Secondary battery

Abstract

A secondary battery includes: an electrode assembly including a first electrode plate having a first electrode tab, a second electrode plate having a second electrode tab, and a separator between the first electrode plate and the second electrode plate; and a case accommodating the electrode assembly. The separator includes an extension portion extending in a direction in which gas is discharged to the outside of the case.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0177605 filed in the Korean Intellectual Property Office on December 17, 2020, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] Aspects of embodiments of the present disclosure relate to an electrode assembly and a secondary battery having the same. Background Art

[0004] The secondary battery includes an electrode assembly having a positive electrode plate, a negative electrode plate, and a separator that are sequentially wound or stacked, and the electrode assembly and an electrolyte solution or a solid electrolyte are accommodated in a case.

[0005] According to the shape of the shell, secondary batteries can be divided into circular (or cylindrical) batteries, prismatic batteries, pouch batteries, etc. As an example, a prismatic battery is configured so that a wound or stacked electrode assembly is accommodated in a hexahedral shell, and a cap assembly is pressed to protrude to one side of the positive electrode substrate and the negative electrode substrate, and then assembled. Therefore, the size of the separator is limited in the direction in which the positive electrode substrate and the negative electrode substrate protrude.

[0006] However, when the prismatic battery is exposed to heat, internal heat may accumulate toward (or near) the cap assembly, which may cause damage to the separator disposed on the upper side. In this case, the separator may shrink or melt to cause a short circuit.

[0007] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0008] Embodiments of the present disclosure provide an electrode assembly having a structure for preventing an internal short circuit and a secondary battery having the same.

[0009] These and other aspects and features of the present disclosure will be described in or will be apparent from the following description of embodiments of the present disclosure.

[0010] A secondary battery according to an embodiment of the present disclosure includes: an electrode assembly including a first electrode plate having a first electrode terminal tab, a second electrode plate having a second electrode terminal tab, and a separator between the first electrode plate and the second electrode plate; and a housing accommodating the electrode assembly. The separator includes an extension portion extending in a direction in which gas is discharged to the outside of the housing.

[0011] The secondary battery may further include a cap assembly coupled to the opening in the case. A width of the extending portion may be smaller than a gap between the cap assembly and the electrode assembly.

[0012] One end of the extending portion facing the cap assembly may be closer to the cap assembly than to the electrode assembly.

[0013] The cap assembly may include a safety vent, and the extension may be adjacent to the safety vent.

[0014] A width of the extension portion may be smaller than a width of the electrode assembly.

[0015] The width of the extension portion may be smaller than a width of the electrode assembly and greater than a width of the first electrode tab or the second electrode tab.

[0016] The length of the extending portion may be smaller than a distance between the first electrode tab and the second electrode tab.

[0017] An edge of the extending portion may have an arc shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a perspective view showing a secondary battery according to an embodiment of the present disclosure.

[0019] Figure 2 It is shown Figure 1 A side view showing the shape of an electrode assembly in a secondary battery.

[0020] Figure 3 It is shown Figure 1 Schematic diagram of the assembled state of the cap assembly in the secondary battery shown.

[0021] Figure 4 is a schematic diagram showing an electrode assembly to which a separator according to an embodiment of the present disclosure is applied.

[0022] Figure 5 It is shown Figure 4 A plan view of the partition is shown in the deployed state.

[0023] Figure 6 is a schematic diagram showing an electrode assembly to which a separator according to an embodiment of the present disclosure is applied.

[0024] Figure 7 is a schematic diagram showing an electrode assembly to which a separator according to an embodiment of the present disclosure is applied. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present disclosure will be described in detail. However, the subject matter of the present disclosure can be embodied in many different forms and should not be understood as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure thorough and complete and to convey the aspects and features of the present disclosure to those skilled in the art.

[0026] In the accompanying drawings, the size or thickness of various components may be exaggerated for simplicity and clarity. The same number always refers to the same element. As used herein, the term "and / or" includes any and all combinations of one or more related listed items. In addition, it will be understood that when element A is referred to as being "connected to" element B, element A may be directly connected to element B, or there may be an intermediate element C therebetween so that element A and element B are indirectly connected to each other.

