Secondary batteries

Abstract

The disclosed invention relates to a secondary battery, and in one example, includes a metal case and at least one battery cell housed inside the case, the case including cooling water stored in a hollow space formed between an inner surface facing the battery cell and an outer surface spaced apart from the inner surface.

Description

[Technical Field]

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

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0047720, filed April 18, 2022, and Korean Patent Application No. 10-2022-0185543, filed December 27, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference. [Background technology]

[0003] Unlike primary batteries, secondary batteries are rechargeable and have the potential to be small and have large capacities, which has led to extensive research and development in recent years. Demand for secondary batteries as an energy source is rapidly increasing due to the increasing technological development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in response to modern demands for environmental protection.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. The electrode assembly installed inside the battery case of a secondary battery is a power generating element that can be charged and discharged and is made up of a laminated structure of electrodes and a separator.

[0005] Since secondary batteries are required to be used continuously for long periods of time, it is necessary to effectively control the heat generated during the charging and discharging process.If secondary batteries are not cooled smoothly, a positive feedback chain reaction will occur in which a rise in temperature causes an increase in current, and the increase in current causes another rise in temperature, ultimately leading to a catastrophic state of thermal runaway.

[0006] In addition, when secondary batteries are grouped together in the form of a module or pack, thermal runaway in one secondary battery can cause thermal propagation, in which other surrounding secondary batteries are continuously overheated.Furthermore, there is a high risk of fire due to ignition sources such as flammable gases emitted from overheated secondary batteries and heating electrodes, so it is necessary to prevent this risk of fire. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent No. 10-1270796 Summary of the Invention [Problem 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 heat propagation phenomenon caused by thermal runaway that occurs in the secondary battery.

[0009] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0010] The present invention relates to a secondary battery, and in one example, includes a metal case and at least one battery cell housed inside the case, and the case contains coolant stored in a hollow space formed between an inner surface facing the battery cell and an outer surface spaced apart from the inner surface.

[0011] In one embodiment of the present invention, the hollow portion has an opening at each side of the case.

[0012] Side adapters may be attached to both side surfaces of the case to seal the entrance of the hollow portion from the outside.

[0013] Here, the side adapter has a groove that is coupled to the inner surface and the outer surface of the case, and the inlet and outlet of the hollow portion communicate with each other inside the groove.

[0014] Furthermore, the side adapter has a water inlet that exposes a portion of the entrance / exit of the hollow portion to allow water to be poured in from the outside, and the water inlet is sealed with a plug.

[0015] The plug is made of a material having a relatively low melting point compared to the case.

[0016] The water inlet may be located at the top of the case.

[0017] The secondary battery of the present invention may include a side cap that is coupled to the side adapter and forms an internal space in which the electrode leads of the battery cell are located, and a bus bar that is disposed inside the side cap and electrically connected to the electrode leads, and a portion of the bus bar exposed through a cutout provided in the side cap serves as an electrode terminal.

[0018] According to an embodiment of the present invention, the bus bar includes a vent hole formed on the electrode terminal, and when the plug is melted, cooling water and / or steam stored in the hollow portion of the case passes through the water inlet and is discharged from the vent hole.

[0019] In some embodiments, the venting hole may be equipped with a filter that filters out particles above a certain size.

[0020] Meanwhile, according to another embodiment of the present invention, the battery pack may further include a guide body disposed inside the side cap to face the bus bar, and the guide body guides a flow of gas generated in the battery cell and a flow of coolant and / or water vapor discharged through the water inlet to the vent hole.

[0021] The guide body may include a plurality of guide plates that divide the flow of gas generated in the battery cells and the flow of cooling water and / or water vapor discharged through the water inlet into a plurality of branches.

[0022] The guide body may be disposed in close contact with the inner surface of the side adapter and may have a through hole corresponding to the water inlet of the side adapter.

[0023] Furthermore, the vent hole can accommodate a filter that filters out particles above a certain size, and the guide body can have a storage space formed in the inlet area of ​​the filter.

