JP2011159389A - Sealed flat type secondary battery - Google Patents

Abstract

An object of the present invention is to provide a rectangular or elliptical sealed flat secondary battery that is less likely to cause an internal short circuit even when subjected to a drop impact and is excellent in safety.
A flat battery outer can, a flat electrode body arranged in the battery outer body, a sealing plate 17 welded so as to seal an opening of the battery outer body, a sealing plate 17 and an electrode In a sealed flat secondary battery having a spacer 15 disposed between the body and the body, the spacer 15 is composed of a main body portion 15a constituting a central portion and end portions 15b constituting both end portions in the length direction. And the edge part 15b is formed with a shock absorbing material.
[Selection] Figure 1

Description

  The present invention relates to a sealed flat secondary battery, and more particularly to a rectangular or elliptical sealed flat secondary battery that is less likely to cause an internal short circuit even when subjected to a drop impact and is excellent in safety.

  Non-aqueous electrolyte secondary typified by lithium-ion secondary battery with high energy density and high capacity as a driving power source for portable electronic devices such as mobile phones, portable personal computers, portable music players, etc. Batteries are widely used. Among these, nonaqueous electrolyte secondary batteries using graphite particles as the negative electrode active material are widely used because of their high safety and high capacity.

  In a device in which this type of sealed battery is used, the space for storing the battery is often a square shape. Therefore, the sealed flat shape is formed by accommodating a flat electrode body in a rectangular or elliptical outer can. Secondary batteries are often used. Among such hermetically flattened secondary batteries, a schematic configuration of a prismatic nonaqueous electrolyte secondary battery will be described with reference to FIGS. 6A is a schematic view showing the inside of a conventional prismatic nonaqueous electrolyte secondary battery seen through from the surface side, and FIG. 6B is a schematic cross-sectional view taken along the line VIB-VIB in FIG. 6A. FIG. 7 is a schematic plan view of a spacer used in the prismatic nonaqueous electrolyte secondary battery shown in FIG.

  This non-aqueous electrolyte secondary battery 50 has a flat wound electrode body 13 in which a positive electrode plate having a positive electrode tab 11 and a negative electrode plate having a negative electrode tab 12 are wound through a separator. The wound electrode body 13 is accommodated in a rectangular battery outer can 14. A spacer 15 made of an insulating material that contributes to positioning of the spirally wound electrode body 13 in the battery outer can 14 is disposed above the flat spirally wound electrode body 13, and an opening of the rectangular battery outer can 14 is further provided. The sealing plate 17 having the insulating plate 26 formed on the inner surface is fitted, and the fitting portion between the rectangular battery outer can 14 and the sealing plate 17 is welded and sealed, for example, by laser welding.

  From the wound electrode body 13, the positive electrode tab 11 and the negative electrode tab 12 protrude in the same direction (upward in FIGS. 6A and 6B), and the negative electrode tab 12 has a slit-like opening 18 formed in the spacer 15 (FIG. 7) and is connected to a negative electrode current collecting tab (not shown) on the insulating plate 26, and the negative electrode current collecting tab is electrically connected to the negative electrode terminal 19. Further, the positive electrode tab 11 is passed between the spacer 15 and the battery outer can 14, a bent portion 11 ′ (see FIG. 6B) is formed between the spacer 15 and the insulating plate 26, and the end is the battery outer can. 14 and the sealing plate 17 and is welded integrally with the battery outer can 14 and the sealing plate 17. It should be noted that the bent portion 11 ′ of the positive electrode tab 11 causes the impact on the positive electrode tab 11 even when the wound electrode body 13 moves inside the battery outer can 14 when an impact is applied to the nonaqueous electrolyte secondary battery 50. It is formed to absorb.

