JP4179762B2 - Sealed battery provided with film-shaped exterior body and method for manufacturing the same - Google Patents

Description

【００３１】
表１に示すように、実施例１〜３のものでは、比較例１のものに対してタブ切れ数が少ない。特に、実施例１，２では、タブ切れは発生しなかった。
次に、漏液数については、比較例２のものでは抜き取った１０セルのうち９セルで漏液が確認されたのに対して、実施例１〜３のものでは確認されなかった。これは、比較例１のものでは貼付部分を形成する際に溶着樹脂の流れが一方向となってタブの切断を生じ、また、比較例２のものでは未溶着部が発生することから漏液を生じるのに対して、実施例１〜３のものでは、貼付部分の逃がし部において未溶着部を生じることがないとともに、貼付部分を形成する際の溶着樹脂の流れが分散されたことによると考えられる。
【００３２】
中でも、実施例１及び２のように逃がし部の幅狭部分が貼付部分の外縁部と内縁部との中間にあるものが特に有効である。
【００３３】
【発明の効果】
以上のように、本発明のフィルム状外装体を備える密閉電池では、外装体の外周部における逃がし部を、幅狭部分と幅広部分を併せ持つ形状とすることによって、逃がし部におけるシール性を確保するとともに、外装体の貼付部分を形成する際にタブの切断の発生を抑制することが出来る。
【００３４】
また、本発明のフィルム状外装体を備える密閉電池の製造方法では、密封工程において、各タブに帯板状の溶着樹脂を重ね合わせた状態で、タブの幅方向に対して幅広部分と幅狭部分を併せ持つ形状の溝が形成された金型を用いて、外装体の外周部を加熱しながら加圧することにより、前記外周部における逃がし部の少なくとも一を形成するので、外周部の貼付部分におけるシール性を確保するとともにタブの切断を抑制することが出来る。
【００３５】
従って、本発明は、フィルム状外装体を備える密閉電池の製造上において歩留まりを向上させるのに有効であるとともに、電池の信頼性を向上させるのに有効な技術である。
【図面の簡単な説明】
【図１】本発明の実施の形態にかかるラミネート型電池の斜視（一部断面）図である。
【図２】図１のＡ−Ａ矢視断面図である。
【図３】本発明の実施の形態にかかるラミネート型電池の製造における密封工程を示す概略図である。
【図４】図１のＢ−Ｂ矢視断面図である。
【図５】変形例としての逃がし部の形状を示す図である。
【図６】変形例としての逃がし部の形状を示す図である。
【図７】貼付部分を形成する際の溶着樹脂の流れを概念的に示す図である。
【図８】従来のラミネート型電池の斜視（一部断面）図である。
【図９】従来の逃がし部の形状を示す図である。
【符号の説明】
１ ラミネート型電池
１０ 外装体
１１ａ，１１ｂ 貼付部分における逃がし部
２１ａ，２１ｂ タブ
３０ａ，３０ｂ 溶着樹脂
５００ 金型
５０１ 金型の溝領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed battery including a fill-like exterior body and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, with the spread of small and light portable devices, sealed batteries equipped with a film-like exterior body that is suitable for being thin and capable of being reduced in weight have become popular. A typical example of such a sealed battery is a laminated battery using a laminate sheet as an outer package.
[0003]
The structure of the laminate type battery will be described with reference to FIG. FIG. 8 is a perspective view (partially cross-sectional view) of the laminated battery.
As shown in FIG. 8, the laminate type battery has a structure in which an electrode body 70 is sealed inside an exterior body 60 formed of a laminate sheet in which an aluminum layer and a resin layer are laminated. Reference numeral 60t in the figure is a pasted portion. Further, tabs 71 a and 71 b are provided on the positive electrode plate and the negative electrode plate forming the electrode body 70, and extend to the outside of the exterior body 60 across the pasting portion 60 t and generated by the electrode body 70. Can be taken out.
[0004]
By the way, the affixing portion 60t is formed by pressurizing the laminated sheet of the portion while heating with a mold, and the mold used has a groove in a region where the tabs 71a and 71b cross. In the region where the tabs 71a and 71b cross in the pasting portion 60t, relief portions 61a and 61b are formed for the laminate sheet to escape the inner edge of the outer package 60 in the thickness direction and width direction of the tabs 71a and 71b.
