battery having a high capacity and a high rate characteristic used for a robot, an electric vehicle, a backup power source and the like.
More particularly, the present invention relates to a large-capacity lithium ion battery in which the connection resistance with each electrode plate is made uniform in a stacked battery that requires a large number of stacked sheets and a large number of electrode plate tabs connected to current collector terminals.

  In recent years, batteries have been used not only for power sources of mobile information terminals such as mobile phones, notebook personal computers, and PDAs, but also for robots, electric vehicles, backup power sources, etc., and further increase in capacity is required. It has become like this. In response to such demands, lithium ion secondary batteries have high energy density and high capacity, and are therefore widely used as drive power sources as described above.

  The battery form of such a lithium ion secondary battery is broadly divided into a spiral type in which an electrode body obtained by winding a positive and negative electrode plate through a separator is enclosed in an exterior body, and a laminate in which a plurality of rectangular electrodes are laminated. There is a laminated type in which an electrode body is enclosed in an exterior body.

  Among these lithium ion secondary batteries, the specific structure of the laminated electrode body of the latter battery is that a sheet-like positive electrode having a positive electrode lead and a sheet-like negative electrode having a negative electrode lead are substantially the same shape as the negative electrode. The required number of layers are stacked via a square separator. In addition, a plurality of electrode plate tabs extending from each electrode plate are stacked and overlapped so as to be joined to the positive and negative current collecting terminals by ultrasonic welding, respectively (see Patent Documents 1 and 2 below). .

JP 2008-66170 A JP 2008-91268 A

  Here, in the lithium ion secondary battery, the capacity has increased in recent years as described above, and accordingly, the number of positive and negative electrode plates tends to increase, and the battery has a high rate. Considering charging / discharging, the thickness of the positive and negative current collecting terminals tends to increase. For this reason, it is necessary to perform ultrasonic welding in a state where a large number of electrode plate tabs are stacked on a thick-walled current collecting terminal. Since it is joined, the weldability of the welded part has deteriorated. For this reason, there is a variation in the connection resistance value between the electrode plate and the current collector terminal. In particular, when charging / discharging at a high rate, the value of the current flowing through each electrode plate becomes non-uniform. That is, a large current flows at a portion where the connection resistance value between the electrode plate and the current collecting terminal is small, while a small current flows at a portion where the connection resistance value between the electrode plate and the current collecting terminal is large. As a result, the charge / discharge state is unevenly distributed in the battery, and as a result, there is a problem in that the battery is partially overdischarged or overcharged and the cycle life of the battery is reduced.

  Therefore, for example, by increasing the amount of energy applied by ultrasonic welding to increase the bonding strength, the welded portion can be welded even when the number of stacked electrode plates is increased or the thickness of the current collecting terminal is increased as described above. It is also conceivable that the connection resistance value between the electrode plate and the current collecting terminal is made uniform. However, the method of increasing the amount of energy applied by ultrasonic welding in this way is accompanied by the difficulty that the outermost electrode tab is particularly liable to break.

  Further, the electrode plate tab is laminated at a position (hereinafter also referred to as “middle position”) between the electrode plate tab and the electrode plate (hereinafter also referred to as “terminal connection portion”). Even if only a plurality of electrode tabs are joined and integrated, the uniformity of the connection resistance value can be improved, but this method also increases the number of electrode tabs in the welded part of only the electrode tabs. Welding uniformity is reduced.

  The present invention has been made in consideration of the above, and performs charging and discharging at a high rate by suppressing variations in the connection resistance value between the electrode plate and the current collecting terminal. Even if it is a case, it aims at providing the laminated battery which can suppress that the cycle life of a battery falls.

In order to achieve the above object, the laminated battery of the present invention is
A stacked battery in which a plurality of positive and negative electrode plates are alternately stacked via separators, and a plurality of electrode plate tabs extending from each electrode plate are stacked and bonded to positive and negative current collecting terminals, respectively. There,
A penetration part is formed in at least one electrode plate tab, and a plurality of electrode plate tabs are joined to each other through the penetration part.

  According to the above configuration, even when the number of stacked electrode plates is increased or the thickness of the current collecting terminal is increased, a penetration portion is formed at the junction portion of the electrode plate tabs, and a plurality of electrode plate tabs are connected to each other. Therefore, the number of electrode tabs to be joined is reduced. Therefore, it is possible to ensure sufficient bonding strength and make the connection resistance value between the electrode plate and the current collecting terminal uniform, and it is not necessary to increase the amount of energy applied by, for example, ultrasonic welding. Therefore, a situation such as breakage of the electrode plate tab is not caused.

  A plurality of sheets in which the penetrating part is formed at a position (medium position) between a joining part (terminal joining part) where the electrode plate tab is joined to a current collecting terminal and the electrode plate, and the laminated parts are formed at the penetrating part It is desirable that only the electrode plate tabs are joined and integrated.

