JP2004247064A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery reducing an obstacle of an adhesive of an insulating tape for preventing an internal short circuit to the manufacturing equipment of a spiral electrode body and to assembly work, and eliminating a bad influence on battery specifications. <P>SOLUTION: The nonaqueous electrolyte secondary battery has the spiral electrode body 10A formed by spirally winding a positive electrode 15 having a positive electrode mix coated part 15a and a positive electrode mix uncoated exposed part 15b on metal core foil and a negative electrode 12 having a negative electrode mix coated part 12a and a negative electrode mix uncoated exposed part 12b by a separator, and a first insulating tape 16 is stuck in a position on the back side of an electrode on the outermost circumferential side of the spiral electrode body 10A, in a boundary between the mix coated part and the exposed part of the electrode, and corresponding to the final end of the mix coated part of the counter electrode, and a second insulating tape (not shown in Fig.) is stuck so as to cover a part where an adhesive surface 16b of the first insulating tape 16 is exposed from the core foil 16. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly, to reduce the possibility that an adhesive of an insulating tape for preventing internal short-circuit will hinder a spiral electrode assembly manufacturing apparatus and a battery assembling operation, The present invention relates to a non-aqueous electrolyte secondary battery which has no adverse effect on water.
[0002]
[Prior art]
With the rapid spread of portable electronic devices, the required specifications for batteries used in them have become stricter year by year. Particularly, small and thin type, high capacity, excellent cycle characteristics, and stable performance are required. In the field of secondary batteries, attention has been paid to lithium secondary batteries having a higher energy density than other batteries, and the proportion occupied by the lithium secondary batteries has shown a large growth in the secondary battery market.
[0003]
This lithium secondary battery has a negative electrode in which a negative electrode active material is coated on both surfaces of a negative electrode current collector made of a strip-shaped copper foil and the like, and a negative electrode current collector made of a strip-shaped aluminum foil and the like on both surfaces. Between the positive electrode coated with the positive electrode active material in the form of a film, via a separator made of a microporous polypropylene film or the like, the negative electrode and the positive electrode are wound in a cylindrical or elliptical shape while being insulated from each other. In the case of a type battery, the wound electrode body is further crushed to form a flat shape, and a negative electrode lead and a positive electrode lead are connected to predetermined portions of the negative electrode and the positive electrode, respectively, and housed in a can body of a predetermined shape. ing.
However, in the electrode group of the electrode body wound via the separator, an internal short circuit occurs between the electrodes when the separator is damaged or the separator penetrates due to burrs, dust, or the like. Therefore, for example, measures are taken to prevent an internal short circuit by applying an insulating coating to at least a portion of the positive electrode, the separator, and the negative electrode that faces the positive electrode lead. (For example, Patent Documents 1 and 2).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-42881 (page 3 right orchid to page 4 left column, FIG. 8)
[Patent Document 2]
Japanese Patent Application Laid-Open No. Hei 10-241737 (FIGS. 1, 3, 5, and 7)
[0005]
Patent Documents 1 and 2 disclose a method of positioning a negative electrode of a predetermined electrode body formed in a state where a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and causing a short circuit with the positive electrode when the electrode body is formed. A secondary battery is described in which a predetermined insulating tape thicker than the height of the burr generated on the positive electrode side and / or the negative electrode side is attached to at least one surface of the positioned negative electrode at an expected short-circuit with the positive electrode. Have been.
[0006]
[Problems to be solved by the invention]
However, the adhesive surface of the insulating tape for preventing an internal short-circuit applied to such a short-circuit supposed place may be exposed on the surface of the electrode when the spiral electrode is formed. 6A and 6B show a conventional technique. FIG. 6A is a perspective view of a spiral electrode body taken out of a can body, and FIG. 6B is a side view of the spiral electrode body.
In the spiral electrode body 10, a positive electrode and a negative electrode are wound via a separator 11 such that the positive electrode is located on the outermost periphery. Reference numeral 13 denotes a negative electrode lead, 15c denotes a cut portion provided on the positive electrode core so as to become a positive electrode lead, and 20 denotes an insulating tape for fixing the final edge of the positive electrode.
