Secondary battery

Abstract

Embodiments of the present invention relate to a secondary battery, and the technical problem to be solved is to provide a secondary battery with excellent stability. To this end, a secondary battery is disclosed, which includes: an electrode assembly; a can that houses the electrode assembly and an electrolyte and has a curled portion formed above the electrode assembly; a cover assembly for sealing the can; and an adsorption member disposed in a space including at least the gap between the electrode assembly and the curled portion and reacting with the electrolyte after a specific period of time after contacting the electrolyte, thereby adsorbing the electrolyte.

Description

Technical Field

[0001] Embodiments of the present invention relate to a secondary battery. Background Art

[0002] Unlike non-rechargeable primary batteries, secondary batteries refer to batteries that can be recharged and discharged. Low-capacity secondary batteries are mainly used in portable small electronic devices such as smartphones, laptop computers, digital cameras, and video cameras, and high-capacity secondary batteries are widely used for motor drive and power storage in hybrid vehicles, electric vehicles, etc. Therefore, secondary batteries need to have characteristics such as high density, high output, and stability.

[0003] The above information disclosed in this background art section is only for enhancing the understanding of the background art of the invention, and thus may include information that does not constitute the prior art. Summary of the Invention

[0004] Technical Problem

[0005] Embodiments of the present invention provide a secondary battery having excellent stability.

[0006] Technical Solution

[0007] The secondary battery according to an embodiment of the present invention may include: an electrode assembly; a can that houses the electrode assembly and an electrolyte and has a curled portion formed above the electrode assembly; a cover assembly for sealing the can; and an adsorption member disposed in a space including at least a gap between the electrode assembly and the curled portion and reacting with the electrolyte after a specific period of time after contacting the electrolyte, thereby adsorbing the electrolyte.

[0008] In addition, the adsorption member is at least made of a material including an acrylic binder, oriented polystyrene (OPS), or polyvinylidene fluoride (PVdF).

[0009] In addition, the secondary battery may further include an insulating member made of a material that does not react with the electrolyte and disposed between the electrode assembly and the adsorption member.

[0010] In addition, the insulating member may be formed in the form of a film.

[0011] In addition, the adsorption member and the insulating member may be combined with each other.

[0012] In addition, the adsorption member may be formed in a shape corresponding to the curled portion.

[0013] In addition, the adsorption member may be formed in the form of a sheet, and its edge may be bent upward.

[0014] Advantageous Effects

[0015] Embodiments of the invention provide a secondary battery that can prevent corrosion of the crimped portion and solve low voltage performance by allowing an adsorption member to adsorb an electrolyte even if the negative electrode expands due to charging after the assembly of the secondary battery is completed and the electrolyte is partially pushed into an isolated gap under the crimped portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a perspective view of a secondary battery according to an embodiment of the present invention.

[0017] Figure 2 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

[0018] Figure 3 is Figure 2 an enlarged view of part III in

[0019] Figure 4 is a cross-sectional view of a secondary battery according to another embodiment of the present invention, showing an enlarged view of a part corresponding to part III in Figure 2

[0020] Figure 5 is a cross-sectional view of a secondary battery according to still another embodiment of the present invention, showing an enlarged view of a part corresponding to part III in Figure 2

[0021] Figure 6 is a cross-sectional view of a secondary battery according to still another embodiment of the present invention, showing an enlarged view of a part corresponding to part III in Figure 2 DETAILED DESCRIPTION

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0023] Examples of the present invention are provided to more fully explain the present invention to those skilled in the art, and the following examples can be modified in various other forms. However, the present invention can be implemented in many different forms and should not be construed as limited to the example (or exemplary) embodiments set forth herein. On the contrary, these example embodiments are provided so that this disclosure will be thorough and complete and will convey the aspects and features of the present invention to those skilled in the art.

