JP2014032924A - Film sheathed battery and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film sheathed battery which has a film member constituting a sheath material not easily peeled off and less possibility of causing dielectric resistance failures.SOLUTION: A film sheathed battery has a battery element 4, which comprises a positive electrode 5 and negative electrodes 6 stacked on each other with separators 7 therebetween, and is stored inside a bag-shaped sheath material 3 made of film members 2; and the sheath material 3 sealed therein. The sheath material 3 at least has a terminal side and a lateral side, each of the positive electrode 5 and the negative electrodes 6 is connected to an electrode terminal, and the electrode terminal is protruded outside through the terminal side from the inside of the sheath material 3. Within a portion where the film members 2 covering both sides of the battery element 4 are overlapped with each other, a blocking region 10b located at an inner side of a corner where the terminal side and the lateral side intersects has a width of less than 3 mm.

Description

  The present invention relates to a film-clad battery in which a battery element is enclosed inside a packaging material made of a film-like member, and a method for manufacturing the same.

  Lithium ion secondary batteries are used as main power source batteries for portable electronic devices, electric vehicles, hybrid vehicles, electric bicycles, cordless electric tools, and the like. In particular, a film-clad battery in which a battery element is enclosed in a packaging material made of a thin film member having a large capacity and excellent energy mass efficiency and volumetric efficiency is preferably used.

  In general, a film-like member constituting an exterior material is a metal foil such as an aluminum foil and polyethylene (PP) which is laminated on the inner surface of the metal foil and has corrosion resistance to an electrolytic solution and has good heat fusion properties. Laminated film consisting of an inner surface resin layer such as polypropylene (PE) and an outer surface resin layer such as polyimide (PI), polyethylene terephthalate (PET), and nylon (registered trademark) with high corrosion resistance laminated on the outer surface of the metal foil. It is.

  In such a film-clad battery, after a long laminate film is folded in two, the battery element is accommodated so as to be sandwiched between the folded laminate films, and the peripheral edge of the laminate film has three sides other than the folded portion. The laminate film is formed by thermally welding and sealing a portion where the laminate films overlap each other.

JP 2009-181898 A

  A film-clad battery having a rectangular planar shape is manufactured by performing heat welding on each side of the peripheral edge of the laminate film. In other words, terminal sides (sides where the electrode terminals pass among the peripheral sides of the film-like member) and side sides (sides other than the terminal sides among the peripheral sides of the film-like member, ie, sides where the electrode terminals do not pass) ) Are individually welded using a heater block. In this manufacturing method, the corner portion of the laminate film is heated twice by the terminal side heater block and the side side heater block, so that it is greatly affected by heat compared to other portions. Normally, when welding the terminal sides of the film-like member, it is necessary to perform the welding by heating to a higher temperature than the side sides in consideration of heat radiation from the electrode terminals. Since the corners of the laminate film are located away from the electrode terminals on the terminal side, not only is the terminal side welded exposed to a temperature higher than the melting point of the laminate film but also subjected to strong thermal damage, as well as for the terminal side Since it was also heated by the heater block, it was severely damaged by heat.

  In general, when a laminate film is heat-welded, blocking due to tilting heat or residual heat (welding with extremely low adhesive strength caused by resin pseudo-welding or foaming) occurs in an unwelded portion inside the peripheral edge. As shown in FIG. 2, when the cross section of the outer packaging material of the completed film-clad battery is viewed, the outermost peripheral edge portion 10a is pressed and heated by the heater block, so that the overlapping laminate films adhere to each other as a whole. And flatness is high. However, in the portion 10b on the inner side in plan view, the flatness is low, and pseudo welding or foaming partially welded due to heat conduction from the peripheral edge portion occurs, and blocking occurs. In the region 10b where the blocking occurs, the welded surface easily peels off with a small stress, and at that time, a crack occurs in the inner surface resin layer of the laminate film, leading to the occurrence of insulation resistance failure.

  Therefore, as described above, there has been a problem that the corners of the laminate film are more likely to be blocked due to severe thermal damage than the other portions, and are likely to cause defective insulation resistance.

  In the configuration described in Patent Document 1, a part (spacer) for enhancing insulation is added to a portion where the electrode terminal is located where a short circuit is a concern. However, in this configuration, parts that are not related to the original function of the battery are added, resulting in increased costs and an obstacle to market competition.

  Accordingly, an object of the present invention is to provide a film-clad battery that solves the above-described problems and that is unlikely to peel off the film-like member that constitutes the exterior material and that is less likely to cause an insulation resistance failure, and a method for manufacturing the same. .

