Method for manufacturing secondary battery

Abstract

The present invention relates to a method for manufacturing a square secondary battery in which a guide pin is inserted into a winding core, the winding core is stretched to the left and right by detecting and rotating an electrode plate, the guide pin is removed in a state in which the winding core is extruded and heated by a first press, and then the winding core is extruded and heated by a second press, thereby manufacturing a square battery capable of preventing wrinkles on a diaphragm. According to the invention, the roll core is wound into a circle, the two guide pins are inserted, then the guide pins extend leftwards and rightwards through step-by-step rotation and vibration of the guide pins, so that the roll is wound into an oval shape, a first press is used for extruding up and down and heating by ultrasonic waves at the same time, so that the middle part of the roll core forms a rectangle, and the two ends of the roll core form a round shape at the same time; and then removing the guide pins inserted in the circles on the two sides, extruding the roll core from the top and bottom by using a second press machine, and heating by using ultrasonic waves at the same time, thereby completing the square battery without wrinkles on the diaphragm.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a square secondary battery, specifically, a guide pin is inserted into a winding core, the winding core is stretched to the left and right through electrode sheet (Tap) detection and step-by-step rotational vibration, the guide pin is removed while being squeezed and heated by a first press, and the winding core is squeezed and heated again by a second press, thereby manufacturing a square battery that can prevent wrinkles on the diaphragm. Background Art

[0002] Generally, there are two methods for storing electrical energy. One is the electrolytic method that uses the redox reaction of ions to store electrical energy as chemical energy. The other is the electrostatic method that uses the polarization phenomenon between two electrodes to store electrical energy as electrical energy itself.

[0003] Secondary batteries such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium-ion polymer batteries can be repeatedly charged and discharged through the reversible conversion between chemical energy and electrical energy. They are the first electrolytic storage method that can be reused, while the second electrostatic storage method uses the polarization phenomenon between the two plates to repeatedly charge and discharge the capacitor for reuse.

[0004] Electrolytic batteries are batteries that are repeatedly charged and discharged through a reversible redox reaction between electrical energy and chemical energy. They can store large amounts of energy due to their high energy density. However, when electrical energy and chemical energy are converted to each other, energy conversion loss occurs, and heat is generated, posing a risk of fire and explosion. They cannot be charged or charged with large amounts of energy in a short period of time. Therefore, not only does the charging time become longer, charging becomes difficult, and discharge performance deteriorates, but they also have a short lifespan and emit pollutants.

[0005] Recently, as the focus on energy storage technology has increased, its application areas have gradually expanded to mobile phones, camcorders, laptop computers, and even electric vehicles, and efforts in the research and development of electrochemical components related to this have gradually become concrete. Electrochemical components are the most popular field in this regard, and the development of rechargeable and dischargeable secondary batteries has become the focus of attention. In order to develop such batteries, research and development aimed at improving capacity density and specific energy is currently being carried out.

[0006] Among the secondary batteries currently in use, the lithium secondary battery developed in the early 1990s has attracted much attention due to its advantages of high operating voltage and high energy density compared to conventional batteries such as Ni-MH, Ni-Cd, and sulfuric acid-lead batteries that use aqueous electrolytes. However, this type of lithium-ion battery uses an organic electrolyte, so it has safety issues such as easy fire and explosion, and has the disadvantage of a complicated manufacturing process.

[0007] Currently, lithium-ion polymer batteries are regarded as one of the new generation of batteries by improving these weaknesses of lithium-ion batteries. However, so far, the battery capacity is lower than that of lithium-ion batteries, especially the discharge capacity is insufficient in low temperature environments, so there is an urgent need to improve this.

[0008] As for the safety characteristics of the electrochemical element as described above, the main consideration is that the electrochemical element should not harm the user in the event of misoperation. Therefore, from the perspective of safety standards, fire and smoke in the electrochemical element are strictly regulated.

[0009] Regarding the safety characteristics of electrochemical components, there is a high possibility of explosion when the electrochemical component overheats and thermal runaway occurs or the diaphragm is penetrated, especially the polyolefin porous substrate used as the diaphragm of the electrochemical component. Due to the material properties and the characteristics of the manufacturing process including stretching, it exhibits great thermal shrinkage at temperatures above 100 degrees, thereby causing a short circuit between the positive and negative electrodes.

[0010] In the manufacturing process of the diaphragm, an organic-inorganic porous coating is formed on the surface of the membrane. In order to be used in the manufacturing process of the electrode assembly for lithium secondary batteries, the diaphragm needs to be wound onto a roll-shaped rewinder, and in order to ensure the smooth winding operation, a guide roller is set on the travel path of the diaphragm so that the diaphragm must pass through the guide roller before being wound on the reel.

[0011] However, since this separator is a very thin film with a thickness of 10 to 50 μm, wrinkles are easily generated when the separator contacts and moves along the guide roller. As described above, when wrinkles occur on the separator, the amount wound on the roll will decrease, and the yield will also decrease accordingly.

[0012] In addition, the problem that existed in the past is that winding may have an adverse effect on the electrical properties and overall performance of the product.

[0013] [Prior technical literature]

[0014] [Patent Literature]

[0015] Patent application number 10-2007-7004325;

[0016] Patent application number 10-2019-0032322. Summary of the invention

[0017] Technical issues

[0018] The present invention is to solve the above-mentioned problems that have existed in the past. According to the present invention, in order to prevent wrinkles from occurring during the winding process of a separator forming a porous organic-inorganic coating, a square secondary battery manufacturing method using guide pins and a press machine to manufacture the membrane is provided.