[0027] Further, when describing embodiments of the present disclosure, the use of “may” refers to “one or more embodiments of the present disclosure.” When preceding a list of elements, expressions such as “at least one of,” modify the entire list of elements rather than the individual elements in the list. As used herein, the terms “use” and “used” may be considered synonymous with the terms “utilizing” and “utilized,” respectively. As used herein, the terms “substantially,” “approximately,” and similar terms are used as terms of approximation rather than terms of degree, and are intended to take into account the inherent variations in measurements or calculations that one of ordinary skill in the art would recognize.

[0028] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular form is also intended to include the plural form, unless the context clearly states otherwise. It will be further understood that the terms "comprise", "include" or "have" and their variations when used in this specification indicate the presence of stated features, quantities, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, parts and / or combinations thereof. As used herein, the singular forms "one" and "an" are intended to also include the plural form, unless the context clearly states otherwise.

[0029] It will be understood that although the terms first, second, etc. may be used herein to describe various members, elements, regions, layers, and / or sections, these members, elements, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one member, element, region, layer, and / or section from another. Thus, for example, the first member, first element, first region, first layer, and / or first section discussed below may be referred to as the second member, second element, second region, second layer, and / or second section without departing from the teachings of the present disclosure.

[0030] For ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to another element or feature illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations shown in the drawings. For example, if an element or feature in a drawing is flipped, an element described as being "below" or "beneath" another element or feature would be positioned "above" or "above" the other element or feature. Thus, the exemplary term "below" may include both above and below orientations.

[0031] Hereinafter, a secondary battery according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0032] Figure 1 is a perspective view showing a secondary battery according to an embodiment of the present disclosure, Figure 2 It is shown Figure 1 A side view of the shape of an electrode assembly in a secondary battery is shown, Figure 3 It is shown Figure 1 Schematic diagram of the assembled state of the cap assembly in the secondary battery shown.

[0033] like Figure 1 and Figure 2 As shown, the secondary battery 10 according to an embodiment of the present disclosure may include a case 300 , an electrode assembly 100 accommodated in the case 300 , and a cap assembly 500 sealing the case 300 .

[0034] The housing 300 may have a substantially rectangular parallelepiped shape, and its upper side surface in the long side direction (eg, Figure 1 Although the open portion (e.g., opening) is not shown in the figure, Figure 1 The outer peripheral portion of the housing 300 shown coupled to the cap assembly 500 may correspond to a substantially open portion. After the electrode assembly 100 and the electrolyte are accommodated (e.g., inserted through the opening) through the open portion, the cap assembly 500 is coupled to seal the housing 300. The housing 300 may include (or may be made of) a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. A secondary battery in which the housing 300 has a substantially hexahedral shape may also be referred to as a prismatic battery.

[0035] like Figure 2 and Figure 3 As shown, the electrode assembly 100 may include a first electrode plate 110 , a second electrode plate 130 , and separators 150 a and 150 b (collectively referred to as separators 150 ).

[0036] The first electrode plate 110 may be a positive electrode or a negative electrode. When the first electrode plate 110 is a positive electrode, a positive electrode active material layer may be formed on both surfaces of the first electrode plate 110, and a negative electrode active material layer may be formed on both sides of the second electrode plate 130. When the first electrode plate 110 is a positive electrode, the second electrode plate 130 may be a negative electrode, and when the first electrode plate 110 is a negative electrode, the second electrode plate 130 may be a positive electrode. Here, an embodiment in which the first electrode plate 110 is a negative electrode is described as an example.

[0037] The first electrode plate 110 may be formed by applying or coating an active material such as graphite or carbon on a substrate including (or made of) a metal foil such as copper, copper alloy, nickel, or nickel alloy. Hereinafter, the active material layer will be referred to as a coating portion. An uncoated portion to which an active material is not applied may be formed on the first electrode plate 110. The first electrode plate 110 may include a first electrode tab 112, i.e., a negative electrode tab, extending from the uncoated portion in one direction by a length (e.g., a predetermined length) (e.g., see Figure 3 ).

[0038] The second electrode plate 130 may be formed by applying or coating an active material such as a transition metal oxide on a substrate including (or made of) a metal foil such as aluminum or an aluminum alloy. An uncoated portion to which the active material is not applied may be formed on the second electrode plate 130. The second electrode plate 130 may include a second electrode tab 132, i.e., a positive electrode tab, extending in one direction from the uncoated portion by a length (e.g., a predetermined length) (e.g., see Figure 3 ).

[0039] The separator 150 is interposed between the first electrode plate 110 and the second electrode plate 130 to prevent a short circuit therebetween and enable movement of lithium ions. The separator 150 may include (or may be made of) polyethylene, polypropylene, or a composite film of polyethylene and polypropylene, but is not limited thereto.