  In order to solve the above-described problems, a film-clad battery according to the present invention includes a battery element having a configuration in which a positive electrode and a negative electrode are stacked via a separator, and is housed in an exterior material composed of a film-like member. Is a film-clad battery in which the packaging material has at least one terminal side and side sides, electrode terminals are connected to the positive electrode and the negative electrode, respectively, and the electrode terminals are terminals from the inside of the packaging material. The width of the blocking region located inside the corner where the terminal side and the side side intersect among the overlapping parts of the film-like member that passes through the side and protrudes to the outside and covers both sides of the battery element. Is less than 3 mm.

  According to the present invention, the blocking region between the heat-welded portion and the unwelded portion of the film-like member is small, the film-like member is difficult to peel off, and the occurrence of poor insulation is suppressed. Thereby, it is possible to maintain high performance as a battery and improve reliability without increasing the number of parts.

(A) is a top view of an example of the film-clad battery of this invention, (b) is the front view, (c) is the side view. It is an expanded sectional view which shows the heat welding state of the film-like member of a film-clad battery. (A) is a top view of the 1st heater block used for the manufacturing method of the film-clad battery of Example 1 of this invention, (b) is a top view of a 2nd heater block. (A) is a top view which shows the heating state by the 1st heater block shown to Fig.3 (a), (b) is a top view which shows the heating state by the 2nd heater block shown in FIG.3 (b). It is a graph which shows the evaluation result of the film-clad battery by a peeling test. (A) is a top view of the 1st heater block used for the manufacturing method of the film-clad battery of Example 2 of this invention, (b) is a top view of a 2nd heater block. (A) is a top view which shows the heating state by the 1st heater block shown to Fig.6 (a), (b) is a top view which shows the heating state by the 2nd heater block shown in FIG.6 (b). It is a top view of the 1st heater block used in the modification of a comparative example. It is a top view of the 1st heater block used for the manufacturing method of the film-clad battery of Example 2 of this invention. (A) is a top view which shows the heating state by the 1st heater block shown in FIG. 9, (b) is a top view which shows the heating state by a 2nd heater block. (A) is a top view of the 1st heater block used for the manufacturing method of the film-clad battery of Example 3 of this invention, (b) is a top view of a 2nd heater block. (A) is a top view which shows the heating state by the 1st heater block shown to Fig.11 (a), (b) is a top view which shows the heating state by the 2nd heater block shown in FIG.11 (b). (A) is a top view which shows concretely the heat welding state of the film-like member of the film-clad battery of a comparative example, (b) is the schematic which shows it typically.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a film-clad battery. The film-clad battery 1 includes a bag-shaped exterior material 3 formed by bending a long laminate film 2 and a battery element 4 accommodated inside the exterior material 3. The battery element 4 has a configuration in which a positive electrode 5 and a negative electrode 6 are laminated with a separator 7 interposed therebetween. The positive electrode 5, the negative electrode 6, and the separator 7 may be present in a single layer, or the multiple positive electrodes 5 and the negative electrodes 6 may be alternately stacked with the separators 7 interposed therebetween. Good. The electrode terminals (the positive terminal 5a and the negative terminal 6a) connected to the positive electrode 5 and the negative electrode 6, respectively, protrude to the outside through one side (terminal side 3a) of the packaging material 3. An electrolytic solution 14 (see FIG. 2) is sealed inside the outer package 3, and the battery element 4 is immersed in the electrolytic solution 14.

  In the film-clad battery 1 having such a configuration, as shown in FIG. 2, the laminate film 2 constituting the packaging material 3 includes a metal foil 2a such as an aluminum foil, an inner surface resin layer 2b such as PP or PE, and PI. And a film-like member made of an outer surface resin layer 2c such as PET or nylon (registered trademark). And the bag-shaped exterior material 3 is comprised by joining the peripheral parts other than the bending part 3c of the laminate film 2 in the state which the folded laminated film 2 pinched | interposed the battery element 4 in between. The positive electrode terminal 5 a and the negative electrode terminal 6 a of the battery element 4 pass through one side of the laminate film 2 and extend to the outside of the exterior material 3. That is, the exterior material 3 (laminate film 2) has a side (herein referred to as “terminal side 3a”) through which the positive electrode terminal 5a and the negative electrode terminal 6a pass, and a side (terminal) through which the positive electrode terminal 5a and the negative electrode terminal 6a do not pass. There is a side other than the side 3a, which is referred to as “side side 3b” in this specification. In general, one of the short sides of the exterior material 3 having a rectangular planar shape is the bent portion 3c, the other short side is the terminal side 3a, and the two long sides are both side sides 3b. .

