Secondary battery and method for manufacturing the same

Abstract

The present invention relates to a method for manufacturing a secondary battery, the method including an activation process of performing charge / discharge and aging, the method further including: a step of providing a first battery cell and a second battery cell, each of the first battery cell and the second battery cell having a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag; a step of stacking the first battery cell and the second battery cell; and a step of bonding the positive electrode leads of the first battery cell and the second battery cell to each other and bonding the negative electrode leads of the first battery cell and the second battery cell to each other, wherein before the step of providing the first battery cell and the second battery cell, the activation process is performed separately on each of the first battery cell and the second battery cell. In the present invention having the above technical features, since each of the first battery cell and the second battery cell is stacked and bonded after the activation process, a conventional small and medium-sized charger / discharger can be used.

Description

Technical Field

[0001] The present invention relates to a secondary battery requiring high energy density and a method of manufacturing the same, and more particularly, to a secondary battery activated by using a small charger according to the prior art and a method of manufacturing the same. Background Art

[0002] Recently, the demand for secondary batteries as energy sources is increasing rapidly. Such secondary batteries can be used in the form of a single battery cell or in the form of a battery module in which a plurality of battery cells are electrically connected to each other according to the type of external device. For example, a small device such as a mobile phone uses the output and capacity of one battery cell to run for a predetermined time. On the other hand, medium or large devices such as notebook computers, portable DVDs, personal computers, electric vehicles, hybrid electric vehicles, etc. need to use a battery module including a large number of battery cells due to their output and capacity problems.

[0003] This secondary battery is manufactured by a process of assembling battery cells and a process of activating the battery. Here, the battery activation process is generally performed by repeatedly applying a current to the battery cell as a target object to be charged / discharged; or repeatedly discharging the battery cell by means of a charging / discharging device including a positive and negative electrode contact device, and then aging it for a predetermined time. The charging / discharging device of the secondary battery includes: a bracket to which the battery cell is fixed; and a contact device, which is connected to the positive and negative electrodes of the battery cell fixed to the bracket for charging / discharging.

[0004] In the case of mounting the secondary battery on an energy storage system (ESS), the secondary battery has a large thickness to increase energy density.

[0005] like Figure 1 As shown, it shows a state in which two electrode assemblies are installed in one bag to manufacture a high-capacity battery with increased thickness and simplified process, and the electrode assemblies 2 are respectively arranged on both sides to form two arrangement portions ( Figure 1 In a bag 1 (a portion recessed to accommodate the electrode assembly), the center 1b of the accommodation portion 1a is folded to increase the thickness.

[0006] However, this structure has the following disadvantages in view of the following problems: when the number of dual cells constituting the electrode assembly increases, the folding process becomes more complicated and the existing device needs to be modified. On the other hand, there is a problem of not using the existing charging / discharging device. For example, in order to fix and place on the bracket of the charging / discharging device due to the increase in thickness, the device needs to be adjusted, and the sliding position of the contact device must be modified. In addition, because the capacity increases, there is a problem that it is difficult to smoothly perform the activation process using the charging capacity of the existing charging / discharging device. Summary of the invention

[0007] Technical issues

[0008] Therefore, a main object of the present invention is to provide a method for manufacturing a secondary battery including two (or more) electrode assemblies to increase capacity so as to perform an activation process by using an existing charging / discharging device.

[0009] Technical Solutions

[0010] The present invention for achieving the above object provides a secondary battery and a method for manufacturing the secondary battery.

[0011] According to a method for manufacturing a secondary battery of the present invention, the method includes an activation process for charging / discharging and aging, the method including: a step of providing a first battery cell and a second battery cell, each of the first battery cell and the second battery cell having a structure in which an electrode assembly is embedded in a bag and a negative lead and a positive lead protrude to the outside of the bag; a step of stacking the first battery cell and the second battery cell; and a step of combining the positive leads of the first battery cell and the second battery cell with each other and combining the negative leads of the first battery cell and the second battery cell with each other, wherein, before the step of providing the first battery cell and the second battery cell, the activation process of each of the first battery cell and the second battery cell is performed separately.

[0012] The bonding between the negative electrode leads and the bonding between the positive electrode leads may be performed by welding.

[0013] Each of the bag of the first battery cell and the bag of the second battery cell may have a shape formed with two planes parallel to each other, and in the step of stacking the first battery cell and the second battery cell, one of the planes of the bag of the first battery cell and one of the planes of the bag of the second battery cell may be stacked to contact each other.

