Secondary battery and battery module including same

Abstract

The present invention relates to a secondary battery and a battery module including same and, more specifically, to a secondary battery and a battery module including same, wherein internal explosive power of the secondary battery can be minimized by rapidly discharging internal heat and internal gas pressure by performing venting for internal gas discharge according to a normal design value at room temperature and implementing, under a high temperature condition, faster venting than the prior art.

Description

Secondary battery and battery module including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0113892, filed August 29, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a secondary battery and a battery module including the same, and relates to a secondary battery and a battery module including the same, which can minimize the internal explosive power of a secondary battery by quickly discharging internal heat and internal gas pressure by venting for internal gas discharge according to a typical design value at room temperature and implementing faster venting than before at high temperature conditions.

[0005] Secondary batteries are classified into cylindrical and prismatic batteries, in which the electrode assembly is built into a cylindrical or prismatic metal can, and pouch-type batteries, in which the electrode assembly is built into a pouch-type case made of aluminum laminate sheet, depending on the shape of the battery case.

[0006] In addition, the electrode assembly built into the battery case is a power plant capable of charging and discharging, which is composed of a stacked structure of anode / separator / cathode, and can be classified into a jelly roll-type structure in which a separator is interposed between long sheet-shaped cathodes coated with active materials and wound, a stack-type structure in which a plurality of cathodes of a predetermined size are sequentially stacked with a separator interposed between them, and a stack / folding type electrode assembly in which bicells or full cells in which a predetermined number of cathodes and anodes are stacked with a separator interposed between them are wound.

[0007] Among them, jelly-roll type electrode assemblies are widely manufactured because they are easy to manufacture and have the advantages of high energy density per weight. The jelly-roll type electrode assembly can be manufactured by assembling a laminate having a long sheet-shaped positive electrode and negative electrode with a separator interposed therebetween, and winding the laminate in the longitudinal direction of the sheet while contacting a core at one end of the electrode laminate. In addition, such a jelly-roll type electrode assembly can be inserted into a battery case made of a cylindrical metal can to form a cylindrical secondary battery.

[0008] These cylindrical secondary batteries are designed with high energy density, and this increased energy density requires a high level of stability in lithium secondary batteries, and accordingly, the demand for cylindrical batteries is also increasing.

[0009] Figure 1 is a cross-sectional view showing a cap assembly in a conventional secondary battery.

[0010] Referring to Fig. 1, a conventional secondary battery (1) includes an electrode assembly (not shown), a can (not shown) for accommodating the electrode assembly, and a cap assembly (2) for covering an upper opening of the can. Fig. 1 specifically illustrates the cap assembly (2). The electrode assembly and the can are omitted for convenience of explanation. In Fig. 1, the cap assembly (2) may include a top cap (11), a safety vent (12), and a current interrupt device (13). The top cap (11) may be configured to form an outermost terminal for electrical connection with the outside. The safety vent (12) may be located on the lower side of the top cap (11) and may be connected to the top cap (11) at an outer portion. At this outer portion, the safety vent (12) may be seated on a main gasket (14). The safety vent (12) may be configured such that the central region (15), which is the inner region of the outer portion, changes shape when the internal pressure of the can increases. In particular, the central region (15) may move upward, and the shape of the safety vent may be reversed accordingly.

[0011] And the current cutoff device (13) may be located at the lower side of the safety vent (12), and may be configured to have an electrode tab connected to the electrode assembly on the lower side, and may be connected to the safety vent (12) in the central area (15) of the safety vent (12). An auxiliary gasket (16) may be located at the outer part of the current cutoff device to prevent contact between the safety vent (12) and the current cutoff device (13) except for the central area (15).

[0012] Conventionally, the central region (15) of the safety vent (12) and the central region of the current cutoff device (13) were welded together. A notch (13-a) may be formed around the central region (15) which is the welded joint. The notch (13-a) may be a portion that breaks when the internal pressure of the can rises above a critical point. When the notch (13-a) breaks, the central portion inside the notch (13-a) and the outer portion of the notch (13-a) break apart from each other, thereby cutting off the current.

