JP4443178B2 - Laminate battery manufacturing method and laminate battery manufacturing mold - Google Patents

Description

The present invention relates to a manufacturing method and a laminate cell manufacturing mold for the laminate batteries, especially without changing the conventional width of the mold, also to reduce the width of the sealing portion of the laminate battery same as the conventional laminate battery the degree of manufacturing methods and laminates cell manufacturing mold for the thickness of the tip is small laminated batteries which has a sealing reliability.

  With the rapid spread of portable electronic devices, the required specifications for the batteries used for them are becoming stricter year by year, especially those that are smaller and thinner, have high capacity, excellent cycle characteristics, and stable performance. ing. In the field of secondary batteries, lithium non-aqueous electrolyte secondary batteries, which have a higher energy density than other batteries, are attracting attention, and the proportion of lithium non-aqueous electrolyte secondary batteries shows a significant increase in the secondary battery market. ing.

  The lithium non-aqueous electrolyte secondary battery includes a negative electrode in which a negative electrode mixture containing a negative electrode active material that occludes and releases lithium ions is applied to both surfaces of a negative electrode core (current collector) made of an elongated sheet-like copper foil, and the like. A separator made of a microporous polypropylene film, etc., is placed between the positive electrode core, which contains a positive electrode active material that absorbs and releases lithium ions, on both sides of a positive electrode core made of an elongated sheet-like aluminum foil. Then, after the negative electrode and the positive electrode are wound in a columnar shape or an elliptical shape while being insulated from each other by a separator, in the case of a rectangular battery, the wound electrode body is further crushed to form a flat wound electrode body. It is manufactured by connecting a negative electrode tab and a positive electrode tab to each predetermined part of the positive electrode and covering the outside with an exterior.

  As this exterior, metal exterior cans are mainly used to give strength, but in recent years, laminate batteries using laminate films have been manufactured for the purpose of reducing weight and increasing battery capacity per unit volume. It has come to be. (See Patent Document 1)

  Hereinafter, the manufacturing process of the laminated battery 50 conventionally performed conventionally is demonstrated using FIG. First, the flat wound electrode body 11 is manufactured in the same manner as the above-described conventional example. At this time, the flat wound electrode body 11 has the negative electrode tab 12 welded to the negative metal core foil exposed portion and the positive electrode tab 13 welded to the positive metal core foil exposed portion. deep.

  Subsequently, as shown in FIG. 6A, a known laminate film 14 having a predetermined size, for example, an aluminum laminate film having a three-layer structure of polyethylene terephthalate, an aluminum film and unstretched polypropylene (see Patent Document 1 below). Paragraph [0004]) is folded in half, so-called cup-shaped, and the flat wound electrode body 11 is disposed therein, and thin sealing material 15 on both sides of the lead-out portions of the negative electrode tab 12 and the positive electrode tab 13 as necessary. , 15 ′ are disposed, and the top portion (tab side) of the laminate film 14 is welded by controlling it in a stereotaxic manner using a bar-shaped mold (not shown) to form the top sealing portion 16. . At this time, an unwelded portion 16 ′ is provided at the outer edge of the top sealing portion 16 in order to prevent the sealant layer melted from the laminate film 14 from protruding and adhering to the mold.

  Next, as shown in FIG. 6B, the first side sealing portion 17 is formed by welding one side portion side of the laminate film 14 using a bar-shaped mold 19. Also in this case, the outer edge of the first side sealing portion 17 is provided with an unwelded portion 17 ′ so that the sealant layer melted from the laminate film does not protrude and adhere to the mold. Next, a liquid electrolyte is injected from the other side portion side 18. Then, the liquid electrolyte sufficiently penetrates into the flat wound electrode body 11. Thereafter, as shown in FIG. 6C, the other side of the laminate film 14 is temporarily welded with a bar-shaped mold 19 to form a temporary sealing portion 20. Next, after precharging and aging, as shown in FIG. 6 (d), the other side of the laminate film 14 is welded by controlling it in a stereotaxic manner with a bar-shaped mold 19. 21 is formed. And the unnecessary part of the said laminate film is cut | disconnected, and the conventional laminated battery 50 as shown in FIG.6 (e) is obtained.

