Secondary battery

Abstract

Disclosed is a secondary battery which prevents heat of a battery cell from being transferred to the periphery of the battery cell when an event occurs in the battery cell, the secondary battery comprising: an electrode assembly comprising a first electrode plate and a second electrode plate, each of the first electrode plate and the second electrode plate has an electrode uncoated portion protruding from at least one side of the electrode assembly; a case configured to receive the electrode assembly, the case having an opening formed in a lower end thereof; a cap assembly formed at one surface of the case, the cap assembly configured to seal the case, the cap assembly including an electrode terminal electrically connected to the uncoated portion of the electrode; and a sealing plate coupled along a periphery of an opening formed in a lower end of the housing.

Description

Technical Field

[0001] Embodiments relate to a secondary battery. Background Art

[0002] Unlike primary batteries, which cannot be charged, secondary batteries are batteries that can be charged and discharged. Low-capacity batteries having individual battery cells packaged in the form of a pack are used in small portable electronic devices such as cellular phones and video cameras, and large-capacity batteries including dozens of battery packs connected to each other are widely used as power sources for driving motors of hybrid vehicles.

[0003] Secondary batteries are manufactured in various shapes including cylindrical shapes and prismatic shapes. Secondary batteries are manufactured by receiving an electrode assembly including a positive electrode plate, a negative electrode plate, a separator between the positive electrode plate and the negative electrode plate as an insulator, and an electrolyte in a housing and coupling a cover plate to the housing. The electrode assembly is electrically connected to the electrode terminal via a current collecting unit. The internal volume of the housing varies depending on the structure of the current collecting unit. It is desirable to provide a secondary battery with a larger capacity within a given size. Summary of the invention

[0004] Technical issues

[0005] The embodiment provides a secondary battery which prevents heat of a battery cell from being transferred to surroundings of the battery cell when an event occurs in the battery cell.

[0006] Technical Solution

[0007] A secondary battery according to one embodiment includes: an electrode assembly including a first electrode plate and a second electrode plate, each of the first electrode plate and the second electrode plate having an electrode uncoated portion protruding from at least one side of the electrode assembly; a shell configured to receive the electrode assembly, the shell having an opening formed in a lower end of the shell; a cover assembly formed at one surface of the shell, the cover assembly being configured to seal the shell, the cover assembly including an electrode terminal electrically connected to the electrode uncoated portion; and a sealing plate coupled along a periphery of the opening formed in the lower end of the shell.

[0008] The sealing plate may be coupled along the periphery of the opening by welding.

[0009] The sealing plate can be welded along the periphery of the opening at a welding depth of 300um to 400um.

[0010] The bursting pressure of the sealing plate through the seal relative to the housing can be set to 7 bar to 10 bar.

[0011] The case may have a larger area than the electrode assembly, the case may be provided with an opening at a lower end of the case, and the case may be sealed by a sealing plate.

[0012] If the internal pressure of the housing reaches a predetermined rupture pressure, at least three sides of the sealing plate may be ruptured from the opening of the housing.

[0013] If the sealing plate is broken from the case, the electrode assembly may be separated from the cap assembly and may fall off from the case.

[0014] If the sealing plate is broken from the case, the electrode assembly may be separated from the cap assembly at a portion where the electrode assembly and the cap assembly are welded to each other.

[0015] The case may be provided with an opening at each of an upper portion and a lower portion of the case, the cover assembly may be coupled to the upper opening, and the sealing plate may be coupled to the lower opening.

[0016] The cap assembly may include a cap plate configured to seal an upper opening of the case and an electrode terminal extending through the cap plate to be electrically connected to the electrode assembly, and the sealing plate may be coupled to the cap plate at a position corresponding to the cap plate.

[0017] The cover plate may not be provided with a vent.

[0018] The case may be provided with openings at each of opposite sides and a lower portion of the case, a cover assembly may be coupled to each of the side openings, and a sealing plate may be coupled to the lower opening.

[0019] The cap assembly may include a pair of cap plates configured to seal a side opening of the case and an electrode terminal extending through each of the cap plates to be electrically connected to the electrode assembly, and the sealing plate may be coupled between the pair of cap plates to correspond to the pair of cap plates.

[0020] The electrode assembly may be located between the pair of cap plates, and the sealing plate may be positioned to correspond to a lower portion of the electrode assembly.