[0013] Specifically, before the notch (13-a) is broken, a current path is formed from the electrode of the electrode assembly to the electrode tab connected to the electrode, from the electrode tab to the current cutoff device (13) connected to the electrode tab, from the current cutoff device (13) to the safety vent (12) welded, and from the outer part of the safety vent (12) to the top cap (11) connected to the safety vent (12). However, when the notch (13-a) is broken due to an increase in the internal pressure of the can, the current can no longer flow from the current cutoff device (13) to the safety vent (12), and thus the current can be cut off.

[0014] When the internal pressure of the can rises above the critical point, the central part (15) of the safety vent (12) moves upward. At this time, the central part inside the notch (13-a) of the current cutoff device (13), which is the part welded to the central part of the safety vent (12), moves upward together with the safety vent (12), but the outer part of the notch (13-a) of the current cutoff device (13) does not rise but remains in place. Accordingly, the notch (13-a) part may be broken to cut off the current. For this current cutoff operation, the central part of the safety vent (12) and the central part of the current cutoff device (13) are connected to each other. And, conventionally, a welding connection was used for this connection.

[0015] Meanwhile, a venting notch (21) may be formed in the safety vent (12). After the safety vent (12) is deformed upward, if the internal pressure gradually increases, the venting notch (21) formed in the safety vent (12) may be broken. Accordingly, the internal gas may be discharged to the outside. That is, the internal gas may come out through the broken notch (13-a) of the current cutoff device (13) and then come out again through the broken venting notch (21) of the safety vent (12). Then, the gas may be finally discharged to the outside of the secondary battery (1) through a gas discharge hole (not shown) formed in the top cap.

[0016] However, the problem arose when secondary batteries exploded under high-temperature conditions due to thermal runaway, a phenomenon that caused them to explode with great force. Specifically, the magnitude of secondary battery explosions under high-temperature conditions was significantly greater than the magnitude of secondary battery explosions caused by internal gases at room temperature.

[0017] The present invention has been devised to solve the above problems, and the task of the present invention is to provide a secondary battery and a battery module including the same, which can minimize the internal explosive power of the secondary battery by quickly discharging internal heat and internal gas pressure by venting for internal gas discharge according to a typical design value at room temperature and by implementing faster venting than before at high temperature conditions.

[0018] A secondary battery according to the present invention includes an electrode assembly, a can in which the electrode assembly is accommodated, and a cap assembly covering an opening of the can, wherein the cap assembly includes a top cap forming an outermost terminal for electrical connection with the outside, a safety vent positioned on the lower side of the top cap and connected to the top cap at an outer portion, the shape or position of a predetermined area inside the outer portion changing when the internal pressure of the can rises above a threshold value, and a current interrupt device (CID) positioned on the lower side of the safety vent, having an electrode tab connected to the electrode assembly at a lower surface thereof, and a portion of an upper surface of which is joined to the safety vent at a predetermined area of ​​the safety vent, wherein the safety vent includes a venting notch having a recessed shape on an upper surface or a lower surface, and an additional material is attached to a surface of the venting notch, and the additional material has a higher thermal conductivity than the thermal conductivity of the safety vent.

[0019] A venting notch may be formed on the underside of the safety vent.

[0020] The venting notch may have a V-shape, and the additional material may include a first portion attached to a surface of the venting notch. The first portion may have a thickness thinner than the thickness of the safety vent.

[0021] The first portion may be coated on the venting notch surface to cover the entire venting notch surface.

[0022] The additional material may further include a second portion attached to an opposite side of the surface where the venting notch is formed in the safety vent, and the second portion may be attached at a position corresponding to the position where the venting notch is formed.

[0023] The safety vent may be made of aluminum, and the additional material may be made of either silver or copper.

[0024] The additive material may be attached by either soldering or dipping.

[0025] The safety vent comprises an aluminum material, and the additional material may comprise any one of silicon carbide (SiC), beryllium oxide (BeO), aluminum nitride (AlN), aluminum oxide (Al2O3), carbon, and a polymer material.

[0026] The additive material may be applied by either spraying or dipping.

[0027] The battery module according to the present invention may include a plurality of secondary batteries described above.