  Even though the through portion is formed in the terminal joint portion, it is possible to secure the joint strength at the terminal joint portion and make the connection resistance value between the electrode plate and the current collecting terminal uniform, but the middle position In this case, only a thin plate tab having a thickness of several μm to several tens of μm per sheet is in a laminated state, so this middle position (especially particularly desirable is the center between the terminal joint and the plate). If a plurality of electrode plate tabs stacked through the through part are joined and integrated, the electrode plate tabs are joined and integrated more easily and reliably. The connection resistance value between the electrode plate and the current collecting terminal can be made uniform. In addition, since the electrode tabs are joined not only at the terminal joint portion but also at the middle position, the electrode tabs can be electrically connected more reliably.

It is desirable that the joining is performed by ultrasonic welding.
The effect of the present invention is exhibited even when the joining is performed by a method of mechanically joining the joining target member, such as a shearing, caulking, screwing, or the like that deforms the joining target member, In addition, there is an advantage that the joining work can be performed with simple equipment and the battery can be manufactured easily and inexpensively, but welding is preferable because the resistance can be made uniform.
Further, as a welding method, for example, a resistance welding method or a laser welding method can be used, but ultrasonic welding is particularly desirable in terms of welding strength and the like.

  According to the present invention, even when the number of stacked electrode plates is increased or the thickness of the current collecting terminal is increased, the connection resistance value between the electrode plate and the current collecting terminal is not sufficiently varied by ensuring sufficient bonding strength. Occurrence of the battery can be suppressed, and this provides an excellent effect that the cycle life of the battery can be suppressed from being lowered even when charging / discharging at a high rate.

  Hereinafter, the laminated battery according to the present invention will be described below. The laminated battery according to the present invention is not limited to those shown in the following embodiments, and can be implemented with appropriate modifications within a range not changing the gist thereof.

[Production of positive electrode]
90% by mass of LiCoO ₂ as a positive electrode active material, 5% by mass of carbon black as a conductive agent, 5% by mass of polyvinylidene fluoride as a binder, N-methyl-2-pyrrolidone as a solvent ( NMP) solution was mixed to prepare a positive electrode slurry, and this positive electrode slurry was applied to both surfaces of an aluminum foil (thickness: 15 μm) as a positive electrode current collector. Then, after drying the solvent and compressing to a thickness of 0.1 mm with a roller, as shown in FIG. 1, it was cut so that the width L1 = 95 mm and the height L2 = 115 mm, and the positive electrode active material layer on both sides A positive electrode plate 1 having 1a was produced. At this time, an active material uncoated portion having a width L3 = 30 mm and a height L4 = 20 mm was extended from one end portion (left end portion in the figure) of one short side of the positive electrode plate 1 to form a positive electrode tab 11.

(Production of negative electrode)
A negative electrode slurry was prepared by mixing 95% by mass of graphite powder as a negative electrode active material, 5% by mass of polyvinylidene fluoride as a binder, and an NMP solution as a solvent. It apply | coated to both surfaces of the copper foil (thickness: 10 micrometers) as a negative electrode collector. Then, after drying the solvent and compressing to a thickness of 0.08 mm with a roller, as shown in FIG. 2, it was cut so that the width L7 = 100 mm and the height L8 = 120 mm, and the negative electrode active material layer on both sides A negative electrode plate 2 having 2a was produced. At this time, an active portion having a width L9 = 30 mm and a height L10 = 20 mm from an end portion (right end portion in the drawing) opposite to the positive electrode tab 11 forming side end portion of the positive electrode plate 1 on one short side of the negative electrode plate 2. The material uncoated portion was extended to form a negative electrode tab 12.

[Perforation of positive and negative electrode tabs]
As shown in FIG. 4 (a), through portions 31A and 31A were drilled at two positions at intervals in the width direction in the middle position of the positive electrode tab 11 of the positive electrode plate 1, respectively. More specifically, each of the through portions 31A and 31A has a square shape with a width of 5 mm and a height of 5 mm, and the left side of the through portion 31A is a few mm from the edge of the positive electrode tab 11 on the positive electrode plate 1 side. The tab 11 is formed at positions of 0 mm and 15 mm from the outer edge (side edge continuous to one long edge of the positive electrode plate 1; left edge in the figure), respectively. The positive electrode plate 1 having the through-holes 31A and 31A thus drilled is also referred to as “A type positive electrode plate 1A” hereinafter.
Further, as shown in FIG. 4B, the through-holes 31A and 31A of the A-type positive electrode plate 1A are placed inward in the width direction (right side in the figure) at the middle position in the positive electrode tab 11 of another positive electrode plate 1. A through portion 31B having the same size and shape as the through portions 31A and 31A at a position 5 mm and 20 mm away from the outer end edge (left end edge in the figure) of the positive electrode tab 11, Each 31B was drilled. The positive electrode plate 1 having the through-holes 31B and 31B thus formed is hereinafter also referred to as “B type positive electrode plate 1B”.
Moreover, as shown in FIG.4 (c), both the penetration parts 31B and 31B of the said B type positive electrode plate 1B are made into the width direction inner side (right side on a figure) in the middle position in the positive electrode tab 11 of another positive electrode plate 1. FIG. The through-hole 31C having the same size and the same shape as the through-holes 31B and 31B at a position 10 mm and 25 mm away from the outer edge (left edge in the figure) of the positive electrode tab 11 , 31C were drilled. The positive electrode plate 1 having the through-holes 31C and 31C thus drilled is also referred to as “C-type positive electrode plate 1C” hereinafter.

