Secondary battery module

Abstract

The present invention provides a secondary battery module comprising a secondary battery stack having stacked therein a plurality of secondary batteries each having two long sides and two short sides connecting both ends of the long sides, respectively, the secondary battery module comprising a foam pad inserted between adjacent secondary batteries in the secondary battery stack, wherein the foam pad includes: a body made of a flexible material and having an accommodation part which is a sealed space formed therein; and a working fluid injected into the accommodation part, the deformation of the accommodation part occurs by the pressure acting on the secondary batteries and the flow of the working fluid occurs in the accommodation part.

Description

secondary battery module

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0116625, filed August 29, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery module, and more particularly, to a secondary battery module including a foam pad that can apply a constant surface pressure to a short side of a secondary battery by being deformed to fit the shape of the swollen secondary battery even when swelling occurs in the secondary battery included in the secondary battery stack.

[0003]

[0004] Demand for high-efficiency secondary batteries is rapidly increasing in industries such as mobile devices and electric vehicles. Among these secondary batteries, lithium secondary batteries, with their high energy density, ability to sustain relatively high voltages, and low self-discharge rates, are commercialized and widely used, and active research and development is underway to improve their performance.

[0005] Secondary batteries have a structure in which an electrode assembly and electrolyte are embedded in a case such as a can or pouch.

[0006] Among these, the pouch-type secondary battery has a structure in which an electrode assembly is mounted within a pouch. At this time, the electrode assembly has a structure in which a positive electrode, a separator, and a negative electrode are repeatedly laminated, and the positive electrode tabs extending from each positive electrode are gathered into one and connected to a positive electrode lead (an electrode lead having a positive pole), and the negative electrode tabs extending from each negative electrode are gathered into one and connected to a negative electrode lead (an electrode lead having a negative pole). In addition, the ends of the positive electrode lead and the negative electrode lead protrude from the pouch so as to be electrically connected to the outside.

[0007] Meanwhile, secondary batteries installed in vehicles, ESS (Energy Storage Systems), etc. are combined in multiples to form secondary battery modules to increase output and electrical storage capacity, and multiple secondary battery modules are combined to form secondary battery packs. In other words, multiple secondary batteries are assembled into a secondary battery module, and multiple secondary battery modules are assembled into a secondary battery pack, which is then installed in vehicles, ESS, etc.

[0008] When the above pouch-type secondary battery is manufactured as a secondary battery module, the secondary batteries are provided as a secondary battery laminate (10) in a state where their flat surfaces are stacked so that they are in contact with each other.

[0009] In addition, in order to absorb the shrinkage and expansion of the secondary batteries (1) in the secondary battery stack (10) and reduce heat generation, a foam pad (2) is additionally provided between adjacent secondary batteries (1).

[0010] Referring to FIG. 1A, which illustrates the appearance of a secondary battery module (100) and the appearance of a secondary battery stack (10) formed by stacking secondary batteries (1) and foam pads (2) by removing external frames from the secondary battery module (100), the secondary battery stack (10) is housed within frames that cover external surfaces so as to be protected from external impact, and each of the positive electrode lead (1a) and the negative electrode lead (1b) of the secondary batteries (1) is configured to be electrically connected to the outside by being connected to a bus bar mounted on a bus bar assembly coupled to the frame.

[0011] At this time, a foam pad (2) is inserted between the secondary batteries (1) to absorb the volume change due to shrinkage and expansion of the secondary batteries (1).

[0012] That is, the secondary battery stack (10) experiences temperature changes, mechanical loads, shocks, and vibrations depending on the environment in which it is mounted. The foam pad (2) is provided to protect the secondary battery (1) from such external factors, and one, two, or more secondary batteries (1) are stacked between adjacent foam pads (2).

[0013] And, such a pouch-type secondary battery (1) is typically manufactured to have a rectangular plate shape. That is, it is manufactured so that two long sides (l) and two short sides (s) connecting the ends of both sides of the long sides (l) are formed (see Fig. 2), and the foam pad (2) is also manufactured so that two long sides (l) and two short sides (s) connecting the ends of both sides of the long sides (l) are formed to suit the shape and size of such a secondary battery.