As shown in FIG. 6, the insulating tape 16 for preventing short-circuiting must cover all the expected short-circuited portions, and therefore, an insulating tape larger than the expected short-circuited portion is attached. Of course, it is desirable to attach an insulating tape of the same size as the assumed location, but it is impossible to attach an insulating tape of the same size due to the selection of the expected short-circuit location and the attaching work, etc., and inevitably attach a large insulating tape. I had to help. Therefore, on the outer surface of the spiral electrode body, the insulating tape protrudes in the vertical direction of the vertical width of the separator, and the protruding portion generates an exposed portion of the adhesive of the insulating tape.
[0007]
Then, since the adhesive 16b, 16b 'at the protruding portion of the insulating tape 16 is exposed, dust, dirt, etc. easily adhere thereto, and also when the adhesive is inserted into the outer can with the adhesive being exposed, In some cases, the adhesive adhered to the outer can and insertion was difficult. Further, when a spiral electrode body manufacturing apparatus (not shown), for example, a spiral electrode body is crushed and formed into a flat shape or the like, an adhesive adheres to a press machine or the like. Therefore, it is necessary to handle the electrode body so that dust and dirt do not adhere thereto, and the insertion work into the outer can is hindered. Further, a press machine or the like operates the manufacturing apparatus to remove the adhesive. Had to pause and clean frequently.
The present invention has been made to solve the problems of the prior art,
SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery in which an adhesive of an insulating tape for preventing internal short-circuit reduces an obstacle to a spiral electrode assembly manufacturing apparatus and an assembling operation and has no adverse effect on battery specifications. It is in.
[0008]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following means. That is, the non-aqueous electrolyte secondary battery of the present invention,
A positive electrode having a portion where a positive electrode mixture containing a positive electrode active material that absorbs and releases lithium ions on a metal core foil and an uncoated exposed portion,
A negative electrode having a portion coated with a negative electrode mixture containing a negative electrode active material that occludes and releases lithium ions on a metal core foil and an uncoated exposed portion,
Is laminated via a separator, in a non-aqueous electrolyte secondary battery having a spirally wound electrode body,
On the back surface of the outermost pole on the outermost peripheral side of the spiral electrode body, a first boundary is provided at a position corresponding to the boundary between the mixture application portion and the exposed portion of the pole and corresponding to the end of the mixture application portion of the opposite electrode. Insulating tape is affixed,
Furthermore, a second insulating tape is attached so that the adhesive surface of the first insulating tape covers a portion protruding from the core foil.
Further, it is preferable that the second insulating tape is an insulating tape for fixing a winding end of the spiral electrode body.
[0009]
In this nonaqueous electrolyte secondary battery, since the adhesive of the first insulating tape protruding from the core foil is covered with the second insulating tape, dust and dirt do not adhere to the adhesive, and It becomes easy to insert the spiral electrode body into the outer can.
Further, the adhesive does not adhere to a press machine or the like when a spiral electrode body manufacturing apparatus, for example, a spiral electrode body is crushed. Therefore, it is not necessary for the press machine or the like to temporarily stop the operation of the manufacturing apparatus or to frequently clean the apparatus to remove the adhesive as in the prior art, and it is possible to improve the production efficiency of the spiral electrode body.
Further, by covering the adhesive surface of the first insulating tape by using the second insulating tape also as the insulating tape for fixing the winding end, the manufacturing process can be reduced, and the amount of the insulating tape to be applied can be reduced. .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a nonaqueous electrolyte secondary battery according to the present invention will be described with reference to the drawings. FIG. 1 shows a nonaqueous electrolyte secondary battery according to an embodiment of the present invention. FIG. 1 (a) is a partially perspective perspective view thereof, and FIG. 1 (b) is a front view of a spiral electrode body of FIG. 1 (a). FIG. 2 is a plan view showing a state before the spiral electrode body of FIG. 1B is wound, and FIG. 3 is an exploded view of the laminate of FIG. 3B is a plan view of the negative electrode plate, FIG. 3C is a plan view of the separator, FIG. 3D is a plan view of the insulating tape, and FIG. 3E is a plan view of the positive electrode plate. FIG.
