JP2003297430A - Method of manufacturing secondary battery and device for manufacturing secondary battery electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize oxidation of a lithium foil and to laminate the lithium foil on an electrode with good adhesion. <P>SOLUTION: A method of manufacturing a secondary battery accommodating positive and negative electrodes 2, 3 and an electrolyte in a case comprises steps of: providing a lithium mass between rolls for rolling the lithium mass to produce a lithium foil, superposing the lithium foil 21 on the electrode 2 and pressing the electrode and the lithium foil to integrate them; and cutting the continuous electrode by every predetermined length. Furthermore, at least two steps among electrode assembling steps are carried out, the electrode assembling comprising steps of: cutting the electrode by crossing a blade having a plane along a contour of the cut portion without the cutting line with the continuous electrode, the electrode cutting step being performed alternately with the cutting step; a arranging the positive electrode and the negative electrode alternately; disposing a separator 25 having a continuative elongated sheet shape along either side of either electrode and the other side of the other electrode; and superposing both electrodes via the separator. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a secondary battery such as a lithium secondary battery, and a manufacturing apparatus for electrodes used in the secondary battery.

[0002]

2. Description of the Related Art In recent years, secondary batteries have been used in various fields. For example, if it is small, it is used as a power source for electronic devices such as mobile phones and video cameras. Further, if it is large, it is used as a power source for electric vehicles or a power storage device for home use. Further, in place of the lead secondary battery and the nickel-cadmium secondary battery that have been conventionally used, a lighter and more compact lithium secondary battery is becoming popular.

FIG. 6 shows a conventional example of the lithium secondary battery. This lithium secondary battery 1 is of a so-called prismatic type, and comprises a plurality of (positive electrode) electrodes 2, a (negative electrode) electrode 3, and a separator 4 arranged between these electrodes 2 and 3 made of stainless steel. The battery case 5 is made of, for example, and is filled with a non-aqueous electrolyte solution. The opening of the battery case 5 is closed by a sealing body 6.

The positive electrode 2 and the negative electrode 3 are alternately stacked with a separator 4 interposed therebetween. A positive electrode tab 12a is formed at one end of the positive electrode 2 and the positive electrode tabs 12a are connected to each other by a positive electrode lead 12b. A positive electrode terminal 7 is attached to the positive electrode lead 12b, and a tip of the positive electrode terminal 7 penetrates the sealing body 6 and projects to the outside. A negative electrode tab 13a is formed at one end of the negative electrode 3, and the negative electrode tabs 13a are connected to each other by a negative electrode lead 13b. A negative electrode terminal 8 is attached to the negative electrode lead 13b, and a tip of the negative electrode terminal 8 penetrates the sealing body 6 and projects to the outside.

The positive electrode 2 is formed by laminating a positive electrode layer of graphite or the like on the surface of a positive electrode current collector made of, for example, an Al plate (or foil), and further forming L on the surface of the positive electrode layer.
It has a configuration in which a Li foil as an i (lithium) ion supply source is covered.

[0006]

By the way, the above-mentioned Li
Has a large surface area by being formed in a foil shape, and it takes some time before being laminated on the electrode after being formed in a foil shape, and therefore oxidation of the surface is unavoidable. Depending on the degree of oxidation, it may not be able to function as a Li source.

Therefore, it is possible to cover the surface of the manufactured Li foil with an antioxidant or the like, but the presence of this antioxidant may adversely affect the performance of the secondary battery.

The present invention has been made in view of the above circumstances, and an object of the present invention is to laminate Li foil with good adhesion while preventing oxidation of Li foil as much as possible, and to manufacture the electrode. The purpose is to reduce as much as possible the generation of chips that may cause defective batteries.

