TW201624815A - Manufacturing method of battery - Google Patents

Abstract

The invention provides a manufacturing method of battery with features in comprising: preparing step, arranging battery body 23 in interior of plane rectangular bag while three edges of four edges near circumference of battery body in the bag are blocked, a part of remained edge portion 34 forms an opening portion 24 so as to acquire temporary seal device 30; inflow step, disposing temporary seal device as opening portion 24 upright and upward while electrolyte is injected into a position right above opening portion 24 by terminal configuration of nozzle 40 for electrolyte injection or configured to insert opening portion 24 for injecting electrolyte into the battery body 23; a first sealing step, forming a first heat sealing portion by using a first heat sealing rod to heat seal opening portion 24 during deaeration in temporary sealing device after injection; and a second sealing step, using a second heat sealing rod to perform hot pressing for the first sealing portion after completion of deaeration. Through this manufacturing method, battery with excellent production performance and sufficient sealing strength for preventing interlamination peeling occurring at heat sealing location can be manufactured.

Description

Battery manufacturing method

The present invention relates to a method for producing a laminated secondary battery of a laminated lithium ion secondary battery in which an exterior material is laminated.

In recent years, it has become thinner and lighter in portable devices such as smart phones and tablet terminals, and is used as a power storage device such as a lithium ion battery, a lithium polymer battery, a lithium ion capacitor, or an electric double layer capacitor mounted on such devices. The exterior material is currently using a heat-resistant resin layer/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer (inner layer) to form a laminate instead of the conventional metal can.

The manufacturing method of the external material is such that the lithium battery main body is housed and has an opening portion in a part thereof, and at least the base layer, the aluminum foil, the chemical conversion treatment layer, and the thermal adhesive resin layer are sequentially laminated. The method for heat-sealing the opening of the lithium battery exterior body formed by the elastic exterior material, the conventional method for heat sealing the lithium battery exterior body includes the first step of forming the inner layer The temperature of the melting point of the thermal adhesive resin is heated and dried to be the position of the heat sealing portion of the opening portion; and in the second step, the opening portion is thermally sealed by the heat to heat the sealing portion to heat-sealing (refer to the patent) Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-261033

However, in the above method, before the second step of heat sealing, the first step of heating and drying the electrolytic solution attached to the predetermined sealing position is provided, so that the productivity is inferior. In particular, since the temperature of the melting point of the thermal adhesive resin which does not form the inner layer is used for heating and drying the adhering electrolyte, it takes time to perform only heat drying.

Further, the longer the time of heating and drying by vacuum, the more the amount of the electrolytic solution is scattered and adhered to the predetermined portion of the heat seal, so that the amount of the electrolyte inclusions in the heat seal portion increases.

The present invention has been made in view of the above technical background, and an object of the invention is to provide a method for producing a battery, which is capable of ensuring sufficient sealing strength to prevent interlayer peeling at a heat sealing position and having excellent productivity.

To achieve the foregoing objects, the present invention provides the following means.

[1] A method of producing a battery, characterized in that it comprises: a preparation step of forming a heat-resistant resin layer as an outer layer, a thermoplastic resin layer as an inner layer, and an outer material of a metal foil layer disposed between the two layers into a rectangular body having a rectangular shape in plan view And arranging the battery body portion inside the bag body, and sealing three of the four sides of the bag body in the vicinity of the periphery of the battery body portion, and simultaneously forming the opening portion of the remaining one side portion with the opening portion a temporary sealing element; the injection step of disposing the temporary sealing element in a state in which the opening is opened upward toward the upper opening, and arranging the tip end of the electrolyte injection nozzle so as to be located directly above the opening or as Inserting the electrolyte into the battery main portion by inserting the opening; the first sealing step is performed by using a deaerator inside the temporary sealing element after the injection step, and heat sealing using the first heat sealing rod while degassing a first sealing portion is formed in the opening portion; and a second sealing step is performed after the degassing is completed, and the first sealing portion is heated by using a second heat sealing rod By.

[2] The method for producing a battery according to the first aspect, wherein the temperature of the first heat sealing rod when the heat sealing is performed in the first sealing step is set to a temperature equal to or higher than a melting point of the thermoplastic resin layer; The temperature of the second heat sealing rod when the heat sealing is performed in the second sealing step is set to a temperature equal to or higher than the melting point of the thermoplastic resin layer.

[3] The method of producing a battery according to the above aspect, wherein the thermoplastic resin layer of the temporary sealing element comprises a low-melting thermoplastic resin layer disposed on the inner surface side and disposed on the metal foil layer side. a multilayer structure of a high-melting-point thermoplastic resin layer; the temperature of the first heat-sealing rod when heat-sealing in the first sealing step is set a temperature above the melting point of the low melting point thermoplastic resin layer; The temperature of the second heat sealing rod when heat sealing is performed in the second sealing step is set to a temperature equal to or higher than the melting point of the low melting point thermoplastic resin layer.

[4] The method for producing a battery according to any one of the preceding claims, wherein, in the first sealing step and/or the second sealing step, a pair of heat sealing rods are used for the inner contact surface, and The heat sealing rod is formed by a curved shape that protrudes in a central portion of the heat sealing rod in the longitudinal direction or/and the lateral direction.