[0040] refer to Figure 2 , the electrode assembly 100 may be configured such that the first electrode plate 110, the second electrode plate 130, and the separator 150 are repeatedly stacked in a 'Z' shape, but the stacking type or arrangement is not limited thereto. The electrode assembly 100 is configured such that any one of the first electrode plate 110 and the second electrode plate 130 may be stacked in a 'Z' shape, and the other of the first electrode plate 110 and the second electrode plate 130 may be disposed between the bent or folded portions. Hereinafter, an embodiment will be described based on the first electrode plate 110 being bent into a 'Z' shape. The structure of the electrode assembly 100 will be described in more detail below.

[0041] like Figure 2As shown, the first electrode plate 110 may include a first electrode plate first coating portion 114, a first electrode plate second coating portion 116, a first electrode plate third coating portion 118, and a first electrode plate Nth coating portion (where N represents the Nth coating portion). Before the first electrode plate 110 is bent and stacked, the first electrode plate first coating portion 114 and the first electrode plate second coating portion 116 are arranged on the same plane. However, when the first electrode plate 110 is alternately bent in one direction and another direction and then stacked in a 'Z' shape, the first electrode plate first coating portion 114 and the first electrode plate second coating portion 116 are arranged to be vertically spaced apart from each other in the stacking direction. In a state where stacking is completed, the first electrode plate first coating portion 114 may be parallel to the first electrode plate second coating portion 116. Similarly, the first electrode plate third coating portion 118 is arranged to be vertically spaced apart from the first electrode plate second coating portion 116, and in a state where stacking is completed, the first electrode plate third coating portion 118 may be parallel to the first electrode plate second coating portion 116. In the same manner, stacking may be performed so that all coating portions until the Nth coating portion become parallel to each other. Bending of the first electrode plate 110 may be performed on an uncoated portion where no coating portion is formed. When the first electrode plate 110 has N coating portions and the N coating portions are stacked, separators 150a and 150b may be provided to prevent the N coating portions from contacting each other and short-circuiting.

[0042] When viewed in a planar state before the first electrode plate 110 is bent, two separators 150a and 150b may be provided to cover the front and rear surfaces of the first electrode plate 110, respectively. Figure 2 As shown, when the first electrode plate 110 is bent and stacked in a 'Z' shape, the separators 150a and 150b are configured to surround (eg, sandwich) the first electrode plate 110 from the top and bottom sides. Figure 2 As shown, the structure obtained after the separators 150a and 150b surround the first electrode plate 110 and are then stacked may have a zigzag shape. A portion formed by bending the first electrode plate 110 and the separator 150 may be defined as a bent region.

[0043] After the separators 150a and 150b surround the first electrode plate 110 and are then stacked, the first bending region 152 between the first electrode plate first coating portion 114 and the first electrode plate second coating portion 116 may be formed in a direction opposite to the second bending region 154 between the first electrode plate second coating portion 116 and the first electrode plate third coating portion 118. For example, the first bending region 152 may be formed in one direction (e.g., Figure 2 The first electrode plate 110 may be bent in a left direction (eg, the left direction), and the second bent region 154 may be formed by bending the first electrode plate 110 in another direction (eg, Figure 2The first electrode plate 110 is bent in the right direction of the first electrode plate 110. In the same manner, the bent regions may be sequentially formed up to the Nth bent region. In the first electrode plate 110 thus bent, the coating portions 134, 136, and 138 of the second electrode plate 130 may be interposed between the portions of the bent first electrode plate 110.

[0044] The second electrode plate 130 may include a second electrode plate first coating portion 134, a second electrode plate second coating portion 136, a second electrode plate third coating portion 138, and a second electrode plate Nth coating portion. Here, the second electrode plate first coating portion 134 is interposed between the first electrode plate first coating portion 114 and the first electrode plate second coating portion 116. Of course, the separators 150a and 150b are interposed between the second electrode plate first coating portion 134 and the first electrode plate first coating portion 114 and between the second electrode plate first coating portion 134 and the first electrode plate second coating portion 116, respectively. Therefore, the second electrode plate first coating portion 134 may be stacked to face the first electrode plate first coating portion 114 and the first electrode plate second coating portion 116, with the separators 150a and 150b interposed therebetween. In the same manner, the second electrode plate second coating portion 136 and the second electrode plate third coating portion 138 are arranged until the Nth coating portion, thereby forming the electrode assembly 100.

