KR20000032030A - Fabrication method of lithium polymer battery - Google Patents

Abstract

PURPOSE: A fabrication method of lithium polymer battery is provided to prevent the short-circuit in bent portions with sustaining the advantages of continuous process as such. CONSTITUTION: A fabrication method of lithium polymer battery comprises steps of: coating or fusing electrodes with constant gap on an aluminum mesh(1) and a copper mesh(5) which are dust collector; cutting the portions between the coated electrodes in constant size; inserting polymer electrolyte(3) between anodes(2) and cathodes(4); and bending the stacked electrode. The short-circuit between the anode(2) and the cathode(4) is prevented by the polymer electrolyte(3) between the anode(2) and the cathode(4).

Description

Lithium Polymer Battery Manufacturing Method

The present invention relates to a method for producing a lithium polymer battery, and more particularly, to a method for producing a lithium polymer battery using PVdF (polyvinylidene fluoride) polymer film.

With the development of portable small electronic devices and the rapid spread of electric power sources, the capacity and light weight of electric power sources are accelerating. Most of small electronic devices use Ni-Cd, Ni-MH, Li-rechargeable batteries. Ni-Cd, Ni-MH batteries have high energy density per volume, but because the batteries themselves are heavy, household electronic devices such as shavers and telephones I use it a lot. On the other hand, a lithium secondary battery has a high volume or weight energy density, and has a high energy density compared to other secondary batteries, which is very useful as a portable power source and is currently used in most portable telephones.

Lithium secondary batteries are classified into lithium ion batteries and lithium polymer batteries by battery configuration. Lithium-ion battery is inserted into a can of a polymer film having micropores between a positive electrode and a negative electrode, rolled like a roll cake, and put an electrolyte into a battery. An organic electrolyte solution containing lithium salt is added to the polymer film to manufacture a battery, and the electrolyte solution serves as a medium for delivering lithium ions. Inside the cell, lithium ions move between the positive and negative electrodes, while the current flows outside. At this time, since lithium ions play a role of ion conduction between the positive electrode and the negative electrode, it is called a lithium ion battery.

The electrode body of a lithium ion battery is wound like a roll cake and put into a cylindrical can to make a cylindrical battery, or by pressing the wound electrode body into a square can to make a square battery. Lithium-ion batteries are classified into rectangular batteries and cylindrical batteries according to the shape of the batteries.

Lithium ion batteries are used by impregnating an organic electrolyte solution in a microporous membrane as an electrolyte, whereas lithium polymer batteries have a polymer film as an electrolyte and a lithium salt, which is a medium of ions in the polymer electrolyte, dissolves in the ion conducting role. . Lithium-ion battery using liquid electrolyte has risk of ignition and explosiveness of organic electrolyte and there is possibility of leakage, so lithium polymer battery using polymer electrolyte uses small amount of liquid electrolyte in polymer or polymer itself. Since it serves as an electrolyte, it is excellent in safety and can be freely manufactured in shape. Since there are few organic electrolytes used in a battery, it is possible to manufacture a battery using a polymeric packaging agent.

In a lithium polymer battery, it is impossible to manufacture an electrode body composed of a positive electrode / electrolyte / negative electrode in the form of a roll cake like a lithium ion battery. That is, in the lithium polymer battery, since the polymer electrolyte is thermally fused or cast to the positive electrode and the negative electrode, it is difficult to wind the positive / electrolyte / negative electrode, it is difficult to wind it tightly, and the positive electrode and the negative electrode touch each other and short-circuit after winding. In many cases.

Typically, a lithium polymer battery is prepared as shown in FIGS. 7 and 8.

FIG. 7 illustrates a method of manufacturing a lithium polymer battery by bending an electrode body stacked in a cathode / electrolyte / cathode and stacking a plurality of layers, and FIG. 8 illustrates a cathode (1) / electrolyte (3) / cathode. It is shown that the electrode body composed of (5) to be punched to a certain size to be manufactured in a multi-ply overlapping form.

In the battery of FIG. 7, the positive electrode 2 is thermally fused to an aluminum mesh 1 as a current collector, and the negative electrode 4 is thermally fused to a copper mesh 5 as a current collector to prepare an electrode. A constant pressure and heat are applied to the PVdF electrolyte 3 between the and the cathode. An electrode composed of three layers of the positive electrode 1, the electrolyte 2, and the negative electrode 3 is folded to form a battery. In the battery fabricated by folding the electrode body several times as shown in FIG. In addition, the thickness of the positive electrode and the negative electrode is about 250 to 300㎛, the electrolyte is between 50 to 70㎛. Since the thickness of the heat-sealed electrode body is about 550 to 670 μm, it is very difficult to fold the electrode, and cracks occur in the folded electrode, and there are many side reactions that adversely affect various battery performances in the cracked portion. . In addition, there is a high possibility that the positive electrode and the negative electrode may collapse and short-circuit the electrolyte.

