Battery cell

Abstract

The battery cell comprises: an electrode assembly comprising a positive electrode, a negative electrode and a diaphragm; and an exterior material that accommodates the electrode assembly therein, and is provided with a cutout portion in a predetermined cutout region thereof, the cutout portion including: a first cutout portion having a predetermined thickness, a second cutout portion having a predetermined thickness, and a third cutout portion having a predetermined thickness; and a second cutout portion intersecting with one end of the first cutout portion to form a first intersection point and intersecting with the other end opposite to the one end of the first cutout portion to form a second intersection point, the thickness of the second cutout portion being different from the thickness of the first cutout portion.

Description

Technical Field

[0001] The present disclosure relates to a battery cell, and in particular to a battery cell having a notch. Background Art

[0002] Secondary batteries are batteries that convert electrical energy into chemical energy and store it so that it can be reused many times through charging and discharging. Secondary batteries are widely used throughout the industry due to their economical and environmentally friendly characteristics. In particular, lithium secondary batteries (Lithium Secondary Battery) are widely used throughout the industry, including portable devices that require high-density energy.

[0003] The working principle of lithium secondary batteries is electrochemical redox reaction. That is, the working principle of lithium secondary batteries is to generate electricity through the movement of lithium ions (Lithium Ion), and to charge in the process opposite to this process. In the case of lithium secondary batteries, the phenomenon that lithium ions in the negative electrode (Anode) escape and move to the positive electrode (Cathode) through the electrolyte and separator is called discharge. And, the process opposite to this phenomenon is called charging.

[0004] During repeated charging and discharging, a secondary battery may experience swelling, which increases its internal pressure and generates a large amount of heat. Since this swelling may cause explosion or fire, a solution for regulating the internal pressure of the secondary battery is needed. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The problem to be solved by the present disclosure is to provide a battery cell with improved stability by adjusting the internal pressure.

[0007] In addition, an object of the present disclosure is to provide a battery cell whose notch portion can be opened smoothly.

[0008] In addition, the present disclosure can also be widely used in electric vehicles, battery charging stations, other green technology fields such as solar power generation and wind power generation using batteries. In addition, the present disclosure can be used in eco-friendly electric vehicles and hybrid vehicles that prevent climate change by suppressing air pollution and greenhouse gas emissions.

[0009] (II) Technical solution

[0010] The battery cell disclosed herein comprises: an electrode assembly, comprising a positive electrode, a negative electrode and a separator; and an outer packaging material, wherein the electrode assembly is accommodated inside the outer packaging material, and a notch portion is provided in a preset notch area of ​​the outer packaging material, wherein the notch portion comprises: a first notch portion, having a preset thickness; and a second notch portion, intersecting with one end of the first notch portion to form a first intersection point, and intersecting with the other end opposite to the one end of the first notch portion to form a second intersection point, and the thickness of the second notch portion is different from the thickness of the first notch portion.

[0011] The second notch portion may have a thickness thinner than that of the first notch portion.

[0012] The thickness of the first notch portion may be thicker from the first intersection toward a center portion formed between the first intersection and the second intersection, and may be thinner from the center portion toward the second intersection.

[0013] The first notch portion may include a step.

[0014] The first notch portion may be formed to extend in one direction within the notch region.

[0015] The first notch portion may be provided in a V-shape within the notch region.

[0016] The two notch portions may include a first sub-notch portion forming the first intersection and a second sub-notch portion forming the second intersection. The thickness of the first sub-notch portion may become thinner as it is farther from the first intersection, and the thickness of the second sub-notch portion may become thinner as it is farther from the second intersection.

[0017] The first sub-notch portion and the second sub-notch portion may be formed symmetrically with respect to the first notch portion.

[0018] The second notch portion may be formed in a curved shape.

[0019] The second notch portion may have a shape bent at the first intersection and the second intersection, respectively.

[0020] The second notch portion may be formed closer to an edge of the notch region than the first notch portion.

[0021] The first notch portion and the second notch portion may be connected to each other to form a U shape.

[0022] (III) Beneficial effects

[0023] The present disclosure may provide a battery cell having improved stability by adjusting internal pressure.