[5] The method for producing a battery according to any one of the preceding claims, wherein, in the first sealing step and/or the second sealing step, a pair of porous sheets are disposed on the inner contact surface. Heat sealing rod.

[6] The method for producing a battery according to any one of the preceding claims, wherein the one of the three sides sealed in the temporary sealing element is sealed by a bent portion, and the bent portion is sealed. The inner layer of the exterior material is placed on the inner side and formed by folding twice.

According to the invention of [1], since the heat sealing (final heat sealing) of the one side portion (opening portion) remaining on the temporary sealing member is carried out in plurals of two or more times, one of the conventional methods can be used. The time required for the final heat sealing (N seconds) is individually assigned to the first sealing step and the second sealing step, so that the individual heat sealing time of the first sealing step and the second sealing step can be less than N seconds (for example, , 0.5 N seconds, 0.7 N seconds, 0.8 N seconds, etc.), whereby the step time can be shortened, thereby improving productivity. For example, use a degassing device or the like to make the first After the sealing step is completed in the shortening time, the temporary sealing member after the completion is transferred to the subsequent second sealing step, and the first sealing step is performed on the following work (temporary sealing member) by the deaerator or the like. The step time can be shortened (the tact time equivalent to 1 step can be shortened).

In addition, since the conventional method performs one-time final heat sealing, a long heat sealing time is required, and therefore heat (temperature) transmitted to the main body portion of the battery is large, and there are doubts such as decomposition of the electrolyte and deterioration of the performance of the electrolyte. . On the other hand, in the present invention, since the heat seal is divided into two or more times, the heat (temperature) transmitted to the main body of the battery or the like is not excessively large, so that the decomposition of the electrolytic solution and the deterioration of the performance of the electrolytic solution are not caused. .

Further, since the heat-sealing system is divided into two or more plural times, the time (degassing time) of the first sealing step of performing heat sealing while deaeration can be set to be short, and the degassing can be reduced when deaerating The amount of the electrolyte adhering to the opening of the predetermined portion of the seal is obtained to achieve better heat-sealed joint (ensure sufficient sealing strength) and prevent delamination of the seal portion from occurring.

Further, since the heat sealing system is divided into two or more plural times, for example, the sealing device of the first sealing step (the sealing device provided with the deaeration device) and the sealing device of the second sealing step can be individually customized, thereby In the two sealing steps, the conditions can be set differently, and since the two sealing steps can be set to individual optimum conditions, it is possible to manufacture a battery having excellent reliability.

According to the invention of [2], it is possible to ensure further sufficient sealing strength, and it is possible to sufficiently prevent the occurrence of interlayer peeling of the sealing portion.

According to the invention of [3], it is possible to improve the heat-sealing property of the first sealing step of heat-sealing while deaeration, and to prevent the occurrence of cracks and deformation of the heat-sealed portion. Health.

According to the inventions of [4] and [5], even if the electrolytic solution adheres to the predetermined opening of the heat seal and/or the inside of the first sealing portion, the electrolyte can be sealed to the peripheral side while being sealed. A high sealing strength is ensured to achieve further good heat sealing engagement, and the occurrence of interlayer peeling of the sealing portion can be sufficiently prevented.

According to the invention of [6], in the step of preparing the temporary sealing member, since one of the three sides to be sealed is not sealed, but is formed by sealing the bent portion of the second folding, It can further improve productivity.

1‧‧‧External materials

2‧‧‧Heat resistant resin layer (outer layer)

3‧‧‧ thermoplastic resin layer (inner layer)

4‧‧‧metal foil layer

10‧‧‧Battery

21‧‧‧ Front part of exterior material

22‧‧‧The back part of the exterior material

23‧‧‧Battery body

24‧‧‧ openings

27‧‧‧2nd adjacent edge seal (complex back seal)

30‧‧‧ Temporary sealing element

31‧‧‧Folding edge (bending part)

32‧‧‧ opposite sides

33‧‧‧1st adjoining edge

34‧‧‧2nd adjoining edge

35‧‧‧ opposite edge seal

36‧‧‧1st adjacent edge seal

40‧‧‧Electro injector injection nozzle

43‧‧‧Heat seal rod

44‧‧‧Contact surface

46‧‧‧Heat seal rod

48‧‧‧ porous tablets

Fig. 1 is a front view showing a half step before the manufacturing method of the present invention, wherein (A) shows that the upper side (second adjacent side) of the four sides in the vicinity of the periphery of the battery main portion has an opening portion and is heat-sealed. (B) is a state in which an electrolyte solution is injected using an electrolyte injection nozzle; (C) is a state in which an opening of an upper end of the gas chamber is heat-sealed to form a sealed bag.

Fig. 2 is a front view showing a half step of the manufacturing method of the present invention, wherein (A) shows a state in which an electrode material is impregnated with an electrolytic solution by a chemical conversion treatment; (B) shows a second sealing step and a second step. The sealing step forms the second adjacent side seal portion to complete the sealed state, and (C) shows the state in which the gas chamber portion is removed by trimming to obtain a laminated battery.

Fig. 3 is a cross-sectional view showing a state in which heat sealing is performed using a pair of heat sealing bars.

Fig. 4 is a cross section showing another example of a state in which heat sealing is performed using a pair of heat sealing bars. Figure.

