KR100319096B1 - Litium ion polymer battery and the manufacturing method of the same - Google Patents

Abstract

A lithium ion polymer battery and a method of manufacturing the same are disclosed. The battery includes at least one unit electrode having a structure in which a positive electrode plate, a separator, and a negative electrode plate are sequentially stacked. The battery is inserted between at least one of the separator and the positive electrode plate and between the separator and the negative electrode plate and positioned at the electrode cutting surface at the edge of the unit electrode. At least one tape is provided to prevent the burrs generated at the cutting surface of the positive electrode plate or the negative electrode plate from contacting the other electrode plate when the electrode plate is cut. Such a lithium ion polymer battery and its manufacturing method have the advantage that the defective rate can be significantly reduced by preventing the battery short circuit caused by the burr generated during the battery cutting operation.

Description

Lithium ion polymer battery and its manufacturing method

The present invention relates to a lithium ion polymer battery and a method for manufacturing the same, and more particularly, to a lithium ion polymer battery having a structure capable of preventing a short circuit caused by burrs generated during cutting of a plate and a method for manufacturing the same.

As electronic devices, especially camcorders, cellular phones, and notebook computers, are rapidly miniaturized, lightened, and wireless, as a driving power source for these electronic devices, small, lightweight, high energy density secondary batteries ), The demand for) is increasing. In this respect, especially lithium ion secondary batteries have attracted attention.

A lithium ion secondary battery capable of charging and discharging includes a positive electrode, a negative electrode, and an electrolyte, and there are a liquid lithium ion secondary battery composed of a liquid organic solvent and a polymer lithium ion secondary battery composed of a polymer according to the type of the electrolyte.

The lithium secondary battery has an operating voltage of 3.6 V, which is about three times that of a nickel-cadmium (Ni-Cd) battery or a nickel-hydrogen (Ni-MH) battery, which is widely used as a power source for electronic equipment, and has an excellent energy density per unit weight. It is rapidly expanding at this point.

Here, lithium secondary batteries are manufactured in various shapes, and typical shapes include cylindrical and square shapes mainly used in lithium-ion batteries. On the other hand, a lithium-polymer battery is flexible and its shape is relatively free.

Accordingly, in recent years, lithium-polymer batteries have excellent safety and freedom of shape, are light in weight, and are advantageous for slimming and trending of portable electronic devices. Therefore, various studies have been conducted.

1 is a schematic exploded perspective view showing the configuration of a lithium ion polymer battery of such a lithium ion secondary battery.

Referring to the drawings, the lithium ion polymer battery 10 capable of charging and discharging includes a positive electrode plate inserted into upper and lower cases 11a and 11b and a space provided in the upper and lower cases 11a and 11b. 12 and an electrode assembly 15 interposed between the negative electrode plate 13 and the negative electrode plate 13, and the positive electrode tab and the negative electrode tab 16a, which are drawn out from the ends of the positive electrode plate 12 and the negative electrode plate 13, 16b), and positive and negative terminals 17a and 17b connected to the tabs 16a and 16b.

In the above battery structure, in particular, the electrode assembly 15 has a configuration in which a plurality of unit electrodes are stacked. The unit electrodes may be stacked in the order of the positive electrode plate-separator-negative plate or the positive electrode plate-separator-negative plate-separator-anode plate. As described above, there are various methods of forming one electrode assembly by stacking a plurality of unit electrodes.

First, the lamination method disclosed in US Pat. No. 5,478,668 is made to overlap with the corrugation while laminating the positive electrode plate, the separator, and the negative electrode plate. However, this manifolding (manifolding), there is a problem that when the lamination of the pole plates with each other, the laminated part is separated, or short circuit occurs in the corrugated portion.

Secondly, the stacking method is a method of forming a unit electrode by cutting a positive electrode plate, a separator, and a negative electrode plate to a predetermined size and then laminating it, which is disadvantageous in mass production.

On the other hand, in order to increase productivity, a method of continuously feeding and laminating a strip-shaped negative electrode plate, a separator and a positive electrode plate, and cutting the strip laminate to form a unit electrode is performed. In this method, however, a problem arises in that the burrs of the positive electrode plate or the negative electrode plate generated at the time of cutting the strip laminate come into contact with electrodes having different polarities, thereby increasing the risk of short circuiting of the battery.

