Angular secondary battery

Abstract

The disclosed invention relates to a prismatic secondary battery, in one example, including a case made of a metal material, at least one battery cell housed in the case, a cooling part arranged on at least one side of the case, and a fixing body that fixes the cooling part and has a vent hole formed therein to guide gas generated in the battery cell and passing through the cooling part to the outside of the case.

Description

Technical Field

[0001] The present invention relates to a rectangular secondary battery capable of suppressing a heat propagation phenomenon in which other surrounding secondary batteries continuously overheat when thermal runaway occurs.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0061752 filed on May 20, 2022, and all contents disclosed in the document of the Korean patent application are included as part of this specification.

Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged, and in recent years, many research and developments have been carried out due to the possibility of miniaturization and large capacity. With the increase in technology development and demand for mobile devices, and the emergence of electric vehicles and energy storage systems in line with the contemporary requirements of environmental protection, the demand for secondary batteries as an energy source has increased even more rapidly.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, rectangular batteries, and pouch-type batteries according to the shape of the battery case. The electrode assembly mounted inside the battery case in a secondary battery is a power generation element capable of charge and discharge, which consists of a laminated structure of electrodes and a separator.

[0005] Since secondary batteries are required to be used continuously for a long time, it is necessary to effectively control the heat generated during the charge and discharge process. If the cooling of the secondary battery is not smoothly performed, the temperature rise causes an increase in current, and a positive feedback chain reaction in which the increase in current causes another temperature rise occurs, eventually leading to a catastrophic state of thermal runaway.

[0006] In addition, when secondary batteries form a group in the form of modules or packs, a thermal propagation phenomenon occurs where other secondary batteries in the vicinity are continuously overheated due to thermal runaway occurring in any one of the secondary batteries. Furthermore, since there is a high risk of fire due to the combustible gas released from the overheated secondary battery and ignition sources such as heating electrodes, it is necessary to suppress such a fire risk.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a secondary battery that can effectively suppress and prevent the thermal propagation phenomenon caused by thermal runaway in the secondary battery.

[0009] However, the technical problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those of ordinary skill in the art from the description of the invention described below.

Means for Solving the Problems

[0010] The present invention relates to a prismatic secondary battery. In one example, it includes a case made of a metal material, at least one or more battery cells housed in the case, a cooling part arranged on at least one side of the case, and a fixing body in which a venting hole is formed to fix the cooling part and guide the gas generated in the battery cell and passing through the cooling part to the outside of the case.

[0011] The cooling part includes an absorbent material impregnated with a liquid vaporized by heat generated in the battery cell, and a heat conduction body in which an insertion hole into which the absorbent material is inserted is formed.

[0012] In one embodiment of the present invention, the absorbent material is a highly absorbent matrix, and the highly absorbent matrix may include a superabsorbent polymer (SAP) or a superabsorbent fiber (SAF).

[0013] And the liquid impregnated in the absorbent material may be water.

[0014] And the cooling part may include a cover joined to the front and rear of the heat conduction body with respect to the flow direction of the gas generated in the battery cell and moving to the venting hole, and melted by the heat of the gas.

[0015] In one embodiment of the present invention, the battery cell is a pouch-type battery cell with electrode leads protruding to the outside, and the electrode leads may protrude toward one side of the case where the cooling part is disposed.

[0016] And the rectangular secondary battery of the present invention may include a side case coupled to an end portion on one side of the case and covering the fixed body, and a bus bar provided between the fixed body and the side case and electrically connected to the electrode lead.

[0017] A bus bar hole communicating with the venting hole and opening toward the outside of the side case is formed in the bus bar.

[0018] On the other hand, according to another embodiment of the present invention, the cooling part is disposed on at least one of the front and rear of the heat conduction body with respect to the flow direction of the gas generated in the battery cell and moving to the venting hole, and includes a filter that filters particles having a predetermined size or more contained in the gas.

[0019] Then, an end filter for filtering particles having a predetermined size or more contained in the gas that has passed through the cooling unit can be provided in the venting hole of the fixed body.

[0020] And the end filter can be broken when a pressure exceeding a predetermined value acts thereon, or can be separated from the venting hole.

