Secondary battery and battery module including the same

Abstract

The present invention relates to a secondary battery and a battery module comprising the same, and relates to a secondary battery capable of reducing or supporting stress generated in a core unit of an inner winding core type electrode assembly during charging / discharging of the secondary battery, and a battery module comprising the same, to prevent irreversible electrode deformation in the core unit and to prevent collapse of the core unit that may occur due to accumulation of irreversible electrode deformation.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2022-0121207 filed on September 23, 2022 and Korean Patent Application No. 10-2023-0119979 filed on September 8, 2023, which are hereby incorporated by reference in their entirety. Technical Field

[0004] The present invention relates to a secondary battery and a battery module including the same, and more particularly, to a secondary battery and a battery module including the same, wherein stress generated in a core of an internal jellyroll-type electrode assembly during charge and discharge of the secondary battery is relieved and supported to prevent irreversible electrode deformation from occurring in the core and to prevent collapse of the core that may occur due to accumulation of the irreversible electrode deformation. Background Art

[0005] Secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or prismatic metal can and pouch-type batteries in which an electrode assembly is embedded in a pouch-type case made of an aluminum laminate sheet according to the shape of the battery case.

[0006] In addition, the electrode assembly embedded in the battery case can be a rechargeable and dischargeable power generation element having a stacked structure of positive electrode / separator / negative electrode, and can be classified into: a core-rolled electrode assembly, in which long sheet-like positive and negative electrodes coated with active materials are wound together with a separator interposed therebetween; a stacked electrode assembly, in which a plurality of positive and negative electrodes each having a predetermined size are stacked in sequence with a separator interposed therebetween; and a stacked / folded electrode assembly, in which a double cell or a full cell is wound in which positive and negative electrodes of predetermined units are stacked with a separator interposed therebetween.

[0007] Among them, the jelly roll type electrode assembly is widely manufactured because the jelly roll type electrode assembly is easy to manufacture and has the advantage of high energy density per unit weight. The jelly roll type electrode assembly can be manufactured by assembling a stack in which long sheet-shaped positive and negative electrodes are stacked and a separator is interposed therebetween, and winding the electrode stack in the longitudinal direction of the sheet in a state where the core is in contact with one end of the electrode stack. In addition, the jelly roll type electrode assembly can be inserted into a battery case provided as a cylindrical metal can to form a cylindrical secondary battery.

[0008] As technology develops, cylindrical secondary batteries are becoming increasingly high capacity, and as a result, there is a shortage of space available for battery elements such as electrodes. Therefore, there is a need for a method of effectively alleviating stress problems caused by stress in cylindrical battery cores, such as structural collapse phenomena occurring inside a jellyroll-type electrode assembly due to shrinkage and expansion of electrodes.

[0009] Figure 1 is a cross-sectional view illustrating an example of a cylindrical secondary battery according to the prior art. Figure 1 , the cylindrical secondary battery includes a jelly roll type electrode assembly 10 formed by alternately stacking and winding electrodes and separators, and a can case 20 accommodating the jelly roll type electrode assembly. In addition, a core portion 11 is formed at the winding center of the jelly roll type electrode assembly 10. The core portion 11 may be an empty space formed by winding a laminate of electrodes and separators using a winding core to form the jelly roll type electrode assembly 10 and then removing the winding core.

[0010] Figure 2 It is along Figure 1 A cross-sectional view taken along the line AA'. Figure 2 , Figure 2 (a) illustrates the initial state of the core portion 11 of the jellyroll type electrode assembly 10 before collapse. Figure 2 When charging and discharging are performed in the state shown in (a), the electrode assembly 10 and the core 11 of the electrode assembly 10 repeatedly expand and contract. As a result, the electrode of the core 11 is deformed or collapsed due to accumulation of deformation. Figure 2 (b) illustrates a state where the core 11 is deformed and collapsed.