[0024] In addition, a battery cell in which the notch portion can be opened smoothly can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A battery cell according to one embodiment of the present disclosure is shown.

[0026] Figure 2 An exploded view of a battery cell according to one embodiment of the present disclosure is shown.

[0027] Figure 3 A cutout portion according to one embodiment of the present disclosure is shown.

[0028] Figures 4 to 6 Shown along Figure 3 The cross section is taken along the AA' direction.

[0029] Figure 7 A notch portion according to another embodiment of the present disclosure is shown.

[0030] Figure 8 Shown along Figure 7 The cross section is taken along the BB' direction.

[0031] Figures 9a to 9d Various embodiments of the notch portion of the present disclosure are shown.

[0032] Description of reference numerals:

[0033] 100: Battery cell 11: Battery cell connector

[0034] 12: Exterior material 20: Notch area

[0035] 21: Notch 150: Electrode assembly

[0036] 210: first notch 220: second notch

[0037] 221: first sub-notch 222: second sub-notch DETAILED DESCRIPTION

[0038] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings, which are merely exemplary and the present disclosure is not limited to the specific embodiments described exemplarily.

[0039] Specific terms used in this specification are only used for convenience of description and are not intended to limit the illustrated embodiments.

[0040] For example, expressions such as “same” and “identical” indicate not only a strictly identical state but also a state where there is a tolerance or a difference having the same degree of function.

[0041] For example, expressions such as "in a certain direction", "along a certain direction", "side by side", "vertical", "centered on...", "concentric" or "coaxial" indicating relative or absolute settings not only strictly indicate such an arrangement but also indicate a state in which there is a tolerance or a relative displacement at an angle or distance with the same degree of functionality.

[0042] In order to explain the present disclosure, the following description is based on a spatial orthogonal coordinate system in which the X-axis, Y-axis and Z-axis are orthogonal to each other. The directions of each axis (X-axis direction, Y-axis direction, Z-axis direction) refer to the directions on both sides of the extension of each axis.

[0043] The X direction, the Y direction, and the Z direction mentioned below are explained for clear understanding of the present disclosure, and of course, each direction may be defined differently according to different standards.

[0044] The terms such as "first, second, third" used before the components mentioned below are only used to avoid confusion of the components, and have nothing to do with the order, importance, or master-slave relationship between the components. For example, the present invention may include only the second component but not the first component.

[0045] Unless the context clearly indicates otherwise, an expression in the singular used in this specification includes an expression in the plural.

[0046] Figure 1 A battery cell 100 according to an embodiment of the present disclosure is shown. Figure 2 An exploded view of a battery cell 100 according to one embodiment of the present disclosure is shown.

[0047] The battery cell 100 described in this specification refers to a secondary battery that can be repeatedly used by charging and discharging electric energy. As an example, the battery cell 100 may be a lithium secondary battery, but is not limited thereto.

[0048] The battery cell 100 may be classified into a pouch-shaped secondary battery, a prismatic secondary battery, or a cylindrical secondary battery according to the shape. Figure 1 For the sake of convenience, this specification takes a prismatic secondary battery as an example, but is not limited thereto.

[0049] The battery cell 100 disclosed in the present invention includes: an electrode assembly including a positive electrode, a negative electrode and a separator; and an outer packaging material 12, wherein the electrode assembly is accommodated inside the outer packaging material, and a notch portion 21 is provided in a preset notch area 20 of the outer packaging material 12, wherein the notch portion 21 includes: a first notch portion 210 having a preset thickness; and a second notch portion 220, which intersects with one end of the first notch portion 210 to form a first intersection point P1, and intersects with the other end opposite to the one end of the first notch portion 210 to form a second intersection point P2, and the thickness of the second notch portion 220 is different from the thickness of the first notch portion 210.

[0050] The battery cell 100 includes an electrode assembly. Figure 2 The electrode assembly may include a positive electrode 151, a negative electrode 153, and a separator 152. According to the stacking method of the positive electrode 151, the negative electrode 153, and the separator 152, the electrode assembly may be classified into a stacking type, a winding type, a stack-folding type, or a Z-stacking type.