  The spacer 15 of the nonaqueous electrolyte secondary battery 50 is made of a crystalline resin such as polypropylene or polyethylene, or other resin or rubber, and is usually formed in a flat shape along the inner surface of the battery outer can 14. However, it may be formed in a cylindrical shape or a rib (see Patent Documents 1 and 2 below). The main role of the spacer 15 is to prevent the wound electrode body 13 from being pushed down and displaced upward, and is formed for electrical insulation between the positive electrode tab 11 and the wound electrode body 13. Is done. An opening 20 (see FIG. 7) opposite to the slit-shaped opening 18 through which the negative electrode tab 12 of the spacer 15 passes is a nonaqueous electrolyte solution in the wound electrode body 13 when the nonaqueous electrolyte solution is injected. It is formed for the purpose of accelerating the liquid injection property so that the time required for penetration of the liquid becomes shorter. In some cases, the positive electrode tab 11 and the negative electrode tab 12 are arranged in reverse.

JP-A-11-025993 JP 2006-80064 A

  Since the rectangular sealed battery as described above can reduce the thickness of the spacer 15 and the insulating plate 26, the wound electrode disposed in the battery outer can 14 after ensuring necessary electrical insulation. The volume occupied by the body 13 can be increased, and the battery capacity per unit volume can be increased.

  In recent years, however, square and elliptical sealed flat secondary batteries have been increased in capacity and size, and when these batteries are processed into battery packs to be inserted into portable electronic devices, the packaging thereof However, there is an increasing tendency for simplification, such as simply wrapping a label around a battery outer can. When such a conventional rectangular or elliptical sealed flat secondary battery receives an excessive drop impact from the sealing plate side to the corner portion, this impact is applied to the electrode body through the insulating plate and the spacer. Deformation at the electrode body corner is increased, and in some cases, the battery voltage may decrease due to an internal short circuit. Such a phenomenon also occurs in a rectangular or elliptical sealed flat secondary battery having an insulating plate or spacer provided with ribs as described above.

  The inventors examined the movement of each component when receiving an excessive drop impact from the side of the sealing plate to the corner, and when receiving the drop impact, the wound electrode body positioned at the corner is Although it collides with the spacer due to inertia, it has been found that the conventional spacer is rigid and difficult to bend, so that the wound electrode body is crushed at the collision point between the wound electrode body and the spacer.

  The present invention has been made in view of the above-described problems of the prior art, and its object is to reduce the impact of a drop by changing the configuration of the spacer in a rectangular or elliptical sealed flat secondary battery. It is an object of the present invention to provide a rectangular or elliptical sealed flat secondary battery that is less likely to cause an internal short circuit even if it is subjected to, and is excellent in safety.

In order to achieve the above object, the sealed flat secondary battery of the present invention comprises:
A flat battery outer can,
A flat electrode body disposed in the battery casing;
A sealing plate welded so as to seal the opening of the battery exterior body;
In a sealed flat secondary battery provided with a spacer disposed between the sealing plate and the electrode body,
The spacer is composed of a main body part constituting a central part and end parts constituting both end parts in the length direction,
The end portion is formed of a cushioning material.

  When a sealed flat secondary battery is subjected to a drop impact, both end sides in the length direction are easily deformed, and in particular, the corner portion is easily deformed, but the center portion and the side surface portion in the length direction are in the length direction. It has the property of being harder to deform than both ends. Since the spacer used in the present invention employs shock absorbing cushioning material at both end portions in the length direction, the portions where these end portions were formed received external shocks. At that time, the shock is easily absorbed. Therefore, in the sealed flat secondary battery of the present invention, even if a drop impact is received from the corner side of the sealing plate, the impact transmitted to the flat electrode body is reduced, and the flat electrode body is not easily deformed. Therefore, the battery voltage is less likely to be lowered even when subjected to a drop impact as compared with the conventional sealed flat secondary battery.

  The flat electrode body that can be used in the sealed flat secondary battery of the present invention is a flat electrode body that is produced by crushing a wound electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween. A flat wound electrode formed by laminating a plurality of positive electrode plates and a plurality of negative electrode plates with a separator interposed therebetween may be used. Further, the shape of the outer can of the sealed flat secondary battery may include a rectangular cross section, a square square, an oval, an ellipse, and the like. Further, the sealed flat secondary battery of the present invention may be not only a non-aqueous electrolyte secondary battery but also an aqueous electrolyte secondary battery such as a nickel-hydrogen storage battery.