[0005]
Further, when forming the affixed portion 60t, the tabs 71a and 71b are made in a state where band-like welding resins 80a and 80b are overlapped. As a result, between the escape portions 61a and 61b and the tabs 71a and 71b in the pasting portion 60t, the welding resins 80a and 80b are filled and sealed.
The shape of the relief portions 61a and 61b (the shape in the direction of the arrow from the main surface side of the exterior body 60) is a rectangular shape wider than the tabs 71a and 71b, as shown in FIG. As the belt-like welding resins 80a and 80b inserted as fillers, those having a width wider than the escape portions 61a and 61b are used. Thereby, airtightness is maintained between the tabs 71a and 71b and the relief portions 61a and 61b in the pasting portion 60t.
[0006]
[Problems to be solved by the invention]
However, in the laminate type battery having the above-described structure, there is a problem in that the tabs 71a and 71b may be cut when the pasting portion 60t is formed, resulting in poor manufacturing yield.
It is considered that the tab is cut when the pasting portion 60t is formed as described above due to the following causes.
[0007]
The width of the relief portions 61a and 61b in the pasting portion 60t, that is, the groove width of the mold used when welding the pasting portion 60t is slightly larger than the width of the tabs 71a and 71b. Therefore, when forming the affixing portion 60t, a narrow gap is formed between the mold groove and the tab along the extending direction of the tabs 71a and 71b, and the welding resin is melted by heating. 80a and 80b flow at high speed along the gap. The flow of the welding resins 80a and 80b is considered to pull the tabs 71a and 71b in the extending direction. Thereby, in the laminate type battery, a thin tab is used, so that the tab can be easily cut only by applying a tensile force due to the flow of the welding resins 80a and 80b.
[0008]
In particular, since aluminum (Al) is generally used as the material for the tab 71a on the positive electrode side, the strength is lower than the tab 71b on the negative electrode side where nickel (Ni) is used, and the tab is likely to be cut.
Considering only such a problem from the viewpoint of preventing the tab from being cut, as shown in FIG. 9B, by taking the width of the relief portions 61a and 61b considerably wider than the tabs 71a and 71b, This can be solved by widening the gap between the groove and tab of the mold.
[0009]
However, in the case where the gap between the tabs 71a and 71b and the escape portions 61a and 61b is wide, an unwelded portion in which the weld resins 80a and 80b are not filled in the escape portions 61a and 61b, so-called through-holes, is generated. It tends to be defective.
In view of the above problems, an object of the present invention is to provide a sealed battery including a film-shaped outer package without a tab break while maintaining the airtightness of the battery, and a method for manufacturing the sealed battery.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an electrode body in which a positive electrode plate and a negative electrode plate are opposed to each other is sealed inside an outer package body made of a sheet material, and the outer package body is formed from each of the positive electrode plate and the negative electrode plate. The tab extends across the outer peripheral portion of the outer peripheral portion, and in the region of the outer peripheral portion where the tab crosses, a relief portion is formed to escape the inner edge of the exterior body in the thickness direction and the width direction of the tab. A sealed battery including a film-shaped outer package configured to be filled and sealed with a welding resin, wherein at least one of the escape portions has a shape having both a wide portion and a narrow portion with respect to the width direction of the tab. It is characterized by being.
[0011]
In addition, the present invention provides an electrode body manufacturing process for manufacturing an electrode body in which a positive electrode plate and a negative electrode plate are arranged to face each other, and a tab is provided on each of the positive electrode plate and the negative electrode plate, and an exterior in which the tab is made of a sheet material. A sealing step of wrapping the electrode body so as to extend across the outer periphery of the body, and welding the outer periphery to seal the electrode body inside the exterior body, A film-like exterior that forms a relief portion for escaping the inner edge of the exterior body in the thickness direction and the width direction of the tab in the region where the tab crosses in the outer peripheral portion of the body and fills the relief portion with a welding resin and seals it A method of manufacturing a sealed battery including a body, wherein in the sealing step, a strip plate-shaped welding resin is overlapped on each tab, and a shape having both a wide portion and a narrow portion with respect to the width direction of the tab. Use a mold with grooves Te, by applying pressure while heating the outer peripheral portion of the outer body, and forming at least one relief portion of the outer peripheral portion.
