Secondary battery and method for manufacturing secondary battery

Abstract

The present invention relates to a secondary battery and a method for manufacturing the secondary battery and, more specifically, to a secondary battery and a method for manufacturing the secondary battery, wherein a liquefied gas electrolyte obtained by liquefying a gaseous electrolyte at high pressure is utilized to improve impregnation with an active material compared to existing electrolyte solutions so that a high-output battery can be designed and created, low-temperature performance can be achieved more easily compared to typical electrolyte solutions, and can be achieved more simply and efficiently.

Description

Secondary batteries and secondary battery manufacturing methods

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0118454, filed September 6, 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 method for manufacturing a secondary battery, and more particularly, to a secondary battery and a method for manufacturing a secondary battery, which utilize a liquefied gas electrolyte obtained by liquefying a gaseous electrolyte under high pressure, thereby enabling the design and implementation of a high-power battery by improving impregnation with an active material compared to a conventional electrolyte, and which enables the easier securing of low-temperature performance compared to a general electrolyte, and which enables the implementation of this more simply and efficiently compared to a conventional battery.

[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] In conventional cylindrical secondary batteries, a liquid electrolyte is inserted into the battery case along with the electrode assembly. An electrolyte is a substance that chemically dissociates into cations and anions in water or a polar solvent, resulting in a conductive solution. Typically, this electrolyte is injected into the can case in a liquid state. However, the degree to which this liquid electrolyte can penetrate the electrodes is limited, hindering the implementation of high-power batteries. Furthermore, secondary batteries generate internal heat during manufacturing and use, requiring low-temperature performance to dissipate this heat. Conventional liquid electrolytes also face limitations in this low-temperature performance. Consequently, the use of liquefied gas electrolytes, in which gaseous electrolytes are liquefied under high pressure, has emerged as an issue. However, these liquefied gas electrolytes are difficult to handle and utilize under normal room temperature and pressure conditions, necessitating research into simpler and more efficient solutions.

[0010] The present invention has been devised to solve the above problems, and the object of the present invention is to provide a secondary battery and a method for manufacturing a secondary battery, which can design and implement a high-power battery by improving the impregnation property with active materials compared to existing electrolytes by utilizing a liquefied gas electrolyte obtained by liquefying a gaseous electrolyte at high pressure, and can more easily secure low-temperature performance compared to general electrolytes, and can implement this more simply and efficiently compared to the prior art.

[0011] A secondary battery according to the present invention comprises an electrode assembly including a positive electrode, a separator, and a negative electrode, a case in which the electrode assembly is accommodated, and a liquefied gas electrolyte accommodated together with the electrode assembly inside the case, wherein the case comprises a side wall portion positioned on the side of the electrode assembly, and a catch portion extending inwardly from an upper end of the side wall portion at a predetermined angle with the side wall portion, a body in which an upper opening is formed inward of the catch portion and a lower opening is formed under the side wall portion, a top cap unit coupled to the upper opening of the body, and a bottom unit coupled to the lower opening of the body, wherein the top cap unit is pressed outward by the internal pressure of the case formed by the liquefied gas electrolyte, so that the top cap unit is caught on the catch portion and hermetically coupled to the upper opening.

[0012] The bottom unit can be welded to the lower opening of the body.

[0013] The top cap unit may include a protrusion inserted into an upper opening of the body, and a rim extension extending from the periphery of the protrusion toward the side wall and engaging a catch.

[0014] The border extension may extend from the lower perimeter of the protrusion toward the side wall.

[0015]

[0016] *As the top cap unit is pressed outward by the internal pressure of the case formed by the liquefied gas electrolyte, the rim extension can be pressed against the catch.

[0017] The positive tab connected to the positive electrode can be electrically connected to the top cap unit, and the negative tab connected to the negative electrode can be electrically connected to the bottom unit.

