JP2008204770A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a square type battery in which floating-up or tilting of a frame body and deformation of a lead terminal are suppressed, which has no possibility of internal short-circuit, and which has high reliability in order to prevent occurrence of the internal short circuit by means that the lead terminal drawn out from an electrode plate is contacted with the interior or the like of a bottomed case, by means that a resin-made frame body connected to the lower part of a sealing body is arranged at the upper part of electrode body in a bottomed case and an insertion state of this frame body is made stabilized. <P>SOLUTION: In this square type battery, by means that the frame body 4 is attached to the lower part of the sealing body 5 and that an insulator 4 is arranged together with the sealing body 5 at the opening part of the bottomed case 1, the insulator 4 can be arranged at the upper part of the electrode body 3 of the bottomed case 1 in a stable state. As a result, the floating-up or the tilting of the insulator 4 and the deformation of the lead terminal 2 can be suppressed even when excessive vibrations or impacts are applied to the square type battery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery in which an insulator is disposed between a sealing body and an electrode body, and more particularly to a configuration for preventing an internal short circuit of a prismatic lithium ion secondary battery.

  In recent years, consumer electronic devices such as notebook computers, mobile phones, and AV devices are rapidly becoming portable and cordless, and secondary batteries that are small, lightweight, and have high energy density to drive power for these electronic devices. The demand for is increasing.

  Non-aqueous electrolyte secondary batteries, in particular lithium ion secondary batteries, are batteries having high voltage and high energy density, and are therefore mainly used in notebook computers, mobile phones, AV equipment and the like. In particular, prismatic lithium ion secondary batteries are being actively developed because they are excellent in load characteristics and life characteristics, are suitable for thinning electronic devices, and have good space efficiency.

In a rectangular lithium ion secondary battery, lead terminals are attached to both electrode plates of an electrode body, which is connected to an internal terminal, and electricity is taken out through an external terminal connected to the internal terminal. When using a metal bottomed case, the lead terminal connected to the electrode plate having the same polarity as the bottomed case is directly connected to the bottomed case or a metal lid connected to the bottomed case. It is connected to the. The lead terminal connected to the pole plate with a polarity different from that of the metal bottomed case is connected to the internal terminal, and the internal terminal is insulated by the bottomed case or metal lid and gasket. If the electrode body moves due to the above, the lead terminal may be deformed and contact the inside of the bottomed case or the like to cause an internal short circuit. In order to prevent this, a resin insulator called a frame is generally installed on top of an electrode body housed in a bottomed case (see, for example, Patent Documents 1 and 2).
JP-A-8-69815 JP 2001-229898 A

  However, since such a conventional insulator has only a resin insulator called a frame disposed above the electrode body housed in the bottomed case, the frame is used as an electrode in the bottomed case. When inserting into the upper part of the body, the inserted state of the frame body may become unstable due to lot-to-lot variations such as the inner dimensions of the bottomed case and the electrode body. As a result, the frame body is lifted or tilted, and the lead terminal is deformed to come into contact with the inner surface of the bottomed case and the like to cause an internal short circuit, thereby reducing the open circuit voltage.

  The present invention solves the above-mentioned problem, and by attaching an insulator to the lower part of the sealing body, when the opening of the bottomed case is sealed with the sealing body, the insulator is placed in the bottomed case together with the sealing body. Because it can be stably placed on the top of the electrode body, the lead terminal may be deformed by floating or tilting like a conventional frame body, contacting the inner surface of the bottomed case, etc. An object of the present invention is to provide a battery with high reliability without any problem.

In order to solve the above-described problems, the present invention accommodates an electrode body and an electrolytic solution in which a belt-like positive electrode plate and a negative electrode plate connected with lead terminals are laminated or wound in a spiral shape via a separator. A battery having a bottomed case and a sealing body that seals an opening of the bottomed case, and an insulator for insulating the lead terminal and the bottomed case or the electrode body is attached to a lower portion of the sealing body It is characterized by that.

