JP2006012589A - Battery, its manufacturing method, and battery pack using the battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery, its manufacturing method, and a battery pack using the battery, where manufacturing cost of the battery is reduced without incurring increase in the number of part items and complexity of a processing process, and the connection between a sealing plate of the battery and an insert resin is strengthened without impairing miniaturization of the battery pack with an anchor strength of an under cut portion formed in the sealing plate maintained. <P>SOLUTION: A battery 1 has an outer case which houses an electrode body. The outer case is sealed with a sealing plate 5. Under cut recesses 7 are formed in the sealing plate 5, and the depth of the under cut recess 7 is less than the thickness of the sealing plate 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery suitable for a battery power source of various portable electronic devices and a pack battery that is miniaturized using the battery.

  Various portable electronic devices such as mobile phones have been reduced in size and weight, and as these devices have become more sophisticated and multifunctional, the batteries that serve as the power source for these devices have higher capacity and smaller size. Thin type is required. As a battery used as a power source for these devices, a light-weight, high-voltage, high-capacity lithium ion battery is often used. In the case of using a lithium ion battery, in order to protect the battery from overcharge, overdischarge, overcurrent, etc., it is used as a pack battery by incorporating a protection circuit and a protection element together with the battery. When a protection circuit is built in, a protective element such as a thermal fuse or PTC element and other circuit components such as an FET are mounted on the printed circuit board, and a metal plate serving as an external connection terminal is fixed on the printed circuit board, or A resin terminal holder to which the external connection terminals are fixed is separately provided, and the printed circuit board and the terminal holder are accommodated in the battery pack. On the other hand, when the protection circuit is simplified and protection elements such as thermal fuses, breakers, and PTC elements are built in without being mounted on a printed circuit board, for example, these protection elements are connected to a terminal holder to which external connection terminals are fixed. And housed in the battery pack together with the battery. Also known is an external connection terminal provided with a metal plate fixed directly to the surface of the protective element case.

  Lithium-ion battery packs used as power sources for such devices as mobile phones do not use a hard resin case as the outer case in order to reduce the size of the battery. For example, a terminal holder is placed on the battery sealing plate. A small and thin pack battery has been developed in which a battery case and a terminal holder are molded together with an insert resin together to form a pack battery.

At this time, polyamide resin, polyurethane resin, or polyolefin resin that can be molded at low temperature and low pressure is used as the insert resin to be molded. However, in order to prevent these resins from being removed from the battery after molding, It is necessary to make it adhere firmly (refer patent document 1).
As shown in FIG. 1, the battery pack described in this publication includes an undercut component 3 on a sealing plate 5 that seals an opening of an outer can of the battery 1. Then, the battery 1 and the terminal holder 2 provided with external connection terminals and the like are connected in the mold by a lead plate or the like, and the terminal holder 2 is arranged on the sealing plate 5 to form a core pack. The pack is positioned in the mold, the melted insert resin 6 is filled in the mold, and after drying, is released from the mold to complete the pack battery.

  In this battery pack, the shape of the undercut component 3 is formed such that the upper surface protrudes in the horizontal direction with respect to the shaft-shaped convex portion 3-1, so that the melted insert resin 6 is below the upper surface from which the molten insert resin 6 protrudes in the horizontal direction. Go around. For this reason, the insert resin 6 and the undercut component 3 can be caught, and the sealing plate 5 and the insert resin 6 can be firmly connected.

  However, in the battery pack having this structure, the undercut component 3 must be attached in advance to the upper surface of the sealing plate 5. In FIG. 1, the undercut component 3 is fixed to the upper surface of the sealing plate 5 by, for example, a welding portion 4. For this reason, the undercut component 3 is prepared as a separate component, and welding to the sealing plate 5 is required, which increases the number of components and makes the machining process complicated, resulting in an increase in manufacturing cost. is there.

  Furthermore, since it is necessary for the undercut component 3 to form a space where the resin wraps between the upper surface of the undercut component 3 and the sealing plate 5, the height of the convex portion 3-1 must be increased. As a result, there is a problem that the height of the battery pack 1 is increased, which hinders downsizing.