[0018] The method for manufacturing a secondary battery according to the present invention relates to a method for manufacturing the secondary battery described above, and includes an electrode tab connecting step of electrically connecting a positive electrode tab connected to a positive electrode of an electrode assembly to a top cap unit and electrically connecting a negative electrode tab connected to a negative electrode of the electrode assembly to a bottom unit, an electrode assembly receiving step of connecting the top cap unit to an upper opening of a body and accommodating the electrode assembly in an internal space of the body, a bottom unit connecting step of connecting the bottom unit to a lower opening of the body, an electrolyte injection step of injecting a liquefied gas electrolyte into the internal space of the body, and a sealing connecting step of hermetically connecting the top cap unit to an engaging portion by being pressed outward by the internal pressure of a case formed by the liquefied gas electrolyte, thereby causing the top cap unit to be caught in an engaging portion and sealedly connected to the upper opening.

[0019] The top cap unit includes a protrusion inserted into an upper opening of the body, and a rim extension that extends from the periphery of the protrusion toward the side wall and is caught by a catch, and the electrolyte injection step may be to inject a liquefied gas electrolyte into the internal space of the body through a space (G1) between the rim extension and the catch, while keeping a gap between the rim extension and the catch.

[0020] The sealing step may be a process in which the top cap unit is pressed outward by the internal pressure of the case formed by the liquefied gas electrolyte, thereby causing the edge extension to come into close contact with the engaging portion, thereby sealing the top cap unit to the upper opening.

[0021] Another type of secondary battery according to the present invention may further include a venting unit coupled to the top cap unit and configured to discharge internal gas of the case to the outside of the case when the internal temperature of the case becomes higher than a critical temperature.

[0022] The venting unit may include a base portion arranged on a surface of the edge extension portion facing the catch portion, and a variable portion installed on the base portion to face the catch portion and having a shape that changes when the temperature is above a critical temperature.

[0023] The variable portion may include a metal layer joint formed by bonding a first metal layer laminated on a base portion, and a second metal layer laminated on the first metal layer so as to face the catch portion and having a different thermal expansion coefficient from the first metal layer.

[0024] The metal layer joint is fixed on the base part at one end, the other end changes shape at a temperature above a critical temperature and presses the engaging part, and the force with which the other end of the metal layer joint presses the engaging part at a temperature above the critical temperature may be greater than the force (F) with which the top cap unit is pressed outward by the internal pressure of the case formed by the liquefied gas electrolyte.

[0025] When the other side of the metal layer joint presses the engaging portion, the edge extension portion is separated from the engaging portion to form a separation space (G2), and the gas inside the case can be discharged to the outside of the case through the separation space.

[0026] The base portion is formed in a circular shape with a through hole formed inside, and the protrusion of the top cap unit can be inserted into the through hole.

[0027] The variable portion is formed in a shape corresponding to the base portion, and four metal layer joints can be arranged at 90-degree intervals on the base portion.

[0028] The present invention relates to a secondary battery and a method for manufacturing a secondary battery, and the present invention relates to a secondary battery and a method for manufacturing a secondary battery, and by utilizing a liquefied gas electrolyte obtained by liquefying a gaseous electrolyte under high pressure, a high-power battery can be designed and implemented by improving impregnation with an active material compared to a conventional electrolyte, and low-temperature performance can be more easily secured compared to a general electrolyte, and furthermore, this can be implemented more simply and efficiently compared to a conventional electrolyte.

[0029] Figure 1 is a cross-sectional view illustrating a secondary battery according to Example 1 of the present invention.

[0030] Figure 2 is an exploded view showing the secondary battery of Figure 1 in disassembly.

[0031] Figure 3 is a diagram illustrating a method for manufacturing a secondary battery according to Example 2 of the present invention.

[0032] Figure 4 is a cross-sectional view showing an electrode tab connection step in a secondary battery manufacturing method according to Example 2 of the present invention.

[0033] FIG. 5 is a cross-sectional view showing an electrode assembly receiving step and a bottom unit bonding step in a secondary battery manufacturing method according to Example 2 of the present invention.

[0034] Figure 6 is a cross-sectional view showing an electrolyte injection step in a secondary battery manufacturing method according to Example 2 of the present invention.

[0035] Figure 7 is a cross-sectional view showing a hermetic bonding step in a secondary battery manufacturing method according to Example 2 of the present invention.

[0036] Figure 8 is a cross-sectional view showing a secondary battery according to Example 3 of the present invention.