[0024] In addition, in the drawings, for the sake of simplicity and clarity, the sizes or thicknesses of various components are exaggerated. The same reference numerals always refer to the same elements. As used herein, the term "and / or" includes any combination and all combinations of one or more of the related listed items. Additionally, it will be understood that when an element A is referred to as being "connected to" an element B, element A can be directly connected to element B, or there can be an intervening element C therebetween such that element A and element B are indirectly connected to each other.

[0025] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. It will also be understood that when the terms "comprises" and / or its variants are used in this specification, they specify the presence of the stated features, numbers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and / or groups thereof.

[0026] It will be understood that although the terms "first", "second", etc. may be used herein to describe various members, elements, regions, layers, and / or parts, these members, elements, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one member, element, region, layer, and / or part from another member, element, region, layer, and / or part. Thus, for example, without departing from the teachings of the present invention, the first member, first element, first region, first layer, and / or first part discussed below may be referred to as the second member, second element, second region, second layer, and / or second part.

[0027] For ease of description, spatial relative terms such as "beneath", "below", "under", "above", "on", etc. may be used herein to describe the relationship of one element or feature to another (other) element or feature as shown in the figures. It will be understood that in addition to covering the orientations depicted in the figures, the spatial relative terms are also intended to cover different orientations of the device in use or operation. For example, if the element or feature in the figure is flipped, the element described as being "beneath" or "under" other elements or features will subsequently be positioned "above" or "on" the said other elements or features. Thus, the exemplary term "beneath" can cover both the upper and lower orientations.

[0028] Figure 1 is a perspective view of a secondary battery 100 according to an embodiment of the present invention, Figure 2 is a cross-sectional view of a secondary battery 100 according to an embodiment of the present invention, Figure 3 is Figure 2 an enlarged view of part III in

[0029] Reference Figures 1 to 3 Figures 1 to 3 , the secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 110, a can 120, a cap assembly 130, and an adsorption member 140.

[0030] The electrode assembly 110 may include a first electrode 111, a second electrode 112, and a separator 113, and may be wound into a so-called jelly-roll shape.

[0031] The first electrode 111 has a first coated portion formed by applying and roll-coating a first active material onto a first substrate and a first uncoated portion where the first active material is not applied. In addition, a first tab 111A may be drawn upward from the first uncoated portion and may be electrically connected to the cap assembly 130 to be described later. The first electrode 111 may serve as a positive electrode. In this case, the first substrate may be made of, for example, aluminum foil, and the first active material may be made of, for example, a transition metal oxide.

[0032] The second electrode 112 has a second coated portion formed by applying and roll-coating a second active material onto a second substrate and a second uncoated portion where the second active material is not applied. In addition, a second tab 112A may be drawn upward from the second uncoated portion and may be electrically connected to the can 120 to be described later. The second electrode 112 may serve as a negative electrode. In this case, the second substrate may be made of, for example, copper foil or nickel foil, and the second active material may be made of, for example, graphite.

[0033] The separator 113 is disposed between the first electrode 111 and the second electrode 112 to prevent a short circuit between the first electrode 111 and the second electrode 112 while allowing the movement of lithium ions. The separator 113 may be made of, for example, a polyethylene film, a polypropylene film, or a composite film of polyethylene and polypropylene.

[0034] The can 120 houses the electrode assembly 110 and the electrolyte. In the drawings, the can 120 is shown to be generally formed in a cylindrical shape, but the technical concept of the present invention is not necessarily limited to a cylindrical secondary battery. However, hereinafter, for convenience, a cylindrical secondary battery will be described as an example.

[0035] The can 120 has an open upper surface in the initial stage. Therefore, after the electrode assembly 110 is installed in the can 120 through the upper surface and the electrolyte is injected, a crimped portion 121 for preventing the movement of the electrode assembly 110 is formed. Then, after the cap assembly 130 is installed on the crimped portion 121, a caulked portion 122 for fixing the cap assembly 130 may be formed and completed.

[0036] The can 120 may be made of, for example, nickel-plated iron.

[0037] In addition, the electrolyte may include, for example, an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), or ethyl methyl carbonate (EMC), and a lithium salt such as LiPF6 or LiBF4.