[0014] Here, the first and second cells are stacked so that the positive leads of the first and second cells point in the same direction (ie, parallel to each other) and the negative leads of the first and second cells point in the same direction (ie, parallel to each other).

[0015] Furthermore, the method may further include the step of attaching a tape between the bag of the first battery cell and the bag of the second battery cell, the tape allowing the first battery cell and the second battery cell to be bonded to each other. The tape may include an insulating tape having electrical insulation.

[0016] Alternatively, the method may further include the step of applying an adhesive between the pouch of the first battery cell and the pouch of the second battery cell, the adhesive allowing the first battery cell and the second battery cell to be adhered to each other.

[0017] Here, the pouch of the first battery cell and the pouch of the second battery cell may have the same shape and size.

[0018] In addition, in the manufacturing method according to the present invention, a third battery cell may be additionally stacked. That is, the method may further include: a step of additionally providing a third battery cell having a structure in which a battery assembly is embedded in a bag and a negative lead and a positive lead protrude to the outside of the bag; a step of stacking the third battery cell on the second battery cell coupled to the first battery cell so that the second battery cell is arranged between the first battery cell and the third battery cell; and a step of combining the positive leads of the second battery cell and the third battery cell with each other, and combining the negative leads of the second battery cell and the third battery cell with each other, wherein, before the step of additionally providing a third battery cell, the third battery cell may be subjected to a separate activation process in which the charging / discharging and the aging are performed.

[0019] Here, the bag of the third battery cell may have a shape capable of being bonded to the bag of the first battery cell and the bag of the second battery cell. The method may further include the step of pasting a tape between the bag of the second battery cell and the bag of the third battery cell, the tape allowing the second battery cell and the third battery cell to be bonded to each other. Alternatively, the method may further include the step of applying an adhesive between the bag of the second battery cell and the bag of the third battery cell, the adhesive allowing the second battery cell and the third battery cell to be bonded to each other.

[0020] In addition, a secondary battery manufactured by performing an activation treatment of charge / discharge and aging, the secondary battery including: a first battery cell, the first battery cell undergoing the activation treatment and having a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag; and a second battery cell, the second battery cell having a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag, and the second battery cell undergoing the activation treatment, wherein the second battery cell is stacked on the first battery cell, and the negative electrode lead and the positive electrode lead are respectively bonded to the negative electrode lead and the positive electrode lead of the first battery cell, thereby being connected in parallel to each other, wherein surfaces of the first battery cell and the second battery cell stacked to contact each other are bonded to each other.

[0021] Here, a third battery cell may be added. That is, the secondary battery may further include a third battery cell that is subjected to the activation treatment and has a structure in which the electrode assembly is embedded in a bag and the negative electrode lead and the positive electrode lead protrude to the outside of the bag, wherein the third battery cell is stacked on the second battery cell at a relative position to the first battery cell, and the negative electrode lead and the positive electrode lead of the third battery cell are respectively bonded to the negative electrode lead and the positive electrode lead of each of the first battery cell and the second battery cell so as to be connected in parallel with each other, wherein the surfaces of the third battery cell and the second battery cell stacked in contact with each other are bonded to each other.

[0022] The bonding between the first battery cell and the second battery cell may be performed by means of an adhesive tape laminated between the first battery cell and the second battery cell.

[0023] Beneficial Effects

[0024] According to the present invention having the above technical features, since the first battery cell and the second battery cell are stacked and combined after being subjected to the activation process, a small and medium-sized charging / discharging device according to the related art can be used.

[0025] Since the first battery cell and the second battery cell are connected in parallel to each other, the charging capacity can be increased, and the third battery cell can be added to further increase the charging capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a perspective view of a secondary battery in which two electrode assemblies are mounted in one pouch.

[0027] Figure 2a is a perspective view showing a state in which an electrode assembly is embedded in a pouch of each of a first battery cell and a second battery cell.

[0028] Figure 2b is a perspective view showing a state before a first battery cell is mounted in the charging / discharging device.

[0029] Figure 2c 1 is a perspective view showing the state before (lower figure) and after (upper figure) the first battery cell and the second battery cell are stacked.

[0030] Figure 2d It is a plan view of the first battery cell and the second battery cell, and is a side view showing a state in which the first battery cell and the second battery cell are stacked.

[0031] Figure 3 It is a perspective view showing a state before the first battery cell, the second battery cell, and the third battery cell are stacked.

[0032] Figure 4 is a flowchart showing a manufacturing method according to a first embodiment of the present invention. DETAILED DESCRIPTION

[0033] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the technical ideas of the present invention. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments described herein.

