Battery module having a pad composite with swelling absorption and heat shielding functions, battery pack and automobile including the same

Abstract

To provide a battery module having a structure capable of absorbing volume expansion caused by swelling of a battery cell, maintaining a gap between adjacent battery cells constantly even if a temperature in the battery module rises above a critical value due to abnormal heating generated in some battery cells, and delaying propagation of thermal runaway between adjacent battery cells.SOLUTION: A battery module includes: a cell stack including a plurality of battery cells and at least one pad composite interposed between neighboring battery cells; and a module case configured to accommodate the cell stack. The pad composite includes a pair of swelling absorption pads compressed according to volume expansion of the battery cell caused by swelling; and a heat shielding pad interposed between the pair of swelling absorption pads to block heat transfer between the neighboring battery cells and configured to expand at a preset reference temperature or above.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a battery module including a pad composite having swelling absorption and heat shielding functions, and a battery pack and an automobile including the same. More specifically, the present invention relates to a battery module to which a pad composite including a swelling absorbing pad that is compressed due to expansion of a battery cell due to swelling, and a heat shielding pad that expands and fills a space previously occupied by the swelling absorbing pad when the swelling absorbing pad is damaged due to an increase in internal temperature of the battery module, and a battery pack and an automobile including the same are applied.

[0002] This application claims priority to Korean Patent Application No. 10-2019-0024840, filed on March 4, 2019, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] Generally, a battery module is equipped with a cooling system to prevent the lifespan of the battery module from being rapidly shortened due to temperature during long-term use, and such a cooling system is designed taking into account the amount of heat generated by the battery module due to its usage environment.

[0004] However, if some battery cells fail and generate abnormal heat during use of the battery module, the temperature will continue to rise and exceed the critical temperature, which can cause thermal runaway and lead to safety issues.

[0005] That is, if a thermal runaway that occurs in some battery cells spreads to adjacent battery cells in a short time, the temperature of the entire battery module rises rapidly, which leads to an increase in the temperature of the entire battery pack including a plurality of battery modules, which may cause great damage to property and human life. Therefore, in order to prevent such a rapid spread of the thermal runaway phenomenon, it is necessary to apply a thermal insulating member between adjacent battery cells.

[0006] In addition, a buffer member capable of absorbing swelling by being compressed due to expansion of the battery cells caused by swelling is applied between adjacent battery cells. As the buffer member, an expanded polyproyhylene (EPP) pad or a urethane pad may be used.

[0007] A buffer pad made of such a material has a certain level of elasticity during normal use of the battery module, and is compressed when the battery cells expand due to swelling to absorb the swelling. It also maintains the distance between adjacent battery cells, thereby delaying heat transfer between adjacent battery cells in the event of abnormal heat generation.

[0008] However, buffer pads made of such materials are susceptible to damage and may shrink if a thermal runaway phenomenon occurs in some battery cells and the temperature inside the battery module exceeds a critical value.

[0009] In this manner, if the buffer pad is damaged by heat and shrinks, the distance between adjacent battery cells via the buffer pad may decrease, and the propagation speed of the thermal runaway phenomenon between the adjacent battery cells may become faster.

[0010] Therefore, there is a need to develop a battery module having a structure that can absorb volume expansion due to swelling of the battery cells, maintain a constant distance between adjacent battery cells even if the temperature inside the battery module rises above a critical value due to abnormal heat generated in some battery cells, and delay the propagation of thermal runaway between adjacent battery cells. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above problems, and has an object to provide a battery module having a structure that can absorb volume expansion due to swelling of battery cells, maintain a constant distance between adjacent battery cells even if the temperature inside the battery module rises above a critical value due to abnormal heat generated in some battery cells, and delay the propagation of a thermal runaway phenomenon between adjacent battery cells.

[0012] The technical problems to be solved by the present invention are not limited to the above problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0013] In order to solve the above-mentioned problems, a battery module according to one aspect of the present invention includes a cell stack including a plurality of battery cells and at least one pad composite interposed between adjacent battery cells, and a module case that accommodates the cell stack, and the pad composite includes a pair of swelling absorption pads that are compressed due to volumetric expansion caused by swelling of the battery cells, and a heat blocking pad that is interposed between the pair of swelling absorption pads to block heat transfer between adjacent battery cells and expands at a preset reference temperature or higher.

[0014] The swelling absorbent pad may shrink and reduce in thickness at or above the reference temperature.

[0015] The thermal barrier pad may expand above the reference temperature to fill the space created by the contraction of the swelling absorbing pad.

[0016] The thermal insulating pad may have a thicknesswise expansion coefficient of 5 to 40 at or above the reference temperature.

[0017] The battery cell may be a pouch-type battery cell.

[0018] One pad complex may be provided, and the one pad complex may be disposed at the center in the stacking direction of the cell stack.