[0024] The storage space can be disposed below the water inlet. [Effects of the Invention]

[0025] According to the secondary battery of the present invention having the above-described configuration, the coolant stored inside the case quickly absorbs and disperses heat in an environment where temperature rises frequently, such as during rapid charging, thereby suppressing the occurrence of thermal runaway and maintaining performance and lifespan without a high temperature rise.

[0026] Furthermore, when a thermal runaway phenomenon occurs in a secondary battery, the present invention not only suppresses heat propagation through the insulating properties of the coolant stored inside the case, but also significantly reduces the risk of fire by suppressing flames by cooling ignition sources such as flammable gases and heating electrodes emitted from overheated battery cells when the low-melting-point plug sealing the coolant melts and erupts into the coolant and / or steam.

[0027] In addition, the present invention can effectively reduce the risk of external fires caused by ignition sources of high-temperature particles by installing a filter that filters out particles above a certain size in the vent hole provided in the secondary battery.

[0028] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Brief explanation of the drawings]

[0029] 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 concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in such drawings. [Figure 1] 1 is a perspective view of a secondary battery according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the secondary battery of FIG. [Figure 3] 2 is a diagram illustrating a case of a secondary battery in detail; [Figure 4] 1 is a diagram illustrating a structure in which a side adapter is connected to a secondary battery case. [Figure 5] 10 is a diagram illustrating a state in which cooling water is poured into a case to which a side adapter is connected and sealed. [Figure 6] 10 is a diagram illustrating a state in which cooling water is poured into a case to which a side adapter is connected and sealed. [Figure 7] 10 is a diagram illustrating a state in which a side cap and a bus bar are coupled to a side of a case. [Figure 8] 10 is a diagram illustrating a state in which cooling water stored in a case is discharged from a vent hole together with high-temperature gas. [Figure 9] FIG. 4 is an exploded perspective view of a secondary battery according to a second embodiment of the present invention. [Figure 10]FIG. 4 is a front view illustrating the mounting structure of the guide body. [Figure 11] FIG. 10 is a cross-sectional view taken across the vent hole and the guide body. [Figure 12] 10 is a view illustrating a state in which cooling water stored in a case is guided and discharged to a vent hole together with high-temperature gas in a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Because the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0031] However, this is not intended to limit the invention to any particular embodiment, but should be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0032] In the present invention, the terms "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and should be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0033] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion therebetween. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion therebetween. Furthermore, in this application, being "located on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0034] The present invention relates to a secondary battery, and in one example, includes a metal case and at least one battery cell housed inside the case, the case containing coolant stored in a hollow space formed between an inner surface facing the battery cell and an outer surface spaced apart from the inner surface. That is, the present invention includes a configuration in which the case itself stores coolant.

[0035] According to the secondary battery of the present invention having the above-described configuration, the coolant stored inside the case quickly absorbs and disperses heat in an environment where temperature rises frequently, such as during rapid charging, thereby suppressing the occurrence of thermal runaway and maintaining performance and lifespan without a high temperature rise.

[0036] Furthermore, when a thermal runaway phenomenon occurs in a secondary battery, the present invention not only suppresses heat propagation through the insulating properties of the coolant stored inside the case, but also significantly reduces the risk of fire by suppressing flames by cooling ignition sources such as flammable gases and heating electrodes emitted from overheated battery cells when the low-melting-point plug sealing the coolant melts and erupts into the coolant and / or steam.

[0037] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, directions such as front-back, up-down, left-right, and right-left used to designate relative positions are intended to facilitate understanding of the invention, and unless otherwise specified, are based on directions shown in the drawings.

[0038] (First embodiment) FIG. 1 is a perspective view of a secondary battery 10 according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of the secondary battery 10 of FIG.

[0039] As shown in the accompanying drawings, a secondary battery 10 of the present invention includes a metal case 100 and at least one battery cell 200 housed in the case 100. As an example, in the illustrated embodiment, the battery cell 200 is a pouch-type battery cell 200 with bidirectional terminals, and two pouch-type battery cells 200 are housed in the case 100.