[0034] In order to clearly illustrate the present invention, parts irrelevant to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

[0035] In addition, the terms or words used in the specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and interpret his invention.

[0036] The present invention relates to a secondary battery in which two (or more) secondary batteries are provided to increase capacity and an activation process is performed by using an existing charging / discharging device. Hereinafter, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

[0037] First embodiment

[0038] A method of manufacturing a secondary battery using an existing small and medium-sized charging / discharging device and increasing capacity will be described according to a first embodiment of the present invention.

[0039] like Figure 4 , which shows a flowchart of a manufacturing method according to a first embodiment, the manufacturing method according to the embodiment includes: providing a first battery cell and a second battery cell; stacking the first battery cell and the second battery cell; and combining the leads (positive electrode lead and negative electrode lead) of the first battery cell and the second battery cell with each other. Each of the first battery cell and the second battery cell is provided in a state where an activation process is performed separately.

[0040] That is, as shown in the state where the electrode assembly is embedded in the bag of each of the first battery cell and the second battery cell Figure 2a As shown, each of the first battery cell 10 and the second battery cell 20 is provided in a state where the electrode assemblies 12 and 22 and the electrolyte (not shown) are embedded in the pouches 11 and 21, and an activation process is performed.

[0041] In the first battery cell 10 and the second battery cell 20, each of the positive electrode leads 12a and 22a and the negative electrode leads 12b and 22b protrude to the outside of the bags 11 and 21, and each of the bags 11 and 21 is manufactured to be sealed along its edge in a state where each of the electrode assemblies 12 and 22 is embedded in the seating portion 11a. Also, as shown in FIG. 1 , the state before the first battery cell 10 is installed in the charging / discharging device 20 is shown. Figure 2b As shown, the activation process is performed with the aid of a small or medium-sized charging / discharging device 30 used in the prior art.

[0042] The charging / discharging device 30 includes: a bracket 31 on which a battery cell (a first battery cell or a second battery cell) is placed and fixed; and a contact device 32, which is in electrical contact with the positive electrode leads 12a and 22a and the negative electrode leads 12b and 22b of the electrode assembly. The charging / discharging device 30 is configured to apply current to the placed battery cell or discharge current. The battery cell repeatedly charged and discharged by the charging / discharging device 30 is removed from the bracket and then aged in a space maintained at a predetermined temperature and humidity, thereby completing the activation process.

[0043] The first cell 10 and the second cell 20, which have been activated separately, are stacked. That is, as shown in the figure before (lower figure) and after (upper figure) the first cell and the second cell are stacked Figure 2c As shown, the bag 11 of the first battery cell 10 and the bag 21 of the second battery cell 20 have the same shape, and the two bags respectively have two planes parallel to each other. In the step of stacking the first battery cell 10 and the second battery cell 20, one of the planes of the bag 11 of the first battery cell 10 and one of the planes of the bag 21 of the second battery cell 20 are stacked to contact each other.

[0044] Here, one surface of the bag 11 with a larger area and one surface of the bag 21 with a larger area are bonded to each other by using the tape 40 or an adhesive. The positive electrode leads 12a and 22a and the negative electrode leads 12b and 22b may be stacked to face the same direction so that the first battery cell 10 and the second battery cell 20 are connected to each other in parallel.

[0045] Before stacking the first battery cell 10 and the second battery cell 20, a step of attaching a tape 40 between the bag 11 of the first battery cell 10 and the bag 21 of the second battery cell 20, or a step of applying an adhesive between the bag 21 of the first battery cell 10 and the bag 21 of the second battery cell 20 may be performed. Here, the tape 40 may be a double-sided tape, and preferably, each of the tape 40 and the adhesive is made of a material having electrical insulation to prevent a short circuit.

[0046] Referring to a plan view showing a first battery cell and a second battery cell and a side view showing a stacked first battery cell and a second battery cell Figure 2dIn a state where the bag 11 of the first battery cell 10 and the bag 21 of the second battery cell 20 are combined with each other, the positive electrode leads 12a and 22a can be combined with each other, and the negative electrode leads 12b and 22b can be combined with each other, so that the first battery cell 10 and the second battery cell 20 are connected to each other in parallel.

[0047] Here, bonding between the negative electrode leads and bonding between the positive electrode leads may be performed by welding using ultrasonic waves or lasers.

[0048] Second embodiment

[0049] Furthermore, in the manufacturing method according to the present invention, a process of stacking the third battery cells 50 is additionally performed.