On the other hand, as shown in FIG. 5 (a), at the middle position of the negative electrode tab 12 in the negative electrode plate 2, a position that is bilaterally symmetrical with the two through portions 31A and 31A of the A type positive electrode plate 1A, that is, the negative electrode tab 12 is provided. Penetrating portions having the same dimensions and the same shape as the penetrating portions 31A and 31A at positions of 0 mm and 15 mm, respectively, from the outer edge (the side edge continuous to one long edge of the negative electrode plate 2; the right edge in the figure). Portions 32A and 32A were drilled, respectively. The negative electrode plate 2 in which the through portions 32A and 32A are thus drilled is hereinafter also referred to as “A type negative electrode plate 2A”.
Further, as shown in FIG. 5B, the through-holes 32A and 32A of the A type negative electrode plate 2A are placed inward in the width direction (left side in the figure) at the middle position in the negative electrode tab 12 of another negative electrode plate 2. A through portion 32B having the same size and the same shape as the through portions 32A and 32A at a position 5 mm and 20 mm away from the outer end edge (right end edge in the drawing) of the negative electrode tab 12, Each 32B was drilled. The negative electrode plate 2 in which the through portions 32B and 32B are thus drilled is hereinafter also referred to as “B type negative electrode plate 2B”.
Further, as shown in FIG. 5 (c), both through portions 32B and 32B of the B-type negative electrode plate 2B are arranged in the width direction inside (left side in the figure) at the middle position in the negative electrode tab 12 of another negative electrode plate 2. The through portion 32C having the same size and the same shape as the through portions 32B and 32B at a position of 10 mm and 25 mm from the outer end edge (right end edge in the drawing) of the negative electrode tab 12. , 32C were drilled. The negative electrode plate 2 having the through portions 32C and 32C drilled in this manner is hereinafter also referred to as “C type negative electrode plate 2C”.

  Of the penetrating portions 31A, 31B, 31C, 32A, 32B, and 32C formed in two places as described above, the A type positive plate 1A, the C type positive plate 1C, the A type negative plate 2A and C The through portions 31A, 31C, 32A, 32C respectively formed at four locations in contact with the one side edge of the positive electrode tab 11 to the negative electrode tab 12 in the type negative electrode plate 2C are indented in a square shape from the side edge. The other through-holes 31A, 31B, 31C, 32A, 32B, and 32C formed at eight locations located inside without contacting the edges of the positive electrode tab 11 or the negative electrode tab 12 are notches. It is a square through hole.

(Production of laminated electrode body)
80 positive electrode plates 1 in total (A type positive electrode plate 1A × 27 sheets + B type positive electrode plate 1B × 27 sheets + C type positive electrode plate 1C × 26 sheets) and 81 negative electrode plates 2 in total (A type negative electrode plate 2A × 27) Sheet + B type negative electrode plate 2B × 27 sheets + C type negative electrode plate 2C × 27 sheets) and a rectangular separator 3a made of polypropylene shown in FIG. 3B (width L5 = 100 mm, height L6 = 120 mm, thickness) 30 μm) were prepared, and as shown in FIG. 6, the positive electrode plates 1 and the negative electrode plates 2 were alternately laminated via the separators 3a. At this time, as shown in FIG. 3C, the separators 3 a on both sides of the positive electrode 1 are formed in a bag shape by thermally welding the peripheral portion with the fusion part 4, and the positive electrode 1 is included in the bag-like separator 3. It was. At that time, the types of the positive and negative electrode plates 1 and 2 are in the order of A → B → C → A →... And the negative electrode plate 2 is positioned on both end surfaces, that is, one point from one end surface to the other end surface. When arranged in order, separator 3a, A type negative electrode plate 2A, separator 3a, A type positive electrode plate 1A, separator 3a, B type negative electrode plate 2B, separator 3a, B type positive electrode plate 1B, separator 3a, C type negative electrode plate 2C, Separator 3a, C-type positive electrode plate 1C, separator 3a, A-type negative electrode plate 2A, separator 3a, A-type positive electrode plate 1A, separator 3a, ... (omitted) ... C-type negative electrode plate 2C, separator 3a Laminated. Subsequently, both end surfaces of this laminated body were connected with an insulating tape 26 (see FIG. 7) for maintaining the shape to obtain a laminated electrode body 10.