[0011]
As shown in FIG. 1, the non-aqueous electrolyte secondary battery 1 includes a spiral electrode body 10A, a rectangular outer can 2 accommodating the electrode body 10A, and a sealing plate 3 for sealing an opening edge 2a of the outer can. The sealing plate 4 is welded by a laser or the like with the positive electrode lead 15c 'interposed between the opening edge 2a and the sealing plate 3, and then the non-water is inserted into the exterior can 2 through the through hole of the sealing plate 3. Electrolyte is injected and the battery cap 4 is fixed.
[0012]
As shown in FIGS. 2 and 3, the spiral electrode body 10A includes a negative electrode plate 12, a positive electrode plate 15, and a separator 11, each of which is formed of a strip having a predetermined width and length. The separator 11b is interposed between the negative electrode plate 12 and the positive electrode plate 15, and the positive electrode plate 15 is wound so as to be located at the outermost peripheral portion.
The separator 11 is a spiral electrode body, and two separators 11a and 11b are used. The separator 11 is a belt-shaped body wider than the negative electrode plate 12 and the positive electrode plate 15, and is formed of a microporous polypropylene film or the like.
[0013]
The negative electrode plate 12 has a negative electrode active material layer 12a obtained by applying a predetermined process to a core 12A made of a copper foil or the like and applying a negative electrode mixture containing a negative electrode active material that occludes and releases lithium ions to the front and back surfaces thereof. The exposed portion 12b is not coated with an active material, and the negative electrode lead 13 is connected to the exposed portion 12b of the core 12A.
[0014]
The first insulating tape 16 includes an insulating base material 16A having a vertical width shorter than the vertical width of the separator 11 and a predetermined horizontal width, and an adhesive 16B attached to one surface of the insulating base material.
[0015]
The positive electrode plate 15 has a core body 15A made of aluminum foil or the like, and a positive electrode mixture containing a positive electrode active material for absorbing and releasing lithium ions applied to the front and back surfaces thereof, and a positive electrode active material layer 15a subjected to a predetermined process; The exposed portion 15b to which the active material is not applied is formed, and the core of the exposed portion 15b has a cut portion 15c formed in the vicinity of its tip. The cut portion 15c is used as a positive electrode lead 15c 'by being bent from the root portion and sandwiched between the sealing plate 3 when sealing the opening edge 2a of the outer can.
[0016]
Using the negative electrode plate 12, the positive electrode plate 15, and the separator 11, the spiral electrode body 10A is manufactured by the following method.
First, the separators 11a and 11b are aligned with the cylindrical core of the winding device, and the leading end is wound up. The negative electrode plate 12 and the positive electrode plate 15 are placed on the separator 11a and between the separators 11a and 11b and wound. Turn. During the winding, the final end (each of the front and back sides) of the positive electrode active material layer 15a of the positive electrode plate is detected, and the first insulating tape 16 is attached to this portion. The portion to which the insulating tape 16 is attached is designed to face the end of the negative electrode active material layer at the end of winding of the negative electrode plate 12 with the separator interposed therebetween. Then, the winding is completed so that the positive electrode plate 15 is located at the outermost periphery, and the ends are fixed with insulating tape. At this time, one portion of the first insulating tape 16 applied at two locations is attached to the back surface of the outermost positive electrode plate 15, so that part of the adhesive 16B of the first insulating tape is It sticks out from the width direction of the body and the adhesive surface is exposed. Reference numerals 16b and 16b 'indicate the protruding adhesive portion (see FIG. 2).
Although the first insulating tape was attached at the time of producing the spiral electrode body, it may be attached to the positive electrode plate in advance. Then, after the exposed portion of the adhesive surface of the first insulating tape is covered with the second insulating tape 17, in the case of a rectangular battery, it is molded into a flat shape by a press.