[0050] In this embodiment, in addition to the steps according to the first embodiment, a step of additionally providing and laminating the third battery cell 50 is performed. That is, in addition to the steps of the manufacturing method according to the first embodiment, this embodiment further includes the following steps: a step of additionally providing the third battery cell 50 having a structure in which the electrode assembly is embedded in the bag and the negative electrode lead and the positive electrode lead protrude to the outside of the bag; a step of laminating the third battery cell 50 on the second battery cell 20 coupled to the first battery cell 10 so that the second battery cell 20 is arranged between the first battery cell 10 and the third battery cell 50; and a step of bonding the positive electrode leads of the second battery cell 20 and the third battery cell 50 to each other and bonding the negative electrode leads of the second battery cell 20 and the third battery cell 50 to each other. Similarly, the third battery cell 50 is provided after separately performing an activation process in which charging / discharging and aging are performed.

[0051] The bag of the third battery cell 50 is not particularly limited as long as the bag has a shape that can be bonded to the bag 11 of the first battery cell 10 and the bag 21 of the second battery cell 20. Referring to FIG. Figure 3 Preferably, the areas of both surfaces of the second battery cell 20 arranged between the first battery cell and the third battery cell are the same as the areas of the wide surfaces of the bags of each of the first battery cell 10 and the third battery cell 50 , so that both surfaces of the second battery cell are bonded.

[0052] Similarly, the third battery cell 50 is bonded to the second battery cell 20 by means of a tape or an adhesive. The negative electrode lead and the positive electrode lead of the third battery cell 50 are respectively bonded to the negative electrode lead and the positive electrode lead of each of the first and second battery cells, thereby being connected in parallel to each other.

[0053] Third embodiment

[0054] This embodiment provides a secondary battery manufactured by a manufacturing method according to each of the first and second embodiments. The secondary battery provided in the present embodiment may be a secondary battery manufactured by undergoing an activation process in which charging / discharging and aging are performed. The secondary battery has a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag, and includes a first battery cell 10 and a second battery cell 20, and the first battery cell 10 and the second battery cell 20 are subjected to an activation process. In addition, the negative electrode lead and the positive electrode lead of the first battery cell 10 and the second battery cell 20 are combined with each other, thereby being connected in parallel to each other, so that the contact surfaces therebetween are bonded to each other.

[0055] In addition, the manufacturing method according to the second embodiment can be applied to add a third battery cell 50 in addition to the first battery cell 10 and the second battery cell 20. That is, the third battery cell 50 can be additionally bonded to the surface of the second battery cell opposite to the bonding first battery cell 10. Here, the first battery cell 10, the second battery cell 20, and the third battery cell 50 can all be bonded in a state of undergoing an activation process. A tape can be pasted between the first battery cell 10 and the second battery cell 20 and between the second battery cell 20 and the third battery cell 50, or an adhesive can be applied between the first battery cell 10 and the second battery cell 20 and between the second battery cell 20 and the third battery cell 50 to allow the first battery cell 10, the second battery cell 20, and the third battery cell 50 to be bonded to each other. Here, the first battery cell 10, the second battery cell 20, and the third battery cell 50 can be connected in parallel to each other. In addition, in addition to the third battery cell, the fourth battery cell and the fifth battery cell can be stacked separately.

[0056] According to the present invention having the above technical features, since the first battery cell 10 and the second battery cell 20 are stacked and combined after being subjected to an activation process, a small and medium-sized charging / discharging device according to the related art can be utilized.

[0057] Since the first battery cell 10 and the second battery cell 20 are connected to each other in parallel, the charge capacity may be increased, and the third battery cell and the fourth battery cell may be sequentially added so that the charge capacity is further increased.

[0058] While embodiments of the present invention have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

[0059] CROSS-REFERENCE TO RELATED APPLICATIONS

[0060] This application claims the benefit of priority from Korean Patent Application No. 10-2019-0003324, filed on January 10, 2019, which is hereby incorporated by reference in its entirety.