  Further, in the sealed flat secondary battery of the present invention, the main body portion and the end portion of the spacer are formed separately, and are integrated by an insulating tape wound around the side surface of the spacer. It is preferable.

  It is difficult to integrally form a portion (hereinafter, referred to as a “rigid portion”) that is made of the same material and does not have buffering properties and a portion that has buffering properties. Moreover, even if a thin plate-like rigid member and a cushioning member are bonded to each other on the side surfaces, the bonding strength is very weak. The spacer used in the sealed flat secondary battery of the present invention uses a body part and an end part separately formed, but the body part and the end part are insulated on the side surface. Integrated with tape. As a result, the main body and the end are fixed integrally, and the end can absorb the impact satisfactorily when subjected to a drop impact, so that the above-described effect can be achieved better.

  In the sealed flat secondary battery of the present invention, it is preferable that the insulating tape is wound around the upper end portion of the electrode body in the sealing plate direction at the same time.

  With such a configuration, since the electrode body and the spacer can be fixed integrally with the insulating tape in a stable state, the positional relationship between the spacer and the electrode body is not easily displaced even when subjected to a drop impact. Therefore, according to the sealed flat secondary battery of the present invention, it is possible to satisfactorily absorb the drop impact by the end portion of the spacer, the deformation of the electrode body is further suppressed, and the battery voltage is hardly lowered. In the sealed flat secondary battery of the present invention, the insulating tape in which an adhesive or adhesive is applied on one side as an insulating tape, or a simple adhesive tape is used to separate the end of winding separately from the adhesive tape or Those fixed with an adhesive may be used.

  In the sealed flat secondary battery of the present invention, the main body portion and the end portion of the spacer are formed separately, and both are fixed and integrated on the surface of the insulating tape. Can be.

  According to the sealed flat secondary battery of the present invention, the main body part and the end part can be integrated by simply fixing the main body part and the end part of the spacer on the surface of the insulating tape. Become. In the sealed flat secondary battery of the present invention, as the insulating tape, an insulating tape coated with an adhesive or an adhesive on one side or a heat-welding insulating tape can be used. In addition, it is also possible to use a spacer in which the main body portion and the end portion of the spacer are fixed with an adhesive using a simple insulating tape.

  Moreover, in the sealed flat secondary battery of the present invention, the end portion is based on the entire center of the spacer as a base point, and is more than 70 to 90% of the distance from the center to the end portion in the length direction. It is preferably formed on the end side.

  If the distance from the center of the spacer to the opposing part (gap) between the main body part and the end part is within this range, the end part on which the spacer cushioning material is formed is the electrode body corner part, It is preferable because it covers a portion that is easily deformed. If it exceeds 90% of the distance from the center to the end in the length direction, the end where the spacer cushioning material is formed cannot cover all the places where the impact was dropped. The effect of forming may become difficult to appear. Similarly, if it is less than 70%, it is difficult to ensure the rigidity of the spacer, and there is a risk that the original functions such as positioning of the electrode body as a spacer and prevention of upper displacement may be lost.

  Further, in the sealed flat secondary battery of the present invention, the end is formed of polyisoprene, styrene / butadiene rubber, polyisobutylene, nitrile rubber, hydrogenated nitrile rubber, epichlorolyl hydrin rubber, chloroprene rubber, silicone rubber, It is preferably formed of any one of fluorine rubber, acrylic rubber, and ethylene propylene rubber.

  Since these rubber materials have good buffering properties, the effects of the present invention can be achieved better.

  In the sealed flat secondary battery of the present invention, an insulating plate is disposed between the sealing plate and the spacer, and the length of the spacer in the length direction is the length of the insulating plate in the length direction. Longer than this is preferable.