[0017]
The spiral electrode bodies shown in FIGS. 1, 4, and 5 are all manufactured by using the above-described method with the positive electrode plates 15 having different lengths. That is, the spiral electrode body 10A in FIG. 1 is a length of the end portion of the positive electrode plate 15 was prepared using L ₃ only longer than conventional. The length L _3, the horizontal width dimension L ₁ of the spiral electrode body 10A to a length obtained by adding a predetermined length L _2, the predetermined length L ₂ is first to fasten the ends of the positive electrode plate 15 The length is almost the same as the width of the insulating tape. Using a positive electrode plate 15 that the tip extends by a length L _3, the separator 11a, the negative electrode 12, positive electrode plate 15, the positive electrode plate 15 are sequentially stacked separator 11b is wound so as to be located in the outermost peripheral portion The positive electrode plate 15 makes a half turn around the spiral electrode body 10A, and its tip reaches one side surface of the electrode body, that is, the place where the first insulating tape 16 is attached. Therefore, a second insulating tape 17 having a predetermined width and length is used. The second insulating tape 17 covers the front end of the positive electrode plate 15 and the adhesives 16b, 16b ′ of the first insulating tape. Affix so as to cover the part.
[0018]
Then, the winding end of the positive electrode plate is fixed by the second insulating tape 17, and at the same time, the protruding adhesives 16b and 16b 'can be covered, so that the manufacturing process can be reduced. Further, since the adhesive is not exposed, dust, dust and the like do not adhere to this portion. Furthermore, when a spiral electrode body is manufactured, for example, when a spiral electrode body is pressed, the adhesive does not adhere to a press machine or the like.
[0019]
Further, the second insulating tape may be attached to the adhesive exposed portion of the first insulating tape without extending the length of the positive electrode plate 15. The spiral electrode body 10B shown in FIG. 3 is one in which one vertically long second insulating tape 17 is adhered to the adhesive exposed portion of the first insulating tape.
In addition, the spiral electrode body 10C in FIG. 4 is obtained by dividing the insulating tape and affixing the divided insulating tape pieces 18a and 18b. Reference numeral 20 denotes an insulating tape for fixing the winding end of the positive electrode plate.
According to these spiral electrode bodies 10B and 10C, the desired function can be exhibited without extending the tip of the positive electrode plate, and the insulating tape can be saved.
[0020]
【Example】
<Preparation of positive electrode plate>
A positive electrode mixture slurry is prepared by kneading a positive electrode active material composed of lithium cobalt oxide, carbon black as a conductive agent, and polyvinylidene fluoride as a binder using N-methylpyrrolidone (NMP). Was applied on both sides of a positive electrode core made of aluminum foil having a thickness of 15 μm in a predetermined amount. At this time, a portion (core exposed portion) where the mixture slurry was not applied was also prepared for attaching the current collecting tab. After evaporating NMP in a drying oven, the NMP was compressed to a predetermined thickness and cut and wound into a predetermined width to produce a positive electrode hoop.
[0021]
<Preparation of negative electrode plate>
A negative electrode active material composed of graphite and polyvinylidene fluoride as a binder are kneaded using NMP to prepare a negative electrode mixture slurry, and the negative electrode mixture slurry is coated on both sides of a 10 μm-thick negative electrode core made of copper foil. Was applied in a predetermined amount. Thereafter, a negative electrode hoop was produced in the same manner as the positive electrode.
[0022]
<Preparation of electrode body>
The hoop-shaped separator, the positive electrode plate, and the negative electrode plate were wound around a cylindrical core provided at the winding position of the winding machine in the order of the separator, the negative electrode, and the positive electrode to produce a spiral electrode body. The hoop-shaped separator, the negative electrode plate and the positive electrode plate were cut off from the hoop at a predetermined size and wound.
[0023]
<Attaching insulating tape>
At the time of winding by the winding machine, the negative electrode mixture application portion and the core exposed portion are detected by a sensor in the path to the core, and the first insulating tape is applied to the exposed portion of the positive electrode core at the corresponding position. Affixed. The first insulating tape for the purpose of preventing a short circuit is attached to the expected short circuit position during the above-mentioned winding, but is not limited thereto, and may be applied before forming the hoop shape. It is also possible to attach.
[0024]
After the winding, an insulating tape for fixing the winding end of the electrode body was attached. The attaching position was changed as follows, and the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Example 1 were produced.
(Example 1)
As shown in FIG. 4 or 5, the insulating tape for fixing the winding end of the electrode body and the second insulating tape are separate bodies.