[0021] Both ends of the electrode assembly may be coupled to a pair of cap plates, respectively.

[0022] Beneficial Effects

[0023] In a secondary battery according to an embodiment, when an event occurs and the internal pressure of a battery cell reaches a predetermined rupture pressure, the sealing plate may rupture from the case so that the electrode assembly may be discharged from under the case, thereby quickly separating the electrode assembly from the surrounding battery cells to prevent heat spread. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view showing a secondary battery according to an embodiment;

[0025] Figure 2 is a rear perspective view showing a secondary battery according to an embodiment;

[0026] Figure 3a It is along Figure 1 A cross-sectional view taken along line AA';

[0027] Figure 3b yes Figure 3a An enlarged view of a portion P;

[0028] Figure 4 is an exploded perspective view showing a coupling relationship between an electrode assembly and a current collector;

[0029] Figure 5 shows a change in temperature over time when an event occurs in a secondary battery according to an embodiment;

[0030] Figure 6 is a perspective view showing a secondary battery according to another embodiment;

[0031] Figure 7a It is along Figure 6 A cross-sectional view taken along line BB';

[0032] Figure 7b yes Figure 7a An enlarged view of a portion P;

[0033] Figure 8 is a partial cross-sectional view showing a coupling relationship between an electrode assembly and an electrode terminal in a secondary battery according to another embodiment; and

[0034] Fig. 9 is a partial perspective view illustrating a coupling relationship between an electrode assembly and an insulating plate in a secondary battery according to another embodiment. DETAILED DESCRIPTION

[0035] Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings.

[0036] The embodiments are provided to more fully illustrate the present disclosure to those skilled in the art, and the following embodiments may be modified in various other forms, and the scope of the present disclosure is not limited to the following embodiments. The embodiments are provided to make the present disclosure more accurate and complete, and to fully convey the ideas of the present disclosure to those skilled in the art.

[0037] In the following drawings, for ease of description and clarity, the thickness or size of each layer is exaggerated, and the same reference numerals in the drawings indicate the same elements. As used herein, the term "and / or" includes any one of the listed items and any combination of one or more thereof.

[0038] For ease of description, spatially related terms such as "under", "below", "down", "above", and "on" may be used herein to describe the relationship of one element or feature to other elements or features as shown in the accompanying drawings. These spatial terms are intended to facilitate understanding of the present disclosure according to various manufacturing processes or use states of the secondary battery, and are not intended to limit the present disclosure. For example, if the secondary battery in the accompanying drawings is flipped, the element described as "under" or "below" becomes "on" or "above". Therefore, "under" includes "above" or "below".

[0039] Figure 1 is a perspective view showing a secondary battery according to an embodiment. Figure 2 is a rear perspective view showing a secondary battery according to an embodiment. Figure 3a It is along Figure 1 A cross-sectional view taken along line AA'. Figure 3b yes Figure 3a An enlarged view of part P. Figure 4 is an exploded perspective view showing a coupling relationship between an electrode assembly and a current collector. Figure 5 FIG. 1 shows a change in temperature over time when an event occurs in a secondary battery according to an embodiment.

[0040] See also Figure 1 3 , a secondary battery 100 according to an embodiment may include an electrode assembly 110 , current collecting units 120 , 130 , an auxiliary tab 140 , a case 150 , a cap assembly 160 , and a sealing plate 180 .

[0041] The electrode assembly 110 may be formed by stacking a plurality of laminates, each of which includes a first electrode plate, a separator, and a second electrode plate, each of which may be formed as a thin plate or a film. The first electrode plate may operate as a positive electrode, and the second electrode plate may operate as a negative electrode. The first electrode plate and the second electrode plate may be provided with different polarities relative to each other by the selection of those skilled in the art.

[0042] The first electrode plate may be formed by applying a first electrode active material such as a transition metal oxide to a first electrode current collector made of a metal foil such as aluminum, and may include a first electrode uncoated portion 111 as a region where the first electrode active material is not applied. The first electrode uncoated portion 111 may provide a path for current flow between the first electrode plate and the outside.