[0040] FIG. 3 is a detailed view of the case 100 of the secondary battery 10. The case 100 has a hollow portion 102 formed between an inner surface facing the battery cell 200 and an outer surface spaced apart from the inner surface, and coolant is stored in the hollow portion 102 formed within the thickness of the case 100.

[0041] The case 100 may be formed integrally with the hollow portion 102 by extruding a metal material such as aluminum, stainless steel, or an alloy containing these. In the illustrated embodiment, taking into consideration the ease of housing the battery cells 200 and the cost of extrusion molding, the case 100 comprises a main case 110 having a cross section shaped like a lowercase letter "n" and a lower plate 120 that is connected to the opening at the bottom.

[0042] The hollow portion 102 has openings 104 on both sides of the case 100. This is in consideration of the direction of continuous extrusion molding of the main case 110, and also to allow cooling water to be smoothly injected into the hollow portion 102.

[0043] Since the hollow portion 102 of the case 100 is open on both sides, a separate sealing structure is required to store the cooling water. In the present invention, to seal the cooling water, side adapters 300 are attached to both sides of the case 100 to seal the inlet / outlet 104 of the hollow portion 102 from the outside. Figure 4 shows the structure in which the side adapters 300 are attached to the case 100.

[0044] The side adapter 300 has grooves 310 that are coupled to the inner and outer surfaces of the case 100. The corners of the case 100 are inserted into the grooves 310 to form an interconnection, and a tight seal is formed by welding or the like. In addition, the inlets 104 of the hollow portion 102 disposed in the grooves 310 of the side adapter 300 communicate with each other within the grooves 310. That is, the bottom surface of the grooves 310 is spaced apart from the inlets 104 of the hollow portion 102 to form a space, so that the side adapter 300 seals the cooling water in the hollow portion 102 so that it does not leak out to the outside, while allowing mutual flow within the grooves 310.

[0045] Furthermore, the side adapter 300 has a water inlet 320 that exposes a portion of the entrance / exit 104 of the hollow portion 102 to allow water to be poured from the outside, and the water inlet 320 is sealed with a plug 330. Figures 5 and 6 are diagrams illustrating the state in which cooling water W has been poured into the case 100 to which the side adapter 300 is coupled and sealed. Figure 5 is a side cross-sectional view, and Figure 6 illustrates the state in which the water inlet 320 is blocked with the plug 330.

[0046] The water inlet 320 is formed to penetrate the bottom surface of the groove 310. Since the inlets 104 of the hollow portions 102 in the groove 310 are connected to each other, even if the cooling water W is poured into only a partially opened water inlet 320, the cooling water W is poured into all of the hollow portions 102. Once the pouring of the cooling water W is complete, the water inlet 320 is closed with a plug 330 to complete the sealing. Here, when considering air venting, etc., it may be advantageous to position the water inlet 320 at the top of the case 100 to pour the cooling water W smoothly.

[0047] The plug 330 is made of a material having a relatively low melting point compared to the case 100. The plug 330 may be made of various materials such as metal, non-metal, synthetic resin, rubber, etc. In addition, the plug 330 may be manufactured separately and attached to the water inlet 320, or the water inlet 320 may be closed by techniques such as brazing or soldering.

[0048] In the secondary battery 10 of the present invention, the coolant W stored in the case 100 quickly absorbs and dissipates heat in environments where temperature rises are common, such as rapid charging, thereby suppressing the occurrence of thermal runaway and contributing to maintaining performance and lifespan.

[0049] Furthermore, when a thermal runaway phenomenon occurs in the secondary battery 10, the present invention not only suppresses heat propagation to the surrounding area through the insulating properties of the cooling water W stored inside the case 100, but also significantly reduces the risk of fire by cooling flammable gases and ignition sources such as heating electrodes released from the overheated battery cells 200 when the low-melting-point plugs 330 sealing the cooling water W melt and spray into the cooling water and / or steam, thereby suppressing flames.

