Bottom exhaust secondary battery, method of manufacturing same, and vehicle including same

Abstract

Disclosed herein are a secondary battery and a method of manufacturing the same, the secondary battery including a vent hole through which gas can be discharged in the case of an internal event, and the vent hole providing a structure for securing a gas passage within a bottom-vented secondary battery, the present invention aims to avoid damage to a case (can) in the event of an event or during thermal runaway due to an increase in a degassing path in a secondary battery. To this end, provided are a secondary battery, a method of manufacturing the same, and a vehicle including the same, the secondary battery including: a case; an electrode assembly in the case; a first cover plate coupled to the housing; the exhaust port is opposite to the first cover plate; and a gap holding part for holding a gap between the electrode assembly and the exhaust port.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0143655 filed in the Korean Intellectual Property Office on October 25, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] Aspects of embodiments of the present disclosure relate to a secondary battery and a method of manufacturing the secondary battery. Background Art

[0003] Unlike primary batteries, which are not designed to be (re)charged, secondary (or rechargeable) batteries are batteries that are designed to be discharged and recharged. Low-capacity secondary batteries can be used in portable small electronic devices such as smartphones, feature phones, notebook computers, digital cameras, and video cameras, while large-capacity secondary batteries can be widely used as power sources for driving motors in hybrid and electric vehicles and for storing electricity (e.g., home and / or utility-scale power storage).

[0004] A secondary battery generally includes an electrode assembly consisting of a positive electrode and a negative electrode, a case accommodating the electrode assembly, and an electrode terminal connected to the electrode assembly.

[0005] The above information disclosed in this Background section is for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute related (or prior) art. Summary of the invention

[0006] Aspects of embodiments of the present disclosure are directed to a secondary battery including a vent hole through which gas is exhausted in the event of an internal event, and a method of manufacturing the secondary battery.

[0007] In the case of a bottom vented secondary battery (e.g., a so-called tall battery having an extended vertical length / height) having a vent installed at the bottom of its housing, the housing (tank) may be destroyed in the event of an incident or during thermal runaway due to an increase in degassing paths.

[0008] Various embodiments propose a structure for securing a gas channel within a secondary battery, thereby improving degassing performance of the secondary battery.

[0009] In one or more embodiments, a secondary battery is provided, comprising: a shell; an electrode assembly in the shell; a first cover plate coupled to the shell; an exhaust port opposite to the first cover plate; and a gap maintaining portion for maintaining a gap between the electrode assembly and the exhaust port.

[0010] The gap maintaining part may be in the case, and may face the electrode assembly.

[0011] The secondary battery may further include a second cap plate opposite to the first cap plate, wherein the exhaust port is on the second cap plate, and wherein the gap maintaining part is on a surface of the second cap plate facing the electrode assembly.

[0012] The gap between the electrode assembly and the exhaust port may be about 0.7 mm or more.

[0013] The gap maintaining portion may include two or more parts.

[0014] The gap maintaining portion may include two or more portions symmetrically positioned with respect to the exhaust port.

[0015] The secondary battery may include a cylindrical secondary battery.

[0016] The secondary battery may include a prismatic secondary battery.

[0017] The case may have a prismatic battery shape having a pair of opposing short sides and a pair of opposing long sides, wherein the gap maintaining portion includes a linear protrusion extending in a direction perpendicular to the short sides.

[0018] The case may have a prismatic battery shape having a pair of opposing short sides and a pair of opposing long sides, wherein the gap maintaining portion is a linear protrusion extending in a direction perpendicular to the long sides of the case.

[0019] The gap maintaining portion may be a protrusion protruding toward the electrode assembly.

[0020] In one or more embodiments, a method for manufacturing a secondary battery is provided, the method comprising: providing an electrode assembly; providing a shell for accommodating the electrode assembly; coupling a first cover plate to the shell; forming an exhaust port at a position opposite to the first cover plate; and forming a gap maintaining portion, the gap maintaining portion being configured to maintain a gap between the electrode assembly and the exhaust port.

[0021] The gap maintaining portion may be at a surface of the case opposite to the first cap plate and facing the electrode assembly.

[0022] The method may further include installing a second cover plate in the case opposite to the first cover plate, wherein the exhaust port is on the second cover plate, and wherein the gap maintaining portion is on a surface of the second cover plate facing the electrode assembly.

[0023] The gap between the electrode assembly and the exhaust port may be about 0.7 mm or more.

[0024] The gap maintaining portion may include two or more parts.In one or more embodiments, there is provided a vehicle including the secondary battery / one or more secondary battery packs having the above-described configuration.

[0025] However, the present disclosure is not limited to the above, and other aspects not specifically mentioned herein and aspects of the present disclosure to solve these problems will be clearly understood by those skilled in the art from the following description of the present disclosure.

[0026] According to an embodiment of the present disclosure, in a bottom exhaust secondary battery (especially a cylindrical secondary battery, a prismatic secondary battery or a button-type secondary battery (so-called tall battery) having an extended vertical length relative to its horizontal length), by maintaining a constant distance (for example, about 0.7 mm or greater) between the facing surface of the cover assembly (including the first cover plate) of the sealed shell and the electrode assembly therein, it is possible to ensure a gas exhaust channel in the event of an event or during thermal runaway, thereby improving the degassing performance.

[0027] In a vehicle equipped with a secondary battery having a vent at its bottom according to the present disclosure, even in the event of an incident or during thermal runaway, degassing can be performed at the bottom of the vehicle (e.g., toward the ground), which can promote the safety of passengers. Since a gas exhaust passage can be always ensured, safety can be further enhanced.