[0037] FIG. 9 is a drawing showing a venting unit in a secondary battery according to Example 3 of the present invention, and is a drawing showing a state in which the shape has not changed.

[0038] Fig. 10 is a drawing showing a state in which the venting unit illustrated in Fig. 9 changes shape above a critical temperature.

[0039] FIG. 11 is a cross-sectional view illustrating a secondary battery according to Example 3 of the present invention, showing a state in which gas inside the secondary battery is discharged outside the case at a critical temperature or higher.

[0040] 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.

[0041] 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.

[0042] 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.

[0043]

[0044] Example 1

[0045] Fig. 1 is a cross-sectional view illustrating a secondary battery according to Example 1 of the present invention. Fig. 2 is an exploded view illustrating the secondary battery of Fig. 1 in an exploded form.

[0046] Hereinafter, a secondary battery (100) according to Example 1 of the present invention will be described with reference to FIGS. 1 and 2.

[0047] A secondary battery (100) according to Example 1 of the present invention includes an electrode assembly (110), a case (120), and a liquefied gas electrolyte (130).

[0048] The electrode assembly (110) may be formed by alternately arranging a positive electrode, a separator, and a negative electrode. The electrode assembly (110) may be a jelly roll-type electrode assembly (110) having a wound shape in which electrodes and separators are alternately arranged. This electrode assembly (110) may be an electrode roll in which one or more positive electrodes, one or more negative electrodes, and one or more separators are wound around each other.

[0049] The case (120) may be configured to accommodate the electrode assembly (110). The case (120) has an internal space formed therein, and the electrode assembly (110) may be vertically inserted into the internal space. Vertically inserted may mean that the electrode assembly (110) is inserted such that the winding axis of the electrode assembly (110) is perpendicular to the bottom surface of the case (120).

[0050] The electrolyte may be accommodated within the case (120) together with the electrode assembly (110). In the present invention, a liquefied gas electrolyte (130) different from a conventional liquid electrolyte may be used with this electrolyte configuration. The liquefied gas electrolyte (130) may refer to an electrolyte in a state where a gaseous electrolyte is liquefied under high pressure.

[0051] Referring to FIG. 2, the case (120) may include a body (121), a top cap unit (122), and a bottom unit (123).

[0052] First, the body (121) may include a side wall portion (121-1) and a catch portion (121-2). The side wall portion (121-1) may be configured to be located on the side of the electrode assembly (110). The catch portion (121-2) may be configured to extend inward from the upper end of the side wall portion (121-1) at a predetermined angle with the side wall portion (121-1). In FIG. 1, the side wall portion (121-1) and the catch portion (121-2) are illustrated to form a 90-degree angle. The catch portion (121-2) may be bent or folded from the side wall portion (121-1). It may be manufactured through various methods such as pressing, casting, forging, rolling, and injection molding. The case (120) may be made of a can material.

[0053] An upper opening (121-3) may be formed on the inside of the catch (121-2). This upper opening (121-3) may be processed by a punch. That is, it may be a hole made by a punch. In addition, a lower opening (121-4) may be formed on the lower side of the side wall (121-1). As will be described later, an electrode assembly (110) may be inserted into this lower opening (121-4).

[0054] Referring to FIGS. 1 and 2, the top cap unit (122) may be configured to be coupled to the upper opening (121-3) of the body (121). The top cap unit (122) may include a protrusion (122a) and a rim extension (122b). The protrusion (122a) may be a portion inserted into the upper opening (121-3) of the body (121). The rim extension (122b) may be a portion extending from the periphery of the protrusion (122a) toward the side wall (121-1) and caught by the catch (121-2). The rim extension (122b) may be configured to extend from the lower periphery of the protrusion (122a) toward the side wall (121-1). Through this form, the edge extension (122b) can be effectively caught on the catch (121-2) of the body (121) and can be supported by the catch (121-2). This can prevent the top cap unit (122) from being separated from the body (121).