[0051] The type of the electrode assembly included in the battery cell 100 of the present disclosure is not limited. In other words, the electrode assembly included in the battery cell 100 of the present disclosure may be an electrode assembly manufactured in one of a stacking type, a winding type, a stack-folding type, and a Z-stack type.

[0052] The positive electrode 151 and the negative electrode 153 may include a current collector. The positive electrode 151 may include a positive electrode current collector, and the negative electrode 153 may include a negative electrode current collector. The current collector may contain a known conductive material within a range that does not cause a chemical reaction in a lithium secondary battery. For example, the current collector may contain one of stainless steel, nickel (Ni), aluminum (Al), titanium (Ti), copper (Cu), and alloys thereof, and may be provided in various forms such as a film, a sheet, and a foil.

[0053] The positive electrode 151 and the negative electrode 153 may include active materials. The positive electrode 151 may include a positive active material, and the negative electrode 153 may include a negative active material. The positive active material may be a material in which lithium ions can be embedded and de-embedded, and the negative active material may be a material in which lithium ions can be occluded and de-embedded. For example, the positive active material may be a lithium metal oxide, and the negative active material may be a carbon-based material such as crystalline carbon, amorphous carbon, a carbon composite, carbon fiber, a lithium alloy, silicon (Si), and tin (Sn).

[0054] In addition, the positive electrode 151 and the negative electrode 153 may include a binder and a conductive material, respectively, to improve mechanical stability and conductivity.

[0055] The separator 152 may be configured to prevent electrical short circuit between the positive electrode 151 and the negative electrode 153 and allow ion flow. The type of the separator is not particularly limited and may include a porous polymer film. For example, the separator may include a porous polymer film or a porous nonwoven fabric.

[0056] The electrolyte may include an electrolyte. The electrolyte may be a non-aqueous electrolyte. The electrolyte may include a lithium salt and an organic solvent. The electrolyte may also include an additive. The additive may form a film on the positive electrode or the negative electrode through a chemical reaction inside the battery. For example, a positive electrode interface film may be formed on the positive electrode, and a negative electrode interface film may be formed on the negative electrode.

[0057] Reference Figure 2 , the outer packaging material 12 may contain an electrode assembly inside. The outer packaging material 12 may contain an electrode assembly and an electrolyte inside. The outer packaging material 12 may include an outer insulating layer made of a polymer material, an inner adhesive layer, and a metal layer interposed between the outer insulating layer and the inner adhesive layer. The outer packaging material 12 may include a material with high mechanical rigidity to protect the battery cell 100 from external impact. For example, the housing may include an aluminum layer.

[0058] The exterior material 12 may include a main body 13 accommodating the electrode assembly and cover parts 14a and 14b covering the main body 13. The cover part 14 may include a cell tab 11 for electrically connecting the electrode assembly to the outside.

[0059] Reference Figure 2 The main body 13 may include an opening 15. Both sides of the main body 13 may be open. Figure 2 , the two side surfaces of the main body 13 may be open toward the Y direction. The electrode assembly and the electrolyte may be accommodated inside the outer packaging material 12 through the opening 15. For example, the opening 15 may have a hexahedral shape and its two side surfaces may be open along the Y direction. The cover 14 may cover the two side surfaces of the opening of the main body 13. The main body 13 and the cover 14 may be combined to close the accommodation space of the outer packaging material 12.

[0060] The cover parts 14a, 14b may cover the main body 13. In other words, the cover parts 14a, 14b may cover both sides of the opening of the main body 13 to protect components accommodated inside the main body 13. The main body 13 and the cover parts 14a, 14b may be combined or sealed with each other.

[0061] The battery cell 100 may further include a battery cell connector 11 protruding outside the outer packaging material 12 to electrically connect to the outside. The battery cell connector 11 may be provided on the cover 14. The battery cell 100 may include a plurality of cover portions 14a, 14b and a plurality of battery cell connectors 11a, 11b. The plurality of cover portions 14a, 14b may be provided with respective battery cell connectors 11a, 11b.