[0045] The first electrode plate 110 and the second electrode plate 130 may include a first electrode terminal tab 112 and a second electrode terminal tab 132, respectively, to be electrically connected to the outside. When the electrode assembly 100 is stacked, the first electrode terminal tab 112 and the second electrode terminal tab 132 may be arranged to face one side. The electrode assembly 100 is accommodated in the housing 300 in a state where the first electrode terminal tab 112 and the second electrode terminal tab 132 are arranged in a direction toward the cap assembly 500.

[0046] like Figure 1 As shown, in a state where the electrode assembly 100 is accommodated in the case 300, the cap assembly 500 is coupled to the case 300. The cap assembly 500 may include a cap plate 510 that seals an opening in the case 300, a plug 520 that seals an electrolyte injection opening (e.g., an electrolyte injection hole), a safety vent 530 configured to burst when the internal gas pressure exceeds a reference (e.g., predetermined) level to become a gas discharge passage for discharging internal gas, and a first terminal 540 and a second terminal 550 that are electrically connected to the first electrode tab 112 and the second electrode tab 132, respectively. The cap plate 510 may include the same material as the case 300 (or may be made thereof), and may be coupled to the case 300 by, for example, laser welding.

[0047] In the secondary battery 10 having the above-described structure, heat may be generated inside the secondary battery 10 due to, for example, a high temperature operating environment or overcharging. The distribution and movement of heat inside the secondary battery 10 will now be described. Figure 3 As shown, the heat moves and gathers at the portion where the safety vent 530 of the cap assembly 500 is located. Because the portion where the safety vent 530 is located is thinner than other portions of the cap assembly 500, the heat rises and gathers, and the high-temperature heat becomes concentrated and is discharged toward the safety vent 530. When the heat gathers to one side, the structure that is weaker in resistance to the heat is inevitably affected.

[0048] When evaluating the thermal effect by creating a high temperature environment, after the cover tape of different materials is attached to the outside of the case 300 of the secondary battery 10, the shrinkage of the cover tape generally occurs at the upper end in the direction of the cap assembly 500 of the secondary battery 10. Therefore, in order to reduce or minimize and solve the above-mentioned effects and problems caused by heat, a separator 150 with an improved structure is proposed in the present disclosure.

[0049] Figure 4 is a schematic diagram showing an electrode assembly, to which a separator according to an embodiment of the present disclosure is applied, Figure 5 It is shown Figure 4 A plan view of the partition is shown in the deployed state. Figure 6 is a schematic diagram illustrating an electrode assembly to which a separator according to another embodiment of the present disclosure is applied. Figure 7 is a schematic diagram illustrating an electrode assembly to which a separator according to another embodiment of the present disclosure is applied.

[0050] When assembling the cover assembly 500, as shown in FIG. Figure 3 As shown, the cap assembly 500 is assembled in a state where the first and second electrode tabs 112 and 132 are pressed against the cap plate 510. Therefore, the shape of the separator 150 may be determined in consideration of the distance between the cap plate 510 and the electrode assembly 100 after assembling the cap assembly 500. Figure 4 The partition plate 150 shown has a structure with such consideration.

[0051] like Figure 4 and Figure 5As shown, the separator 150 according to an embodiment of the present disclosure may have a rectangular shape. In addition, the separator 150 may include an extension portion 158 extending outward at a certain interval (e.g., a predetermined interval) on one side of the separator 150 in the longitudinal direction. According to an embodiment of the present disclosure, the separator 150 may include an extension portion 158 extending in a direction in which the gas is discharged to the outside of the shell 300. The extension portion 158 may extend in a rectangular shape. In a state where the winding is completed, the length L2 of the extension portion 158 may be less than the distance L1 between the first electrode tab 112 and the second electrode tab 132. In addition, the width W2 of the extension portion 158 may be less than the distance or gap W1 between the cover plate 510 and the electrode assembly 100 after the cover assembly 500 is assembled (see, for example Figure 3 ). Therefore, the width W2 is shorter than the length L0 of the electrode tab protrusion, and the end of the extension portion 158 located at one side of the cap assembly 500 is formed closer to the cap plate 510 than the electrode assembly 100. When the separator 150 is coupled to the first electrode plate 110, the separator 150 is disposed so that the extension portion 158 faces the first electrode tab 112. According to an embodiment of the present disclosure, the extension portion 158 may be adjacent to the safety vent 530.