[0055] The bottom unit (123) may be configured to be coupled to the lower opening (121-4) of the body (121). The bottom unit (123) may be coupled to the lower opening (121-4) of the body (121) by welding. When coupled by welding in this manner, the bottom unit (123) may seal the lower portion of the body (121). Accordingly, the electrolyte or internal gas may not be able to escape from the lower portion of the body (121).

[0056] Referring to FIG. 1, in the secondary battery (100) according to Embodiment 1 of the present invention, the top cap unit (122) can be pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte (130) (see arrow F in FIG. 1). When the top cap unit (122) is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte (130), the edge extension portion (122b) can be brought into close contact with the catch portion (121-2). In this manner, the top cap unit (122) can be caught by the catch portion (121-2) and hermetically connected to the upper opening (121-3). In addition, sealing of the battery can be achieved through this.

[0057] The secondary battery (100) according to Example 1 of the present invention, manufactured in this manner, utilizes a liquefied gas electrolyte (130) obtained by liquefying a gaseous electrolyte under high pressure, thereby improving the impregnation property with active materials compared to existing electrolytes, thereby enabling the design and implementation of a high-output secondary battery. In addition, by using a liquefied gas electrolyte (130), low-temperature performance can be more easily secured compared to general electrolytes.

[0058] In the secondary battery (100) according to the first embodiment of the present invention described above, if the top cap unit (122) is lowered further than in the state illustrated in FIG. 1, and thus the catch portion (121-2) of the body (121) and the edge extension portion (122b) of the top cap unit (122) are spaced apart from each other, a separation space (see G1 of FIG. 6) may be formed between the catch portion (121-2) of the body (121) and the edge extension portion (122b) of the top cap unit (122). And, internal gas and electrolyte, etc. may be discharged through this separation space. That is, the internal gas or vaporized electrolyte may pass through the gap between the catch (121-2) of the body (121) and the edge extension (122b) of the top cap unit (122) and may pass through the upper opening (121-3) of the body (121) and be discharged outside the case (120).

[0059] However, since the internal pressure of the case (120) formed by the liquefied gas electrolyte (130) strongly presses (F) the top cap unit (122) upward, the edge extension portion (122b) is pressed against the catch portion (121-2), and accordingly, no space can be formed between the edge extension portion (122b) and the catch portion (121-2). As a result, a secondary battery using a liquefied gas electrolyte (130) can be implemented more simply and efficiently than before.

[0060] In the secondary battery (100) according to Example 1 of the present invention, a positive electrode tab (140) connected to the positive electrode of the electrode assembly (110) can be electrically connected to a top cap unit (122). In addition, a negative electrode tab (150) connected to the negative electrode of the electrode assembly (110) can be electrically connected to a bottom unit (123). Through this, the upper end of the protrusion (122a) of the upper top cap unit (122) can function as a positive electrode terminal. In addition, the lower surface of the bottom unit (123) can function as a negative electrode terminal.

[0061]

[0062] Example 2

[0063] FIG. 3 is a diagram illustrating a method for manufacturing a secondary battery according to Embodiment 2 of the present invention. FIG. 4 is a cross-sectional view illustrating an electrode tab connection step in a method for manufacturing a secondary battery according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view illustrating an electrode assembly receiving step and a bottom unit bonding step in a method for manufacturing a secondary battery according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view illustrating an electrolyte injection step in a method for manufacturing a secondary battery according to Embodiment 2 of the present invention. FIG. 7 is a cross-sectional view illustrating a sealing bonding step in a method for manufacturing a secondary battery according to Embodiment 2 of the present invention.

[0064] Example 2 of the present invention differs from Example 1 in that it relates to a manufacturing method for manufacturing a secondary battery according to Example 1 of the present invention.

[0065] 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.

[0066] Referring to FIG. 3, the secondary battery manufacturing method according to Example 2 of the present invention may include an electrode tab connection step (S1), an electrode assembly receiving step (S2), a bottom unit bonding step (S3), an electrolyte injection step (S4), and a sealing bonding step (S5).