  According to this configuration, the insulator attached to the lower portion of the sealing body is stably disposed on the upper portion of the electrode body in the bottomed case together with the sealing body. In addition, since this insulator is attached to the sealing body, the insulator does not tilt after being inserted into the bottomed case, and even if the electrode body moves due to vibration or drop impact, the lead terminal is deformed, etc. Thus, it is possible to obtain a highly reliable battery that does not cause an internal short circuit and a decrease in open circuit voltage.

  According to the present invention, the insulator is attached to the lower portion of the sealing body, and when the opening of the bottomed case is sealed by the sealing body, the insulator is stably disposed on the upper portion of the electrode body in the bottomed case together with the sealing body. As a result, the lead terminal is deformed due to floating or tilting like a conventional frame body, and it contacts the inner surface of the bottomed case to provide a highly reliable battery that does not cause an internal short circuit and reduce open circuit voltage. can do.

  In the present invention, an electrode body formed by laminating or winding a strip-like positive electrode plate and a negative electrode plate connected with lead terminals via a separator, and a bottomed case containing an electrolyte therein, and this The battery includes a sealing body that seals the opening of the bottom case, and an insulator for insulating the lead terminal from the bottomed case or the electrode body is attached to a lower portion of the sealing body.

  According to this configuration, the insulator attached to the lower portion of the sealing body is stably disposed on the upper portion of the electrode body in the bottomed case together with the sealing body. In addition, since this insulator is attached to the sealing body, it will not tilt after being inserted into the bottomed case, so even if the electrode body moves due to vibration or drop impact, the lead terminal will not be deformed. Thus, a highly reliable battery that does not cause an internal short circuit and a decrease in open circuit voltage can be obtained. In addition, an effect of omitting the step of inserting the frame body into the upper portion of the electrode body in the bottomed case as in the prior art can be obtained.

  The insulator has a bottom plate portion that insulates the lead terminal from the electrode body, and an outer wall portion that is perpendicular to the bottom plate portion and that is disposed on the outer peripheral surface of the bottom plate portion and insulates the bottomed case. You may provide the elastic part which absorbs the dimensional difference between a sealing body and an electrode body in at least one part of a part.

  According to this configuration, even when excessive vibration or impact is applied, the insulator attached to the sealing body is elastic, so that the vertical movement of the electrode body housed in the bottomed case is absorbed. The effect that the deformation of the lead terminal can be further suppressed is obtained. Moreover, the effect that the elastic part can absorb the dimensional variation between the lots of the electrode body and the bottomed case is obtained.

  Further, the elastic portion may have a bellows shape.

  According to this configuration, it is possible to easily provide an effective elastic portion in the insulator.

  Further, the elastic portion may be waved.

  According to this structure, the same effect as the above-described bellows shape can be obtained. Further, since it is easy to provide an elastic portion having a relatively high strength, it is effective for a large-sized battery in which a large-capacity electrode body is accommodated in a bottomed case, for example.

  The elastic portion may be thin.

According to this configuration, elasticity can be added to the insulator with a simple configuration in which a thin wall is provided in part of the insulator. The thin-walled portion is curved with respect to the vertical impact and vibration of the electrode body and can absorb the shock and vibration. In addition, there is an effect that the strength of elasticity can be adjusted by adjusting the thickness of the thin-walled portion. Furthermore, there is an effect that it can be formed in a smaller space than an accordion-like or wavy elastic part.

  The elastic portion may be bent in a diagonally downward inward direction.

  According to this configuration, it is possible to add elasticity to the insulator only by partially changing the shape of the insulator.

  The elastic part may be a rubbery part.

  According to this configuration, excellent elasticity can be added even with an insulator having the same shape.

  The rubber part may be a polyurethane resin.

  According to this structure, the elastic part excellent also in organic-solvent resistance can be provided.

  The polyurethane resin may be a polyurethane elastomer.

  According to this structure, the effect which was further excellent in organic-solvent resistance is acquired.