[0012]
According to the present invention having the features as described above, the relief portion in the outer peripheral portion of the exterior body has both a narrow portion and a wide portion, so that when the outer peripheral portion is welded, the clearance between the mold groove and the tab is Even if the narrow gap is partially formed along the extending direction of the tab, it is not continuously formed. Therefore, the force that pulls the tab in the extending direction caused by the welding resin melted by heating during welding flowing through the gap between the groove and the tab of the mold is reduced as compared with the conventional case. On the other hand, the narrow portion of the escape portion of the outer peripheral portion is reliably sealed because it is filled with the welding resin.
[0013]
Here, it is preferable that the narrow portion is provided in a central portion in the extending direction of the tab in the escape portion. This is because if the narrow portion is set in this way, the direction in which the welding resin flows in the wide portion is dispersed not only in the extending direction of the tab but also in the width direction.
As the overall shape of the escape portion, it is desirable that the shape as viewed from the main surface side of the exterior body is a drum shape.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective (partly cross-sectional) view of a laminated battery according to this embodiment, and FIG. 2 is a cross-sectional view taken along the line AA in FIG.
The overall configuration of the laminate type battery (hereinafter simply referred to as “battery”) 1 and the manufacturing method thereof will be described with reference to FIGS.
[0015]
The battery 1 is a wound body that is flatly compressed inside an exterior body 10 formed by molding a sheet body made of an aluminum laminate sheet (a sheet of aluminum foil covered with a PP layer or a PE layer) into a rectangular cylindrical shape. In which an electrode body 20 impregnated with an electrolytic solution is housed. As shown in FIG. 2, the positive electrode plate 201 and the negative electrode plate 202 in the electrode body 20 are disposed to face each other with a separator 203 interposed therebetween.
[0016]
As shown in FIG. 1, the exterior body 10 is a three-side seal type formed by bending a single sheet body into a rectangular exterior body and welding three sides of the outer periphery thereof. is there. In FIG. 1, reference numerals 10 t and 10 s indicate the pasted portions of the three sides.
Further, in order to form external terminals, the battery 1 has a positive electrode tab 201 a made of a thin plate of aluminum (Al) on the positive electrode plate 201 and a negative electrode tab 21 b made of a thin plate of nickel (Ni) on the negative electrode plate 202. The positive electrode tab 21a and the negative electrode tab 21b are connected to each other and extend outward of the outer package 10 across the pasting portion 10t of the outer peripheral portion.
[0017]
In the production of the battery 1, the positive electrode side tab 21a and the negative electrode side tab 21b are connected to the positive electrode plate 201 and the negative electrode plate 202, respectively, and the whole is compressed flatly to produce a wound body. The laminate sheet is folded so as to be wrapped to form an exterior body, impregnated with an electrolytic solution, and the portions corresponding to the pasted portions 10t and 10s are heated and heated with a mold and welded.
(Formation of affixed portion 10t)
In the formation of the affixed portion 10t at the outer peripheral portion, as shown in FIG. 3, the laminating sheet 100 is formed using the metal mold 500 with the belt-like welding resins 30a and 30b overlaid on the tabs 21a and 21b. And pressurizing while heating. In this mold 500, a groove region 501 is provided so as to allow the thicknesses of the positive electrode tab 21a and the negative electrode tab 21b to escape in a portion corresponding to a region where the positive electrode tab 21a and the negative electrode tab 21b cross in the pasted portion 10t. Is provided.
[0018]
Here, as shown in FIG. 3, the tabs 21a and 21b have a rectangular shape with a constant width (3 mm), but the groove region 501 of the mold 500 has a narrow central portion in plan view (5. 5 mm), the width on both ends is wide (10 mm), and the whole is a drum shape.