[Welding of current collector terminal]
As shown in FIGS. 7 to 9, positive electrode current collectors made of an aluminum plate having a thickness of 0.5 mm are provided on the extended end portions (ie, terminal joint portions) 11C and 12C of the stacked positive electrode tab 11 and negative electrode tab 12, respectively. The terminal 15 and the negative electrode current collecting terminal 16 made of a copper plate having a thickness of 0.5 mm were joined by ultrasonic welding under the conditions shown in Table 1 below.

[Welding of positive and negative tabs]
As shown in FIG. 7 and FIG. 8, only 53 of the positive electrode tabs 11 are formed at the positions where the through portions 31A, 31B, and 31C are formed in the middle position 11M of the 80 positive electrode tabs 11 connecting the positive electrode current collecting terminals 15 and the positive electrode plate 1. Or 54 sheets were ultrasonically welded under the conditions shown in Table 1 below. At this time, the positive electrode tab 11 in which the through portions 31A, 31B, and 31C are formed is not welded at the positions of the through portions 31A, 31B, and 31C, that is, the formation portions of the through portions 31A, 31B, and 31C are skipped. The positive electrode tabs 11 are welded to each other (through the through portions 31A, 31B, 31C). At this time, the through portions 31A, 31B, and 31C that are formed in three different positions are arranged so as to be shifted side by side (in the width direction) one by one as compared to the positive electrode tabs 11 that overlap in the vertical direction. At the positions of the through portions 31A, 31B, 31C, one of the through portions 31A, 31B, 31C is interposed for every three stacked positive electrode tabs 11, and thus each of the through portions 31A, 31B. The number of positive electrode tabs 11 welded at the position of 31C is 2/3 of the total number of stacked positive electrode tabs 11. In the case of the present embodiment, among the 80 positive electrode plates 1 in total, there are 27 A type positive electrode plates 1A and 27 B type positive electrode plates 1B and 26 C type positive electrode plates 1C. At the positions of the through portions 31A and 31B of the 1A through portion 31A, 31A to B type positive electrode plate 1B, 53 positive electrode tabs 11 excluding the positive electrode tab 11 of the 27 A type positive electrode plates 1A to B type positive electrode plate 1B. Are welded, and 54 positive electrode tabs 11 other than the positive electrode tabs 11 of the 26 C type positive electrode plates 1C are welded at the positions of the through portions 31C and 31C of the C type positive electrode plate 1C.

  Further, as shown in FIGS. 7 and 9, only the negative electrode tab 12 is formed at the positions where the through portions 32A, 32B, and 32C are formed at the middle position 12M of the 81 negative electrode tabs 12 connecting the negative electrode current collecting terminal 16 and the negative electrode plate 2. 54 sheets were ultrasonically welded under the conditions shown in Table 1 below. At this time, among the 81 negative electrode plates 2, the A type negative electrode plate 2A, the B type negative electrode plate 2B, and the C type negative electrode plate 2C are uniformly 27 pieces each, so that each of the through portions 32A, 32B, 32C In this position, 54 negative electrode tabs 12 are all welded.

  As shown in FIG. 12, the ultrasonic welding is performed by pressing the tip 33 of an ultrasonic welding machine, which is a welding jig, against each of the positive electrode tab 11 and the negative electrode tab 12. At this time, six tips 33 are provided. Are arranged in a straight line in the horizontal direction, and are configured such that the same six chips 33 are pressed from the opposite side across the positive electrode tab 11 or the negative electrode tab 12 which is a member to be joined. (The chip 33 on the opposite side is not shown). As a result, as shown in FIGS. 8 to 9, the chips 33 are aligned in a straight line along the direction (width direction) perpendicular to the extending direction of the positive electrode tab 11 to the negative electrode tab 12. The terminal joints 11C and 12C and the middle positions 11M and 12M of the positive electrode tab 11 or the negative electrode tab 12 are welded at substantially circular (diameter 5 mm) welding points 31W and 32W, respectively.