[0014] Meanwhile, the secondary battery (1) had a problem in that as repeated charging and discharging was performed, the electrolyte could evaporate, and as a result, gas was generated inside the pouch, causing the pouch to swell, resulting in a swelling phenomenon.

[0015] That is, the appearance before swelling occurs when conventional foam pads are laminated. And what it looks like after swelling occurs Referring to this illustrated drawing 1b, before swelling occurred in the secondary battery (1), the conventional foam pad (2) was able to evenly apply surface pressure to the entire secondary battery, but when swelling occurred in the secondary battery (1) and the central portion swelled, there was a problem in that an appropriate surface pressure could not be applied to the short side (s) of the secondary battery (1).

[0016] This pressure difference could be a cause of lithium precipitation within the secondary battery. More specifically, when the surface pressure at the short side (s) of the secondary battery (1) decreases and pressure imbalance occurs, a microscopic residual gas trap or local pressurization occurs within the secondary battery (1), resulting in a resistance difference within the electrode assembly, and this resistance difference has the problem of lithium precipitation. In other words, the lower the resistance difference, the lower the possibility of lithium precipitation.

[0017] Therefore, in order to solve this problem, a foam pad was required that could solve the problem of surface pressure imbalance by providing sufficient surface pressure even at the short side (s) where the electrode leads (1a, 1b) protrude, even if the thickness of the secondary battery (1) becomes uneven (due to swelling or other reasons).

[0018]

[0019] Accordingly, the main purpose of the present invention is to provide a secondary battery module including a foam pad that can solve the problem of pressure imbalance applied to a secondary battery by applying appropriate surface pressure to a short side of the secondary battery even when swelling of the secondary battery occurs.

[0020]

[0021] In order to achieve the above-described object, the present invention provides a secondary battery module including a secondary battery stack in which a plurality of secondary batteries are stacked, each of which has two long sides and two short sides connecting both ends of the long sides, and a foam pad inserted between adjacent secondary batteries in the secondary battery stack, wherein the foam pad includes a body made of a flexible material and having a receiving portion, which is a sealed space, formed therein; and a working fluid injected into the receiving portion, wherein the receiving portion is deformed by pressure applied from the secondary battery and the working fluid flows within the receiving portion. That is, when a higher pressure is applied to a part of the receiving portion so that the space is reduced and deformed, another part within the receiving portion is deformed so that the space is increased, and the working fluid moves there (the point where the space is increased).

[0022] The above working fluid is provided as any one selected from among a liquid, a gas, and a semi-solid having fluidity.

[0023] At this time, the working fluid may be a mixture of two or more of a liquid, a gas, or a semi-solid having fluidity.

[0024] The above body is made of an insulating film having electrical insulation properties. More specifically, the body is made of an insulating film having a thickness in the range of 10 μm to 100 μm and having electrical non-conductivity.

[0025] The above body is formed in a shape having two long sides and two short sides connecting the ends of the two long sides, respectively. That is, the body may have a rectangular shape.

[0026] When swelling occurs in a neighboring secondary battery, the central portion of the body is deformed so that the thickness decreases relatively along the longitudinal direction and the thickness increases relatively toward the ends of the body. Here, the thickness refers to the length in the stacking direction in which the secondary battery and the foam pad are stacked, which is the vertical direction based on FIGS. 3 and 5.

[0027] A reinforcing member made of a material having higher rigidity than the material of the body is attached to the outer side of the above-mentioned short side.

[0028] In addition, the body of the foam pad provided in the present invention may be configured to have a smaller deformation amount as it goes outward from the central portion. That is, the body may be manufactured to have the smallest stiffness (or density) in a region including the central portion, which is the midpoint between the short sides on both sides, and may be configured to have a smaller deformation amount gradually or stepwise as it approaches the short sides on both sides. That is, the stiffness mentioned here may mean the degree to which it resists deformation when an external force is applied, and a large stiffness may mean a small deformation amount, and a small stiffness may mean a large deformation amount.

[0029] Referring to FIG. 6, the body includes a first region including a central point between short sides; a second region positioned so as to extend outwardly from the first region along the long side; and a third region positioned so as to extend outwardly from the second region along the long side and including the short side; and the body is manufactured to have higher rigidity in the second region than in the first region and to have higher rigidity in the third region than in the second region.

[0030] That is, in the present invention, the body may include at least three regions (first region, second region, third region) formed with different rigidities.

