JP2007214025A - Laminated cell and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated battery with high reliability against shock and vibration with no possibility of breakage at bending of a positive electrode tab, and a battery pack with excellent volume efficiency and small size. <P>SOLUTION: The laminated battery is provided with a battery element housing part 5 to house a battery element in which a positive electrode tab 1 and a negative electrode tab 2 are drawn out and a sealing part 6 to seal the battery element housing part 5. The positive electrode tab 1 and the negative electrode tab 2 are covered by seal materials 3, 4 at the sealing part 6, and the seal material 3 to cover the positive electrode tab 1 is installed for at least 1.0 mm on the outside from the sealing part 6. Furthermore, the positive electrode tab 1 is bent at the portion covered by the seal material 3 on the outside of the sealing part 6. Furthermore, the battery pack has the laminated batteries connecting the positive electrode tabs themselves or the positive electrode tab and the negative electrode tab, by connecting in parallel and/or in series. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminated battery such as a lithium ion battery covered with a laminated outer covering material, and an assembled battery combining the same.

  In recent years, lithium-ion batteries have been used as power sources for mobile devices such as mobile phones and digital still cameras due to the advantages of high capacity and miniaturization, and power such as power-assisted bicycles and cordless power tools can be handled due to the ability to handle large currents. Laminated lithium ion batteries are used as power sources for applications. There is a demand for higher capacity and smaller size for these power supplies.

  4A and 4B are diagrams illustrating a conventional laminated battery. FIG. 4A is a front view of the laminated battery, and FIG. 4B is a side view. As shown in FIG. 4, the laminated battery has a battery element storage portion 5 comprising a recess formed in advance by embossing or the like on a laminate outer body made of a laminate material in which a synthetic resin film is laminated on both surfaces of a metal thin film such as an aluminum foil. The battery element in which the positive electrode, the negative electrode, and the separator are laminated and the positive electrode tab 1 and the negative electrode tab 2 are pulled out is stored, and the positive electrode tab 1 and the negative electrode tab 2 are laminated so that the tips protrude from the laminate outer package. Of the positive electrode tab 1 and the negative electrode tab 2 in which one side (in this case, the bottom side or the side side) of the laminate outer body is folded to be over the battery element and the fusion part is covered with the sealing materials 3 and 4. Overlay on top. Next, three sides around the battery element housing 5 including the positive electrode tab 1 and the negative electrode tab 2 are heat-sealed to form a sealed portion 6 that is sealed with the positive electrode tab 1 and the negative electrode tab 2 sandwiched therebetween. In order to reduce the size, the sealing portions 6 at the bottom and side portions are bent and manufactured.

  In the laminate battery, a battery pack incorporating a protection circuit or a battery pack in which a plurality of batteries are combined is manufactured. At that time, the positive electrode tab 1 and the negative electrode tab 2 are connected to the protection circuit or between the batteries, but bending is required before or after connection. In the lithium ion battery, aluminum is normally used for the positive electrode tab 1. However, since aluminum is easily broken during bending, the nickel auxiliary tab 11 is connected to the positive electrode tab 1 by ultrasonic welding or the like. The auxiliary tab 11 was bent to prevent breakage.

  Patent Document 1 proposes a battery in which a positive electrode tab drawn from a battery element made of aluminum and an external positive electrode terminal made of nickel are connected by a sealing portion of an exterior body. If the external positive terminal is connected and the sealing is incomplete, the connecting portion may be corroded by the electrolyte or the like. Patent Document 2 proposes a battery that uses pure aluminum or an aluminum alloy annealed material for the positive electrode tab, but there is a problem in workability, particularly cutting, because the aluminum material itself becomes soft. Further, Patent Document 3 proposes a battery using two kinds of sealing materials for improving sealing performance, but does not describe sealing materials outside the sealing portion and bending of the positive electrode tab. .

  FIG. 5 is a side view of an assembled battery in which conventional laminated batteries are combined. When the laminate battery 7 is combined, the positive electrode tab 1 and the negative electrode tab 2 are electrically connected. However, the positive electrode tab 1 and the negative electrode tab 2 extend straight from the sealing portion 6 and are connected at the tip portion. (See Patent Document 4). However, when the positive electrode tab and the negative electrode tab are connected at the tip, the space from the sealing portion 6 of the outer package of the laminated battery 7 to the tip of the positive electrode tab 1 and the negative electrode tab 2 is a space that does not contribute to the capacity of the assembled battery. Therefore, the volume efficiency as an assembled battery is poor.

Japanese Patent Laid-Open No. 11-260343 JP 2002-203534 A JP-A-2005-243526 JP 2005-222787 A

  In the conventional laminated battery, the positive electrode tab is sometimes bent when connecting the protective battery or connecting the laminated batteries as an assembled battery. However, in order to prevent breakage, the auxiliary tab is connected and bent. For this reason, the auxiliary tabs and the man-hours for connecting the auxiliary tabs are required. Further, since the positive electrode tab and the auxiliary tab are connected, the positive electrode tab cannot be bent in the vicinity of the sealing portion, so that a dead space is generated when forming an assembled battery.