[0062] The cell connectors 11 may be respectively connected to the positive electrode and the negative electrode of the cell 100. The cell connectors 11 may include a positive electrode connector 11a connected to the positive electrode and a negative electrode connector 11b connected to the negative electrode.

[0063] Figure 3 A notch portion 21 according to one embodiment of the present disclosure is shown.

[0064] The notch portion 21 includes a first notch portion 210 and a second notch portion 220. The first notch portion 210 may have a preset thickness. The thickness of the notch portion 21 refers to the length along the thickness direction of the exterior material 12. For example, referring again to Figure 1 The thickness of the notch 21 refers to the length of the notch 21 along the Z direction.

[0065] The internal pressure of the battery cell 100 can be adjusted by the notch portion 21. The battery cell 100 can be used multiple times by repeated charging and discharging. The gas generated during this process may cause the internal pressure of the battery cell 100 to increase. If the gas continues to exist without being removed, the battery cell 100 may explode. Therefore, it is necessary to appropriately adjust the pressure of the battery cell 100 to ensure the safe use of the battery cell 100.

[0066] A notch portion 21 may be provided on one side of the outer packaging material 12 so that gas is discharged through the notch portion 21. In other words, the shape of the notch portion 21 may be changed based on the internal pressure of the outer packaging material 12. The notch portion 21 may be formed in a preset notch region 20 of the outer packaging material 12. The notch region 20 may be any region of the outer packaging material 12. For example, the notch region 20 may be located in the main body portion 13 or the cover portion 14.

[0067] Specifically, when the internal pressure of the outer packaging material 12 increases and reaches the fracture pressure, the notch portion 21 can be opened. The fracture pressure refers to the pressure at which the notch portion 21 can be broken and opened. Therefore, when the internal pressure of the outer packaging material 12 is lower than the fracture pressure, the notch portion 21 can maintain its shape. When the internal pressure of the outer packaging material 12 rises above the fracture pressure due to the continued use of the battery cell 100, the shape of the notch portion 21 can change. The notch portion 21 can be opened, and the internal gas is discharged to the outside, thereby reducing the internal pressure.

[0068] The notch portion 21 may be broken at a relatively low pressure compared to other regions of the battery cell 100. Thus, damage to the battery cell 100 may be prevented. Regions other than the notch portion 21 of the battery cell 100 may be prevented from breaking.

[0069] However, the notch portion 21 may not be opened smoothly. This is because the stress generated by the expansion of the outer packaging material 12 acts unevenly on the notch portion 21. For example, only a portion of the notch portion 21 may be opened.

[0070] The present disclosure includes a first notch portion 210 and a second notch portion 220 having different thicknesses. Stress concentration in any area can be prevented by making the first notch portion 210 and the second notch portion 220 have different thicknesses. Thus, the notch portion 21 can be opened smoothly, and gas can be effectively discharged.

[0071] Reference Figure 3 The first notch portion 210 and the second notch portion 220 may intersect to form a first intersection point P1 and a second intersection point P2. The first notch portion 210 and the second notch portion 220 may have different thicknesses.

[0072] The thickness of the second notch portion 220 may be thinner than that of the first notch portion 210. The durability of the notch portion 21 may be different depending on the thickness of the notch portion 21. The thinner the thickness of the notch portion 21, the worse its durability may be. Therefore, compared with the first notch portion 210, the second notch portion 220 can be opened under a lower pressure environment.

[0073] Specifically, the first notch portion 210 may be formed extending in one direction within the notch region 20. Figure 3 , the first notch 210 may be formed extending along the Y direction. When the internal pressure of the exterior material 12 rises, only the central portion 211 of the first notch 210 may be broken, and the edge region may not be broken. When the thickness of the second notch 220 is thinner than that of the first notch 210, both the first notch 210 and the second notch 220 may be opened.

[0074] In another embodiment, the first notch portion 210 may be provided in a V-shape within the notch region 20. Figures 9a to 9d The shapes of the first notch portion 210 and the second notch portion 220 will be described in detail.