[0011] The problem is that if deformation or collapse occurs inside the core 11 of the electrode assembly 10, there is a risk of internal short circuits that may cause micro short circuits or explosions, such as separator tearing due to electrode edges. Summary of the invention

[0012] Technical issues

[0013] The present invention has been invented to solve the above-mentioned problems, and an object of the present invention is to provide a secondary battery and a battery module including the secondary battery, in which stress generated in the core of an internal jellyroll type electrode assembly during charging and discharging of the secondary battery is relieved and supported to prevent irreversible electrode deformation from occurring in the core and to prevent collapse of the core that may occur due to accumulation of irreversible electrode deformation.

[0014] In addition, the present invention provides a secondary battery and a battery module including the same, in which a problem of winding failure due to the rigidity of a core of an electrode assembly is prevented from occurring when a core-wound type electrode assembly including a core having a small diameter is wound.

[0015] Technical Solution

[0016] The secondary battery according to the present invention includes: a core-wound electrode assembly in which a negative electrode, a positive electrode and a separator are wound; a shell configured to accommodate the electrode assembly; and an electrolyte, which is accommodated in the shell together with the electrode assembly, wherein an expansion band that expands when absorbing the electrolyte is attached to a surface of the separator arranged to surround a core portion, which is the winding center of the electrode assembly, wherein the expansion band includes: a base material; and an adhesive layer, which is arranged on one of the two surfaces of the base material facing the separator, wherein the base material is arranged on the opposite surface of the surface on which the adhesive layer is arranged, and the base material includes a plurality of protrusions, each of which has a protruding shape.

[0017] The base material may include a polymer material.

[0018] One surface of the diaphragm may be a surface facing the core among the two surfaces of the diaphragm.

[0019] The electrode assembly may have a shape in which a first separator, a negative electrode, a second separator, and a positive electrode are sequentially stacked, and an expansion tape may be attached to the second separator.

[0020] The expansion tape may be attached to the diaphragm such that a core-side end of the diaphragm and a core-side end of the expansion tape coincide with each other.

[0021] The convex portion may have a shape gradually narrowing upward from the lower side based on a cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly.

[0022] The convex portion may have a shape extending in the width direction of the diaphragm, and the plurality of convex portions may be arranged such that an upper side of the convex portion is spaced apart from an adjacent convex portion in the longitudinal direction of the diaphragm and a lower side of the convex portion contacts the adjacent convex portion in the longitudinal direction of the diaphragm.

[0023] The protrusion may have a shape of a semicircle or a portion of a circle based on a cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly.

[0024] The protrusion may have a trapezoidal shape based on a cross-sectional view taken along a plane perpendicular to a winding axis of the electrode assembly.

[0025] The trapezoidal shape may be an equilateral trapezoidal shape.

[0026] The core may have a diameter (P) of 3.2 to 3.6 mm, and the base material may have a thickness (t) of 30 to 50 um.

[0027] The length (U) of the lower side of the convex portion having a trapezoidal shape may be 0.1 mm to 0.3 mm, and

[0028] The angle (θ) of the convex portion, which is an angle formed by intersecting two straight lines formed by extending a pair of non-parallel opposite sides of the trapezoidal shape, may be 6.5 degrees to 7.9 degrees.

[0029] The length (U) of the lower side of the convex portion having a trapezoidal shape may be 0.4 mm to 0.6 mm, and

[0030] The angle (θ) of the convex portion, which is an angle formed by intersecting two straight lines formed by extending a pair of non-parallel opposite sides of the trapezoidal shape, may be 16 to 20 degrees.

[0031] A battery module according to the present invention includes the above-mentioned secondary battery and a case accommodating a plurality of secondary batteries.

[0032] Beneficial Effects

[0033] In a secondary battery and a battery module including the secondary battery according to the present invention, stress generated in the core of an internal jellyroll-type electrode assembly during charge and discharge of the secondary battery can be relieved and supported to prevent irreversible electrode deformation occurring in the core and collapse of the core that may occur due to accumulation of irreversible electrode deformation.

[0034] In addition, in the secondary battery and the battery module including the same according to the present invention, when a jelly-wound electrode assembly including a core having a small diameter is wound, a problem of winding failure due to the rigidity of the core of the electrode assembly can be prevented from occurring. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a cross-sectional view illustrating an example of a cylindrical secondary battery according to the related art.

