JP5187733B2 - Manufacturing method of multilayer secondary battery - Google Patents

Description

  The present invention relates to a method for manufacturing a laminated secondary battery with a laminated exterior.

  A laminated secondary battery with a laminate sheath is made of a battery element in which a sheet-like positive electrode and a negative electrode formed by forming an active material layer on a current collector made of metal foil or the like are laminated with a separator interposed therebetween. Consists of a structure for storing and sealing.

  In recent years, with the widespread use of electric vehicles and hybrid vehicles, there is an increasing demand for stacked secondary batteries capable of high-rate discharge as well as increasing the capacity of secondary batteries. At the same time, the demand for low prices is increasing, and a high production yield is required.

  FIG. 2 is a cross-sectional view of a laminated secondary battery with a laminated exterior, FIG. 3 is a diagram showing an electrolyte solution injection process of a conventional laminated secondary battery, and FIG. 3 (a) is a front view, FIG. 3 (b) is a side view. In general, a laminated secondary battery with a laminate is made of a laminate composed of a positive electrode 1, a negative electrode 2, and a separator 3 as shown in FIG. 2, with the positive electrode terminal 5 and the negative electrode terminal 6 exposed. The foil is covered with a laminate coating material 4 that is resin-coated, and an electrolyte is injected and sealed. As shown in FIG. 3, the electrolyte solution is injected by sealing the periphery of the laminate with the laminate exterior material 4 except for the injection port 8 (the sealing portion is indicated by hatching), and then feeding the metering pump from the injection port 8. 9 or the like is used to inject the electrolyte solution 7 at a stroke, and the laminate is allowed to stand for a certain period of time under vacuum conditions to impregnate the laminate with the electrolyte solution. After the impregnation, the liquid inlet 8 is sealed in a vacuum state.

  However, wrinkles may occur in the electrode and the separator after electrolyte injection and sealing. Since the wrinkle creates a space between the separator and the electrode and does not adhere to it, even if a physical external force for stretching the wrinkle is applied later, it cannot be erased and the yield is deteriorated.

  The reason for the generation of wrinkles is that when the electrolyte is injected between the positive electrode, negative electrode, and separator of the laminate, if the electrolyte is injected all at once with a large gap between the positive electrode, negative electrode, and separator, The soaking variability increases, and in areas where soaking is slow, there is no path for the original air between the positive electrode, the negative electrode, and the separator to be surrounded by the electrolyte, and it cannot be discharged even in a vacuum. This is considered to be a wrinkle.

  In Patent Document 1, when a sheet-like separator having expansion anisotropy due to permeation of the electrolytic solution is used and the electrolytic solution is injected, the movement of the separator in the maximum expansion direction is not fixed, and the maximum expansion direction and the electrolytic solution are not fixed. A technique for infiltrating the electrolytic solution into the separator in a substantially parallel state with respect to the permeation direction of the liquid has been proposed.

JP 2005-222787 A

  The present invention has been made to solve such problems, and its technical problem is that in the method of manufacturing a laminated secondary battery in which an electrolyte is injected, the electrode and the separator are not wrinkled, and the electrical characteristics are It is an object of the present invention to provide a method for manufacturing a stacked secondary battery with a good yield.

The method for producing a laminated secondary battery according to the present invention includes a battery element in which a positive electrode connected to a positive electrode terminal and a negative electrode terminal connected to a negative electrode terminal are stacked via a separator, the positive electrode terminal and the negative electrode terminal. to expose the, housed in laminated outer member, a step of sealing with the exception of the injection port, the battery element is sandwiched between the housing and the laminated outer material in pressing plate, Zen'ekiryou the electrolyte from the pouring hole And a step of injecting at a liquid injection rate of 10 to 30% / hour, and a step of sealing the liquid injection port.

  According to the present invention, since the electrolytic solution permeates little by little in a state where the gap between the positive electrode, the negative electrode, and the separator is reduced, the penetration of the electrolytic solution becomes uniform. In addition, wrinkles do not occur before the electrolyte injection because there are few gas components between the positive electrode, negative electrode, and separator. Moreover, since it is not necessary to leave for a certain period of time under vacuum conditions, investment in expensive vacuum equipment can be reduced.

  Hereinafter, an embodiment of a method for manufacturing a laminated secondary battery of the present invention will be described more specifically with reference to the drawings. 1A and 1B are diagrams showing an electrolytic solution pouring step of the method for manufacturing a laminated secondary battery of the present invention, FIG. 1A being a perspective view seen from the front, and FIG. 1B being a side view. FIG. 2 is a cross-sectional view of a laminated secondary battery with a laminated exterior.

  As shown in FIG. 2, the laminated secondary battery is a laminate in which a laminate composed of a positive electrode 1, a negative electrode 2, and a separator 3 is resin-coated on an aluminum foil with the positive electrode terminal 5 and the negative electrode terminal 6 exposed. An exterior material 4 is used for the exterior, and an electrolyte is injected and sealed. The positive electrode 1 is obtained by forming a positive electrode active material layer on a positive electrode current collector made of, for example, a strip-shaped aluminum foil having a thickness of 20 μm. The positive electrode active material layer is a positive electrode active material made of, for example, lithium cobaltate, and a preparation prepared by adding a binder made of PVDF or the like and a conductive agent made of acetylene black or the like to form a slurry on the positive electrode current collector It is formed by coating on both sides of the film, drying, and rolling with a roll press. The negative electrode 2 is a negative electrode current collector, for example, a current collector made of a copper foil having a thickness of 10 μm, on which a negative electrode active material layer is formed. The negative electrode active material layer is prepared by, for example, applying a negative electrode active material made of graphite powder to a slurry with a binder made of PVDF or the like so as to form a slurry, drying it, and rolling it with a roll press It is formed by doing. Between the positive electrode 1 and the negative electrode 2, a battery element is produced by laminating a predetermined number of separators 3 as a separator 3 through a polyethylene nonwoven fabric or the like. Next, the positive electrode terminal 5 and the negative electrode terminal 6 are each joined to a current collector. The laminate outer packaging material 4 serving as an outer package is an aluminum laminate film having a three-layer structure of nylon / aluminum / polypropylene. In order to store battery elements, a storage portion by drawing is provided on the film so that the polypropylene side is concave. The battery element is housed in the battery element housing part of the film, the battery element is covered with the other film, the joints are overlapped, and the three sides are melted by thermal fusion, leaving a liquid injection port around the laminate exterior material 4. To wear.

