Pouch-type secondary battery, sealing device for the secondary battery, and sealing method for the secondary battery

Abstract

The pouch-type secondary battery, the sealing device for the secondary battery, and the sealing method for the secondary battery according to the present invention can provide a secondary battery having a high adhesion density by sealing a plurality of regions of the pouch-type case without performing additional manufacturing processes. Also, the adhesion of the packaging material of the pouch-type case as well as the ends of the electrodes and the ends of the separator in the electrode assembly is improved, thereby preventing overvoltage and accelerated consumption of the electrolyte. The secondary battery according to the present invention may include an electrode assembly in which electrodes and separators are alternately stacked, and a pouch that houses the electrode assembly and includes a sealing portion that is a portion joined to the electrode assembly, and the sealing portion may include a first sealing area formed on an edge of the pouch a predetermined distance away from the electrode assembly, and a second sealing area that is an area corresponding to the electrode assembly.

Description

Technical Field

[0001] This application claims the benefit of priority based on 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, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a pouch-type secondary battery, a sealing device for the secondary battery, and a sealing method for the secondary battery. More specifically, the present invention relates to a sealing device and a sealing method capable of improving the adhesive force between an electrode and a separator in order to prevent overvoltage that may occur due to the adhesion state between the electrode and the separator included in a secondary battery cell or rapid consumption of an electrolyte, and to a pouch-type secondary battery.

Background Art

[0003] In recent years, due to the gradual depletion of fossil fuels and the limited amount of fuel, as well as the increasing importance of environmental pollution prevention, the interest in alternative energy that can replace fossil fuels has been increasing. Accordingly, research and development of power generation technologies based on energy sources that have little impact on environmental pollution, such as solar heat, hydropower, wind power, ocean energy, and biomass energy, have been actively conducted.

[0004] In particular, research on secondary batteries that can be repeatedly charged has been actively conducted, and development has been continuously carried out in various aspects such as the materials, efficiency, and structure of secondary batteries.

[0005] In terms of the structural aspect of secondary batteries, cylindrical batteries, prismatic batteries, or pouch-type batteries are the mainstream. Accordingly, research and development have been conducted to improve energy efficiency and energy density or to prevent energy inefficiency according to the structural characteristics corresponding to each form of various forms of secondary batteries.

[0006] The pouch-type battery has advantages over other types of batteries in terms of energy efficiency and density. However, in order to ensure higher efficiency, continuous improvements have been attempted in aspects such as the arrangement, bonding, and sealing of the components.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The pouch-type battery is a form in which an electrode assembly is housed in a pouch-type case, and by housing an electrode assembly in which electrodes and separator membranes are alternately laminated in the case, a high energy density can be ensured. However, in order to maintain high efficiency, the adhesion between the electrodes and the separator membrane must be completely achieved, and in order to ensure high adhesiveness, high precision is required in the manufacturing process of the secondary battery.

[0008] However, in the manufacturing process of the secondary battery, when only the seal of the packaging material part of the pouch-type case is performed, the adhesion at the ends of the electrodes and the separator membrane is not completely achieved, and there are problems such as the generation of overvoltage and the acceleration of the consumption of the electrolytic solution. In addition, when passing through an additional sealing process for the adhesion at the ends of the electrodes and the separator membrane, the manufacturing time becomes longer and a separate sealing tool is required, resulting in inefficiency in the manufacturing process.

[0009] The present invention is for solving the above problems, and by enabling sealing to be performed in a plurality of regions of the pouch-type case without performing an additional manufacturing process, it provides a secondary battery having a high adhesion density.

Means for Solving the Problems

[0010] The secondary battery according to the present invention includes an electrode assembly in which electrodes and separator membranes are alternately laminated, and a pouch including the electrode assembly and having a seal part which is a part joined at a part, and the seal part may include a first seal region formed at an edge of the pouch at a predetermined distance from the electrode assembly, and a second seal region which is a region corresponding to the electrode assembly.

[0011] The second seal area is 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 separation membrane.

[0012] The first seal area is an area corresponding to the adhesion area of the edge of the pouch, and the second seal area may correspond to the adhesion area of the ends of the electrode and the separation membrane.

[0013] The adhesive force between the end of the electrode corresponding to the electrode assembly and the end of the separation membrane may be greater than the adhesive force between the remaining portion excluding the end of the electrode and the remaining portion excluding the end of the separation membrane.

[0014] The adhesive force of the second seal area may correspond to the adhesive force of the first seal area.

[0015] The second seal area may have an area value of 7% to 14% of the area value of the pouch when viewed from above.

