JP4403698B2 - Winding battery manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a battery, and more particularly to a winding process of the electrode group.
[0002]
[Prior art]
In recent years, electronic devices have become rapidly portable and cordless. Among them, power supplies for laptop computers, mobile phones, and AV equipment, which are particularly popular, include conventional aqueous secondary batteries (nickel cadmium storage batteries, nickel metal hydride storage batteries) and smaller, lighter, higher energy density lithium ions. Small secondary batteries such as secondary batteries are mainly used.
[0003]
As the portability and diversification of devices increase, further improvements in reliability are necessary for small secondary batteries. There are some problems, but among them, there is a problem that the separator cannot keep the positive electrode and the negative electrode separated from each other due to abnormal impact on the battery or abnormal heating, and Joule heat is generated at the short-circuit location.
[0004]
The separator is required to have a function of maintaining the separation between the positive electrode and the negative electrode with sufficient mechanical and thermal strength. For example, a separator used in a lithium ion secondary battery is generally a microporous film made of polyethylene or polypropylene, and has a problem that it is easily and significantly contracted by heating unless the film is tensioned. .
[0005]
Conventionally, in order to prevent an internal short circuit in a battery, a method of welding a separator and wrapping an electrode plate has been proposed. (For example, see Patent Document 1)
In addition, a configuration in which the upper and lower end faces of the electrode group after winding are thermally welded has been proposed. (For example, see Patent Document 2)
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 63-239766 [Patent Document 2]
Japanese Patent Laid-Open No. 1-122574 [0007]
[Problems to be solved by the invention]
However, the method of welding the separator and wrapping the electrode plate may be a so-called laminated battery in which the electrode plate is laminated on a flat plate, but in the wound type battery mainly used at present, There was a problem that the separator was wrinkled during rotation, making it difficult to manufacture.
[0008]
In addition, the structure where the upper and lower end faces of the electrode group after winding are heat-welded continuously welds the separators on the end faces in layers, so both the effect of preventing internal short circuit due to welding and the impregnation of the electrolyte are compatible. It was difficult to do.
[0009]
An object of the present invention is to solve the above-described problems, and to provide a wound battery that is easy to wind and has a reliable prevention of short circuit and excellent electrolyte impregnation.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a winding type electrode group in which the two ends of the separators existing on the front and back of either the positive electrode or the negative electrode are wound while being thermally welded. did.
[0011]
Thereby, even if it is a wound type electrode group, a separator can be welded without wrinkles.
[0012]
Moreover, it is preferable to perform heat welding in a perforated pattern at regular intervals.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is a method for manufacturing a wound battery in which an electrode group is formed by winding a positive electrode and a negative electrode through a separator, wherein the winding step of the electrode group includes a positive electrode or a negative electrode It is characterized by winding while both ends of the separators existing on the front and back of either one of the electrode plates are thermally welded, and the battery is subjected to abnormal external shock, load or abnormal temperature The positive electrode and the negative electrode do not easily contact each other.
[0014]
In addition, by winding while heat-welding, even a wound electrode group can be welded without wrinkling the separator, and can be easily inserted into a battery can, and the capacity of the battery can be increased. There is also an effect. Since welding is performed between only two electrodes on the front and back of one electrode plate, a portion that is not welded even if all of them are welded may be provided.
[0015]
According to a second aspect of the present invention, in the method for manufacturing a wound battery according to the first aspect, the thermal welding is performed in a perforated manner at regular intervals. The separator shrinkage force at high temperature is evenly distributed, and the mechanical influence of the separator itself may be small. This perforated interval can be appropriately selected depending on the separator and the electrolytic solution used in consideration of safety and the impregnation property of the electrolytic solution.
[0016]
【Example】
Hereinafter, examples will be described in detail with reference to FIGS. 1 and 2 by taking a lithium ion secondary battery as an example.
<Example battery A>
(Preparation of positive electrode)
A positive electrode mixture paste prepared by kneading and dispersing a predetermined amount of a positive electrode active material made of LiCoO ₂ , a conductive material made of acetylene black (AB), a binder made of PVdF, and a solvent made of N-methyl-2-pyrrolidone (NMP). Was applied to a current collector made of aluminum (Al) foil having a thickness of 15 μm. Then, drying and rolling were performed, and it cut | disconnected to the predetermined dimension, and produced the positive electrode plate for lithium ion secondary batteries. The width of the positive electrode is 54 mm.
[0017]
(Preparation of negative electrode)
Next, a negative electrode paste was prepared using graphite, a binder, a thickener, and pure water, and applied to a current collector made of a copper (Cu) foil having a thickness of 12 μm. Then, drying and rolling were performed, and it cut | disconnected to the predetermined dimension, and produced the negative electrode plate for lithium ion secondary batteries. The width of the negative electrode is 56 mm.
[0018]
(Production of electrode group)