The present invention has been made to solve the above problems, and the lithium ion polymer battery and its fabrication improved in the construction and process so as to prevent the battery short circuit caused by the burr generated in the cutting portion of the electrode during the continuous process Its purpose is to provide a method.

1 is a perspective view of a conventional lithium ion polymer battery.

2A is a perspective view of a unit electrode in a first embodiment of a lithium ion polymer battery according to the present invention.

FIG. 2B is a cross-sectional view taken along the line 'II-II' of FIG. 2A.

3A is a perspective view of a unit electrode in a second embodiment of a lithium ion polymer battery according to the present invention.

3B is a cross-sectional view taken along the line 'III-III' of FIG. 3A.

4a to 8b sequentially show the process of the first embodiment of the method for manufacturing a lithium ion polymer battery according to the present invention,

4A, 4B, and 4C show a positive electrode strip, a negative electrode strip, and a separator strip, respectively;

5 shows a step of forming a separator-cathode plate-separator laminate,

6 shows a tape attach process,

FIG. 7 illustrates a process of forming a cathode plate-separator-anode plate-separator-anode plate laminate,

8A illustrates the cutting process,

FIG. 8B is an enlarged view illustrating a cut portion in the process of FIG. 8A.

9 schematically illustrates a process of a second embodiment of a method of manufacturing a lithium ion polymer battery according to the present invention.

<Explanation of symbols for the main parts of the drawings>

21,31 ... positive plate 22,32 ... separator

23, 33 ... cathode plates 26a, 26b, 26c, 26d ... tape

29 ...

41.Anode plate strip 42 ... Anode plate strip

43 ... separator strip

The lithium ion polymer battery of the present invention for achieving the above object comprises at least one unit electrode having a structure in which a positive electrode plate, a separator, a negative electrode plate are sequentially stacked,

At least one tape is inserted between at least one of the separator and the positive electrode plate and between the separator and the negative electrode plate and positioned on the electrode cutting surface of the edge of the unit electrode, so that a burr generated at the cutting surface of the positive electrode plate or the negative electrode plate is cut on the other electrode plate. Preventing contact.

The unit electrode has a bi-cell structure consisting of two separators each laminated on both sides of one cathode plate and two anode plates each laminated on the outer side of each separator, wherein the tape is disposed between the separator and the anode. It is preferable to insert each.

In addition, the material of the tape is preferably polyethylene, polypropylene, Teflon, ABS rubber.

The tape is also preferably made of an elastic material.

And the width of the tape is preferably between 1mm and 10mm.

In order to achieve the above object, a method of manufacturing a lithium ion polymer battery according to the present invention includes a first step of making a positive electrode strip, a negative electrode strip, and a separator strip, and laminating the separator strips on both sides of the negative electrode strip and pressing them. A second step, a third step of attaching the tape to the outer surface of each separator strip at a predetermined interval, and a fourth step of laminating and compressing the positive electrode strip on the outer side of the separator strip to which the tape is attached, respectively; And a fifth step of cutting the tape attaching portion to form a plurality of unit electrodes.

And it is preferred that the third step is performed before the second step.

Another method of manufacturing a lithium ion polymer battery of the present invention for achieving the above object, the step of making a positive electrode strip, a negative electrode strip and a separator strip, and a constant on the outside of at least one of the positive electrode plate strip, negative electrode plate strip, separator strip. Attaching the tapes at intervals, and laminating and compressing the positive electrode strip, the separator strip, and the negative electrode strip in order, and the tapes are interposed between the positive electrode strip and the separator strip or between the separator strip and the negative electrode strip. And pressing to cut the tape attachment portion of the strip stack to form a plurality of unit electrodes.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the embodiment described below, since the general structure of the battery except for the unit electrode is the same as that shown in Figure 1, a detailed description thereof will be omitted.

2A and 2B are a perspective view and a cross-sectional view of a unit electrode in a first embodiment of a lithium ion polymer battery according to the present invention.