JP 2002-42881 A (paragraphs [0002] to [0013])

  In such a conventional laminated battery manufacturing method, a bar-shaped mold is used to seal the top sealing portion 16, the first side sealing portion 17, and the second side sealing portion 21 with three locations. 7 is a partial cross-sectional view taken along the line XX ′ of FIG. 6 (e) when the top sealing portion 16 (tab side portion) of the battery is heat sealed. As described above, the sealant and the tab protection resin of the laminate film 14 protruded when the films were welded, and the resin 22 was accumulated, and the thickness of the tip portion was increased. Such a laminated battery 50 is provided with a printed wiring board 23 in which a protective element or the like is disposed on the surface of the top sealing portion for battery safety measures. If it is thick, it is difficult to dispose the printed wiring board 23 on which a protective element or the like is disposed, and there is a problem that the battery is difficult to fit in the package.

  Further, in order to suppress the amount of the protruding resin 22 to a small amount, when welding is performed using a mold having a width larger than the top sealing portion 16 of the battery, the tabs 12 and 13 and the aluminum layer exposed on the end face of the laminate film There is a short circuit or a problem that the resin 22 adheres to the heater head, resulting in a decrease in process yield or poor welding.

  In addition, after welding, once the portion where the resin 22 has accumulated is hot-pressed to reduce the thickness of the top sealing portion, problems such as shorts, tab breaks, an increase in the number of processes and tact-down will occur. It was.

  In manufacturing such a laminated battery, the present inventors have obtained the same sealing reliability as that of a conventional laminated battery even if the top sealing part thickness is reduced without changing the width of the conventional mold. As a result of various studies to obtain a laminated battery, the above-described conventional mold is provided by providing a step in the top seal mold and making the width of the top seal mold smaller than the width of the top sealing portion. As a result, it was found that all the problems in the case of using can be solved, and the present invention has been completed.

That is, the invention of the method for manufacturing a laminated battery according to claim 1 of the present application is characterized by having at least the following steps (1) to (2).
(1) A step of inserting an electrode assembly having a positive electrode tab and a negative electrode tab into a laminate film having a bottom folded in two,
(2) The top portion of the laminate film from which the positive electrode tab and the negative electrode tab are led out is a pair of bar-shaped molds, and the portion of the mold corresponding to the tip side of the top portion A step portion having a constant width is formed at a side end portion along the length direction of the sealing portion, and the height to the surface of the step portion with respect to the base portion of the mold is the sealing portion of the mold. Welding using a mold that is lower than the height to the surface of the mold , and the total width of the stepped portion of the mold and the width of the sealing portion is smaller than the width of the top portion of the laminate film Process.

The invention according to claim 2 of the present application is the method for producing a laminated battery according to claim 1, wherein, in the step (2), as the mold, the positive electrode tab and the negative electrode tab are derived. What used the thing in which the groove part of this was formed was used.
The invention according to claim 3 of the present application is the method for manufacturing a laminated battery according to claim 1 or 2 , wherein in the step (2), as the mold , the bar-shaped mold is used. An L-shaped mold in which a side sealing portion is formed, and the laminate film uses an L-shaped mold in which the height of the side sealing portion is the same as that of the sealing portion of the mold. The top part and the one side part are welded at the same time.

Furthermore, the invention according to claim 4 of the present application is a mold for manufacturing a laminated battery used for carrying out the method for manufacturing a laminated battery according to claim 1, and comprises a pair of bar-shaped molds. A step portion having a constant width is formed at a side end portion along the length direction of the sealing portion of the bar-shaped mold, and the height to the surface of the step portion with respect to the base portion of the mold Is lower than the height to the surface of the sealing portion of the mold .

Further, the invention according to claim 5 of the present application is characterized in that the laminated battery manufacturing mold according to claim 4 further includes a groove for leading out the positive electrode tab and the negative electrode tab.

The invention according to claim 6 of the present application is the mold for manufacturing a laminated battery according to claim 4 or 5 , further comprising a side part sealing having the same height as the sealing part of the bar-shaped mold. It is characterized by being combined with a bar-shaped metal mold for making an L-shaped metal mold.

According to the method for manufacturing a laminated battery according to claim 1 of the present application, the thickness of the entire top sealing portion can be controlled to be small, and the same sealing reliability as that of the conventional one can be achieved. A laminate battery capable of being manufactured can be easily and accurately manufactured.