[0031] In the above secondary battery stack, the foam pad can be inserted only into a pre-selected location between adjacent secondary batteries.

[0032] Alternatively, in the secondary battery stack, the foam pad may be inserted between every adjacent secondary battery.

[0033] In addition, the present invention additionally provides a secondary battery pack in which a plurality of secondary battery modules having the above-described technical characteristics are combined.

[0034]

[0035] The secondary battery module of the present invention having the above technical features can apply an appropriate surface pressure to the short side of the secondary battery facing it by changing the shape of the body (due to the flow of the working fluid injected into the receiving portion) according to the pressure applied to the secondary battery. In other words, the pressure imbalance problem occurring in the conventional foam pad structure can be resolved.

[0036] The foam pad of this invention has a reinforcing member made of a material having higher rigidity than the material of the body attached to the outer side of the short side of the body, thereby preventing the body from protruding in an unnecessary direction or being deformed into an unnecessary shape.

[0037]

[0038] Figure 1a is a drawing showing the appearance of a secondary battery module and the appearance of a secondary battery stack formed by stacking secondary batteries and foam pads by removing external frames from the secondary battery module.

[0039] Figure 1b shows the appearance before swelling occurs when conventional foam pads are laminated. And what it looks like after swelling occurs This drawing is shown.

[0040] Figure 2 is a drawing showing the appearance of a secondary battery included in a secondary battery module of the present invention.

[0041] FIG. 3 is a drawing showing a portion of a secondary battery stack of the present invention, in which a foam pad is inserted between secondary batteries.

[0042] Fig. 4 is a drawing partially showing the appearance of the foam pad provided in the present invention.

[0043] Figure 5 is a drawing showing the deformation of the foam pad when swelling occurs in a secondary battery, showing the appearance when the reinforcing part is not bonded (top) and the appearance when the reinforcing part is bonded (bottom).

[0044] Figure 6 is a drawing showing three areas formed with different rigidities in the body of the foam pad.

[0045]

[0046] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0047] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0048] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0049] The present invention relates to a secondary battery module including a foam pad that can apply an appropriate surface pressure (pressure applied to a contact surface) to a short side of a secondary battery even when swelling of the secondary battery occurs. Hereinafter, preferred embodiments provided by the present invention will be described in more detail with reference to the attached drawings.

[0050] FIG. 2 is a drawing showing the appearance of a secondary battery included in a secondary battery module of the present invention, and FIG. 3 is a drawing showing a part of a secondary battery stack of the present invention, in which a foam pad is inserted between secondary batteries. In addition, FIG. 4 is a drawing partially transparently showing the appearance of a foam pad provided by the present invention, and FIG. 5 is a drawing showing the appearance of a foam pad deformed when swelling occurs in a secondary battery, showing the appearance when a reinforcing part is not bonded (top) and the appearance when a reinforcing part is bonded (bottom). For reference, FIG. 5 is a drawing showing a state in which swelling occurs in a secondary battery to clearly show the appearance of the foam pad of the present invention being deformed. In addition, FIG. 6 is a drawing showing three regions having different rigidities formed in the body of a foam pad.

[0051] The secondary battery module provided in the present invention includes a secondary battery stack (10: see Fig. 1a) in which secondary batteries (1) are stacked so that their flat surfaces are in contact with each other, similar to a conventional structure. In addition, a foam pad (20) is additionally provided between adjacent secondary batteries (1) in the secondary battery stack to absorb shrinkage and expansion of the secondary batteries (1) and reduce heat generation.

[0052] The secondary battery (1) provided in the present invention is a pouch-type secondary battery, and is manufactured to have a rectangular plate shape, as illustrated in FIG. 2. That is, it is manufactured to have two long sides (l) and two short sides (s) that connect the ends of the long sides (l), respectively, and, in accordance with the shape and size of the secondary battery, the foam pad (20) is also manufactured to have two long sides (l) and two short sides (s) that connect the ends of the long sides (l), respectively, as illustrated in FIGS. 3 and 4.

[0053] The above foam pad (20) may have a length equal to or shorter than that of the secondary battery (1), but as illustrated in FIG. 3, it is preferable to have a length longer than the secondary battery (1) (so that it can protrude a predetermined length from each end of the secondary battery). In the secondary battery stack (10), the foam pad (20) is arranged to be inserted between adjacent secondary batteries (1), and may be configured such that one or more secondary batteries are arranged between adjacent foam pads.

