JPH10275627A - Manufacture of power generating element for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optionally form the shapes of a positive electrode and a negative electrode and prevent short circuit between the positive electrode and the negative electrode by independently forming a positive electrode element and a negative electrode element before they are assembled as a power generating element. SOLUTION: Integrated positive electrode material and positive current collector are blanket with a mold formed in the specified shape to form a positive electrode element having the specified shape. Integrated negative electrode material and negative current collector are blanked with a mold formed in the specified shape to form a negative electrode element. A rotating blade and trimming with laser beam may be used to form the specified shape in place of blanking with the mold. The positive electrode element, a separator, and the negative electrode element are piled up, then they are formed in the specified shape to obtain a power generating element. By independently forming the positive electrode element and the negative electrode element, the power generating element capable of preventing the deposition of lithium on the negative electrode in charge can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generating element in a battery comprising a positive electrode mixture and a positive electrode current collector, a negative electrode mixture and a negative electrode current collector, and a diaphragm for electrically isolating them. And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, when a positive electrode mixture and a positive electrode current collector, a negative electrode mixture and a negative electrode current collector, and a diaphragm for electrically isolating these are laminated to form a power generating element, for example, a slurry is formed. Reel 1 in which the positive electrode mixture is applied on the positive electrode current collector using a coating machine or the like and wound into a reel shape, and the negative electrode mixture slurried on the negative electrode current collector using a coating machine or the like. And the reel 2 wound in the form of a reel, and the membrane reel 3 similarly wound in a reel shape, the reel 1 and the reel being arranged such that the positive electrode active material layer and the negative electrode active material layer face each other with the diaphragm interposed therebetween. 2. A method in which the reels 3 are arranged and spirally wound using a winding machine or the like to form a power generating element, or a positive electrode, a negative electrode, and a diaphragm extracted from the similarly arranged reels 1, 2 and 3 are taken out. Laminated using rolls, etc. Such methods have been known to be.

However, in the conventional method, for example,
In the case of the above-mentioned winding method, although it is an extremely preferable method for continuous production, if any of the reels 1, 2 and 3 has a winding deviation, a normal wound body cannot be obtained. Therefore, defects such as displacement of opposing electrodes and so-called bamboo shoot winding occurred, so that the yield of the process was remarkably reduced, and the raw material reel itself had to be treated as a defective product.

The above-mentioned lamination method is a method mainly used in a battery using a solid electrolyte as a diaphragm or a so-called laminated battery in which several flat power generating elements are laminated to form a battery. Although this method is preferable, in this method, since the positive electrode element, the diaphragm, and the negative electrode element are punched out after being laminated, the size of the facing electrode and the diaphragm therebetween are the same, and the electrode current collector is generated at the time of punching. The probability that the positive and negative electrode current collectors were short-circuited by the burr was high. In addition, chipping of the electrode material occurs due to the impact at the time of punching, and there is a risk that a short circuit may occur due to the chipped particles.

In addition, since the size of the positive electrode and that of the negative electrode are the same, for example, when a lithium ion battery is manufactured by this method, lithium ions dissociated from the positive electrode during charging precipitate as metallic lithium at the edge of the opposite negative electrode. In the case where the cyclability is lowered or lithium is deposited in a dendrite shape, a short circuit may occur by breaking through the diaphragm.

In order to avoid such a phenomenon, in the above-mentioned winding method, the size of the negative electrode is slightly larger than that of the positive electrode, and the size of the diaphragm is further increased. Further, when a solid electrolyte is used as a diaphragm, the current solid electrolyte itself has a thickness of about 100 μm, and even if burrs are generated, the probability of occurrence of the short circuit as described above is considerably low. However, in order to increase the capacity of the battery, the solid electrolyte itself tends to be thinner, and it is fully conceivable that such a short circuit will occur in the future.