[0075] The second notch portion 220 may be formed by crossing the first notch portion 210 at one end and the other end of the first notch portion 210. The second notch portion 220 may be formed in a curved manner. The second notch portion 220 may include a first sub-notch portion 221 and a second sub-notch portion 222. The first sub-notch portion 221 may cross one end of the first notch portion 210 to form a first intersection point P1. The second sub-notch portion 222 may cross the other end opposite to one end of the first notch portion 210 to form a second intersection point P2. The first sub-notch portion 221 and the second sub-notch portion 222 may be formed in a curved manner, respectively.

[0076] The first sub-notch portion 221, the second sub-notch portion 222 and the first notch portion 210 may be connected to each other to form. Thus, when any one area of ​​the notch portion 21 is opened, an area of ​​the adjacent notch portion 21 may be smoothly opened by the opening pressure.

[0077] The first sub-notch 221 and the second sub-notch 222 can be formed symmetrically with the first notch 210 as a reference, so that the stress acts evenly on the notch 21, so that the notch can be opened smoothly.

[0078] Figures 4 to 6 Shown along Figure 3 The cross section is taken along the AA' direction.

[0079] Figure 4 2 shows a cross section of the notch portion 21 according to an embodiment of the present disclosure. The thickness of the first notch portion 210 may be thicker than the first intersection portion P1 and the second intersection portion P2. That is, the thickness of the first intersection portion P1 and the second intersection portion P2 may be thinner than the thickness of the first notch portion 210.

[0080] The center portion 211 of the first notch portion may be subjected to concentrated stress. In other words, the center portion 211 of the first notch portion may be opened first. After the center portion 211 of the first notch portion 210 is opened, the two facing sides are opened like cracks in the direction toward the first intersection point P1 and the second intersection point P2.

[0081] By increasing the thickness of the central portion 211 subjected to concentrated stress, the notch portion can be prevented from opening under a pressure below the fracture pressure. In addition, the opening can be guided from the central portion 211 and the notch portion can be completely opened.

[0082] Figure 5 FIG. 2 shows a cross section of a notch portion 21 according to another embodiment of the present disclosure. Figure 5The thickness of the first notch portion 210_1 may be thicker from the first intersection P1 toward the center portion 211_1 formed between the first intersection P1 and the second intersection P2, and may be thinner from the center portion 211_1 toward the second intersection P2. In an embodiment, the thickness L2 at the first intersection and the thickness L2 at the second intersection may be the same. The thickness L1 at the center portion may be thicker than the thickness L2 at the first intersection and the second intersection.

[0083] Figure 6 FIG. 2 shows a cross section of a notch portion 21 according to another embodiment of the present disclosure. The first notch portion 211_2 may include a step. Figure 6 , the first notch portion 211_2 may form a stepped structure, and its thickness increases from the first intersection P1 and the second intersection P2 toward the center. For example, the thickness L1 of the center, the thickness L3 between the center and the second intersection, and the thickness L2 of the second intersection may be different. The thickness may be thinner in the order of the center, between the center and the second intersection, and the second intersection.

[0084] This can improve the durability of the first notch 210. That is, it can prevent the first notch 210 from opening at a pressure lower than the rupture pressure of the exterior material 12.

[0085] Figure 7 FIG. 2 shows a notch portion 21 according to another embodiment of the present disclosure. Figure 8 Shown along Figure 7 The cross section is taken along the BB' direction.

[0086] Reference Figure 7 , the second notch portion 220 may be provided in a shape that is bent at the first intersection P1 and the second intersection P2, respectively. Specifically, the first sub-notch portion 221a may be bent at the first intersection P1, and the second sub-notch portion 222a may be bent at the second intersection P2. Thus, the notch portion 21 may be effectively opened. The second notch portion 220a may be formed closer to the edge of the notch region 20 than the first notch portion 210a.

[0087] The thickness of the first sub-notch portion 221a may be thinner as it is farther from the first intersection P1. The thickness of the second sub-notch portion 222a may be thinner as it is farther from the second intersection P2. The farther the first sub-notch portion 221a is from the first intersection P1, the farther the first sub-notch portion 221a is from the first intersection P1 along the direction in which the first sub-notch portion 221a extends. In addition, the farther the second sub-notch portion 222a is from the second intersection P2, the farther the second sub-notch portion 222a is from the second intersection P2 along the direction in which the second sub-notch portion 222a extends.