[0054] Referring to FIG. 4, the foam pad (20) provided in the embodiment of the present invention is configured to include a body (21) and an operating fluid (23).

[0055] The above body (21) can be manufactured from a material having flexibility, such as silicone, synthetic rubber, film, or other types of thin film materials, and a receiving portion (22), which is a sealed space, is formed inside.

[0056] The material from which the body (21) is manufactured is selected from materials that do not have electrical conductivity. For example, the body provided in this embodiment is manufactured from an insulating film having electrical insulation properties. More specifically, the body (21) is manufactured from an insulating film having a thickness in the range of 10 μm to 100 μm. The body (21) is manufactured to have the same thickness overall, but may be manufactured to have different thicknesses in parts in order to suppress the size of protrusion to the outside (left and right directions based on FIG. 5) when the working fluid (23) is concentrated on the short side (s) (see the upper drawing of FIG. 5).

[0057] That is, the body (21) has a size and shape that can be inserted between secondary batteries (1), but is an empty structure with a space formed inside, and the space is defined as a receiving portion (22) in the present invention.

[0058] And, a working fluid (23) is injected into the receiving portion (22). The working fluid (23) is provided as any one selected from among a liquid, a gas, and a semi-solid having fluidity. At this time, the working fluid (23) may be a mixture of two or more of a liquid, a gas, and a semi-solid having fluidity.

[0059] The above-mentioned working fluid (23) is preferably selected from among incompressible fluids that have the property of having a volume that hardly changes depending on pressure. That is, in the case of a compressible fluid, when the middle part of the body (21) is pressed, the body may be compressed without expanding at the short side (s) (up and down based on FIG. 5) as shown in the upper drawing of FIG. 5. Therefore, the working fluid (23) is preferably selected from among incompressible fluids, although there is no particular limitation on the type.

[0060] The foam pad (20) configured as above causes deformation of the receiving portion (22) due to the pressure applied from the secondary battery (1) (pressure generated by deformation of the secondary battery), and thus causes the flow of the working fluid (23) within the receiving portion (22). For example, as illustrated in FIG. 5, when swelling occurs in the secondary battery (1) and pressure is applied to the middle portion of the body (21), the central portion of the body (21) is deformed in a direction in which the thickness decreases due to the pressure, and thus the working fluid (23) flows to the short sides (s) located at both ends of the body (21). In addition, as illustrated, the short sides (s) of the body (21) are deformed to expand in the vertical direction as the working fluid (23) is gathered therein.

[0061] Accordingly, when swelling occurs in at least one of the neighboring secondary batteries (1), the central portion of the body (21) along the longitudinal direction is deformed so that the thickness relatively decreases and the thickness relatively increases toward the end of the body (21), so that the body (21) can also apply an appropriate surface pressure to the short side portion (s) of the secondary battery (1).

[0062] In addition, a reinforcing member (24) made of a material having a higher rigidity than the material of the body (21) may be optionally attached to the outside of the short side (s) of the body (21). That is, as illustrated in FIGS. 4 and 5, the reinforcing member (24) is attached to the short side (s) of the body (21) to minimize the body (21) from protruding in an unnecessary direction (left-right direction based on FIG. 5) and to be deformed to expand in a direction that forms a surface pressure on the secondary battery (up-down direction based on FIG. 5). Therefore, it is preferable that the reinforcing member (24) be manufactured so that bending is minimized and elongation is possible in the longitudinal direction (up-down direction based on FIG. 5).

[0063] In addition, the body (21) of the foam pad (20) provided in the present invention can be configured so that the deformation amount decreases as it goes outward from the central portion so as to more efficiently support the short side portion (s).

[0064] That is, the body (21) may be manufactured to have the smallest stiffness (or density) in a region including the central portion, which is the midpoint between the short sides (s) on both sides, so that the deformation gradually or stepwise decreases as it approaches the short sides (s) on both sides. In addition, the stiffness mentioned here may mean the degree to which it resists deformation when an external force is applied, and a high stiffness may mean a small deformation, and a low stiffness may mean a large deformation.