Advantages of the Invention

[0021] According to the rectangular secondary battery of the present invention having the above-described configuration, the high-temperature gas and particles generated by the thermal runaway phenomenon are discharged to the outside through the cooling unit containing the cooling liquid. Therefore, in the rectangular secondary battery of the present invention, since the high-temperature ignition source released from the overheated battery cell is discharged after being cooled inside the case, the risk caused by the heat propagation phenomenon can be greatly reduced.

[0022] In addition, in the present invention, the rectangular secondary battery can effectively suppress the risk of an external fire caused by a high-temperature particle ignition source by installing a filter for filtering particles exceeding a certain size in the cooling unit and the venting hole.

[0023] However, the technical effects that can be obtained by the present invention are not limited to the above-described effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

Brief Description of the Drawings

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later. Therefore, the present invention should not be construed as being limited only to the matters described in such drawings.

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Embodiments for Carrying Out the Invention

[0025] Since the present invention can be subjected to various modifications and can have various embodiments, specific embodiments will be described in detail below.

[0026] However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention.

[0027] In the present invention, terms such as "including" and "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as precluding the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0028] 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 the case where it is directly "above" the other part but also the case 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 the case where it is directly "below" the other part but also the case where there is another part in between. Also, in this application, being "arranged on" can include not only the upper part but also the case of being arranged in the lower part.

[0029] The present invention relates to a rectangular secondary battery. In one example, the rectangular secondary battery of the present invention includes a case made of a metal material, at least one or more battery cells housed in the case, a cooling part arranged on at least one side of the case, and a fixing body in which a venting hole is formed to fix the cooling part and guide the gas generated by the battery cells and passing through the cooling part to the outside of the case.

[0030] Here, the cooling part includes an absorbent impregnated with a liquid that vaporizes due to the heat generated by the battery cells, and a heat conduction body in which an insertion hole for inserting the absorbent is formed.

[0031] In such a rectangular secondary battery of the present invention, high-temperature gas and particles generated by a thermal runaway phenomenon are discharged to the outside through a cooling part containing a cooling liquid. As a result, a high-temperature ignition source released from the overheated battery cells is cooled by the cooling part built into the case and then discharged, so that the risk caused by the heat propagation phenomenon can be greatly reduced.

[0032] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, the front-back, up-down, left-right directions specifying the relative positions used in the following description are for helping to understand the invention, and are based on the directions shown in the drawings unless otherwise defined.

[0033] (First Embodiment) FIG. 1 is a perspective view of a rectangular secondary battery 10 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the rectangular secondary battery 10 of FIG. 1.

[0034] As shown in the accompanying drawings, the rectangular secondary battery 10 of the present invention includes a case made of a metal material and at least one battery cell 200 housed in the case. As an example, the battery cell 200 in the illustrated embodiment is a pouch-type battery cell 200 with electrode leads 210 protruding from both sides in the width direction, and two pouch-type battery cells 200 are housed in the case.

[0035] The case can be made by extrusion molding a metal material such as aluminum, stainless steel, or an alloy containing the same. In the illustrated embodiment, considering easy accommodation of the battery cell 200 and the cost of extrusion molding, etc., the case includes a main case 110 having a cross-section in the shape of a lowercase English letter "n" and a lower plate 130 coupled to the lower open portion.

[0036] The rectangular secondary battery 10 of the present invention includes a cooling unit 300 disposed on at least one side of the case and a fixing body 400 for fixing the cooling unit 300 to the case.

[0037] The cooling unit 300 is for cooling the high-temperature gas generated by the battery cell 200 overheated due to a thermal runaway phenomenon to a temperature below the ignition temperature before discharging it to the outside. The cooling unit 300 operates in an emergency situation where high-temperature gas is generated due to thermal runaway, and it is necessary to maintain the cooling function properly in a normal state.

[0038] For this purpose, the cooling unit 300 includes an absorbent 310 impregnated with a liquid that vaporizes by the heat generated by the battery cell 200, and a heat conduction body 320 in which an insertion hole 322 for inserting the absorbent 310 is formed. The liquid impregnated in the absorbent 310 by the heat generated by the overheated battery cell 200, that is, the heat of the high-temperature gas, absorbs only the heat corresponding to the sensible heat and the latent heat, and the temperature of the high-temperature gas decreases in this process.