  Here, through portions 31A, 31B, and 31C (or through portions 32A, 32B, and 32C) are formed at positions corresponding to the six welding points 31W and 32W, respectively, the welding points 31W and 32W are formed. In this position, the positive electrode tab 11 (or negative electrode tab 12) on which the through portions 31A, 31B, and 31C (or through portions 32A, 32B, and 32C) are formed is not welded, that is, the through portions 31A, 31B, and 31C (or through) The positive electrode tab 11 (or the negative electrode tab 12) is welded so as to skip portions 32A, 32B, and 32C). At this time, the through portions 31A, 31B, and 31C (or through portions 32A, 32B, and 32C) having different formation positions are placed one by one in comparison with the positive electrode tab 11 (or negative electrode tab 12) that overlaps vertically. Since they are arranged so as to be shifted (in the width direction), at the positions of the welding points 31W and 32W, the through portions 31A and 31B are provided for every three positive electrode tabs 11 (or negative electrode tabs 12) stacked. , 31C (or through portions 32A, 32B, 32C) are interposed, and therefore the number of positive electrode tabs 11 (or negative electrode tabs 12) welded at the respective welding points 31W, 32W is laminated. This is 2/3 of the number of all positive electrode tabs 11 (or all negative electrode tabs 12). In the case of the present embodiment, among the 80 positive electrode plates 1 in total, there are 27 A type positive electrode plates 1A and 27 B type positive electrode plates 1B and 26 C type positive electrode plates 1C. At the positions of the through portions 31A and 31B of the 1A through portion 31A, 31A to B type positive electrode plate 1B, 53 positive electrode tabs 11 excluding the positive electrode tab 11 of the 27 A type positive electrode plates 1A to B type positive electrode plate 1B. Are welded, and 54 positive electrode tabs 11 other than the positive electrode tabs 11 of the 26 C type positive electrode plates 1C are welded at the positions of the through portions 31C and 31C of the C type positive electrode plate 1C. In addition, among the 81 negative plates 2, the A type negative plate 2A, the B type negative plate 2B, and the C type negative plate 2C are equally 27 pieces each, so that each of the through portions 32A, 32B, 32C In the position, 54 negative electrode tabs 12 are all welded.

As shown in FIG. 11A, the laminated positive electrode tab 11 (or negative electrode tab 12) is welded so as to press the tip 34 of the ultrasonic welder from above and below, and as a result, FIG. As shown, the positive electrode tab 11 (or the negative electrode tab 12) is joined and integrated at the welding point 31W. At this time, as described above, the number of positive electrode tabs 11 (or negative electrode tabs 12) welded at the welding point 31W is 2/3 of the total number of stacked positive electrode tabs 11 (or all negative electrode tabs 12). Therefore, it is surely joined and integrated without causing poor bonding.
10 and 11 show a situation where the positive electrode tab 11 is welded, and FIG. 10 shows a situation seen from the positive electrode tab 11 side of the A-type positive electrode plate 1A. 10 and 11, for the sake of clarity, the positive tabs 11 of the A-type positive plate 1A, B-type positive plate 1B and C-type positive plate 1C (hereinafter referred to as A-type positive tab 11A and B-type positive tab, respectively). 11B and C-type positive electrode tab 11C), each of which is 6 in total, only 6 are shown. In addition, instead of using the ultrasonic welding machine having six tips 33 on one side as a welding jig to weld at six welding points 31W all at once, a pair of tips on one side is used here. An ultrasonic welding machine having 34 is used to weld six welding points 31W one by one from one end.

  The state of the welding point 31W of the positive electrode tab 11 is schematically shown in cross section in FIG. In the figure, for the sake of clarity, only three positive electrode tabs 11 of an A type positive electrode tab 11A, a B type positive electrode tab 11B and a C type positive electrode tab 11C located in the center of the stacked electrode body 10 in the stacking direction are shown. Yes. In the same figure, the A type positive electrode tab 11A and the C type positive electrode tab 11C enter the penetration part 31B of the B type positive electrode tab 11B from both sides, and are overlapped and joined together in the penetration part 31B. In other words, the A-type positive electrode tab 11A and the C-type positive electrode tab 11C are tightly overlapped and integrated with each other so as to close the thickness gap of the B-type positive electrode tab 11B formed by the through portion 31B.

  In this way, at the welding point 31W of the positive electrode tab 11, the stacked positive electrode tabs 11 enter the respective through portions 31A, 31B, and 31C, and are located above and below the through portions 31A, 31B, and 31C. The tabs 11 are overlapped and joined and integrated, and as a whole, they are joined and integrated toward the center in the stacking direction so as to face each other from above and below. That is, at the welding point 31W, 53 or 54 positive electrode tabs 11 are closely overlapped and joined so as to close the gap of the thickness of the positive electrode tab 11 formed by the through portions 31A, 31B, 31C. Integrated.

[Encapsulation in exterior body]
As shown in FIG. 14, the laminated electrode body 10 is inserted into an exterior body 25 composed of two laminate films 28 formed so that the electrode body can be installed in advance, and a positive current collecting terminal 15 and a negative current collecting terminal The sides where the positive electrode current collector terminal 15 and the negative electrode current collector terminal 16 are heat-sealed so that only 16 protrudes from the exterior body 25, and two of the remaining three sides were heat-sealed.