[0036] Figure 2 It is along Figure 1 A cross-sectional view taken along line AA'.

[0037] Figure 3 According to the first embodiment of the present invention, Figure 1 A cross-sectional view of the secondary battery taken along line AA'.

[0038] Figure 4 is a perspective view illustrating a state in which a jelly jelly-type electrode assembly of a secondary battery according to Embodiment 1 of the present invention is unfolded and exploded.

[0039] Figure 5 yes Figure 3 An enlarged stereogram of portion B of FIG.

[0040] Figure 6 is along Figure 5A side view of the configuration when viewed in the direction of arrow E.

[0041] Figure 7 1 is a side view illustrating a state where the core-wound jelly-roll type electrode assembly is started in the secondary battery according to the first embodiment of the present invention.

[0042] Figure 8 is an example Figure 7 A side view of another modified example of the embodiment is shown.

[0043] Fig. 9 is a side view illustrating a state in which an expansion tape is attached in a secondary battery according to Embodiment 2 of the present invention.

[0044] Fig.10 is a side view illustrating a state in which an expansion tape is attached in a secondary battery according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0045] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited or constrained by the following embodiments.

[0046] In order to explain the present invention clearly, the detailed description of the parts irrelevant to the description or the related known technology which may unnecessarily obscure the subject of the present invention is omitted, and in this specification, the reference numerals are added to the parts in each drawing. In this case, the same or similar reference numerals are given to the same or similar elements throughout the specification.

[0047] Furthermore, the terms or words used in the present specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms in order to best describe and interpret his or her invention.

[0048] Implementation Method 1

[0049] Figure 1 is a cross-sectional view illustrating an example of a cylindrical secondary battery according to the related art. Figure 2 It is along Figure 1 A cross-sectional view taken along line AA'. Figure 3 According to the first embodiment of the present invention, Figure 1 A cross-sectional view of the secondary battery taken along line AA'. Figure 4 is a perspective view illustrating a state in which a jelly jelly-type electrode assembly of a secondary battery according to Embodiment 1 of the present invention is unfolded and exploded. Figure 5 yes Figure 3An enlarged stereogram of portion B of FIG. Figure 6 is along Figure 5 A side view of the configuration when viewed in the direction of arrow E. Figure 7 1 is a side view illustrating a state where the core-wound jelly-roll type electrode assembly is started in the secondary battery according to the first embodiment of the present invention.

[0050] Reference Figure 3 , Figure 4 and Figure 7 , the secondary battery according to Embodiment 1 of the present invention includes an electrode assembly 110 , a case, and an electrolyte, and an expansion tape 130 is attached to a core 120 which is a central portion of the electrode assembly 110 .

[0051] The electrode assembly 110 may be a core-wound electrode assembly 110 formed by alternately stacking and winding the negative electrode 112, the positive electrode 114, and the separator 115. The case may be a case that accommodates the electrode assembly. The case may be a can case having a cylindrical shape. The electrolyte (not shown) may be a liquid accommodated in the case together with the electrode assembly 110.

[0052] In addition, the core portion 120 is formed at the winding center of the jellyroll type electrode assembly 110. The core portion 120 may be an empty space defined by winding a stack of electrodes and the separator 115 around a core K to form the jellyroll type electrode assembly 110 and then removing the core K.

[0053] In the secondary battery according to Embodiment 1 of the present invention, the expansion tape 130 is attached to one side of the separator 115 disposed to surround the core 120 which is the winding center of the electrode assembly 110. Here, the one side of the separator 115 may be a surface facing the core 120 of both surfaces of the separator 115.

[0054] Specifically, refer to Figure 4 and Figure 7 , the electrode assembly 110 can be set in a shape in which the first separator 111, the negative electrode 112, the second separator 113 and the positive electrode 114 are stacked and wound in sequence. In addition, the expansion tape 130 can be attached to the second separator 113 of the above-mentioned two separators 115. The expansion tape 130 can be attached to the separator 115 inside the core. When attached to the separator 115 inside the core, since there is a distance from the facing part between the positive electrode and the negative electrode, there is no problem of change in battery characteristics because it does not affect the battery reaction. In addition, in terms of the battery manufacturing process, it may be more advantageous because when the core K is maintained in the winding direction W (see Figure 7 ) When winding the core K, the expansion belt 130 serves as a supporting function. Here, the core K is two rods that hold the center of the separator 115 for the winding process. The core K is rotated to form the core-wound type electrode assembly 110 through the winding process, and then the core K is taken away.