[0039] The heat conduction body 320 that houses the absorbent 310 inside the insertion hole 322 is a structure that supports the absorbent 310 and at the same time plays a role in dissipating the heat absorbed by the absorbent 310 to the surroundings. The more the heat conduction body 320 dissipates heat to the surroundings, the more the time until the liquid in the absorbent 310 vaporizes is delayed, and thereby the heat absorption effect of the liquid lasts longer.

[0040] The fixing body 400 serves to fix the cooling part 300 to the case and is provided with a venting hole 410 that guides the gas generated by the battery cell 200 and passing through the cooling part 300 to the outside of the case. The front and rear surfaces (based on the flow direction of the high-temperature gas) of the cooling part 300 fixed to the fixing body 400 are not blocked, and a clearance is formed between the rear surface of the cooling part 300 entering the inside of the fixing body 400 and the venting hole 410, so the gas flow is not obstructed.

[0041] In the first embodiment of the present invention, the absorbent 310 can be an absorbent 310 containing a superabsorbent matrix, for example, a superabsorbent polymer (SAP) or a superabsorbent fiber (SAF). The superabsorbent matrix can absorb a large amount of liquid by exhibiting capillary action in a porous or fibrous form, and the superabsorbent fiber can be manufactured by processing the superabsorbent polymer into a fibrous form such as a nonwoven fabric.

[0042] In the present invention, the specific types of superabsorbent polymers and superabsorbent fibers produced therefrom are not particularly limited, and any may be used without limitation as long as they have excellent absorption capacity for fluids, particularly water. In the present invention, examples of superabsorbent polymers include polyacrylic acid, polyacrylate, polyacrylate graft polymer, starch, crosslinked carboxymethylated cellulose, acrylic acid copolymer, hydrolyzed starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, saponified vinyl acetate-acrylic ester copolymer, hydrolyzed acrylonitrile copolymer, hydrolyzed acrylamide copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyvinylsulfonic acid, polyvinylphosphonic acid, polyvinylphosphoric acid, polyvinylsulfuric acid, sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl (meth)acrylamide, polyethyleneimine, polyallylamine, polyallylguanidine, polydimethyldiallylammonium hydroxide, quaternized polystyrene derivative, guanidine-modified polystyrene, quaternized poly(meth)acrylamide, polyvinylguanidine, and mixtures thereof. One or more selected from the group consisting of crosslinked polyacrylate, crosslinked polyacrylic acid, and crosslinked acrylic acid copolymer are preferably used, but the invention is not limited thereto.

[0043] In the present invention, the type of acrylic acid copolymer used as the superabsorbent polymer is not particularly limited, but is preferably a copolymer containing one or more comonomers selected from the group consisting of acrylic acid monomer and maleic acid, itaconic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-hydroxyethyl (meth)acrylate, and styrenesulfonic acid.

[0044] In the present invention, the superabsorbent polymer may have an absorption amount of 10 g / g to 500 g / g, preferably 50 g / g to 200 g / g with respect to water, but is not limited thereto. That is, 10 g to 500 g, preferably 50 g to 200 g of water can be absorbed per 1 g of the superabsorbent polymer.

[0045] In the present invention, the longer the absorption amount of the superabsorbent polymer with respect to water, the more the duration of the cooling effect can be improved. However, if it exceeds 500 g / g, the fluidity of the superabsorbent polymer increases and it is difficult to maintain its form, so effective cooling cannot be exerted. If it is less than 10 g / g, the duration of the cooling effect may be too short to be efficient.

[0046] Here, the liquid impregnated in the absorbent 310 may be water. Water corresponds to the substance having the largest sensible heat and latent heat among the liquids that can be easily obtained. Therefore, the water contained in the absorbent 310 is suitable for application to the cooling unit 300 of the present invention because the amount of heat absorbed during the phase change from the liquid state to the gas state is large.

[0047] And the cooling unit 300 may include a cover 330 joined to the front and rear of the heat conduction body 320 with respect to the flow direction of the gas generated in the battery cell 200 and moving to the venting hole 410 of the fixed body 400. The cover 330 is a film member for preventing the liquid impregnated in the absorbent 310 from being lost by natural evaporation, and melts by the heat of the gas flowing into the cooling unit 300, thereby exposing the absorbent 310 at a suitable time.

