Prismatic secondary battery including plurality of electrode assemblies

Abstract

The disclosed invention relates to a prismatic secondary battery accommodating an electrode assembly and an electrolyte within a metal case having a hexahedral shape. The electrode assembly is characterized by comprising a plurality of unit electrode assemblies stacked in the thickness direction.

Description

Square secondary battery having multiple electrode assemblies

[0001] The present invention relates to a square secondary battery, and more particularly, to a square secondary battery in which individually completed electrode assemblies capable of forming independent secondary batteries are accommodated in a single square case.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0102376, dated August 1, 2024, the entire contents of which are incorporated herein by reference.

[0003] Unlike primary batteries, secondary batteries are rechargeable and, due to their potential for miniaturization and large capacity, have been the subject of extensive research and development in recent years. With increasing technological development and demand for mobile devices, and the emergence of electric vehicles and energy storage systems in response to the era's growing environmental concerns, demand for secondary batteries as an energy source is rapidly increasing.

[0004] Secondary batteries are classified into coin-shaped, cylindrical, square, and pouch-shaped batteries, depending on the shape of their battery cases. In secondary batteries, the electrode assembly mounted inside the battery case is a rechargeable, power-generating element comprised of a laminated structure of electrodes and a separator.

[0005] Pouch-type batteries utilize a flexible laminated pouch as the battery case. The electrode assembly and electrolyte are placed inside the pouch, which is then sealed by heat-sealing the open edge. However, pouch-type batteries have limitations in their maximum thickness due to the durability of the pouch material, which limits the production of high-energy-density batteries. Furthermore, changing the shape of a mass-produced pouch-type battery requires changing the electrode shape during the electrode manufacturing and assembly processes. Furthermore, pouch-type batteries have the disadvantage of being somewhat vulnerable to cell safety issues due to gas generation during long-term use.

[0006] The purpose of the present invention is to enable the manufacture of a square battery with a metal case by utilizing an electrode assembly previously produced for the manufacture of a conventional pouch-type battery.

[0007] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0008] The present invention relates to a square secondary battery containing an electrode assembly and an electrolyte in a hexahedral metal case, wherein the electrode assembly is characterized in that a plurality of unit electrode assemblies are stacked in the thickness direction.

[0009] The above plurality of unit electrode assemblies are manufactured independently for each unit electrode assembly to form a completed power plant.

[0010] For example, each of the above unit electrode assemblies may be finished with taping or wrapping.

[0011] And, the electrode assembly is formed as a single body by having a plurality of stacked unit electrode assemblies wrapped with a separator.

[0012] The above unit electrode assembly may be a stacked cell of at least one of the S&F (Stack & Folding), L&S (Laminate & Stacking), and AZS (Advanced Zigzag Stacking) types.

[0013] In one embodiment of the present invention, the electrode assembly may be a combination of a unidirectional unit electrode assembly and a bidirectional unit electrode assembly in which the arrangement of electrode tabs is different.

[0014] In addition, each electrode tab of the unidirectional unit electrode assembly and the bidirectional unit electrode assembly can be mechanically and electrically connected to each electrode terminal provided in the square secondary battery through one current collector.

[0015] Alternatively, the electrode assembly may be a mixed unit electrode assembly having different characteristics of at least one of swelling amount, charge / discharge rate, charge / discharge capacity, capacity retention rate, and energy density.

[0016] For example, the electrode assembly may be arranged so that a unit electrode assembly having a large swelling amount is placed on the inside, and a unit electrode assembly having a relatively small swelling amount is placed on the outside to surround it.

[0017] Alternatively, the electrode assembly may be arranged so that a unit electrode assembly having a fast charge / discharge speed is placed inside, and a unit electrode assembly having a relatively slow charge / discharge speed is placed outside.

[0018] In this way, the square secondary battery of the present invention is constructed by combining multiple unit electrode assemblies, already manufactured for the production of pouch-type batteries, into a new square secondary battery. Accordingly, square secondary batteries can be efficiently produced without modifying existing pouch-type battery production lines, and production costs can be reduced by utilizing pre-manufactured electrode assemblies as is.

[0019] In addition, it is possible to mix and match unit electrode assemblies with different specifications in terms of the arrangement of electrode tabs, and furthermore, by mixing unit electrode assemblies with different swelling characteristics or charge / discharge characteristics, the performance of square secondary batteries can be improved, such as by compensating for the shortcomings of applying electrode assemblies of a single specification in the past. In particular, since such performance improvement is achieved without requiring the development of electrode assemblies with new specifications, it is also very efficient in terms of development costs.