[Encapsulation and sealing of electrolyte]
LiPF ₆ is 1M (moles) in a mixed solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) are mixed at a volume ratio of 30:70 from one side where the outer package 25 is not thermally welded. The battery was fabricated by injecting an electrolytic solution dissolved at a ratio of 1 / liter) and finally thermally welding one side that was not thermally welded.

(Example)
As the stacked battery of the example, a battery manufactured in the same manner as the battery described in the best mode for carrying out the invention was used.
The battery thus produced is hereinafter referred to as the present invention battery A.

(Comparative example)
A battery was fabricated in the same manner as in the above example, except that the positive electrode tab 11 and the negative electrode tab 12 were welded at a middle position without drilling through portions.
The battery thus manufactured is hereinafter referred to as a comparative battery Z.

[Comparison of the battery of the present invention and a comparative battery]
When the middle positions of the positive electrode tab 11 and the negative electrode tab 12 in the present invention battery A and the comparison battery Z were compared, the present invention battery A1 was reliably welded and in a good joined state, whereas the comparison battery Z It was confirmed that bonding failure occurred.

[Advantages of the battery of the present invention]
In the present invention battery A and the comparative battery Z, the number of stacked positive electrodes 11 is 80, the number of negative electrode tabs 12 is 81, and the number of stacked layers is increased. Since the penetration portions 31A, 31B, 31C, 32A, 32B, and 32C are formed at the joining portions in 11M and 12M, that is, the welding points 31W and 32W, the number of the positive tabs 11 is 53 or 54 sheets and 54 negative electrode tabs 12 are reduced to 2/3 of the total number of laminated sheets, so that welding is ensured and sufficient weldability is secured. Therefore, there is no variation in the connection resistance value between the positive and negative electrode plates 1 and 2 and the positive and negative electrode current collecting terminals 15 and 16, and the amount of energy applied by, for example, ultrasonic welding may be increased. Since it is unnecessary, there is no possibility of the positive electrode tab 11 or the negative electrode tab 12 being broken.

  On the other hand, in the comparative battery Z, since the number of the positive electrode tabs 11 to the negative electrode tabs 12 to be joined is as large as 80 to 81, it is difficult to reliably weld and the weldability becomes insufficient. Therefore, the connection resistance value varies, and if the amount of energy applied by ultrasonic welding is increased in order to ensure welding, the positive electrode tab 11 or the negative electrode tab 12 tends to break.

(Other matters)
(1) In the above embodiment, the A type positive electrode plate 1A, the B type positive electrode plate 1B, and the C type in which the through portions 31A, 31B, and 31C (or through portions 32A, 32B, and 32C) having three different positions are respectively formed. The positive electrode plate (or the A type negative electrode plate 2A, the B type negative electrode plate, and the C type negative electrode plate 2C) is laminated in this order. They may be formed differently. FIG. 15 is a schematic view showing an example in which the positions of the penetrating portions are formed so as to differ in four ways. In the positive electrode plate 1D which is one of the four sheets shown in the figure, it is located at the middle position of the positive electrode tab 11 and at a position 0 mm from the outer edge (the left edge in the figure) of the positive electrode tab 11. A through-hole 31D having the same size and the same shape as the through-hole 31A in the embodiment is drilled, and in the other three positive plates 1E, 1F, 1G, the through-hole of the positive plate 1D Through portions 31E, 31F, and 31G are formed so as to be shifted from the position of 31D to the inner edge (right edge in the drawing) of the positive electrode tab 11 at equal intervals. These four positive electrode plates 1D, 1E, 1F, and 1G are laminated in this order, and the positive electrode tab 11 is welded at four welding points respectively corresponding to the positions of the through portions 31D, 31E, 31F, and 31G. According to this configuration, the number of positive electrode tabs 11 welded at each welding point is 3/4 of the total number of stacked positive electrode tabs 11.