  In the sealed flat secondary battery of the present invention, an insulating plate is disposed between the sealing plate and the spacer, and the length in the length direction of the spacer is longer than the length in the length direction of the insulating plate. When the corner portion of the battery is subjected to a drop impact, the electrode body does not directly contact the insulating plate and collides only with the cushioning material at the end portion. Therefore, according to the sealed flat type secondary battery of the present invention, the impact transmitted to the flat type electrode body is alleviated, and the flat type electrode body is hardly deformed.

  Moreover, in the sealed flat secondary battery of the present invention, it is preferable that the sealing plate and the insulating plate are integrally fixed by a terminal plate electrically connected to the electrode body.

  According to the sealed flat secondary battery of the present invention, the electrical insulation between the terminal plate and the sealing plate can be easily maintained, and the electrical connection between the terminal plate and the electrode body can be easily performed. In addition, since the electrical connection between the terminal plate and the electrode body can be easily insulated simply by abutting the spacer against the insulating plate, it is easy to manufacture and has a highly reliable sealed flat secondary A battery is obtained.

FIG. 1A is a plan view of a sealing plate of the prismatic nonaqueous electrolyte secondary battery of the embodiment, and FIG. 1B is a plan view of the spacer. 2A is a sectional view taken along line IIA-IIA in FIG. 1A, FIG. 2B is a sectional view taken along line IIB-IIB in FIG. 1B, and FIG. 2C is a sectional view taken along line IIA-IIA in FIG. FIG. 2D is a plan view of the electrode body when the exterior can is seen through. FIG. 3A is an exploded plan view of the sealing plate and the insulating plate portion of the embodiment, and FIG. 3B is an exploded sectional view of the same. It is a schematic cross section at the time of giving a drop impact to the corner | angular part of a square nonaqueous electrolyte. It is sectional drawing corresponding to FIG. 2B of the spacer of a modification. FIG. 6A is a schematic view showing the inside of a conventional prismatic nonaqueous electrolyte secondary battery seen through from the surface side, and FIG. 6B is a schematic cross-sectional view taken along the line VIB-VIB of FIG. 6A. FIG. 7 is a schematic plan view of a spacer used in the prismatic nonaqueous electrolyte secondary battery shown in FIG. 6.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, the embodiment shown below shows an example of a rectangular nonaqueous electrolyte secondary battery as a sealed flat secondary battery for embodying the technical idea of the present invention. The present invention is not intended to be specified in any form, and the present invention can be equally applied to various modifications without departing from the technical concept shown in the claims.

[Embodiment]
First, a prismatic nonaqueous electrolyte secondary battery according to an embodiment will be described with reference to FIGS. However, in FIGS. 1 to 3, the same components as those of the conventional rectangular nonaqueous electrolyte secondary battery 50 shown in FIG. 1 to 3, a part of the configuration of the prismatic nonaqueous electrolyte secondary battery 50 shown in FIG. 6 is omitted. Further, in this specification, “upper side (upper)” indicates the terminal side, and “lower side (lower)” indicates the flat wound electrode body side.

  This rectangular nonaqueous electrolyte secondary battery 10 has a flat wound electrode body 13 in which a positive electrode plate having a positive electrode tab and a negative electrode plate having a negative electrode tab are wound through a separator (both not shown). (See FIG. 2C). The flat wound electrode body 13 is accommodated in a rectangular battery outer can 14. A spacer 15 made of an insulating material is disposed on the flat wound electrode body 13, and a sealing plate 17 in which an insulating plate 26 is formed below the opening of the rectangular battery outer can 14. Are fitted, and the fitting portion between the rectangular battery outer can 14 and the sealing plate 17 is welded and sealed, for example, by laser welding.

  From this wound electrode body 13, a positive electrode tab and a negative electrode tab (both not shown) protrude in the same direction, and the negative electrode tab passes through a slit-shaped opening 18 (see FIG. 1B) formed in the spacer 15. The negative terminal rivet 21 penetrating the insulating plate 26 is electrically connected to the negative terminal plate 19a. The negative terminal 19 is formed by the negative terminal plate 19 a and the negative terminal rivet 21. Further, the positive electrode tab is passed between the spacer 15 and the battery outer can 14, a bent portion (not shown) is formed between the spacer 15 and the insulating plate 26, and the end is the battery outer can 14 and the sealing plate. 17 and is integrally welded to the battery outer can 14 and the sealing plate 17.