[0038] The lid assembly 130 is used to seal the can 120 and includes an upper lid 131, a safety vent 132, a lower lid 133, and an insulator 134.

[0039] The upper lid 131 protrudes upwardly and has a terminal portion 131A for connection to an external circuit and an outlet 131B formed around the terminal portion 131A for discharging gas.

[0040] The safety vent 132 is provided below the upper lid 131. Additionally, the safety vent 132 has a protrusion 132A that protrudes downwardly and is electrically connected to the first tab 111A, and a notch 132B. When gas is generated inside the safety vent 132 due to overcharging or abnormal operation of the secondary battery 100, the protrusion 132A deforms upwardly due to the pressure and separates from the first tab 111A while being cut along the notch 132B, allowing the gas to be discharged, thereby preventing the explosion of the secondary battery 100.

[0041] The lower lid 133 is provided below the safety vent 132. Further, as described above, the lower lid 133 has a through hole 133B in which the protrusion 132A of the safety vent 132 is positioned, and an outlet 133A for discharging gas when gas is generated therein.

[0042] The insulator 134 is provided between the safety vent 132 and the lower lid 133 to insulate the safety vent 132 and the lower lid 133 from each other.

[0043] Generally, in the secondary battery 100, as described above, after the electrode assembly 110 is installed in the can 120 and the electrolyte is injected, a crimped portion 121 is formed, and after the lid assembly 130 is installed on the crimped portion 121, the crimped portion 121 can be pressed by pressure during the process of forming the caulked portion 122, so that an isolated gap V can be generated below the crimped portion 121.

[0044] Therefore, when the second electrode (i.e., the negative electrode) 112 expands due to charging, the electrolyte is partially pushed into the corresponding gap V and contacts the crimped portion 121. In other words, the electrode assembly 110 and the crimped portion 121 may be connected to each other through the electrolyte. At this time, the crimped portion 121 is in a state where the nickel plating is slightly fragile due to the stress caused by molding, so it is easily corroded, causing nickel ions to deposit on the second electrode 112. This ultimately leads to the problem of low voltage performance.

[0045] To solve this problem, an adsorption member 140 may be disposed in a region including at least a part between the electrode assembly 110 and the crimped portion 121. In the drawings, the adsorption member 140 is formed in a plate shape and is shown to be completely disposed on the electrode assembly 110.

[0046] Specifically, the adsorption member 140 may adsorb the electrolyte by reacting with the electrolyte after a specific time after contacting the electrolyte. In other words, the adsorption member 140 does not immediately react with the electrolyte injected when assembling the secondary battery 100, but reacts with the electrolyte released in the void V later and then adsorbs the electrolyte.

[0047] Therefore, even after the assembly of the secondary battery 100 is completed and the negative electrode expands due to charging and the electrolyte is partially pushed into the void V, the adsorption member 140 adsorbs the electrolyte, thereby preventing the crimped portion 121 from being corroded.

[0048] The adsorption member 140 may be formed of, for example, an acrylic adhesive, oriented polystyrene (OPS), polyvinylidene fluoride (PVdF), or a combination thereof.

[0049] In addition, considering the general dimensions of the cylindrical secondary battery, the average amount of the electrolyte to be released, etc., the adsorption member 140 may be formed to have a thickness of about 0.3 mm to about 0.6 mm in order to adsorb about 0.05 g to about 0.1 g of the electrolyte.

[0050] Table 1 below shows the results of placing an acrylic adhesive film (sample) having a thickness of 40 μm in the electrolyte and measuring the total weight over a specific time.

[0051] [Table 1]

[0052]

[0053] (Unit: mg) From the results of 12 experiments at room temperature and high temperature respectively, it can be seen that the weight increases after about 1 hour to 2 hours of placing the sample in the electrolyte, and then the weight remains almost constant thereafter.

[0054] This shows that the adsorption member 140 does not immediately react with the electrolyte injected when assembling the secondary battery 100, but reacts sufficiently with the electrolyte released in the void V later, thereby effectively adsorbing the electrolyte.

