Pouch-type secondary battery and apparatus and method for sealing pouch-type secondary battery

Abstract

A pouch-type secondary battery according to the present application and an apparatus and method for sealing the same can provide a secondary battery having a high adhesion density by sealing a plurality of regions of a pouch-type case without requiring an additional manufacturing process. Furthermore, not only can the adhesion of a case material of the pouch-type case be improved, but also the adhesion between the end of an electrode and the end of a separator of an electrode assembly can be improved, so that the occurrence of overvoltage or the acceleration of electrolyte consumption can be prevented. A secondary battery according to the present application includes an electrode assembly in which electrodes and separators are alternately stacked, and a pouch accommodating the electrode assembly, a portion of the pouch including a sealing portion as a bonding portion. The sealing portion can include a first sealing region spaced apart from the electrode assembly by a predetermined distance and disposed at an edge of the pouch, and a second sealing region which is a region corresponding to the electrode assembly.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2021-0128364, filed on September 28, 2021, and Korean Patent Application No. 10-2022-0121202, filed on September 23, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a pouch-type secondary battery and an apparatus and method for sealing the pouch-type secondary battery. More specifically, it relates to a sealing apparatus and sealing method for improving the adhesion between the electrodes and the separator disposed in the secondary battery, thereby preventing overvoltage or rapid consumption of electrolyte that may occur depending on the bonding state of the electrodes and the separator, and a pouch-type secondary battery using the sealing apparatus and sealing method. Background Technology

[0004] Recently, with the gradual depletion of fossil fuels, interest in alternative energy sources that can replace them has increased due to limited fuel availability and the growing importance of preventing environmental pollution. Therefore, research and development of power generation technologies based on energy sources with minimal environmental impact, such as solar, hydro, wind, ocean, and biomass energy, are actively underway.

[0005] In particular, research is actively underway on rechargeable secondary batteries, and continuous development is being made in various aspects such as the materials, efficiency, and structure of secondary batteries.

[0006] In terms of structure, secondary batteries are mainly classified into cylindrical, prismatic, or pouch-type batteries. Therefore, research and development are conducted based on the structural characteristics corresponding to each type of secondary battery to improve energy efficiency and energy density or prevent low energy efficiency.

[0007] In terms of energy efficiency and energy density, pouch cells are more advantageous than other types of cells, but continuous efforts are being made to improve aspects such as the arrangement, combination, or sealing of components to ensure higher efficiency. Summary of the Invention

[0008] Technical issues

[0009] Pouch cells have an electrode assembly housed within a pouch-shaped casing, where electrodes and separators are alternately stacked, ensuring high energy density. However, to maintain high energy density, the electrodes and separators need to be well bonded together, and high precision is required during the secondary battery manufacturing process to ensure high adhesion.

[0010] However, in the manufacturing process of secondary batteries, when only the shell portion of the pouch-type casing is sealed, there is a risk that the ends of the electrodes and the ends of the separator may not bond properly, leading to overvoltage or accelerated electrolyte consumption. Furthermore, performing additional sealing steps to bond the ends of the electrodes and the separator may take longer or require separate sealing tools, resulting in inefficiencies in the manufacturing process.

[0011] The present invention, designed to solve the above problems, aims to provide a secondary battery with high adhesive density through multiple areas of a sealed bag-shaped housing without requiring additional manufacturing processes.

[0012] Technical solution

[0013] The secondary battery according to the present invention may include: an electrode assembly in which electrodes and separators are alternately stacked; and a bag for receiving the electrode assembly, a portion of the bag including a sealing portion as a connecting part. The sealing portion may include: a first sealing region spaced apart from the electrode assembly at a predetermined distance and disposed at the edge of the bag, and a second sealing region corresponding to the electrode assembly.

[0014] The second sealing area may be an area corresponding to the edge of the electrode assembly, and the edge of the electrode assembly may correspond to the end of the electrode and the end of the diaphragm.