  The film-clad battery 1 of the present invention is manufactured by being individually heat-sealed using a heater block for the terminal side 3a and a heater block 3b for the side. The temperature of the heater block set at this time is appropriately selected so that sufficient welding occurs in consideration of the melting point of the inner surface resin layer 2b of the laminate film. In general, the heater block for the terminal side is set at a temperature higher than that of the heater block for the side side in consideration of heat radiation from the electrode terminal during welding.

  Next, the confirmation method of the heat welding part 10a, the blocking area | region 10b, and the non-welding part 10c which are made after welding of the terminal side 3a and the side 3b is demonstrated.

(First evaluation method)
The completed film-clad battery 1 is cut into an appropriate size, and the outer surface resin layer (eg, nylon layer) 2c and metal foil (eg, aluminum foil) 2a of the laminate film 2 are etched with an acid. When the two inner resin layers (for example, PP layer) 2b exposed thereby are stained and visually observed through a microscope or directly through a microscope, there are portions where the color tone changes. And contrast. That is, as shown in FIGS. 2 and 13, on the outer side of the portion of the exterior member 3 that houses the battery element 4, a portion 10 a having high flatness, which is a peripheral portion located on the outermost side, and on the inside in a plan view A distinction is made between three parts, a part 10b having low flatness and a part 10c having a different inner color tone. The portion with high flatness located at the outermost peripheral portion is a heat welded portion 10a that is heated in direct contact with the heater blocks 8 and 9, and the laminate films 2 are firmly heat-welded with no gap therebetween. And the innermost different part of the color tone is the unwelded portion 10c where the laminate films 2 are not in contact with each other and are not welded because the battery element 4 is interposed. And the part which is located between the heat welding part 10a and the unwelded part 10c, has low flatness, and differs in color tone from the unwelded part 10c is the blocking area | region 10b. The blocking region 10b is a portion where the laminated films 2 are welded in pieces due to heat or residual heat although they are not in direct contact with the heater blocks 8 and 9.

  Usually, since the heater block has a fixed width along the terminal side or side, the boundary line between the heat-welded portion 10a and the blocking portion 10b is visually observed or displaced at least at one or more locations regarding the flatness of the laminate film. It can be determined by observing with a meter. The boundary line between the heat-welded part 10a or the blocking part 10b and the unwelded part 10c can be determined by the already-described contrast. The width of the blocking region 10b on the terminal side or side is maximized when the blocking region 10b sandwiched between the two types of boundary lines is maximized in the direction perpendicular to the terminal side or side in the laminate film surface. To do. In addition, the blocking width of the corner portion is a direction that forms 45 degrees with respect to the terminal side from the intersection of the boundary line between the thermal welding portion and the blocking region on the terminal side and the boundary line between the thermal welding portion and the blocking region on the side side. Then, the width of the blocking region can be examined and obtained by dividing the value by √2.

(Second evaluation method)
Instead of the first visual evaluation method described above, the heat welded portion 10a, the blocking region 10b, and the unwelded portion 10c can be evaluated by a second evaluation method based on a peel test. In the 2nd evaluation method, what was notched toward the laminated body side from the welding part by the width | variety of the exterior material 3 of the completed film exterior battery 1 is prepared. The laminate film 2 is peeled off from the cut-out portion toward the peripheral portion, and the peel strength at that time (the force required to peel off the laminate films 2) is measured according to Japanese Industrial Standard JISZ0238. According to the second evaluation method, as shown in FIG. 5, since the battery element 4 is interposed in the central portion of the outer package 3, the laminate films 2 are not welded to each other, and a force for peeling off is required. No (peel strength is almost zero). When the laminate film 2 is peeled off from the central portion, a force for peeling off from a certain portion is required, and the peel strength gradually increases as the outer peripheral portion 3 is approached. The peel strength suddenly increases and becomes constant at a certain point. In this peel test, the region where the peel strength is almost zero is the unwelded portion 10c, and the region where the peel strength is high and is almost constant is the heat welded portion 10a. Then, the peel strength gradually increases from the portion where the heat-welded portion 10a and the unwelded portion 10c, that is, the peel strength is not zero and the peeling force is required, and the peel strength increases rapidly and A region up to a constant part corresponds to the average width of the blocking region 10b. Even when the second evaluation method based on the peel test is performed, the same result as that of the first visual evaluation method can be obtained.

  Furthermore, the insulation defect inspection method for film-clad batteries will be described.