[0016] The first seal area and the second seal area may be areas that are adhered and sealed based on heat and pressure.

[0017] The area of the second seal area may be larger than the area of the first seal area.

[0018] The second seal area may include an area overlapping the electrode assembly when viewed from above.

[0019] In an apparatus for sealing a secondary battery according to the present invention, it includes a jig on which a pouch containing an electrode assembly is disposed, and a sealing tool capable of sealing a first seal area formed at the edge of the pouch and a second seal area formed in an area corresponding to the electrode assembly of the pouch. The sealing tool may seal the first seal area and the second seal area based on heat and pressure.

[0020] The sealing tool includes an upper block and a lower block. The upper block includes a first upper block and a second upper block. The lower block includes a first lower block and a second lower block. The first upper block of the upper block and the first lower block of the lower block are formed at corresponding positions to each other. The first upper block and the first lower block may seal the first seal area.

[0021] The second upper block of the upper block and the second lower block of the lower block are formed at corresponding positions to each other. The second upper block and the second lower block may press a part of the electrode assembly to seal the second seal area.

[0022] In the sealing tool, the first upper block and the second upper block may be integrally formed.

[0023] In a method for sealing a secondary battery according to the present invention, a step of disposing a secondary battery including a pouch in which an electrode assembly is accommodated on a jig, and a step of using a sealing tool to seal a first seal area formed at an edge of the pouch disposed on the jig and a second seal area corresponding to the electrode assembly of the pouch may be included.

[0024] The sealing step may further include a step of sealing such that an adhesive force between an end of an electrode corresponding to the electrode assembly and an end of a separator is greater than an adhesive force between the remaining portion excluding the end of the electrode and the remaining portion excluding the end of the separator.

[0025] The sealing step may further include a step of sealing such that the adhesive force of the second seal area corresponds to the adhesive force of the first seal area.

[0026] The sealing step may further include a step of simultaneously sealing the first seal area and the second seal area using the sealing tool.

Advantages of the Invention

[0027] The pouch-type secondary battery, the sealing device for the secondary battery, and the sealing method for the secondary battery according to the present invention can provide a secondary battery having a high adhesion density by performing sealing in a plurality of regions of the pouch-type case without performing further manufacturing steps.

[0028] The pouch-type secondary battery, the sealing device for the secondary battery, and the sealing method for the secondary battery according to the present invention can prevent the generation of overvoltage and the acceleration of the consumption of the electrolytic solution by improving the adhesiveness of not only the packaging material of the pouch-type case but also the ends of the electrodes and the ends of the separator in the electrode assembly.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0030] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention can be realized in various different forms and is not limited or restricted to the following embodiments.

[0031] To clearly explain the present invention, detailed descriptions of parts not related to the explanation or related known technologies that may obscure the gist of the present invention are omitted. When adding reference numerals to the components of each drawing in this specification, the same or similar reference numerals are assigned to the same or similar components throughout the specification.

[0032] In addition, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, they should be construed as meanings and concepts consistent with the technical idea of the present invention.

[0033] FIG. 1 is a perspective view of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention.

[0034] Hereinafter, with reference to FIGS. 1 and 2, the configuration of the battery cell 10 of the pouch-type secondary battery will be described.

[0035] The battery cell 10 may include an electrode assembly 12 and a pouch 11 in which a housing portion 11a capable of housing an electrolytic solution and the electrode assembly 12 is formed.

[0036] A part of the pouch 11 may be adhered (or joined) to form a seal portion. The seal portion may include a plurality of seal regions.

[0037] The electrode assembly 12 is an element capable of charging and discharging, and may have a structure in which an electrode 12c and a separator 12d are aggregated and alternately laminated.

[0038] The electrode 12c may include a positive electrode 12a and a negative electrode 12b. The electrode assembly 12 may form a structure in which the positive electrode 12a, the separator 12d, and the negative electrode 12b are alternately aggregated and laminated.

[0039] The positive electrode 12a includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, and the negative electrode 12b may include a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector.

[0040] The positive electrode current collector may be made of, for example, a foil made of aluminum (Al).

[0041] The positive electrode active material may be composed of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing one or more of these.

[0042] As another example, the positive electrode active material may be made of a Hi Ni-based positive electrode material. Here, the Hi Ni-based positive electrode material may include one or more of LiNiMnCoO-based, LiNiCoAl-based, or LiMiMnCoAl-based. At this time, the content of nickel (Ni) may be, for example, 0.5 mol to 0.95 mol.