Fig. 5 is a cross-sectional view showing an example of a material other than the production method of the present invention.

A method of manufacturing the battery of the present invention will be described with reference to the drawings. The exterior material 1 used in the production method of the present invention uses a heat-resistant resin layer 2 as an outer layer, a thermoplastic resin layer 3 as an inner layer, and a metal foil layer 4 disposed between the two layers. Loading (refer to Figure 5). For example, a surface on one side of the metal foil layer 4 is integrated with the heat-resistant resin layer (outer layer) 2 by the first adhesive layer 5, and the other surface of the metal foil layer 4 is passed through the second surface. The adhesive layer 6 and the thermoplastic resin layer (inner layer) 3 are laminated and integrated (see FIG. 5).

The thermoplastic resin layer 3 may be formed of a single layer or may be formed of a plurality of layers. In particular, the thermoplastic resin layer 3 preferably includes a low-melting thermoplastic resin layer disposed on the inner surface side and disposed on the metal foil layer 4 side (closer to the metal foil layer 4 than the low-melting thermoplastic resin layer) The high-melting point thermoplastic resin layer of the side) is composed of a plurality of layers of two or more layers. The low melting point thermoplastic resin layer and the high melting point thermoplastic resin layer will be described in detail later. The "low-melting thermoplastic resin" means a thermoplastic resin having a melting point of 120 ° C to 155 ° C, and the "high-melting thermoplastic resin" means a thermoplastic resin having a melting point higher than that of the low melting point resin. The high melting point resin has a melting point higher than the melting point of the low melting point thermoplastic resin, and the melting point of the high melting point resin is preferably 135 ° C to 185 ° C.

The battery main body portion 23 is disposed in the outer casing 1 formed by the above configuration. The inside of the bag body having a rectangular shape in plan view is sealed, and three sides 31, 32, and 33 of the four sides of the periphery of the battery main body portion 23 in the bag body are sealed, and one side portion 34 is left on the one side portion 34. The opening portion 24 is formed by unsealing and joining the outer surface front portion 21 and the outer material rear surface portion 22, thereby forming the temporary sealing member 30 (see FIG. 1(A)).

The temporary sealing member 30 is formed by folding the inner layer 3 as an inner side in the longitudinal direction intermediate position of the outer casing 1 having a rectangular shape and having a rectangular shape, thereby forming a substantially rectangular outer casing front portion 21, and The battery main body portion 23 having a rectangular shape in plan view is disposed between the outer surface front portion 21 and the slightly rectangular outer material rear surface portion 22. In Fig. 1, 31 is a folded side (bending portion). The battery main body portion 23 is disposed in a slightly lower half of a space between the outer surface front portion 21 and the outer material rear surface portion 22 (see FIG. 1(A)). The outer surface front portion 21 and the outer material rear surface portion 22 are joined to each other by the heat sealing or the like in the opposing side portion 32 opposed to the folded side 31 of the second folding, thereby forming the opposite side sealing portion 35. .

The positive electrode tab 11 and the negative electrode tab 12 extend outward from one side (opposing side portion) 32 of the battery main body portion 23 (see FIG. 1(A)). Therefore, in the present embodiment, in the opposite side portion 32, the outer surface front portion 21 and the outer material rear surface portion 22 are sandwiched between the positive electrode tab 11 and the negative electrode tab 12 and joined by heat sealing or the like. Thereby, the opposite side seal portion 35 is formed (see FIG. 1(A)). The tip end portion of the positive electrode tab 11 is led to the outside, and the tip end portion of the negative electrode tab 12 is led to the outside. The battery main body portion 23 includes components such as a positive electrode material, a negative electrode material, and an electrolytic solution. However, in this stage, the electrolyte solution is not injected. The positive electrode material is connected to the positive electrode tab 11 and the negative electrode material is connected to the negative electrode tab 12.

In the bag body, among the four sides 31, 32, 33, and 34 in the vicinity of the periphery of the battery main body portion 23, the first adjacent side adjacent to the folded side 31 is thermally sealed or the like. The exterior material front portion 21 of the portion 33 is joined to the exterior material back surface portion 22 to form a first adjacent side seal portion 36 (see Fig. 1(A)). Further, in the bag body, among the four sides 31, 32, 33, and 34 in the vicinity of the periphery of the battery main body portion 23, the second adjacent side portion 34 adjacent to the other side of the folded side 31 is formed with an opening portion 24 ( Refer to Figure 1 (A)). In FIG. 1, the internal space 41 in the temporary sealing element 30 above the second adjacent side portion 34 is referred to as a "gas chamber".

Then, as shown in FIG. 1(B), the temporary sealing member 30 is disposed such that the second adjacent side portion 34 is placed upright from the first adjacent side portion 33, that is, the temporary sealing member 30 is placed. The opening portion 24 is disposed so as to be upright from the first adjacent side seal portion 36, and is placed at the tip end of the electrolyte injection nozzle 40 at a position directly above the opening portion 24, or as shown in FIG. (B), the opening 24 is inserted into the opening, and the electrolyte is injected into the battery main portion 23 (injection step).

The electrolytic solution is not particularly limited, and for example, a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1 is mixed, and a lithium hexafluorophosphate salt is dissolved in a solution having a concentration of 1 mol/L. (electrolyte), etc.