  The insulation failure test is performed between the exposed aluminum foil portion on the cut surface of the laminate film 2 and the electrode terminal connected to the outermost electrode, which is in direct contact with the laminate film, of the positive electrode or the negative electrode constituting the battery element. It is possible to judge from the resistance value observed by applying an appropriate voltage to a predetermined time. Specifically, as an example, a voltage of 25 V-2 sec is applied between the negative electrode terminal and the aluminum foil of the laminate film, and those having an insulation resistance of 90 MΩ or more are determined to be non-defective and those having a resistance of less than 90 MΩ are determined to be defective.

[Example 1]
Example 1 will be described below. Of the heater blocks in this embodiment, the heater block (first heater block) 8 for the terminal side 3a is shorter than the terminal side (short side) 3a as shown in FIGS. 3 (a) and 4 (a). The both sides of the terminal side 3a, that is, the portions facing the corners 12 of the exterior body 4 are removed, and the linear shape is 5 mm wide.

  As shown in FIGS. 3B and 4B, the heater block 9 for the side 3b (second heater block) 9 has substantially the same length as the side 3b and is a straight line having a width of 5 mm. It is. The second heater block 9 generates heat at a temperature lower than that of the first heater block 8. The second heater block 9 may have a configuration in which the portions facing the two side edges 3b are integrated by a connecting portion (not shown) at a position where the second heater block 9 does not contact the laminate film 2. Moreover, the structure which each above-mentioned part was respectively attached to the drive mechanism which is not shown in figure for making the 2nd heater block 9 approach to the laminate film 2, and operate | moved substantially integrally may be sufficient.

  A method for manufacturing the film-clad battery of Example 1 using these heater blocks 8 and 9 will be described.

  First, a single long laminate film 2 is prepared, and a plurality of negative electrodes 6 and positive electrodes 5 are alternately stacked on a part of the laminate film 2 with a separator 7 interposed therebetween to constitute a battery element 4. To do. Next, the laminate film 2 is folded in two to cover both surfaces of the battery element 4. The positive electrode terminal 5a connected to the positive electrode 5 of the battery element 4 and the negative electrode terminal 6a connected to the negative electrode 6 pass through the terminal side 3a from the connection portion with the battery element 4 to the outside not covered with the laminate film. Make it protruding. Then, the electrolyte solution 14 is injected between the two folded laminate films, and portions where the folded laminate films 2 are overlapped are thermally welded on three sides other than the folded portion 3c. Specifically, as shown in FIG. 4 (a), it is sufficient that the first heater block 8 (see FIG. 3 (a)) is brought into contact with the terminal side 3a and the heat radiation from the electrode terminal is taken into account. The laminate film 2 is heated at a relatively high temperature so that fusion occurs. Thereby, the part which contact | abuts the 1st heater block 8 of the laminate film 2 is heat-welded. The other portions are not welded at this time, and both side portions of the terminal side 3a, that is, the corner portions 12 do not come into contact with the first heater block 8, and remain unwelded. The order in which the thermal welding of the terminal side 3a, the thermal welding of the side 3b, and the injection of the electrolytic solution 14 of the laminate film 2 is performed appropriately so that the electrolytic solution 14 does not leak outside the exterior body 3. It is determined.

  Next, as shown in FIG. 4B, the laminate film 2 is heated by bringing the second heater block 9 into contact with the side 3b, and the contact portion is thermally welded. At this time, since it is not necessary to consider the heat radiation from the electrode terminals, the heater block 9 is set to a temperature lower than when the terminal side 3a is welded. In this way, both side portions of the terminal side 3a which has not been welded, that is, the corner portions 12 are also heated by the second heater block 9 and thermally welded.

  According to the manufacturing method of the first embodiment, when the first heater block 8 and the second heater block 9 are combined, the terminal side 3a and the two side sides 3b of the exterior material 3 are completely covered and fused. Further, the corner portion of the exterior material 3 is heated only by the second heater block 9 having a temperature lower than that of the first heater block.

  As described above, by using the heater blocks 8 and 9 to thermally weld the terminal side 3a and the side side 3b other than the bent portion 3c of the outer packaging material 3, the battery element 4 is enclosed and the peripheral edge portion is sealed. The outer packaging material 3 is formed, and the film outer battery 1 (see FIG. 1) is completed.

  Below, the width of the blocking region, the number of insulation failures, and the insulation failure rate were examined using 1000 pieces of the above-described film-clad battery 1 manufactured.

  Table 1 shows the evaluation results of the width of the blocking region, the number of insulation defects, and the insulation failure rate of the film-clad batteries of this example and the examples and comparative examples described later.