[0007]

According to the present invention, the size and shape of the positive electrode element and the negative electrode element can be arbitrarily set, and not only the short circuit between the positive electrode and the negative electrode can be prevented, but also
In a lithium battery or the like, an object of the present invention is to provide a method for manufacturing a battery power generating element having a structure in which lithium is not deposited on a negative electrode element during charging.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and is as follows. (1) a positive electrode element comprising a positive electrode mixture and a positive electrode current collector, and
A negative electrode element composed of a negative electrode mixture and a negative electrode current collector is disposed so as to face each other, and a diaphragm for electrically isolating the electrode elements and maintaining ion conductivity is stacked between these electrode elements to generate power. In the production of the power generation element for batteries constituting the element,
The means for manufacturing the power generating element includes a first means for manufacturing the positive electrode element by molding the integrated positive electrode mixture and the positive electrode current collector into a predetermined shape, and an integrated negative electrode mixture and the negative electrode current collector. A second means for forming a negative electrode element by shaping the body into a predetermined shape; and a third means for forming a power generating element by forming the stacked positive electrode element, diaphragm and negative electrode element into a predetermined shape. A method for manufacturing a power generating element for a battery, wherein the first means and the second means are performed prior to the third means. (2) Fourth means for arranging the positive electrode element manufactured by the first means on a continuous sheet, and fifth means for arranging the negative electrode element manufactured by the second means on a continuous sheet 3. The method for manufacturing a power generating element for a battery according to the above 1, wherein the method is carried out prior to the third means. (3) a positive electrode element manufactured by the first means and a negative electrode element manufactured by the second means are arranged so as to face each other;
Further, a sixth means for superposing and integrating a diaphragm for electrically isolating the electrode elements and maintaining ion conductivity between the electrode elements is performed prior to the third means. 2. The method for producing a power generating element for a battery according to the above item 1, wherein (4) Including a continuous sheet used in the fourth means and a seventh means for peeling the continuous sheet used in the fifth means from the positive electrode element, the diaphragm and the negative electrode element integrated by the sixth means 4. The method for producing a power generating element for a battery according to the above item 1, 2 or 3, wherein

According to the manufacturing method of the present invention, the positive electrode element and the negative electrode element are independently molded before being molded as a power generating element, so that the shapes of the positive electrode and the negative electrode can be arbitrarily determined. Not only can short circuits be prevented,
In a lithium battery or the like, a power generating element having a structure in which lithium is not deposited on a negative electrode element during charging can be used.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and FIGS. Below, Figures 1 to 8
Each means for carrying out the embodiment of the present invention will be described with reference to specific examples, but the present invention is not limited by these exemplified means.

First, the case of manufacturing a positive electrode element in the case of a lithium ion secondary battery is exemplified by positive electrode active material particles such as lithium cobalt oxide, lithium nickel oxide and lithium manganate, and conductive fine particles such as graphite fine powder, acetylene black and carbon black. A positive electrode material slurry is prepared by uniformly dispersing a auxiliaries, a binder resin such as polyvinylidene fluoride, etc., and a solvent such as N-methylpyrrolidone using a planetary mixer, extruding this from a die and simultaneously using aluminum foil as a positive electrode current collector. After passing through the front of the die, the extruded slurry is transferred onto the positive electrode current collector, and if necessary, after adjusting the coating thickness and the coating amount using a doctor blade, the solvent is volatilized using hot air, The positive electrode material and the positive electrode current collector are integrated.

At this time, as a dispersing means, a dissolver, a bead mill, a kneader, a Banbury mixer, a homogenizer, a Henschel mixer or the like can be used in addition to the planetary mixer. Also, when transferring the slurry of the positive electrode material onto the current collector, in addition to the method of extruding the slurry of the positive electrode material from the die, a coating machine such as a pipe doctor coater, a reverse roll coater, and a blade coater can be used. . Further, as a means for volatilizing the solvent, not only hot air but also means such as far infrared rays can be used.