[0043] The first electrode uncoated portion 111 may be formed to overlap at the same position when the first electrode plates are stacked, thereby forming a multi-tab structure. The first electrode uncoated portion 111 may be formed so as to protrude from one side of the electrode assembly 110, and a plurality of first electrode uncoated portions may be welded to each other to form a single first current collecting tab. The first current collecting tab 111 may be integrally formed with the first electrode plate and may be withdrawn from each of the stacked first electrode plates, thereby improving the efficiency of current collection from the electrode assembly 100. The first current collecting tab 111 may be made of a member separated from the first electrode plate by the selection of a person skilled in the art.

[0044] The second electrode plate may be formed by applying a second electrode active material such as graphite or carbon to a second electrode current collector made of a metal foil such as copper or nickel, and may include a second electrode uncoated portion 112 as a region where the second electrode active material is not applied.

[0045] The second electrode uncoated portion 112 may be formed to overlap at the same position when the second electrode plates are stacked, thereby constituting a multi-tab structure. The second electrode uncoated portion 112 may be formed to protrude from the other side of the electrode assembly 110, and a plurality of second electrode uncoated portions may be welded to each other to form a single second current collecting tab.

[0046] The separator may be located between the first electrode plate and the second electrode plate to prevent short circuit and allow lithium ions to move. The separator may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. The material of the separator may not limit the scope of the present disclosure.

[0047] The electrode assembly 110 may be received in the housing 150 together with an electrolyte. The electrolyte may include an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC); and a lithium salt such as LiPF6 or LiBF4. The electrolyte may be liquid, solid, or gel.

[0048] The current collecting units 120 , 130 may include a first current collecting unit 120 electrically connected to the first electrode plate and a second current collecting unit 130 electrically connected to the second electrode plate.

[0049] The first current collecting unit 120 may be made of a conductive material such as aluminum, and may be electrically connected to the first electrode plate by contacting the first electrode uncoated portion 111 protruding from one end of the electrode assembly 110. The first current collecting unit 120 may include a first terminal connection portion 121 and a first electrode connection portion 125. A bending area may be formed between the first terminal connection portion 121 and the first electrode connection portion 125.

[0050] The first terminal connection portion 121 may be located above the electrode assembly 110 and may be formed parallel to the cap plate 161 to be described below. The first terminal connection portion 121 may be located between the electrode assembly 110 and the cap plate 161 and may be formed in the shape of a substantially flat plate. The first terminal 164 to be described below may be coupled to the first terminal connection portion 121. The first electrode connection portion 125 may be bent at one end of the first terminal connection portion 121 and may extend downward. The first electrode connection portion 125 may be formed on one side of the electrode assembly 110. The first electrode connection portion 125 may be coupled to the first electrode uncoated portion 111 directly or via an auxiliary tab 140, which may be optionally coupled to the first electrical connection portion 125.

[0051] The second current collecting unit 130 may be made of a conductive material such as nickel, and may be electrically connected to the second electrode plate by contacting the second electrode uncoated portion 112 protruding from the other end of the electrode assembly 110. The second current collecting unit 130 may include a second terminal connection portion 131 and a second electrode connection portion 135. A bending area may be formed between the second terminal connection portion 131 and the second electrode connection portion 135. The second terminal 165 may be electrically connected to the second terminal connection portion 131, and the auxiliary tab 140 may be optionally coupled to the second electrode connection portion 135. The second terminal connection portion 131 may be coupled to the second electrode uncoated portion 112 directly or via the auxiliary tab 140. The second current collecting unit 130 is identical in shape to the first current collecting unit 120, and thus a repeated description thereof will be omitted.

[0052] The auxiliary tab 140 may be electrically coupled to each of the first electrode connection portion 125 and the second electrode connection portion 135. The auxiliary tabs 140 coupled to the first electrode connection portion 125 and the second electrode connection portion 135 may have the same shape and may be made of different materials. For example, the auxiliary tab 140 coupled to the first electrode connection portion 125 may be made of aluminum or an aluminum alloy, and the auxiliary tab 140 coupled to the second electrode connection portion 135 may be made of copper or a copper alloy. Because the other configurations of the auxiliary tabs 140 are the same, the auxiliary tab 40 coupled to the first electrode connection portion 125 will be described hereinafter by way of example.