Next, the opening of the upper end of the gas chamber 41 in the temporary sealing member 30 is heat-sealed, and the gas chamber upper end sealing portion 37 is formed to form a sealed bag (see FIG. 1(C)).

In the above-described injection step and the above-described sealed bag forming step, in order to minimize the residual moisture in the obtained laminated battery and to increase the life of the laminated battery, it is preferable to carry out the drying in the drying chamber. The conditions in the drying chamber include, for example, a range of dew point "-40 ° C" to "-60 ° C".

Next, the aforementioned sealed bag (temporary sealing member) 30 is placed into a processing capacity. In the chemical conversion processing, the electrode material (the positive electrode material and the negative electrode material) is impregnated with the electrolytic solution (chemical conversion processing step) (see FIG. 2(A)). The chemical conversion treatment may be, for example, the following treatment. First, after leaving at room temperature, the viscosity of the electrolyte is lowered by placing it in an environment of 40 ° C to 60 ° C to diffuse (soak) the electrolyte into the electrode material (electrode active material, etc.). Next, pressure is applied from the top surface of the laminated battery equivalent portion, initial charging, and pressurized degassing in an environment of high temperature (40 ° C to 60 ° C).

After that, the inside of the sealed bag (temporary sealing member) 30 is degassed (vacuum degassing, etc.) using a deaerator, and the second heat sealing rod is used for the second of the sealed bags (temporary sealing elements) 30. The opening (heat sealing predetermined portion) 24 of the adjacent side portion 34 is heat-sealed to form a first sealing portion (first sealing step). The heat sealing time in the first sealing step is not particularly limited, but is preferably set to 4 seconds to 8 seconds.

Then, after the first sealing step, that is, after the completion of the degassing, the first sealing portion is heated and pressurized by the second heat sealing rod to form a second adjacent side sealing portion (plural return sealing portion) 27 ( Referring to Fig. 2(B)), the sealing of the exterior material 1 is completed (second sealing step). The heat sealing time in the second sealing step is not particularly limited, but is preferably set to 3 seconds to 9 seconds.

In the first sealing step, the temperature of the first heat sealing rod when the opening portion 24 is heat-sealed is preferably set to a temperature equal to or higher than the melting point of the thermoplastic resin constituting the thermoplastic resin layer 3 (the same temperature as the melting point). Or a higher temperature than the melting point). The temperature of the first heat-sealing rod is particularly preferably set to a temperature higher by 10 ° C to 40 ° C than the melting point of the thermoplastic resin constituting the thermoplastic resin layer 3 . In the second sealing step, the temperature of the second heat sealing rod when heated and pressurized is preferably set to the thermoplastic resin constituting the thermoplastic resin layer 3. The temperature above the melting point (the same temperature as the melting point or a higher temperature than the melting point). The temperature of the second heat-sealing rod is particularly preferably set to a temperature higher by 10 ° C to 40 ° C than the melting point of the thermoplastic resin constituting the thermoplastic resin layer 3 .

In addition, the thermoplastic resin layer 3 is disposed on the side of the metal foil layer 4 (including the low-melting thermoplastic resin layer disposed on the inner surface side) and closer to the metal foil layer 4 side than the low-melting thermoplastic resin layer. When the plurality of layers of the high melting point thermoplastic resin layer are composed of two or more layers, it is preferable to set the following conditions in the first sealing step and/or the second sealing step. In other words, in the first sealing step, the temperature of the first heat sealing rod when heat sealing is preferably set to a temperature equal to or higher than the melting point of the low melting point thermoplastic resin layer (the same melting point as the low melting thermoplastic resin layer) The temperature or the temperature at which the melting point of the lower melting thermoplastic resin layer is high). The temperature of the first heat sealing rod is preferably set to a temperature at which the melting point of the lower melting thermoplastic resin is higher by 10 ° C to 40 ° C. Further, in the second sealing step, the temperature of the second heat sealing rod at the time of heating and pressurization is preferably set to a temperature equal to or higher than the melting point of the low melting point thermoplastic resin (the same temperature as the melting point of the low melting point thermoplastic resin or The lower melting point of the thermoplastic resin has a higher melting point). The temperature of the second heat-sealing rod is preferably set to a temperature at which the melting point of the lower melting thermoplastic resin is higher by 10 ° C to 40 ° C.

In the first sealing step and the second sealing step, the heat sealing rod is preferably a heat sealing rod as shown in Figs.

In the heat sealing rod 43 shown in Fig. 3, the inner contact surface 44 is formed by a curved shape that protrudes in the center portion of the heat sealing rod in the longitudinal direction (the center portion is convex). When the heat-sealing rod 43 is heat-sealed to the opening portion 24 of the second adjacent side portion 34, the electrolyte solution may be adhered to the opening portion 24 that is heat-sealed. The heat sealing joint is performed while flowing to the peripheral side, thereby ensuring high sealing strength. The heat seal rod 43 may be formed by a curved shape that protrudes in a central portion in the width direction of the heat seal rod (the center portion is convex). Further, the heat seal rod 43 may be formed by a curved shape that protrudes in the center portion of the heat seal rod in the longitudinal direction and the width direction (the center portion is convex). The curved shape is not particularly limited, and examples thereof include an arc shape and the like.