Next, in the case of manufacturing a negative electrode element, the case of a lithium ion secondary battery is similarly exemplified. Graphite particles, finely divided carbon fibers, negative electrode active material particles such as coke particles, graphite particles, acetylene black, A slurry of a negative electrode mixture is prepared by uniformly dispersing a conductive auxiliary such as carbon black, a binder resin such as polyvinylidene fluoride and styrene butadiene rubber, a solvent such as N-methylpyrrolidone, and water using a planetary mixer. The copper foil is passed through the front of the die as a negative electrode current collector at the same time as extruding from the die, the slurry of the extruded negative electrode mixture is transferred onto the negative electrode current collector, and if necessary, the coating thickness using a doctor blade Is adjusted, the solvent is volatilized by using hot air to integrate the negative electrode mixture and the negative electrode current collector.

At this time, as a dispersing means, besides the planetary mixer, a dissolver, a bead mill, a kneader, a Banbury mixer, a homogenizer, a Henschel mixer and the like can be used. Also, when transferring the slurry of the negative electrode mixture onto the current collector, in addition to the method of extruding the slurry of the negative electrode mixture from the die, a coating machine such as a pipe doctor coater, a reverse roll coater, or a blade coater may be used. It is possible. Also, as a means for volatilizing the solvent, not only hot air but also means such as far infrared rays can be used.

The first means in the present invention is a method of manufacturing a positive electrode element by molding an integrated positive electrode material and a positive electrode current collector into a predetermined shape as shown in FIGS. Here, the integrated positive electrode active material and the positive electrode current collector can be punched into a predetermined shape by using a mold formed in a predetermined shape. As the first means, it is possible to obtain a positive electrode element by forming into a predetermined shape using not only punching but also trimming with a rotary blade and trimming with a laser beam. For example, a square positive electrode element having a side of 50 mm can be obtained independently.

The second means in the present invention is a method of manufacturing a negative electrode element by molding an integrated negative electrode mixture and a negative electrode current collector into a predetermined shape as shown in FIGS. Similarly to the first means, the integrated negative electrode mixture and the negative electrode current collector can be punched into a predetermined shape by using a mold formed in a predetermined shape. As the second means, it is possible to obtain a negative electrode element by forming into a predetermined shape using not only punching but also trimming with a rotary blade and trimming with a laser beam.
For example, when a diaphragm such as a solid electrolyte is used, the necessity is thought to be low.However, in order to avoid the conventional problem of electrodeposition of lithium, the cathode element obtained by the first means was used. As a larger element, a negative electrode element having a side of 55 mm can be obtained independently.

The third means in the present invention is a means for obtaining a power generating element by forming the stacked positive electrode element, diaphragm and negative electrode element into a predetermined shape as shown in FIGS. 1 and 4.
Here, a power generating element having a desired shape can be obtained in the same manner as the means described in the description of the first means and the second means. For example, a square power generating element 60 mm on a side can be obtained to prevent a short circuit between the positive electrode and the negative electrode.

According to the manufacturing method of the present invention, since the first means and the second means are performed prior to the third means, the obtained power generating element is a negative electrode element. The size protrudes 2.5 mm larger than the positive electrode, and not only does not have a structure in which lithium is deposited on the negative electrode element during charging, but the diaphragm also protrudes 2.5 mm larger than the positive electrode element. And a power generating element having a structure in which a short circuit between the negative electrode element and the negative electrode element does not occur.

Further, embodiments of the fourth means, the fifth means, the sixth means, and the seventh means for improving the production efficiency while utilizing the effects of the present invention will be described below. The fourth means is a method of arranging a positive electrode element formed into a predetermined shape by the first means on a continuous sheet as shown in FIGS. In carrying out this, for example, the positive electrode element formed by the first means can be arranged on a continuous film of polyester having a surface coated with an adhesive by using a vacuum suction means. At this time, it is efficient to equalize the arrangement pitch of the positive electrode element on the continuous film in order to accurately align the negative electrode element with the opposite one, so that sprocket holes are formed on both sides of the continuous film. Preferably, the feeding of the continuous film and the operation of the vacuum suction device are synchronized.