[0055] Figure 8 is an example Figure 7 A side view of another modified example of the embodiment shown. Figure 8 As another modified example of the electrode assembly, the electrode assembly 110 may be configured in a shape in which the first separator 111, the positive electrode 114, the second separator 113, and the negative electrode 112 are sequentially stacked and wound. In addition, the expansion tape 130 may also be attached to the second separator 113 of the above two separators 115. The expansion tape 130 may also be attached to the separator 115 inside the core.

[0056] Reference Figure 4 and Figure 5 The expansion tape 130 may be attached to the diaphragm 115 so that the core-side end of the diaphragm 115 to which the expansion tape 130 is attached and the core-side end of the expansion tape 130 coincide with each other (specifically, the expansion tape 130 may be attached to coincide with the core-side end of the second diaphragm 113). Figure 4 The O direction arrow in the figure indicates the core side. The core side may refer to the direction toward the winding center.

[0057] The expansion tape 130 may be a tape that expands when absorbing electrolyte. For example, the expansion tape 130 may include a polymer material. The polymer material may be a material that has the property of absorbing electrolyte but does not react with the electrolyte. Specifically, the polymer material may include a polyurethane (PU) material.

[0058] Specifically, the expansion tape 130 may include a base material 131 and an adhesive layer 132. The adhesive layer 132 may be an adhesive material layer applied to one surface of the base material 131. In addition, specifically, the base material 131 of the expansion tape 130 may include a polymer material. Specifically, the base material 131 may include a polyurethane (PU) material. The base material 131 may be made of another material as long as it absorbs electrolytes so as to expand. The expanded base material 131 may buffer or absorb impact or stress. Alternatively, the base material 131 may be used to resist and support impact or stress. The adhesive layer 132 may be provided on the surface facing the diaphragm 115 of the two surfaces of the base material 131.

[0059] Reference Figure 5 and Figure 6 In the secondary battery according to the embodiment 1 of the present invention, a plurality of concave portions 134 and a plurality of convex portions 133 may be provided on the base material 131. Specifically, the convex portion 133 may be provided on a surface opposite to a surface on which the adhesive layer 132 is provided. The concave portion 134 may have a concave shape. The convex portion 133 may have a relatively high and thick shape compared to the concave portion.

[0060] For reference, the concave portion 134 and the convex portion 133 may be manufactured by laser etching by irradiating a laser beam onto a tape. Alternatively, the concave portion 134 and the convex portion 133 may be manufactured by a pressing method using a mold.

[0061] In the secondary battery according to Embodiment 1 of the present invention, the expansion tape 130 may be attached to the separator 115 provided on the core 120 to relieve or support stress occurring in the core 120 of the inner jellyroll type electrode assembly 110 during charge and discharge of the secondary battery. In addition, as a result, irreversible electrode deformation occurring in the core 120 and collapse of the core 120 due to accumulation of deformation may be prevented.

[0062] Reference Figure 3 , Figure 3 (a) illustrates a state before the core 120 expands and contracts before the electrolyte is injected, and Figure 3 (b) illustrates a state after the core 120 expands and contracts after the electrolyte is injected. Figure 3 (b) Due to the expanded expansion band 130, it can be seen that the core 120 can maintain the shape without being deformed or collapsed even after the expansion and contraction of the core 120 are repeated.

[0063] Figure 6 is along Figure 5 This is a side view of the configuration when viewed in the direction of arrow E. Figure 6 , based on a cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly 110, the convex portion 133 may be formed in a shape in which the width gradually narrows from the lower side to the upper side. Figure 5 , the protrusion 133 may be arranged to extend along the width direction Y of the diaphragm 115. Figure 4 As shown, the width of the expansion band 130 can be the same as the width of the diaphragm 115. Figure 6 , the length J of the expansion tape 130 based on the longitudinal direction L of the separator 115 may be set to be neither too long nor too short. Specifically, the length J of the expansion tape 130 may be determined within a range that does not interfere with the battery reaction.