(2) In the above embodiment, the through portions 31A, 31B, 31C, 32A, 32B, and 32C are formed at the middle positions 11M and 12M of the positive electrode tab 11 to the negative electrode tab 12, and the through portions 31A, 31B, 31C, 32A, 53 to 54 positive electrode tabs 11 to 12 negative tabs 12 are joined and integrated at the positions of 32B and 32C, but the penetrating parts are terminal joints 11C of the positive electrode tab 11 to the negative electrode tab 12, In this case, the connection strength between the positive electrode plate 1 or the negative electrode plate 2 and the positive electrode current collecting terminal 15 or the negative electrode current collecting terminal 16 is ensured by ensuring the bonding strength at the terminal bonding portions 11C and 12C. The resistance value can be made uniform, and the joining at the middle positions 11M and 12M can be made unnecessary.
However, in the middle positions 11M and 12M, only the thin positive electrode tab 11 or the negative electrode tab 12 having a thickness of 10 μm to 15 μm per layer is in a laminated state. Only a plurality of positive electrode tabs 11 or negative electrode tabs 12 formed by forming through portions 31A, 31B, 31C, 32A, 32B, and 32C and stacked by the through portions 31A, 31B, 31C, 32A, 32B, and 32C are joined together. In this way, the positive electrode tab 11 or the negative electrode tab 12 can be joined and integrated more easily and reliably, and the connection resistance value between the positive and negative electrode plates 1 and 2 and the positive and negative electrode current collecting terminals 15 and 16 can be obtained. Can be made uniform. Further, since the positive electrode tab 11 or the negative electrode tab 12 are bonded not only at the terminal bonding portions 11C and 12C but also at the middle positions 11M and 12M, the positive electrode tab 11 or the negative electrode tab 12 are more reliably electrically connected. can do.
In addition, it is good also as a structure by which a penetration part is formed in both the middle positions 11M and 12M of the positive electrode tab 11 thru | or the negative electrode tab 12, and the terminal junction parts 11C and 12C, and joining in these both parts is made more reliably. .

(3) In the above embodiment, the positive electrode tab 11 and the negative electrode tab 12 are joined by ultrasonic welding at the positions of the penetrating portions 31A, 31B, 31C, 32A, 32B, and 32C. For example, even if it is performed by a method of mechanically joining a member to be joined, such as a shearing, caulking or screwing that deforms the member to be joined, the through portions 31A, 31B, 31C, 32A, 32B, There is an advantage that the joined state can be made better by 32C, the joining work can be performed with simple equipment, and the battery can be easily and inexpensively manufactured. However, welding is preferable because the resistance can be made uniform.
Further, as a welding method, for example, a resistance welding method or a laser welding method can be used, but ultrasonic welding is particularly desirable in terms of welding strength and the like.

(4) In the above embodiment, the number of the positive electrode tab 11 or the negative electrode tab 12 to be welded at the positions of the penetrating portions 31A, 31B, 31C, 32A, 32B, and 32C is 53 to 54. The number of positive electrode tabs or negative electrode tabs is preferably 60 or less under the same conditions as in the above embodiment. If the number of positive electrode tabs or negative electrode tabs to be welded is 60 or less, welding is reliably performed and sufficient bonding strength is ensured.
In other words, as the total number of stacked positive electrode tabs or negative electrode tabs exceeds 60 (for example, about 80 or more as in the above embodiment), it is difficult to reliably weld and securing the bonding strength is difficult. Therefore, if the total number of stacked positive electrode tabs or negative electrode tabs exceeds 60, and the number of welded positive electrode tabs or negative electrode tabs can be reduced to 60 or less by forming through portions, the configuration of the present invention is particularly useful. It becomes.

(5) In the above-described embodiment, the welding is performed at the six welding points 31W and 32W at the middle positions 11M and 12M of the positive electrode tab 11 or the negative electrode tab 12. However, as described above, the positions of the through portions may be two. If the number of welding points is two or more, the object of the present invention can be achieved. However, in order to ensure the welding strength, it is preferable to use a large number of welding points such as 4 to 6 points.

(6) In the above-described embodiment, welding is performed at six welding points 31W and 32W arranged in a line in the width direction at the middle positions 11M and 12M of the positive electrode tab 11 to the negative electrode tab 12, for example, as shown in FIG. Thus, it is good also as a structure welded by the welding point 41W of 2 or more rows.

(7) In the above embodiment, the positive electrode current collecting terminal 15 is made of an aluminum plate and the negative electrode current collecting terminal 16 is made of a copper plate, but these may be made of a nickel plate. Thus, if the same material is used for both current collecting terminals, the production cost of the battery can be reduced. However, in such a configuration, since dissimilar metals are welded together (because the positive electrode tab 11 is made of aluminum and the negative electrode tab 12 is made of copper), the weldability of the welded portion deteriorates, and The problem of variation in the connection resistance value between the negative electrode plate and the positive and negative current collecting terminals becomes more apparent. Therefore, the configuration as in the present invention is particularly useful because such problems can be suppressed.