Further, the heat sealing rod 46 shown in Fig. 4 is provided with a porous sheet 48 on the inner contact surface. In the present embodiment, both end portions of the porous sheet 48 are individually fixed to both side faces of the heat sealing rod 46. When the heat-sealing rod 46 is heat-sealed to the opening 24 of the second adjacent side portion 34, the electrolyte may flow to the peripheral side even if the electrolyte is adhered to the predetermined opening portion 24 by heat sealing. At the same time, heat sealing is performed to ensure high sealing strength. The porous sheet 48 is not particularly limited, and examples thereof include a mesh sheet, a glass cloth sheet, a nonwoven fabric sheet, and an embossed sheet. The material of the mesh sheet, the nonwoven fabric sheet, and the embossed sheet is not particularly limited, and examples thereof include a polyester resin, a polyimide resin, a fluororesin (such as polytetrafluoroethylene), and glass (glass cloth, etc.). And composite materials such as fluororesin (polytetrafluoroethylene, etc.).

Next, the portion (slightly upper half) corresponding to the gas chamber 41 in the sealed bag 30 is removed by trimming, and the laminated battery 10 shown in Fig. 2(C) is obtained. In the laminated battery 10, all of the four sides 31, 32, 33, and 34 in the vicinity of the periphery of the battery main portion 23 in the exterior body 1 are sealed (see Fig. 2(C)).

Next, the exterior material 1 used in the production method of the present invention will be described in detail.

The heat-resistant resin constituting the heat-resistant resin layer (outer layer) 2 is a heat-resistant resin that does not melt at the heat sealing temperature when the exterior material is heat-sealed. The aforementioned heat resistance tree The grease is preferably a heat-resistant resin having a melting point higher than a melting point of the thermoplastic resin constituting the thermoplastic resin layer 10 by 10 ° C or more, and a heat-resistant resin having a melting point higher than a melting point of the thermoplastic resin by 20 ° C or more. It is better. In particular, the heat-resistant resin is preferably a heat-resistant resin having a high melting point higher than a melting point of a thermoplastic resin constituting the thermoplastic resin layer 3 by a temperature of 40 ° C, and particularly preferably has a higher melting point than the thermoplastic resin. A heat-resistant resin having a high melting point at a temperature of 50 °C.

In addition, when the thermoplastic resin layer 3 includes a low-melting thermoplastic resin layer disposed on the inner surface side and a high-melting thermoplastic resin layer disposed on the metal foil layer 4 side, the heat-resistant resin is used. The heat-resistant resin having a melting point higher than the melting point of the low-melting thermoplastic resin constituting the thermoplastic resin layer 3 by 10 ° C or more is preferable, and the heat-resistant resin having a melting point lower than the melting point of the thermoplastic resin having a melting point of 20 ° C or higher is used. It is better. In particular, the heat-resistant resin is preferably a heat-resistant resin having a high melting point higher than a melting point of a low-melting thermoplastic resin constituting the thermoplastic resin layer 3 by a temperature of 40 ° C, and particularly preferably has a lower melting point thermoplasticity. A heat-resistant resin having a high melting point of 50 ° C or higher in melting point of the resin.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include a polyamide film such as a nylon film, a polyester film, and the like, and such a stretched film can be preferably used. In the heat-resistant resin layer 2, a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, and a biaxially oriented polyterephthalic acid are used. A glycol ester (PET) film or a biaxially stretched polyphthalic acid (PEN) film is particularly preferred. The nylon film is not particularly limited, and examples thereof include a nylon film, a 6,6 nylon film, and an MXD nylon film. Further, the heat resistant resin layer 2 may be formed of a single layer, or may be a plurality of layers (PET film / film) composed of, for example, a polyester film/polyamide film. A plurality of layers of a nylon film are formed, etc.).

The thickness of the heat resistant resin layer 2 is preferably 5 μm to 80 μm. By setting the above lower limit value or more, it is possible to ensure sufficient strength of the packaging material, and by setting it below the above preferred upper limit value, it is possible to reduce stress during molding such as bulging molding or deep drawing molding. Improve formability.

The thermoplastic resin layer (inner layer) 3 is excellent in chemical resistance even when it is used in an electrolytic solution or the like which is highly corrosive to a lithium ion battery or the like, and is also responsible for imparting heat sealing properties to the packaging material.

The thermoplastic resin layer 3 is not particularly limited, but is preferably a thermoplastic resin which does not have a film layer. The thermoplastic resin-free unstretched film layer 3 is not particularly limited, and is thermoplastic in at least one selected from the group consisting of polyethylene, polypropylene, olefin-based copolymers, acid-modified materials, and ionic polymers. It is preferred that the unstretched film composed of the resin is formed.

The thermoplastic resin layer 3 preferably includes a low-melting thermoplastic resin layer disposed on the inner surface side and disposed on the metal foil layer 4 side (closer to the metal foil layer 4 than the low-melting thermoplastic resin layer) The high-melting-point thermoplastic resin layer is composed of a plurality of layers of two or more layers. In this case, the low-melting-point thermoplastic resin layer is not particularly limited, and examples thereof include polypropylene, polyethylene, propylene-ethylene copolymer (atactic polypropylene), olefin-based copolymer, and the like. The high melting point thermoplastic resin layer is not particularly limited, and examples thereof include homopolypropylene, polyethylene, propylene-ethylene copolymer (random polypropylene), olefin copolymer, and the like. Acid denatured bodies, ionomers, and the like.