[0067] First, referring to FIG. 4, the electrode tab connection step (S1) may be a step of connecting a positive electrode tab (140) and a negative electrode tab (150) to an electrode assembly (110) formed by winding a positive electrode, a separator, and a negative electrode. Specifically, the positive electrode tab (140) connected to the positive electrode of the electrode assembly (110) may be electrically connected to the lower surface of the top cap unit (122). This connection may be a connection by welding (see W1). In addition, the negative electrode tab (150) connected to the negative electrode of the electrode assembly (110) may be electrically connected to the upper surface of the bottom unit (123). This connection may also be a connection by welding (see W2). Through this connection, in a secondary battery completed later, the upper portion of the protrusion (122a) of the top cap unit (122) may become a positive electrode terminal, and the lower portion of the bottom unit (123) may become a negative electrode terminal.

[0068] Referring to FIG. 5, the electrode assembly receiving step (S2) may be a step of receiving the electrode assembly (110), top cap unit (122), and bottom unit (123) assembly manufactured through the electrode tab connecting step (S1) into the body (121) of the secondary battery case (120). That is, while moving the electrode assembly (110), top cap unit (122), and bottom unit (123) assembly, which is positioned at the lower side of the body (121) upward, the electrode assembly (110), top cap unit (122), and bottom unit (123) assembly can be inserted into the body (121) through the lower opening (121-4). At this time, the top cap unit (122) can be coupled to the upper opening (121-3) of the body (121) and the electrode assembly (110) can be accommodated in the internal space of the body (121). That is, the protrusion (122a) of the top cap unit (122) can be inserted into the upper opening (121-3) of the body (121) and the combination of the electrode assembly (110), the top cap unit (122), and the bottom unit (123) can be accommodated within the body (121).

[0069] The bottom unit joining step (S3) may be a step of joining the bottom unit (123) to the lower opening (121-4) of the body (121) after the electrode assembly (110), the top cap unit (122), and the bottom unit (123) assembly are inserted and accommodated into the body (121). The method of joining the bottom unit (123) to the lower opening (121-4) of the body (121) may be a joining by welding (W3). When joined by welding in this way, the bottom unit (123) can seal the lower part of the body (121). Accordingly, the electrolyte or internal gas can be prevented from escaping through the lower part of the body (121).

[0070] Referring to Fig. 6, the electrolyte injection step (S4) may be a step of injecting a liquefied gas electrolyte (130) into the internal space of the body (121). The liquefied gas electrolyte (130) may be an electrolyte obtained by liquefying a gaseous electrolyte under high pressure.

[0071] The top cap unit (122) includes a protrusion (122a) and a rim extension (122b) as described above, and in the electrolyte injection step (S4), the liquefied gas electrolyte (130) can be injected into the internal space of the body (121) through the space (G1) between the rim extension (122b) and the catching portion (121-2) while the rim extension (122b) and the catching portion (121-2) are spaced apart from each other. That is, as illustrated in FIG. 6, when the top cap unit (122) is slightly pressed downward, a space (G1) can be formed between the rim extension (122b) and the catching portion (121-2). In this state, the liquefied gas electrolyte (130) can be injected into the body (121) of the case (120) while passing through the space between the protrusion (122a) and the upper opening (121-3) of the body (121) and the gap space (G1) between the catch (121-2) and the edge extension (122b) (see Q of FIG. 6). The liquefied gas electrolyte (130) is injected in a liquid state when injected into the body (121), but after entering the body (121), some of it can quickly vaporize due to the pressure difference, and through such an action, the internal pressure of the body (121) can be increased.

[0072] Referring to FIG. 7, the sealing bonding step (S5) may be a step in which, after the electrolyte injection step (S4), the top cap unit (122) is pressed outward (see arrow F in FIG. 7) by the internal pressure of the case (120) formed by the liquefied gas electrolyte (130), so that the top cap unit (122) is caught on the catch (121-2) and sealedly bonded to the upper opening (121-3).

[0073] Specifically, in the sealing bonding step (S5), as the top cap unit (122) is pressed outward (F) by the internal pressure of the case (120) formed by the liquefied gas electrolyte (130), the edge extension (122b) can be pressed against the catch (121-2). When pressed in this way, the internal electrolyte and other internal gases cannot be discharged to the outside of the case (120), and accordingly, the top cap unit (122) can be sealedly bonded to the upper opening (121-3) of the body (121).