  The present invention has been developed with the object of solving these problems, and suppresses the manufacturing cost without increasing the number of parts or complicating the processing process, and hinders downsizing of the battery pack. Without providing the anchor strength of the undercut portion provided in the sealing plate, and providing a battery that strengthens the connection between the sealing plate of the battery and the insert resin, its manufacturing method, and a battery pack using the battery It is.

  The battery of the present invention is characterized in that, in a battery in which an outer can containing an electrode body is sealed with a sealing plate, an undercut recess having a small opening is provided in the thickness of the sealing plate.

  In addition, an inclined recess for inclining an inner peripheral wall of the undercut recess is provided in a peripheral portion of the undercut recess.

  Further, the undercut concave portion is formed in a ring shape, and a mortar-shaped inclined concave portion is formed in a central portion of the ring-shaped undercut concave portion.

The battery manufacturing method of the present invention is characterized in that an undercut recess is formed by the following steps.
(1) A step of forming a recess and a built-up portion located around the recess on the sealing plate by press working.
(2) A step of crushing the built-up portion into a taper shape by pressing so that the built-up portion is inclined inward from the periphery of the concave portion.
(3) The step which makes the inclined build-up part flush with the upper surface of a sealing board by press work.

  The battery pack of the present invention is a battery in which an outer can containing an electrode body is hermetically sealed with a sealing plate, and an undercut recess having a small opening is provided in the thickness of the sealing plate; And an external connection terminal connected to the battery and the protection element, and an insert resin for connecting the battery, the protection element and the external connection terminal, and the insert resin is filled in the undercut recess, and the battery and the protection element And the external connection terminal are integrally coupled.

  According to the battery of the present invention, since the undercut concave portion is provided in the sealing plate, the number of parts can be reduced without using an undercut part as a separate part as shown in FIG. Moreover, since this undercut recessed part is provided in the plate | board thickness of a sealing board, it does not protrude from the upper surface of a sealing board, and a battery and a battery pack do not become larger than necessary. Further, since the undercut concave portion has a small opening, it is possible to prevent the resin from coming out after being filled with the melted insert resin. As a result, the anchor strength of the undercut recess can be maintained, and the connection between the battery sealing plate and the insert resin can be strengthened.

  Further, according to the battery of the present invention, since the inclined concave portion for inclining the inner peripheral wall of the undercut concave portion is provided in the peripheral portion of the undercut concave portion, the opening of the undercut concave portion can be inclined at an acute angle. It is possible to further prevent the insert resin from slipping out.

  Further, since the undercut recess is formed in a ring shape, and a mortar-shaped inclined recess is formed in the center of the ring-shaped undercut recess, the entire area of the inner peripheral wall of the undercut recess can be inclined. The entire circumference of the opening of the ring-shaped undercut recess can be inclined at an acute angle, and the insert resin can be further prevented from coming out.

  Next, according to the battery manufacturing method of the present invention, each step of forming the undercut concave portion is performed by pressing, so that the processing step can be easily performed. At this time, by performing the step of crushing the built-up portion into a taper shape, the built-up portion is inclined inward from the periphery of the recessed portion, and as a result, the opening of the undercut recessed portion is reduced. be able to.

  In addition, according to the battery pack of the present invention, the anchor strength of the undercut portion is maintained without hindering downsizing by filling the undercut concave portion formed in the thickness of the sealing plate with the insert resin. The connection between the battery sealing plate and the insert resin can be strengthened.