[0043] The negative electrode current collector may be made of, for example, a foil made of copper (Cu) or nickel (Ni).

[0044] As an example, the negative electrode active material may be made of a material containing artificial graphite. Also, as another example, the negative electrode active material may be made of lithium metal, a lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof.

[0045] The separator 12d is made of an insulating material and electrically insulates between the positive electrode 12a and the negative electrode 12b. Here, the separator 12d may be formed of a polyolefin-based resin film having microporosity, such as polyethylene or polypropylene.

[0046] The battery cell 10 may include an electrode lead 13 that is electrically connected to the electrode 12c of the electrode assembly 12.

[0047] FIG. 3 shows the manufacturing process of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention.

[0048] The electrode assembly unit 12-1 may have a structure in which the negative electrode 12b, the separator 12d, the positive electrode 12a, the separator 12d', and the negative electrode 12b' are alternately laminated. Further, the electrode assembly unit 12-1 may have a structure in which the positive electrode, the separator, the negative electrode, the separator, and the positive electrode are alternately laminated.

[0049] The electrode assembly 12 may have a structure in which the electrode assembly units 12-1 are repeatedly laminated. For example, the electrode assembly 12 may be formed by laminating a plurality of electrode assembly units 12-1.

[0050] The accommodating portion 11a of the pouch 11 accommodates the electrode assembly 12. The electrolyte is accommodated in the remaining space of the space in the accommodating portion 11a where the electrode assembly 12 is accommodated.

[0051] A first seal region 14a may be formed at the edge of the pouch 11. The first seal region 14a may be formed in a region spaced a predetermined distance from the electrode assembly 12. By adhering the packaging materials of the pouch 11 to each other in the first seal region 14a, the battery cell 10 can maintain a sealed (or airtight) state. The adhesion (or sealing) of the packaging materials of the pouch 11 in the first seal region 14a may be performed by a method such as heat fusion based on heat and pressure.

[0052] The second seal region 14b may be a region corresponding to the electrode assembly 12. For example, the second seal region 14b may be a region corresponding to the edge of the electrode assembly 12. Further, the second seal 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 seal region 14b may include a region overlapping the electrode assembly 12.

[0053] In the second seal region 14b, adhesion (or sealing) may be performed between the end of the electrode 12c and the end of the separation film 12d. The adhesion (or sealing) between the end of the electrode 12c and the end of the separation film 12d may be performed by a method such as heat fusion based on heat and pressure.

[0054] FIG. 4 shows the sealing process of the battery cell of the pouch-type secondary battery according to an embodiment of the present invention.

[0055] The sealing device may include a jig on which a sealing target is disposed and a sealing tool 20 for sealing the sealing target.

[0056] The sealing tool 20 may seal a part of the pouch 11 and the electrode assembly 12 of the battery cell 10 based on heat and pressure. For example, the sealing tool 20 may press a part of the pouch 11 in a heated state. In this case, a part of the electrode assembly 12 may also be pressurized.

[0057] The battery cell 10 may be sealed based on the sealing tool 20 of the sealing device.

[0058] The seal portion 14 of the battery cell 10 may include a first seal region 14a formed at the edge of the pouch 11 and a second seal region 14b formed in a region corresponding to the edge of the electrode assembly 12 housed in the pouch 11.

[0059] The first seal region 14a and the second seal region 14b of the seal portion 14 of the battery cell 10 may be sealed based on the sealing tool 20.

[0060] The sealing device may include a jig on which the battery cell 10 can be disposed. Further, the sealing device may include a jig on which the pouch 11 containing the electrode assembly 12 can be disposed.

[0061] The sealing tool 20 may include an upper sealing tool 21 and a lower sealing tool 22. The upper sealing tool 21 and the lower sealing tool 22 may be included in the sealing tool 20 as separate components, or the upper sealing tool 21 and the lower sealing tool 22 may be integrally formed and included in the sealing tool 20.

[0062] The upper sealing tool 21 may include a first upper block 21a and a second upper block 21b. The first upper block 21a and the second upper block 21b may be included in the upper sealing tool 21 as separate components, or the first upper block 21a and the second upper block 21b may be integrally formed and included in the upper sealing tool 21.

[0063] The lower sealing tool 22 may include a first lower block 22a and a second lower block 22b. The first lower block 22a and the second lower block 22b may be included in the lower sealing tool 22 as separate components, or the first lower block 22a and the second lower block 22b may be integrally formed and included in the lower sealing tool 22.

[0064] The sealing tool 20 may include an upper lifting means 21c and a lower lifting means 22c. The upper sealing tool 21 can be lifted / lowered by the upper lifting means 21c, and the lower sealing tool 22 can be lifted / lowered by the lower lifting means 22c.