[0009]

In order to achieve the above object, the manufacturing method of the present invention is a method for manufacturing a secondary battery in which a positive electrode and a negative electrode are housed together with an electrolytic solution in a battery case. A step of continuously producing in a predetermined direction, a step of supplying a lithium ingot between rolls and rolling into a foil shape, and a lithium foil sent out from between the rolls is overlaid on the continuously produced electrode. The process of matching,
And pressing the stacked electrodes and the lithium foil in the thickness direction to integrate them. Further, in a method for manufacturing a secondary battery in which a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, a step of continuously manufacturing the electrodes in a predetermined direction, and a step of continuously manufacturing the electrodes for a predetermined length And a punching step of cutting by cutting a blade having a planar shape along the contour of the electrode excluding a cutting line by the cutting step with the continuous electrode. It is characterized in that it is carried out alternately with the cutting step. Further, in a method for manufacturing a secondary battery in which a positive electrode and a negative electrode are housed in a battery case together with an electrolyte, a step of manufacturing the electrode and a step of alternately arranging the positive electrode and the negative electrode A step of arranging a continuous separator in a long sheet shape along one side surface of one electrode and the other side surface of the other electrode, and interposing the positive electrode and the negative electrode between the separators. It is characterized by comprising a step of allowing them to be superposed. Further, in each of the above-mentioned manufacturing methods, at least two steps of a lithium stacking step of manufacturing an electrode on which a lithium foil is stacked, an electrode cutting step, and an electrode assembling step are performed. Further, the electrode device of the present invention is a secondary battery manufacturing apparatus in which the positive electrode and the negative electrode are housed in a battery case together with an electrolytic solution, and a rolling unit that supplies a lithium ingot between rolls and rolls it into a foil, And a pressing means for pressing the lithium foil fed from between the rolls of the rolling means onto the continuously manufactured electrode, wherein the rolling means is a continuously fed electrode. Each of the pressing means is provided on both sides of the electrode, and the pressing means is composed of a pair of rollers for compressing the electrode and the lithium foil fed to both sides thereof from both sides.
Further, the roller is characterized in that it has irregularities on its outer peripheral surface. Also, an elastically deformable layer is provided on the surface of the roller.

FIG. 1 shows a manufacturing method according to an embodiment of the present invention. (A) is a laminating step, in which the lithium foil 21 is supplied from both sides to the electrode (the positive electrode 2 in the illustrated example) that is continuously fed out, and these are fed to the pair of pressure bonding rollers 2
It is compressed by 2 and pressed together. B is a cutting step, in which the electrode 2 on which the lithium foil 21 is laminated is moved in the longitudinal direction (rightward in FIG. 1) by the laminating step of (a), and the electrode 2 is cut by a cutting means 23 such as a die cutter.
A blade having a predetermined shape is crossed in the thickness direction to cut it into a predetermined contour, and the electrode 2 is further cut by a cutter 24 along a cutting line in the width direction (the paper surface direction of FIG. 1) and separated one by one. The electrode 2 is obtained. The same applies to the negative electrode. C is an electrode assembling step, in which the positive electrode 2 and the negative electrode 3 obtained in the above step B are separated by, for example, 5
As shown in FIG. 6, by interposing the separators 25 while interposing them in pairs and alternately folding them in a zigzag shape.
Similar to the conventional example, an electrode assembly can be obtained in which the positive electrode 2 and the negative electrode 3 are superposed with the separator 25 interposed therebetween. The second is a battery assembling step, in which the positive electrode 2 is superposed by the above step c.
By accommodating the negative electrode 3 and the negative electrode 3 in the battery case together with the electrolytic solution as in the conventional example, attaching a predetermined terminal and connecting the terminal and the electrode by a lead conductor,
The lithium secondary battery is completed.

The apparatus used in the above-mentioned laminating step is shown in FIG.
The configuration is shown in. Reference numeral 30 denotes a lithium supply unit, and the lithium supply unit 30 stores lithium 31 as a metal block and sends it out downward. A pair of delivery rolls 32 are provided below the lithium supply unit 30 so that the lithium 31 can be pulled out with a predetermined thickness.
Below the delivery roll 32, a pair of rolling rolls 33 are provided, and the lithium foil 21 having a predetermined thickness is formed by these rolling rolls 33.

An electrode (positive electrode 2 in the illustrated example) moves downward between the lithium foil supply systems on both sides in FIG. 2, and the positive electrode 2 is made of a general metal such as aluminum. The positive electrode current collector 2a is composed of a positive electrode current collector 2a and a positive electrode layer 2b made of powder such as graphite is provided on the surface of the positive electrode collector 2a. The positive electrode 2 is fed together with a lithium foil 21 supplied from both sides between a pair of pressure-bonding rolls 22 and is compressed in the thickness direction so as to be pressure-bonded integrally.