  Further, the sealing plate 17 is formed with a safety valve 22 and a non-aqueous electrolyte injection hole 23, and the non-aqueous electrolyte injection hole 23 is sealed with a sealing material (not shown). As shown in FIGS. 2A and 3B, the negative electrode terminal 19 has the negative electrode terminal plate 19 a and the gasket 24 placed on the sealing plate 17, and the terminal rivet 21 is placed from the lower side of the sealing plate 17 through the insulating plate 26. The terminal rivets 21 are integrated with each other by being inserted and crimped. Thereby, the sealing plate 17 and the insulating plate 26 are integrally formed by the negative electrode terminal plate 19 a, the gasket 24 and the terminal rivet 21. Here, a depression is formed in the insulating plate 26 so that the terminal rivet 21 portion does not protrude toward the flat wound electrode body 13 side.

  On the other hand, as shown in FIGS. 1B and 2B, the spacer 15 has a main body portion 15a occupying a central portion and end portions 15b formed at both ends. In this example, the main body portion 15a is formed of polypropylene that ensures a certain degree of rigidity. On the other hand, the end 15b is made of, for example, styrene butadiene rubber in order to impart shock absorption.

  As the end 15b, in addition to styrene butadiene rubber, polyisoprene, polyisobutylene, nitrile rubber, hydrogenated nitrile rubber, epichlorolyl hydrin rubber, chloroprene rubber, silicone rubber, fluorine rubber, acrylic rubber, ethylene propylene rubber, etc. A material having a certain degree of elasticity (shock absorption) may be used.

  1B and 2B show an example in which the main body portion 15a and the end portion 15b are arranged in close contact with each other at the joint portion 25, but a slight gap may be formed. However, since the main body portion 15a and the end portion 15b are made of different materials, it is difficult to integrally form both of them, and it is difficult to firmly fix the side surfaces even if they are closely fixed with an adhesive. is there.

  In the rectangular nonaqueous electrolyte secondary battery 10 of the present embodiment, the main body portion 15 a and the end portion 15 b are positioned above the wound electrode body 13, and the negative electrode current collecting tab passes through the slit-shaped opening 18. After that, as shown in FIGS. 2C and 2D, they are attached by, for example, winding the periphery together with the periphery of the upper end portion of the wound electrode body 13 with an insulating tape 16 with an adhesive. . By configuring in this way, the main body 15 a and the end 15 b constituting the spacer 15 are integrated and fixed above the wound electrode body 13.

  The insulating tape 16 is not only an insulating tape having an adhesive material or adhesive applied on one side, but also a simple insulating tape and the winding end is separately fixed with an adhesive tape or adhesive. May be used.

Moreover, the specific manufacturing method of the non-aqueous electrolyte secondary battery as a flat wound electrode body and a square sealed battery used in the embodiment is as follows.
[Production of positive electrode]
The positive electrode plate was produced as follows. First, lithium cobalt oxide (LiCoO ₂ ) powder as a positive electrode active material, acetylene black as a positive electrode conductive agent, and polyvinylidene fluoride (PVdF) powder, positive electrode active material: acetylene black: PVdF = 94: 3: 3 Was added to and kneaded with N-methyl-2-pyrrolidone (NMP) at a mass ratio of This slurry was applied to both surfaces of a positive electrode current collector made of aluminum foil having a thickness of 15 μm by a doctor blade method and then dried to form a positive electrode active material layer on both surfaces of the positive electrode current collector. Then, it compressed using the compression roller and produced the positive electrode. Then, a substantially U-shaped cut was made in the exposed portion of the positive electrode current collector to form a portion that would become a positive electrode tab.