If the pasting portion 10t is formed using the mold 500 provided with the groove region 501 in this way, the laminate sheet 100 is pushed toward the groove region 501 of the die 500 in the portion where the tabs 21a and 21b exist. It is. As a result, relief portions 11a and 11b are formed in the pasting portion 10t so that the laminate sheet 100 escapes the inner edge of the outer package 10 in the thickness direction and width direction of the tabs 21a and 21b. The shapes of the relief portions 11a and 11b are substantially the same as the shape of the groove region 501 in a plan view (a shape as viewed from the main surface side of the exterior body 10).
[0019]
The welding resins 30a and 30b are made of a resin that is melted by heating, and the shape before melting is a belt-like shape, and the width is set to a width (8 mm) slightly wider than the width of the central portion of the groove region 501. ing.
4 is a cross-sectional view of the battery 1 shown in FIG.
As shown in FIG. 4, relief portions 11a and 11b having substantially the same shape as the groove region 501 are formed in the pasting portion 10t formed by the above method so as to cross the pasting portion 10t.
[0020]
That is, the relief portions 11a and 11b have narrow portions 110a and 110b (width: 5.5 mm) near the center of the pasting portion 10t, wide portions 111a and 111b (width: 10 mm) near the inner edge, and the outside There are also wide portions 112a and 112b (width: 10 mm) near the edge.
In FIG. 4, the hatched area of the lattice pattern is an area heated and pressed by the mold 500 when the outer peripheral portion is welded, that is, an area where the laminate sheets 100 are heat-sealed. The same applies to FIGS. 5 and 6 described later.
(Effect of relief part)
In the above method, when the pasting portion 10t of the exterior body 10 is formed, the tabs are not cut as in the conventional case, and the tabs 21a and 21b and the relief portions 11a and 11b are reliably separated. Sealed. The reason will be described below.
[0021]
The width of the central portion in the groove region 501 of the mold 500 is slightly larger than the width of the tabs 21a and 21b, and the width of the welding resins 30a and 30b used for welding is the middle portion of the groove region 501 as described above. Since it is slightly wider than the width, in the formed escape portions 11a and 11b, the melted welding resins 30a and 30b are filled between the narrow portions 110a and 110b and the tabs 21a and 21b. Therefore, the clearance between the relief portions 11a and 11b and the tabs 21a and 21b is reliably sealed.
[0022]
Further, since the relief portion 11a (11b) has a shape having both a narrow portion and a wide portion as shown in FIG. 7 (a), the molten welding resin 30a (30b) is formed in the groove region of the mold and the tab 21a. A narrow gap with (21b) is not continuously formed along the extending direction of the tab. That is, the flowing direction of the welding resin 30a (30b) in the wide portion is dispersed not only in the extending direction of the tab 21a (21b) but also in the width direction. Therefore, it is difficult to apply a large tensile force in the extending direction of the tab 21a (21b), and thus the tab 21a (21b) is hardly cut.
[0023]
On the other hand, as shown in FIG. 7B, when the relief portion 61a (61b) has a simple rectangular shape and its width is as narrow as the narrow portion 110a (110b), the pasted portion When forming the mold, a narrow gap between the groove region of the mold and the tab 71a (71b) is continuously formed along the extending direction of the tab 71a (71b), and the molten welding resin 80a (80b) is melted. However, since the tab 71a (71b) is subjected to a large tensile force, the tab 71a (71b) is likely to be cut. In particular, the positive electrode tab 71a is easily cut because it is formed of an Al thin plate.
[0024]
On the other hand, if the shape of the relief portion is a simple rectangular shape and the width is as wide as the wide portions 111a and 111b, the gap through which the melted welding resins 80a and 80b circulate becomes wide. The cutting of is relaxed. However, in such a case, a through hole is likely to be generated in the escape portion, and the pasted portion cannot be reliably sealed.
[0025]
Further, in the relief portions 11a and 11b of the present embodiment, the narrow portions 110a and 110b are formed in the central portion of the pasting portion 10t, so that the welding resins 30a and 30b melted by heating when forming the pasting portion are provided. It is distributed in the inner and outer directions. Therefore, the pulling force applied to the tabs 21a and 21b is further reduced.