[0074] The secondary battery (100) according to the previously described Example 1 can be manufactured by the secondary battery manufacturing method according to the second embodiment of the present invention described above. Therefore, the secondary battery manufacturing method according to the second embodiment of the present invention can design and implement a high-output battery with improved impregnation properties with active materials compared to existing electrolytes by utilizing a liquefied gas electrolyte obtained by liquefying a gaseous electrolyte under high pressure.

[0075] And, through the secondary battery (100) implemented by the secondary battery manufacturing method according to Example 2 of the present invention, low-temperature performance can be more easily secured compared to general electrolytes. In addition, the secondary battery manufacturing method according to Example 2 of the present invention can implement such an advanced secondary battery more simply and efficiently than the conventional method.

[0076]

[0077] Example 3

[0078] Fig. 8 is a cross-sectional view illustrating a secondary battery according to Embodiment 3 of the present invention. Fig. 9 is a cross-sectional view illustrating a venting unit (260) in a secondary battery according to Embodiment 3 of the present invention, showing a state in which the shape thereof is unchanged. Fig. 10 is a cross-sectional view illustrating a state in which the venting unit (260) illustrated in Fig. 9 is changed in shape above a critical temperature. Fig. 11 is a cross-sectional view illustrating a secondary battery according to Embodiment 3 of the present invention, showing a state in which gas inside the secondary battery is discharged to the outside of the case above a critical temperature.

[0079] Embodiment 3 of the present invention differs from Embodiments 1 and 2 in that it further includes a venting unit (260) compared to the secondary battery and secondary battery manufacturing method according to Embodiments 1 and 2 of the present invention.

[0080] Common contents with Examples 1 and 2 will be omitted as much as possible and Example 3 will be described. That is, it is self-evident that if contents not described in Example 3 are required, they can be considered as contents of Examples 1 and 2.

[0081] Referring to FIG. 8, the secondary battery (200) according to the third embodiment of the present invention may further include a venting unit (260) for discharging internal gas in the form of the secondary battery according to the first embodiment. The venting unit (260) may be coupled to the top cap unit (122) and configured to discharging internal gas of the case (120) to the outside of the case (120) when the internal temperature of the case (120) becomes higher than a critical temperature.

[0082] Referring to FIGS. 8 to 10, the venting unit (260) may include a base portion (261) and a variable portion (262). The base portion (261) may be a portion that is positioned on a surface of the edge extension portion (122b) facing the catch portion (121-2). The variable portion (262) may be installed on the base portion (261) so as to face the catch portion (121-2). The venting unit (260) may have a shape like a type of washer before the shape of the variable portion (262) changes.

[0083] The variable portion (262) may be a portion whose shape changes when the temperature is above the critical temperature. When the variable portion (262) changes shape when the temperature is above the critical temperature, the seal between the edge extension portion (122b) of the top cap unit (122) and the engaging portion (121-2) of the body (121) may be released. Accordingly, internal gas generated within the body (121) may be discharged to the outside of the battery case (120). This may prevent ignition or explosion of the secondary battery, which may occur due to internal gas pressure generated at high temperatures.

[0084] The base portion (261) may be formed in a circular shape with a through hole (261-1) formed therein. The base portion (261) may have a shape corresponding to the edge extension portion (122b) of the top cap unit (122). In addition, the base portion (261) may be arranged to overlap the edge extension portion (122b). For this purpose, the protrusion portion (122a) of the top cap unit (122) may be formed to be inserted into the through hole (261-1) of the base portion (261).

[0085] Fig. 9(a) is a drawing showing a plan view of a venting unit (260), and Fig. 9(b) is a drawing showing a front view of the venting unit (260) shown in Fig. 9(a). Both Fig. 9(a) and Fig. 9(b) show a state in which the shape of the variable portion (262) in the venting unit (260) does not change.

[0086] Fig. 10(a) is a drawing showing a plan view of a venting unit (260), and Fig. 10(b) is a drawing showing a front view of the venting unit (260) shown in Fig. 10(a). Fig. 10 shows a state in which the shape of the variable portion (262) has changed.