The thickness of the thermoplastic resin layer 3 is preferably set to 20 μm to 80 μm. By setting it at 20 μm or more, the pinhole can be sufficiently prevented while setting Below 80 μm, the amount of resin can be reduced to achieve a cost reduction. Among them, it is particularly preferable that the thickness of the thermoplastic resin layer 3 is set to 30 μm to 50 μm. Further, the thermoplastic resin layer 3 may be a single layer or a plurality of layers.

The metal foil layer 4 is responsible for imparting gas barrier properties to the outer packaging material 1 to prevent oxygen or moisture from entering. The metal foil layer 4 is not particularly limited, and examples thereof include an aluminum foil, a copper foil, and a SUS foil (stainless steel foil). Generally, an aluminum foil or a SUS foil is used. The material of the aluminum foil is preferably an O material of A8079 or an O material of A8021. The thickness of the metal foil layer 4 is preferably 15 μm to 80 μm. When the thickness is 15 μm or more, the production of the metal foil can prevent the occurrence of the pinholes which are delayed, and at the same time, when the thickness is 80 μm or less, the stress at the time of molding such as bulging or deep drawing can be reduced to improve the formability.

It is preferable that the metal foil layer 4 is subjected to a chemical conversion treatment at least on the inner surface (the surface on the second adhesive layer 6 side). By performing such a film formation treatment, it is possible to sufficiently prevent corrosion of the surface of the metal foil caused by the contents (electrolyte of the battery, etc.). For example, the metal foil can be processed into a film by performing the treatment described below. In other words, for example, an aqueous solution of any one of the following 1) to 3) can be applied to the surface of the metal foil subjected to the degreasing treatment, and then dried to carry out chemical conversion treatment.

1) an aqueous solution containing a mixture of at least one compound selected from the group consisting of a metal salt of phosphoric acid, chromic acid, a fluoride, and a non-metal salt of a fluoride

2) Contains phosphoric acid, acrylic resin, chitosan derivative resins And an aqueous solution of at least one resin selected from the group consisting of phenolic resins and a mixture of at least one compound selected from the group consisting of chromic acid and chromium (III) salts

3) a resin containing at least one selected from the group consisting of phosphoric acid, an acrylic resin, a chitosan derivative resin, and a phenol resin, and at least one selected from the group consisting of chromic acid and chromium (III) salt. An aqueous solution of a mixture of a compound and a compound selected from the group consisting of a metal salt of a fluoride and a non-metal salt of a fluoride.

In the chemical conversion film, the amount of chromium adhesion (each side) is preferably 0.1 mg/m ² to 50 mg/m ² , and 2 mg/m ² to 20 mg/m ² is particularly preferable.

The first adhesive layer 5 is not particularly limited, and examples thereof include a polyurethane adhesive layer, a polyester urethane adhesive layer, and a polyether urethane adhesive layer. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. In particular, the thickness of the first adhesive layer 5 is preferably 1 μm to 3 μm from the viewpoint of thinning and weight reduction of the exterior material.

Although the second adhesive layer 6 is not particularly limited, for example, the above-described first adhesive layer 5 can be used, but a polyolefin-based adhesive which is less likely to swell by the electrolytic solution is preferably used. The thickness of the second adhesive layer 6 is preferably set to 1 μm to 5 μm. In particular, the thickness of the second adhesive layer 6 is particularly preferably 1 μm to 3 μm from the viewpoint of thinning and weight reduction of the exterior material.

In the manufacturing method of the present invention, the exterior material 1 can be used by forming (deep stretching) The molded case (the outer case that can accommodate the shape of the battery main body portion 23) formed by molding, bulging, or the like can be used as it is without being formed.

In the above embodiment, the temporary sealing member 30 is formed by folding one exterior material 1 twice, but the configuration is not particularly limited. For example, the inner layers 3 of the two exterior materials 1 may be used. The temporary sealing member 30 is formed as an inner surface (the individual inner layers 3 are in contact with each other).

[Examples]

Next, specific examples of the invention will be described, but the invention is not particularly limited to the examples.

<Example 1>

On both surfaces of an aluminum foil (A8021-O material) 4 having a thickness of 35 μm, a chemical conversion coating liquid formed of phosphoric acid, polyacrylic acid, a trivalent chromium compound, water, or an alcohol is applied, and dried at 180 ° C to form a chemical conversion film. Membrane. The amount of chromium deposited on the film was 10 mg/m ^{2 on} one side.

Next, on the surface on one side of the aluminum foil 4 on which the film formation process is completed, a two-liquid-stretched urethane-based adhesive (first adhesive layer) 5 and a biaxially oriented poly-p-benzene having a thickness of 25 μm are used. A polyethylene diester (PET) film (melting point: 230 ° C) 2 was subjected to dry lamination (bonding).