[Production of negative electrode]
Dispersion of graphite powder as a negative electrode active material and styrene butadiene rubber (SBR) (styrene: butadiene = 1: 1) in water, and further adding carboxymethyl cellulose (CMC) as a thickener An active material mixture slurry was prepared. In addition, the dry mass ratio of this negative electrode active material mixture slurry was prepared so that it might become graphite: SBR: CMC = 95: 3: 2. This negative electrode active material mixture slurry was applied to both sides of a copper foil negative electrode current collector made of copper foil having a thickness of 8 μm by the doctor blade method, dried, and then compressed by a compression roller to produce a negative electrode. And the negative electrode tab made from nickel metal was welded to the exposed part of this negative electrode collector.

[Preparation of non-aqueous electrolyte]
1 mol / liter of LiPF ₆ was dissolved in a mixed solvent composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) (volume ratio of EC: EMC: DEC = 30: 50: 20). A water electrolyte was prepared.

[Production of winding electrode body]
Using the above positive electrode and negative electrode, the positive electrode tab and the negative electrode tab are led out in the same direction, and the positive electrode tab is on the outside, and a separator is interposed between the two electrodes, and then wound in a cylindrical shape. A flat wound electrode body was obtained by crushing.

[Production of spacer]
Here, as shown in FIG. 1B, the distance from the center point P of the body portion 15a of the spacer 15 to both ends of the end portion (buffer material) 15b is L, and the center point P of the body portion 15a and the end portion 15b. The length in the width direction to the corresponding position is W, and the substantial thickness of the spacer 15 is t (see FIG. 2B). The main body 15a of the spacer 15 used in the embodiment is made of polypropylene having a short side width of 4.2 mm, a length of 25 mm, and a thickness of 0.8 mm.

  Then, as shown in FIG. 1B, from the cushioning material, the joint portion 25 is formed so as not to generate a gap at a position 12.5 mm away from the center point of the main body portion 15a of the spacer 15 on both ends. What arranged the edge part 15b used is used. That is, the end portion 15b has a semicircular shape at one end, but is made of styrene butadiene rubber having a width = 4.2 mm, a length of 3.8 mm, and a thickness of 0.8 mm. Therefore, the spacer 15 used in the embodiment is W = 2.1 mm, L = 16.3 mm, t = 0.8 mm, and the position of the joint portion 25 is about 0.8L. It should be noted that a slight gap may be generated in the joint portion 25.

  In this way, the negative electrode tab of the flat wound electrode body 13 is passed through the opening 18 on one side of the main body portion 15a of the spacer 15, and the main body portion 15a and the end portion 15b, which are constituent elements of the spacer 15, are wound. It is placed on the upper side of the electrode body 13. Thereafter, the spacer 15 and the wound electrode are wound by simultaneously winding the side surfaces of the main body 15a and the end 15b, which are constituent elements of the spacer 15, and a part of the upper side of the wound electrode body 13 with the insulating tape 16. The body 13 is fixed integrally.

  Then, the negative electrode tab is welded to the terminal rivet 21 of the negative electrode terminal 19 integrated with the sealing plate 17 and the insulating plate 26 manufactured as described above. Subsequently, it arrange | positions so that the insulating plate 26 may contact | abut to the spacer 15 formed above the winding electrode body 13. FIG. The spacer 15 and the insulating plate 26 may be integrated by fitting the main body 15 a of the spacer 15 to the insulating plate 26.

  Then, the flat wound electrode body 13 is inserted into the battery outer can 14, and the positive electrode tab passes between the spacer 15 and the battery outer can 14 and is bent between the spacer 15 and the insulating plate 26. (Not shown) is formed and led out so that the end portion is sandwiched between the battery outer can 14 and the sealing plate 17. Further, the sealing plate 17 is fitted into the opening of the battery outer can 14, and the battery outer can 14 and the sealing plate 17 are integrated with each other by, for example, laser welding of the fitting portion.

  Thereafter, a predetermined amount of non-aqueous electrolyte was injected from the electrolyte solution injection hole 23, and the electrolyte solution injection hole was sealed to obtain the rectangular non-aqueous electrolyte secondary battery of the embodiment. In addition, the concrete size of the produced square nonaqueous electrolyte secondary battery is short side width: 5.2 mm, long side length: 34 mm, and height: 50 mm.