[0019] The battery module may further include a plurality of swelling absorbing pads disposed between each of the cell groups including a plurality of battery cells.

[0020] A plurality of the pad complexes may be provided, and the plurality of pad complexes may be disposed between each of the cell groups including a plurality of battery cells.

[0021] The swelling absorbent pad may include at least one of EPP and urethane.

[0022] The heat insulating pad may include at least one of an epoxy resin, a butyl resin, and a polyvinyl chloride resin.

[0023] Meanwhile, a battery pack and a vehicle according to another aspect of the present invention include the battery module according to the aspect of the present invention as described above. Effect of the Invention

[0024] According to one aspect of the present invention, it is possible to provide a battery module that can absorb volume expansion due to swelling of battery cells, maintain a constant distance between adjacent battery cells even if the temperature inside the battery module rises above a critical value due to abnormal heat generated in some battery cells, and delay the propagation of a thermal runaway phenomenon between adjacent battery cells.

[0025] The following drawings attached to this specification are illustrative of preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings. [Brief description of the drawings]

[0026] [Figure 1] 1 is a perspective view showing a battery module according to an embodiment of the present invention; [Diagram 2] 1 is a diagram illustrating a battery cell applied to a battery module according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating a cell stack applied to a battery module according to an embodiment of the present invention, in which the internal temperature of the battery module is lower than a reference temperature. [Figure 4] FIG. 2 is a diagram illustrating a cell stack applied to a battery module according to an embodiment of the present invention, in which the internal temperature of the battery module is equal to or higher than a reference temperature. [Diagram 5] FIG. 13 is a diagram illustrating a cell stack applied to a battery module according to another embodiment of the present invention. [Figure 6] FIG. 13 is a diagram showing a cell stack applied to a battery module according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the present specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as being in accordance with the meaning and concept of the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concept of the term in order to best describe the invention. Therefore, it should be understood that the embodiment described in this specification and the configuration shown in the drawings are merely the most preferred embodiment of the present invention, and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0028] First, a battery module according to one embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.

[0029] Fig. 1 is a perspective view showing a battery module according to an embodiment of the present invention, Fig. 2 is a view showing a battery cell applied to the battery module according to an embodiment of the present invention, Fig. 3 is a view showing a cell stack applied to the battery module according to an embodiment of the present invention, illustrating a case where the internal temperature of the battery module is lower than a reference temperature, and Fig. 4 is a view showing a cell stack applied to the battery module according to an embodiment of the present invention, illustrating a case where the internal temperature of the battery module is equal to or higher than a reference temperature.

[0030] 1 to 4, a battery module according to an embodiment of the present invention includes a cell stack 100 and a module case 200 that houses the cell stack 100. The cell stack 100 includes a plurality of battery cells 110 and at least one pad complex 120 interposed between adjacent battery cells 110.

[0031] For example, a pouch-type battery cell may be applied as the battery cell 110. When the battery cell 110 is a pouch-type battery cell, the battery cell 110 may be embodied in a form including an electrode assembly (not shown), a pouch case 111, an electrode lead 112, and a sealing tape 113, as shown in FIG.

[0032] Although not shown, the electrode assembly has a form in which a separator is interposed between positive and negative electrode plates that are alternately stacked, and it is preferable that a separator is located at the outermost edge of each side for insulation.

[0033] The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer coated on one side thereof. A positive electrode uncoated region is formed at one end of the positive electrode current collector where the positive electrode active material is not coated, and the positive electrode uncoated region functions as a positive electrode tab.

[0034] The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector. A negative electrode uncoated region that is not coated with the negative electrode active material is formed at one end of the negative electrode current collector, and the negative electrode uncoated region functions as a negative electrode tab.

[0035] In addition, the separator is interposed between the positive and negative electrode plates to prevent direct contact between the electrode plates having opposite polarities, and may be made of a porous material to allow ion movement between the positive and negative electrode plates using the electrolyte as a medium.

[0036] The cell case 111 includes a receiving portion 111a for receiving an electrode assembly, and a sealing portion 111b extending in a peripheral direction of the receiving portion 111a and sealing the cell case 111 by being heat-sealed with the electrode lead 112 being pulled out to the outside.

[0037] Although not shown, the cell case 111 is sealed by abutting and heat-sealing the peripheral portions of an upper case and a lower case made of a multi-layer pouch film in which a resin layer / metal layer / resin layer are laminated in sequence.

[0038] The pair of electrode leads 112 are connected to a positive electrode tab (not shown) and a negative electrode tab (not shown), respectively, and are drawn out to the outside of the cell case 111. The pair of electrode leads 112 are drawn out in parallel to one side in the longitudinal direction of the battery cell 110, or drawn out to one side and the other side in the longitudinal direction of the battery cell 110, respectively. That is, the battery cell 110 applied to the present invention may be a one-way draw-out type battery cell in which the positive electrode lead and the negative electrode lead are drawn out in the same direction, or may be a two-way draw-out type battery cell in which the positive electrode lead and the negative electrode lead are drawn out in opposite directions.