[0028] However, aspects of the present disclosure are not limited to the aspects and features described above, and other aspects not mentioned will be clearly understood by those skilled in the art from the detailed description described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings attached to this specification illustrate embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the accompanying drawings: Figure 1 is a cross-sectional view of a cylindrical secondary battery; Figure 2A is a top perspective view of a prismatic secondary battery; Figure 2B It is along Figure 2A A cross-sectional view taken along line II'; Figure 3A is a schematic diagram of a prismatic secondary battery as a bottom exhaust secondary battery according to one or more embodiments of the present disclosure; Figure 3B is a schematic diagram of a prismatic secondary battery as a bottom exhaust secondary battery according to one or more other embodiments of the present disclosure; Figure 4 yes Figure 3A and Figure 3B A schematic cross-sectional view of a bottom vented secondary battery shown in ; Figure 5 is a graph showing the relationship between the bottom space (gap) and the internal pressure; Fig. 6A is a schematic cross-sectional view of a bottom exhaust secondary battery according to one or more embodiments of the present disclosure; Figure 6B is a schematic cross-sectional view of a bottom exhaust secondary battery according to one or more other embodiments of the present disclosure; Fig. 7A and Figure 7B are a plan view and a perspective view respectively showing an example of a gap maintaining portion; Fig. 8A and Figure 8B are a plan view and a perspective view respectively showing another example of the gap maintaining portion; Fig.9A and Fig. 9B are a plan view and a perspective view respectively showing still another example of the gap maintaining portion; Fig.10 is an exemplary diagram of a secondary battery module in which prismatic secondary batteries are arranged according to one or more embodiments of the present disclosure; Fig.11 Yes Fig.10 A diagram of a secondary battery pack of a secondary battery module shown in ; and Fig.12 Yes Fig.11 Conceptual diagram of a vehicle with a secondary battery pack shown in FIG. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be restrictively interpreted as ordinary meanings or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical ideas of the present disclosure based on the principle that the inventor can act as his or her own lexicon compiler to appropriately define the concepts of the terms in order to describe his or her invention in the best manner.

[0031] The embodiments described in this specification and the configurations shown in the accompanying drawings are only some of one or more embodiments of the present disclosure, and do not represent all aspects of the present disclosure. Therefore, it should be understood that when submitting this application, there may be various equivalents and modifications that can replace or modify one or more embodiments described herein.

[0032] It will be understood that if an element or layer is referred to as being "on," "connected to," or "bound to" another element or layer, the element or layer may be directly on, directly connected to, or directly bound to the other element or layer, or one or more intervening elements or layers may also be present. When an element or layer is referred to as being "directly on," "directly connected to," or "directly bound to" another element or layer, there are no intervening elements or layers. For example, if a first element is described as being "bound to" or "connected to" a second element, the first element may be directly bound to or directly connected to the second element, or the first element may be indirectly bound to or indirectly connected to the second element via one or more intervening elements.

[0033] In the figure, for the sake of clarity, the sizes of various elements, layers, etc. may be exaggerated. The same reference numerals represent the same elements. As used herein, the term "and / or" includes any combination and all combinations of one or more of the relevant listed items. In addition, if the embodiment of the present disclosure is described, the use of "may (may)" relates to "one or more embodiments of the present disclosure". The expressions such as "at least one (kind / person) in ... " and "any one (kind / person) in ... " modify the entire column of elements without modifying the individual elements in the column when the expression is after a column of elements. When phrases such as "at least one (kind / person) in A, B and C", "at least one (kind / person) in A, B or C", "at least one (kind / person) selected from the group of A, B and C" or "at least one (kind / person) selected from A, B and C" are used to represent a column of elements A, B and C, the phrase can refer to any suitable combination (or subset) and all suitable combinations (or subsets) in A, B and C, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term "use" and variations thereof may be considered synonymous with the term "utilize" and variations thereof, respectively. As used herein, the terms "substantially," "approximately," and similar terms are used as terms of approximation rather than as terms of degree, and are intended to account for the inherent deviations in measurements or calculations that one of ordinary skill in the art would recognize.

[0034] It will be understood that, although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teaching of the exemplary embodiment, the first element, first component, first region, first layer or first part discussed below can be referred to as the second element, second component, second region, second layer or second part.

[0035] For ease of description, spatially relative terms such as "under", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature to another element or features as shown in the figure. It will be understood that in addition to the orientation depicted in the figure, the spatially relative terms are also intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, the elements described as "under" or "below" other elements or features will then be oriented to be "above" or "on" the other elements or features. Therefore, the term "under" can cover both above and below. The device can be oriented otherwise (e.g., rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0036] The terms used herein are for the purpose of describing the embodiments of the present disclosure and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "one" and "a (kind / person)" are also intended to include plural forms. It will also be understood that if the terms "include", "comprise" and / or variations thereof are used in this specification, the stated features, integers, steps, operations, elements and / or components are indicated, but the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their groups are not excluded.

[0037] In addition, any numerical range disclosed and / or described herein is intended to include all sub-ranges of the same numerical precision contained in the described range. For example, the range of "1.0 to 10.0" is intended to include all sub-ranges between the described minimum value 1.0 and the described maximum value 10.0 (and including the described minimum value 1.0 and the described maximum value 10.0), that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6 as an example. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to modify this specification and the claims to clearly describe any sub-range contained in the scope clearly described here. All such ranges are intended to be inherently described in this specification so that the modification of any such sub-range clearly described will meet the requirements.

[0038] Referring to two compared elements, features, etc. as "the same" may mean that they are "substantially the same." Thus, the phrase "substantially the same" may include situations with deviations that are considered low in the art (e.g., 5% or less). Additionally, if a parameter is referred to as being uniform in a given area, this may mean that it is uniform in terms of average value.