[0053] One end of the auxiliary tab 140 may be fixed to the first electrode connection portion 125 by welding. The auxiliary tab 140 and the first electrode connection portion 125 may be welded to each other using laser welding, resistance welding, ultrasonic welding, or the like. The other end of the auxiliary tab 140 may have an L shape bent from the first electrode connection portion 125. The first electrode uncoated portion 111 of the electrode assembly 110 may be welded to the other end of the auxiliary tab 140. In the case of welding the first electrode uncoated portion 111, the auxiliary tab 140 may be bent again so that the first electrode uncoated portion 111 faces the housing 150 outside the second electrode connection portion 135. The auxiliary tab 140 and the first electrode uncoated portion 111 may be sequentially located between the electrode assembly 110 and the housing 150 from the electrode assembly 110.

[0054] The auxiliary tab 140 may be integrally formed with the first and second electrode connecting portions 125 and 135. Alternatively, the auxiliary tab 140 may not be provided, and the first and second electrode uncoated portions 111 and 112 may be directly welded to the first and second electrode connecting portions 125 and 135, respectively.

[0055] The housing 150 may be made of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. The housing 150 may have an upper opening configured to allow the electrode assembly 110 to be inserted and placed through the upper opening; and a lower opening corresponding to the upper opening, thereby having an overall hexahedral shape without a top and a bottom. The cover plate 161 may be coupled to the upper opening of the housing 150 to seal the housing 150. The inner surface of the housing 150 may be substantially insulated to prevent an electrical short circuit from occurring therein. In other embodiments, one electrode of the electrode assembly 110 may be electrically connected to the housing 150 via the cover plate 161. The inner surface of the housing 150 may be insulated to prevent an electrical short circuit from occurring therein. For example, the housing 150 may operate as a positive electrode.

[0056] The cap assembly 160 may be coupled to the upper opening of the case 150. The cap assembly 160 may include a cap plate 161, an electrolyte inlet 162, a first terminal 164, a second terminal 165, a gasket 166, a first terminal plate 167, a second end plate 168, a fastening plate 169, and a lower insulating member 170.

[0057] The cap plate 161 may seal the upper opening of the case 150 and may be made of the same material as the case 150. For example, the cap plate 161 may be coupled to the case 150 by laser welding. The cap plate 161 may be electrically independent or electrically connected to one of the first current collecting unit 120 and the second current collecting unit 130.

[0058] An electrolyte inlet 162 for injecting electrolyte may be formed in the cap plate 161. The electrolyte may be injected into the case 150 through the electrolyte inlet 162, and then the electrolyte inlet 162 may be sealed by a plug 162a.

[0059] Each of the first terminal 164 and the second terminal 165 may be formed so as to extend through the cap plate 161. The first terminal 164 may be coupled to the first terminal connection portion 121 and may be electrically connected to the first current collecting unit 120. The second terminal 165 may be coupled to the second terminal connection portion 131 and may be electrically connected to the second current collecting unit 130.

[0060] The gasket 166 may be formed between the first terminal 164 and the second terminal 165 and the cap plate 161. The gasket 166 may be formed so as to wrap the outer side of each of the first terminal 164 and the second terminal 165 and may be made of an insulating material. The gasket 166 may be sealed between the first terminal 164 and the second terminal 165 and the cap plate. The gasket 166 may prevent external moisture from penetrating into the secondary battery 100, or may prevent leakage of an electrolyte received in the secondary battery 100.

[0061] The first terminal plate 167 may be coupled to the first terminal 164 protruding above the cap plate 161. After the first terminal plate 167 is coupled to the first terminal 164, the first terminal plate 167 may be fixed to the first terminal 164 by riveting an upper portion of the first terminal 164 or by welding an interface therebetween.

[0062] The second terminal plate 168 may be coupled to the second terminal 165 protruding above the cap plate 161. After the second terminal plate 168 is coupled to the second terminal 165, the second terminal plate 168 may be fixed to the second terminal 165 by riveting an upper portion of the second terminal 165 or by welding an interface therebetween.

[0063] The fastening plate 169 may be formed between the cap plate 161 and the first terminal plate 167 and between the cap plate 161 and the second terminal plate 168. Each of the fastening plates 169 may be made of an insulating material, or only one of the fastening plates may be made of a conductive material. For example, the fastening plate 169 located below the first terminal plate 167 may be made of a conductive material, and the fastening plate 169 located below the second terminal plate 168 may be made of an insulating material. The first terminal 164 may have the same polarity as the cap plate 161. If each of the fastening plates 169 is made of an insulating material, the first terminal 164 and the second terminal 165 may be electrically isolated from the cap plate 161.