[0015] The first sealing region may be the region corresponding to the bonding region at the edge of the bag, and the second sealing region may be the region corresponding to the bonding region at the end of the electrode and the end of the diaphragm.

[0016] The adhesive force between the end of the electrode and the end of the diaphragm corresponding to the edge of the electrode assembly can be greater than the adhesive force between the portion of the electrode other than the end and the portion of the diaphragm other than the end.

[0017] The adhesive force of the second sealing region can correspond to the adhesive force of the first sealing region.

[0018] When viewed from above, the area of ​​the second sealing region can be 7% to 14% of the area of ​​the bag.

[0019] The first sealing region and the second sealing region can be regions that are sealed by combining heat and pressure.

[0020] The area of ​​the second sealing region can be larger than the area of ​​the first sealing region.

[0021] When viewed from above, the second sealing area may include the area that overlaps with the electrode assembly.

[0022] An apparatus for sealing a secondary battery according to the present invention may include: a clamp having a bag on which an electrode assembly is received; and a sealing tool that seals a first sealing region disposed at the edge of the bag and a second sealing region disposed in a region corresponding to the electrode assembly in the bag. The sealing tool performs the sealing of the first sealing region and the second sealing region using heat and pressure.

[0023] The sealing tool may include an upper sealing tool and a lower sealing tool. The upper sealing tool may include a first upper block and a second upper block, and the lower sealing tool may include a first lower block and a second lower block. The first upper block of the upper sealing tool and the first lower block of the lower sealing tool may be disposed in corresponding areas, and the first upper block and the first lower block may perform sealing of the first sealing area.

[0024] The second upper block of the upper sealing tool and the second lower block of the lower sealing tool can be disposed in corresponding areas, and the second upper block and the second lower block can perform sealing of the second sealing area while pressing a portion of the electrode assembly.

[0025] In the sealing tool, the first upper block and the second upper block can be configured as a single piece.

[0026] The method for sealing a secondary battery according to the present invention may include: a setting step of setting the secondary battery on a fixture, the secondary battery including a bag containing an electrode assembly in which electrodes and separators are alternately stacked; and a sealing step of sealing a first sealing region disposed on the edge of the bag disposed on the fixture and a second sealing region corresponding to the electrode assembly in the bag by using a sealing tool.

[0027] The sealing process may include a sealing process performed such that the adhesive force between the end of the electrode corresponding to the edge of the electrode assembly and the end of the diaphragm is greater than the adhesive force between the portion of the electrode other than the end and the portion of the diaphragm other than the end.

[0028] The sealing process may include a sealing process performed such that the adhesive force of the second sealing region corresponds to the adhesive force of the first sealing region.

[0029] The sealing process can simultaneously seal the first sealing area and the second sealing area by using the sealing tool.

[0030] Beneficial effects

[0031] The pouch-type secondary battery and the apparatus and method for sealing the pouch-type secondary battery according to the present invention can provide a secondary battery with high adhesive density by sealing multiple regions of the pouch-type housing without the need for additional manufacturing processes.

[0032] The pouch-type secondary battery and the apparatus and method for sealing the pouch-type secondary battery according to the present invention can not only improve the adhesive force of the shell material of the pouch-type housing, but also improve the adhesive force between the ends of the electrodes and the ends of the separator of the electrode assembly, thereby preventing the occurrence of overvoltage or the acceleration of electrolyte consumption. Attached Figure Description

[0033] Figure 1 This is a perspective view showing a battery cell of a pouch-type secondary battery according to an embodiment of the present invention.

[0034] Figure 2 This is an exploded perspective view showing a battery cell of a pouch-type secondary battery according to an embodiment of the present invention.

[0035] Figure 3 This is a flowchart illustrating the process of manufacturing a battery cell for a pouch-type secondary battery according to an embodiment of the present invention.

[0036] Figure 4 This is a perspective view showing the process of a battery cell for a sealed pouch-type secondary battery according to an embodiment of the present invention.

[0037] Figure 5 This is a cross-sectional view showing the process of a battery cell for a sealed pouch-type secondary battery according to an embodiment of the present invention.