According to the method for manufacturing a laminated battery according to claim 2 of the present application, all the top sealing portions are sealed to have a predetermined thickness in consideration of the thicknesses of the positive electrode tab and the negative electrode tab. be able to. Further, according to the method for manufacturing a laminated battery according to claim 3 of the present application, the top part and one side part can be sealed simultaneously, so the number of steps can be reduced and the manufacturing efficiency of the laminated battery is improved. To do.

Furthermore, according to the manufacturing mold for the laminate battery according to claim 4 and 5 of the present application, it will be able to implement the method of manufacturing a laminate battery of easily claim 1, wherein, in addition, the mold Since the entire width of the sealing portion including the step portion is smaller than the width of the top sealing portion , the molten resin is less exposed from the laminate film, so that the molten resin does not adhere to the heater head, The process yield is improved and poor welding is less likely to occur.

Further, according to the laminate battery manufacturing mold according to claim 6 of the present application, the top portion and the one side portion can be welded simultaneously, so the number of steps can be reduced and the manufacturing efficiency of the laminate battery is improved. .

It will be described below in more detail by the best mode for carrying out the present invention examples and comparative examples, examples manufacturing method and a laminate of the laminate batteries for embodying the technical idea of the present invention shown below It is intended to illustrate battery manufacturing molds and is not intended to limit the invention to these.

In addition, the difference between the Example of this invention and a comparative example is only the structure of the top sealing part based on the difference in the metal mold | die used, Comprising: The manufacturing process of the laminated battery of an Example and a comparative example was already mentioned above. Since it is substantially the same as the manufacturing process of the conventional laminated battery using a bar-shaped mold, it will be described with reference to FIG. 6 as necessary.

<Manufacture of laminated batteries>
First, the manufacturing process of the laminated battery common to an Example and a comparative example is demonstrated. First, as a positive electrode active material, a mixture of a certain amount of spinel type lithium manganate typified by LiMn ₂ O ₄ and lithium cobaltate typified by LiCoO ₂ is used. Was mixed with a fluororesin binder at a certain ratio to form a positive electrode mixture, applied to both surfaces of the aluminum foil, dried and rolled to obtain an electrode plate. In addition, what added the different element to lithium manganate or cobalt oxide can also be used as a positive electrode active material from which the same effect is acquired.

  Further, the negative electrode was prepared by mixing a carbon material and a fluororesin binder at a certain ratio, coating the both surfaces of the copper foil, drying and rolling to form an electrode plate.

  The positive electrode plate and the negative electrode plate thus manufactured are wound in a spiral shape in a state of being insulated from each other through two separators made of a porous polyethylene film, and are crushed to produce a flat wound electrode body 11. did. At this time, the flat wound electrode body 11 is formed by welding the negative electrode tab 12 provided with the sealing material 15 made of polypropylene (PP) resin to the negative electrode copper foil exposed portion and the positive electrode aluminum foil exposed portion. Further, the positive electrode tab 13 provided with the sealing material 15 ′ made of PP resin was welded.

  The formed flat wound electrode body 11 is housed in a so-called cup-molded laminate exterior in which the flat wound electrode body 11 is folded in two with a known laminate film (for example, aluminum laminate film) 14 having a predetermined size. did. The total thickness of this laminate film is about 0.100 mm, and the thickness of the sealant layer is about 0.030 mm.

  Next, the top sealing portion 16 is formed by welding the top portion (tab side) of the laminate film 14 by a localization method using the mold of the example or the comparative example (see FIG. 6A). Next, in the same manner as in the conventional example shown in FIGS. 6 (b) to 6 (e), one bar of the laminate film 14 is used by using a common bar-shaped mold 19 in both the example and the comparative example. After the side portion side is welded to form the first side sealing portion 17, the liquid electrolyte is injected from the other side portion side 18 (see FIG. 6B), and the other side of the laminate film 14 is placed on the bar. After temporarily welding with a metal mold to form a temporary sealing portion 20 (see FIG. 6 (c)), precharging and aging, the other side of the laminate film 14 is positioned with a bar-shaped metal mold 19 The second side sealing portion 21 was formed by controlling and welding (see FIG. 6D). Finally, unnecessary portions of the laminate film were cut to obtain laminate batteries of Examples and Comparative Examples. (See FIG. 6 (e)). The standard of the obtained battery has a design capacity of 640 mAh, and all the examples and comparative examples have the same configuration except for the configuration of the welded portion of the top portion (tab side).