  Embodiments of the present invention will be described with reference to the drawings. 1 is a battery. This battery 1 is a rectangular lithium ion battery, in which a positive electrode plate, a negative electrode plate, and a separator are spirally wound inside a bottomed cylindrical outer can that is open on one side, and the electrode body and an electrolysis are made flat. Contains liquid. And the sealing board 5 is sealed by the laser welding to the opening part of the armored can. The material of the outer can is an aluminum alloy containing manganese or the like, and the material of the sealing plate 5 is made of aluminum. A negative electrode terminal 17 electrically connected to the negative electrode plate of the electrode body protrudes from the central portion of the sealing plate 5 and is fixed to the sealing plate 5 via an insulating material. The sealing plate 5 and the negative electrode terminal 17 is electrically insulated. On the other hand, the outer can and the sealing plate 5 are also used as the positive electrode terminal of the battery 1. The positive electrode terminal can be taken out by welding the lead plate 18 to the region of the sealing plate 5 excluding the negative electrode terminal 17. The sealing plate 5 is provided with a safety valve 19. The safety valve 19 is formed in a foil shape by reducing the thickness of the sealing plate 5, and when the internal pressure rises due to overcharging of the lithium ion battery, the safety valve 19 is activated to safely release the gas. Yes. The battery 1 does not have to be limited to a lithium ion battery, and may be other types of batteries. In addition, a cylindrical battery or a sealing method of a sealing plate is not a laser welding but a caulking method. A battery having a structure may be used.

Reference numeral 2 denotes a resin terminal holder. As shown in FIGS. 9 and 10, the terminal holder 2 is formed by insert-molding a plurality of metal plates such as nickel plates in advance. An electrode window 25 that exposes the metal plate is formed in the terminal holder 2, and the metal plate exposed from the electrode window 25 is used as the external output terminal 20. A total of three external output terminals 20 are formed, and an output terminal connected to the positive and negative electrodes of the battery 1 and a signal terminal for identifying the model of the battery 1 and the like are provided. The external output terminal 20 is electrically connected to a contact on the device side such as a mobile phone, but may be plated with gold in order to reduce contact resistance.
One end of the metal plate serving as the positive electrode terminal of the external output terminal 20 is electrically connected by resistance spot welding to an L-shaped lead plate 18 that is resistance spot welded to the sealing plate 5. At this time, a clad material 21 having a two-layer structure of an aluminum layer and a nickel layer is ultrasonically welded to the sealing plate 5 in advance so that the L-shaped lead plate 18 is easily spot-welded to the sealing plate 5. The L-shaped lead plate 18 is resistance spot welded to the nickel layer that is the upper layer of the clad material 21.

  One end of the metal plate serving as the negative electrode terminal of the external output terminal 20 is connected to the negative electrode terminal 17 of the battery 1 through the protective element 22. As the protection element 22, a PTC element whose resistance value increases rapidly when the temperature rises or a breaker using a bimetal whose contact opens when the temperature rises is used. Since the protection element 22 is connected in series with the electrode of the battery, when an overcurrent flows through the battery 1, the overcurrent also flows through the protection element 22 and the element itself generates heat due to Joule heat. The resistance value is dramatically increased. In the case of a breaker, the contact is opened, the overcurrent flowing through the battery 1 is interrupted to protect the battery 1 safely, and further increase in temperature of the battery pack is prevented. In addition, even when the battery 1 is overcharged, the battery 1 may generate heat. However, since the protective element 22 is disposed close to the battery 1, the protective element 22 increases the ambient temperature even in this case. In response, the PTC element can increase the resistance value, or the breaker can open the contact.

  Next, 7 is an undercut recessed part, and it is provided so that the opening part faces the upper surface within the thickness of the sealing plate 5. As shown in FIG. 9, the undercut recess 7 is formed in a ring shape on both sides of the sealing plate 5. The undercut recess 7 has a large bottom and a small opening. A mortar-shaped inclined recess 16 is formed at the center of the ring-shaped undercut recess 7. By forming the inclined recess 16, the meat of the sealing plate 5 is brought inward of the undercut recess 7. In contrast to the undercut recess 7, the inclined recess 16 is formed in a mortar shape having a wide opening and a small bottom, so that a lot of meat is brought closer to the opening side. As a result, the undercut recess 7 It can be made to incline so that an inner peripheral wall may become so narrow that an opening part.