[0052] In addition, if Figure 6 As shown, a partition 150' according to another embodiment of the present disclosure may include an extension portion 158a having a Figure 4 The area of ​​the extended portion 158 shown is larger. The edge of the extended portion 158a of the separator 150' may be formed in a round shape, such as a streamline shape or a semicircular shape, rather than an angular shape with protruding corners like the separator 150 with a rectangular shape. The length L3 and the width W3 of the extended portion 158a of the separator 150' may both be greater than the length and width of the extended portion 158 of the separator 150. However, the length L3 of the extended portion 158a of the separator 150' is shorter than the distance L1 between the first electrode tab 112 and the second electrode tab 132, and the width W3 is not greater than the distance W1 between the cap plate 510 and the electrode assembly 100 after assembling the cap assembly 500 (see, for example Figure 3 ). However, in some embodiments, the width W3 may be equal to or greater than the distance W1 between the cap plate 510 and the electrode assembly 100 , and thus, the extension portion 158 a may contact the cap plate 510 .

[0053] In addition, if Figure 7As shown, a separator 150″ according to another embodiment of the present disclosure may include an extension portion 158b having a greater range than a distance L1 between the first electrode tab 112 and the second electrode tab 132. In this embodiment, a length L4 of the extension portion 158b may cover (e.g., may overlap) some or all of the first electrode tab 112 and the second electrode tab 132 along the length direction of the electrode assembly 100. A width W4 of the extension portion 158b may be the same as a width of the extension portion 158 of the separator 150 or an extension portion 158a of the separator 150′. When the length L4 of the extension portion 158b is the same as a length from one end to the other end in the longitudinal direction of the electrode assembly 100 (see, e.g., Figure 7 ), the extension portion 158b may have the same shape as when the size of the partition plate 150 is increased by the size of the extension portion 158b.

[0054] like Figure 3 As shown, the separators 150, 150' and 150" having extension portions 158, 158a and 158b according to the above-described embodiments are configured to respond to contraction or deformation, such as melting, of the separator at a portion where heat rises and gathers. By increasing the area of ​​the separators 150, 150', 150" at the portion where heat rises and gathers, even if the separators 150, 150', 150" shrink or partially melt, sufficient area can be maintained to prevent exposure of the electrode plates. Therefore, a short circuit caused by exposure and contact between the electrode plates can be prevented, and the operational safety of the secondary battery can be improved.

[0055] According to the embodiments of the present disclosure, damage to the separator caused by heat rising and gathering toward the exhaust port of the cap assembly in a high temperature environment can be reduced or minimized. In addition, internal short circuits of the secondary battery can be prevented by reducing or minimizing damage to the separator.

[0056] The above description is for implementing some embodiments of the present disclosure. It will be understood by those skilled in the art that the embodiments described herein should be considered as illustrative rather than limiting, and that various changes may be made in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A secondary battery comprising: an electrode assembly comprising a first electrode plate having a first electrode tab, a second electrode plate having a second electrode tab, and a separator between the first electrode plate and the second electrode plate in a stacking direction; as well as a casing for accommodating the electrode assembly, wherein the partition includes an extending portion extending in a direction in which the gas is discharged to the outside of the housing, wherein the extending portion is between the first electrode tab and the second electrode tab in the stacking direction, and The length of the extending portion is smaller than the distance between the first electrode tab and the second electrode tab, so that there is a gap between the extending portion and the first electrode tab and between the extending portion and the second electrode tab.

2. The secondary battery according to claim 1, further comprising a cap assembly coupled to the opening in the case, The width of the extending portion is smaller than a gap between the cap assembly and the electrode assembly. 3 . The secondary battery according to claim 2 , wherein one end of the extending portion facing the cap assembly is closer to the cap assembly than the electrode assembly.

4. The secondary battery according to claim 2, wherein the cap assembly includes a safety vent, and The extended portion is adjacent to the safety vent. 5 . The secondary battery according to claim 1 , wherein a width of the extending portion is smaller than a width of the electrode assembly. 6 . The secondary battery according to claim 1 , wherein a width of the extending portion is smaller than a width of the electrode assembly and greater than a width of the first electrode tab or the second electrode tab. 7 . The secondary battery according to claim 1 , wherein an edge of the extending portion has an arc shape.

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