[0019] Technical Solution

[0020] To achieve the above-mentioned purpose, the solution adopted by the present invention is preferably, including: a first step of rolling the core into a circle; a second step of inserting two guide pins into the core; a third step of expanding the guide pins to the left and right through the step-by-step rotation and vibration of the guide pins, so that the winding becomes an elliptical shape; a fourth step of using a first press to extrude up and down and heat with ultrasound to make the middle part of the core into a rectangle while the two ends form a circular shape; a fifth step of removing the guide pins inserted into the circles on both sides in the fourth step when the core is stretched by the up and down extrusion of the first press and by ultrasonic heating; a sixth step of using a second press to extrude up and down and heat the core with ultrasound when the guide pins are completely removed in the fifth step, thereby completing a square battery without wrinkles on the membrane.

[0021] Preferably, the first press and the second press implement ultrasonic heating or heating during extrusion.

[0022] Preferably, when the winding core is stretched to the left and right by the guide pins, the winding core is stretched to a certain extent by the step-by-step rotational vibration according to the inclination.

[0023] Beneficial Effects

[0024] The beneficial effect of the present invention is that a guide pin is inserted into the core, which is detected and rotated to stretch left and right through the electrode sheet, and the guide pin is removed after being squeezed and heated by a first press, and then the core is re-extruded and heated by a second press wider than the first press, thereby not only preventing the diaphragm from wrinkling, but also arranging the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram showing the manufacturing process of the square secondary battery manufacturing method of the present invention.

[0026]

Explanation of symbols

[0027] 1: winding core; 2: guide pin;

[0028] 3: First press; 4: Second press. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Figure 1 It is a schematic diagram showing the sequence of the square secondary battery manufacturing method of the present invention. As shown in the figure, generally speaking, from the classification of lithium-ion batteries (batteries), according to the packaging materials and shapes, they are divided into three battery forms, namely cylindrical, square, and soft pack.

[0031] According to the assembled shape of positive electrode, negative electrode and separator, it can be classified into winding and stacking according to the shape of jelly roll. The electrode process and formation process will not be greatly affected by the shape of jelly roll, but the assembly process is based on the assembly method of jelly roll, and the equipment will be different.

[0032] The present invention relates to a method for manufacturing a square secondary battery in the secondary battery form, such as Figure 1 As shown, first, when the winding core 1 is rolled into a circular shape as shown in (A), two guide pins 2 are inserted into the winding core 1 as shown in (B).

[0033] As described above, if the guide pin 2 is inserted into the winding core 1, and the guide pin 2 is stretched and expanded to the left and right through the rotation and vibration of the guide pin 2, the winding 1 is arranged into an elliptical shape as shown in (C), and when the winding core 1 is pulled to the left and right by the guide pin 2, the winding core 1 is stretched by the inclination of the guide pin 2, that is, the step-by-step rotation and vibration.

[0034] As shown in (C), when the winding core 1 becomes an elliptical state, as shown in (D), the first press machine 3 is used to press up and down and heat with ultrasound, whereby the winding core 1 is stretched, and the middle part forms a rectangular shape while the two ends are deformed into a circular shape. At this time, the guide pin 2 remains inserted in the center of the two sides of the circle.

[0035] Furthermore, as shown in (D), in a state where the winding core 1 is stretched by the upper and lower pressing and ultrasonic heating of the first press machine 3, as shown in (E), the guide pins 2 inserted into the circles on both sides are completely removed.

[0036] As shown in (E), when all the guide pins 2 are removed, the core 1 is pressed from the top and bottom by the second press machine 4 while being heated by ultrasonic waves, and the square battery is completed.

[0037] When a square secondary battery is manufactured by the above-described process, the negative electrode and positive electrode films forming the winding core 1 are pressed and heated by the first and second press machines 3 and 4 to prevent the films from wrinkling.

[0038] The present invention described above is not limited to the embodiments. Obviously, it goes without saying that ordinary technicians in the technical field to which the present invention belongs can effectively apply it through various embodiments, but this does not make the essence of the corresponding technical solution deviate from the scope of the technical solution described in each embodiment of the present invention.

Claims

1. A method for manufacturing a square secondary battery, characterized in that: include: The first step is to roll the roll core (1) into a circular shape; The second step is to insert two guide pins (2) into the winding core (1); The third step is to expand the guide pin (2) to the left and right by rotating and vibrating the guide pin (2) in steps, so that the winding (1) becomes an ellipse; The fourth step is to use the first press machine (3) to press and heat the roll core (1) from top to bottom, so that the middle part of the roll core (1) becomes a rectangle and the two ends become round; The fifth step is to remove the guide pins (2) inserted into the circles on both sides while the winding core (1) is stretched by the upper and lower extrusions of the first press (3) in the fourth step; In the sixth step, after all the guide pins (2) are removed in the fifth step, the winding core (1) is pressed upward and downward using a second press (4), thereby completing a square battery without wrinkles on the film.

2. The method for manufacturing a square secondary battery according to claim 1, characterized in that: The second press (4) is formed to have a size capable of pressing the remaining portion of the winding core (1) except for the semicircular portions at both ends.

3. The method for manufacturing a square secondary battery according to claim 1 or claim 2, characterized in that: The second press machine (4) is formed to be wider in left and right directions than the first press machine (3).

4. The method for manufacturing a square secondary battery according to claim 1, characterized in that: The first press (3) and the second press (4) implement ultrasonic heating or heating during extrusion.

Images