[0048] And it can be said that the electrode lead 210 of the battery cell 200 preferably protrudes toward one side of the case where the cooling unit 300 is disposed. Since the electrode lead 210 is a portion where current is concentrated and overheating is likely to occur, arranging the electrode lead 210 to face the cooling unit 300 has an advantage in that cooling and discharging of the high-temperature gas are immediately performed.

[0049] The rectangular secondary battery 10 of the present invention may include a side case 120 that is coupled to an end portion on one side of the case, that is, a side surface of the main case 110, and that covers the fixing body 400, and a bus bar 500 provided between the fixing body 400 and the side case 120. The bus bar 500 is a component that is electrically connected to the electrode lead 210, and a part of it is exposed to the outside through the cutout of the side case 120.

[0050] When the bus bar 500 is disposed within the side case 120, the bus bar 500 may block the bending hole 410 of the fixing body 400. In such a case, a bus bar hole 510 that communicates with the bending hole 410 and is open toward the outside of the side case 120 is formed in the bus bar 500.

[0051] (Second Embodiment) FIG. 5 is a drawing illustrating the cooling unit 300 in the second embodiment of the present invention, and FIG. 6 is a drawing illustrating a state in which an end filter 420 is provided in the bending hole 410 in the second embodiment of the present invention.

[0052] In the second embodiment of the present invention, by installing filter means inside the rectangular secondary battery 10, it is possible to prevent particles contained in the high-temperature gas from being directly discharged to the outside. Particles larger than a size that cannot be sufficiently cooled even when passing through the cooling unit 300 can become a high-temperature ignition source and induce an external fire. The second embodiment of the present invention reduces the risk of fire caused by such high-temperature particles. The second embodiment includes any one or more of two filter means.

[0053] First, the cooling unit 300 is disposed on at least one of the front and the rear of the heat conduction body 320 with respect to the flow direction of the gas that is generated in the battery cell 200 and moves to the bending hole 410, and includes a filter 340 that filters particles having a predetermined size or more contained in the gas.

[0054] The filter 340 is installed in front of and / or behind the heat conduction body 320, and filters the particles in the gas flowing into and out of the cooling unit 300. For reference, the filter 340 may be integrally laminated with a membrane member for preventing the liquid impregnated in the absorbent 310 from being lost. The membrane member, like the cover 330 described above, can be melted and removed by the heat of the gas.

[0055] Next, an end filter 420 that filters particles having a size equal to or larger than a predetermined size contained in the gas that has passed through the cooling unit 300 can be provided in the venting hole 410 of the fixed body 400. If the cooling unit 300 is provided with the filter 340, the end filter 420 of the venting hole 410 serves to filter the particles secondarily. The sizes of the particles filtered by the filter 340 of the cooling unit 300 and the end filter 420 of the venting hole 410 can be designed to be different from each other so as to optimize the mutually conflicting relationship between the filtering effect and the pressure increase. For example, the filter 340 of the cooling unit 300 having a relatively large area can be configured to filter particles of a relatively small size.

[0056] FIG. 7 is a side perspective view showing a venting hole 410 provided with a cooling unit 300 and an end filter 420. The embodiment of FIG. 7 shows a state in which both the filter 340 of the cooling unit 300 and the end filter 420 of the venting hole 410 are provided. For reference, FIG. 7 shows that a heat absorption pouch 600 is interposed between two pouch-type battery cells 200. The heat absorption pouch 600 incorporates a heat absorption material identical or similar to the heat absorption material 310 provided in the cooling unit 300 inside the pouch, and directly contacts the battery cell 200 to cause a heat absorption effect. The heat absorption pouch 600 can be provided with a fragile portion having locally low strength (such as bonding strength and tensile strength). The liquid in the heat absorption material absorbs heat and vaporizes, and the internal pressure increased by the gas causes the fragile portion to break and high-pressure gas to be ejected, thereby causing a strong cooling and / or fire extinguishing effect.

[0057] Also, for the safety of the rectangular secondary battery 10, when a pressure exceeding a predetermined value acts on the end filter 420, it can be designed to break or the end filter 420 can be separated from the venting hole 410. When the end filter 420 with a relatively narrow filtering area becomes clogged, the pressure inside the case rises above the limit, and the structure of the rectangular secondary battery 10 can collapse.