  The present invention has been made to solve such problems, and its technical problem is to provide a laminate battery that is highly reliable against impact and vibration without bending even when the positive electrode tab is bent, and has a volume efficiency. A good miniaturized assembled battery is provided.

  The laminate battery of the present invention includes a battery element storage portion that stores a battery element from which a positive electrode tab and a negative electrode tab are drawn, and a sealing portion that seals the battery element storage portion, and the positive electrode tab and the negative electrode The tab is covered with a sealing material at the sealing portion, and the sealing material covering the positive electrode tab is provided at least 1.0 mm outside from the sealing portion. Further, the positive electrode tab is bent at a portion covered with a sealing material outside from the sealing portion. In the assembled battery of the present invention, the laminated battery is formed by connecting the positive electrode tabs or the positive electrode tab and the negative electrode tab in parallel and / or in series.

  According to the present invention, since the positive electrode tab is bent at the portion covered with the sealing material outside the sealing portion, the strength of the positive electrode tab against bending is improved and can be directly connected to other tabs, etc. Auxiliary tabs and auxiliary tab connection processes are not required, and material and man-hours are reduced. In addition, there is an effect that the dead space is reduced by bending near the sealing portion, and the size can be reduced without impairing the reliability of the laminated battery.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an embodiment of a laminated battery according to the present invention. FIG. 1 (a) is a front view of the laminated battery, and FIG. 1 (b) is a side view. FIG. 2 is a diagram for explaining a state after the positive electrode tab of the embodiment of the laminate battery according to the present invention is bent. FIG. 2 (a) is a front view of the laminate battery, and FIG. 2 (b) is a side view. is there.

The production of the laminated battery of the present invention will be described. First, a positive electrode having a positive electrode coating layer containing a positive electrode active material such as LiMn ₂ O ₄ that absorbs and releases lithium ions on a positive electrode current collector made of aluminum foil, and a lithium ion on a negative electrode current collector made of copper foil A battery element is formed by flatly winding or laminating a negative electrode having a negative electrode coating layer containing a negative electrode active material such as graphite, which occludes and releases graphite, via a polyolefin separator. At this time, as the external connection terminal, a positive electrode tab 1 made of aluminum is connected to the positive electrode current collector, and a negative electrode tab 2 made of nickel is connected to the negative electrode current collector.

  This battery element is inserted into a battery element housing 5 in which a recess is formed in advance by embossing or the like in a laminate outer material made of a laminate material in which a synthetic resin film is laminated on both surfaces of a metal thin film such as an aluminum foil. In that case, the positive electrode tab 1 and the negative electrode tab 2 are covered with the sealing materials 3 and 4 with the sealing materials 3 and 4 provided at least 1.0 mm outside the sealing portion, When the positive electrode tab 1 and the negative electrode tab 2 are bent in the process, the positive electrode tab 1 and the negative electrode tab 2 are reinforced. The sealing materials 3 and 4 need only have a width of at least 1.0 mm outside the sealing portion, but are preferably within a width of 5.0 mm so as not to interfere with welding the positive electrode tab 1 and the negative electrode tab 2. The tips of the positive electrode tab 1 and the negative electrode tab 2 are placed in the recesses of the laminate exterior body so as to protrude from the laminate exterior body, and one side (in this case, the bottom side) of the laminate exterior body is folded back on the battery element and the sealing material 3 4 are superimposed on the positive electrode tab 1 and the negative electrode tab 2 coated with 4. Next, the periphery of the battery element housing 5 including the positive electrode tab 1 and the negative electrode tab 2 is heat-sealed leaving the electrolyte injection portion, and the sealing portion 6 is sandwiched between the positive electrode tab 1 and the negative electrode tab 2. Form. Then, after injecting an electrolyte solution by a vacuum impregnation method, the electrolyte solution injection portion is sealed, and the side surface and bottom surface sealing portions 6 are bent to produce a laminated battery 7 as shown in FIG. Here, the sealing materials 3 and 4 improve the adhesion between the positive electrode tab 1 and the negative electrode tab 2 and the laminate exterior material, and damage the positive electrode tab 1 by bending by covering the bent portion when the positive electrode tab 1 is bent later. Will be prevented.

  The laminated battery 7 having such a configuration is connected to a protective circuit depending on the device used, or a plurality of laminated batteries are connected in combination to form an assembled battery. In this case, the laminated battery 7 includes the positive electrode tab 1 and the negative electrode tab 2. Will be bent and connected. As shown in FIG. 2, the positive electrode tab 1 is bent using a jig or the like at a portion where the sealing material 3 outside the sealing portion 6 covers the positive electrode tab 1. The negative electrode tab 2 is bent in the same manner to complete a laminated battery in which the positive and negative electrode tabs are bent. Here, the positive electrode tab 1 and the negative electrode tab 2 are bent in opposite directions, but may be bent in the same direction when connected to a protection circuit without being an assembled battery.