[0064] A lower insulating member 170 may be formed between the first current collecting unit 120 and the cap plate 161 and between the second current collecting unit 130 and the cap plate 161 to electrically insulate the first and second current collecting units 120 and 130 from the cap plate 161 .

[0065] The sealing plate 180 may be configured to seal the lower opening of the housing 150. The sealing plate 180 may be rectangular in shape so as to correspond to the lower opening of the housing 150, and may be coupled along the opening of the housing 150 by welding W. In order to facilitate welding and increase coupling force, the sealing plate 180 may be made of the same material as the housing 150.

[0066] The sealing plate 180 may be connected to the housing 150 by welding W at a position where the edge area 181 of the sealing plate 180 is connected to the housing 150 along the lower opening of the housing 150. The welding strength may be determined according to the depth of the welding W. The depth of the welding W at the edge area 181 of the sealing plate 180 may be set to 300um to 400um. At this depth, the connection between the sealing plate 180 and the housing 150 may be maintained until the pressure reaches a predetermined pressure, and if the pressure exceeds the predetermined pressure, the sealing plate 180 and the housing 150 may be separated from each other. If the depth is set to 300um to 400um for welding the sealing plate 180, the rupture pressure of the sealing plate 180 may be set to 7bar to 10bar. If the rupture pressure is 7bar or more, the pressure resistance of the housing 150 and the sealing plate 180 may be guaranteed to maintain the stability of operation under normal conditions. If the rupture pressure is set to 10bar or less, the sealing plate 180 may be opened at the same level as the operation of the existing vent when an event occurs in the battery cell.

[0067] In the secondary battery 100 according to the embodiment, the sealing plate 180 may be broken from the lower end of the housing 150 when an event occurs, rather than providing a separate exhaust member in the cap plate 160. If the internal pressure of the housing 150 reaches the set fracture pressure, at least three of the four sides of the sealing plate 180 connected to the housing 150 may be broken simultaneously due to the internal pressure. The sealing plate 180 can open the lower end of the housing 150, and the electrode assembly 110 in the housing 150 can be exposed downward. If the lower part of the housing 150 is opened when the housing 150 is under pressure, the electrode assembly 110 can be pushed in the opening direction. The electrode assembly 110 can be connected to the auxiliary tab 140 (or to the current collector 120, 130 if the auxiliary tab 140 is not provided separately) via the first electrode uncoated portion 111 and the second electrode uncoated portion 112, each of which can be formed in the shape of a relatively thin foil. The portion where the first electrode uncoated portion 111 and the second electrode uncoated portion 112 of the electrode assembly 110 are welded to the auxiliary tab 140 may be broken, whereby the electrode assembly 110 may be separated from the auxiliary tab 40 and may be discharged from the housing 150 through the opened lower portion of the housing 150. The electrode assembly 110 ignited in the battery cell where the incident occurred may be discharged to the outside of the housing 150 and, although not separately shown, may be received in an external cooling / extinguishing solvent, etc. The electrode assembly 110 may be separated and discharged from the battery cell where the incident occurred, thereby preventing heat from being propagated to adjacent battery cells.

[0068] In the secondary battery 100 according to the embodiment, as described above, if the internal pressure of the battery cell where the event occurs reaches a predetermined rupture pressure, the sealing plate 180 can be ruptured from the shell 150, so that the electrode assembly 110 can be discharged to the bottom of the shell 150 and can be quickly separated from the surrounding battery cells to prevent heat spread.

[0069] Hereinafter, an operation of a secondary battery according to an embodiment will be described in more detail.

[0070] Figure 5 FIG. 1 shows a change in temperature over time when an event occurs in a secondary battery according to an embodiment.

[0071] See also Figure 5 , the temperature of the lower surface of the cell 1 where the event occurred can be compared with the temperature of the lower surface of the adjacent cell 2. If an event occurs in the battery 1, the temperature may quickly rise to about 270 degrees. As described above, the electrode assembly 110 of the cell 1 can be discharged through the lower part of the case 150, and the temperature of the cell 1 can fall back from 270 degrees.

[0072] The temperature of cell 2 may initially rise to about 80 degrees in response to an event in cell 1, but the temperature of cell 2 may no longer rise, and then the temperature of cell 2 may gradually decrease. Experiments have shown that heat caused by an event in cell 1 can be prevented from propagating to adjacent cells 2.