[0050] That is, the cooling water stored in the case 100 in the present invention exhibits a variety of functions, including heat insulation, heat absorption, heat dispersion, cooling, and fire extinguishing, thereby significantly improving the safety of the secondary battery 10.

[0051] The secondary battery 10 of the present invention may include a side cap 400 that is coupled to the side adapter 300 and forms an internal space in which the electrode leads 210 of the battery cells 200 are located, and a bus bar 500 that is disposed inside the side cap 400 and electrically connected to the electrode leads 210 of the battery cells 200. A portion of the bus bar 500 exposed through a cutout 410 formed in the side cap 400 may serve as an electrode terminal 510. Figure 7 illustrates the state in which the side cap and the bus bar are coupled to the side of the case.

[0052] The cutout 410 may be located generally above the center of the height of the secondary battery 10, i.e., at the top of the secondary battery 10. This is because it is a suitable location for discharging water vapor vaporized from the coolant W stored inside the case 100 to the outside of the secondary battery 10, while taking into consideration the convenience of electrical connection to the bus bar 500 exposed by the cutout 410.

[0053] Furthermore, according to an embodiment of the present invention, the bus bar 500 may include vent holes 520 formed on the electrode terminals 510. As a result, when the battery cells 200 overheat and the plugs 330 blocking the water inlet 320 melt, the cooling water and / or water vapor stored in the hollow portion 102 of the case 100 passes through the water inlet 320 to cool the high-temperature gas generated in the battery cells 200 and ignition sources such as the heating electrodes, and then is discharged from the vent holes 520.

[0054] 8 is a diagram illustrating the state in which the coolant W stored in the case 100 is discharged together with high-temperature gas (venting gas) from the vent hole 520. The plug 330 that had been closing the water inlet 320 located at the top of the case 100 melts and disappears due to the heat of the overheated battery cells 200, allowing water vapor to be discharged from the water inlet 320 and venting gas to be discharged from the overheated battery cells 200.

[0055] In the case of a pouch-type battery cell 200, the area where the sealing is relatively weak is the portion where the electrode lead 210 protrudes to the outside. Referring to FIG. 2, the electrode lead 210 is located relatively lower on the battery cell 200 than the water inlet 320. As a result, water vapor discharged from the top of the case 100 and venting gas discharged from the bottom of the battery cell 200 collide in between, causing mutual heat exchange, which lowers the temperature of the venting gas. The water vapor and venting gas, whose temperatures have been adjusted in this manner, are both discharged to the outside through the venting hole 520. In this way, the internal pressure of the case 100 is relieved by proper ventilation through the venting hole 520, thereby preventing the structure of the secondary battery 10 from colliding.

[0056] In addition, depending on the embodiment, a filter 530 that filters out particles above a certain size may be installed in the vent hole 520. The filter 530 may effectively reduce the risk of an external fire that may be caused by ignition sources of high-temperature particles generated in the overheated battery cell 200 leaking to the outside.

[0057] (Second embodiment) 9 is an exploded perspective view of a secondary battery 10 according to a second embodiment of the present invention, which further includes a guide body 600 disposed inside the side cap 400 to face the bus bar 500. The guide body 600 serves to guide the flow of gas generated in the battery cell 200 and the coolant and / or water vapor discharged through the water inlet 320 to the vent hole 520.

[0058] 10 is a front view illustrating the mounting structure of the guide body 600, and FIG. 10(b) illustrates a state in which the side cap 400 and the bus bar 500 therein illustrated in FIG. 10(a) have been removed. In the embodiment illustrated in the drawings, the guide body 600 includes multiple guide plates 610, which split the flow of gas generated in the battery cells 200 and the flow of coolant and / or water vapor discharged through the water inlet 320 into multiple branches, as illustrated in FIG. 12. Splitting the gas flow and the coolant flow into multiple branches allows for more uniform cooling and smoother flow. In addition, the contact area between the gas and the coolant is increased, improving overall cooling efficiency.