又は、ポリプロピレングリコールジメタクリレート

を重量比で１２：１で混合した溶液に重合開始剤としてｔ−ヘキシルパーオキシピバレートを５０００ｐｐｍ添加したものを、先の電池巻取り体を収納したアルミ外装体内に注液したあと、６０℃オーブン中に３時間静置し、硬化させたものを使用した。 As the polymer electrolyte, an electrolytic solution obtained by dissolving lithium hexafluorophosphate (LiPF ₆ ) in a non-aqueous solvent (organic solvent) at a rate of 1 mol / l and polypropylene glycol diacrylate

Or polypropylene glycol dimethacrylate

After adding 5000 ppm of t-hexylperoxypivalate as a polymerization initiator to a solution prepared by mixing 12 wt. A cured product was allowed to stand in an oven for 3 hours.

  Nonaqueous solvents (organic solvents) include carbonates, lactones, ethers, esters, aromatic hydrocarbons, etc. Among these, carbonates, lactones, ethers, ketones, esters And the like, and carbonates are more preferably used. Two or more of these solvents can be mixed and used.

  Specific examples of carbonates include propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, γ-dimethoxyethane, tetrahydrofuran, anisole, 1,4-dioxane, diethyl carbonate, and the like. Two or more of these carbonates may be mixed and used.

The electrolyte constituting the nonaqueous electrolytic solution, in addition hexafluoride lithium phosphate (LiPF _6), lithium perchlorate (LiClO _4), lithium borofluoride (LiBF _4), hexafluoro arsenate lithium (LiAsF ₆₎ , Lithium trifluoromethylsulfonate (LiCF ₃ SO ₃ ), bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₂ ) ₂ ], bispentafluoroethylsulfonylimide lithium LiN (SO ₂ C ₂ F ₅ ) ₂ and these A mixture of these can be selected and used as appropriate.

In both the examples and comparative examples, the width of the top sealing portion of the laminated battery was 4 mm, and the mold width a was 2.50 mm. Further, both the mold of Examples and Comparative Examples, in order to prevent short-circuit between the Al tabs and laminate casing, is provided with a relief tab, the height e of the tab relief was 0.060 mm. Further, as the thin sealing materials 15 and 15 'provided in the tab portion, both positive and negative electrode tabs having a film thickness of 0.070 mm / sheet were used.

<Comparative example>
FIG. 1 shows the mold of the comparative example, and FIG. 2 shows a state in which the battery top portion is welded using two of the molds of this comparative example as a set (note that the lower mold is not shown). . 1A is a front view of a comparative mold, FIG. 1B is a bottom view, and FIG. 1C is taken along line AA ′ of FIG. 1A. It is a partially expanded sectional view along.

The mold 25 of this comparative example has a sealing part 26 and a tab relief part 27, the total welded part width a of the mold is the same as the sealing part width b of the sealing part 26, and a = b = 2.50 mm. Further, the height e of the tab relief 27 formed in the groove shape is e = 0.060 mm. Table 1 shows the dimensions of each part of the mold of this comparative example.

  Using the mold 25 of this comparative example, the thickness of the sealing portion between the tabs becomes an average of 0.180 mm (0.160 mm to 0.200 mm), and the width of the unwelded portion of the top sealing portion is 0.60 mm ± When the battery top portion is welded by controlling the localization so as to be 0.30 mm, as shown in FIG. 2 which is a partial cross-sectional view corresponding to the YY ′ portion of FIG. The sealant and the tab protection resin protruded, the resin 22 accumulated, and the thickness of the tip portion increased.