[0073] Hereinafter, a configuration of a secondary battery according to another embodiment will be described.

[0074] Figure 6 is a perspective view showing a secondary battery according to another embodiment. Figure 7a It is along Figure 6 A cross-sectional view taken along line BB'. Figure 7b yes Figure 7a An enlarged view of part P. Figure 8 is a partial cross-sectional view illustrating a coupling relationship between an electrode assembly and an electrode terminal in a secondary battery according to another embodiment. Fig. 9 is a partial perspective view illustrating a coupling relationship between an electrode assembly and an insulating plate in a secondary battery according to another embodiment.

[0075] See also Figure 6 to Figure 9 , a secondary battery 200 according to another embodiment may include an electrode assembly 210 , a case 250 , a cap assembly 260 , and a sealing plate 280 .

[0076] The electrode assembly 210 may be formed by winding or stacking a laminate including a first electrode plate, a separator, and a second electrode plate, each of which may be formed as a thin plate or a film. In the previous embodiment, the first electrode uncoated portion 111 and the second electrode uncoated portion 112 may be formed at the upper portion of the electrode assembly 110. In a secondary battery 200 according to another embodiment, the first electrode uncoated portion 211 and the second electrode uncoated portion 212 of the electrode assembly 210 may be formed at opposite sides of the electrode assembly 210, respectively. As required, a fixing band 212a may be further formed at the stacking edge of the electrode assembly 210. Except for the orientation of the electrode uncoated portions 211, 212, this embodiment may be identical in construction to the previous embodiment.

[0077] The case 250 may be made of a conductive metal such as aluminum, aluminum alloy, or nickel-plated steel, and may be open at opposite sides and a bottom thereof. The cap assembly 260 may be coupled to opposite sides of the case 250 to form positive and negative terminals.

[0078] The cap assembly 260 may be coupled to the opening formed in the opposite side of the case 250. The cap assembly 260 may be electrically coupled to the first electrode uncoated portion 211 and the second electrode uncoated portion 212 of the electrode assembly 210. The cap assembly 260 may include a cap plate 261, an electrolyte inlet 262, a first terminal 264, a second terminal 265, a gasket 266, a first terminal plate 267, a second terminal plate 268, a fastening plate 269, and a lower insulating member 270.

[0079] The cap plate 261 may seal openings formed at each of opposite ends of the case 250, and may be made of the same material as the case 250. An electrolyte inlet 262 for injecting an electrolyte may be formed in the cap plate 261.

[0080] Each of the first terminal 264 and the second terminal 265 may be formed so as to extend through the cap plate 261. The first terminal 264 may be electrically connected to the first electrode uncoated portion 211. The second terminal 265 may be electrically connected to the second electrode uncoated portion 212.

[0081] A gasket 266 may be formed between each of the first terminal 264 and the second terminal 265 and the cap plate 261 .

[0082] The first terminal plate 267 may be coupled to the first terminal 264 protruding above the cap plate 261. The second terminal plate 268 may be coupled to the second terminal 265 protruding above the cap plate 261.

[0083] The fastening plates 269 may be formed between the cap plate 261 and the first terminal plate 267 and between the cap plate 261 and the second terminal plate 268. Each of the fastening plates 269 may be made of an insulating material, or only one of the fastening plates may be made of a conductive material.

[0084] A lower insulating member 270 may be formed between the first current collecting unit 220 and the cap plate 261 and between the second current collecting unit 230 and the cap plate 261 to electrically insulate the first and second current collecting units 220 and 230 from the cap plate 261 .

[0085] The sealing plate 280 may be coupled to an opening at the lower portion of the housing 250. The shape of the sealing plate 280 may be rectangular so as to correspond to the lower opening of the housing 250, and may be coupled by welding along the opening of the housing 250. If the sealing plate 280 is coupled to the housing 250 by welding W at a position where the sealing plate 280 is connected to the housing 250 along the lower opening of the housing 250, the welding strength may be determined according to the depth of the welding W. In the secondary battery 200 according to another embodiment, the depth of the welding W at the sealing plate 280 may be set to 300um to 400um. If the depth is set to 300um to 400um for welding the sealing plate 280, the rupture pressure of the sealing plate 280 may be set to 7bar to 10bar. If the rupture pressure is 7bar or more, the pressure resistance of the housing 250 and the sealing plate 280 may be ensured to maintain the stability of operation under normal conditions. If the rupture pressure is set to 10 bar or less, the sealing plate 280 may be opened at the same level as the operation of an existing vent when an event occurs in the battery cell.