[0064] In addition, refer to Figure 5 and Figure 6 , the plurality of protrusions 133 may be arranged such that the upper side of the protrusion 133 may be spaced apart from the adjacent protrusion 133 in the longitudinal direction L of the diaphragm 115 , and the lower side of the protrusion 133 contacts the adjacent protrusion 133 in the longitudinal direction L of the diaphragm 115 .

[0065] Reference Figure 6 Specifically, the convex portion 133 may be provided in a trapezoidal shape based on a cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly 110. Here, the trapezoid may most preferably be an equilateral trapezoid.

[0066] If the shape of the protrusion 133 is formed in this manner, when winding the jellyroll type electrode assembly 110 including the core 120 having a small diameter, the problem of winding failure due to the rigidity of the expansion tape 130 attached to the core 120 of the electrode assembly 110 can be prevented from occurring.

[0067] Specifically, the expansion band 130 must have a certain degree of rigidity to prevent the collapse of the core 120, but such rigidity may make it difficult to form a winding in the core 120. This is because the rigidity of the expansion band 130 is used to apply a force to loosen the winding again.

[0068] In addition, during the electrolyte injection operation after inserting the jellyroll type electrode assembly 110, the expansion tape 130 may expand in volume, and such expansion of the expansion tape 130 may act as a force in the unwinding direction. The convex portion 133 of the present invention may solve the problem of winding loosening or not being formed correctly.

[0069] Specifically, since the spaces between the protrusions 133 serve to weaken the rigidity or repulsive force of the expansion band 130 , the problem of winding being loosened or not being formed correctly due to the rigidity of the expansion band 130 can be solved.

[0070] Reference Figure 3 and Figure 6 , in the secondary battery according to the embodiment 1 of the present invention, the diameter P of the core 120 may be 3.2 mm to 3.6 mm, and the thickness t of the base material 131 may be 30 um to 50 um (in micrometers). In addition, the thickness of the base material layer excluding the convex portion may be about 1 / 4 to 1 / 3 of the thickness of the entire base material layer. This may be the most favorable thickness range in which the adhesive layer is not exposed but the convex portion is formed.

[0071] In addition, the length U of the lower side of the convex portion 133 having a trapezoidal shape may be 0.1 mm to 0.3 mm. In this case, the angle θ of the convex portion 133, which is an angle formed by intersecting two straight lines extending from a pair of non-parallel opposite sides of the trapezoidal shape, may be 6.5 degrees to 7.9 degrees.

[0072] For reference, the calculation method is explained as follows. When the diameter P of the core 120 is about 3.2 mm, the circumference of the core 120 can be 3.2 mm × 3.14 (pi) = about 10 mm. When it is assumed that the length U of the lower side of the protrusion 133 is about 0.2 mm, if 10 mm is divided by 0.2 mm, about 50 protrusions 133 can be formed around the core 120. Therefore, if 360 degrees is divided by 50, the angle of the protrusion 133 can be obtained to be about 7.2 degrees. In this case, if a tolerance range of about 10% is applied, 7.2-0.7 = 6.5 degrees, and 7.2 + 0.7 = 7.9 degrees.

[0073] In addition, the length U of the lower side of the convex portion 133 having a trapezoidal shape may be 0.4 mm to 0.6 mm. In this case, the angle θ of the convex portion 133, which is an angle formed by intersecting two straight lines extending from a pair of non-parallel opposite sides of the trapezoidal shape, may be 16 degrees to 20 degrees.

[0074] This situation can be calculated similarly. When the diameter P of the core 120 is about 3.2 mm, the circumference of the core 120 can be 3.2 mm × 3.14 (pi) = about 10 mm. When it is assumed that the length U of the lower side of the protrusion 133 is about 0.5 mm, if 10 mm is divided by 0.5 mm, about 20 protrusions 133 can be formed around the core 120. Therefore, if 360 degrees is divided by 20, the angle of the protrusion 133 can be obtained to be about 18 degrees. In this case, if a tolerance range of about 10% is applied, 18-2 = 16 degrees, and 18 + 2 = 20 degrees.