  Thus, while measuring the average value of the welding width of the top part of the laminated battery 50 manufactured using the metal mold | die of a comparative example, the sealing part thickness between tabs, and the front-end | tip part thickness, it is 80% in a 40% charge state, respectively. The battery swell dimensions (average value) and the unsealed state of the top sealing part after storage at 20 ° C. and 90% relative humidity for 20 days were measured, and the results are shown in Table 2. In addition, the relationship of the welding width of the top part of the laminated battery 50 of the obtained comparative example, the sealing part thickness between tabs, and the front-end | tip part thickness is as showing in FIG. Further, in the comparative example, when the mold 25 is removed, the thickness of the tip changes due to the elastic force of the laminate film 14, but for the tip thickness, a printed wiring board (see FIG. 7) on which a protective element or the like is disposed, A value measured in a load state of 100 g in consideration of pressing by the package is shown.

<Examples 1-3>
Next, the metal mold | die of Examples 1-3 is shown in FIG. 3, and the state which welded the battery top part using two metal mold | dies of this Example 1-3 in one set is shown in FIG. The illustration of the mold was omitted). In FIG. 3, FIG. 3 (a) is a front view of the molds of Examples 1 to 3, FIG. 3 (b) is a bottom view, and FIG. 3 (c) is BB in FIG. 3 (a). It is a partially expanded sectional view along line '.

The molds 28 of the first to third embodiments have a step part 31 along the length direction of the sealing part 29, the tab relief part 30 and the mold 28, and the step part 31 of the mold 28 and the sealing part 29 are sealed. The total welding width a (total welding width) including the stopper 29 is all equal to that of the comparative example, and a = 2.50 mm. Further, the width (sealing portion width) b of the sealing portion 29 of the mold 28 is such that b = 1.50 mm (Example 1), b = 1.75 mm (Example 2), and b = 2.00 mm (implementing). Example 3) and the width c of the stepped portion 31 is c = 1.00 mm (Example 1), c = 0.75 mm (Example 2), and c = 0.50 mm (Example 3). Changed. That is, in Examples 1 to 3, the width b of the sealing portion 29 of the mold 28 and the width c of the stepped portion 31 have a relationship of b + c = a, and this portion is a region to be welded. ing. Note that the height h1 to the surface of the stepped portion 31 with respect to the base portion 28a of the mold 28 is smaller than the height h2 to the surface of the sealing portion 29 by d. The height d of the step is referred to as Example 1-3 together all 0.20 mm, the tab relief height e is equal to that of all comparative examples, was e = 0.060 mm. The dimensions of each part of the molds of Examples 1 to 3 are collectively shown in Table 1.

  Further, using the mold 28 of Examples 1 to 3, the welded portion width A of the top portion of the laminated battery 10 manufactured by controlling the orientation so that the thickness of the sealed portion between the tabs is 0.180 mm on the average, sealing The average value of the part width B, the step part width C, the step part thickness D, the inter-tab sealing part thickness, and the tip part thickness was measured, and at 40% charge state, at 80 ° C. and 90% relative humidity. The battery swelling dimensions (average value) after storage for a day and the unsealed state of the top sealing part were measured, and the results are summarized in Table 2.

  In addition, the welding part width A, the sealing part width B, the step part width C, the step part thickness D, the inter-tab sealing part thickness, and the tip part thickness of the top part of the obtained laminated batteries 10 of Examples 1 to 3 The relationship is as shown in FIG. Further, in Examples 1 to 3, when the mold 28 is removed, the thickness of the tip changes due to the elastic force of the laminate film 14, but the tip thickness is the same as in the comparative example in which the protective element is disposed. The values measured in a load state of 100 g in consideration of pressing by the wiring board (see FIG. 7) and the package are shown.

As is clear from the results in Table 2 above, all of the laminated batteries 10 manufactured using the molds 28 of Examples 1 to 3 have the sealing part width B smaller than the welding part width A of the comparative example. However, the tip thickness is smaller than that of the comparative example, and even when stored at a high temperature and high humidity of 80 ° C. and a relative humidity of 90% for 20 days, the swelling of the battery is similar to that of the comparative example. In addition, none of the sealing portions were opened, and it was confirmed that the sealing reliability was comparable to that of the conventional example.

  In the first to third embodiments, the top sealing and the side sealing are individually performed using a bar-shaped mold. However, the top sealing and the side sealing are performed simultaneously using an L-shaped mold. Is also possible. The shape of the L-shaped mold in this case will be described with reference to FIG. 5, but the configuration of substantially the same parts as the molds of Examples 1 to 3 in FIG. Description is omitted. 5A is a front view of the L-shaped mold, FIG. 5B is a plan view, FIG. 5C is a left side view, and FIG. 5D is a bottom view.