(8) In order to suppress variation in the connection resistance value between the positive and negative electrode plates and the positive and negative current collecting terminals, for example, as shown in FIGS. 17 to 19, a plurality of stacked positive electrode tabs Or you may make it arrange | position a negative electrode tab side by side in the width direction. In this example, a positive electrode plate (hereinafter also referred to as a first positive electrode plate) 1L in which a narrow positive electrode tab 11L shown in FIG. 17 is formed at one end portion (left end portion in the drawing) of one short side, and FIG. A positive electrode plate 11R formed at a position shifted from the one end of one short side (the left end in the figure) by the width of the positive electrode tab 11L of the first positive electrode plate 1L (hereinafter also referred to as the second positive electrode plate). 1R). At this time, the first positive electrode plate 1L and the second positive electrode plate 1R are produced by a half of the number of laminated sheets (40 sheets each if the number of the positive electrode plates 1 is 80 as in the above embodiment). At this time, similarly to the case of the above-described embodiment, the positive electrode tabs 11L and 11R are respectively provided with through portions 31L and 31R whose positions are changed in three ways so as to be shifted in the width direction. To keep. Then, as shown in FIG. 19, in a state where the positive electrode tab 11L of the first positive electrode plate 1L and the positive electrode tab 11R of the second positive electrode plate 1R do not overlap, the positive electrode tabs 11L and 11R are connected to the terminal connection portion 11C and the middle position 11M. To weld each. According to this configuration, since the number of welds is further reduced by half, it is possible to more effectively suppress variation in the connection resistance value between the positive electrode plate 1 and the positive electrode terminal 15. Moreover, if the negative electrode plate 2 has the same configuration, the same effect can be exhibited. However, as compared with the one shown in the above embodiment, the width of each of the positive electrode tab 11L of the first positive electrode plate 1L and the positive electrode tab 11R of the second positive electrode plate 1R is narrowed, so that the resistance is slightly increased. Therefore, the structure shown in the above embodiment is preferable.

(9) The positive electrode active material, not limited to the above _{LiCoO 2, LiNiO 2, LiMn 2} O 4 or may be a composites thereof, and the like. Moreover, natural graphite, artificial graphite, etc. are used suitably as a negative electrode active material.

(10) In the above examples, the negative electrode active material layers were formed on both sides of the negative electrode current collector for all the negative electrode plates 2, but the negative electrode active material layers (specifically, not facing the positive electrode plate) There may be no negative electrode active material layer) on the outer side of the outermost negative electrode plate. With such a structure, since the thickness of the laminated electrode body is reduced, the battery can have a higher capacity density.

  The present invention can be suitably applied to, for example, a battery used for a robot, an electric vehicle, a backup power source, and the like.

It is a top view of the positive electrode plate used for the laminated battery of this invention. It is a top view of the negative electrode plate used for the laminated battery of this invention. It is a figure which shows a part of laminated battery of this invention, Comprising: The figure (a) is a top view of a positive electrode, The figure (b) is a perspective view of a separator, The figure (c) is a positive electrode arrange | positioned inside. It is a top view which shows the bag-shaped separator. It is a top view which shows the condition where the penetration part was drilled in the positive electrode tab of the positive electrode plate used for the laminated battery of this invention. It is a top view which shows the condition where the penetration part was pierced in the negative electrode tab of the negative electrode plate used for the laminated battery of this invention. It is a disassembled perspective view of the laminated electrode body used for the laminated battery of this invention. It is a side view of the laminated electrode body used for the laminated battery of this invention. It is a top view which shows the state which welded the positive electrode tabs (middle position) and the positive electrode tab, the positive electrode current collection terminal, and (terminal junction part). It is a top view which shows the state which welded the negative electrode tabs (middle position) and the negative electrode tab, the negative electrode current collection terminal, and (terminal junction part). It is a fragmentary top view which shows the condition of the junction part of positive electrode tabs in a middle position. It is sectional drawing which shows the condition in (A) welding before (a) welding in the AA line part of FIG. It is a disassembled perspective view which shows the welding condition of an electrode plate tab. It is sectional drawing which shows typically the condition of the welding point of a positive electrode tab. It is a perspective view of the laminated battery of the present invention. It is a top view which shows the condition which penetrated the penetration part which concerns on a modification on the positive electrode tab of the positive electrode plate used for the laminated battery of this invention. It is a fragmentary top view which shows the modification of the junction part of positive electrode tabs in a middle position. It is a top view which shows the modification of the positive electrode plate used for the laminated battery of this invention. It is a top view which shows the modification of the positive electrode plate used for the laminated battery of this invention. It is a top view which shows the modification of the laminated electrode body used for the laminated battery of this invention.

Explanation of symbols

11: Positive electrode tab (electrode plate tab)
31A: penetration

Claims (3)

A stacked battery in which a plurality of positive and negative electrode plates are alternately stacked via separators, and a plurality of electrode plate tabs extending from each electrode plate are stacked and bonded to positive and negative current collecting terminals, respectively. There,
A laminated battery comprising: a through portion formed in at least one electrode plate tab; and a plurality of electrode plate tabs joined together through the through portion.   The penetration part is formed between a junction part where the electrode tab is joined to the current collector terminal and the electrode plate, and only the plurality of laminated electrode plate tabs are joined and integrated at the penetration part. The stacked battery according to claim 1, wherein:   The laminated battery according to claim 1 or 2, wherein the joining is performed by ultrasonic welding.

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