[0028] The secondary battery and battery module including the same according to the present invention can vent internal gas according to a typical design value at room temperature, and can achieve faster venting than before at high temperature conditions, thereby minimizing the internal explosive power of the secondary battery by quickly discharging internal heat generation and internal gas pressure.

[0029] Figure 1 is a cross-sectional view showing a cap assembly in a conventional secondary battery.

[0030] Figure 2 is a cross-sectional view illustrating a secondary battery according to Example 1 of the present invention.

[0031] Figure 3 is an enlarged cross-sectional view of area A of Figure 2.

[0032] Figure 4 is a cross-sectional view illustrating a secondary battery according to Example 2 of the present invention.

[0033] Figure 5 is an enlarged cross-sectional view of area A' of Figure 4.

[0034] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0035] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0036] 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.

[0037]

[0038] Example 1

[0039] Fig. 2 is a cross-sectional view illustrating a secondary battery according to Example 1 of the present invention. Fig. 3 is an enlarged cross-sectional view of area A of Fig. 2.

[0040] Hereinafter, a secondary battery (10) according to Example 1 of the present invention will be described with reference to FIGS. 2 and 3.

[0041] A secondary battery (10) according to Example 1 of the present invention includes an electrode assembly (not shown), a can (not shown), and a cap assembly (100).

[0042] The electrode assembly may be formed by alternately arranging anodes, separators, and cathodes. The electrode assembly may be a jelly-roll-type electrode assembly having a coiled shape in which electrodes and separators are alternately arranged. Such an electrode assembly may be an electrode roll in which one or more anodes, one or more cathodes, and one or more separators are coiled around each other.

[0043] The can may be configured to insert an electrode assembly. The can has an internal space formed therein, and the electrode assembly can be vertically inserted into the internal space. Vertically inserted may mean that the electrode assembly is inserted such that the winding axis of the electrode assembly is perpendicular to the bottom of the can. The can may have an opening at the top. That is, the can may be configured to have an open top and a bottom and sidewalls. The electrode assembly and the can may be electrode assemblies and cans typically used in cylindrical secondary batteries.

[0044] Referring to FIG. 2, the cap assembly (100) may be configured to cover the upper opening of the can. Specifically, the cap assembly (100) may be configured to include a top cap (110), a safety vent (120), and a current interrupt device (130) (Current Interrupt Device, CID).

[0045] The top cap (110) may be configured to form an outermost terminal for electrical connection with the outside. It may include a central portion having a convex shape upwardly spaced apart from a safety vent (120) described below by a predetermined distance, and an outer portion connected to the safety vent (120).

[0046] The safety vent (120) may be located on the lower side of the top cap (110) and connected to the top cap (110) at the outer portion. Furthermore, the safety vent (120) may be configured to change the shape or position of a predetermined region inside the outer portion when the internal pressure of the can rises above a threshold value. The predetermined region inside the outer portion may have the shape of a disk with the lowest height in the center. The safety vent may be connected to a current interrupting device (130) described below at the central portion (125).

[0047] The current interrupting device (130) may be located below the safety vent (120). An electrode tab (not shown) connected to the electrode assembly may be connected to the lower surface of the current interrupting device (130). In addition, the current interrupting device (130) may be configured to be connected to the safety vent (120) by welding or the like in the predetermined area of ​​the safety vent (120). In addition, the predetermined area may be, for example, the central portion (125).

[0048] In the secondary battery (10) according to Embodiment 1 of the present invention, the safety vent (120) may include a venting notch (121) having a recessed shape on the upper or lower surface. As illustrated in FIG. 2, as a specific example, the venting notch (121) may be formed on the lower surface of the safety vent (120). In addition, the venting notch (121) may have a V shape.

[0049] And referring to FIGS. 2 and 3, an additional material (160) is attached to the surface of the venting notch (121). The additional material (160) may be a material having a higher thermal conductivity than the thermal conductivity of the safety vent (120).

[0050] When configured this way, venting for internal gas discharge occurs at room temperature according to typical design values, and faster venting is achieved at high temperatures compared to conventional venting. Consequently, internal heat generation and internal gas pressure can be quickly discharged, minimizing the internal explosive potential of the secondary battery.