[0059] 11 is a cross-sectional view taken across the vent hole 520 and the guide body 600. The guide body 600 is disposed in close contact with the inner surface of the side adapter 300, so that the gas flow and the cooling water flow can flow into the guide body 600 immediately without being disturbed. Here, the guide body 600 has a through hole 620 corresponding to the water inlet 320 so that the guide body 600, which is in close contact with the inner surface of the side adapter 300, does not block the water inlet 320.

[0060] Meanwhile, when a filter 530 that filters out particles above a certain size is installed in the vent hole 520 of the bus bar 500, the guide body 600 may accordingly include a storage space 630 formed in the inlet region of the filter 530. The storage space 630 is a space where the gas and cooling water stay for a while just before being discharged, and serves to alleviate congestion during external discharge by allowing sufficient cooling to occur between the gas and cooling water once again before being discharged through the filter 530 and the vent hole 520.

[0061] Here, it can be said that it is preferable that the storage space 630 is disposed below the water inlet 320 so as not to obstruct the flow of cooling water and / or steam discharged from the water inlet 320.

[0062] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, so it should be understood that there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0063] 10: Secondary battery 100: Case 102:Hollow part 104: Entrance / exit 110: Main case 120: Lower plate 200: Battery cells 210: Electrode lead 300: Side adapter 310: Groove 320: Water inlet 330: Stopper 400: Side cap 410: Incision 500: Busbar 510: Electrode terminal 520: Venting hole 530: Filter 600: Guide body 610: Guide plate 620:Through hole 630: Storage space W: Cooling water

Claims

1. Metal case and At least one battery cell housed inside the case; A secondary battery comprising: the case includes cooling water stored in a hollow space formed between an inner surface of the case facing the battery cell and an outer surface of the case spaced apart from the inner surface, The hollow portion has an opening on each side surface of the case, a side adapter that seals the entrance of the hollow portion from the outside is coupled to both side surfaces of the case; the side adapter has grooves that are coupled to the inner and outer surfaces of the case; The inlets and outlets of the hollow portions communicate with each other inside the groove.

2. the side adapter has a water inlet that exposes a portion of the entrance / exit of the hollow portion to allow water to be poured in from the outside, The secondary battery according to claim 1 , wherein the water inlet is sealed by a plug.

3. The secondary battery according to claim 2 , wherein the plug is made of a material having a relatively lower melting point than the case.

4. The secondary battery according to claim 3 , wherein the water inlet is disposed at an upper portion of the case.

5. The secondary battery is a side cap coupled to the side adapter and defining an internal space in which electrode leads of the battery cell are positioned; a bus bar disposed inside the side cap, electrically connected to the electrode lead, and a portion of the bus bar exposed through a cutout formed in the side cap serving as an electrode terminal; The secondary battery according to claim 3 , comprising:

6. the bus bar has a vent hole formed in the electrode terminal, The secondary battery according to claim 5 , wherein when the plug is melted, the cooling water and / or water vapor stored in the hollow portion of the case passes through the water inlet and is discharged from the vent hole.

7. The secondary battery according to claim 6 , wherein the vent hole is provided with a filter for filtering out particles exceeding a certain size.

8. a guide body disposed inside the side cap so as to face the bus bar; The secondary battery according to claim 6 , wherein the guide body guides the flow of gas generated in the battery cell and the flow of cooling water and / or water vapor discharged through the water inlet to the vent hole.

9. The guide body is 9. The secondary battery according to claim 8, further comprising a plurality of guide plates that divide the flow of gas generated in the battery cells and the flow of cooling water and / or water vapor discharged through the water inlet into a plurality of branches.

10. The guide body is The secondary battery according to claim 8 , wherein the secondary battery is disposed in close contact with the inner surface of the side adapter and has a through-hole corresponding to a water inlet of the side adapter.

11. A filter that filters out particles above a certain size is installed in the vent hole, The secondary battery according to claim 8 , wherein the guide body includes a storage space formed in an inlet region of the filter.

12. The secondary battery according to claim 11 , wherein the storage space is disposed below the water inlet.

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