[0087] Referring to FIGS. 9 and 10, the variable portion (262) may be configured to change shape when the temperature increases based on the bimetallic principle formed by bonding two metals with different thermal expansion rates. Specifically, the variable portion (262) may include a metal layer bond (263) formed by bonding a first metal layer (263-1) laminated on a base portion (261) and a second metal layer (263-2) laminated on the first metal layer (263-1) so as to face the catch portion (121-2).

[0088] Here, the second metal layer (263-2) may be formed of a metal having a different thermal expansion coefficient from that of the first metal layer (263-1). For example, the thermal expansion coefficient of the second metal layer (263-2) may be greater than that of the first metal layer (263-1). Accordingly, the metal layer joint (263) may be bent in the direction of the first metal layer (263-1).

[0089] The variable portion (262) can be formed in a shape corresponding to the base portion (261). The metal layer joint (263) of the variable portion (262) can be viewed as a type of bimetal placed on the base portion (261). Four metal layer joints (263) can be arranged at 90-degree intervals on the base portion (261). One side portion (263a) of the metal layer joint (263) is fixed on the base portion (261), and the other side portion (263b) changes shape when the temperature is above a critical temperature and can press the catch portion (121-2). One side portion (263a) of the metal layer joint (263) fixed on the base portion (261) can be fixed on the base portion (261) by a fixing member (264). This fixing member (264) can be a bolt or a rivet.

[0090] Fig. 11 illustrates a state in which the shape of the variable portion changes and internal gas is vented when the venting unit (260) is mounted on the secondary battery (200) according to the third embodiment of the present invention. Referring to Figs. 10 and 11, the force with which the other side portion (263b) of the metal layer bonding body (263) presses the catch portion (121-2) above the critical temperature may be greater than the force (F) with which the top cap unit (122) is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte (130). Accordingly, when the other side portion (263b) of the metal layer bonding body (263) presses the catch portion (121-2), the edge extension portion (122b) may be spaced downward from the catch portion (121-2) to form a space (G2). And, through the separation space formed in this way, the internal gas of the case (120) can be discharged to the outside of the case (120).

[0091] Through this, it is possible to more simply and efficiently implement high-power secondary batteries with high impregnation with active materials and secondary batteries that can more easily secure low-temperature performance, and to use them more safely.

[0092]

[0093] 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.

[0094] [Explanation of symbols]

[0095] 100, 200: Secondary battery

[0096] 110: Electrode assembly (110)

[0097] 120: Case (120)

[0098] 121: Body (121)

[0099] 121-1: Side wall (121-1)

[0100] 121-2: Hook

[0101] 121-3: Upper opening

[0102] 121-4: Lower opening

[0103] 122: Top cap unit

[0104] 122a: Protrusion

[0105] 122b: Border extension

[0106] 123: Bottom Unit

[0107] 130: Liquefied gas electrolyte

[0108] 140: Positive tab

[0109] 150: Negative tab

[0110] 260: Venting Unit

[0111] 261: Bass section

[0112] 261-1: Through hole

[0113] 262: Variable part

[0114] 263: Metal layer joint

[0115] 263-1: First metal layer

[0116] 263-2: Second metal layer

[0117] 263a: One side

[0118] 263b: Other side

[0119] 264: Fixed member

[0120] S1: Electrode tab connection step

[0121] S2: Electrode assembly (110) acceptance stage

[0122] S3: Bottom unit combination stage

[0123] S4: Electrolyte injection stage

[0124] S5: Sealing stage

Claims

1. An electrode assembly including an anode, a separator, and a cathode; A case (120) in which the electrode assembly is accommodated; and A liquefied gas electrolyte is contained together with the electrode assembly inside the case (120); The above case (120) is A body (121) including a side wall portion (121-1) located on the side of the electrode assembly, and a catch portion extending inward at a predetermined angle from the upper end of the side wall portion (121-1), wherein an upper opening is formed on the inside of the catch portion, and a lower opening is formed on the lower side of the side wall portion (121-1); A top cap unit coupled to the upper opening of the above body (121); and It includes a bottom unit coupled to the lower opening of the above body (121), A secondary battery characterized in that the top cap unit is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte, and the top cap unit is caught on the catch and sealedly connected to the upper opening.