[0051] Specifically, the safety vent (120) can be typically formed of aluminum. At room temperature, it can maintain its existing mechanical properties regardless of thermal conductivity. Accordingly, the venting notch (121) can rupture at the originally designed venting pressure, allowing internal gas to escape.

[0052] However, when high temperature conditions are encountered, the additional material (160) with high thermal conductivity can quickly transfer high temperature heat to the venting notch (121). Accordingly, the venting notch (121) can be quickly and early broken under high temperature conditions, and the internal gas can be quickly discharged to the outside of the secondary battery (10).

[0053] This may be a method of differentiating the physical properties at room temperature and high temperature at the venting notch (121). Under high temperature conditions, the physical properties may be rapidly and locally reduced only at the venting notch (121), thereby advancing the venting point. This can prevent a large explosion that may occur in the secondary battery (10) at high temperatures.

[0054] Specifically, the additional material (160) may be attached to the surface of the V-shaped venting notch (121). The additional material (160) may be attached to the surface of the venting notch (121) so as to cover the entire surface of the V-shaped venting notch (121). In this case, more effective heat transfer and fracture of the venting notch (121) may be achieved under high temperature conditions.

[0055] And the additional material (160) may be provided with a thickness thinner than the thickness of the safety vent (120). For example, the additional material (160) may be thinly coated on the surface of the venting notch (121) so as to cover the entire surface of the venting notch (121).

[0056] The safety vent (120) may include an aluminum material, and the additional material (160) may include either silver or copper. Since silver and copper have higher thermal conductivity than aluminum, they can effectively transfer heat to the venting notch (121) under high temperature conditions, thereby causing a fracture.

[0057] When the additional material (160) is a metal material such as silver or copper, the additional material (160) can be attached or coated by either soldering or dipping.

[0058] Here, soldering may be a method of joining base materials without melting them using molten metal. In other words, it may be a method of coating by melting silver and copper, but coating an additional material (160) while ensuring that the venting notch (121) portion is not melted.

[0059] Dipping may be a method of coating the additional material (160) on the venting notch (121) by immersing the safety vent (120) in a solution of the additional material (160) while covering the portion other than the venting notch (121) with a mask and leaving the venting notch (121) exposed.

[0060] Meanwhile, the additional material (160) may be a non-metallic material. For example, the additional material (160) may include any one of silicon carbide (SiC), beryllium oxide (BeO), aluminum nitride (AlN), aluminum oxide (Al2O3), carbon, and a polymer material.

[0061] When the additional material (160) is a non-metal, the additional material (160) may be attached or coated by either spraying or dipping.

[0062] The spray method may be a method in which the portion other than the venting notch (121) is covered with a mask, the venting notch (121) is exposed, and the additional substance (160) solution is sprayed onto the safety vent (120) to coat the venting notch (121) with the additional substance (160). The dipping method may be the same method as described above.

[0063] Meanwhile, the battery module according to the present invention may include a plurality of secondary batteries (10) according to Example 1 described above.

[0064]

[0065] Example 2

[0066] Fig. 4 is a cross-sectional view illustrating a secondary battery according to Example 2 of the present invention. Fig. 5 is an enlarged cross-sectional view of area A' of Fig. 4.

[0067] Embodiment 2 of the present invention differs from Embodiment 1 in that, in the secondary battery according to Embodiment 1 of the present invention, additional materials are formed on both the upper and lower surfaces of the safety vent.

[0068] We will omit, as much as possible, the common content with Example 1 and describe Example 2. In other words, it is self-evident that if content not described in Example 2 is required, it can be considered as the content of Example 1.

[0069] Referring to FIGS. 4 and 5, the secondary battery according to Example 2 of the present invention may have the following specific form.

[0070] In the secondary battery (20) according to Example 2 of the present invention, the additional material (260) may include a first portion (261) and a second portion (262). The first portion (261) may be a portion attached to the surface of the venting notch (121). And the second portion (262) may be a portion attached to the opposite side of the surface where the venting notch (121) is formed in the safety vent (120).