[0020] However, the technical effects that can be obtained through the present invention are not limited to the above-described effects, and other effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0021] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0022] FIG. 1 is a drawing illustrating one embodiment of an electrode assembly accommodated in a square secondary battery of the present invention.

[0023] Figure 2 is a drawing exemplarily illustrating a configuration in which multiple unit electrode assemblies are stacked into one electrode assembly.

[0024] Figure 3 is a drawing exemplarily showing a configuration in which unit electrode assemblies with different specifications in terms of the arrangement of electrode tabs are mixed and stacked into one electrode assembly.

[0025] Fig. 4 is a drawing showing an example of configuring a square secondary battery with the electrode assembly of Fig. 3.

[0026] Figure 5 is a drawing exemplarily showing a configuration in which unit electrode assemblies having different charge / discharge characteristics, etc. are mixed and laminated into a single electrode assembly.

[0027] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail below.

[0028] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0029] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0030] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "directly above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "directly below" the other part, but also cases where there is another part in between. Furthermore, in the present application, "being placed on" may include cases where it is placed below as well as above.

[0031] The present invention relates to a square secondary battery containing an electrode assembly and an electrolyte in a hexahedral metal case, wherein the electrode assembly is characterized in that a plurality of unit electrode assemblies are laminated in the thickness direction, and each of the plurality of unit electrode assemblies is independently manufactured to form a completed state as a power generator.

[0032] In this way, the square secondary battery of the present invention is configured as a new square secondary battery by bundling a plurality of unit electrode assemblies that have already been manufactured to produce a pouch-type battery.

[0033] Accordingly, square secondary batteries can be efficiently produced without modifying the existing pouch-type battery production line, and production costs can be reduced by utilizing the already manufactured electrode assembly as is.

[0034] Hereinafter, with reference to the attached drawings, a specific embodiment of a square secondary battery (300) according to the present invention will be described in detail. For reference, the directions of front / back, up / down / left / right, etc., used to designate relative positions in the following description are intended to aid understanding of the invention, and unless otherwise specifically defined, the directions depicted in the drawings are taken as a reference.

[0035]

[0036] [First Embodiment]

[0037] FIG. 1 is a drawing illustrating one embodiment of an electrode assembly (100) accommodated in a square secondary battery (300) of the present invention. The square secondary battery (300) refers to a secondary battery in which an electrode assembly (100) and an electrolyte (340) are accommodated in a hexahedral (mostly rectangular) metal case (310). Typically, the square secondary battery (300) accommodates one electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator disposed therebetween are mutually laminated. For example, one jelly-roll electrode assembly having a size suitable for entering the accommodation space of the square case can be accommodated.

[0038] Unlike the conventional square secondary battery, in the present invention, a plurality of unit electrode assemblies (10) are stacked in the thickness direction to form one electrode assembly (100). The plurality of unit electrode assemblies (10) are independently manufactured for each unit electrode assembly (10) to form a completed power plant. For example, each unit electrode assembly (10) may be finished with taping (30) or wrapping (32), whereby each unit electrode assembly (10) may be externally and physically distinguished from each other.

[0039] Here, the meaning that each unit electrode assembly (10) is independently manufactured and completed as a power generator is in line with the fact that when the electrode assembly (100) is disassembled and divided into a plurality of unit electrode assemblies (10), an individual square secondary battery can be manufactured as the separated individual unit electrode assemblies (10). The electrode assembly (100) mounted on the square secondary battery (300) of the present invention can be used to manufacture a new high-energy density square secondary battery (300) by bundling a plurality of low-energy density unit electrode assemblies (10) that have already been produced or are being mass-produced. Furthermore, the low-energy density unit electrode assemblies (10) that have already been produced or are being mass-produced may be produced for manufacturing a secondary battery of a different specification than the square secondary battery (300), for example, a pouch-type battery.

[0040] FIG. 2 is a drawing exemplarily illustrating a configuration in which a plurality of unit electrode assemblies (10) are stacked into a single electrode assembly (100). Referring to FIG. 2, each unit electrode assembly (10) is finished with taping (30) or wrapping (32). By stacking a plurality of unit electrode assemblies (10) along the thickness direction of a square secondary battery (300) and wrapping and bundling all of the stacked unit electrode assemblies (10) together with a separator (200), a single electrode assembly (100) can be formed as an integral unit.