[0075] In addition, a battery module according to the present invention may be formed to include the secondary battery according to Embodiment 1 of the present invention described above and a case accommodating a plurality of secondary batteries.

[0076] Implementation Method 2

[0077] Fig. 9 is a side view illustrating a state in which an expansion tape is attached in a secondary battery according to Embodiment 2 of the present invention.

[0078] Embodiment 2 of the present invention is different from Embodiment 1 in that the shape of the convex portion is circular instead of trapezoidal.

[0079] The contents repeated with Embodiment Mode 1 will be omitted as much as possible, and Embodiment Mode 2 will be described focusing on the differences. That is, it is obvious that the contents not described in Embodiment Mode 2 can be supplemented as the contents of Embodiment Mode 1 if necessary.

[0080] Reference Fig. 9In the secondary battery according to Embodiment 2 of the present invention, the convex portion 233 may be formed in the shape of a portion of a semicircle or a circle based on a cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly.

[0081] exist Fig. 9 , it is shown that the convex portion 233 is formed in a semicircular shape on the base material. The base material 231 on which the semicircular convex portion 233 is formed can be attached to one surface of the diaphragm 215 as in Embodiment 1, and the adhesive layer 232 can be formed on one surface of the base material 231 to adhere to the diaphragm 215.

[0082] When the convex portion is formed in this manner, there is a difference in that the edge portion is relatively absent or small compared to a trapezoidal shape.

[0083] Implementation 3

[0084] Fig.10 is a side view illustrating a state in which an expansion tape is attached in a secondary battery according to Embodiment 3 of the present invention.

[0085] When compared with Embodiments 1 and 2 of the present invention, it is different from Embodiments 1 and 2 in that the object of the present invention is achieved by attaching a plurality of expansion bands, each of which has a narrow width.

[0086] The contents repeated with Embodiment Mode 1 and Embodiment Mode 2 will be omitted as much as possible, and Embodiment Mode 3 will be described focusing on the differences. That is, it is obvious that the contents not described in Embodiment Mode 3 can be supplemented with the contents of Embodiment Mode 1 and Embodiment Mode 2 as necessary.

[0087] Reference Fig.10 , the secondary battery according to Embodiment 3 of the present invention may include: a core-wound electrode assembly 110 formed by winding a negative electrode, a positive electrode, and a separator; a case that accommodates the electrode assembly; an electrolyte that is accommodated in the case together with the electrode assembly 110, and a plurality of expansion bands 330 that expand when absorbing the electrolyte may be attached at predetermined intervals on one surface of the separator disposed around a core portion that is a winding center of the electrode assembly 110. In addition, each expansion band 330 may include a base material 331 and an adhesive layer 332 formed on a surface facing the separator among both surfaces of the base material.

[0088] That is, the present invention is characterized in that each expansion tape 330 has a thin width and is attached in multiple rows. In Embodiment 3, one expansion tape 330 can be used as one convex portion 133 and 233 in Embodiments 1 and 2.

[0089] When formed in this manner, it is not necessary to individually implement the concave and convex portions using a method such as laser etching, and therefore, manufacturing convenience can be achieved. In other words, several expansion bands 330 can be simply attached without the need for precise or expensive equipment (e.g., a separate laser etching device), thereby making manufacturing and use easier.

[0090] While embodiments of the present invention have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the following claims.