[0065] Referring to FIG. 6, the body (21) includes a first region (Z1) including a central point between short sides (s); a second region (Z2) positioned so as to extend outwardly from the first region (Z1) along the long side (l); and a third region (Z3) positioned so as to extend outwardly from the second region (Z2) along the long side (l) and including the short side (s); and the body (21) is manufactured to have higher rigidity in the second region (Z2) than in the first region (Z1) and to have higher rigidity in the third region (Z3) than in the second region (Z2).

[0066] That is, in the present invention, the body may include at least a first region (Z1), a second region (Z2), and a third region (Z3) formed with different rigidities.

[0067] In addition, a body (21) having different rigidity in each of multiple areas can be manufactured through a known method of integrally molding materials with different properties, such as multi-component molding.

[0068] Meanwhile, in the secondary battery stack (10), the foam pad (20) can be inserted only into a pre-selected location between adjacent secondary batteries (1). Alternatively, in the secondary battery stack (10), the foam pad (20) can be inserted into every space between adjacent secondary batteries.

[0069] In addition, the present invention additionally provides a secondary battery pack in which a plurality of secondary battery modules having the above-described technical characteristics are combined.

[0070] The secondary battery module of the present invention having the above technical features can apply an appropriate surface pressure to the short side of the secondary battery facing it by changing the shape of the body (due to the flow of the working fluid injected into the receiving portion) according to the pressure applied to the secondary battery. In other words, the pressure imbalance problem occurring in the conventional foam pad structure can be resolved.

[0071] The foam pad of this invention has a reinforcing member made of a material having higher rigidity than the material of the body attached to the outer side of the short side of the body, thereby preventing the body from protruding in an unnecessary direction or being deformed into an unnecessary shape.

[0072] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0073]

[0074] [Explanation of symbols]

[0075] 1: Secondary battery

[0076] 10: Secondary battery stack

[0077] 20: Foam pad

[0078] 21: Body

[0079] 22: Reception area

[0080] 23: Working fluid

[0081] 24: Reinforcement

Claims

1. A secondary battery module including a secondary battery stack in which a plurality of secondary batteries are stacked, each of which has two long sides and two short sides connecting the ends of the long sides, respectively. A foam pad inserted between adjacent secondary batteries in the secondary battery stack; The above foam pad is, A body manufactured from a flexible material and having a sealed space, which is a receiving portion, formed therein; and a working fluid injected into the receiving portion; A secondary battery module in which deformation of the receiving portion occurs due to pressure applied from the secondary battery and a flow of working fluid occurs within the receiving portion.

2. In paragraph 1, The above working fluid is, A secondary battery module selected from among liquid, gas, and semi-solid with fluidity.

3. In paragraph 2, The above working fluid is, A secondary battery module in which two or more of liquid, gas, and fluid semi-solid are mixed.

4. In paragraph 1, The above body is a secondary battery module manufactured with an insulating film having electrical insulation properties.

5. In paragraph 4, The above body is a secondary battery module manufactured with an insulating film having a thickness in the range of 10㎛ to 100㎛.

6. In paragraph 1, The above body is a secondary battery module formed in a shape having two long sides and two short sides connecting the ends of the two long sides, respectively.

7. In paragraph 6, A secondary battery module that, when swelling occurs in a neighboring secondary battery, deforms such that the central portion of the body along the longitudinal direction relatively decreases in thickness and the thickness relatively increases toward the ends of the body.

8. In paragraph 7, A secondary battery module having a reinforcing member made of a material having higher rigidity than the material of the body attached to the outer side of the above-mentioned short side.

9. In paragraph 7, The above body, A first region including the central point between the short sides; A second region positioned so as to extend outward from the first region along the longitudinal side; and A third region is positioned so as to extend to the outside of the second region along the long side and includes a short side; A secondary battery module manufactured so that the above body has higher rigidity in the second region than in the first region and higher rigidity in the third region than in the second region.

10. In any one of paragraphs 1 to 9, A secondary battery module in which the foam pad is inserted only into a pre-selected location between adjacent secondary batteries in the secondary battery stack.

11. In any one of paragraphs 1 to 9, In the above secondary battery stack, the foam pad is a secondary battery module inserted between every adjacent secondary battery.

12. A secondary battery pack comprising a plurality of secondary battery modules according to any one of claims 1 to 9.

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