The battery configuration of FIG. 8 is a method of manufacturing by stacking a plurality of electrode bodies punched to a constant size. After preparing the positive electrode and the negative electrode as shown in Figure 7 by inserting a PVdF electrolyte to heat fusion to prepare an electrode body. However, although FIG. 7 is more productive than FIG. 8, there are disadvantages in the manufacturing method of FIGS. 7 and 8 because of the above-mentioned disadvantages.

It is an object of the present invention to provide a method for producing a lithium polymer battery that can prevent a short circuit in the folded portion while maintaining the advantages of the continuous process as shown in FIG.

1 is an electrode heat-sealed at regular intervals the electrode cut to a constant size.

The upper part is an anode electrode and the lower part is a cathode electrode.

2 is a view in which a portion of a heat-sealed positive electrode and a negative electrode electrode is not heat-sealed to a predetermined size, and a PVdF polymer electrolyte is inserted between the positive electrode and the negative electrode.

The upper represents an anode, the middle represents an electrolyte, and the lower represents an anode.

The positions of the positive electrode and the negative electrode may be changed.

3 is a plan view of a cell in which an anode / electrolyte / cathode electrode is fused.

4. It is sectional drawing before the thermal welding of an anode / electrolyte / cathode.

5. The battery produced by folding in accordance with the present invention, before bending.

6. The battery produced by folding by this invention is shown after bending.

7. It is a conventional method of manufacturing a lithium polymer secondary battery by folding an electrode body.

8. A battery manufactured by stacking a plurality of electrode bodies cut to a constant size.

1 -------- anode collector (aluminum mesh) 2 --------- anode

3 -------- Electrolyte / Separator 4 --------- Cathode Electrode

5 -------- Cathode Current Collector (Copper Mesh)

As shown in FIG. 1, the electrode is formed by thermally bonding an electrode on an aluminum mesh 1 and a copper mesh 5 as current collectors. Electrodes are prepared by spacing at regular intervals and sizes, or by coating electrode active materials on a current collector at predetermined sizes and intervals.

The fused or coated electrode is cut out by punching a current collector into a predetermined size between the electrode and the electrode. The upper part of FIG. 2 is an anode electrode thermally fused at regular intervals, and the middle part of FIG. 2 is a PVdF electrolyte 3 interposed between the anode and the cathode. The lower part of FIG. 2 is prepared by punching like the upper part of FIG. However, since the positive electrode and the negative electrode are laminated, the positive electrode and the negative electrode current collector are reversely processed, cut out, and stacked alternately to prevent the short circuit in the portions 1 and 5 without the electrodes. The polymer electrolyte 3 is slightly larger than the size of the positive electrode and the negative electrode to prevent a short circuit at the end between the positive electrode and the negative electrode. In the stacking of the positive electrode 2 and the negative electrode 4, the battery may be manufactured by directly stacking the non-electrode portion without cutting it to a certain size, and there is a possibility of a short circuit because there is an electrolyte 3 between the positive electrode and the negative electrode. There is no FIG. 3 is a plan view of a battery cell in which the positive electrode 1, the electrolyte solution 3, and the negative electrode 5 are heat-sealed, and FIG. 4 is a cross-sectional view of the heat-sealed battery divided by an electrode and an electrolyte. Lay the anode and cathode in the same position. 5 shows an electrode body in which an anode and a cathode are folded. The bent portions of the stacked electrodes have no electrodes 2 and 4 and the positive electrode collector 1 and the negative electrode collector 5 are connected to different positions. The stacked batteries are stacked in the order of anode / cathode: cathode / anode: anode / cathode. That is, there is no possibility of a short circuit because the same electrodes touch each other.

According to the present invention, it is possible to easily solve a continuous process part that was difficult in manufacturing a lithium polymer secondary battery. There are many occurrences of cracks and short circuits in the part where the electrode is folded as in FIG. 7, but in the battery of FIGS. 1 to 6 according to the present invention, since the electrode is not attached to the folded part, the electrode can be easily folded. Therefore, short circuit and crack of an electrode can be prevented. In addition, as in the manufacture of a plurality of electrodes laminated as shown in FIG. 8, it does not take much time and a continuous process is possible. Therefore, according to the present invention, the continuous process of the lithium polymer secondary battery can be made like a lithium ion battery. Thermal fusion of electrodes at a certain size and location can be easily solved through an automated process.

Claims (1)

In the lithium polymer battery manufacturing method, the electrode of the positive electrode and the negative electrode at a predetermined size and a predetermined interval heat-sealed on the aluminum mesh and copper mesh of the current collector, and then the electrode body is not fused by folding the battery body several times to manufacture A lithium polymer battery manufacturing method.