[0038] Figure 6 This is a top view showing multiple sealed areas of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention. Detailed Implementation

[0039] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. However, the invention may be implemented in various forms and should not be construed as limited to the embodiments listed herein.

[0040] To clearly describe the invention, detailed descriptions of irrelevant parts or related known techniques that may unnecessarily obscure the subject matter of the invention will be excluded. In the drawings, the same reference numerals refer to the same elements throughout the specification.

[0041] Furthermore, the terms or words used in this specification and claims should not be construed as having a general meaning or a dictionary-based meaning, but should be interpreted as having a meaning and concept that is within the scope of the invention, based on the principle that the inventor is able to properly define the concepts of the terms in order to best describe his or her invention.

[0042] Figure 1 This is a perspective view showing a battery cell of a pouch-type secondary battery according to an embodiment of the present invention. Figure 2 This is an exploded perspective view showing a battery cell of a pouch-type secondary battery according to an embodiment of the present invention.

[0043] In the following text, reference will be made to Figure 1 and Figure 2 The structure of the battery cell 10 of the pouch-type secondary battery is described.

[0044] The battery unit 10 may include an electrode assembly 12 and a pouch 11, wherein the pouch 11 is provided with a receiving portion 11a capable of accommodating the electrolyte and the electrode assembly 12.

[0045] The bag 11 may have portions that are attached (or joined) to form a seal. The seal may include multiple sealing areas.

[0046] The electrode assembly 12 can be a rechargeable and dischargeable device, and has a structure in which electrodes 12c and diaphragm 12d are aggregated to be stacked alternately.

[0047] Electrode 12c may include a positive electrode 12a and a negative electrode 12b. Electrode assembly 12 may have a structure in which the positive electrode 12a, the diaphragm 12d, and the negative electrode 12b are aggregated and stacked alternately.

[0048] The positive electrode 12a may include a positive current collector and a positive active material applied to the positive current collector, and the negative electrode 12b may include a negative current collector and a negative active material applied to the negative current collector.

[0049] The positive current collector can be made of, for example, a foil made of aluminum (Al) material.

[0050] The positive electrode active material may include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture including at least one of the above.

[0051] For example, the positive electrode active material may include a Hi Ni-based positive electrode material. The Hi Ni-based positive electrode material may include one or more of LiNiMnCoO-based, LiNiCoAl-based, and LiNiMnCoAl-based materials. Here, the nickel (Ni) content may be, for example, from 0.5 mol to 0.95 mol.

[0052] The negative current collector can be made of, for example, a foil made of copper (Cu) or nickel (Ni) material.

[0053] In one example, the negative electrode active material may include a material comprising synthetic graphite. In another example, the negative electrode active material may include lithium metal, lithium alloys, carbon, petroleum coke, activated carbon, graphite, silicon compounds, tin compounds, titanium compounds, or alloys thereof.

[0054] The diaphragm 12d is made of an insulating material, thus electrically insulating the positive electrode 12a and the negative electrode 12b from each other. The diaphragm 12d may be made of, for example, a microporous polyolefin-based resin such as polyethylene or polypropylene.

[0055] The battery cell 10 may include electrode leads 13 that are electrically connected to the electrodes 12c of the electrode assembly 12.

[0056] Figure 3 The process of manufacturing a battery cell for a pouch-type secondary battery according to an embodiment of the present invention is shown.

[0057] Electrode assembly unit 12-1 may have a structure in which negative electrode 12b, separator 12d, positive electrode 12a, separator 12d' and negative electrode 12b' are stacked alternately. Alternatively, electrode assembly unit 12-1 may have a structure in which positive electrode, separator, negative electrode, separator and positive electrode are stacked alternately.

[0058] The electrode assembly 12 may have a structure in which the electrode assembly units 12-1 are repeatedly stacked. For example, multiple electrode assembly units 12-1 may be stacked to form the electrode assembly 12.