[0091] [Explanation of Reference Numerals]

[0092] 100: Secondary battery

[0093] 110: Electrode assembly

[0094] 111: First Diaphragm

[0095] 112: Positive

[0096] 113: Second diaphragm

[0097] 114: Negative electrode

[0098] 115, 215, 315: Diaphragm

[0099] 120: Core

[0100] 130, 230, 330: expansion belt

[0101] 131, 231, 331: Basic materials

[0102] 132, 232, 332: Adhesive layer

[0103] 133, 233: convex part

[0104] 134, 234: concave part

[0105] K: Core

[0106] W: Winding direction

Claims

1. A secondary battery, comprising: A core-wound electrode assembly in which a negative electrode, a positive electrode and a separator are wound; a housing configured to accommodate the electrode assembly; as well as an electrolyte, the electrolyte being contained in the housing together with the electrode assembly, wherein an expansion band that expands when absorbing the electrolyte is attached to one surface of the separator disposed around a core portion that is a winding center of the electrode assembly, Wherein, the expansion belt comprises: Base materials; and an adhesive layer provided on one of the two surfaces of the base material facing the separator, wherein the base material is provided on a surface opposite to a surface on which the adhesive layer is provided, and the base material includes a plurality of concave portions and a plurality of convex portions.

2. The secondary battery according to claim 1, wherein The base material includes a polymer material.

3. The secondary battery according to claim 1, wherein One surface of the diaphragm is a surface facing the core among the two surfaces of the diaphragm.

4. The secondary battery according to claim 3, wherein The electrode assembly has a shape in which a first separator, a negative electrode, a second separator and a positive electrode are sequentially stacked, and The expansion band is attached to the second diaphragm.

5. The secondary battery according to claim 3, wherein The electrode assembly has a shape in which a first separator, a positive electrode, a second separator and a negative electrode are sequentially stacked, and The expansion band is attached to the second diaphragm.

6. The secondary battery according to claim 1, wherein The expansion band is attached to the diaphragm so that a core-side end portion of the diaphragm and a core-side end portion of the expansion band coincide with each other.

7. The secondary battery according to claim 1, wherein The convex portion has a shape gradually narrowing upward from a lower side based on a cross-sectional view taken along a plane perpendicular to a winding axis of the electrode assembly.

8. The secondary battery according to claim 7, wherein The convex portion has a shape extending in the width direction of the diaphragm, and The plurality of convex portions are arranged such that upper sides of the convex portions are spaced apart from adjacent convex portions in the longitudinal direction of the diaphragm, and lower sides of the convex portions are in contact with adjacent convex portions in the longitudinal direction of the diaphragm.

9. The secondary battery according to claim 7, wherein The convex portion has a shape of a portion of a semicircle or a circle based on the cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly.

10. The secondary battery according to claim 7, wherein The convex portion has a trapezoidal shape based on the cross-sectional view taken along a plane perpendicular to the winding axis of the electrode assembly.

11. The secondary battery according to claim 10, wherein The trapezoidal shape is an equilateral trapezoidal shape.

12. The secondary battery according to claim 10, wherein The core has a diameter (P) of 3.2 mm to 3.6 mm, and The base material has a thickness (t) of 30 um to 50 um.

13. The secondary battery according to claim 12, wherein: The length (U) of the lower side of the convex portion having the trapezoidal shape is 0.1 mm to 0.3 mm, and The angle (θ) of the convex portion, which is an angle formed by intersecting two straight lines extending from a pair of non-parallel opposite sides of the trapezoidal shape, is 6.5 degrees to 7.9 degrees.

14. The secondary battery according to claim 12, wherein: The length (U) of the lower side of the convex portion having the trapezoidal shape is 0.4 mm to 0.6 mm, and The angle (θ) of the convex portion, which is an angle formed by intersecting two straight lines extending from a pair of non-parallel opposite sides of the trapezoidal shape, is 16 to 20 degrees.

15. A secondary battery, comprising: A core-wound electrode assembly in which a negative electrode, a positive electrode and a separator are wound; a housing configured to accommodate the electrode assembly; as well as an electrolyte, the electrolyte being contained in the housing together with the electrode assembly, wherein a plurality of expansion bands that expand when absorbing the electrolyte are attached at predetermined intervals to one surface of the separator disposed around a core portion that is a winding center of the electrode assembly, Wherein, each of the expansion bands comprises: Base materials; and An adhesive layer is provided on a surface facing the separator among the two surfaces of the base material.

16. A battery module, comprising: The secondary battery according to claim 1; as well as A housing houses a plurality of secondary batteries.

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