An L-shaped mold 40 shown in FIG. 5 has a top sealing portion 41 and a side sealing forming portion 42, and the top sealing forming portion 41 is the top sealing of the first to third embodiments shown in FIG. The side seal forming part 42 has the same configuration as the bar-shaped mold 19 shown in FIG. 6B of the conventional example. The top sealing part mold has a structure integrated with the base sealing part 29 so that the height of the sealing part 29 of the top sealing part mold is the same as the height of the side sealing part 42. . If this L-shaped mold 40 is used, the top sealing and the side sealing of the laminate film can be performed by a single operation, leading to a reduction in man-hours.

FIG. 1A is a front view, FIG. 1B is a bottom view, and FIG. 1C is a part along line AA ′ in FIG. 1A. It is an expanded sectional view. It is a figure which shows the state which welded the battery top part using the metal mold | die of FIG. The metal mold | die of Examples 1-3 is shown, Fig.3 (a) is a front view, FIG.3 (b) is a bottom view, FIG.3 (c) follows the BB 'line | wire of Fig.3 (a). FIG. It is a figure which shows the state which welded the battery top part using the metal mold | die of FIG. It is a figure which shows the L-shaped metal mold | die of this invention, Fig.5 (a) is a front view of an L-shaped metal mold | die, FIG.5 (b) is a top view, FIG.5 (c) is a left view, FIG.5 (d). ) Is a bottom view. It is a figure explaining each manufacturing process of the laminated battery of a prior art example. It is a partial cross section figure which followed the XX 'line | wire of the laminated battery of FIG.6 (e).

DESCRIPTION OF SYMBOLS 10, 50 Laminated battery 11 Flat winding electrode body 12 Negative electrode tab 13 Positive electrode tab 14 Laminating film 16 Top sealing part 17, 21 Side sealing part 22 Resin 23 Printed wiring board 25, 28 Mold 26, 29 Sealing part 27 , 30 tab relief
28a Mold base 31 Step 40 L-shaped mold

Claims (6)

A method for producing a laminated battery, comprising at least the following steps (1) to (2):
(1) A step of inserting an electrode assembly having a positive electrode tab and a negative electrode tab into a laminate film having a bottom folded in two,
(2) The top portion of the laminate film from which the positive electrode tab and the negative electrode tab are led out is a pair of bar-shaped molds, and the portion of the mold corresponding to the tip side of the top portion A step portion having a constant width is formed at a side end portion along the length direction of the sealing portion, and the height to the surface of the step portion with respect to the base portion of the mold is the sealing portion of the mold. Welding using a mold that is lower than the height to the surface of the mold , and the total width of the stepped portion of the mold and the width of the sealing portion is smaller than the width of the top portion of the laminate film Process. 2. The production of a laminated battery according to claim 1, wherein, in the step (2), the mold further has a groove for leading out the positive electrode tab and the negative electrode tab. Method. In the step (2), as the mold , an L-shaped mold in which a side sealing portion is formed with respect to the bar-shaped mold, and the height of the side sealing portion is the mold. of using the same height as it is the L-shaped die and the sealing unit, according to claim 1 or 2, characterized in that none to simultaneously weld the top portion and the one side of the laminate film Manufacturing method for laminated battery. It consists of a pair of bar-shaped molds, and a step portion having a constant width is formed at the side end along the length direction of the sealing part of the bar-shaped mold, and the base of the mold is used as a reference 2. The laminate battery manufacturing method according to claim 1, wherein a height to the surface of the stepped portion is lower than a height to the surface of the sealing portion of the mold. 3. Mold for manufacturing laminated battery . Furthermore, it has a groove part for derivation | leading-out of a positive electrode tab and a negative electrode tab, The metal mold | die for laminated battery manufacture of Claim 4 characterized by the above-mentioned. Furthermore, in claim 4 or 5, characterized in that in combination with the bar-shaped mold for the side part sealing the same height as the sealing portion of the bar-shaped mold are made with L-shaped die A mold for manufacturing a laminated battery as described.

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