[0039] The sealing tape 113 is attached around the electrode lead 112 and is interposed between the inner surface of the sealing part 111b of the pouch case 111 and the electrode lead 112. The sealing tape 113 prevents deterioration of the sealing property of the sealing part 111b due to the electrode lead 112 being pulled out.

[0040] The pad complex 120 is interposed between adjacent battery cells 110, and only one may be provided to minimize an increase in thickness of the cell stack 100. When one pad complex 120 is provided, it is preferable that the pad complex 120 is disposed at the center in the stacking direction of the cell stack 100. This is to efficiently block the propagation of a thermal runaway phenomenon between adjacent battery cells 110.

[0041] The pad complex 120 includes a pair of swelling absorbent pads 121 and a heat insulating pad 122 interposed between the pair of swelling absorbent pads 121 .

[0042] When swelling occurs in the battery cells 110 due to repeated charging and discharging of the battery module and the battery cells 110 expand in a stacking direction, the swelling absorption pad 121 is compressed to absorb the swelling. In consideration of this function, the swelling absorption pad 121 is made of an elastic material, and may include at least one of expanded polypropylene (EPP) and urethane.

[0043] The swelling absorbing pad 121 is damaged and shrinks when the internal temperature of the battery module becomes high, about 100° C. to 300° C., due to abnormal heat generation in the battery module, and the thickness of the swelling absorbing pad 121 becomes almost zero if the high temperature state continues for a certain period of time.

[0044] The heat blocking pad 122 is interposed between a pair of swelling absorbing pads 121, and minimizes thermal transfer between the battery cells 110 located on both sides via the pad complex 120. In addition, the heat blocking pad 122 has a characteristic of expanding when the internal temperature of the battery module rises abnormally and exceeds a temperature (about 100°C to 300°C) at which the swelling absorbing pad 121 is damaged and contracts.

[0045] For such temperature-dependent operating characteristics, the heat shield pad 122 may include at least one of an epoxy resin, a butyl resin, and a polyvinyl chloride resin.

[0046] When the internal temperature of the battery module rises due to abnormal heat generation of the battery module and exceeds a reference temperature (about 100°C to 300°C), the heat blocking pad 122 expands to fill a space formed due to damage to the swelling absorption pad 121. That is, the heat blocking pad 122 prevents the swelling absorption pad 121 from being damaged due to abnormal heat generation of the battery module, causing a space to be generated between adjacent battery cells 110, thereby preventing the distance between the adjacent battery cells 110 from becoming closer, thereby efficiently blocking heat transfer.

[0047] The thermal insulation pad 122 has an expansion rate of about 5 to 40, and the expansion occurs only in the thickness direction. Therefore, when the internal temperature of the battery module becomes equal to or higher than a reference temperature, the thermal insulation pad 122 can expand sufficiently to prevent an empty space from being generated between adjacent battery cells 110.

[0048] In addition, the heat shield pad 122 has very low thermal conductivity in the range of about 0.05 to 0.5 W / mk, so that the heat transfer between the battery cells 110 located on both sides of the pad complex 120 can be minimized.

[0049] Hereinafter, a battery module according to another embodiment of the present invention will be described with reference to FIG.

[0050] FIG. 5 is a diagram showing a cell stack applied to a battery module according to another embodiment of the present invention.

[0051] The battery module according to another embodiment of the present invention differs from the battery module according to the above-mentioned embodiment of the present invention in that the number of pad complexes 120 applied is different, and other details are substantially the same as the above-mentioned embodiment.

[0052] Therefore, in the battery module according to another embodiment of the present invention, only the application positions of the plurality of pad complexes 120 will be described, and detailed descriptions of matters that overlap with the above-described embodiment will be omitted.

[0053] 5, a battery module according to another embodiment of the present invention includes a plurality of pad complexes 120. The pad complexes 120 are disposed between each of the cell groups including a plurality of battery cells 110. The number of battery cells 110 included in one cell group may be determined in consideration of the number of battery cells 110 included in the battery module, the capacity of the battery cells 110, the thickness of the pad complexes 120, and the like.

[0054] Hereinafter, a battery module according to still another embodiment of the present invention will be described with reference to FIG.

[0055] FIG. 6 is a diagram showing a cell stack applied to a battery module according to still another embodiment of the present invention.

[0056] The battery module according to yet another embodiment of the present invention differs from the battery module according to the above-mentioned embodiment of the present invention in that a swelling absorption pad 121 is further applied in addition to the pad complex 120, but otherwise is substantially identical.