[0041] The unit electrode assembly (10) may be a stacked cell. For example, it may be at least one of the stacked cells of the S&F (Stack & Folding), L&S (Laminate & Stacking), and AZS (Advanced Zigzag Stacking) types. These various types of stacked cells may be formed as one type or by combining two or more types of stacked cells to form one electrode assembly (100). Here, the general structure and manufacturing method for each of the S&F, L&S, and AZS types of stacked cells are known technologies, and therefore, a detailed description thereof will be omitted herein.

[0042]

[0043] [Second Embodiment]

[0044] Fig. 3 is a drawing exemplarily showing a configuration in which unit electrode assemblies (10) having different specifications in terms of the arrangement of electrode tabs (20) are mixed and stacked into a single electrode assembly (100). Fig. 3 can be understood as an exemplary electrode assembly to show that a square secondary battery (300) of the present invention can be manufactured by combining unit electrode assemblies (10) having various specifications.

[0045] Referring to FIG. 3, the electrode assembly (100) is a mixture of a unidirectional unit electrode assembly (10") and a bidirectional unit electrode assembly (10') in which the arrangement of the electrode tabs (20) is different. Here, the unidirectional unit electrode assembly (10") refers to a structure in which a positive electrode tab (22) and a negative electrode tab (24) are arranged together on one side of the unit electrode assembly (10). On the other hand, the bidirectional unit electrode assembly (10') refers to a structure in which a positive electrode tab (22) and a negative electrode tab (24) are separated and arranged separately on opposite sides of the unit electrode assembly (10). In FIG. 3, the unidirectional unit electrode assembly (10") has a positive electrode tab (22) and a negative electrode tab (24) protruding toward the upper side (based on the drawing), and the bidirectional unit electrode assembly (10') is divided into left and right sides (based on the drawing) and has a positive electrode tab (22) and a negative electrode tab (24) protruding.

[0046] FIG. 4 is a drawing illustrating an example of configuring a square secondary battery (300) with the electrode assembly (100) of FIG. 3. The electrode assembly (100) of FIG. 3 has a positive electrode tab (22) and a negative electrode tab (24) of a one-way unit electrode assembly (10") spaced apart from each other on the upper surface, and a positive electrode tab (22) and a negative electrode tab (24) of a two-way unit electrode assembly (10') arranged on both sides.

[0047] For the simplification of the structure, each electrode tab (22, 24) of the unidirectional unit electrode assembly (10") and the bidirectional unit electrode assembly (10') is mechanically and electrically connected to each electrode terminal (320) provided in the square secondary battery (300) through one current collector (330). To this end, the positive electrode tab (22) of the unidirectional unit electrode assembly (10") is arranged in a direction close to the positive electrode tab (22) of the bidirectional unit electrode assembly (10'), and the negative electrode tab (24) of each unit electrode assembly (10', 10") is also arranged in the same direction.

[0048] And, FIGS. 1 and 2 show an example of a case where a plurality of bidirectional unit electrode assemblies are applied as a unit electrode assembly (10) of the same specification in which the arrangement of electrode tabs (20) is the same. Although not illustrated in the drawing, it will be clearly understood that it is also possible to construct an electrode assembly (100) by stacking a plurality of unidirectional unit electrode assemblies.

[0049]

[0050] [Embodiment 3]

[0051] FIG. 5 is a drawing exemplarily showing a configuration in which unit electrode assemblies (10', 10") having different charge / discharge characteristics, etc. are mixed and stacked into one electrode assembly (100).

[0052] Each unit electrode assembly (10', 10") has differences in its behavior and main performance indicators in terms of charge / discharge characteristics depending on the main components (series) of the positive and negative electrode materials.

[0053] For example, there may be differences in the amount of swelling that occurs when a unit electrode assembly expands during charge and discharge. Specifically, using a silicon-based anode material is advantageous for rapid charge and discharge, but the amount of swelling may increase depending on the silicon content.

[0054] Alternatively, capacity retention, which measures the rate of decrease in discharge capacity relative to the initial value after multiple charge / discharge cycles (e.g., 200 charge / discharge cycles), may also vary across individual electrode assemblies. For example, the NCM 622 series cathode material is stable and has excellent capacity retention, but is expensive.