[0058] As a safety measure for such a case, the strength and structure can be designed so that the end filter 420 itself breaks when excessive pressure acts, or the end filter 420 can be made to detach from the venting hole 410. FIG. 8 is a drawing exemplarily showing a structure in which the end filter 420 can be separated by excessive internal pressure. A notch is formed in a protrusion 422 for fixing the end filter 420, and when a pressure above a certain level acts, the protrusion 422 breaks, and the end filter 420 is discharged to the outside.

[0059] The present invention has been described in more detail with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modifications that can replace these at the time of this application.

Explanation of Reference Numerals

[0060] 10: Square secondary battery 100: Case 110: Main case 120: Side case 130: Lower plate 200: Battery cell (pouch-type battery cell) 210: Electrode lead 300: Cooling part 310: Absorbent 320: Heat conduction body 322: Insertion hole 330: Cover 340: Filter 400: Fixing body 410: Venting hole 420: End filter 422: Protrusion 500: Bus bar 510: Bus bar hole 600: Heat absorption pouch

Claims

1. A case made of a metallic material, at least one or more battery cells housed within the case, a cooling part disposed on at least one side of the case, a fixing body having a venting hole formed therein for fixing the cooling part and guiding gas generated by the battery cells and passing through the cooling part to the outside of the case, comprising: high-temperature gas and particles generated by a thermal runaway phenomenon are cooled through the cooling part and discharged to the outside, and heat absorbed by the cooling part is dissipated to the surroundings, a rectangular secondary battery.

2. A case made of a metallic material, at least one or more battery cells housed within the case, a cooling part disposed on at least one side of the case, a fixing body having a venting hole formed therein for fixing the cooling part and guiding gas generated by the battery cells and passing through the cooling part to the outside of the case, comprising: the cooling part an absorbent impregnated with a liquid that vaporizes due to heat generated by the battery cells, a heat conduction body having an insertion hole into which the absorbent is inserted, a rectangular secondary battery.

3. The absorbent is a highly absorbent matrix, the rectangular secondary battery according to Claim 2.

4. The highly absorbent matrix includes a highly absorbent polymer or highly absorbent fiber, the rectangular secondary battery according to Claim 3.

5. The liquid is water, the rectangular secondary battery according to Claim 4.

6. The cooling part is joined to the front and rear of the heat conduction body with respect to the flow direction of gas generated by the battery cells and moving to the venting hole, and includes a cover that melts due to the heat of the gas, the rectangular secondary battery according to any one of Claims 2 to 5.

7. The battery cell is a pouch-type battery cell with electrode leads protruding to the outside, the rectangular secondary battery according to Claim 1.

8. The electrode lead protrudes toward the one side of the case where the cooling part is disposed, the rectangular secondary battery according to Claim 7.

9. A case made of a metallic material, at least one or more battery cells housed within the case, a cooling part disposed on at least one side of the case, a fixing body having a venting hole formed therein for fixing the cooling part and guiding gas generated by the battery cells and passing through the cooling part to the outside of the case, comprising: the battery cell A pouch-type battery cell with electrode leads protruding externally, The electrode leads are, Protruding toward the one side of the case where the cooling part is arranged, A side case that is coupled to the end portion on the one side of the case and covers the fixed body, A bus bar provided between the fixed body and the side case and electrically connected to the electrode leads, A rectangular secondary battery including.

10. The rectangular secondary battery according to claim 9, wherein a bus bar hole that communicates with the venting hole and opens toward the outside of the side case is formed in the bus bar.

11. The cooling part is, Arranged on at least one of the front and the rear of the heat conduction body with respect to the flow direction of the gas generated in the battery cell and moving to the venting hole, and includes a filter that filters particles of a predetermined size or more contained in the gas. The rectangular secondary battery according to claim 2.

12. In the venting hole of the fixed body, The rectangular secondary battery according to claim 11, further comprising an end filter that filters particles of a predetermined size or more contained in the gas that has passed through the cooling part.

13. The end filter is, The rectangular secondary battery according to claim 12, which breaks when a pressure exceeding a predetermined value acts or is separated from the venting hole.

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