(Example 2)
As shown in FIG. 1, the positive electrode core is wound half a circumference longer than that shown in FIGS. 4 and 5, and the insulating tape for fixing the winding end of the electrode body is also used as the second insulating tape.
(Comparative Example 1)
In the example shown in FIG. 4 or 5, an insulating tape for fixing the winding end of the electrode body is used, but the second insulating tape is not used.
[0025]
According to the production methods of Examples 1 and 2 and Comparative Example 1, the cleaning frequency of the press plate was as shown in Table 1 below.
Table 1
Example 1
Example 2
Comparative Example 1
Cleaning frequency 500 shots every 500 shots every 50 shots
From this result, in the electrode body to which the second insulating tape was attached, the frequency of cleaning was significantly reduced because the adhesive did not adhere to the plate. In addition, in the specification in which the positive electrode core foil is wound half a circumference long, the exposure of the adhesive is prevented by also using the insulating tape for fixing the winding end of the electrode as the second insulating tape. Since there is no adhesion, the frequency of cleaning has been significantly reduced.
[0027]
【The invention's effect】
As described above, according to the present invention, dust and dirt do not adhere to the adhesive of the insulating tape for short circuit prevention, and insertion into the outer can during battery assembly is simplified. In addition, since the adhesive does not adhere to a press machine or the like when a spiral electrode body manufacturing apparatus, for example, a spiral electrode body is crushed, it is necessary to remove the adhesive from the press machine or the like as in the related art. In addition, there is no need to temporarily stop the operation of the manufacturing apparatus or perform frequent cleaning, and it is possible to improve the production efficiency of the spiral electrode body.
[0028]
Further, by covering the adhesive surface of the first insulating tape also as the insulating tape for fixing the winding end of the electrode body, the manufacturing process can be reduced, and the insulating tape to be stuck can be reduced.
[Brief description of the drawings]
1 shows a non-aqueous electrolyte secondary battery according to an embodiment of the present invention, FIG. 1 (a) is a partially transparent perspective view, and FIG. 1 (b) is a front view of a spiral electrode body of FIG. 1 (a). FIG.
FIG. 2 is a plan view showing a state before the spiral electrode body of FIG. 1B is wound.
3 (a) is a plan view of a separator, FIG. 3 (b) is a plan view of a negative electrode plate, and FIG. 3 (c) is a plan view of a separator. FIG. 3D is a plan view of the insulating tape, and FIG. 3E is a plan view of the positive electrode plate.
FIG. 4 is a front view showing a spiral electrode body used for a nonaqueous electrolyte secondary battery according to a second embodiment of the present invention.
FIG. 5 is a front view showing a spiral electrode body used for a nonaqueous electrolyte secondary battery according to a third embodiment of the present invention.
6A and 6B show a conventional spiral electrode body, wherein FIG. 6A is a front view and FIG. 6B is a side view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 2 Outer can 10, 10A, 10B, 10C Spiral electrode body 11 Separator 12 Negative electrode plate 12a Negative electrode active material layer 12b Core exposed part 15 Positive electrode plate 15a Positive electrode active material layer 15b Core exposed part 16 Insulation Tape (first insulating tape)
16b, 16b 'Adhesive exposed portion 17, 18a, 18b Insulating tape (second insulating tape)
20 Insulating tape

Claims (2)

A positive electrode having a portion where a positive electrode mixture containing a positive electrode active material that absorbs and releases lithium ions on a metal core foil and an uncoated exposed portion,
A negative electrode having a portion coated with a negative electrode mixture containing a negative electrode active material that occludes and releases lithium ions on a metal core foil and an uncoated exposed portion,
Is laminated via a separator, in a non-aqueous electrolyte secondary battery having a spirally wound electrode body,
On the back surface of the outermost pole on the outermost peripheral side of the spiral electrode body, a first boundary is provided at a position corresponding to the boundary between the mixture application portion and the exposed portion of the pole and corresponding to the end of the mixture application portion of the opposite electrode. Insulating tape is affixed,
A non-aqueous electrolyte secondary battery, wherein a second insulating tape is attached so that an adhesive surface of the first insulating tape covers a portion protruding from the core foil. 2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the second insulating tape is an insulating tape for fixing a winding end portion of the spiral electrode body. 3.

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