[0026]
Furthermore, since the overall shape of the relief portions 11a and 11b is a drum shape, the flow of the welding resins 30a and 30b flows while gradually spreading in the width direction of the tabs 21a and 21b. Accordingly, the tensile force applied to the tabs 21a and 21b is greatly reduced. (Modification)
In the above embodiment, the shape of the relief portions 11a and 11b is the drum shape shown in FIG. 4, so that the tab welding resins 30a and 30b melted by heating when forming the pasted portion are in the inner direction. Although the effect is enhanced by flowing in the outer direction and the flow being distributed in the width direction of the tabs 21a and 21b, the shape of the relief portions 11a and 11b is limited to this. Instead, any shape that has both a narrow portion and a wide portion is effective. In addition, in the above embodiment, an aluminum laminate sheet (a sheet in which an aluminum foil is covered with a PP layer or a PE layer) is used as a sheet material used for the exterior body, but the present invention is not limited to this.
[0027]
For example, the relief portions 11a and 11b may have a key shape in which narrow portions 110a and 110b protrude from only the central portion of the pasting portion 10t as shown in FIG. As shown, narrow portions 110a and 110b may be formed in the vicinity of the inner edge of the pasting portion 10t, and may have an inverted trapezoidal shape as a whole.
Moreover, the dimensions of the relief portions 11a and 11b shown in FIGS. 4 to 6 show an example, and it is necessary to change the dimensions according to the relative relationship with the tab and the welding resin.
[0028]
Further, in the battery 1 described above, both the relief portions 11a and 11b have the cross-sectional shape of the present invention. However, since aluminum (Al) is used for the tab, only the positive electrode side on which the tab is likely to be cut occurs. It may be applied.
About the escape part of description above, the effect was verified by the following examples and comparative examples.
[0029]
【Example】
Under the conditions shown below, the sealing test of (Example 1) to (Example 3) and (Comparative Example 1) to (Comparative Example 2) is performed, and the number of tab breaks and the number of leaks generated at that time are determined. Count and compare.
(conditions)
Number of tests: 200 cell seal pressure: 30 kPa
Mold temperature: 200 ℃
Positive side tab material: Aluminum (Al)
Positive electrode side tab dimension: width 3 mm x thickness 0.1 mm
Negative side tab material: Nickel (Ni)
Negative electrode side tab dimensions: width 3 mm x thickness 0.1 mm
Welding resin material: Modified polypropylene sealing resin Dimensions: 8 mm ^w x 0.06 mm ^t
(Example 1)
As shown in FIG. 4, the shape of the relief portion in the pasting portion of this embodiment is a drum shape in which the inner width of the narrow portions 110a and 110b is 5.5 mm.
(Example 2)
As shown in FIG. 5, the shape of the relief portion in the pasting portion of this embodiment is a key shape in which the narrow portions 111a and 111b have an inner width of 5.5 mm and a height of 1 mm.
(Example 3)
As shown in FIG. 6, the shape of the relief portion in the pasting portion of this embodiment is such that the narrow portions 112a and 112b are on the inner edge of the pasting portion on the power generating element side, and the inner width is 5.5 mm. Shape.
(Comparative Example 1)
As shown in FIG. 9 (a), the shape of the relief portion in this pasting portion is a 5.5 mm rectangle whose inner width is narrower than that of the welding resin. This has been generally used in the past.
(Comparative Example 2)
As shown in FIG. 9B, the shape of the relief portion in the pasted portion is a 10 mm rectangular shape whose inner width is wider than that of the welding resin.
(Evaluation results)
For the sealed batteries as in Examples 1 to 3 and Comparative Examples 1 and 2, the number of tab breaks was counted, and after leaving in an environment with a temperature of 80 ° C. and a humidity of 90% for 20 days, the battery was removed (n = 10) and the number of leaks was counted. The results are shown in Table 1.
[0030]
[Table 1]

[0031]
As shown in Table 1, in Examples 1 to 3, the number of tab breaks is smaller than that in Comparative Example 1. In particular, in Examples 1 and 2, tab breakage did not occur.
Next, regarding the number of leaks, leaks were confirmed in 9 cells out of 10 cells extracted in Comparative Example 2, but not in Examples 1 to 3. This is because, in Comparative Example 1, the flow of the welding resin is unidirectional when forming the affixed portion, and the tab is cut, and in Comparative Example 2, an unwelded portion is generated, so that the liquid leakage occurs. In contrast, in Examples 1 to 3, there is no unwelded portion in the escape portion of the pasted portion, and the flow of the welding resin when the pasted portion is formed is dispersed. Conceivable.