As illustrated, the unit electrode 20 of the present embodiment has a structure in which a positive electrode plate 21, a separator 22, a negative electrode plate 23, a separator 22, and a positive electrode plate 21 are sequentially stacked, that is, a bicell ( bicell) structure. That is, in the unit cell 20, one negative electrode plate 23 is positioned at the center, and two separators 22 are laminated on both sides thereof, and two positive electrode plates 21 are disposed on the outer surface of each separator 22. Is laminated. The positive electrode plate 21 and the negative electrode plate 23 are formed by coating active materials on both sides of a perforated thin plate, and the positive electrode tab 21a and the negative electrode tab 23a are formed at ends of the positive electrode plate 21 and the negative electrode plate 23. ) Are each provided.

As shown in FIG. 2B, short-circuit prevention tapes 26a, 26b, 26c, and 26d are inserted into cutting surfaces A and B located at both sides of the edge of the unit electrode 20. The tapes 26a, 26b, 26c, and 26d are shown in the figure as being inserted between the separator 22 and the positive electrode plate 21, respectively, but the tape is interposed between the separator 22 and the negative electrode plate 23. It can also be inserted. However, due to problems in the manufacturing process, the former arrangement structure may be more advantageous than the latter. The tapes 26a, 26b, 26c, and 26d have a function of preventing burrs 29 generated in the positive electrode plate 21 or the negative electrode plate 23 extending in the vertical direction from contacting other adjacent electrode plates when the electrode is cut. do. The function of such tapes 26a, 26b, 26c, and 26d increases the distance between adjacent positive and negative plates, further preventing the extension of the burr 29 in the vertical direction by using the elastic force of the tape. As can be achieved by the above, it will be described in more detail with respect to the manufacturing method described below.

The tapes 26a, 26b, 26c, and 26d are preferably made of a material having good elasticity. In particular, the material of the tapes 26a, 26b, 26c, 26d may be made of polyethylene, polypropylene, teflon or ABS rubber. As shown, the width C of the tapes 26a, 26b, 26c, 26d is preferably between 1 mm and 10 mm. If the widths C of the tapes 26a, 26b, 26c, and 26d are too large, they will invade the discharge space of the electrode, which is disadvantageous. However, the minimum width of the tape will be limited by the size of the sensor (not shown) capable of sensing the tapes 26a, 26b, 26c, and 26d in the tape attaching and cutting processes.

3A and 3B illustrate another embodiment of a unit electrode of a lithium ion polymer battery according to the present invention.

As shown, the unit electrode 30 of the lithium ion polymer battery according to the present embodiment has a structure in which the positive electrode plate 31, the separator 32, and the negative electrode plate 33 are sequentially stacked. The positive electrode plate 31 and the negative electrode plate 33 are coated with active materials on both sides of the perforated thin plate, and the positive electrode tab 31a and the negative electrode tab 33a are provided at ends of the positive electrode plate 31 and the negative electrode plate 33. .

As shown in FIG. 3B, short-circuit prevention tapes 36a, 36b, 36c, and 36d are inserted into cutting surfaces A and B located at both sides of the edge of the unit electrode. The tapes 36a, 36b, 36c, and 36d are inserted between the separator 32 and the positive electrode plate 31 and / or between the separator 32 and the negative electrode plate 33, respectively, to generate burrs 39 generated during electrode cutting. Prevent contact with another adjacent electrode.

The functions, shapes, and materials of the tapes 36a, 36b, 36c, and 36d of this embodiment are essentially the same as the tapes 26a, 26b, 26c, and 26d of the first embodiment shown in Figs. 2A and 2B. That is, the tapes 36a, 36b, 36c, 36d are made of a material having good elasticity, in particular, may be made of polyethylene, polypropylene, teflon or ABS rubber. The widths C of the tapes 36a, 36b, 36c, and 36d are preferably between 1 mm and 10 mm.

Hereinafter, two preferred embodiments of the lithium ion polymer battery manufacturing method according to the present invention will be described in detail.

The first embodiment illustrated in FIGS. 4A to 8B relates to a method of manufacturing a unit cell having a bi-cell structure shown in FIGS. 2A and 2B.

4A to 4B are plan views of the positive electrode plate strip 41, the negative electrode strip 42, and the separator strip 43 manufactured in the first step of the manufacturing method according to the present embodiment.