  When the film-clad battery manufactured in Example 1 was confirmed by the first visual evaluation method described above, all of the blocking regions 10b were small, specifically, the width inside the corner portion 12 was less than 3 mm. The width of other parts was less than 2 mm. Thereby, generation | occurrence | production of the crack of the laminated film 2, damage, and the insulation defect was suppressed. In addition, the width | variety of the heat welding part 10a was the same width as the heater block used over the whole exterior body 3. FIG. And when the area in the terminal side 3a was compared, the total area of the blocking area | region 10b was 1% or less of the total area of the heat welding part 10a.

[Comparative example]
Next, for comparison with Example 1, a heat welding method of a comparative example will be briefly described. Although not shown, the first heater block for the terminal side 3a of the laminate film 2 constituting the outer packaging material 3 of the comparative example is substantially the same length as the entire length of the terminal side 3a and has a straight line shape with no irregularities. And the 2nd heater block for the side 3b of a comparative example is the same length as the full length of the side 3b, and is a linear form without an unevenness | corrugation. Although not shown, the first heater block is brought into contact with the terminal side 3a and the laminate film 2 is heated to thermally weld the contact portion, and then the second heater block is brought into contact with the side 3b to laminate the film. 2 is heated and the contact part is heat-welded. According to this heat welding method, the corner portion 12 is in contact with the first heater block and is also in contact with the second heater block, so that the corner portion 12 is heated twice. One thousand film-coated batteries 1 were produced and evaluated in the same manner as in Example 1.

  In the film-clad battery created in the comparative example, a blocking region 10b having a width of 3 mm or more was generated between the heat-welded portion 10a and the unwelded portion 10c at the corner portion 12. Since the blocking region 10b is large in this way, the welded surface peeled off only by applying a small stress, and at that time, a crack occurred in the inner surface resin layer 2b of the laminate film 2, resulting in an insulation resistance failure.

  The reason why the blocking as described above occurs in the corner portion 12 is considered as follows.

  When welding the terminal side 3a, it is necessary to heat and heat the terminal side 3a to a temperature higher than that of the side side 3b in consideration of heat radiation from the electrode terminals 5a and 6a. In addition, when heated by the first heater block, the corner portion 12 is located away from the electrode terminal even though the temperature of the heater block is high. The strength of the film 2 is weakened. Further, the side 3b is damaged when it is fused. Accordingly, it is considered that residual heat is transmitted to the inner portion 13 of the corner portion 12 to cause blocking.

  As described above, in the film-clad battery 1 manufactured in the comparative example, the strength of the laminate film 2 is reduced or a defective insulation resistance is generated, so that the packaging material 3 cannot be sealed well.

[Example 2]
Next, a second embodiment of the present invention will be described. In the present embodiment, the shape of the first heater block 15 for heating the terminal side 3a and the shape of the second heater block 16 are different from those of the first embodiment. As shown in FIG. 6A, the first heater block 15 according to the present embodiment is provided at a position corresponding to a straight portion 15a shorter than the terminal side 3a and between the positive electrode terminal 5a and the negative electrode terminal 6a. It is a shape which has the protrusion part 15b which protrudes planarly toward the rectangular center part which is this planar shape. On the other hand, as shown in FIG. 6B, the second heater block 16 is connected to the straight line portion 16a having substantially the same length as the side 3b and the corner 12 where the terminal side 3a and the side 3b intersect. This is a shape having an extended portion 16b that extends in a plane toward the center of the side 3a and toward the center of the rectangle that is the planar shape of the exterior material 3.