2. In claim 1, A secondary battery characterized in that the bottom unit is welded to the lower opening of the body (121).

3. In claim 1, The above top cap unit, A protrusion inserted into the upper opening of the body (121); and A secondary battery characterized by including a border extension portion that extends from the circumference of the protrusion toward the side wall portion (121-1) and is a portion that is caught by the catch portion.

4. In claim 3, A secondary battery characterized in that the above-mentioned edge extension extends from the lower periphery of the above-mentioned protrusion toward the side wall portion (121-1).

5. In claim 3, As the top cap unit is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte, A secondary battery characterized in that the above-mentioned edge extension is in close contact with the above-mentioned catch.

6. In claim 1, The positive tab connected to the positive electrode is electrically connected to the top cap unit, A secondary battery characterized in that the negative tab connected to the negative electrode is electrically connected to the bottom unit.

7. In a secondary battery manufacturing method for manufacturing a secondary battery according to claim 1, An electrode tab connection step of electrically connecting the positive electrode tab connected to the positive electrode of the electrode assembly (110) to the top cap unit and electrically connecting the negative electrode tab connected to the negative electrode of the electrode assembly (110) to the bottom unit; An electrode assembly (110) receiving step of coupling the top cap unit to the upper opening of the body (121) and receiving the electrode assembly (110) in the internal space of the body (121); A bottom unit joining step of joining the bottom unit to the lower opening of the body (121); An electrolyte injection step of injecting a liquefied gas electrolyte into the internal space of the body (121); A secondary battery manufacturing method including a sealing joining step in which the top cap unit is caught on the catch and sealedly joined to the upper opening as the top cap unit is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte.

8. In claim 7, The above top cap unit, It includes a protrusion inserted into the upper opening of the body (121), and a border extension extending from the circumference of the protrusion toward the side wall portion (121-1) and being a portion that is caught on the hook, The above electrolyte injection step is, A secondary battery manufacturing method characterized in that the liquefied gas electrolyte is injected into the internal space of the body (121) through the space (G1) between the frame extension and the catch while the frame extension and the catch are spaced apart.

9. In claim 8, The above sealed bonding step is: A secondary battery manufacturing method characterized in that the top cap unit is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte, thereby causing the edge extension to come into close contact with the catch, thereby sealingly connecting the top cap unit to the upper opening.

10. In claim 3, A secondary battery characterized in that it further includes a venting unit that is combined with the top cap unit and discharges internal gas of the case (120) to the outside of the case (120) when the internal temperature of the case (120) becomes higher than a critical temperature.

11. In claim 10, The above venting unit is, A base portion disposed on a surface of the above-mentioned edge extension portion facing the catch portion; and A secondary battery characterized in that it is installed on the base portion so as to face the catch portion, and includes a variable portion whose shape changes at a temperature higher than the critical temperature.

12. In claim 11, The above variable part is, A secondary battery characterized by comprising a metal layer assembly formed by bonding a first metal layer laminated on the base portion, and a second metal layer laminated on the first metal layer so as to face the catch portion and having a different thermal expansion coefficient from the first metal layer.

13. In claim 12, The above metal layer joint is, One side is fixed on the base portion, The other side changes shape above the critical temperature and presses the catch, A secondary battery characterized in that the force with which the other side of the metal layer joint presses the catch at a temperature higher than the critical temperature is greater than the force (F) with which the top cap unit is pressed outward by the internal pressure of the case (120) formed by the liquefied gas electrolyte.

14. In claim 13, A secondary battery characterized in that when the other side of the metal layer joint presses the catch, the edge extension is separated from the catch to form a separation space (G2), and the internal gas of the case (120) is discharged to the outside of the case (120) through the separation space.

15. In claim 12, The above base portion is formed in a circular shape with a through hole formed inside, A secondary battery characterized in that the protrusion of the top cap unit is inserted into the through hole.

16. In claim 15, The above variable portion is formed in a shape corresponding to the base portion, A secondary battery characterized in that four of the above metal layer bonding members are arranged at 90-degree intervals on the base portion.

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