[0055] Charge-discharge characteristics can be evaluated not only by swelling amount, charge-discharge speed, and capacity retention rate, but also by charge-discharge capacity, energy density, etc., and these various charge-discharge characteristics exhibit various aspects depending on the series of positive and negative electrode materials used in the unit electrode assembly. Another advantage of the present invention is that by mixing unit electrode assemblies with these various charge-discharge characteristics, a new electrode assembly close to the target characteristics can be created without developing new positive and negative electrode materials. For example, development of a new positive electrode material combining LMFP and NCM is being attempted, but when combining positive electrode materials of different series, various problems may arise in electrode production. Therefore, instead of combining positive electrode materials of different series themselves, one way to solve these problems is to mix already verified unit electrode assemblies containing each positive electrode material to create a single electrode assembly.

[0056] In addition, even when unit electrode assemblies (10', 10") having different charge / discharge characteristics are mixed and stacked into a single electrode assembly (100), it may be desirable to optimize the stacking order or structure. For example, an electrode assembly (100) having a sandwich structure in which a unit electrode assembly (10") having a large swelling amount is placed on the inside and a unit electrode assembly (10') having a relatively small swelling amount is wrapped around it can be stacked. By creating a structure in which the unit electrode assembly (10") having a large swelling amount is pressed, the swelling amount of the electrode assembly (100) itself can be appropriately controlled.

[0057] Alternatively, the electrode assembly (100) may be manufactured in a structure in which a unit electrode assembly (10") having a fast charge / discharge speed is placed on the inside, and a unit electrode assembly (10') having a relatively slow charge / discharge speed is wrapped around it. This is because the unit electrode assembly (10") having a fast charge / discharge speed generally has a large amount of swelling. In addition, since the unit electrode assembly (10") having a fast charge / discharge speed usually has a larger temperature rise during charge / discharge, the influence of the heat generated in the electrode assembly (100) on the surroundings can be reduced by placing the unit electrode assembly (10') having a relatively low temperature on the outside.

[0058]

[0059] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0060] [Explanation of symbols]

[0061] 10, 10', 10": Unit electrode assembly

[0062] 20: Electrode tab

[0063] 22: Positive tab

[0064] 24: Negative tab

[0065] 30: Taping

[0066] 32: Wrapping

[0067] 100: Electrode assembly

[0068] 200: Membrane

[0069] 300: Square secondary battery

[0070] 310: Case

[0071] 320: Electrode terminal

[0072] 330: Whole house

[0073] 340: Electrolyte

Claims

1. In a square secondary battery containing an electrode assembly and an electrolyte in a hexahedral metal case, The above electrode assembly is a square secondary battery in which a plurality of unit electrode assemblies are stacked in the thickness direction.

2. In paragraph 1, The above multiple unit electrode assemblies are, A square secondary battery in which each unit electrode assembly is manufactured independently to form a completed power plant.

3. In paragraph 2, A square secondary battery, each of the above unit electrode assemblies finished with taping or wrapping.

4. In paragraph 3, The above electrode assembly, A square secondary battery in which multiple stacked unit electrode assemblies are formed into a single body by being wrapped with a separator.

5. In any one of paragraphs 1 to 4, The above unit electrode assembly is, A square secondary battery having at least one stacked cell among the S&F (Stack & Folding), L&S (Laminate & Stacking), and AZS (Advanced Zigzag Stacking) types.

6. In any one of paragraphs 1 to 4, The above electrode assembly, A square secondary battery in which a unidirectional unit electrode assembly and a bidirectional unit electrode assembly with different arrangements of electrode tabs are mixed.

7. In paragraph 6, Each electrode tab of the above unidirectional unit electrode assembly and bidirectional unit electrode assembly, A square secondary battery, wherein each electrode terminal provided in the square secondary battery is mechanically and electrically connected through a single current collector.

8. In any one of paragraphs 1 to 4, The above electrode assembly, A square secondary battery in which unit electrode assemblies having different characteristics of at least one of swelling amount, charge / discharge rate, charge / discharge capacity, capacity retention rate, and energy density are mixed.

9. In paragraph 8, The above electrode assembly, A square secondary battery in which a unit electrode assembly having a large swelling amount is placed on the inside and a unit electrode assembly having a relatively small swelling amount is placed on the outside to surround it.

10. In paragraph 8, The above electrode assembly, A square secondary battery in which a unit electrode assembly with a fast charge / discharge speed is placed on the inside and a unit electrode assembly with a relatively slow charge / discharge speed is placed on the outside to surround it.

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