[0059] The electrode assembly 12 can be housed in the receiving portion 11a of the bag 11. The electrolyte can be housed in the remaining space besides the space for housing the electrode assembly 12 in the receiving portion 11a.

[0060] The bag 11 may have an edge with a first sealing region 14a. The first sealing region 14a may be located in an area spaced at a predetermined distance from the electrode assembly 12. The shell materials of the bag 11 may be bonded together in the first sealing region 14a to maintain the battery cell 10 in a sealed (or hermetically sealed) state. The bonding (or sealing) of the shell materials of the bag 11 in the first sealing region 14a may be performed by methods such as thermal fusion using heat and pressure.

[0061] The second sealing region 14b may be a region corresponding to the electrode assembly 12. For example, the second sealing region 14b may be a region corresponding to the edge of the electrode assembly 12. The second sealing region 14b may be a region corresponding to the end of the electrode 12c and the end of the separator 12d. In other words, when the battery cell 10 is viewed from above, the second sealing region 14b may include a region overlapping with the electrode assembly 12.

[0062] The ends of electrode 12c and diaphragm 12d can be joined (sealed) to each other in the second sealing region 14b. The joining (or sealing) of the ends of electrode 12c and diaphragm 12d can be performed by methods such as thermal fusion using heat and pressure.

[0063] Figure 4 The process of a battery cell for a sealed pouch-type secondary battery according to an embodiment of the present invention is shown.

[0064] The sealing device may include a clamp on which the object to be sealed is mounted, and a sealing tool 20 for sealing the object.

[0065] The sealing tool 20 can use heat and pressure to seal a portion of each of the bag 11 and electrode assembly 12 of the battery cell 10. For example, the sealing tool 20 can press a portion of the bag 11 while it is heated. In this case, a portion of the electrode assembly 12 can also be pressed.

[0066] The battery cell 10 can be sealed by the sealing tool 20 of the sealing device.

[0067] The sealing part 14 of the battery cell 10 (see Figure 6 It may include a first sealing region 14a disposed at the edge of the bag 11, and a second sealing region 14b disposed in the region corresponding to the edge of the electrode assembly 12 housed in the bag 11.

[0068] The first sealing region 14a and the second sealing region 14b of the sealing portion 14 of the battery cell 10 can be sealed by the sealing tool 20.

[0069] The sealing device may include a clamp on which the battery unit 10 may be mounted. Alternatively, the sealing device may include a clamp on which a bag 11 containing the electrode assembly 12 may be mounted.

[0070] The sealing tool 20 may include an upper sealing tool 21 and a lower sealing tool 22. Each of the upper sealing tool 21 and the lower sealing tool 22 may be included in the sealing tool 20 as a separate component, or the upper sealing tool 21 and the lower sealing tool 22 may be integrally formed and included in the sealing tool 20.

[0071] The upper sealing tool 21 may include a first upper block 21a and a second upper block 21b. Each of the first upper block 21a and the second upper block 21b may be included in the upper sealing tool 21 as a separate component, or the first upper block 21a and the second upper block 21b may be integrally formed and included in the upper sealing tool 21.

[0072] The lower sealing tool 22 may include a first lower block 22a and a second lower block 22b. Each of the first lower block 22a and the second lower block 22b may be included in the lower sealing tool 22 as a separate component, or the first lower block 22a and the second lower block 22b may be integrally formed and included in the lower sealing tool 22.

[0073] The sealing tool 20 may include an upper lifting device 21c and a lower lifting device 22c. The upper sealing tool 21 can be raised / lowered via the upper lifting device 21c, and the lower sealing tool 22 can be raised / lowered via the lower lifting device 22c.

[0074] The first upper block 21a and the first lower block 22a can be placed in corresponding areas. The second upper block 21b and the second lower block 22b can be placed in corresponding areas.

[0075] The first upper block 21a and the first lower block 22a can seal a first sealing region 14a located at the edge of the bag 11. The second upper block 21b and the second lower block 22b can seal a second sealing region 14b, which is the region corresponding to the electrode assembly 12 (or the edge of the electrode assembly 12). The second upper block 21b and the second lower block 22b can seal the second sealing region 14b while pressing a portion of the electrode assembly 12.