  In addition, the prismatic nonaqueous electrolyte secondary battery of the comparative example shown below corresponds to the conventional example shown in FIG. 7 as the spacer 15, that is, uses the one that is integrally made of polypropylene as a whole. It is.

[Drop test]
A battery pack having a protection circuit necessary for each of the prismatic nonaqueous electrolyte secondary batteries of the embodiment and the comparative example obtained as described above was manufactured, and 10 pieces of these battery packs were used, as shown in FIG. 4A. As described above, a drop test was performed. In the drop test, the negative electrode terminal (top) of the battery is dropped downward on a steel plate 30 with an insulation coating from a height of 1.8 m, and the voltage of the battery pack is measured each time it falls. Then, the number of drops when the voltage drop occurred was measured, and this operation was repeated 200 times for those for which no battery voltage drop was observed. The results are summarized in Table 1.

[Table 1]
Embodiment 10/10 cell 200 times No abnormality Comparative example 5/10 cell 200 times No abnormality
5/10 cell voltage drop
(156 times, 161 times, 171 times, 172 times, 189 times)

  From the results shown in Table 1 above, according to the battery of the embodiment, the battery voltage decrease tendency is not recognized even in the excessive drop test, and the reliability is higher than the battery of the comparative example corresponding to the conventional one. It was confirmed that The reason why such a phenomenon occurs is that, for example, as shown in FIG. 4B, when a drop impact is applied, the corner portion 13a of the flat wound electrode body 13 is deformed. At this time, the spacer 15 made of a cushioning material is deformed. It is estimated that excessive deformation of the corner portion 13a does not occur when the end portion 15b absorbs part of the impact.

  As shown in FIG. 1B, the spacer 15 of the embodiment has a joint portion 25 so that no gap is formed between the main portion 15a and the end portion 15b on both ends in the length direction from the center point P. However, a slight gap may be formed in the joint portion 25. Moreover, although the spacer 15 of the embodiment has shown an example in which the distance from the center of the spacer to the joint portion 25 is about 0.8 L (80%), the distance from the center point P of the spacer 15 to the joint portion 25 is shown. If the distance is in the range of 0.7 L to 0.9 L (70% to 90%), the same effect as the battery of the embodiment is exhibited.

Further, in the embodiment, the battery outer can 14 of the square nonaqueous electrolyte secondary battery 10 is the positive electrode and the terminal is the negative electrode, but this arrangement may be reversed.

[Modification]
In the rectangular nonaqueous electrolyte secondary battery 10 of the above embodiment, an example in which the main body portion 15a and the end portion 15b of the spacer 15 are fixed by winding the insulating tape 16 around the upper end portion of the wound electrode body 13 is shown. . This is because the main body portion 15a and the end portion 15b of the spacer 15 are separated, and even if the side end portions of the main body portion 15a and the end portion 15b are fixed with an adhesive, they are easily separated. is there.

  Therefore, a modified example in which the main body portion 15a and the end portion 15b of the spacer 15 are integrated by being fixed on the insulating tape 16a will be described with reference to FIG. FIG. 5 is a cross-sectional view corresponding to FIG. 2B of the spacer 15 ′ of the modification. In FIG. 5, the same components as those of the spacer 15 of the embodiment shown in FIG. 2B are given the same reference numerals, and detailed descriptions thereof are omitted.

  The spacer 15 ′ of this modification uses a surface in which an adhesive layer 16 b is formed on the surface of the insulating tape 16 a, and the main body portion 15 a and the end portion 15 b are bonded to the surface of the adhesive layer 16 b. It is positioned and fixed so that the portion 25 is generated. However, even in this example, a slight gap may be generated in the joint portion 25. In the spacer 15 ′ of this modified example, it is necessary to form the openings 18 and 20 also in the insulating tape 16a. However, since the insulating tape 16a is flexible, it can be easily formed by cutting or punching.