[0065] The first upper block 21a and the first lower block 22a may be formed at corresponding positions to each other. Also, the second upper block 21b and the second lower block 22b may be formed at corresponding positions to each other.

[0066] The first upper block 21a and the first lower block 22a may seal the first seal region 14a formed at the edge of the pouch 11. Also, the second upper block 21b and the second lower block 22b may seal the second seal region 14b which is a 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 may press a part of the electrode assembly 12 to seal the second seal region 14b.

[0067] The second seal region 14b may include a region overlapping with the electrode assembly 12 when viewed from above. The second seal region 14b may have an area value of 7% to 14% of the area value of the pouch 11 when viewed from above. When the seal is performed such that the second seal region 14b has the area ratio as described above with respect to the area of the pouch 11, the generation of overvoltage and the acceleration of the consumption of the electrolytic solution are effectively prevented by the improvement of the adhesiveness described later.

[0068] The seal tool 20 can seal the first seal region 14a and the second seal region 14b at once, and can improve the adhesive force not only at the edge of the pouch 11 but also between the ends of the electrode 12c and the separator 12d. Thereby, it is possible to prevent the generation of overvoltage in the electrode assembly 12 and the acceleration of the consumption of the electrolytic solution in the pouch 11.

[0069] FIG. 5 shows the sealing process of the battery cell of the pouch-type secondary battery according to an embodiment of the present invention.

[0070] The battery cell 10 including the pouch 11 in which the electrode assembly 12 is housed is arranged on the jig of the sealing device for sealing.

[0071] The first seal region 14a formed at the edge of the pouch 11 is sealed by being crimped (or joined) based on heat and pressure by the first upper block 21a and the first lower block 22a.

[0072] The second seal region 14b, which is a region corresponding to the edge of the electrode assembly 12 within the pouch 11, is sealed by being pressure-bonded (or joined) based on heat and pressure by the second upper block 21b and the second lower block 22b.

[0073] By being sealed based on heat and pressure by the seal tool 20, the adhesive force between the end of the electrode 12c corresponding to the edge of the electrode assembly 12 and the end of the separator 12d becomes greater than the adhesive force between the remaining portion excluding the end of the electrode 12c and the remaining portion excluding the end of the separator 12d.

[0074] The first seal region 14a and the second seal region 14b are sealed by being simultaneously pressure-bonded (or adhered) based on heat and pressure by the seal tool 20.

[0075] By being sealed based on heat and pressure by the seal tool 20, the adhesive force of the second seal region 14b comes to correspond to the adhesive force of the first seal region 14a.

[0076] FIG. 6 is a diagram showing a plurality of seal regions of a battery cell of a pouch-type secondary battery according to an embodiment of the present invention. FIG. 6 shows how the battery cell 10 is viewed from above.

[0077] The battery cell 10 may include an electrode assembly 12, a pouch 11 that houses the electrode assembly 12, and an electrode lead 13 that is electrically connected to the electrode assembly 12.

[0078] A first seal region 14a may be formed in a region corresponding to the edge of the pouch 11. The first seal region 14a may be formed in the edge of the pouch 11 corresponding to the direction in which the electrode lead 13 for electrically connecting the electrode assembly 12 to the outside is located.

[0079] A second seal region 14b may be formed in a region corresponding to the edge of the electrode assembly 12. The second seal region 14b may be formed in a region corresponding to the edge of the electrode assembly 12 corresponding to the direction in which the electrode lead 13 is located.

[0080] The second seal area 14b may be an area having a shape corresponding to the shape of the edge on one side of the electrode assembly 12.

[0081] The second seal area 14b may be an area including an area corresponding to the edge of the electrode assembly 12 and a part of the packaging material area of the pouch 11. In other words, the second seal area 14b may form an area overlapping the electrode assembly 12 when viewed from above. The second seal area 14b may have an area value of 7% to 14% of the area value of the pouch 11 when viewed from above.

[0082] The area of the second seal area 14b may be larger than the area of the first seal area 14a.

[0083] The adhesive force of the second seal area 14b may correspond to the adhesive force of the first seal area 14a.

[0084] By performing sealing in a plurality of areas (for example, the first seal area 14a and the second seal area 14b), the adhesiveness of the edge of the pouch 11 of the battery cell 10 is improved, and the adhesive force between the end of the electrode 12c and the end of the separator 12d in the electrode assembly 12 is also improved.