  Next, as shown in FIG. 1, the battery element is covered with a laminate exterior material, and the surrounding three sides are fused (the fused portion is indicated by hatching). The liquid injection port 8 is arranged at the top, and the unsealed laminated secondary battery 12 is pressed and sandwiched by the flat pressing plate 11. In this state, the electrolyte solution 7 is injected little by little like an infusion using the needle syringe 10 from the injection port 8. After injecting the entire amount of the electrolytic solution, sealing is performed in a vacuum state.

  When the electrolyte solution is injected little by little like a drip into the battery element in which the pressure of 1 to 10 kPa is applied to both sides of the laminate exterior material by the pressing plate 11, the electrolyte solution soaks uniformly into the positive electrode, the negative electrode, and the separator. . By soaking uniformly, air is not unevenly distributed between the positive electrode, the negative electrode and the separator.

  In addition, in the case of this liquid injection method, there is not enough space for the electrolyte to enter because the battery element made of the laminated body is pressed, but since the liquid is injected while impregnating the laminated body, a device such as a needle syringe is used. However, it is preferable to inject the electrolytic solution over a period of 3 to several hours at an injection rate of 10 to 30% / hour of the total amount of liquid.

  Furthermore, when the electrolytic solution is injected in a vacuum apparatus, the impregnation rate of the electrolytic solution into the positive electrode, the negative electrode, and the separator is increased, and the time can be reduced.

  Hereinafter, the present invention will be specifically described based on examples.

  The positive electrode is a strip-shaped aluminum foil having a thickness of 20 μm prepared by adding a binder made of PVDF or the like and a conductive agent made of acetylene black to a positive electrode active material made of lithium cobalt oxide to form a slurry. It was formed by coating on both sides of a positive electrode current collector made of, drying, and rolling with a roll press. The negative electrode was prepared by applying a preparation prepared by making a negative electrode active material made of graphite powder into a slurry together with a binder made of PVDF on both sides of a current collector made of a copper foil having a thickness of 10 μm. And formed by rolling with a roll press. The positive electrode and the negative electrode are cut so that the dimensions are 120 mm × 200 mm, and the positive electrode and the negative electrode are opposed to each other through a separator made of polyethylene nonwoven fabric, so that the number of positive electrodes is 14 and the number of negative electrodes is 15 layers. In this way, a battery element was produced. Next, the positive electrode terminal and the negative electrode terminal are respectively joined to the current collector, the battery element is stored in a laminate outer material made of an aluminum laminate film having a three-layer structure of nylon / aluminum / polypropylene, and the periphery of the laminate outer material is injected. The three sides were fused by heat fusion leaving the mouth. The unsealed stacked secondary battery was sandwiched by applying pressure with a flat pressing plate, and an electrolytic solution was injected from the injection port using a needle syringe. After injecting the whole amount (15 g) of the electrolyte, it was sealed in a vacuum state. Table 1 shows the results of investigating the yield of good wrinkles by changing the pressure on the pressure plate and the injection rate of the electrolyte.

  When the pressing plate pressure was not applied, the yield was 20% regardless of the injection speed, whereas when the pressing plate pressure was applied, the yield was improved. In addition, what inject | poured the whole amount of electrolyte solution, and the electrolyte solution does not impregnate was described as electrolyte solution impregnation impossible.

The figure which shows the electrolyte solution pouring process of the manufacturing method of the laminated type secondary battery of this invention, FIG.1 (a) is the perspective view seen from the front, FIG.1 (b) is a side view. FIG. 3 is a cross-sectional view of a laminated secondary battery that is laminated. The figure which shows the electrolyte solution pouring process of the conventional multilayer secondary battery, FIG. 3 (a) is a front view, FIG.3 (b) is a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Laminate exterior material 5 Positive electrode terminal 6 Negative electrode terminal 7 Electrolyte 8 Injection port 9 Metering pump 10 Needle syringe 11 Holding plate 12 Unsealed laminated secondary battery

Claims (2)

A battery element in which a positive electrode connected to a positive electrode terminal and a negative electrode terminal connected to a negative electrode terminal are stacked via a separator, the positive electrode terminal and the negative electrode terminal are exposed, and stored in a laminate exterior material. The step of sealing except for the mouth, and the laminate outer material containing the battery element are sandwiched by a pressing plate, and the electrolyte is injected from the liquid inlet at an injection rate of 10 to 30% / hour of the total liquid volume. And a step of sealing the liquid injection port. A method for manufacturing a laminated secondary battery, comprising:   The method for manufacturing a laminated secondary battery according to claim 1, wherein the laminate packaging material containing the battery element is clamped at 1 to 10 kPa with a pressing plate.

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