[0088] Therefore, the first sub-notch portion 221a and the second sub-notch portion 222a can each form an inclined surface. Figure 8 The thickness L2 at the first intersection P1 may be thicker than the thickness L3 at the other end of the first sub-notch portion 221a. An inclined surface may be formed in which the thickness becomes thinner in a direction from the first intersection P1 toward the other end of the first sub-notch portion 221a.

[0089] Figures 9a to 9d Various embodiments of the notch portion 21 of the present disclosure are shown.

[0090] The shape of the notch 21 is not limited as long as it can be opened when the internal pressure of the outer packaging material 12 increases. Figure 9a The first notch portion 210b may extend across the notch region 20 in a diagonal direction. The second notch portion 220b may be connected to one end and the other end of the first notch portion 210, respectively, and may be formed in a curved manner.

[0091] Reference Figure 9b The first notch portion 210c may be provided in a V-shape within the notch region 20. The first sub-notch portion 221c may be connected to one end of the first notch portion 210c, and the second sub-notch portion 222c may be connected to the other end of the first notch portion.

[0092] In addition, refer to Fig.9c , the second notch portion 220d may be provided in a linear shape. The first sub-notch portion 221d and the second sub-notch portion 222d may be provided in a linear shape, respectively. An intersection may be formed in the central area of ​​the first sub-notch portion 221d, and an intersection may be formed in the central area of ​​the second sub-notch portion 222d. In addition, referring to Figure 9d , the first notch portion 210e and the second notch portion 220e may be connected to each other to form a U shape.

[0093] The present disclosure can be implemented in various forms, and the scope of the rights of the present disclosure is not limited by the above-mentioned embodiments. Therefore, if the modified embodiments include the elements in the claims of the present disclosure, they should be deemed to belong to the scope of the rights of the present disclosure.

Claims

1. A battery cell, comprising: An electrode assembly, including a positive electrode, a negative electrode and a separator; as well as an outer packaging material, wherein the electrode assembly is accommodated inside the outer packaging material, and a notch portion is provided in a preset notch area of ​​the outer packaging material, The notch portion comprises: The first notch portion has a preset thickness; as well as The second notch portion intersects one end of the first notch portion to form a first intersection, and intersects the other end opposite to the one end of the first notch portion to form a second intersection, and the thickness of the second notch portion is different from the thickness of the first notch portion.

2. The battery cell according to claim 1, wherein: The second notch portion has a thickness thinner than that of the first notch portion.

3. The battery cell according to claim 1, wherein: The thickness of the first notch portion increases from the first intersection toward a center portion formed between the first intersection and the second intersection, and decreases from the center portion toward the second intersection.

4. The battery cell according to claim 1, wherein: The first notch portion includes a step.

5. The battery cell according to claim 3, wherein: The first notch portion is formed extending along one direction in the notch region.

6. The battery cell according to claim 1, wherein: The first notch portion is provided in a V shape in the notch region.

7. The battery cell according to claim 1, wherein: The two notch portions include a first sub-notch portion forming the first intersection and a second sub-notch portion forming the second intersection, The thickness of the first sub-notch portion becomes thinner as it is farther from the first intersection, and the thickness of the second sub-notch portion becomes thinner as it is farther from the second intersection.

8. The battery cell according to claim 7, wherein: The first sub-notch portion and the second sub-notch portion are formed symmetrically with respect to the first notch portion.

9. The battery cell according to claim 1, wherein: The second notch portion is formed in a curved manner.

10. The battery cell according to claim 1, wherein: The second notch portion has a shape bent at the first intersection and the second intersection, respectively.

11. The battery cell according to claim 1, wherein: The second notch portion is formed closer to an edge of the notch region than the first notch portion.

12. The battery cell according to claim 1, wherein: The first notch portion and the second notch portion are connected to each other to form a U shape.

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