In order to manufacture the positive electrode strip 41, 50 g of lithium oxide such as lithium cobalt dioxide or lithium manganese tetraoxide and 4 g of conductive carbon black are mixed in a powder state, and 7 g of polyvinylidene fluoride is mixed therein as a binder. The mixture is dissolved in 100 g of N-methyl pyrolidene to form a uniform mixed solution, and 10 g of a plasticizer DBP (dibutylphthalate) is added thereto. This mixed solution is applied to a perforated aluminum foil strip (thickness 20 μm) and dried, and the edges of the aluminum strip are punched to produce a plurality of positive electrode tabs 41a, thereby producing a positive electrode plate as shown in FIG. 4A. The strip 41 is completed.

In order to manufacture the negative electrode strip 42, 30 g of graphite as an active material and 1 g of carbon black as a conductor are mixed in a powder state, and 5 g of polyvinylidene fluoride is added thereto as a binder. The mixture is then dissolved in 50 g of enmethylpyrrolidone, and finally, plasticizer DBP is added to form a uniform mixed solution. This mixed solution is then applied to a perforated copper strip (thickness 18 μm) and then dried. And by punching the edges of the copper strip to produce a plurality of negative electrode tabs 42a, the positive electrode strip 42 as shown in FIG. 4B is completed.

In order to manufacture the separator strip 43, 30 g of polyvinylidene fluoride and 20 g of silica are dissolved in 300 ml of acetone to form a coating solution, and 30 g of a plasticizer DBP is added to the mixture, followed by uniform mixing. This mixed solution is then cast with a doctor braid device to produce a film having a thickness of 50 μm.

The broken line p in FIGS. 4A-4C is an imaginary cut line that must be cut in a subsequent process to make a unit cell.

In the second step, as shown in FIG. 5, the separator strips 43 are respectively supplied to the upper and lower sides of the negative electrode strip 42 prepared in the first step, and laminated on the heated roll 50 to be compressed. By such a process, a laminated strip composed of the separator 43, the negative electrode plate 42, and the separator 43 is provided.

And as shown in FIG. 6 as a third step. A plurality of tapes 45 are attached to the cut lines on the upper and lower sides of the laminate made in FIG. 5. To this end, the laminated strip of the separator 43, the negative electrode plate 42, and the separator 43 is supplied at a constant speed toward the taping device 60, and the taping device 60 is a virtual upper and lower surfaces of the supplied stack. The tape 45 is attached along the cutting line p. The tape 45 is made of an elastic material, and the tape material is preferably made of polyethylene, polypropylene, teflon or ABS. In addition, the width of the tape is preferably 1mm-10mm.

Next, as shown in FIG. 7 as a fourth step, the first step was fabricated on the upper and lower sides of the separator 43-cathode plate 42-separator 43 laminated strip to which the tape 45 was attached. Each of the bipolar plate strips 41 is fed and laminated, and pressed by passing through a heated roll 50. By this process, a strip in which the positive electrode plate 41, the separator 43, the negative electrode plate 42, the separator 43, and the positive electrode plate 41 are sequentially stacked as shown in the right side of FIG. In addition, a structure in which the tape 45 is inserted at regular intervals along the cutting line p is provided between the two separators 43 and the two positive electrode plates 41.

Then, as shown in FIG. 8A as the last fifth step, the laminate strip made in the fourth step is supplied toward the cutting device 80, and the laminate strip is cut at regular intervals, thereby providing a plurality of unit cells. Make 40. At this time, the portion to be cut will be cut along the portion to which the tape 45 is attached, that is, the portion indicated by p. In the unit cell 40, the negative electrode plate 42 is positioned at the center thereof, the separator 43 is positioned at both sides of the negative electrode plate, and the positive electrode plate 41 is positioned at both sides of the separator 43, and the separator 43 is disposed. And the tape 45 is interposed between the positive electrode plate 41 and the cutting line.

With reference to FIG. 8B, the said cutting process is demonstrated in detail. Assuming that the blade of the cutting device 80 proceeds from the upper and lower sides of the laminate strip toward the center, the burr 46 generated by cutting the perforated upper and lower bipolar plates 41 first extends toward the center portion of the pole plate. At this time, the tape 45 located inside the positive plate 41 is also cut. Since the tape 45 is made of an elastic material, the end 45a of the tape 45 extends toward the center by a predetermined length during cutting. This will prevent the burr 46 from extending. When the cutting blade of the cutting device advances further toward the center of the pole plate and the cutting of the tape 45 is completed, the end portion 45a of the tape 45 is returned to its original length by its elastic force. 46) is pushed outward (in the direction of the arrow). Therefore, since the burr 46 does not extend beyond the tape 45 toward the center of the pole plate, the burr of the positive plate eventually comes into contact with the negative plate, thereby preventing the battery short circuit.