  In the present embodiment, as in the first embodiment, as shown in FIG. 7A, the first heater block 15 is provided on the terminal side 3a in the portion where the two-fold laminate film 2 containing the battery element 4 overlaps. Contact and heat to heat-weld. Next, as shown in FIG.7 (b), the 2nd heater block 16 is contact | abutted to the both-sides 3b of the part which the two-fold laminated film 2 overlaps, and it heats and heat-welds. In the present embodiment, when heated by the first heater block 15, a wide range from the position between the positive electrode terminal 5 a and the negative electrode terminal 6 a on the peripheral edge of the terminal side 3 a to the position close to the battery element 4 by the protrusion 15 b. Heat. Further, during heating by the second heater block 16, a wide range from the corner portion 12 where the terminal side 3 a and the side side 3 b intersect to a position close to the corner portion of the battery element 4 is heated. Accordingly, the portion 11 between the positive electrode terminal 5a and the negative electrode terminal 6a and the inner portion 13 of the corner portion 12 are also sufficiently heated and thermally welded. That is, in these parts 11 and 13, the heat welding part 2a becomes wide, and between the heat welding part 2a and the unwelded part 2c (the part in which the laminate films 2 do not contact each other because the battery element 4 is interposed). Space is extremely small. Therefore, even if the blocking region 2b is generated between the heat-welded portion 2a and the non-welded portion 2c, the blocking region 2b is small, and there is little possibility that the laminate film 2 will be cracked, damaged or poorly insulated. When an experiment for producing 1000 pieces of the film-clad battery 1 was performed, the width of the blocking region 2b in the inner portion 13 of the corner portion 12 was less than 3 mm, and other portions, particularly the electrode terminals 5a and 6a on the terminal side 3a. The width of the blocking region 2b of the portion 11 located between the two is less than 2 mm, and the total area of the blocking region 2b in the terminal side 3a is 1% or less of the total area of the heat welded portion 2a, resulting in insulation failure. There wasn't. This is because most of the space in the portion 11 between the electrode terminals 5a and 6a and the inner portion 13 of the corner portion 12 where blocking is likely to occur is brought into contact with the first or second heat blocks 15 and 16. It is considered that the problem associated with blocking could be suppressed as a result of inevitably reducing the blocking region 2b by narrowing the region where blocking may occur by using the heat welded portion 2a to be heated.

  Temporarily, as shown in FIG. 8, the protrusion part 18a which is substantially the same length as the terminal side 3a, and is located between the positive electrode terminal 5a and the negative electrode terminal 6a, and the expansion part 18b located in the corner | angular part 12 are provided. When the terminal side 3a is heated using the first heater block 18 having, the portion 11 between the positive electrode terminal 5a and the negative electrode terminal 6a and the inner portion 13 of the corner portion 12 are heated and are not in an unwelded state. However, since the corner portion 12 is heated twice by the first heater block 18 and the second heater block 9 (see FIG. 3B), the corner portion 12 is overheated and greatly damaged, and the strength of the laminate film 2 is weak. Become.

[Examples 3 and 4]
As in the second embodiment, the area where the blocking may occur is narrowed by using most of the space in the position 11 between the electrode terminals 5a and 6a and the inner portion 13 of the corner portion 12 as the heat welding portion 2a. Examples 3 and 4 that can be performed will be described below. The difference between Example 3 and Example 4 and Example 2 is mainly the shape of the first heater block and the second heater block.

  In Example 3 of the present invention, as shown in FIG. 9, the first heater block 19 has a linear heater block 19a that is shorter than the terminal side 3a and has no unevenness, and a positive electrode terminal 5a and a negative electrode terminal 6a. The heater block 19b has a shape projecting in a plane toward the central portion of the rectangle, which is the planar shape of the exterior material 3, at the facing position. The heater block 19a generates heat at a higher temperature than the heater block 19b in consideration of heat radiation from the electrode terminals during welding. That is, the first heater block 19 of the present embodiment has a configuration in which the first heater block 8 of the first embodiment is divided into two portions 19a and 19b, and the respective heating temperatures are different.

  On the other hand, the second heater block for the side 3b is the same as the second heater block 16 of the second embodiment shown in FIG. 6B, and has a straight portion 16a having substantially the same length as the side 3b. And an extended portion 16b extending from the corner portion 12 toward the central portion side. The second heater block 16 generates heat at a temperature lower than that of the heater block 19a (may be the same heat generation temperature as the heater block 19b).

  In this embodiment, as shown in FIG. 10 (a), the laminate film 2 is heated at a relatively high temperature by bringing the heater block 19a (see FIG. 9) into contact with the terminal side 3a of the peripheral portion. Thereafter, the heater block 19b is brought into contact with the inside 11 of the peripheral portion and between the positive electrode terminal 5a and the negative electrode terminal 6a, and the laminate film 2 is heated at a relatively low temperature. Further, as shown in FIG. 10B, the laminate film 2 is heated at a relatively low temperature by bringing the second heater block 16 (see FIG. 6B) into contact with the side 3b. Thus, the contact portions of the laminate film 2 with the heater blocks 19 and 16 are thermally welded, and the exterior material 3 is sealed. In this example, the same effect as in Example 2 is obtained, and excessive heat is applied to the large area portion 11 between the positive electrode terminal 5a and the negative electrode terminal 6a inside the peripheral edge of the laminate film 2. It is possible to more reliably suppress damage. When an experiment for producing 1000 pieces of the film-clad battery 1 was performed, the width of the blocking region 2b in the inner portion 13 of the corner portion 12 was less than 3 mm, and other portions, particularly the electrode terminals 5a and 6a on the terminal side 3a. The width of the blocking region 2b of the portion 11 located between the two is less than 2 mm, and the total area of the blocking region 2b in the terminal side 3a is 1% or less of the total area of the heat welded portion 2a, resulting in insulation failure. There wasn't.