  In addition, by attaching an insulator for insulating the lead terminal and the bottomed case or the electrode body at the lower part of the sealing body in this way, the insulator is also affected by the inner dimensions of the bottomed case and variations among lots of the electrode body. There is no possibility that the insertion state of the lead wire will be unstable, and even if excessive vibration or drop impact is applied, the lead terminal may contact the inner surface of the bottomed case, etc. A highly reliable battery can be provided.

(Example 1)
FIGS. 1A and 1B are schematic cross-sectional views of the main part of the battery showing the configuration of Example 1 of the present invention.

  An electrode body formed by winding a strip-like negative electrode plate and a positive electrode plate, in which a lead terminal 2 made of a nickel plate material is connected, to a bottomed case 1 made of an aluminum alloy via a separator made of porous polyethylene in a spiral shape 3 was stored.

  The insulator 4 is composed of a bottom plate portion 4b and an outer wall portion 4a that is perpendicular to the bottom plate portion 4b and disposed on the outer peripheral surface of the bottom plate portion 4b. The bottom plate portion 4b is provided with a hole portion 4c through which the lead terminal 2 passes. The insulator 4 was made of polypropylene resin and was molded by resin molding. This insulator 4 was attached to the lower part of the sealing body 5.

  Next, the leading end of the lead terminal 2 is passed through the hole 4c of the insulator 4 and laser-welded to the lower portion of the sealing body 5, and the lead terminal 2 is bent to open the insulator 4 together with the sealing body 5 to the opening of the bottomed case 1. Placed in the department. The sealing body 5 and the bottomed case 1 are laser welded, and a non-aqueous electrolyte is injected into the bottomed case 1 through the liquid injection hole on the top of the sealing body 5, and then the liquid injection hole is sealed. A square lithium ion secondary battery was produced.

(Example 2)
FIG. 2 is a schematic sectional view showing the structure of the insulator 4 used in Example 2 of the present invention.

  As shown in FIG. 2, the prismatic lithium ion secondary battery manufactured in the same manner as in Example 1 except that the outer wall 4a of the insulator 4 is provided with a bellows portion that expands and contracts in a bellows shape to form an elastic portion 4d. Example 2 was adopted.

(Example 3)
FIG. 3 is a schematic sectional view showing the configuration of the insulator 4 used in Example 3 of the present invention.

  As shown in FIG. 3, a prismatic lithium ion secondary battery manufactured in the same manner as in Example 1 except that an elastic portion 4d is provided by providing a corrugated portion that expands and contracts in a corrugated shape on the outer wall portion 4a of the insulator 4. Example 3 was adopted.

Example 4
FIG. 4 is a schematic sectional view showing the structure of the insulator 4 used in Example 4 of the present invention.

  As shown in FIG. 4, Example 1 is provided except that a bent portion is provided between the outer wall portion 4a and the bottom plate portion 4b so that the bottom plate portion 4b of the insulator 4 is bent obliquely inwardly. A rectangular lithium ion secondary battery produced in the same manner as in Example 4 was designated as Example 4.

(Example 5)
FIG. 5 is a schematic sectional view showing the configuration of the insulator 4 used in Example 5 of the present invention.

  As shown in FIG. 5, the rectangular lithium ion produced in the same manner as in Example 1 except that the outer wall portion 4a of the insulator 4 is provided with a thin portion that expands and contracts so as to bend in the vertical direction to form an elastic portion 4d. A secondary battery was referred to as Example 5.

(Example 6)
FIG. 6 is a schematic sectional view showing the configuration of the insulator 4 used in Examples 6 to 8 of the present invention.

  As shown in FIG. 6, square lithium ions produced in the same manner as in Example 1 except that the rubber part 6 made of silicon rubber was provided on a part of the outer wall part 4 a of the insulator 4 to form the elastic part 4 d. A secondary battery was referred to as Example 6.