Here, a method of forming the undercut recess 7 having a small opening will be described. In order to obtain the undercut recess 7 of the present invention, the following three experiments were performed.
(Experiment 1: Fig. 3)
(1) Press working is performed on the surface of the aluminum metal plate 8 to be the sealing plate 5 with a punch 9 in which the shape of the press surface is concave and the periphery of the convex is recessed, In addition to forming the raised portion 10, pressing is also performed from the back surface of the metal plate 8 with a convex punch to form a meat push-up portion 11.
(2) Next, the surface of the metal plate 8 is pressed by a punch having a flat press surface shape, and the build-up portion 10 is crushed so that the surface of the metal plate 8 is flush with the undercut recess. Form.

  As for this undercut recessed part, it was confirmed that the peripheral part of an opening part will turn into the R-shaped part 12. FIG. Even when the melted insert resin 6 was filled in the undercut recess, the resin was easily removed due to the slip and ductility of the resin, and the anchor strength could not be increased.

(Experiment 2: Fig. 4)
(1) The pressing process is performed on the surface of the metal plate 8 with a punch 9 having a ring-shaped convex part, a central part of the convex part, and a peripheral part of the convex part. In addition to forming the portion 10, pressing is also performed from the back surface of the metal plate 8 with a convex punch to form the meat push-up portion 11. At this time, in addition to the build-up portion 10 formed around the recess as in Experiment 1, a build-up portion is also formed in the central portion 13.
(2) In the same manner as in Experiment 1, the surface of the metal plate 8 is pressed by a punch having a flat press surface shape, and the build-up portion 10 is crushed so that the surface of the metal plate 8 is flush with the undersurface. A cut recess is formed.

Compared to Experiment 1, this undercut recess is formed in a ring shape so that the filled insert resin is caught by the inner periphery and the outer periphery of the ring recess. Even in this case, it was confirmed that the peripheral portion of the opening becomes the R-shaped portion 12. Therefore, as in Experiment 1, even when the melted insert resin 6 was filled in the undercut recess, the resin was easily removed due to the slip and ductility of the resin, and the anchor strength could not be increased.
(Experiment 3: Fig. 5)
(1) As in Experiment 2, the surface of the metal plate 8 was pressed with a punch 9 having a ring-shaped convex portion, a central portion of the convex portion, and a peripheral portion of the convex portion, and the metal plate 8 was pressed. The build-up portion 10 is formed on the front surface of the metal plate 8, and press working is also performed from the back surface of the metal plate 8 with a convex punch to form the meat push-up portion 11. At this time, in addition to the build-up portion 10 formed around the recess as in Experiment 1, a build-up portion is also formed in the central portion 13.
(2) Using the wedge-shaped punch 15, a peripheral taper-crushing portion 14 is formed around the built-up portion 10 by pressing, and the opening of the concave portion is inclined inward.
(3) In the same manner as in Experiment 1, the surface of the metal plate 8 is pressed by a punch having a flat press surface, and the build-up portion 10 is crushed so that the surface of the metal plate 8 is flush with the undersurface. A cut recess is formed. At this time, a mortar-shaped inclined concave portion 16 is formed in the center portion of the ring-shaped undercut concave portion by the peripheral taper crushing portion 14 formed in the step (2).

  The undercut concave portion is moved inward of the undercut concave portion 7 by performing the step (2) between the steps (1) and (3). In contrast to the undercut recess 7, the inclined recess 16 is formed in a mortar shape having a wide opening and a small bottom, so that a lot of meat is brought closer to the opening side. As a result, the undercut recess 7 It was possible to incline so that the inner peripheral wall was narrower toward the opening. Then, when the melted insert resin 6 was filled in the undercut recess, the resin could be firmly held and the anchor strength could be increased.