  Next, a fourth embodiment of the present invention will be described. As shown in FIG. 11A, the first heater block 20 of this embodiment includes a portion 20a facing the positive electrode terminal 5a and a portion 20b facing the negative electrode terminal 6a. The first heater block 20 heats the laminate film 2 at a relatively high temperature. The first heater block 20 may have a configuration in which the portions 20 a and 20 b are integrated by a connecting portion (not shown) at a position where the first heater block 20 is not in contact with the laminate film 2. Moreover, the structure by which each part 20a, 20b is each attached to the drive mechanism which is not shown in figure for making the 1st heater block 20 approach the laminate film 2, and is act | operated substantially integrally may be sufficient.

  As shown in FIG. 11B, the second heater block 21 of the present embodiment is similar to the straight portion 16a and the extended portion 16b of the second heater block 16 (see FIG. 6B) of the first embodiment. In addition to the part 21a and the extended part 21b, it has the heater block 21c located in the center part of the terminal side 3a, ie, between the positive electrode terminal 5a and the negative electrode terminal 6a. The second heater block 21 heats the laminate film 2 at a relatively low temperature. The second heater block 21 may have a configuration in which the portions 21a, 21b, and 21c are integrated by a connecting portion (not shown) at a position that does not contact the laminate film 2. Moreover, the structure by which each part 21a, 21b, 21c is each attached to the drive mechanism which is not shown in figure for making the 2nd heater block 21 approach the laminate film 2, and is act | operated substantially integrally may be sufficient.

  Accordingly, as shown in FIG. 12A, the heater block 20 is brought into contact with the portion of the terminal side 3a through which the positive electrode terminal 5a and the negative electrode terminal 6a penetrate, and the laminate film 2 in that portion is kept at a relatively high temperature. Heat and heat weld. Further, as shown in FIG. 12B, the heater block 21 is applied to the side 3b of the peripheral edge, and the peripheral edge between the positive terminal 5a and the negative terminal 6a of the terminal 3a and the inner portion 11 thereof. In contact, the laminate film 2 is heated at a relatively low temperature, and the heated portion is thermally welded. In this example, the same effect as in Example 1 is obtained, and the large area between the positive electrode terminal 5a and the negative electrode terminal 6a of the laminate film 2 is damaged by excessive heat, Furthermore, it can suppress reliably. When an experiment for producing 1000 pieces of the film-clad battery 1 was performed, the width of the blocking region 2b in the corner portion 12 was less than 3 mm, and was positioned between the other portions, particularly the electrode terminals 5a and 6a on the terminal side 3a. The width of the blocking region 2b of the part to be performed is less than 2 mm, and the total area of the blocking region 2b in the terminal side 3a is 1% or less of the total area of the heat-welded portion 2a, and no insulation failure occurred.

  In each of the embodiments described above, theoretically, the first heater block and the second heat block may be designed so that the heating portion by the first heat block and the heating portion by the second heat block do not overlap. It is considered preferable. However, in practice, in order not to leave an unheated portion at the peripheral edge of the laminate film 2, the first heater so that the heated portion by the first heat block and the heated portion by the second heat block slightly overlap each other. It is realistic that the block and the second heat block are designed. In that case, the first heater block and the second heat block are located so that the overlapping portion of the terminal side 3a is located at a position other than the corner portion 12, that is, between the corner portion 12 and the electrode terminals 5a and 6a. Preferably it is designed. This is because the portion heated twice by the first heater block and the second heater block is located in the vicinity of the electrode terminals 5a and 6a having a heat radiation action, so that damage due to overheating can be suppressed small. Moreover, since the part heated twice is a position of the terminal side 3a other than the corner | angular part 12, the peeling stress of the laminate film 2 by the reaction gas of the electrolyte solution 14 accommodated in the exterior material 3 is disperse | distributed. Insulation resistance failure can be suppressed.

  In each of the above-described embodiments, the long laminate film 2 is folded to form the exterior material 3, but the two laminate films 2 are overlapped with the battery element 4 sandwiched therebetween. 3 may be configured. In that case, since the peripheral portion of the other short side positioned instead of the bent portion is also heated and thermally welded, a heater block for heating the peripheral portion of the short side may be appropriately added.