(Example 7)
As shown in FIG. 6, square lithium ions produced in the same manner as in Example 1 except that a rubber-like portion 6 made of polyurethane resin was provided on a part of the outer wall portion 4a of the insulator 4 to form an elastic portion 4d. A secondary battery was referred to as Example 7.

(Example 8)
As shown in FIG. 6, square lithium ions produced in the same manner as in Example 1 except that the rubber part 6 made of polyurethane elastomer is provided on a part of the outer wall part 4 a of the insulator 4 to form the elastic part 4 d. A secondary battery was referred to as Example 8.

(Comparative Example 1)
7A and 7B are schematic cross-sectional views of the main part of the battery showing the configuration of Comparative Example 1. FIG.

  After housing an electrode body 23 formed by winding a strip-like negative electrode plate and a positive electrode plate connected with lead terminals 22 through a separator in the bottomed case 21, the lead terminals 22 and the bottomed case are placed above the electrode body 23. 21. A rectangular lithium ion produced in the same manner as in Example 1 except that a frame body 24 for insulating the electrode body 23 and the electrode body 23 is disposed and a sealing body 25 to which the frame body 24 as an insulator is not attached is used. The secondary battery was referred to as Comparative Example 1.

  In Examples 1 to 8 and Comparative Example 1, 1000 square lithium ion secondary batteries were produced, and the occurrence rate of internal short circuit after the drop impact test was confirmed. The internal short-circuit occurrence rate was determined by measuring the open circuit voltage before and after the drop impact test of the prismatic lithium ion secondary battery that was almost fully charged, and determining that the open circuit voltage decreased by 100 mV or more as an internal short circuit occurrence product. In the drop impact test, a resin tray capable of storing 200 prismatic lithium ion secondary batteries prepared was used, and 200 prismatic lithium ion secondary battery sealing bodies were stored in the resin tray so that the sealing body faced downward. Then, it was naturally dropped 10 times from the height of 50 cm.

  The results are shown in (Table 1).

  As can be seen from (Table 1), no internal short circuit occurred in Examples 1 to 8, but six internal short circuits occurred in Comparative Example 1. When the lead terminals 22 of the six prismatic lithium ion secondary batteries were confirmed by X-ray fluoroscopy, it was confirmed that the lead terminals 22 were deformed to a position where they contacted the inner surface of the bottomed case 21. That is, it is considered that the drop impact test caused a problem such as the floating or tilting of the frame body 24 and the lead terminal 22 and the inner side surface of the bottomed case 21 contacted to cause an internal short circuit, resulting in a decrease in open circuit voltage.

  In other words, the prismatic lithium ion secondary battery in which the frame body 24 as an insulator is not attached to the lower part of the sealing body 25 of the comparative example 1 is formed in the lead terminal 22 and the bottomed case 21 due to the float or inclination of the frame body 24. Although there is a possibility that the side surface is in contact and the internal short circuit is caused to lower the open circuit voltage, the prismatic lithium ion secondary battery produced with the configuration of the insulator 4 of Examples 1 to 8 can remarkably improve the reliability against the internal short circuit. I understood.

  According to Examples 1-8, since the insulator 4 is attached to the lower portion of the sealing body 5 and disposed in the opening of the bottomed case 1, the insulator 4 is stably disposed on the upper portion of the electrode body 3, and It is considered that since the insulator 4 is held by the sealing member 5, the insulator 4 does not tilt even when excessive impact or vibration is applied to the prismatic lithium ion secondary battery, and the deformation of the lead terminal 2 can be suppressed.

  On the other hand, in Comparative Example 1, the frame body 24 which is an insulator is not attached to the lower portion of the sealing body 25, so that the frame body 24 is not stably held in the bottomed case 21, and excessive vibration and drop impact are applied. In this case, it is considered that the inserted state of the frame body 24 has become unstable.