The battery 1 is assembled using the sealing plate 5 in which the undercut recess 7 is formed as in Experiment 3, and the battery pack is assembled using the battery 1. The battery pack is assembled as follows.
(1) The negative electrode terminal 17 of the battery 1 and the terminal plate provided at one end of the protective element 22 are resistance spot welded, and the L-shaped lead plate 18 and the external output terminal that are resistance spot welded to the sealing plate 5 One end of a metal plate serving as a positive electrode terminal 20 is resistance spot welded to form a core battery in which the battery 1, the protection element 22, and the terminal holder 2 are integrated.
(2) The core battery is positioned and arranged in the mold, and the insert resin 6 is filled into the mold from the insert resin filling port 23. As the insert resin 6, a polyamide resin, a polyurethane resin, a polyolefin resin, or the like that can be molded at a low temperature and a low pressure is used.

At this time, the insert resin 6 fills the inside of the undercut recess 7 formed in the sealing plate 5. Further, projecting portions 24 are formed at both ends in the longitudinal direction of the terminal holder 2, and the resin also wraps around the projecting portions 24.
(3) After the insert resin 6 is dried, the battery pack is released from the mold and taken out.

  In the battery pack formed in this way, the insert resin 6 is filled in the periphery of the protruding portion 24 of the terminal holder 2 and the undercut concave portion 7 provided in the battery 1, and these can be integrally and firmly connected. Therefore, even if the resin portion of the battery pack is pulled or an impact such as twisting or dropping is applied, the resin 6 can be prevented from peeling off. Further, in order to firmly connect these, a label may be wound around the whole battery pack so as to cover the boundary between the insert resin 6 and the battery 1. FIG. 10 shows another embodiment of the present invention, and the undercut recess 7 can be provided in a wide area of the entire sealing plate 5 to further increase the connection strength.

Explanatory drawing which shows the undercut part of the conventional battery pack Explanatory drawing which shows the undercut part of the battery pack of this invention Procedure diagram showing how to form undercut recess Procedure diagram showing how to form undercut recess Procedure diagram showing how to form undercut recess The exploded perspective view of the battery pack of the present invention Plan view of the battery sealing plate of the present invention Exploded sectional view of the battery and terminal holder of the present invention Assembly drawing of the battery pack of the present invention Explanatory drawing which shows the other Example of the battery pack of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Terminal holder 3 ... Undercut component 3-1 ... Convex part 4 ... Welded part 5 ... Sealing plate 6 ... Insert resin 7 ... Undercut recessed part 8 ... Metal plate 9 ... Punch 10 ... Overlay part 11 ... Push up Part 12 ... R-shaped part 13 ... Central part 14 ... Peripheral taper-crushing part 15 ... Wedge-shaped punch 16 ... Inclined recess 17 ... Negative electrode terminal 18 ... Lead plate 19 ... Safety valve 20 ... External output terminal 21 ... Cladding material 22 ... Protection element 23 ... Insert resin filling port 24 ... Projection 25 ... Electrode window

Claims (5)

  A battery in which an outer can containing an electrode body is sealed with a sealing plate, and an undercut recess having a small opening is provided in the thickness of the sealing plate.   2. The battery according to claim 1, wherein an inclined concave portion for inclining an inner peripheral wall of the undercut concave portion is provided in a peripheral portion of the undercut concave portion.   The battery according to claim 2, wherein the undercut concave portion is formed in a ring shape, and a mortar-shaped inclined concave portion is formed in a central portion of the ring-shaped undercut concave portion. A method of manufacturing a battery, comprising forming an undercut recess by the following steps. (1) A step of forming a recess and a built-up portion located around the recess on the sealing plate by press working.
(2) A step of crushing the built-up portion into a taper shape by pressing so that the built-up portion is inclined inward from the periphery of the concave portion.
(3) The step which makes the inclined build-up part flush with the upper surface of a sealing board by press work.   The outer can containing the electrode body is sealed with a sealing plate, and the battery is provided with an undercut recess having a smaller opening within the thickness of the sealing plate, the battery protection element, and the battery and the protection element are connected. The external output terminal and an insert resin for connecting the battery, the protective element, and the external output terminal, and the insert resin is filled in the undercut recess so that the battery, the protective element, and the external output terminal are integrated. A battery pack characterized by being bonded to the battery pack.

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