Next, the adhesive liquid was applied onto the other surface of the aluminum foil 4 using a gravure roller, and then dried at 80 ° C in hot air to form a resin layer (second adhesive layer) 6 having a thickness of 3 μm. The above solvent solution is a mixed solvent (toluene/methyl ethyl ketone = 8 parts by mass) /2 parts by mass of a mixed solvent) 85 parts by mass of a maleic acid-modified polypropylene (a copolymer of propylene and ethylene and a maleic anhydride graft-polymerized to a denatured polypropylene resin; a dissolution temperature of 80 ° C) 15 parts by mass, and It was mixed with 0.9 parts by mass of a polymer of hexamethylene diisocyanate to form an adhesive liquid.

Next, an ethylene-propylene copolymer resin layer (low-melting point thermoplastic resin layer) 3 having a melting point of 145 ° C and a thickness of 20 μm, and a homopolypropylene resin layer having a melting point of 165 ° C and a thickness of 20 μm were used by using a T-die ( After the high-melting-point thermoplastic resin layer 3 is coextruded to form a laminated film having two layers, the surface of the high-melting-point thermoplastic resin layer of the laminated film and the other aluminum foil 4 are immediately after the co-extrusion. The surface of the second adhesive layer 6 formed by the surface is superposed, and is sandwiched and thermally laminated by being placed between a pair of heat rollers heated to 180 ° C to obtain a plan view rectangle as shown in FIG. Shaped exterior material 1.

The temporary sealing member 30 shown in Fig. 1(A) was produced by using the above-described exterior material 1 and by the means detailed in the foregoing. In other words, the inner layer 3 is folded twice as the inner side at the intermediate position in the longitudinal direction of the outer casing 1, and the outer front portion 21 of the outer casing is formed in a substantially rectangular shape, and the battery body portion having a rectangular shape in plan view is formed. 23 is disposed between the exterior material front portion 21 and the slightly rectangular outer material back surface portion 22. In the opposite side portion 32 opposed to the folded side 31 of the second folding, the outer surface front portion 21 and the outer material rear surface portion 22 are sandwiched between the positive electrode tab 11 and the negative electrode tab 12 by heat The sealing member or the like is joined to form the opposite side seal portion 35, and the first adjacent side portion 33 on the side adjacent to the folded side 31 is formed by heat sealing the outer front portion 21 and the outer member rear portion 22 The first adjacent side seal portion 36 is joined, and the second adjacent side portion 34 adjacent to the other side of the folded side 31 is formed by opening and sealing the outer front surface portion 21 and the outer surface rear portion 22 to form an opening. Opening portion 24, thereby creating The sealing member 30 is temporarily sealed (see Fig. 1(A)). The sealing width of the facing seal portion 35 and the first adjacent side seal portion 36 is set to 5 mm.

Then, the first adjacent side seal portion 36 of the temporary sealing member 30 is disposed on the lower side, and the opening portion 24 is in an upright state on the upper side, and the electrolyte injection nozzle 40 is used and inserted through the upper end opening portion to the battery. The main body portion 23 injects an electrolytic solution (see Fig. 1 (B)). The electrolyte solution is prepared by dissolving a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and dissolving it into a solution having a concentration of 1 mol/L (electrolyte) using lithium hexafluorophosphate (injection step). .

Next, the opening of the upper end of the gas chamber 41 in the temporary sealing element 30 is heat-sealed, and the gas chamber upper end sealing portion 37 is formed to form a sealed bag (see FIG. 1(C)). After that, the sealed bag (temporary sealing member) 30 is placed in the chemical conversion processing container 50 to be chemically processed, and the electrode material (positive electrode material and negative electrode material) is impregnated with the electrolytic solution (chemical conversion processing step) (see FIG. 2(A)). .

Then, while performing deaeration (vacuum degassing, etc.) inside the sealed bag (temporary sealing member) 30, the second adjacent side portion 34 of the sealed bag (temporary sealing member) 30 is heated by using the first heat sealing rod. The first sealing portion 27 is formed by sealing engagement (first sealing step). In the first sealing step, the heat sealing condition is 200 ° C × 0.2 MPa × 6 seconds. The first heat sealing rod is made of a fluororesin tape attached to the surface of a metal sealing rod.

After the first sealing step (after the completion of the degassing), the first sealing portion 27 is further heated and pressurized by the second heat sealing rod to form the second adjacent side sealing portion (plural return sealing portion) 27, and the exterior material is completed. Seal (second sealing step) (see Fig. 2(B)). In the second sealing step, the heat sealing condition is 200 ° C × 0.2 MPa × 6 seconds. 2nd The heat sealing rod is made of a fluororesin tape attached to the surface of a metal sealing rod.

Next, the portion (slightly upper half) corresponding to the gas chamber 41 in the sealed bag 30 is removed by trimming, and the laminated battery 10 shown in Fig. 2(C) is obtained.

<Comparative Example 1>

The sealing bag (temporary sealing member) 30 shown in Fig. 2(A) was obtained in the same manner as in the first embodiment until the chemical conversion treatment step. The degassing (vacuum degassing) inside the sealed bag (temporary sealing member) 30 is performed, and the second adjacent side portion 34 of the sealed bag (temporary sealing member) 30 is heat-sealed by using a heat sealing rod to form a first 2 abuts the side seal portion 27. In this sealing step, the heat sealing condition is 200 ° C × 0.2 MPa × 10 seconds. The heat sealing rod is made of a fluororesin tape attached to the surface of a metal sealing rod. Next, the portion corresponding to the gas chamber (slightly upper half) in the sealed bag was removed by trimming to obtain a laminated battery.