  Moreover, when the upper part of the electrode body 3 of the prismatic lithium ion secondary battery of Example 1 was observed by X-ray fluoroscopy, the electrode plate on the upper part of the electrode body 3 was slightly bent although it did not affect the battery characteristics. I found out. This is probably because the electrode body 3 moved in the vertical direction in the bottomed case 1 during the drop impact test, so that the bottom plate portion 4b of the insulator 4 and the upper portion of the electrode body 3 shown in FIG. Similarly, when the electrode plate on the upper part of the electrode body 3 of the prismatic lithium ion secondary batteries of Examples 2 to 8 was observed by X-ray fluoroscopy, such bending was confirmed on the electrode plate on the upper part of the electrode body 3. There wasn't. This is considered because the elastic part 4d provided in the insulator 4 absorbed the vertical movement of the electrode body 3 during the drop impact test.

  Thus, since there is an effect capable of absorbing the vertical movement of the electrode body 3 at the time of the drop impact test, the elastic portion 4d has a dimensional variation between the lots of the electrode body 3 and the bottomed case 1, the sealing body 5 and the like. It is considered that there is an effect of absorbing a variation in positioning with the opening of the bottomed case 1.

  The insulator 4 and the sealing body 5 may be attached by attaching the insulator 4 to the lower portion of the sealing body 5 by bonding, or by providing a portion that engages with the insulator 4 at the lower portion of the sealing body 5, Alternatively, it may be attached by heat welding or integral molding with the lower part of the sealing body 5.

  The battery of the present invention can stabilize the insertion state of the insulator by attaching the insulator to the lower part of the sealing body. Therefore, the battery of the present invention is used particularly in consumer electronic devices such as laptop computers and mobile phones that may be subject to vibrations and drop impacts. It is useful for a prismatic lithium ion secondary battery.

(A) Schematic cross-sectional view of the main part of the battery showing the configuration of Example 1 of the present invention, (b) Schematic cross-sectional view of the main part of the battery showing the configuration of Example 1 of the present invention. Schematic sectional view showing the structure of the insulator used in Example 2 of the present invention Schematic sectional view showing the structure of the insulator used in Example 3 of the present invention Schematic sectional view showing the structure of the insulator used in Example 4 of the present invention Schematic sectional view showing the structure of the insulator used in Example 5 of the present invention Schematic sectional view showing the configuration of the insulator used in Examples 6 to 8 of the present invention (A) Schematic cross-sectional view of the main part of the battery showing the configuration of the conventional comparative example 1, (b) Schematic cross-sectional view of the main part of the battery showing the configuration of the conventional comparative example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bottomed case 2 Lead terminal 3 Electrode body 4 Insulator 4a Outer wall part 4b Bottom plate part 4c Hole part 4d Elastic part 5 Sealing body 6 Rubber part

Claims (9)

A bottomed case in which a belt-like positive electrode plate and a negative electrode plate connected with lead terminals are laminated or wound in a spiral shape with a separator interposed between them, and an opening in the bottomed case A battery provided with a sealing body for sealing,
The battery which attached the insulator for insulating a lead terminal, a bottomed case, or an electrode body to the lower part of the said sealing body.   The insulator includes a bottom plate portion that insulates the lead terminal from the electrode body, and an outer wall portion that is perpendicular to the bottom plate portion and is disposed on the outer peripheral surface of the bottom plate portion to insulate the bottomed case from the outer wall portion. The battery according to claim 1, wherein at least a part is provided with an elastic portion that absorbs a dimensional difference between the sealing body and the electrode body.   The battery according to claim 2, wherein the elastic part is a bellows-like part.   The battery according to claim 2, wherein the elastic portion is a corrugated portion.   The battery according to claim 2, wherein the elastic portion is a thin-walled portion.   The battery according to claim 2, wherein the elastic portion is a bent portion that bends obliquely downward and inward.   The battery according to claim 2, wherein the elastic part is a rubber part.   The battery according to claim 7, wherein the rubber part is a polyurethane resin.   The battery according to claim 8, wherein the polyurethane resin is a polyurethane elastomer.

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