[0032]
Of these, those in which the narrow part of the relief part is in the middle between the outer edge part and the inner edge part of the pasting part as in Examples 1 and 2 are particularly effective.
[0033]
【The invention's effect】
As described above, in the sealed battery including the film-shaped exterior body of the present invention, the escape portion in the outer peripheral portion of the exterior body is formed into a shape having both a narrow portion and a wide portion, thereby ensuring sealing performance in the escape portion. At the same time, it is possible to suppress the occurrence of cutting of the tab when forming the pasting portion of the outer package.
[0034]
Further, in the method for producing a sealed battery having the film-like exterior body according to the present invention, in the sealing step, a wide portion and a narrow width with respect to the width direction of the tab in a state where the strip plate-like welding resin is superimposed on each tab. By using a mold in which a groove having a shape having a portion is formed and pressurizing while heating the outer peripheral portion of the exterior body, at least one of the relief portions in the outer peripheral portion is formed. It is possible to secure the sealing property and suppress the cutting of the tab.
[0035]
Therefore, the present invention is effective for improving the yield and for improving the reliability of the battery in the production of the sealed battery including the film-shaped outer package.
[Brief description of the drawings]
FIG. 1 is a perspective view (partially cross-sectional view) of a laminated battery according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
FIG. 3 is a schematic view showing a sealing step in the manufacture of a laminated battery according to an embodiment of the present invention.
4 is a cross-sectional view taken along the line B-B in FIG. 1;
FIG. 5 is a view showing a shape of a relief portion as a modified example.
FIG. 6 is a diagram showing a shape of a relief portion as a modified example.
FIG. 7 is a diagram conceptually showing a flow of a welding resin when forming a pasted portion.
FIG. 8 is a perspective (partly cross-sectional) view of a conventional laminated battery.
FIG. 9 is a diagram showing the shape of a conventional relief part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laminate type battery 10 Exterior body 11a, 11b Escape part 21a, 21b Tab 30a, 30b Welding resin 500 Mold 501 Mold groove area

Claims (5)

An electrode body in which a positive electrode plate and a negative electrode plate are arranged to face each other is sealed inside an exterior body made of a sheet material, and a tab is extended from each of the positive electrode plate and the negative electrode plate across the outer periphery of the exterior body. A film having a structure in which a relief portion for escaping the inner edge of the outer package in the thickness direction and width direction of the tab is formed in a region where the tab in the outer peripheral portion crosses, and the relief portion is filled with a sealing resin and sealed. A sealed battery provided with an outer casing,
At least one of the relief parts has a shape having both a wide part and a narrow part with respect to the width direction of the tab. The sealed battery according to claim 1, wherein the narrow portion is provided at a central portion in a tab extending direction of the escape portion. The sealed battery according to claim 1 or 2, wherein the escape portion has a drum shape. An electrode body manufacturing step of manufacturing an electrode body in which a positive electrode plate and a negative electrode plate are arranged to face each other and a tab is provided on each of the positive electrode plate and the negative electrode plate;
A sealing step of wrapping the electrode body such that the tab extends across the outer periphery of the outer package made of a sheet material, and welding the outer periphery to seal the electrode body inside the outer package. Prepared,
In the sealing step, an escape portion for escaping the inner edge of the exterior body in the thickness direction and the width direction of the tab is formed in a region where the tab crosses in the outer peripheral portion of the exterior body, and the escape resin is filled with a welding resin. It is a manufacturing method of a sealed battery provided with a film-like exterior body to be sealed,
In the sealing step, with the use of a mold in which a groove having a shape having both a wide portion and a narrow portion in the width direction of the tab is formed in a state in which a belt-like welding resin is superimposed on each tab, The method for producing a sealed battery having a film-like outer package according to claim 4, wherein at least one of the relief portions in the outer peripheral portion is formed by applying pressure while heating the outer peripheral portion of the body. The method for producing a sealed battery having a film-shaped outer package according to claim 4, wherein the band plate-shaped welding resin is wider than a narrow portion in a formed escape portion.

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