  As this insulating tape 16a, a heat-weldable insulating tape can be used in addition to the one coated with an adhesive or adhesive on one side, and further, the spacer main body can be formed using a simple insulating tape. What fixed the part 15a and the edge part 15b with the adhesive agent can also be used.

  If the spacer 15 ′ of such a modification is used, the spacer 15 ′ can be handled as a separate component from the wound electrode body 13, so that the sealed flat secondary battery of the conventional example shown in FIG. In this case, it can be produced in the same manner, and the same effect as in the case of the sealed flat secondary battery 10 of the embodiment described above can be obtained.

  In the above-described embodiment and modification, an example in which a rectangular non-aqueous electrolyte secondary battery using a flat wound electrode body is used as a sealed flat secondary battery is shown, but an elliptical wound electrode body is used. However, the present invention is also applicable to a non-aqueous electrolyte secondary battery using a stacked electrode body in which a positive electrode plate and a negative electrode plate are sequentially stacked with an insulating film interposed therebetween. In addition, as the shape of the outer can of the sealed flat secondary battery, the opening may include a rectangular shape, a square shape, an oval shape, an oval shape, etc., and the rectangular shape may have four corners curved. Furthermore, although the example applied to the non-aqueous electrolyte secondary battery was shown in the embodiment, the present invention can also be applied to an aqueous electrolyte secondary battery such as a nickel-hydrogen storage battery.

  DESCRIPTION OF SYMBOLS 10, 50 ... Square nonaqueous electrolyte secondary battery 11 ... Positive electrode tab 12 ... Negative electrode tab 13a ... Corner part 13 ... Winding electrode body 14 ... Battery exterior can 15, 15 '... Spacer 15a ... Main-body part 15b ... End part (buffer) Materials) 16, 16a ... Insulating tape 16b ... Adhesive layer 17 ... Sealing plate 18 ... Opening 19 ... Negative electrode terminal 19a ... Negative electrode terminal plate 20 ... Opening 21 ... Negative electrode terminal rivet 22 ... Safety valve 23 ... Non-aqueous electrolyte injection hole 24 ... Gasket 25 ... Junction 26 ... Insulating plate 30 ... Steel plate P ... Center

Claims (8)

A flat battery outer can,
A flat electrode body disposed in the battery case;
A sealing plate welded so as to seal the opening of the battery exterior body;
In a sealed flat secondary battery provided with a spacer disposed between the sealing plate and the electrode body,
The spacer is composed of a main body part constituting a central part and end parts constituting both end parts in the length direction,
The end portion is formed of a buffer material, and is a sealed flat secondary battery.   2. The hermetic seal according to claim 1, wherein the main body portion and the end portion of the spacer are separately formed and integrated by an insulating tape wound around a side surface of the spacer. Flat secondary battery.   3. The sealed flat secondary battery according to claim 2, wherein the insulating tape is wound around an upper end portion of the electrode body in the sealing plate direction at the same time.   2. The hermetic flat according to claim 1, wherein the main body portion and the end portion of the spacer are separately formed, and both are fixed and integrated on the surface of the insulating tape. Type secondary battery.   The said edge part is formed in the edge part side rather than the position of 70 to 90% of the distance from the said center to the edge part of a length direction on the basis of the whole center of the said spacer. Item 2. The sealed flat secondary battery according to Item 1.   The end is formed of any of polyisoprene, styrene / butadiene rubber, polyisobutylene, nitrile rubber, hydrogenated nitrile rubber, epichlorolyl hydrin rubber, chloroprene rubber, silicone rubber, fluorine rubber, acrylic rubber, and ethylene propylene rubber. The sealed flat secondary battery according to claim 1, wherein An insulating plate is disposed between the sealing plate and the spacer,
2. The sealed flat secondary battery according to claim 1, wherein a length of the spacer in a length direction is longer than a length of the insulating plate in a length direction.   The sealed flat secondary according to any one of claims 1 to 6, wherein the sealing plate and the insulating plate are integrally fixed by a terminal plate electrically connected to the electrode body. battery.

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