[0086] Because each of the first electrode uncoated portion 211 and the second electrode uncoated portion 212 of the electrode assembly 210 can be formed in the shape of a thin foil and welded to the corresponding terminals 264, 265, the first electrode uncoated portion 211 and the first electrode uncoated portion 212 can be separated and discharged to the bottom of the shell 150 when the sealing plate 280 is opened.

[0087] In a secondary battery 200 according to another embodiment, as described above, if the internal pressure of a battery cell where an event occurs reaches a predetermined rupture pressure, the sealing plate 280 can be ruptured from the shell 250 so that the electrode assembly 210 can be discharged to the bottom of the shell 250 and can be quickly separated from the surrounding battery cells to prevent heat spread.

[0088] The above is merely one embodiment for implementing the secondary battery according to the present disclosure, and the present disclosure is not limited to the above embodiment, and the technical spirit of the present disclosure lies in that any ordinary technician in the field to which the present disclosure belongs can make various modifications without departing from the main purpose of the present disclosure as claimed in the attached claims.

Claims

1. A secondary battery comprising: an electrode assembly including a first electrode plate and a second electrode plate, each of the first electrode plate and the second electrode plate having an electrode uncoated portion protruding from at least one side of the electrode assembly; a housing configured to receive the electrode assembly, the housing having an opening formed in a lower end of the housing; a cap assembly formed at one surface of the housing, the cap assembly being configured to seal the housing, the cap assembly comprising an electrode terminal electrically connected to the electrode uncoated portion; as well as A sealing plate is coupled along a periphery of the opening formed in the lower end of the housing. 2 . The secondary battery according to claim 1 , wherein the sealing plate is coupled along the periphery of the opening by welding. 3 . The secondary battery according to claim 1 , wherein the sealing plate is welded along the periphery of the opening at a welding depth of 300 um to 400 um. 4 . The secondary battery according to claim 1 , wherein a rupture pressure of the sealing plate sealed with respect to the case is set to 7 bar to 10 bar. 5 . The secondary battery according to claim 1 , wherein the case has a larger area than the electrode assembly, the case is provided with the opening at the lower end of the case, and the case is sealed by the sealing plate.

6. The secondary battery according to claim 1, wherein If the internal pressure of the housing reaches a predetermined rupture pressure, at least three sides of the sealing plate rupture from the opening of the housing.

7. The secondary battery according to claim 6, wherein If the sealing plate is broken from the case, the electrode assembly is separated from the cap assembly and falls off from the case.

8. The secondary battery according to claim 6, wherein If the sealing plate is broken from the case, the electrode assembly is separated from the cap assembly at a portion where the electrode assembly and the cap assembly are welded to each other.

9. The secondary battery according to claim 1, wherein the case is provided with an opening at each of an upper portion and a lower portion of the case, The cover assembly is coupled to the upper opening, and The sealing plate is coupled to the lower opening.

10. The secondary battery according to claim 9, wherein the cap assembly includes a cap plate configured to seal the upper opening of the case and an electrode terminal extending through the cap plate to be electrically connected to the electrode assembly, and The sealing plate is coupled to the cover plate at a position corresponding to the cover plate. The secondary battery according to claim 10 , wherein the cap plate is not provided with a vent.

12. The secondary battery according to claim 1, wherein the case is provided with an opening at each of opposite sides and a lower portion of the case, The cover assembly is coupled to each of the side openings, and The sealing plate is coupled to the lower opening.

13. The secondary battery according to claim 12, wherein the cap assembly includes a pair of cap plates configured to seal the side opening of the case and an electrode terminal extending through each of the cap plates to be electrically connected to the electrode assembly, and The sealing plate is coupled between the pair of cover plates so as to correspond to the pair of cover plates. 14 . The secondary battery according to claim 13 , wherein the electrode assembly is located between the pair of cap plates, and the sealing plate is positioned to correspond to a lower portion of the electrode assembly. 15 . The secondary battery according to claim 14 , wherein both ends of the electrode assembly are respectively coupled to the pair of cap plates.

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