As a method of equalizing the arrangement pitch, besides using sprocket holes, a register mark is printed in advance on a continuous film, and the position of the register mark is read by an optical means or the like, and the mark is synchronized with the vacuum suction means. Method, using a thickness sensor, detect the position of the positive electrode element arranged in advance, calculate the next position to be arranged from the feed speed of the continuous film, a method such as applying feedback to the vacuum suction means It is also possible to use. As the continuous film, besides polyester, a film of polyethylene, vinyl chloride, polypropylene, polyimide, aramid or the like can be used, but a polyester film is preferable in terms of dimensional accuracy, rigidity, and price. In addition, it is also possible to mechanically pick up other than the vacuum suction means, but vacuum suction is preferable to avoid damaging the electrodes.

The fifth means is a method of arranging a negative electrode element formed in a predetermined shape on a continuous sheet, as shown in FIGS. 1 and 6, similarly to the fourth means. In carrying out this, the negative electrode element formed by the second means in the same manner as the fourth means can be placed on a continuous film of polyester coated with an adhesive on the surface by using a vacuum suction means. . At this time, it is efficient to equalize the arrangement pitch of the negative electrode elements on the continuous film in order to accurately align with the opposed positive electrode elements, so that sprocket holes are formed on both sides of the continuous film. ,
It is preferable to synchronize the feeding of the continuous film with the operation of the vacuum suction device.

As a method for equalizing the arrangement pitch, besides using sprocket holes, a register mark is printed in advance on a continuous film, and the position of the register mark is read by an optical means or the like, and synchronized with the vacuum suction means. Method to use, using a thickness sensor, detect the position of the previously arranged negative electrode element, calculate the next position to be arranged from the feed speed of the continuous film, a method such as applying feedback to the vacuum suction means It is also possible to use.

As the continuous film, besides polyester, a film of polyethylene, vinyl chloride, propylene, polyimide, aramid or the like can be used, but a polyester film is preferred in view of dimensional accuracy, rigidity and cost. . In addition, it is also possible to mechanically pick up other than the vacuum suction means, but vacuum suction is preferable to avoid damaging the electrodes.

In the sixth means, as shown in FIGS. 1 and 7, the positive electrode element formed by the first means and the negative electrode element formed by the second means are arranged so as to face each other. It is a method of electrically isolating the electrode elements between these electrode elements and stacking and integrating a membrane retaining ion conductivity.For example, as the membrane, propylene carbonate and ethylene carbonate are used in advance. A polyvinylidene fluoride sheet impregnated with an electrolytic solution in which 1 mol of lithium borofluoride is dissolved per liter of the same volume mixed liquid is extracted from a reel, and is simultaneously placed on a continuous film by the fourth means and the fifth means. The positive electrode element and the negative electrode element are pressure-bonded through a calender roll to obtain an integrated product of the positive electrode element, the diaphragm, and the negative electrode element.

At this time, when the positive electrode element, the diaphragm, and the negative electrode element are integrated only by pressure, the pressing force may be insufficient depending on the electrode material composition and the resin composition of the diaphragm. A way to increase power is also possible. For example, when a diaphragm not impregnated with the electrolytic solution is used, or when the binder used for the electrode and the resin constituting the diaphragm have low compatibility, heating is necessary.

As shown in FIGS. 1 and 8, the seventh means comprises a continuous sheet used in the fourth means and a fifth sheet from the positive electrode element, the diaphragm and the negative electrode element integrated by the sixth means. This is a means for peeling the continuous sheet used in the means. From the outlet of the sixth means, as shown in FIG. 1, the continuous sheet used in the fourth means and the continuous sheet used in the fifth means are integrated by the sixth means while being independently wound. The continuous sheet can be peeled off by sending the positive electrode element, the diaphragm, and the negative electrode element. As described in the description of the sixth means, when the positive electrode element, the diaphragm, and the negative electrode element are integrated by the sixth means, either one or both between the positive electrode element and the diaphragm, or between the negative electrode element and the diaphragm. If the adhesion is low, peeling occurs between the positive electrode element and the diaphragm or between the negative electrode element and the diaphragm at this time, making it impossible to obtain a power generation element. Is preferably stronger than the adhesiveness between the positive electrode element and the continuous sheet and between the negative electrode element and the continuous sheet, and the direction in which the continuous sheet is peeled off, that is, the direction in which the continuous sheet advances in the eighth means in FIG. It is necessary to appropriately adjust the angle between the traveling directions of the elements according to the adhesive strength.