  Next, an embodiment of the assembled battery of the present invention will be described with reference to the drawings. 3A and 3B are diagrams for explaining the assembled battery of the present invention, in which FIG. 3A is a plan view and FIG. 3B is a side view. Laminate batteries 7 in which the positive electrode tab 1 and the negative electrode tab 2 are folded in opposite directions at the portions covered with the sealing material 3 outside the sealing portion are alternately arranged in two each of two types in which the bending directions are reversed, The positive electrode tab 1 and the negative electrode tab 2 are connected by connection means such as ultrasonic welding to obtain an assembled battery having a series connection as shown in FIG. Since the positive electrode tab 1 and the negative electrode tab 2 are connected here because they are connected in series, the tabs of the same polarity are connected in parallel connection, but the length of the positive and negative electrode tabs is necessary for connection. The length can be adjusted.

  As shown in FIG. 1, a positive electrode tab 1 made of aluminum having a width of 12 mm and a thickness of 0.2 mm, and a negative electrode tab 2 made of nickel having a width of 12 mm and a thickness of 0.2 mm were pulled out, a width of 60 mm, a height of 68 mm, A laminated outer package in which a battery element having a thickness of 12 mm is covered with a sealing member 6 having a thickness of 0.1 mm and a sealing member 6 of a positive electrode tab 1 and a negative electrode tab 2 are laminated, and a synthetic resin film is laminated on both surfaces of an aluminum foil. After being inserted into the battery element storage part 5 formed by embossing, it is folded at the bottom and overlapped on the battery element and on the positive electrode tab 1 and the negative electrode tab 2 covered with the sealing materials 3 and 4, and the electrolyte injection part The periphery of the battery element storage part except for was heat-sealed. At this time, the sealing materials 3 and 4 were provided 1.0 mm outside from the sealing portion 6. After the electrolyte injection, the electrolyte injection part was sealed, and the side and bottom sealing parts 6 were bent.

  Next, as shown in FIG. 2, the positive electrode tab 1 is bent 90 degrees with a radius of curvature R0.5 using a jig or the like where the sealing material 3 outside the sealing portion 6 covers the positive electrode tab 1. Went. At the time of bending, the bent portion of the positive electrode tab 1 needs to be covered with the sealing material 3, but even if the portion covered with the sealing material becomes long, the bending is not particularly affected. It may be long. The negative electrode tab 2 was bent in the direction opposite to the positive electrode tab 1.

A laminate battery 7 in which the positive electrode tab 1 and the negative electrode tab 2 are bent and a laminate battery 7 in which the positive electrode tab 1 and the negative electrode tab 2 are bent in the opposite direction to each other are alternately arranged in two types. 2 were connected, and four assembled batteries in series as shown in FIG. 3 were assembled. The volume including the space occupied by the positive electrode tab 1 and the negative electrode tab 2 of this assembled battery was 201.6 cm ³ (width 60 mm, height 70 mm, thickness 48 mm), and was manufactured by connecting an auxiliary tab to the conventional positive electrode tab. 94.6% of the assembled battery volume 213.1 cm ³ (width 60 mm, height 74 mm, thickness 48 mm), and the assembled battery volume connected at the tip of the positive electrode tab and the negative electrode tab as shown in FIG. The volume was 87.5% compared to 230.4 cm ³ (width 60 mm, height 80 mm, thickness 48 mm), and the volume could be reduced.

FIG. 1A is a front view of a laminated battery, and FIG. 1B is a side view of an embodiment of a laminated battery according to the present invention. Explanatory drawing of the state after bending the positive electrode tab of embodiment of the laminated battery of this invention, Fig.2 (a) is a front view of a laminated battery, FIG.2 (b) is a side view. Explanatory drawing of the assembled battery of this invention, Fig.3 (a) is a top view, FIG.3 (b) is a side view. FIG. 4A is a front view of a laminate battery, and FIG. 4B is a side view of a conventional laminate battery. The side view of the assembled battery which combined the conventional laminated battery.

Explanation of symbols

1 Positive electrode tab 11 Auxiliary tab 2 Negative electrode tab
3,4 Seal material 5 Battery element storage part 6 Sealing part 7 Laminated battery

Claims (3)

  A battery element housing portion for housing the battery element from which the positive electrode tab and the negative electrode tab are drawn out; and a sealing portion for sealing the battery element housing portion, wherein the positive electrode tab and the negative electrode tab are sealed in the sealing portion. And a sealing material covering the positive electrode tab is provided at least 1.0 mm outside from the sealing portion.   The laminate battery according to claim 1, wherein the positive electrode tab is bent at a portion covered with an outer sealing material from the sealing portion.   The assembled battery according to claim 2, wherein the positive electrode tabs or the positive electrode tab and the negative electrode tab are connected to each other and connected in parallel and / or in series.

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