Next, an electrode group was configured as shown in FIG. 1 using a positive electrode plate, a negative electrode plate, and a separator made of a microporous polyethylene resin having a thickness of 20 μm and a width of 60 mm. A positive electrode lead 5 is welded to the positive electrode 1, and a negative electrode lead 6 is welded to the negative electrode 2. First, the negative electrode 2, the separator 3, the positive electrode 1, and the separator 3 were laminated in order and wound. In the winding process, the ends of the separators 3 existing on the front and back of the positive electrode 1 were thermally welded at 10 mm intervals so as to wrap the positive electrode 1. 4 is a separator heat welding part. The obtained electrode group was designated as Example electrode group A.
[0019]
After the obtained example electrode group A was housed in a cylindrical metal case, the positive electrode lead 5 was welded so as to be electrically connected to the sealing plate, and the negative electrode lead 6 was electrically connected to the metal case. Thereafter, an electrolytic solution was poured and sealed with a sealing plate. After sealing, the battery was allowed to stand for a predetermined time and further charged with a predetermined amount of electricity to produce a lithium ion secondary battery. This battery had a diameter of 18 mm, a total height of 65 mm, and a battery capacity of 1800 mAh. <Example battery B>
As shown in FIG. 2, the same positive electrode 1, negative electrode 2, and separator 3 as those of Example Battery A were used, and the separator 3, the negative electrode 2, the separator 3, and the positive electrode 1 were sequentially laminated and wound. In the winding process, the ends of the separators 3 existing on the front and back sides of the negative electrode 2 were thermally welded at intervals of 10 mm to wrap the negative electrode 2. The obtained electrode group was named Example electrode group B.
[0020]
Thereafter, Example Battery B was produced in the same manner as Example Battery A.
<Comparative battery A>
An electrode group in which the positive electrode plate and the negative electrode plate were wound through a separator made of a microporous polyethylene resin having a thickness of 20 μm and a width of 60 mm was used as Comparative Example Electrode Group A. In Comparative Example Electrode Group A, as in Example Electrode Group A or B, the electrode group end separator is not thermally welded. After this was inserted into a metal case, the battery was completed in the same manner as in the example battery, and a comparative example battery A was obtained.
<Battery safety evaluation>
(Heat resistance test)
The battery was charged to 4.2 V with a current of 1.8 A, and thereafter, the charging current value was attenuated so that the battery voltage was maintained at 4.2 V, and the battery was charged until the charging current value became 0.1 A.
[0021]
The charged example batteries A and B and comparative battery A were charged into a heating furnace, and the heating furnace was heated from 20 ° C. to 150 ° C. at a rate of 5 ° C./min. After the heating furnace reached 150 ° C., the furnace temperature was maintained at 150 ° C.
[0022]
In addition, in order to observe the behavior under test in the battery, a thermocouple was attached to the surface for battery temperature measurement.
[0023]
About the safety | security of a heat test, it was set as 3 hours after reaching | attaining 150 degreeC.
<Evaluation results>
In Comparative Example Battery 1, the temperature suddenly increased about 30 minutes after the battery temperature reached 150 ° C.
[0024]
On the other hand, in Example batteries A and B according to the present invention, no temperature increase was observed after reaching 150 ° C., and there was no abnormality during the test. In the comparative battery, the separator contracted in the width direction during the temperature rising process, so the positive electrode and the negative electrode were locally short-circuited, and it was estimated that the thermal runaway temperature of the battery was reached by the short-circuit Joule heat. On the other hand, in the example battery, the separators were thermally welded so as to sandwich the electrode, so it was estimated that there was no local short circuit due to the separator contraction.
[0025]
In the practice of the present invention, the effect was shown with a cylindrical battery, but the same effect can be obtained even with an electrode group wound in an elliptical shape or a flat shape.
[0026]
【The invention's effect】
According to the present invention, a highly safe wound battery can be provided by adopting a structure in which the positive electrode and the negative electrode are not easily contacted even when an external impact, load, or abnormal temperature is applied to the battery.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an example electrode group A of the present invention. FIG. 2 is a schematic diagram of an example electrode group B of the present invention.
DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Separator heat welding part 5 Positive electrode lead 6 Negative electrode lead

Claims (3)

In a method for manufacturing a wound battery in which a positive electrode and a negative electrode are wound through a separator to constitute an electrode group,
In the winding process of the electrode group, first, a negative electrode, a separator, a positive electrode, and a separator are sequentially stacked and wound, and in the winding process, end portions of the separators existing on the front and back of the positive electrode are thermally welded. A method for manufacturing a wound battery , wherein the positive electrode is wrapped . In a method for manufacturing a wound battery in which a positive electrode and a negative electrode are wound through a separator to constitute an electrode group,
In the winding process of the electrode group, first, a separator, a negative electrode, a separator, and a positive electrode are sequentially laminated and wound, and in the winding process, the end portions of the separators existing on the front and back of the negative electrode are thermally welded. A method of manufacturing a wound battery , wherein the negative electrode is wrapped . Wound type method for producing a battery according to claim 1 or 2, wherein the heat welding and performing a perforated line at regular intervals.

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