[0085] As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the equivalent scope of the technical idea of the present invention and the appended claims by those having ordinary knowledge in the technical field to which the present invention pertains.

Claims

1. An electrode assembly in which electrodes and a separator are alternately laminated; and A pouch containing the electrode assembly and including a seal portion which is a partially joined portion, The seal portion is A first seal region formed at the edge of the pouch separated from the electrode assembly by a predetermined distance; and A second seal region which is a region corresponding to the region of the electrode assembly, The second seal region is A secondary battery having an area value of 7% to 14% of the area value of the pouch when viewed from above.

2. The second seal region is a region corresponding to the edge of the electrode assembly, The edge of the electrode assembly corresponds to the end of the electrode and the end of the separator. The secondary battery according to Claim 1.

3. The first seal region is a region corresponding to the adhesion region at the edge of the pouch, The second seal region is a region corresponding to the adhesion region at the ends of the electrodes and the ends of the separator. The secondary battery according to Claim 1.

4. The adhesive force between the end of the electrode corresponding to the electrode assembly and the end of the separator is greater than the adhesive force between the remaining portion excluding the end of the electrode and the remaining portion excluding the end of the separator. The secondary battery according to Claim 1.

5. The adhesive force of the second seal region corresponds to the adhesive force of the first seal region. The secondary battery according to Claim 1.

6. The first seal region and the second seal region are regions adhered and sealed based on heat and pressure. The secondary battery according to Claim 1.

7. The area of the second seal region is larger than the area of the first seal region. The secondary battery according to Claim 1.

8. The second seal region includes a region overlapping the electrode assembly when viewed from above. The secondary battery according to Claim 1.

9. In a sealing device for a secondary battery, A jig on which a pouch containing an electrode assembly is disposed; and A sealing tool capable of sealing a first seal region formed at the edge of the pouch and a second seal region formed in a region corresponding to the electrode assembly of the pouch, The sealing tool is Sealing the first seal region and the second seal region based on heat and pressure, The sealing tool includes an upper block and a lower block, The upper block includes a first upper block and a second upper block, The lower block includes a first lower block and a second lower block, The first upper block of the upper block and the first lower block of the lower block are formed at corresponding positions with respect to each other. The first upper block and the first lower block seal the first sealing region. In the sealing tool, The first upper block and the second upper block are integrally formed, and are a sealing device for a secondary battery.

10. In a sealing device for a secondary battery, A jig on which a pouch containing an electrode assembly is disposed; and A sealing tool capable of sealing a first sealing region formed at an edge of the pouch and a second sealing region formed in a region corresponding to the electrode assembly of the pouch, The sealing tool, Seals the first sealing region and the second sealing region based on heat and pressure. The sealing tool includes an upper block and a lower block. The upper block includes a first upper block and a second upper block. The lower block includes a first lower block and a second lower block. The first upper block and the first lower block seal the first sealing region. The second upper block and the second lower block seal the second sealing region. The second sealing region, When viewed from above, has an area value of 7% to 14% of the area value of the pouch, and is a sealing device for a secondary battery.

11. The second upper block of the upper block and the second lower block of the lower block are formed at corresponding positions with respect to each other. The second upper block and the second lower block press a part of the electrode assembly to seal the second sealing region, and the sealing device for a secondary battery according to Claim 9.

12. In a method for sealing a secondary battery, Disposing a secondary battery including a pouch containing an electrode assembly on a jig; and Using a sealing tool to seal a first sealing region formed at an edge of the pouch disposed on the jig and a second sealing region corresponding to the electrode assembly of the pouch, The step of sealing, Using the sealing tool to simultaneously seal the first sealing region and the second sealing region, and is a method for sealing a secondary battery.

13. In a method for sealing a secondary battery, Disposing a secondary battery including a pouch containing an electrode assembly on a jig; and Including a step of sealing a first seal region formed at an edge of the pouch disposed on the jig and a second seal region corresponding to the electrode assembly of the pouch using a sealing tool, The second seal region is, A sealing method for a secondary battery having an area value of 7% to 14% of the area value of the pouch when viewed from above.

14. The step of sealing is, The method for sealing a secondary battery according to claim 12 or 13, further comprising a step of sealing such that an adhesive force between an end of the electrode corresponding to the electrode assembly and an end of the separator is greater than an adhesive force between the remaining portion excluding the end of the electrode and the remaining portion excluding the end of the separator.

15. The step of sealing is, The method for sealing a secondary battery according to claim 12 or 13, further comprising a step of sealing such that the adhesive force of the second seal region corresponds to the adhesive force of the first seal region.

Images