[0039] Throughout the specification, unless otherwise specified, each element may be in the singular or in the plural.

[0040] Arranging an arbitrary element “on (or under)” or “on (under)” another element may mean that the arbitrary element may contact the upper (or lower) surface of the another element, and another element may also be interposed between the another element and the arbitrary element positioned on (or under) the element.

[0041] In addition, it will be understood that if a component is referred to as being “linked,” “coupled” or “connected” to another component, the components may be directly “linked,” “coupled” or “connected” to each other or the other component may be “interposed” between the components.

[0042] Throughout the specification, unless otherwise stated, if "A and / or B" is stated, it means A, B, or A and B. That is, "and / or" includes any combination or all combinations of multiple listed items. Unless otherwise stated, when "C to D" is stated, it means C or greater and D or less.

[0043] The terms used herein are for the purpose of describing embodiments of the present disclosure and are not intended to be limiting of the present disclosure.

[0044] Examples of secondary batteries include coin type, cylindrical type, prismatic type, pouch type, etc. The present disclosure may be applied to cylindrical and prismatic secondary batteries. Before describing an embodiment of the present disclosure, cylindrical and prismatic secondary batteries will first be briefly described.

[0045] Figure 1 A cylindrical secondary battery is shown. Figure 1 As shown in , the secondary battery includes an electrode assembly 30, a case 10 accommodating the electrode assembly 30 and an electrolyte therein, a cap assembly 50 coupled to an opening of the case 10 to seal the case 10, and an insulating plate 37 positioned between the electrode assembly 30 and the cap assembly 50 inside the case 10.

[0046] The electrode assembly 30 may include a first electrode 33 and a second electrode 31 with a separator 32 therebetween, and may be wound into a core shape.

[0047] The first electrode 33 may include a first substrate and a first active material layer on the first substrate. The first lead tab 35 may extend outward from a first uncoated portion of the first substrate where the first active material layer is not located. The first lead tab 35 may be electrically connected to the cap assembly 50.

[0048] The second electrode 31 may include a second substrate and a second active material layer on the second substrate. The second lead tab 34 may extend outward from a second uncoated portion of the second substrate where the second active material layer is not located, and the second lead tab 34 may be electrically connected to the housing 10. The first lead tab 35 and the second lead tab 34 may extend in opposite directions.

[0049] The first electrode 33 may be used as a positive electrode. In such an embodiment, the first substrate may be made of, for example, aluminum foil, and the first active material layer may include, for example, a transition metal oxide. The second electrode 31 may be used as a negative electrode. In such an embodiment, the second substrate may be made of, for example, copper foil or nickel foil, and the second active material layer may include, for example, graphite.

[0050] The separator 32 reduces or prevents the possibility of a short circuit between the first electrode 33 and the second electrode 31 while allowing lithium ions to move between the first electrode 33 and the second electrode 31. The separator 32 may be made of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, or the like.

[0051] The case 10 accommodates the electrode assembly 30 and the electrolyte, and forms the appearance of the secondary battery together with the cap assembly 50. The case 10 may have a substantially cylindrical body portion 12 and a bottom portion 11 connected to one side (e.g., one end) of the body portion 12. An inwardly deformed curling portion 13 (e.g., curling) may be formed in the body portion 12, and an inwardly bent crimping portion 15 (e.g., crimping piece) may be formed at an open end of the body portion 12.

[0052] The crimping portion 13 can reduce or prevent movement of the electrode assembly 30 inside the case 10 and can facilitate seating of the gasket and cap assembly 50. The crimping portion 15 can securely fix the cap assembly 50 by pressing the edge of the case 10 against the gasket 14. The case 10 can include, for example, nickel-plated iron.

[0053] The cap assembly 50 may be fixed to the inside of the crimping part 15 by the gasket 14 to seal the housing 10. The cap assembly 50 may include an upper cap, a safety vent, a lower cap, an insulating member, and a sub-board, but the cap assembly is not limited thereto and may be modified in various ways.

[0054] The upper cover may be positioned at the uppermost portion of the cap assembly 50. The upper cover may include a terminal portion protruding upward and connected to an external circuit, and an outlet for exhausting gas may be arranged around the terminal portion.

[0055] The safety vent may be positioned below the upper cover. The safety vent may include a protrusion that protrudes downward and is connected to the daughter board, and at least one notch may be formed in the safety vent around the protrusion.

[0056] If gas is generated due to overcharging or abnormal operation of the secondary battery, the protrusion may be deformed upward due to pressure and may be separated from the sub-plate, while the safety vent is cut (e.g., ruptured or torn) along the notch. The cut safety vent can reduce the possibility of preventing the secondary battery from exploding by allowing gas to be discharged to the outside.

[0057] The lower cover may be below the safety vent. The lower cover may have a first opening for exposing a protrusion of the safety vent, and may have a second opening for gas discharge. An insulating member may be positioned between the safety vent and the lower cover to insulate the safety vent from the lower cover.

[0058] The sub-plate may be below the lower cover. The sub-plate may be fixed to the lower surface of the lower cover to block the first opening of the lower cover. The protrusion of the safety vent may be fixed to the sub-plate. The first lead tab 35 that may be led out from the electrode assembly 30 may be fixed to the sub-plate. In one or more embodiments, the upper cover, the safety vent, the lower cover, and the sub-plate may be electrically connected to the first electrode 33 of the electrode assembly 30.