[0057] Therefore, in the battery module according to the further embodiment of the present invention, only the application position of the additionally applied swelling absorbing pad 121 will be described, and detailed description of matters overlapping with the above-described embodiment will be omitted.

[0058] A battery module according to yet another embodiment of the present invention further includes, in addition to the pad complex 120 arranged at the center of the thickness direction of the cell stack 100, a plurality of swelling absorption pads 121 arranged between each of cell groups including a plurality of battery cells 110.

[0059] In this manner, when the swelling absorption pads 121 are applied to a plurality of locations of the cell stack 100, it is possible to stably absorb volume expansion due to swelling of the battery cells 110. In addition, since the battery module according to still another embodiment of the present invention includes the pad complex 120 at the center of the cell stack 100, like the battery module according to the above-described embodiment of the present invention, even if an abnormal heat generation phenomenon occurs, the propagation of the thermal runaway phenomenon can be prevented or delayed with the center of the cell stack 100 in the thickness direction as a boundary, thereby ensuring the safety of the use of the battery module.

[0060] As described above, the present invention has been described using limited embodiments and drawings. However, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention belongs within the technical spirit of the present invention and the equivalent scope of the claims.

[0061] Furthermore, the present invention preferably includes the following examples. [1] A cell stack including a plurality of battery cells and at least one pad composite interposed between adjacent battery cells; A module case that houses the cell stack, The pad complex comprises: A pair of swelling absorbing pads that are compressed by volume expansion due to swelling of the battery cell; a heat insulating pad interposed between the pair of swelling absorbing pads to block heat transfer between adjacent battery cells and expands at a preset reference temperature or higher. [2] The battery module according to [1], wherein the swelling absorption pad shrinks and reduces in thickness at a temperature equal to or higher than the reference temperature. [3] The battery module described in [2], wherein the heat insulating pad expands at a temperature equal to or higher than the reference temperature to fill a space created by the contraction of the swelling absorption pad. [4] The battery module according to [3], wherein the thermal insulation pad has a thickness-wise expansion coefficient of 5 to 40 at a temperature equal to or higher than the reference temperature. [5] The battery module described in any one of [1] to [4], wherein the battery cells are pouch-type battery cells. [6] A battery module described in any one of [1] to [5], wherein one pad complex is provided, and one pad complex is positioned at the center in the stacking direction of the cell stack. [7] The battery module described in [6], further including a plurality of swelling absorption pads arranged between each of cell groups including a plurality of battery cells. [8] A battery module described in any one of [1] to [5], wherein a plurality of the pad complexes are provided, and the plurality of pad complexes are arranged between cell groups each including a plurality of battery cells. [9] The battery module according to any one of [1] to [8], wherein the swelling absorption pad contains at least one of foamed polypropylene and urethane.

[10] The battery module according to any one of [1] to [9], wherein the heat insulating pad contains at least one of an epoxy-based resin, a butyl-based resin, and a polyvinyl chloride-based resin.

[11] A battery pack including a battery module according to any one of [1] to

[10] .

[12] A motor vehicle comprising a battery module according to any one of [1] to

[10] . [Explanation of symbols]

[0062] 100 Cell stack 110 Battery Cell 111 Pouch case, cell case 111a Storage unit 111b Sealing part 112 Electrode Lead 113 Sealing Tape 120 Pad Complex 121 Swelling Absorbent Pad 122 Heat Insulation Pad 200 module case

Claims

1. A pair of battery cells; a composite member including a pair of first members interposed between the pair of battery cells, and a second member interposed between the pair of first members in a state of contact with the pair of first members and having a thermal expansion coefficient different from that of the first members, The pair of first members shrink and reduce in thickness at a reference temperature or higher, The second member is configured to block heat transfer between the pair of first members without being damaged at a temperature equal to or higher than the reference temperature.

2. The battery module according to claim 1 , wherein the pair of first members includes an elastic material.

3. The battery module according to claim 1 , wherein the pair of first members are configured to absorb swelling of the battery cells.

4. The battery module of claim 1 , wherein the pair of first members are configured to be damaged and contract when an internal temperature of the battery module rises to a temperature of 100° C. to 300° C.

5. The battery module according to claim 1 , wherein the second member is configured to expand at or above the reference temperature to fill a space created by contraction of the pair of first members.

6. The battery module according to claim 5 , wherein the second member is configured to expand under a temperature condition in which the pair of first members are damaged and contract.

7. The battery module according to claim 6, wherein the second member is configured to expand when an internal temperature of the battery module increases to a temperature of 100°C to 300°C.

8. 2 . The battery module of claim 1 , wherein the pair of first members are configured to maintain contact with both sides of the second member regardless of an internal temperature of the battery module.

9. A battery pack comprising the battery module according to any one of claims 1 to 8.

10. A motor vehicle comprising a battery module according to any one of claims 1 to 8.

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