The surface of the pressure-bonding roll 22 is made of a soft material such as resin or rubber, and absorbs variations in the thickness of the lithium foil 21 and the electrode 2. The surface shape of the pressure-bonding roll 22 is not limited to a flat shape, and as shown in FIG. 3, a plurality of convex portions 34 are provided at predetermined intervals in the circumferential direction, or fine irregularities are formed by knurling or the like. May be provided. As described above, the unevenness is provided on the surface of the pressure-bonding roll 22, so that the lithium foil 21 can be pressure-bonded to the electrode 2 (or 3) with a partially large pressure-bonding force. Further, since the crimping portion is plastically deformed in an uneven shape, it is possible to reliably prevent the lithium foil 21 and the electrode 2 (or 3) from being displaced in the surface direction.

In the supply of the lithium foil, since the surface area of lithium is increased by rolling and the lithium foil is easily oxidized, the rolled lithium is rolled by bringing the rolling roll 33 and the pressure contact roll 22 as close as possible to each other. It is desirable to keep the foil travel path as short as possible. That is, by laminating the lithium foil immediately after rolling, the oxidation can be suppressed as much as possible.

FIG. 4 shows a cutting blade 40 used in the above cutting step (b). The blade 40 has a planar shape corresponding to the contour of the electrode 2 or 3 as shown by the solid line and the chain line in FIG. Note that the blade 40 actually exists in the range shown by the solid line in FIG. 4, and by cutting this range, cutting into a shape in which a plurality of electrodes 2 or 3 are connected is performed, and then the cutter 24 By cutting the portion of the chain line C linearly with, a planar shape corresponding to the contour of the electrode 2 or 3 is formed. That is, by cutting the continuous electrode with the cutting means 23 and the cutter 24, as shown in FIG. 5, the positive electrode layer 2b is laminated on the positive electrode current collector 2a having the positive electrode tab 12a in plan view, Furthermore, lithium foil 2 is used as part of it.
The positive electrode 2 (or the negative electrode 3) in which 1 is laminated is formed.

Using the positive electrode 2 and the negative electrode 3 formed as described above, the positive electrode tab 12a and the negative electrode tab 13a are set in the directions opposite to each other in the electrode assembling process of the above C, and a zigzag shape is formed between them. By alternately stacking the separators 25 with the separators 25 interposed therebetween, it is possible to obtain an electrode assembly in which the positive electrode 2 and the negative electrode 3 are folded in a zigzag shape and are stacked with the separators 25 interposed therebetween. By thus folding the separator 25 in a zigzag manner and interposing the separator 25 therebetween, even if there is a deviation between the positive electrode 2 and the negative electrode 3, the separator 25 can be interposed between them. it can. Then, the electrode assembly thus formed is housed in a battery case together with an electrolytic solution, and a terminal is attached and wired to the terminal, thereby completing a lithium secondary battery.

The specific structures of the manufacturing method and the lithium foil laminating apparatus of the present invention are not limited to the above-mentioned embodiment, and may be appropriately changed without departing from the scope of the present invention. Is.

[0018]

As is apparent from the above description, according to the present invention, the lithium ingot is fed between the rolls, rolled into a foil shape and superposed on the electrodes, and these are pressed and integrated, Lamination of lithium on the electrodes of the lithium secondary battery can be performed while suppressing oxidation of lithium to the minimum.
Moreover, since the electrode is formed by cutting by cutting a blade having a planar shape along the contour of the electrode with the continuous electrode, the generation of chips generated at the time of cutting is minimized, and a short circuit between electrodes is made. The cause of can be reduced as much as possible. Further, a rolling means for supplying a lithium ingot between the rolls and rolling it into a foil shape, and a lithium foil fed from between the rolls of the rolling means are superposed on the continuously manufactured electrodes and pressed. The rolling means is provided on both sides of the electrode that is continuously fed, and the pressing means is a pair of rollers that compresses the electrode and the lithium foil fed to both sides thereof from both sides. With the lithium foil laminating apparatus consisting of, it is possible to efficiently produce a lithium secondary battery in which a lithium foil is provided on the surface of an electrode.

[Brief description of drawings]

FIG. 1 is a process explanatory diagram of an embodiment.

FIG. 2 is a side view of a lithium foil laminating device.