[0059] The insulating plate 37 may be positioned to contact the electrode assembly 30 below the curling portion 13. The insulating plate 37 may have a tab opening through which the first lead tab 35 is led out. The cap assembly 50 electrically connected to the first electrode 33 through the first lead tab 35 may face the electrode assembly 30, and the insulating plate 37 is placed between the cap assembly 50 and the electrode assembly 30. The cap assembly 50 may be kept insulated (e.g., electrically insulated) from the electrode assembly 30 by the insulating plate 37. In one or more embodiments, another insulating plate 36 may be included for insulation between the electrode assembly 30 and the bottom 11 of the case 10.

[0060] Figure 2A is a top perspective view of a prismatic secondary battery. Figure 2B It is along Figure 2A A cross-sectional view taken along line II'.

[0061] First, we will describe Figure 2A Appearance of a prismatic secondary battery shown in FIG.

[0062] The case 51 defines the overall appearance of the prismatic secondary battery and may be made of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. In one or more embodiments, the case 51 may provide a space therein for accommodating an electrode assembly.

[0063] The cap assembly 60 may include a cap plate 61 covering the opening of the housing 51, and the cap assembly 60 and the cap plate 61 may be made of a conductive material. Here, the first terminal 62 and the second terminal 63 may be electrically connected to the corresponding positive electrode and negative electrode (or negative electrode and positive electrode) inside the housing, and may be installed to protrude outward through the cap plate 61.

[0064] The cap plate 61 may be provided with an electrolyte injection port 64 for installing a sealing plug (or a sealing pin) and an exhaust port 66 formed with a notch 65. The exhaust port 66 may exhaust gas generated inside the secondary battery.

[0065] Reference Figure 2B , the internal structure of the prismatic secondary battery and the coupling structure with the cap assembly 60 will be described.

[0066] like Figure 2B As shown in , a prismatic secondary battery may include an electrode assembly 40 , a first current collector 41 , a first terminal 62 , a second current collector 42 , a second terminal 63 , a case 51 , and a cap assembly 60 .

[0067] The electrode assembly 40 can be formed by winding or stacking a stack of a first electrode plate, a separator, and a second electrode plate formed into a thin plate or a film. If the electrode assembly 40 is a winding stack, the winding axis can be parallel to the length direction of the shell 51. In other embodiments, the electrode assembly 40 can be a stacking type instead of a winding type, and in the present disclosure, the shape of the electrode assembly 40 is not limited. In one or more embodiments, the electrode assembly 40 can be a Z stacking electrode assembly, in which the positive electrode plate and the negative electrode plate are respectively inserted into both sides of the separator bent into the Z stack. In one or more embodiments, one or more electrode assemblies can be stacked so that the long sides of the electrode assembly are adjacent to each other and can be accommodated in the shell, and the number of electrode assemblies in the shell is not limited in the present disclosure. The first electrode plate of the electrode assembly can be used as a negative electrode, and the second electrode plate can be used as a positive electrode. In one or more embodiments, the opposite is also possible.

[0068] The first electrode plate may be formed by applying a first electrode active material such as graphite or carbon to a first electrode current collector formed of a metal foil such as copper, copper alloy, nickel or nickel alloy. The first electrode plate may include a first electrode terminal tab 43 (e.g., a first uncoated portion) as an area where the first electrode active material is not applied. The first electrode terminal tab 43 may serve as a current flow path between the first electrode plate and the first current collector 41. In some embodiments, if the first electrode plate is manufactured, the first electrode terminal tab 43 may be formed by being cut in advance to protrude to one side of the electrode assembly 40, or the first electrode terminal tab 43 may protrude to one side of the electrode assembly 40 more than (e.g., farther than or beyond) the separator without being cut separately.

[0069] The second electrode plate may be formed by coating a second electrode active material such as a transition metal oxide on a second electrode current collector formed of a metal foil such as aluminum or an aluminum alloy. The second electrode plate may include a second electrode terminal tab 44 (e.g., a second uncoated portion) as an area where the second electrode active material is not coated. The second electrode terminal tab 44 may serve as a current flow path between the second electrode plate and the second current collector 42. In some embodiments, if the second electrode plate is manufactured, the second electrode terminal tab 44 may be formed by being cut in advance to protrude to the other side (e.g., the opposite side) of the electrode assembly, or the second electrode plate may protrude to the other side of the electrode assembly more than (e.g., farther than or beyond) the separator without being cut separately.

[0070] In some embodiments, the first electrode tab 43 may be located on the right side of the electrode assembly 40, and the second electrode tab 44 may be located on the left side of the electrode assembly 40. In other embodiments, the first electrode tab 43 and the second electrode tab 44 may be located on one side of the electrode assembly 40 in the same direction. Figure 2A The left and right sides are defined by the secondary battery oriented therein, and if the secondary battery is rotated left to right or up to down, the positions of the left and right sides may be changed.

[0071] The separator reduces or prevents the possibility of a short circuit between the first electrode plate and the second electrode plate while allowing lithium ions to move between the first electrode plate and the second electrode plate. The separator may be made of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, or the like.

[0072] The first electrode tab 43 of the first electrode plate and the second electrode tab 44 of the second electrode plate may be respectively positioned at both ends (e.g., opposite ends) of the electrode assembly 40. In some embodiments, the electrode assembly 40 may be housed in the case 51 together with the electrolyte. In one or more embodiments, in the electrode assembly 40, the first current collector 41 and the second current collector 42 may be respectively welded and connected to the first electrode tab 43 of the first electrode plate and the second electrode tab 44 of the second electrode plate exposed on both sides to be positioned at the first electrode tab 43 of the first electrode plate and the second electrode tab 44 of the second electrode plate.

[0073] As described above, in some embodiments where the first electrode tab 43 and the second electrode tab 44 are located at the top of the electrode assembly 40 , the first current collector 41 and the second current collector 42 are located at the top of the electrode assembly 40 .