Claims

1. A method for manufacturing a secondary battery, the method comprising an activation process of performing charge / discharge and aging in the same charge / discharge device, the method comprising: providing a first battery cell and a second battery cell, each of the first battery cell and the second battery cell having a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag; A step of stacking the first battery core and the second battery core; as well as The steps of bonding the positive electrode leads of the first battery cell and the second battery cell to each other and bonding the negative electrode leads of the first battery cell and the second battery cell to each other, Before providing the first battery cell and the second battery cell, the activation process of each of the first battery cell and the second battery cell is performed separately. The method further comprises: a step of additionally providing a third battery cell having a structure in which a battery assembly is embedded in a pouch and a negative electrode lead and a positive electrode lead protrude to the outside of the pouch; The step of stacking the third battery cell on the second battery cell coupled to the first battery cell such that the second battery cell is arranged between the first battery cell and the third battery cell; and The steps of combining the positive electrode leads of the second battery cell and the third battery cell with each other, and combining the negative electrode leads of the second battery cell and the third battery cell with each other, Before the step of additionally providing the third battery cell, the third battery cell is subjected to a separate activation process, in which the charging / discharging and the aging are performed, wherein each of the bag of the first battery cell and the bag of the third battery cell has two planes parallel to each other, one of the two planes is a narrow surface with a relatively narrow area, and the other plane is a wide surface with a relatively wide area, and The area of ​​both surfaces of the second battery cell disposed between the first battery cell and the third battery cell is the same as the area of ​​the wide surface of the bag of each of the first battery cell and the third battery cell, so that both surfaces of the second battery cell are bonded.

2. The method according to claim 1, wherein: The bonding between the negative electrode leads and the bonding between the positive electrode leads are performed by welding.

3. The method according to claim 2, wherein: Each of the pouch of the first battery cell and the pouch of the second battery cell has a shape formed with two planes parallel to each other; and In the step of stacking the first battery cell and the second battery cell, one of the flat surfaces of the pouch of the first battery cell and one of the flat surfaces of the pouch of the second battery cell are stacked to contact each other.

4. The method according to claim 3, wherein: The first battery cell and the second battery cell are stacked such that the positive electrode leads of the first battery cell and the second battery cell point to the same direction, and the negative electrode leads of the first battery cell and the second battery cell point to the same direction. 5 . The method according to claim 1 , further comprising the step of sticking a tape between the pouch of the first battery cell and the pouch of the second battery cell, the tape allowing the first battery cell and the second battery cell to be adhered to each other.

6. The method according to claim 5, wherein: The adhesive tape includes an insulating adhesive tape having electrical insulation properties. 7 . The method according to claim 1 , further comprising the step of applying an adhesive between the pouch of the first battery cell and the pouch of the second battery cell, the adhesive allowing the first battery cell and the second battery cell to be bonded to each other.

8. The method according to claim 1, wherein: The pouch of the third battery cell has a shape capable of being bonded to the pouch of the first battery cell and the pouch of the second battery cell. 9 . The method according to claim 1 , further comprising the step of sticking a tape between the pouch of the second battery cell and the pouch of the third battery cell, the tape allowing the second battery cell and the third battery cell to be adhered to each other. 10 . The method according to claim 1 , further comprising the step of applying an adhesive between the pouch of the second battery cell and the pouch of the third battery cell, the adhesive allowing the second battery cell and the third battery cell to be adhered to each other.

11. A secondary battery manufactured by an activation process of performing charge / discharge and aging in the same charge / discharge device, the secondary battery comprising: a first battery cell which is subjected to the activation process and has a structure in which an electrode assembly is embedded in a pouch and a negative electrode lead and a positive electrode lead protrude to the outside of the pouch; and a second battery cell having a structure in which an electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude outside the bag, and the second battery cell is subjected to the activation process, wherein the second battery cell is stacked on the first battery cell, and the negative electrode lead and the positive electrode lead of the second battery cell are respectively bonded to the negative electrode lead and the positive electrode lead of the first battery cell to be connected in parallel with each other, wherein surfaces of the first battery cell and the second battery cell stacked in contact with each other are bonded to each other, The secondary battery further includes a third battery cell that is subjected to the activation process and has a structure in which the electrode assembly is embedded in a bag and a negative electrode lead and a positive electrode lead protrude to the outside of the bag, wherein the third battery cell is stacked on the second battery cell at a relative position to the first battery cell, and the negative electrode lead and the positive electrode lead of the third battery cell are respectively bonded to the negative electrode lead and the positive electrode lead of each of the first battery cell and the second battery cell so as to be connected in parallel with each other, wherein surfaces of the third battery cell and the second battery cell stacked in contact with each other are bonded to each other, wherein each of the bag of the first battery cell and the bag of the third battery cell has two planes parallel to each other, one of the two planes is a narrow surface with a relatively narrow area, and the other plane is a wide surface with a relatively wide area, and The area of ​​both surfaces of the second battery cell disposed between the first battery cell and the third battery cell is the same as the area of ​​the wide surface of the bag of each of the first battery cell and the third battery cell, so that both surfaces of the second battery cell are bonded.

12. The secondary battery according to claim 11, wherein The bonding between the first battery cell and the second battery cell is performed by means of an adhesive tape adhered between the first battery cell and the second battery cell.

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