FIG. 3 is a perspective view of a modified example of a pressure bonding roll.

FIG. 4 is a plan view of a blade used in one embodiment.

5 is a plan view of an electrode cut by the blade of FIG.

FIG. 6 is a perspective view showing a cross section of a part of a conventional lithium secondary battery.

[Explanation of symbols]

2 Positive electrode (electrode) 3 Negative electrode (electrode) 2a Positive electrode current collector 2b Positive electrode layer 12a positive electrode tab 13a negative electrode tab 21 Lithium foil 22 Crimping roll 23 cutting means 24 cutter 25 separator 30 supply means 31 Lithium 33 Rolling roll 40 blades

Continued front page    F term (reference) 5H029 AJ12 AJ13 AJ14 AK06 AL12                       BJ02 BJ13 BJ15 BJ24 CJ03                       CJ04 CJ06 CJ16 CJ30 DJ14                       HJ12                 5H050 AA15 AA18 AA19 BA16 BA17                       CA15 CB12 FA04 FA15 GA03                       GA04 GA08 GA18 GA29 HA12

Claims (7)

[Claims] 1. A method of manufacturing a secondary battery, wherein a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, a step of manufacturing the electrodes in a continuous state in a predetermined direction, and a lithium block between rolls. A step of supplying and rolling into a foil shape, a step of superposing the lithium foil fed from between the rolls on the continuous electrode, and a step of applying the superposed electrode and the lithium foil in the thickness direction. And a step of integrating by pressing. 2. A method of manufacturing a secondary battery, in which a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, a step of continuously manufacturing the electrodes in a predetermined direction, and continuously manufactured electrodes. And a cutting step of cutting the electrode into predetermined lengths, and punching for cutting by cutting a blade having a planar shape along the contour of the electrode excluding a cutting line by the cutting step with the continuous electrode. A method of manufacturing a secondary battery, wherein the steps are performed alternately with the cutting step. 3. A method of manufacturing a secondary battery in which a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, and a step of manufacturing the electrode and a step of alternately arranging the positive electrode and the negative electrode. , A step of arranging a continuous separator in the form of a long sheet along one side surface of one of the electrodes and the other side surface of the other electrode, and the separator of the positive electrode and the negative electrode. A method of manufacturing a secondary battery, characterized by comprising a step of interposing them and superimposing them. 4. A method of manufacturing a secondary battery, wherein a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, and a step of manufacturing the electrodes continuously in a predetermined direction,
A step of supplying a lithium ingot between rolls to roll it into a foil, a step of superposing the lithium foil fed from between the rolls on the continuous electrode, and the superposed electrode and lithium foil. A lithium lamination step of producing an electrode in which a lithium foil is laminated by a step of pressurizing and integrating in a thickness direction, and a cutting step of cutting the continuously produced electrode into predetermined lengths, An electrode cutting step of alternately performing a punching step of cutting a blade having a planar shape along the contour of the electrode excluding the cutting line by the cutting step by intersecting the continuous electrode with the cutting step, the positive electrode and A step of alternately arranging the electrodes of the negative electrode, a step of arranging one of the side surfaces of one of the electrodes and the other side surface of the other electrode, and arranging the continuous separators in a long sheet shape, Serial positive electrode and method of manufacturing a secondary battery, characterized by performing at least two steps of the electrode assembly process comprising the step of bringing the negative electrode superimposed by interposing between the separators. 5. A secondary battery manufacturing apparatus in which a positive electrode and a negative electrode are housed in a battery case together with an electrolytic solution, and a rolling unit for feeding a lithium ingot between rolls and rolling it into a foil, and the rolling unit. Of the lithium foil sent from between the rolls and the pressurizing means for superposing and pressurizing on the electrode produced continuously, the rolling means, on both sides of the electrode continuously sent out. An apparatus for manufacturing a secondary battery electrode, wherein each of the pressurizing means is provided with a pair of rollers for compressing an electrode and a lithium foil sent to both sides thereof from both sides. 6. The apparatus for manufacturing a secondary battery electrode according to claim 5, wherein the roller has irregularities on an outer peripheral surface. 7. An apparatus for manufacturing a secondary battery electrode according to claim 5, wherein an elastic deformation layer is provided on the surface of the roller.