1 Film exterior battery 2 Laminate film (film-like member)
DESCRIPTION OF SYMBOLS 3 Exterior material 3a Terminal edge 3b Side edge 3c Bending part 4 Battery element 5 Positive electrode 5a Positive electrode terminal 6 Negative electrode 6a Negative electrode terminal 7 Separator 8 1st heater block 9 2nd heater block 10a Thermal welding part 10b Blocking area | region 10c Unwelded part 11 Electrode Part 12 between terminals 12 Corner part 13 Inner part 14 of corner part Electrolyte solution 15, 15a, 15b 1st heater block 16, 16a, 16b 2nd heater block 19, 19a, 19b 1st heater block 20, 20a, 20b First heater block 21, 21a, 21b, 21c Second heater block

Claims (7)

A battery element having a configuration in which a positive electrode and a negative electrode are stacked via a separator is housed in an exterior material made of a film-like member, and the exterior material is sealed,
The exterior material has at least one terminal side and a side side,
An electrode terminal is connected to each of the positive electrode and the negative electrode, and the electrode terminal protrudes to the outside through the terminal side from the inside of the exterior material,
Among the overlapping portions of the film-like members that respectively cover both surfaces of the battery element, the width of the blocking region located inside the corner where the terminal side and the side side intersect is less than 3 mm. A featured film-clad battery.   The film-clad battery according to claim 1, wherein a width of a blocking region located between the plurality of electrode terminals on the terminal side is less than 2 mm.   The film-clad battery according to claim 1 or 2, wherein the film-like member is heated and thermally welded at the same temperature on the terminal side and the side side.   Of the overlapping portions of the film-like member, the portion heated twice and thermally welded is located between the portion of the terminal side overlapping the electrode terminal and the corner portion. The film-clad battery according to any one of claims 1 to 3. In a method for producing a film-clad battery, in which a battery element having a configuration in which a positive electrode and a negative electrode are laminated via a separator is housed in a bag-shaped exterior material made of a film-like member, and the exterior material is sealed There,
Covering both surfaces of the battery element with the film-like member, and the electrode terminals respectively connected to the positive electrode and the negative electrode pass through the terminal sides of the film-like member and project to the outside;
A first heater block is disposed in a portion of the film-like member excluding both ends of the terminal side, and the film-like member that covers both surfaces of the battery element overlaps each other at a contact portion with the first heater block. Heating and thermally welding the peripheral edge by the first heater block;
The second heater block is arranged at a position including the both end portions of the terminal side of the film-like member and the side sides other than the terminal side, and the first of the film-like member covering both surfaces of the battery element, respectively. Heating and heat-welding the peripheral portions that overlap each other at the contact portion with the two heater blocks by the second heater block;
Including
The step of heat-welding by heating by the first heater block and the step of heat-welding by heating by the second heater block are performed by heating the film-like member at the same temperature and heat-welding. Method. In a method for producing a film-clad battery, in which a battery element having a configuration in which a positive electrode and a negative electrode are laminated via a separator is housed in a bag-shaped exterior material made of a film-like member, and the exterior material is sealed There,
Covering both surfaces of the battery element with the film-like member, and the electrode terminals respectively connected to the positive electrode and the negative electrode pass through the terminal sides of the film-like member and project to the outside;
A first heater block is disposed in a portion of the film-like member excluding both ends of the terminal side, and the film-like member that covers both surfaces of the battery element overlaps each other at a contact portion with the first heater block. Heating and thermally welding the peripheral edge by the first heater block;
The second heater block is arranged at a position including the both end portions of the terminal side of the film-like member and the side sides other than the terminal side, and the first of the film-like member covering both surfaces of the battery element, respectively. Heating and heat-welding the peripheral portions that overlap each other at the contact portion with the two heater blocks by the second heater block;
Including
Either the step of heating and heat-welding with the first heater block or the step of heating and heat-welding with the second heater block includes the film-like member inside the peripheral edge and between the electrode terminals. Heating and heat welding
The step of heating and welding by the second heater block includes the film-like member inside the peripheral edge and inside the corner where the terminal side and the side of the film-like member intersect. A method for producing a film-sheathed battery, comprising heating and heat-welding the film.   A plane of a side of the film-like member through which the electrode terminal passes through a portion where the portion heated by the first heater block and the portion heated by the second heater block of the film-like member overlap each other. The method for manufacturing a film-clad battery according to claim 5 or 6, wherein the film-covered battery is positioned between a portion that overlaps the electrode terminal and a corner portion where the terminal side and the side side intersect.