[0076] When viewed from above, the second sealing region 14b may include the area overlapping with the electrode assembly 12. When viewed from above, the area of ​​the second sealing region 14b may be 7% to 14% of the area of ​​the bag 11. When a seal is performed such that the second sealing region 14b has the area ratio relative to the area of ​​the bag 11 as described above, the adhesive force, described later, can be improved to effectively prevent overvoltage or accelerated electrolyte consumption.

[0077] The sealing tool 20 can simultaneously seal the first sealing region 14a and the second sealing region 14b, which not only improves the adhesion of the edge of the bag 11, but also improves the adhesion between the end of the electrode 12c and the end of the diaphragm 12d. Therefore, it can prevent the occurrence of overvoltage in the electrode assembly 12 or the accelerated consumption of electrolyte in the bag 11.

[0078] Figure 5 The process of a battery cell for a sealed pouch-type secondary battery according to an embodiment of the present invention is shown.

[0079] The battery cell 10, including the bag 11 containing the electrode assembly 12, can be placed on the clamp of the sealing device for sealing.

[0080] The first sealing area 14a at the edge of the bag 11 can be sealed by pressing (or combining) the first upper block 21a and the first lower block 22a with heat and pressure.

[0081] The second sealing region 14b can be sealed by pressing (or combining) the second upper block 21b and the second lower block 22b with heat and pressure. The second sealing region is the region corresponding to the edge of the electrode assembly 12 in the bag 11.

[0082] The seal can be performed using heat and pressure by a sealing tool, such that the adhesive force between the end of the electrode 12c corresponding to the edge of the electrode assembly 12 and the end of the diaphragm 12d is greater than the adhesive force between the portion of the electrode 12c other than the end and the portion of the diaphragm 12d other than the end.

[0083] The first sealing region 14a and the second sealing region 14b can be simultaneously pressed (or combined) by heat and pressure using the sealing tool 20, thereby sealing the first sealing region and the second sealing region.

[0084] The sealing can be performed by heat and pressure using the sealing tool 20, so that the adhesive force of the second sealing region 14b corresponds to the adhesive force of the first sealing region 14a.

[0085] Figure 6 Multiple sealed areas of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention are shown. Figure 6 The structure of the battery cell 10 is shown when viewed from above.

[0086] The battery cell 10 may include an electrode assembly 12, a pouch 11 for housing the electrode assembly 12, and electrode leads 13 electrically connected to the electrode assembly 12.

[0087] The first sealing region 14a may be provided in the region corresponding to the edge of the bag 11. The first sealing region 14a may be provided in the edge of the bag 11 corresponding to the direction in which the electrode lead 13 electrically connects the electrode assembly 12 to the outside is positioned.

[0088] The second sealing region 14b may be disposed in the region corresponding to the edge of the electrode assembly 12. The second sealing region 14b may be disposed in the region corresponding to the edge of the electrode assembly 12, the edge of the second electrode assembly being the edge corresponding to the direction in which the electrode lead 13 is disposed.

[0089] The second sealing region 14b may have a shape corresponding to the shape of the edge of one side of the electrode assembly 12.

[0090] The second sealing region 14b may include a portion of the shell material region of the bag 11 and an area corresponding to the edge of the electrode assembly 12. In other words, when viewed from above, the second sealing region 14b may include an area overlapping with the electrode assembly 12. When viewed from above, the area of ​​the second sealing region 14b may be 7% to 14% of the area of ​​the bag 11.

[0091] The area of ​​the second sealing region 14b can be larger than the area of ​​the first sealing region 14a.

[0092] The adhesive force of the second sealing region 14b can correspond to the adhesive force of the first sealing region 14a.

[0093] Sealing can be performed on multiple areas (e.g., first sealing area 14a and second sealing area 14b), thereby improving the adhesion of the edge of the pouch 11 of the battery cell 10 and also improving the adhesion between the end of the electrode 12c of the electrode assembly 12 and the end of the separator 12d.