[0074] The first current collector 41 and the second current collector 42 may be connected to the Figure 2A In some embodiments, the connecting members 67 may each have a threaded outer peripheral surface and may be fastened to the first terminal 62 and the second terminal 63 (eg, by screws, by riveting, or by welding).

[0075] Refer to above Figure 1 , Figure 2A and Figure 2B In the described cylindrical and prismatic secondary batteries, the vent for degassing is shown as being installed in the cap assembly 50, 60, but in one or more other embodiments, the vent may be installed at a position facing / opposite to the cap assembly 50, 60.

[0076] Hereinafter, for ease of understanding, a position where the cover assembly 50 and / or 60 exists will be referred to as “top”, and a position facing / opposite to the cover assembly 50 and / or 60 will be referred to as “bottom”.

[0077] As described above, the exhaust port installed at a position facing the cover assembly 50 and / or 60 / opposite to the cover assembly 50 and / or 60 (for example, if it is used in a hybrid vehicle or an electric vehicle), can discharge gas to the lower side of the vehicle (for example, toward the ground), thereby ensuring the safety of passengers and the environment. In this specification, a secondary battery in which the exhaust port is installed at the bottom is referred to as a "bottom exhaust secondary battery". The bottom exhaust secondary battery is suitable for a secondary battery having an extended vertical length relative to its horizontal length (a so-called tall battery), but the present disclosure is not limited thereto.

[0078] Hereinafter, an embodiment of a bottom exhaust secondary battery according to the present disclosure will be described.

[0079] Figure 3A is a schematic diagram of a prismatic secondary battery as a bottom exhaust secondary battery according to one or more embodiments of the present disclosure. Figure 2A Compared with the prismatic secondary battery shown in Figure 3A The prismatic secondary battery shown in FIG. 1 may have a structure having an extended vertical length (eg, a tall battery), but the present disclosure is not limited thereto.

[0080] The electrode assembly 200 in a core form or a stack form may be built in the case 100, and the cap assembly 300 may be located in the upper opening of the case 100. The cap assembly 300 may include a first cap plate 310, a first terminal 320a, and a second terminal 320b.

[0081] exist Figure 3A In (and in Figure 3B ), the first electrode tab 210 and the second electrode tab 220 are shown as being located on the upper surface of the electrode assembly 200 within the housing 100, but this is a conceptual illustration of an example, and the present disclosure and the following embodiments are not limited thereto. For example, there may also be a secondary battery having a side tab structure in which electrode tabs are located on both sides of the secondary battery.

[0082] The second cover plate 400 may be installed at an opening of the bottom of the housing 100 (e.g., facing or opposite to the cover assembly 300 or the first cover plate 310 as described above). The second cover plate 400 may have a vent 410 formed therein. A vent 500 that may be ruptured by gas within the housing 100 may be attached to / in the vent 410 by welding or the like.

[0083] Figure 3B is a schematic diagram of a prismatic secondary battery as a bottom exhaust secondary battery according to one or more other embodiments of the present disclosure.

[0084] Similar to Figure 3A In one or more embodiments, the electrode assembly 200 may be built into the housing 100, and the cap assembly 300 may be installed in the upper opening of the housing 100. Figure 3A The housing 100 is different, Figure 3B The housing 100 in one or more embodiments may have a bottom 110 (or referred to as “housing bottom 110 ”) connected to a side thereof and blocking a lower side thereof.

[0085] The case bottom 110 may have a vent hole 120 formed therein, and a vent port 500 that may be broken by gas within the case 100 may be attached to the vent hole 120 by welding or the like.

[0086] The cap assembly 300 may include a first cap plate 310, a first terminal 320a, and a second terminal 320b. Figure 3A In one or more embodiments, the first electrode tab 210 and the second electrode tab 220 may be located on an upper surface of the electrode assembly 200 .

[0087] As mentioned above, in Figure 3A and Figure 3B In a bottom-vented secondary battery as shown in (for example, if the battery has a tall battery structure with an extended vertical length), the case (or can) may rupture in the event of an incident or during thermal runaway due to an increase in the degassing path. It may be appropriate to ensure a gas exhaust channel to improve the degassing performance.

[0088] Will refer to Figure 4 To describe the suitability of ensuring the gas exhaust passage. Figure 4 yes Figure 3A and Figure 3B A schematic cross-sectional view of a bottom vented secondary cell is shown in FIG.

[0089] If an event occurs inside the case 100 , it may be appropriate to discharge gas through the exhaust port 500 at the bottom thereof (eg, it may be appropriate to perform degassing). To this end, it may be appropriate to maintain a gap between the electrode assembly 200 and the exhaust port 500 to ensure a gas exhaust passage P.

[0090] In order to ensure the gas exhaust channel P, the distance between the exhaust port 500 that can be installed on the shell bottom 110 or the second cover plate 400 and the lower portion of the electrode assembly 200 (for example, the distance between the inner surface of the shell bottom 110 or the second cover plate 400 and the lower portion of the electrode assembly 200, hereinafter, referred to as the bottom gap G) may be suitable for being maintained at a certain value or greater.

[0091] The basis for the existence of the bottom gap G can be found in the following Figure 5 The relationship between the bottom space (or gap) and the internal pressure can be seen in the graph shown in FIG. In some examples, the secondary battery may be suitable for having an internal battery pressure of about 25 bar or less. Figure 5 As shown in , if the bottom gap G is about 0.7 mm or more, the internal pressure is about 25 bar or less. It may be appropriate to set the bottom gap G to about 0.7 mm or more. Considering the design margin, it may be appropriate to set the gap to about 1 mm or more, corresponding to a pressure of about 10 bar.

[0092] To ensure and maintain the bottom gap G, an injection molded part may be installed between the electrode assembly 200 and the case bottom 110 or the second cap plate 400. Since the injection molded part may be deformed or damaged by melting or burning due to heat generated in the battery, it may be difficult to maintain the ensured bottom gap G.

[0093] To solve this problem, the gap retainer can be installed in Figure 3A and Figure 3B The bottom exhaust secondary battery shown in FIG. 4 has an exhaust port 500 at its bottom, and the bottom of the secondary battery is provided with a second cap plate 400 or a housing bottom 110, thereby maintaining a gap with the electrode assembly 200 with a bottom gap G (as described above, about 0.7 mm or more, or about 1 mm or more) suitable for ensuring a gas exhaust passage. As a result, even in the event of a heat generation or during thermal runaway, the degassing performance can be improved by ensuring a gas exhaust passage.

[0094] Fig. 6A is a schematic cross-sectional view of a bottom vented secondary battery according to one or more embodiments of the present disclosure. Fig. 6A The battery shown in FIG. has the same Figure 3A The structure corresponds to the structure of the secondary battery having the housing 100 mounted with the second cap plate 400 shown in FIG.

[0095] In order to ensure the bottom gap G between the second cover plate 400 and the electrode assembly 200 in the case 100, the gap maintaining portion 420 may be formed to protrude from the inner surface of the second cover plate 400 toward the electrode assembly 200. The gap maintaining portion 420 may have a protrusion height that allows the bottom gap G between the lower portion of the electrode assembly 200 and the exhaust port 500 to be about 0.7 mm or more.

[0096] The gap maintaining part 420 may be formed on the second cover plate 400 in various ways.

[0097] In one or more embodiments, the gap retaining portion 420 may be integrally manufactured during the manufacture of the second cover plate 400. For example, if the second cover plate 400 may be manufactured by casting, the gap retaining portion 420 may be cast concurrently or substantially simultaneously by the same mold. As another example, the gap retaining portion 420 may be protruded by manufacturing the second cover plate 400 and then pressing a corresponding portion of the second cover plate 400.

[0098] In one or more other embodiments, the second cover plate 400 and the gap retaining portion 420 may be manufactured separately and then may be joined to each other. For example, after the second cover plate 400 and the gap retaining portion 420 may be manufactured separately, the gap retaining portion 420 may be joined to the second cover plate 400 by welding or any other joining technique (adhesion, riveting, bolting, etc.).

[0099] Figure 6B is a schematic cross-sectional view of a bottom exhaust secondary battery according to one or more other embodiments of the present disclosure. Figure 6B The battery shown in Figure 3B The structure of the prismatic secondary battery with the case bottom 110 shown in FIG.

[0100] In order to ensure the bottom gap G between the electrode assembly 200 and the case bottom 110, the gap maintaining portion 420 may be formed to protrude from the inner surface of the case bottom 110 toward the electrode assembly 200. Fig. 6A In one or more embodiments, the gap maintaining portion 420 may have a protrusion height that allows a bottom gap G between a lower portion of the electrode assembly 200 and the exhaust port 500 to be about 0.7 mm or more (eg, about 1 mm or more).

[0101] The gap maintaining portion 420 may be formed on the housing bottom 110 in various ways.

[0102] In one or more embodiments, the gap retaining portion 420 may be integrally manufactured during the manufacture of the housing 100. For example, during the manufacture of the housing 100, the gap retaining portion 420 may protrude by pressing or deforming a corresponding portion of the housing bottom 110.

[0103] In one or more other embodiments, the housing bottom 110 and the gap retaining portion 420 may be manufactured separately and then joined to each other. For example, after the housing 100 and the gap retaining portion 420 may be manufactured separately, the gap retaining portion 420 may be joined to the bottom 110 of the housing 100 by welding or any other joining technique (e.g., adhesion, riveting, bolting, etc.).

[0104] In some embodiments, the gap maintaining portion 420 may have various shapes such as ribs, linear protrusions, vertical walls, cylindrical or polygonal columns (or pillars), embossing, and the like.

[0105] The gap retaining portion 420 may include a plurality of gap retaining portions, in which case the separation distance between the plurality of gap retaining portions may be less than the maximum width of the electrode assembly 200. In one or more embodiments, if there are a plurality of gap retaining portions 420, the gap retaining portions 420 may be symmetrically positioned with respect to the exhaust port 500 at the center thereof.

[0106] Now, the gap maintaining portion 420 will be described in detail. 7A to 9B 4 is a plan view showing various shapes of the gap maintaining portion 420 , and may show the second cover plate 400 or the case bottom 110 in a state of being viewed from the inside of the case 100 .

[0107] The gap maintaining portion 420 may be installed to reduce or minimize interference with air flow within the case 100 while maintaining a gap (eg, a bottom gap G) between the electrode assembly 200 and the exhaust port 500 .

[0108] Fig. 7A and Figure 7B An example of a gap retaining portion 420 is shown. Around the exhaust port 500, gap retaining portions 420a, 420b, 420c, 420d, each in the form of an elongated wall or a linear protrusion in the general direction of gas flow (see the arrow direction) may be installed on the second cover plate 400 or the housing bottom 110. For example, among a pair of facing / opposite first sides (e.g., long sides 130a, 130b) and a pair of facing / opposite second sides (e.g., short sides 140a, 140b) of the second cover plate 400 or the housing bottom 110, each of the installed gap retaining portions 420a, 420b, 420c, 420d may have a length in a direction perpendicular to the second side (short sides 140a, 140b). As described above, the gap retaining portions 420a to 420d may each have a height h of about 0.7 mm or more (or about 1 mm or more).

[0109] The above configuration allows the distance from the electrode assembly 200 to be maintained without interfering with the flow path of the gas from both sides of the housing 100 toward the exhaust port 500. Here, the number of gap retaining portions is not limited to four (e.g., 420a, 420b, 420c, 420d) as shown in the drawings. In one or more embodiments, the shape of each gap retaining portion is not limited to a linear wall or protrusion as shown in the drawings. Depending on the size of the electrode assembly 200, the number and respective shapes of these gap retaining portions 420a, 420b, 420c, 420d may be appropriately changed.

[0110] Fig. 8A and Figure 8B Another example of the gap retaining portion 420 is shown. Two gap retaining portions 420e, 420f may be mounted on the second cover plate 400 or on the housing bottom 110 facing each other with respect to the exhaust port 500 therebetween. Each of the gap retaining portions 420e, 420f may be in the form of a wall or linear protrusion having a short length in the width direction of the second cover plate 400 or the housing bottom 110. For example, among a pair of facing / opposite first sides (e.g., long sides 130a, 130b) and a pair of facing / opposite second sides (e.g., short sides 140a, 140b) of the second cover plate 400 or the housing bottom 110, each of the installed gap retaining portions 420e, 420f may have a length in a direction perpendicular to the long sides 130a, 130b.

[0111] The gap retaining portions 420e, 420f may each have a length set so as not to interfere with the flow of gas (arrow direction). As described above, the gap retaining portions 420e, 420f may each have a height h of about 0.7 mm or more (or about 1 mm or more).

[0112] Here, the number of gap retaining portions is not limited to the two (e.g., 420e, 420f) shown in the drawings. In one or more embodiments, the shape of each gap retaining portion is not limited to the shape of a wall or linear protrusion as shown in the drawings. Depending on the size of the electrode assembly 200, the number and arrangement of these gap retaining portions 420e, 420f can be appropriately changed. In addition, the distance between one gap retaining portion 420e and another gap retaining portion 420f can be within the maximum range allowed by the horizontal width of the electrode assembly 200.

[0113] Fig.9A and Fig. 9B Another example of the gap holding portion 420 is shown. A plurality of gap holding portions 420g, 420h, 420i, 420j, 420k, 420l, 420m, 420n may be installed around the exhaust port 500. Here, the gap holding portions 420g, 420h, 420i, 420j, 420k, 420l, 420m, 420n may be shown as each having a substantially cylindrical column shape, but the present disclosure is not limited thereto. For example, it may have a polygonal column shape such as a square or hexagon. Here, the number of gap holding portions is not limited to eight (e.g., 420g, 420h, 420i, 420j, 420k, 420l, 420m, 420n) as shown in the drawings. According to the size of the electrode assembly 200, the respective shapes, numbers, and arrangements of these gap maintaining parts 420g, 420h, 420i, 420j, 420k, 420l, 420m, 420n may be appropriately changed.

[0114] A method of manufacturing a secondary battery having the same structure as that described above, in which the vent 500 may be installed on the second cap plate 400 or the case bottom 110 , will be described.

[0115] According to one or more embodiments of the method for manufacturing a secondary battery, an electrode assembly 200 may be manufactured, and a housing 100 in which the electrode assembly 200 is built may be manufactured, and the housing 100 may be provided with a vent 500 at its bottom. In this case, the housing 100 has a bottom 110 connected to a side thereof. A gap retaining portion 420 may be formed on the housing bottom 110 to maintain a gap between the electrode assembly 200 and the vent 500. In this case, the gap retaining portion 420 may be formed on the housing bottom 110 during or after the manufacture of the housing 100 to face the electrode assembly.

[0116] According to one or more other embodiments of the method for manufacturing a secondary battery, an electrode assembly 200 may be manufactured, and a housing 100 in which the electrode assembly 200 is built may be manufactured. In this case, the housing 100 may have an open bottom. A second cover plate 400 that may be manufactured separately may be assembled on the open bottom. The second cover plate 400 may be equipped with a vent 500 and a gap retaining portion 420.

[0117] Here, since a method of manufacturing other components and a method of forming the gap maintaining part 420 correspond to the method of manufacturing the above-described secondary battery, a description thereof will be omitted.

[0118] Hereinafter, any material that may be used for the secondary battery according to the present disclosure will be described.

[0119] As the positive electrode active material, a compound capable of reversibly inserting / deinserting lithium (eg, a lithiated inserting compound) may be used. For example, at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel or a combination thereof may be used.

[0120] The composite oxide may be a lithium transition metal composite oxide, and examples thereof may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, nickel manganese-based oxides not containing cobalt, or combinations thereof.

[0121] As an example, a compound represented by any one of the following formulae may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Lia Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NeG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0122] In the above formula: A is Ni, Co, Mn or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; and L 1 It is Mn, Al or a combination thereof.

[0123] A positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material, and may further include a binder and / or a conductive material.

[0124] The content of the positive electrode active material is in the range of about 90 wt % to about 99.5 wt % based on 100 wt % of the positive electrode active material layer, and the content of the binder and the conductive material may be in the range of about 0.5 wt % to about 5 wt % based on about 100 wt % of the positive electrode active material layer, respectively.

[0125] The current collector may be aluminum (Al), but is not limited thereto.

[0126] The negative electrode active material may include a material capable of reversibly inserting / extracting lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0127] The material capable of reversibly inserting / extracting lithium ions may be a carbon-based negative electrode active material, which may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon may include graphite such as natural graphite or artificial graphite, and examples of amorphous carbon may include soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, sintered coke, etc.

[0128] A Si-based negative electrode active material or a Sn-based negative electrode active material may be used as the material capable of doping and dedoping lithium. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Si-based alloy, or a combination thereof.

[0129] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles.

[0130] The silicon-carbon composite may also include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0131] The negative electrode for a lithium secondary battery may include a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer may include a negative electrode active material and may also include a binder and / or a conductive material.

[0132] For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0133] A non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used as the binder. If an aqueous binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may also be included.

[0134] As the negative electrode current collector, one selected from a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, and a combination thereof may be used.

[0135] The electrolyte for a lithium secondary battery may include a non-aqueous organic solvent and a lithium salt.

[0136] The non-aqueous organic solvent serves as a medium through which ions participating in the electrochemical reaction of the battery can move.

[0137] The non-aqueous organic solvent may be a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and may be used alone or in combination of two or more.

[0138] If a carbonate-based solvent is used, a mixture of a cyclic carbonate and a chain carbonate may be used.

[0139] Depending on the type of lithium secondary battery, a separator may be present between a first electrode plate (eg, a negative electrode) and a second electrode plate (eg, a positive electrode). As the separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used.

[0140] The separator may include a porous substrate and a coating on one or both surfaces of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0141] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic polymer.

[0142] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof, but is not limited thereto.

[0143] The organic material and the inorganic material may be mixed in one coating layer, or may be in the form of a coating layer containing an organic material and a coating layer containing an inorganic material stacked on each other.

[0144] Fig.10 According to one or more embodiments of the present disclosure, a prismatic secondary battery (such as Figure 3A or Figure 3B ) is a diagram of a secondary battery module. As the capacity of secondary batteries used to drive electric vehicles and the like increases, a secondary battery module can be manufactured by arranging and connecting multiple secondary battery cells laterally and / or longitudinally. Multiple secondary batteries can be arranged in a space defined by a pair of facing / opposite end plates 71a, 71b and a pair of facing / opposite side plates 72a, 72b. The secondary batteries can be appropriately designed in both arrangement (direction) and quantity to obtain desired voltage and current specifications.

[0145] Fig.11 Schematically illustrates a configuration of a battery pack according to one or more embodiments of the present disclosure. Fig.11The battery pack 80 according to one or more embodiments of the present disclosure includes an assembly to which individual batteries are electrically connected and a battery pack housing that accommodates the assembly. In the drawings, some components including bus bars, cooling units, external terminals for electrically connecting batteries, etc. are omitted for ease of illustration.

[0146] The battery pack may be mounted on (or in) a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheel vehicle or a two-wheel vehicle, but is not limited thereto.

[0147] Fig.12 The present invention is a diagram showing one or more embodiments of the present invention. Fig.11 A diagram of a vehicle with a battery pack is shown in FIG. Fig.12 , the vehicle V according to one or more embodiments of the present disclosure may include the battery pack 80 according to one or more embodiments of the present disclosure. The vehicle may be operated by receiving power from the battery pack (eg, may be powered by receiving power from the battery pack).

[0148] Although the present disclosure has been described with reference to the embodiments of the present disclosure, the present disclosure is not limited thereto. Within the spirit of the present disclosure and the equivalent scope of the appended claims and their functional equivalents to be included therein, those skilled in the art may make various modifications and changes to the embodiments.

Claims

1. A secondary battery, comprising: case; an electrode assembly in the housing; a first cover plate coupled to the housing; an exhaust port, opposite to the first cover plate; as well as The gap maintaining portion is used to maintain the gap between the electrode assembly and the exhaust port.

2. The secondary battery according to claim 1, wherein The gap maintaining portion is in the case and faces the electrode assembly.

3. The secondary battery according to claim 1, further comprising a second cover plate opposite to the first cover plate, in, The exhaust port is formed on the second cover plate, and The gap maintaining portion is on a surface of the second cover plate facing the electrode assembly.

4. The secondary battery according to claim 1, wherein A gap between the electrode assembly and the exhaust port is 0.7 mm or more.

5. The secondary battery according to claim 1, wherein The gap maintaining portion includes two or more parts.

6. The secondary battery according to claim 1, wherein The gap maintaining portion includes two or more portions located symmetrically with respect to the exhaust port.

7. The secondary battery according to claim 1, wherein The secondary battery includes a cylindrical secondary battery.

8. The secondary battery according to claim 1, wherein The secondary battery includes a prismatic secondary battery.

9. The secondary battery according to claim 1, wherein: The housing has a prismatic battery shape having a pair of opposing short sides and a pair of opposing long sides; and Wherein, the gap maintaining portion includes a linear protrusion extending in a direction perpendicular to the short side.

10. The secondary battery according to claim 1, wherein: The housing has a prismatic battery shape having a pair of opposing short sides and a pair of opposing long sides; and The gap retaining portion is a linear protrusion extending in a direction perpendicular to the long side of the housing.

11. The secondary battery according to claim 1, wherein The gap maintaining portion is a protrusion protruding toward the electrode assembly.

12. A method for manufacturing a secondary battery, the method comprising the following steps: Setting an electrode assembly; Providing a shell, the shell is used to accommodate the electrode assembly; coupling a first cover plate to the housing; forming an exhaust port at a position opposite to the first cover plate; as well as A gap maintaining portion configured to maintain a gap between the electrode assembly and the exhaust port is formed.

13. The method according to claim 12, wherein: The gap maintaining portion is at a surface of the case opposite to the first cap plate and faces the electrode assembly.

14. The method according to claim 12, further comprising installing a second cover plate in the housing opposite to the first cover plate, in, The exhaust port is on the second cover plate, and The gap maintaining portion is on a surface of the second cover plate facing the electrode assembly.

15. The method according to claim 12, wherein: The gap between the electrode assembly and the exhaust port is 0.7 mm or more.

16. The method according to claim 12, wherein: The gap maintaining portion includes two or more parts. 17 . A vehicle comprising the secondary battery according to claim 1 .

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