Each of the laminated batteries obtained above was evaluated based on the following evaluation method. The results are shown in Table 1.

<Sealing strength evaluation method>

In each of the laminated batteries, a test piece (width: 15 mm) was prepared from the second adjacent side seal portion 27, and the seal strength of the seal portion was measured at a tensile speed of 100 mm/min using a tensile tester manufactured by Shimadzu Corporation. (peel strength).

<Interlayer peeling (peeling) occurrence frequency evaluation method>

Ten laminated batteries of Example 1 were prepared, and ten laminated batteries of Comparative Example 1 were prepared. After each laminated battery was allowed to stand at room temperature for 7 days, it was investigated whether or not interlayer peeling (peeling) occurred in the second adjacent side seal portion of each laminated battery, and each of Example 1 and Comparative Example 1 produced a total of 10 samples (batteries). The number of samples (batteries) peeled off between the layers is shown in Table 1.

As is apparent from Table 1, the laminated battery of Example 1 obtained by the production method of the present invention can be shortened in steps and at the same time, sufficient sealing strength can be obtained without interlayer peeling (interlayer peeling). The frequency of occurrence is 0/10).

On the other hand, in the laminated battery of Comparative Example 1, sufficient sealing strength was obtained, and interlayer peeling did not occur (the frequency of occurrence of interlayer peeling was 0/10), but the sealing step required a long time and productivity. More inferior.

[The possibility of industrial use]

The method for producing a battery of the present invention can be suitably used as a method for producing a laminated secondary battery in which a lithium ion secondary battery or the like is laminated, but is not particularly limited to such use.

The present application claims priority to Japanese Patent Application No. 2014-263888, the entire disclosure of which is incorporated herein in

The terms and descriptions used herein are used to describe embodiments of the invention. Use, but the invention is not limited thereto. It is to be understood that any equivalents of the features disclosed and described herein are not to be construed as limited.

11‧‧‧ positive electrode tab

12‧‧‧Negative tabs

21‧‧‧ Front part of exterior material

23‧‧‧Battery body

24‧‧‧ openings

30‧‧‧ Temporary sealing element

31‧‧‧Folding edge (bending part)

32‧‧‧ opposite sides

33‧‧‧1st adjoining edge

34‧‧‧2nd adjoining edge

35‧‧‧ opposite edge seal

36‧‧‧1st adjacent edge seal

37‧‧‧Upper seal

40‧‧‧Electro injector injection nozzle

41‧‧‧ gas room

Claims (6)

A method for producing a battery, comprising the steps of: preparing a heat-resistant resin layer as an outer layer, a thermoplastic resin layer as an inner layer, and a metal foil layer disposed between the two layers; The exterior material is formed into a bag having a rectangular shape in plan view, and the battery body portion is disposed inside the bag body, and three of the four sides of the bag body in the vicinity of the periphery of the battery body portion are sealed, and At the same time, a temporary sealing member having an opening portion is formed in the remaining one side portion, and the temporary sealing member is disposed in a state in which the opening portion is opened upward toward the upper opening, and the tip end of the electrolyte injection nozzle is placed. Disposing the electrolyte solution in the battery body portion at a position directly above the opening portion or by inserting the opening portion; and a first sealing step of using a degassing device in the temporary sealing member after the injecting step a first sealing portion is formed by heat sealing the opening portion by using a first heat sealing rod while degassing, and a second sealing step after the completion of the degassing The first sealing portion is heated and pressurized using the second heat sealing rod. The method for producing a battery according to the first aspect of the invention, wherein the temperature of the first heat sealing rod when the heat sealing is performed in the first sealing step is set to a temperature equal to or higher than a melting point of the thermoplastic resin layer. The temperature of the second heat sealing rod when heat sealing is performed in the second sealing step is set to a temperature equal to or higher than the melting point of the thermoplastic resin layer. The method for manufacturing a battery according to the first aspect of the invention, wherein the temporary sealing The thermoplastic resin layer of the element includes a low-melting thermoplastic resin layer disposed on the inner surface side and a high-layer thermoplastic resin layer disposed on the metal foil layer side, and is formed in the first sealing step. The temperature of the first heat sealing rod at the time of heat sealing is set to a temperature equal to or higher than the melting point of the low melting point thermoplastic resin layer, and the temperature of the second heat sealing rod when heat sealing is performed in the second sealing step. It is a temperature above the melting point of the low melting point thermoplastic resin layer. The method for producing a battery according to any one of claims 1 to 3, wherein in the first sealing step and/or the second sealing step, a pair of heat sealing rods are used for the inner contact surface. Further, the heat sealing rod is formed of a curved shape that protrudes in a central portion of the heat sealing rod in the longitudinal direction or/and the lateral direction. The method for producing a battery according to any one of the first to third aspect of the invention, wherein in the first sealing step and/or the second sealing step, the inner contact surface is a one in which a porous sheet is disposed. For heat sealing rods. The method for producing a battery according to any one of claims 1 to 3, wherein one of the three sides sealed in the temporary sealing element is sealed by a bent portion, and the bent portion is sealed. The inner layer of the outer casing is disposed on the inner side and formed by folding twice.