The unit cell 40 prepared by the above process is immersed in an ether solvent to extract DBP, which is a plasticizer, and the electrolyte is impregnated in the space from which the plasticizer is extracted by charging and discharging on the electrolyte solution.

Although not shown, the third step may be performed before the second step. That is, by attaching the tape 45 to the outer surfaces of the two separator strips 43 completed in FIG. 1 at regular intervals first, and then supplying the tape 45 together with the negative electrode plate 42 to compress the separator, the negative electrode plate having the tape is provided. A separator laminated body is formed. The laminate strip is laminated together with two positive electrode plates 41 and compressed to provide a bi-cell electrode having a tape interposed between the separator and the positive electrode plate. In this method, since five strips can be laminated at the same time, there is an advantage that the process can be simplified.

Figure 9 schematically shows another embodiment of a method of manufacturing a lithium ion polymer battery according to the present invention. The manufacturing method according to the present embodiment relates to the manufacturing method of the battery shown in FIGS. 3A and 3B. Since the manufacturing method of this embodiment is not essentially different from the first embodiment, a detailed description of each process is omitted. For convenience, the electrode tabs of the positive and negative electrode strip strips 41 and 42 are not shown in FIG. 9.

First, a positive plate strip 41, a negative plate strip 42, and a separator strip 43 as shown in Figs. 4A to 4B are made. The tape 45 is attached to the outside of the separator strip 43 by the taping device 60 at regular intervals. Thereafter, the positive electrode plate strip 41, the separator strip 43, and the negative electrode plate strip 42 are laminated in this order, and pressed through the roll 50. At this time, the tape 45 should be interposed between the positive electrode strip 41 and the separator strip 43 or between the separator strip 43 and the negative electrode strip 42. Then, the plurality of unit cells 400 are completed by cutting the tape attachment portion of the positive electrode plate-separator-cathode plate laminate by the cutting device 80.

As described above, the lithium ion polymer battery and the method of manufacturing the same according to the present invention have an advantage that the defective rate can be significantly reduced by preventing the battery short circuit caused by the burr generated during the battery cutting operation.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible.

Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (8)

In a lithium ion polymer battery comprising at least one unit electrode having a structure in which a positive electrode plate, a separator, and a negative electrode plate are sequentially stacked, At least one tape is inserted between at least one of the separator and the positive electrode plate and between the separator and the negative electrode plate and positioned on the electrode cutting surface of the edge of the unit electrode. A lithium ion polymer battery, characterized by preventing contact with. The method of claim 1, The unit electrode has a bi-cell structure consisting of two separators each laminated on both side surfaces of one cathode plate and two positive electrode plates each laminated on the outer surface of each separator, And the tape is inserted between the separator and the positive electrode, respectively. The method of claim 1, The material of the tape is a lithium ion polymer battery, characterized in that at least one selected from the group consisting of polyethylene, polypropylene, Teflon, ABS. The method of claim 1, And the tape is made of an elastic material. The method of claim 1, The width of the tape is a lithium ion polymer battery, characterized in that between 1mm and 10mm. The first step of making the positive electrode strip, the negative electrode strip and the separator strip, A second step of laminating and compressing the separator strips on both sides of the negative electrode strip; Attaching a tape to an outer surface of each of the compressed separator strips at a predetermined interval, wherein the interval is equal to a width of a unit electrode; A fourth step of laminating and compressing each of the positive electrode strips on the outer surface of the tape-separated separator strips; And a fifth step of cutting the strip laminate into a plurality of unit electrodes by cutting the tape attachment portion. The method of claim 6, And the third step is performed before the second step. Creating a positive electrode strip, a negative electrode strip and a separator strip; Attaching the tape to the outer surface of at least one of the positive electrode strip, the negative electrode strip, and the separator strip at regular intervals; Stacking and compressing the positive electrode strip, the separator strip, and the negative electrode strip in an order; And cutting a plurality of unit electrodes by cutting the tape attachment portion of the strip laminate.