[0071] When the venting notch (121) is formed on the lower surface of the safety vent (120), the first portion (261) may be an additional material (260) portion coated or attached to the surface portion of the venting notch (121) on the lower surface of the safety vent (120), and the second portion (262) may be an additional material portion coated or attached to a position corresponding to a position where the venting notch (121) is formed on the upper surface of the safety vent (120). Alternatively, the second portion (262) may be an additional material (260) portion attached to a position corresponding to a position where the first portion (261) is located on the safety vent (120). The first portion (261) and the second portion (262) may be at positions where at least a portion overlaps with each other in the vertical direction.

[0072] Here, the first part (261) and the second part (262) may have a thickness thinner than the thickness of the safety vent (120). And the first part (261) may be coated on the surface of the venting notch (121) so as to cover the entire surface of the venting notch (121).

[0073] When formed in this way, heat conduction occurs on both the upper and lower sides in high-temperature situations, so the venting notch (121) can be broken more quickly and effectively.

[0074] Accordingly, the secondary battery (20) according to Example 2 of the present invention having the above configuration performs venting for internal gas discharge according to typical design values ​​at room temperature, but can achieve faster and more effective venting than before under high-temperature conditions. This allows for rapid discharge of internal heat and internal gas pressure, thereby more effectively preventing a large explosion of the secondary battery.

[0075]

[0076] 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.

[0077] [Explanation of symbols]

[0078] 10, 20: Secondary batteries

[0079] 100: Cap assembly

[0080] 110: Top cap

[0081] 120: Safety vent

[0082] 121: Venting Notch

[0083] 130: Current Interrupter (CID)

[0084] 135: Blocking notch

[0085] 140: Main gasket

[0086] 150: Auxiliary gasket

[0087] 160, 260: Additional substances

[0088] 261: Part 1

[0089] 262: Part 2

Claims

1. Electrode assembly; A can in which the electrode assembly is stored; and Including a cap assembly covering the opening of the can, The above cap assembly, A top cap forming the outermost terminal for electrical connection to the outside; A safety vent located on the lower side of the top cap and connected to the top cap at the outer portion, wherein the shape or position of a predetermined area inside the outer portion changes when the internal pressure of the can rises above a threshold value; and A current interrupt device (CID) is located on the lower side of the safety vent, has an electrode tab connected to the electrode assembly on the lower side, and has a portion of the upper surface joined to the safety vent in the predetermined area of ​​the safety vent. The above safety vent includes a venting notch shaped like a recess on the upper or lower surface, An additional material is attached to the surface of the above venting notch, A secondary battery characterized in that the above-mentioned additional material has a thermal conductivity higher than the thermal conductivity of the above-mentioned safety vent.

2. In claim 1, A secondary battery characterized in that the above venting notch is formed on the lower surface of the safety vent.

3. In claim 1, The above venting notch has a V shape, The above additional substances are, A secondary battery characterized by including a first part attached to the above venting notch surface.

4. In claim 3, A secondary battery characterized in that the first part has a thickness thinner than the thickness of the safety vent.

5. In claim 4, A secondary battery characterized in that the first part is coated on the venting notch surface so as to cover the entire venting notch surface.

6. In claim 3, The above additional substances are, Further comprising a second part attached to the opposite side of the surface where the venting notch is formed in the safety vent; A secondary battery characterized in that the second part is attached at a position corresponding to the position where the venting notch is located.

7. In claim 1, The above safety vent comprises aluminum material, A secondary battery characterized in that the above-mentioned additional material comprises one of silver and copper materials.

8. In claim 7, A secondary battery characterized in that the above-mentioned additional material is attached by either soldering or dipping.

9. In claim 1, The above safety vent comprises aluminum material, A secondary battery characterized in that the above-mentioned additional material comprises any one of silicon carbide (SiC), beryllium oxide (BeO), aluminum nitride (AlN), aluminum oxide (Al2O3), carbon, and a polymer material.

10. In claim 9, A secondary battery characterized in that the above-mentioned additional material is attached by either spraying or dipping.

11. A battery module comprising a plurality of secondary batteries according to claim 1.

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