[0094] Although the invention has been described with reference to limited embodiments and accompanying drawings, the invention is not limited thereto. Within the scope of the technical concept and the equivalents of the appended claims, those skilled in the art can implement the invention in various ways.

Claims

1. An apparatus for sealing a secondary battery, the apparatus comprising: It is equipped with a clamp that holds an electrode assembly in which electrodes and diaphragms are alternately stacked; and A sealing tool configured to seal a first sealing region disposed at the edge of the bag and a second sealing region disposed in a region corresponding to the edge of the electrode assembly in the bag, wherein the edge of the electrode assembly corresponds to the end of the electrode and the end of the diaphragm. The sealing tool includes an upper sealing tool and a lower sealing tool. The upper sealing tool includes a first upper block and a second upper block, and the lower sealing tool includes a first lower block and a second lower block. The first upper block of the upper sealing tool and the first lower block of the lower sealing tool are disposed in corresponding areas, and the first upper block and the first lower block perform sealing of the first sealing area. The second upper block of the upper sealing tool and the second lower block of the lower sealing tool are disposed in corresponding areas, and the second upper block and the second lower block perform sealing of the second sealing area while pressing a portion of the electrode assembly. In the sealing tool, the first upper block and the second upper block are configured as a single unit, so that the sealing tool uses heat and pressure to simultaneously seal the first sealing area and the second sealing area.

2. A method for sealing a secondary battery using the apparatus according to claim 1, the method comprising: In the setting process, a secondary battery is placed on the fixture, the secondary battery comprising a bag containing an electrode assembly in which electrodes and separators are alternately stacked; and The sealing process involves simultaneously sealing a first sealing region located at the edge of the bag, which is positioned on the clamp, and a second sealing region corresponding to the edge of the electrode assembly in the bag, using the sealing tool, wherein the edge of the electrode assembly corresponds to the end of the electrode and the end of the diaphragm.

3. The method of claim 2, wherein the sealing process comprises a sealing process performed such that the adhesive force between the end of the electrode corresponding to the edge of the electrode assembly and the end of the diaphragm is greater than the adhesive force between the portion of the electrode other than the end and the portion of the diaphragm other than the end.

4. The method of claim 2, wherein the sealing process comprises a sealing process performed such that the adhesive force of the second sealing region corresponds to the adhesive force of the first sealing region.

5. A secondary battery sealed by the method according to claim 2, comprising: An electrode assembly in which electrodes and diaphragms are stacked alternately; and A bag housing the electrode assembly, a portion of which includes a sealing portion as a connecting part. The sealing part includes: A first sealing region, spaced a predetermined distance from the electrode assembly and disposed at the edge of the bag, and The second sealing region is a region corresponding to the edge of the electrode assembly, wherein the edge of the electrode assembly corresponds to the end of the electrode and the end of the diaphragm. When viewed from above, the area of ​​the second sealing region is 7% to 14% of the area of ​​the bag.

6. The secondary battery according to claim 5, wherein the first sealing region is the region corresponding to the bonding region at the edge of the bag, and The second sealing region is the region corresponding to the bonding region at the end of the electrode and the end of the diaphragm.

7. The secondary battery of claim 5, wherein the adhesive force between the end of the electrode corresponding to the edge of the electrode assembly and the end of the separator is greater than the adhesive force between the portion of the electrode other than the end and the portion of the separator other than the end.

8. The secondary battery according to claim 5, wherein the adhesive force of the second sealing region corresponds to the adhesive force of the first sealing region.

9. The secondary battery according to claim 5, wherein the first sealing region and the second sealing region are regions that are combined and sealed by heat and pressure.

10. The secondary battery according to claim 5, wherein the area of ​​the second sealing region is larger than the area of ​​the first sealing region.

11. The secondary battery of claim 5, wherein, when viewed from above, the second sealing region includes a region overlapping the electrode assembly.

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