In FIG. 1, the seventh means is implemented prior to the third means. However, in actual assembly of the battery, after the third means is implemented, these power generating elements are stacked several times. Since the next step of assembling into an actual battery or supplying an electrolyte occurs, the continuous sheet used in the fourth means and the fifth means is used for the positive electrode element and the negative electrode element until the next step. When used as a protective film, the third means can be performed prior to the seventh means. However, when the third means is performed prior to the seventh means, it is not preferable from the viewpoint of continuous productivity, and the seventh means is preferably performed prior to the third means.

[0028]

According to the manufacturing method of the present invention, the positive electrode element and the negative electrode element are independently molded before being molded as a power generating element, so that the shapes of the positive electrode and the negative electrode can be arbitrarily determined. Not only the short circuit of the negative electrode can be prevented, but also in the case of a lithium battery or the like, a power generating element having a structure in which lithium is not deposited on the negative electrode element during charging can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing an example of steps of a manufacturing method of the present invention.

FIG. 2 is a conceptual diagram of an example of a first means in the present invention.

FIG. 3 is a conceptual diagram of an example of a second means in the present invention.

FIG. 4 is a conceptual diagram of an example of a third means according to the present invention.

FIG. 5 is a conceptual diagram of an example of a fourth means in the present invention.

FIG. 6 is a conceptual diagram of an example of a fifth means in the present invention.

FIG. 7 is a conceptual diagram of an example of a sixth means in the present invention.

FIG. 8 is a conceptual diagram of an example of a seventh means in the present invention.

Claims (4)

[Claims] 1. A positive electrode element comprising a positive electrode mixture and a positive electrode current collector and a negative electrode element comprising a negative electrode mixture and a negative electrode current collector are arranged so as to face each other, and further, the electrode is provided between these electrode elements. In the production of a power generation element for a battery, which constitutes a power generation element by superposing a diaphragm for electrically isolating elements and maintaining ion conductivity, the means for manufacturing the power generation element comprises an integrated positive electrode mixture and a positive electrode. A first means for manufacturing the positive electrode element by molding the current collector into a predetermined shape, and a second means for manufacturing the negative electrode element by molding the integrated negative electrode mixture and the negative electrode current collector into a predetermined shape A method for producing a power generating element for a battery, comprising: forming a power generating element by forming a stacked positive electrode element, a diaphragm, and a negative electrode element into a predetermined shape, wherein the first means and the second means are provided. Is performed prior to the third means. Element manufacturing method. 2. A fourth means for arranging the positive electrode element produced by the first means on a continuous sheet, and a fifth means for arranging the negative electrode element produced by the second means on the continuous sheet. 2. The method according to claim 1, wherein the means is performed prior to the third means. 3. A positive electrode element manufactured by the first means and a negative electrode element manufactured by the second means are arranged so as to face each other, and between these electrode elements, an electrical connection is made between the electrode elements. The method for manufacturing a power generating element for a battery according to claim 1, wherein the sixth means for stacking and integrating the membranes for isolating and maintaining ion conductivity is performed prior to the third means. . 4. A seventh means for separating the continuous sheet used by the fourth means and the continuous sheet used by the fifth means from the positive electrode element, the diaphragm and the negative electrode element integrated by the sixth means. The method for manufacturing a power generating element for a battery according to claim 1, 2 or 3, comprising: