Bottom-vented secondary battery and method of manufacturing the same

Abstract

To provide a secondary battery including a vent through which gas may be discharged in the event of an internal event and a method of manufacturing the same, a technical issue to be solved being to provide a structure for ensuring a gas passage within a bottom-vented secondary battery with a vent at the bottom to avoid destruction of a case (can) if an event occurs or during thermal runaway due to an increase in degassing path in the secondary battery.SOLUTION: The present invention provides: a secondary battery including a case in which an electrode assembly is built and to which a first cap plate is coupled, a vent provided at a position facing the first cap plate, and a gap-maintaining part for maintaining a gap between the electrode assembly and the vent; a method of manufacturing the same; and a vehicle including the secondary battery.SELECTED DRAWING: Figure 6A

Description

[Technical field]

[0001] The present invention relates to a secondary battery and a method for manufacturing the same. [Background technology]

[0002] Unlike primary batteries, which cannot be charged, secondary batteries are batteries that can be charged and discharged. Low-capacity secondary batteries can be used in small portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and video cameras, while large-capacity secondary batteries can be widely used as motor drive power sources and power storage batteries for hybrid and electric vehicles.

[0003] In general, a secondary battery includes an electrode assembly including a positive electrode and a negative electrode, a case for accommodating the electrode assembly, electrode terminals connected to the electrode assembly, and a vent for degassing gas generated from inside the case.

[0004] The information disclosed above in this Background of the Invention section is merely intended to enhance the understanding of the background of the present invention and may thus include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to secondary batteries that include a vent through which gas can escape upon the occurrence of an internal event, and methods for manufacturing the same.

[0006] When a vent is provided at the bottom of a bottom-vented secondary battery (e.g., a so-called tall cell battery with an expanded vertical length / height), there is a problem that the case (can) may be destroyed in the event of an event or thermal runaway due to an increase in the degassing path. Therefore, we propose a structure for securing a gas flow path inside the battery to improve the degassing performance of the secondary battery.

[0007] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0008] In order to solve the above technical problems, a secondary battery according to one or more aspects of the present invention includes a case, an electrode assembly in the case, a first cap plate coupled to the case, a vent portion opposite the first cap plate, and a spacing maintaining portion for maintaining a spacing between the electrode assembly and the vent portion.

[0009] The spacing portion may be within the case and may face the electrode assembly.

[0010] The secondary battery may further include a second cap plate opposite the first cap plate, the vent portion being on the second cap plate, and the spacing portion being on a surface of the second cap plate opposite the electrode assembly.

[0011] The spacing between the electrode assembly and the vent portion may be about 0.7 mm or greater.

[0012] The spacing portion may include two or more parts.

[0013] The spacing portion may include two or more parts symmetrically disposed relative to the vent portion.

[0014] The secondary battery may include a cylindrical secondary battery.

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

[0016] The case may have a rectangular battery shape having a pair of opposing short sides and a pair of opposing long sides, and the spacing portion includes a linear protrusion extending in a direction perpendicular to the short sides.

[0017] The case may have a rectangular battery shape having a pair of opposing short sides and a pair of opposing long sides, and the spacing retaining portion is a linear protrusion extending in a direction perpendicular to the long sides of the case.

[0018] The spacing portion may be a linear protrusion extending toward the electrode assembly.

[0019] In addition, in order to solve the above technical problems, a manufacturing method for a secondary battery according to one or more other aspects of the present invention includes the steps of providing an electrode assembly, providing a case for accommodating the electrode assembly, coupling a first cap plate to the case, forming a vent portion at a position opposite to the first cap plate, and forming a spacing maintaining portion for maintaining a spacing between the electrode assembly and the vent portion.

[0020] The spacing portion may be on a surface of the case opposite the first cap plate and facing the electrode assembly.

[0021] The method includes the step of introducing a second cap plate into the case opposite the first cap plate, the vent portion being on the second cap plate and the spacing portion being on the second cap plate opposite the electrode assembly.

[0022] The spacing between the electrode assembly and the vent portion may be about 0.7 mm or greater.

[0023] The spacing portion may include two or more parts.

[0024] According to one or more other aspects of the present invention, a vehicle can be provided that includes the secondary battery / one or more secondary battery packs having the above-described configuration.

[0025] However, the present invention is not limited to the above, and other aspects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. Effect of the Invention

[0026] According to the present invention, in a bottom vent type secondary battery, particularly a cylindrical, rectangular, or coin type secondary battery with expanded horizontal to vertical length (so-called tall cell), the distance between the opposing surface of the case cap assembly (including the first cap plate) and the internal electrode assembly is kept constant (e.g., about 0.7 mm or more), thereby ensuring a gas exhaust flow path when an event occurs or thermal runaway, and improving degassing performance.

[0027] In an automobile using the secondary battery of the present invention, a vent is provided at the bottom, and even in the event of an event or thermal runaway, degassing is performed to the bottom of the automobile (e.g., the ground side), thereby ensuring the safety of passengers, and further enhancing safety by constantly ensuring a gas exhaust flow path.

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

[0029] The following drawings attached to this specification are illustrative of embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings. [Brief description of the drawings]

[0030] [Figure 1] FIG. 2 is a cross-sectional view of a cylindrical secondary battery. [Figure 2A] FIG. 2 is a top perspective view of a prismatic secondary battery. [Figure 2B]FIG. 2B is a cross-sectional view taken along line II' in FIG. 2A. [Figure 3A] FIG. 1 is a schematic diagram of a prismatic secondary battery as a bottom-vented secondary battery according to one or more embodiments of the present disclosure. [Figure 3B] FIG. 1 is a schematic diagram of a prismatic secondary battery as a bottom-vented secondary battery according to one or more other embodiments of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view of the bottom-vented prismatic secondary battery shown in FIGS. 3A and 3B. [Diagram 5] 1 is a graph showing the relationship between the internal pressure and the lower space (gap). [Figure 6A] FIG. 1 is a schematic cross-sectional view of a bottom-vented prismatic secondary battery according to one or more embodiments of the present disclosure. [Figure 6B] FIG. 1 is a schematic cross-sectional view of a bottom-vented prismatic secondary battery according to one or more embodiments of the present disclosure. [Figure 7A] FIG. 4 is a plan view showing one embodiment of a spacing portion. [Figure 7B] FIG. 13 is a perspective view showing an example of a spacing portion. [Figure 8A] FIG. 11 is a plan view showing another embodiment of the spacing portion. [Figure 8B] FIG. 13 is a perspective view showing another embodiment of the spacing portion. [Figure 9A] FIG. 13 is a plan view showing still another embodiment of the spacing portion. [Figure 9B] FIG. 13 is a perspective view showing still another embodiment of the spacing portion. [Figure 10] FIG. 2 is a diagram of a secondary battery module in which prismatic secondary batteries are arranged in accordance with one or more embodiments of the present disclosure. [Figure 11] FIG. 11 is a diagram of a secondary battery pack including the prismatic secondary battery module illustrated in FIG. 10. [Figure 12] FIG. 12 is a conceptual diagram of a vehicle including the secondary battery pack illustrated in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having a meaning and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that the inventor can appropriately define the concept of the term in order to best describe his / her invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only one or more embodiments of the present invention, and do not fully represent the technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of this application.

[0032] Additionally, as used herein, "comprise," "include," and / or "comprising," "including," specify the presence of stated features, numbers, steps, operations, members, elements, and / or groups thereof, but do not exclude the presence or addition of one or more other features, numbers, operations, members, elements, and / or groups thereof.

[0033] In addition, in order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0034] The statement that two comparison objects are "identical" means that they are "substantially identical." Therefore, "substantially identical" can include cases where there is a deviation that is considered to be a low level in the art, for example, a deviation within 5%. In addition, the uniformity of a certain parameter in a given region can mean that it is uniform from an average perspective.

[0035] Even if the terms "first", "second", etc. are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it is understood that a first component may also be a second component unless otherwise specified.

[0036] Throughout the specification, unless specifically stated to the contrary, each element may be singular or plural.

[0037] When an arbitrary structure is disposed on the "top (or bottom)" of a component or "above (or below)" a component, it can mean not only that the arbitrary structure is in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure positioned above (or below) the component.

[0038] Additionally, when a component is described as being "on," "connected to," or "coupled to" another component, it should be understood that the components may be directly coupled or connected to each other, but that there may be other components "intervening" between each component, or that each component may be "coupled," "coupled," or "connected" through other components.

[0039] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Also, when describing embodiments of the present invention, the use of "may" refers to "one or more embodiments of the present invention." Phrases such as "one or more" preceding a list of elements modify the entire list of elements and not the individual elements of the list.

[0040] Throughout the specification, when "A and / or B" is used, this means A, B, or A and B, unless otherwise specified, and when "C through D" is used, this means greater than or equal to C and less than or equal to D, unless otherwise specified.

[0041] When syntax such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group A, B, and C," or "at least one selected from among A, B, and C" is used to specify a list of elements A, B, and C, the syntax can refer to any and all suitable combinations.

[0042] The term "use" is considered synonymous with the term "utilize." As used herein, "substantially," "about," and similar terms are used as terms of approximation, not terms of degree, and are intended to account for inherent variations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art.

[0043] In this specification, terms such as first, second, third, etc. are used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. The terms are used to distinguish one element, component, region, drawing layer, or section from another element, component, region, drawing layer, or section. Thus, a first element, component, region, level, or section discussed below may be named a second element, component, region, level, or section without departing from the teachings of the exemplary embodiments.

[0044] In describing the relationship of an element or feature to another element or feature as shown, for ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like are used in the specification. Spatially relative positions will be understood to encompass different orientations of the device in use or operation other than the orientation depicted in the figures. For example, if the device in the figures is turned over, the other elements will be understood as "below" or "below" and the illustrated element as "above" or "upper" of the other elements. Thus, the term "below" can encompass both an orientation of above and below.

[0045] The terminology used herein is for the purpose of describing embodiments of the present invention and is not intended to be limiting of the present invention.

[0046] Secondary batteries are classified into coin type, cylindrical type, prismatic type, and pouch type. Since the present invention is basically applicable to cylindrical and prismatic secondary batteries, cylindrical and prismatic secondary batteries will be briefly described first before describing the embodiments of the present invention.

[0047] 1 is a cross-sectional view of a cylindrical secondary battery. The cylindrical secondary battery includes an electrode assembly 30, a case 10 that contains the electrode assembly 30 and an electrolyte, a cap assembly 50 that is coupled to an opening of the case 10 to seal the case 10, and an insulating plate 37 that is located inside the case 10 between the electrode assembly 30 and the cap assembly 50.

[0048] The electrode assembly 30 may include a first electrode 33 and a second electrode 31 with a separator 32 therebetween, wound into a jelly-roll.

[0049] The first electrode 33 may include a first substrate and a first active material layer disposed on the first substrate. A first lead tab 35 may extend outward from a first uncoated portion of the first substrate where the first active material layer is not disposed. The first lead tab 35 may be electrically connected to the cap assembly 50.

[0050] The second electrode 31 may include a second substrate and a second active material layer located on the second substrate. A 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 case 10. The first lead tab 35 and the second lead tab 34 may extend in opposite directions to each other.

[0051] The first electrode 33 can function as a positive electrode. In this case, the first substrate can be made of, for example, aluminum foil, and the first active material layer can include, for example, a transition metal oxide. The second electrode 31 can function as a negative electrode. In this case, the second substrate can be made of, for example, copper foil or nickel foil, and the second active material layer can include, for example, graphite.

[0052] The separator 32 functions to allow the movement of lithium ions while reducing or preventing the possibility of a short circuit between the first electrode 33 and the second electrode 31. The separator 32 is made of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, or the like.

[0053] The case 10 contains the electrode assembly 30 and an electrolyte, and together with the cap assembly 50, defines the outer shape of the battery. The case 10 may include a substantially cylindrical body portion 12 and a bottom portion 11 connected to one side of the body portion 12. A beading portion 13 deformed inward is located in the body portion 12, and a crimping portion 15 bent inward may be located at an end of the opening side of the body portion 12.

[0054] The beading portion 13 can prevent the electrode assembly 30 from moving inside the case 10 and can facilitate placement of the gasket 14 and the cap assembly 50. The crimping portion 15 can apply pressure to the periphery of the cap assembly 50 via the gasket 14 to firmly fix the cap assembly 50. The case 10 includes, for example, nickel-plated iron.

[0055] The cap assembly 50 is fixed to the inside of the crimping portion 15 via the gasket 14 to seal the case 10. The cap assembly 50 may include a cap-up, a safety vent, a cap-down, an insulating member, and a sub-plate, but the cap assembly is not limited to this example and may be modified in various ways.

[0056] The cap up may be located on the top side of the cap assembly 50. The cap up may include a terminal portion that bulges upward and protrudes to be connected to an external circuit, and an exhaust port for exhausting gas may be located around the terminal portion.

[0057] The safety vent may be located under the cap-up. The safety vent may include a protrusion that bulges downward and protrudes to be connected to the subplate, and at least one notch located around the protrusion.

[0058] When gas is generated due to overcharging or abnormal operation of the secondary battery, the protrusion is deformed upward by pressure and separated from the sub-plate, while the safety vent is cut along the notch. The cut safety vent can release gas to the outside to reduce or prevent the possibility of an explosion of the secondary battery.

[0059] The cap down may be located below the safety vent. The cap down may have a first opening for exposing the protruding portion of the safety vent and a second opening for discharging gas. The insulating member may be located between the safety vent and the cap down to insulate the safety vent from the cap down.

[0060] The subplate may be located below the cap down. The subplate is fixed to the underside of the cap down so as to cover the first opening of the cap down. A protruding portion of the safety vent is fixed to the subplate. A first lead tab 35 that can be led out of the electrode assembly 30 is fixed to the subplate. In one or more embodiments, the cap up, the safety vent, the cap down, and the subplate can be electrically coupled to the first electrode 33 of the electrode assembly 30.

[0061] The insulating plate 37 may be positioned so as to contact the electrode assembly 30 below the beading portion 13, and the insulating plate 37 is provided with a tab opening for drawing out the first lead tab 35. The cap assembly 50 electrically connected to the first electrode 33 by the first lead tab 35 may face the electrode assembly 30 with the insulating plate 37 in between. The cap assembly 50 can maintain an insulated state from the electrode assembly 30 by the insulating plate 37. In one or more embodiments, another insulating plate 36 is included for insulation between the electrode assembly 30 and the bottom 11 of the case 10.

[0062] FIG. 2A is a top perspective view of a prismatic secondary battery, and FIG. 2B is a cross-sectional view taken along line II' in FIG. 2A.

[0063] First, the external appearance of the prismatic secondary battery shown in FIG. 2A will be described.

[0064] The case 51 forms the overall appearance of the prismatic secondary battery and is made of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. In one or more embodiments, the case 51 can provide a space in which an electrode assembly is housed.

[0065] The cap assembly 60 may include a cap plate 61 that covers the opening of the case 51, and the cap assembly 60 and the cap plate 61 are made of a conductive material. Here, the first terminal 62 and the second terminal 63 are electrically connected to the internal positive electrode or negative electrode and are provided to penetrate the cap plate 61 and protrude outward.

[0066] The cap plate 61 is formed with an electrolyte injection hole 64 for providing a sealing plug, and is also provided with a vent 66 having a notch 65. The vent 66 can degass gas generated from inside the battery.

[0067] The internal structure of the prismatic secondary battery and the connection structure with the cap assembly 60 will be described with reference to FIG. 2B.

[0068] The prismatic secondary battery shown in FIG. 2B can basically include an electrode assembly 40, a first current collecting portion 41, a first terminal 62, a second current collecting portion 42, a second terminal 63, and a cap assembly 60.

[0069] The electrode assembly 40 is formed by winding or stacking a laminate of a first electrode plate, a separator, and a second electrode plate, which are formed in a plate or film shape. When the electrode assembly 40 is a wound laminate, the winding axis may be parallel to the longitudinal direction of the case. The electrode assembly 40 may also be a stack type that is not a winding type, but this does not limit the shape of the electrode assembly 40 in the present invention. In one or more embodiments, the electrode assembly 40 may be a Z-stack electrode assembly in which the first electrode plate and the second electrode plate are inserted on both sides of the separator folded into a Z-stack. In one or more embodiments, the electrode assembly 40 may be one or more electrode assemblies stacked with their long sides adjacent to each other and housed inside the case, and this does not limit the number of electrode assemblies in the present invention. The first electrode plate of the electrode assembly 40 can serve as a negative electrode, and the second electrode plate can serve as a positive electrode. In one or more embodiments, the reverse is also possible.

[0070] The first electrode plate is formed by applying a first electrode active material such as graphite or carbon to a first electrode current collector plate formed of a metal foil such as copper, copper alloy, nickel, or nickel alloy, and may include a first electrode tab (or a first uncoated portion) which is a region where the first electrode active material is not applied. The first electrode tab 43 serves as a current path between the first electrode plate and the first current collector 41. In some examples, the first electrode tab 43 may be formed by cutting in advance to protrude from one side when manufacturing the first electrode plate, or may protrude further from one side beyond the separator without a separate cut.

[0071] The second electrode plate is formed by applying a second electrode active material, such as a transition metal oxide, to a substrate formed of a metal foil such as aluminum or an aluminum alloy, and may include a second electrode tab (or a second uncoated portion) 44, which is an area to which the second electrode active material is not applied. The second electrode tab 44 serves as a current path between the second electrode plate and the second current collector 42. In some examples, the second electrode tab 44 may be formed by cutting in advance to protrude to the other side when manufacturing the second electrode plate, or may protrude further to the other side beyond the separator without a separate cut.

[0072] In some embodiments, the first electrode tab 43 may be located on a side surface at the right end of the electrode assembly 40, and the second electrode tab 44 may be located on a side surface at the left end of the electrode assembly 40, or may be located on one surface in the same direction. Also, in some embodiments, the first electrode tab 43 and the second electrode tab 44 may be located on the top of the electrode assembly 40.

[0073] Here, the left side, right side, and top are for convenience of explanation based on the secondary battery shown in FIG. 2A, and the positions can be changed if the secondary battery is rotated left / right or up / down.

[0074] The separator functions to reduce or prevent the possibility of short circuit between the first electrode plate and the second electrode plate while allowing the movement of lithium ions. The separator is made of, for example, a polyethylene film, a polypropylene film, a polyethylene-polypropylene film, or the like.

[0075] A first electrode tab 43 of the first electrode plate and a second electrode tab 44 of the second electrode plate extend from both ends of the electrode assembly 40. In some embodiments, the electrode assembly 40 is housed in a case 51 together with an electrolyte.

[0076] In the electrode assembly 40, a first electrode tab 43 and a second electrode tab 44 extending from both sides of the first electrode plate and the second electrode plate can be connected to the first current collecting part 41 and the second current collecting part 42 by welding, respectively. If, as mentioned above, the first electrode tab 43 and the second electrode tab 44 are located at the top of the electrode assembly 40 in some embodiments, the first current collecting part 41 and the second current collecting part 42 will be located at the top of the electrode assembly 40.

[0077] The first current collecting part 41 and the second current collecting part 42 are respectively connected to the first terminal 62 and the second terminal 63 described in Fig. 2A via a connecting pole 67. In some embodiments, the outer circumferential surface of the connecting pole 67 may be threaded and may be fastened to the first terminal 62 and the second terminal 63 (e.g., by screws, riveting, or welding).

[0078] In the cylindrical and prismatic secondary batteries of the configurations described with reference to FIGS. 1, 2A, and 2B, the vent portions for gas release are shown to be provided in the cap assemblies 50 and 60, but in one or more other embodiments, the vent portions may be provided in a position facing / opposite the cap assemblies 50 and 60.

[0079] For ease of understanding, hereinafter, a certain position of the cap assembly 50 and / or 60 will be referred to as the "upper portion", and conversely, a position facing / opposite the cap assembly 50 and / or 60 will be referred to as the "lower portion".

[0080] As described above, the vent portion provided at the position facing / opposite the cap assembly 50 and / or 60 can vent gas to the bottom of the vehicle (e.g., to the ground side) (e.g., when used for a hybrid or electric vehicle), thereby ensuring safety for passengers and the environment. In this specification, a secondary battery having a vent portion provided at the bottom is referred to as a "bottom vent type secondary battery." Such a bottom vent type secondary battery can be applied to a secondary battery with an expanded horizontal to vertical length (so-called tall cell), but is not limited thereto.

[0081] Hereinafter, an embodiment of the bottom vent type secondary battery according to the present invention will be described.

[0082] 3A is a schematic diagram of a prismatic secondary battery according to one or more embodiments of a bottom vent type secondary battery having a vent portion at the bottom. The illustrated prismatic secondary battery may have a structure (e.g., a tall cell) that is longer in length than the prismatic secondary battery of FIG. 2A, but is not limited thereto.

[0083] A jelly-roll or stack-shaped electrode assembly 200 is housed inside the case 100, and a cap assembly 300 is located in an open portion at the top of the case 100. The cap assembly 300 includes a first cap plate 310, a first terminal 320a, and a second terminal 320b.

[0084] 3A (and 3B), the first electrode tab 210 and the second electrode tab 220 are shown positioned on the upper surface of the electrode assembly 200 inside the case 100, but this is merely a conceptual illustration of one example, and the present invention and the following embodiments are not limited thereto. For example, there may also be a secondary battery with a so-called side tab structure in which electrode tabs are positioned on both sides.

[0085] A second cap plate 400 is provided at an opening at the bottom of the case 100 (e.g., a position facing or opposite the cap assembly 300 or first cap plate 310 mentioned above). A gas exhaust hole 410 is formed in the second cap plate 400. A vent portion 500 configured to burst due to gas inside the case 100 is attached to the gas exhaust hole 410 by welding or the like.

[0086] Meanwhile, FIG. 3B is a schematic diagram of a prismatic secondary battery according to one or more other embodiments of a bottom vent type secondary battery in which a vent portion is provided at the bottom.

[0087] As in one or more embodiments of Fig. 3A, an electrode assembly 200 is built into the case 100, and a cap assembly 300 is provided in an open portion at the top of the case 100. In one or more embodiments, in the case 100 of one or more embodiments of Fig. 3B, unlike the case of Fig. 3A, the lower portion of the case 100 is connected to a side portion to form a bottom portion 110 that is closed at the lower portion.

[0088] A gas exhaust hole 120 is formed in the case bottom 110, and a vent portion 500 configured to burst due to the gas inside the case 100 is attached to the gas exhaust hole 120 by welding or the like.

[0089] The cap assembly 300 includes a first cap plate 310, a first terminal 320a, and a second terminal 320b, with the first electrode tab 210 and the second electrode tab 220 located on the upper surface of the electrode assembly 200, similar to one or more embodiments of FIG. 3A.

[0090] As described above, in the bottom vent type secondary battery illustrated in Figures 3A and 3B, the number of degassing paths increases (when the battery has a tall cell structure with an expanded vertical length), and the case (can) may burst during an event or thermal runaway. Therefore, it may be appropriate to secure a gas exhaust path to improve the degassing performance.

[0091] The suitability of the gas exhaust flow path to be secured will be described with reference to Fig. 4. Fig. 4 is a schematic cross-sectional view of the bottom vent type prismatic secondary battery shown in Figs. 3A and 3B.

[0092] In the event of an event occurring inside the case 100, gas can be suitably exhausted (e.g., degassing can be suitably performed) through the vent portion 500 at the bottom, and for this purpose, it may be appropriate to maintain a gap between the electrode assembly 200 and the vent portion 500 to ensure a gas exhaust flow path P.

[0093] In order to ensure a gas exhaust flow path P, the distance between the vent portion 500, which may be provided in the case bottom 110 or the second cap plate 400, and the lower portion of the internal electrode assembly 200 (for example, the distance between the inner surface of the case bottom 110 or the second cap plate 400 and the lower portion of the electrode assembly 200 (hereinafter, the lower gap G)) can be suitably maintained at a certain value or greater.

[0094] The existence of the lower gap G is based on a graph of the relationship between the lower space (gap) and the internal pressure shown in Fig. 5. In some examples, the internal pressure of a secondary battery cell may be preferably 25 bar or less, but when the lower gap G is about 0.7 mm or more, the internal pressure becomes about 25 bar or less, as shown in Fig. 5. It may be appropriate to set the lower gap G to at least about 0.7 mm or more, and considering a design margin, it may be appropriate to set the lower gap G to a gap of about 1 mm or more, which corresponds to a pressure of about 10 bar.

[0095] In order to secure and maintain the lower gap G, an injection material may be provided between the electrode assembly 200 and the case bottom 110 or the second cap plate 400. The injection material may melt or burn and be deformed or destroyed due to internal heat generation in the cell, making it difficult to maintain the secured lower gap G.

[0096] To solve this problem, a spacing retainer is provided on the second cap plate 400 or case bottom 110 of the bottom vent type prismatic secondary battery shown in Fig. 3A or 3B, which has a vent portion 500 at the bottom, to maintain the spacing with the internal electrode assembly 200 as a lower gap G suitable for securing a gas exhaust flow path (about 0.7 mm or more, or about 1 mm or more, as mentioned above). This ensures a gas exhaust flow path even in the event of an event such as heat generation or thermal runaway, and improves degassing performance.

[0097] 6A is a schematic cross-sectional view of a bottom-vented prismatic secondary battery according to one or more embodiments of the present invention. The battery structure shown in FIG 6A corresponds to the secondary battery having case 100 with second cap plate 400 shown in FIG 3A.

[0098] In order to secure a lower gap G between the electrode assembly 200 and the second cap plate 400 inside the case 100, a spacing retaining portion 420 is provided on the inner surface of the second cap plate 400 to protrude toward the electrode assembly 200. The protruding height of the spacing retaining portion 420 is set so that the lower gap G between the lower portion of the electrode assembly 200 and the vent portion 500 is about 0.7 mm or more.

[0099] The spacing portion 420 of the second cap plate 400 may be formed in various ways.

[0100] In one or more embodiments, the spacing portion 420 can be fabricated integrally with the second cap plate 400 when the second cap plate 400 is fabricated. For example, if the second cap plate 400 is fabricated using a casting, the spacing portion 420 can be cast together or substantially simultaneously in the same mold. As another example, after the second cap plate 400 is fabricated, the spacing portion 420 can be pressed in place to protrude the spacing portion 420.

[0101] In one or more other embodiments, the second cap plate 400 and the spacing member 420 can be fabricated separately and then bonded together. For example, the second cap plate 400 can be fabricated, the spacing member 420 can be fabricated separately, and then the spacing member 420 can be bonded to the second cap plate 400 by welding or other bonding techniques (such as gluing, riveting, bolting, etc.).

[0102] 6B is a schematic cross-sectional view of a bottom vented prismatic secondary battery according to one or more other embodiments of the present invention. The battery structure shown in FIG. 6B corresponds to the prismatic secondary battery having spacer 420 on case bottom 110 shown in FIG. 3B.

[0103] In order to ensure a lower gap G between the electrode assembly 200 and the case bottom 110, a spacing portion 420 is formed on the inner surface of the case bottom 110 so as to protrude toward the electrode assembly 200. The protruding height of the spacing portion 420 is such that the lower gap G between the lower portion of the electrode assembly 200 and the vent portion 500 is about 0.7 mm or more (e.g., about 1 mm or more), as in one or more embodiments of FIG.

[0104] The spacing portion 420 may be formed on the case bottom 110 in various ways.

[0105] In one or more embodiments, the spacing portion 420 can be fabricated integrally with the second cap plate 400 during fabrication. For example, the bottom portion 110 can be pressed or deformed at that location during fabrication of the case 100 to cause the spacing portion 420 to protrude.

[0106] In one or more other embodiments, case bottom 110 and spacing portion 420 can be fabricated separately and then joined together. For example, case 100 can be fabricated, spacing portion 420 can be fabricated separately, and spacing portion 420 can then be welded or otherwise joined (such as by gluing, riveting, bolting, etc.) to bottom 110 of case 100.

[0107] In some embodiments, the shape of the spacing portion 420 may be various shapes such as a rib, a linear protrusion, a vertical wall, a cylindrical or polygonal pillar, a column, an embossing, and the like.

[0108] The spacing portion 420 may include a plurality of spacing portions, and in this case, a distance between the plurality of spacing portions may be less than a maximum width of the electrode assembly 200. In one or more embodiments, when the spacing portion 420 is multiple, each spacing portion 420 may be symmetrically positioned with the vent portion 500 at the center.

[0109] 7A to 9B are plan views illustrating various shapes of the spacing portion 420, and may show the second cap plate 400 or the case bottom 110 as viewed from inside the case 100.

[0110] The spacing portion 420 may be provided in a shape that reduces or minimizes the obstruction of gas flow within the case 100 while maintaining the distance (e.g., lower gap G) between the electrode assembly 200 and the vent portion 500.

[0111] 7A and 7B show an example of the spacing portion 420. Around the vent portion 500, the second cap plate 400 or the case bottom 110 is provided with spacing portions 420a, 420b, 420c, and 420d in the form of a wall or linear protrusion extending long along the overall gas flow direction (arrow). For example, the spacing portions 420a, 420b, 420c, and 420d are provided between a pair of opposing / opposite first sides (e.g., long sides 130a, 130b) of the second cap plate 400 or the case bottom 110 and a pair of opposing / opposite second sides (e.g., short sides 140a, 140b) of the other pair of opposing / opposite second sides, each having a length perpendicular to the second side (short side 140a, 140b). The height h of each of the spacing portions 420a, 420b, 420c, and 420d is, as mentioned above, about 0.7 mm or greater, or about 1 mm or greater.

[0112] The above configuration allows the electrode assembly 200 to be spaced apart without impeding the gas flow path from both sides of the case 100 toward the vent portion 500. Here, the number of spacing portions is not limited to the four shown (e.g., 420a, 420b, 420c, and 420d). In one or more embodiments, the shapes are also not limited to the linear walls or protrusions shown. The number and shapes of the spacing portions 420a, 420b, 420c, and 420d can be changed as appropriate depending on the size of the electrode assembly 200.

[0113] 8A and 8B show another embodiment of the spacing portion 420. Two spacing portions 420e, 420f are provided on the second cap plate 400 or the case bottom 110 so as to face each other with the vent portion 500 therebetween. These spacing portions 420e, 420f are in the form of a wall or linear protrusion having a short length in the width direction of the second cap plate 400 or the case bottom 110. For example, the spacing portions 420e, 420f are provided on a pair of opposing / opposite first sides (e.g., long sides 130a, 130b) of the second cap plate 400 or the case bottom 110 and a pair of opposing / opposite second sides (e.g., short sides 140a, 140b) of the second cap plate 400 or the case bottom 110, and have a length perpendicular to the long sides 130a, 130b.

[0114] The length of the spacing portions 420e, 420f is set so as not to be impeded by the gas flow (arrows). The height h of each spacing portion 420e, 420f is, as mentioned above, about 0.7 mm or more, or about 1 mm or more.

[0115] Here, the number of the spacing portions 420e, 420f is not limited to two. In one or more embodiments, the shape is not limited to the illustrated wall or linear protrusion shape. The number and arrangement of the spacing portions 420e, 420f can be changed as appropriate depending on the size of the electrode assembly 200. Furthermore, the separation distance between the spacing portion 420e and another spacing portion 420f may be within the maximum range allowed by the width of the electrode assembly 200.

[0116] 9A and 9B show yet another embodiment of the spacing portion 420. A plurality of spacing portions 420g, 420h, 420i, 420j, 420k, 420l, 420m, and 420n are provided around the vent portion 500. The spacing portions 420g, 420h, 420i, 420j, 420k, 420l, 420m, and 420n are shown in a substantially cylindrical columnar shape, but are not limited thereto. For example, they may be polygonal columns such as squares or hexagons. Also, the number of spacing portions is not limited to eight as shown (for example, 420g, 420h, 420i, 420j, 420k, 420l, 420m, and 420n). Depending on the size of the electrode assembly 200, the individual shapes, the number and the arrangement of these spacing portions 420g, 420h, 420i, 420j, 420k, 420l, 420m and 420n can be changed as appropriate.

[0117] A method for manufacturing a secondary battery having the vent portion 500 provided in the second cap plate 400 or the case bottom portion 110 having the above-mentioned structure will be described.

[0118] According to one or more embodiments of the method for manufacturing a secondary battery, an electrode assembly 200 is prepared, a case 100 in which the electrode assembly 200 is incorporated is prepared, and a vent portion 500 is provided at the bottom. At this time, the case 100 has a bottom 110 connected to a side surface. A spacing portion 420 for maintaining a spacing between the electrode assembly 200 and the vent portion 500 is formed at the case bottom 110. At this time, the spacing portion 420 may be formed at the case bottom 110 to face the electrode assembly during or after the step of preparing the case 100.

[0119] According to one or more other embodiments of the method for manufacturing a secondary battery, an electrode assembly 200 is prepared, and then a case 100 in which the electrode assembly 200 is housed is prepared. At this time, the case 100 has an open bottom. A separately prepared second cap plate 400 is assembled to the open bottom. The second cap plate 400 is provided with a vent portion 500 and a spacing portion 420.

[0120] Here, the manufacturing methods of the other elements and the forming method of the spacer 420 correspond to the structure of the secondary battery described above, and therefore the description thereof will be omitted.

[0121] Materials that can be used in the secondary battery according to the present invention will now be described.

[0122] The positive electrode active material may be a compound capable of reversibly inserting and extracting lithium (lithiated insertion compound). Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, or a combination thereof may be used.

[0123] The composite oxide may be a lithium transition metal composite oxide, and specific examples include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel-manganese-based oxides, or combinations thereof.

[0124] As an example, a compound represented by any one of the following chemical formulas can be used. 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);Li a 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 NiG 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 Mn2G 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);Li a FePO4(0.90≦a≦1.8).

[0125] 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; L 1 is Mn, Al, or a combination thereof.

[0126] The 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 includes a positive electrode active material, and may further include a binder and / or a conductive material.

[0127] The content of the positive electrode active material is 90% by weight to 99.5% by weight based on about 100% by weight of the positive electrode active material layer, and the contents of the binder and the conductive material may each be 0.5% by weight to 5% by weight based on about 100% by weight of the positive electrode active material layer.

[0128] Al can be used as the current collector, but is not limited thereto.

[0129] The negative electrode active material includes a material capable of reversibly inserting / desorbing lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping with lithium, or a transition metal oxide.

[0130] Examples of the material capable of reversibly inserting / desorbing lithium ions include, as a carbon-based negative electrode active material, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon, hard carbon, mesophase pitch carbide, fired coke, and the like.

[0131] As the material capable of doping and dedoping with lithium, an Si-based negative electrode active material or an Sn-based negative electrode active material can be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), an Si-based alloy, or a combination thereof.

[0132] 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 a form in which amorphous carbon is coated on the surface of silicon particles.

[0133] The silicon-carbon composite may further contain crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles, and an amorphous carbon coating layer located on the surface of the core.

[0134] The negative electrode for a lithium secondary battery includes a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer includes a negative electrode active material, and may further include a binder and / or a conductive material.

[0135] For example, the negative electrode active material layer can contain 90% to 99% by weight of the negative electrode active material, 0.5% to 5% by weight of the binder, and 0% to 5% by weight of the conductive material.

[0136] The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof. When an aqueous binder is used as the negative electrode binder, the negative electrode binder may further include a cellulose-based compound capable of imparting viscosity.

[0137] The negative electrode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0138] The electrolyte for the lithium secondary battery includes a non-aqueous organic solvent and a lithium salt.

[0139] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0140] The non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof, and may be used alone or in combination of two or more kinds.

[0141] When a carbonate-based solvent is used, a mixture of a cyclic carbonate and a chain carbonate can be used.

[0142] Depending on the type of lithium secondary battery, a separator may be present between the positive electrode and the negative electrode. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers of these can be used.

[0143] The separator may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0144] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0145] The inorganic material may include, but is not limited to, 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.

[0146] The organic material and the inorganic material may be mixed in one coating layer, or may be in the form of a laminate of a coating layer containing an organic material and a coating layer containing an inorganic material.

[0147] Fig. 10 is a diagram of a secondary battery module in which rectangular secondary batteries according to one or more embodiments of the present invention shown in Fig. 3A or 3B are arranged. Due to the need for high-capacity secondary batteries for driving electric vehicles and the like, a secondary battery module is fabricated by arranging and connecting multiple secondary battery cells in a horizontal and / or vertical direction.

[0148] A plurality of secondary batteries are arranged in a space defined by a pair of opposing end plates 71 a, 71 b and a pair of opposing side plates 72 a, 72 b. The arrangement of the secondary batteries can be designed in terms of both the arrangement direction and the number of batteries to obtain the desired voltage and current specifications.

[0149] FIG. 11 is a diagram illustrating a secondary battery pack 80 configured for applying the prismatic secondary battery module illustrated in FIG. 10 to an actual product (for example, an automobile).

[0150] A secondary battery pack can be manufactured by incorporating a plurality of secondary battery modules into a pack housing designed to be mounted in an actual product. The pack housing includes fastening parts and electrical leads required for mounting to the product. For convenience of illustration, FIG. 11 does not show related elements such as a bus bar for electrically connecting the secondary batteries, a cooling unit, and external terminals.

[0151] The secondary battery pack can be installed in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheel drive or two-wheel drive vehicle.

[0152] Fig. 12 is a diagram for explaining an automobile according to one or more embodiments including the secondary battery pack illustrated in Fig. 11. Fig. 12 illustrates that a secondary battery pack 80 according to one or more embodiments of the present invention is mounted on the lower part of a body of an automobile V. The automobile V operates by receiving power supply from the secondary battery pack 80 according to one or more embodiments of the present invention.

[0153] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims described below, and it goes without saying that functional equivalents thereof are included therein. [Explanation of symbols]

[0154] 10: case, 11: bottom, 12: body, 13: beading, 14: gasket, 15: crimping, 30: electrode assembly, 31: second electrode, 32: separator, 33: first electrode, 34: second lead tab, 35: first lead tab, 36: insulating plate, 37: insulating plate, 40: electrode assembly, 41: first current collector, 42: second current collector, 43: first electrode tab, 44: second electrode tab, 50: cap assembly, 51: case, 60: cap assembly, 61: cap plate, 62: first terminal, 63: second terminal, 64: electrolyte injection port, 65: notch, 66: vent, 67: connecting column, 71a, 71 b: end plate, 72a, 72b: side plates, 80: secondary battery pack, 100: case, 110: case bottom, 120: gas exhaust hole, 130a, 130b: long sides, 140a, 140b: short sides, 200: electrode assembly, 210: first electrode tab, 220: second electrode tab, 300: cap assembly, 310: first cap plate, 320a: first terminal, 320b: second terminal, 400: second cap plate, 410: gas exhaust hole, 420: spacing portion, 420a to 420n: spacing portions, 500: vent portion, G: lower gap, h: height of spacing portion, P: gas exhaust flow path, V: automobile

Claims

1. Case and an electrode assembly in the case; a first cap plate coupled to the case; a vent portion facing the first cap plate; a spacer for maintaining a space between the electrode assembly and the vent portion.

2. The secondary battery according to claim 1 , wherein the spacing portion is located within the case and faces the electrode assembly.

3. a second cap plate facing the first cap plate; the vent portion is on the second cap plate; The secondary battery of claim 1 , wherein the spacing portion is provided on a surface of the second cap plate facing the electrode assembly.

4. The secondary battery according to claim 1 , wherein the gap between the electrode assembly and the vent portion is maintained at about 0.7 mm or more.

5. The secondary battery of claim 1 , wherein the spacing portion includes two or more parts.

6. The secondary battery of claim 1 , wherein the spacing portion includes two or more parts symmetrically positioned about the vent portion.

7. The secondary battery of claim 1 , wherein the secondary battery comprises a cylindrical secondary battery.

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

9. the case is rectangular having a pair of opposing short sides and a pair of opposing long sides, The secondary battery according to claim 1 , wherein the spacing portion includes a linear protrusion extending perpendicular to the short side.

10. the case is rectangular having a pair of opposing short sides and a pair of opposing long sides, The secondary battery according to claim 1 , wherein the spacing portion is a linear protrusion extending perpendicular to the long side.

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

12. Providing an electrode assembly; providing a case for housing the electrode assembly; coupling a first cap plate to the case; forming a vent portion at a position opposite the first cap plate; forming a spacer that maintains a space between the electrode assembly and the vent portion.

13. The method of claim 12 , wherein the spacing portion is on a surface of the case facing the first cap plate and faces the electrode assembly.

14. and additionally including the step of placing a second cap plate within the case opposite the first cap plate; The method of claim 12 , wherein the vent portion is on the second cap plate, and the spacing portion is located on a surface of the second cap plate facing the electrode assembly.

15. The method of claim 12, wherein a distance between the electrode assembly and the vent is about 0.7 mm or more.

16. The method for manufacturing a secondary battery according to claim 12 , wherein the spacing portion includes two or more components.

17. An automobile comprising the secondary battery according to claim 1.

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