[0055] Figure 4 is a cross-sectional view of a secondary battery 200 according to another embodiment of the present invention, showing an enlarged view of a part corresponding to part III in Figure 2 The enlarged view of the corresponding part of the part III.

[0056] Refer to Figure 4The secondary battery 200 according to another embodiment of the present invention is similar to the one already mentioned above. Figures 1 to 3 The secondary battery 100 according to the embodiment of the present invention is described to be different in that the former further includes an insulating member 250 .

[0057] The insulating member 250 is made of, for example, polypropylene (PP) or other polymers that do not react with the electrolyte, and is disposed between the electrode assembly 110 and the adsorption member 240 .

[0058] Therefore, the lower side of the adsorption member 240 is protected by the insulating member 250 and does not contact the electrolyte injected when assembling the secondary battery 200, thus having an advantage that the electrolyte to be released later can be more effectively adsorbed without affecting the electrolyte impregnation during assembly.

[0059] The insulating member 250 may be formed in the form of a sheet having a thickness of, for example, about 0.2 mm. In this case, considering the overall size of the cylindrical secondary battery 200 and the average amount of electrolyte to be released, the adsorption member 240 may be formed to a thickness of about 0.2 mm to about 0.4 mm to adsorb about 0.05 g to about 0.1 g of electrolyte.

[0060] Alternatively, the insulating member 250 may be formed in the form of a film having a thickness of, for example, about 0.05 mm or less. Therefore, the thickness of the adsorption member 240 may be increased as much as the thickness of the insulating member 250 is reduced, so there is an advantage in that the electrolyte to be released later can be more effectively absorbed. In this case, the adsorption member 240 may be formed to a thickness of about 0.3 mm to about 0.6 mm to adsorb about 0.05 g to about 0.1 g of electrolyte.

[0061] In addition, the adsorption member 240 and the insulation member 250 may be combined with each other by, for example, a double-sided tape, and may be integrally mounted in the can 120 during assembly.

[0062] Alternatively, the adsorption member 240 and the insulating member 250 may be separately installed in the can 120 during assembly. For example, the insulating member 250 may be first installed on the electrode assembly 110, and the adsorption member 240 may be further installed on the insulating member 250.

[0063] In the secondary battery 200 according to another embodiment of the present invention, other matters are the same as those already mentioned above. Figures 1 to 3 Matters in the secondary battery 100 according to the embodiment of the present invention described are substantially the same, or to the extent that those skilled in the art would naturally expect changes from the foregoing description, redundant descriptions thereof will be omitted.

[0064] Figure 5is a cross-sectional view of a secondary battery 300 according to another embodiment of the present invention, showing Figure 2 An enlarged view of the portion corresponding to section III.

[0065] Reference Figure 5 According to another embodiment of the present invention, the secondary battery 300 is similar to the one already mentioned above. Figures 1 to 3 The secondary battery 100 according to the embodiment of the present invention is described differently in that the adsorption member 340 is formed in a shape corresponding to the lower portion of the beading portion 121. For example, the adsorption member 340 is formed such that its edge slightly convexly protrudes upward to fill the void V.

[0066] To this end, the adsorption member 340 may be formed by applying a shape associated with injection molding, or the shape thereof may be realized by cutting a remaining area of the adsorption member 340 .

[0067] In the secondary battery 300 according to another embodiment of the present invention, other matters are the same as those already mentioned above. Figures 1 to 3 Matters in the secondary battery 100 according to the embodiment of the present invention described are substantially the same, or to the extent that those skilled in the art would naturally expect changes from the foregoing description, redundant descriptions thereof will be omitted.

[0068] Figure 6 is a cross-sectional view of a secondary battery 400 according to another embodiment of the present invention, showing Figure 2 An enlarged view of the portion corresponding to section III.

[0069] Reference Figure 6 The secondary battery 400 according to still another embodiment of the present invention is the same as the secondary battery 300 according to still another embodiment of the present invention in that the adsorption member 440 is formed in a shape corresponding to the lower portion of the curling portion 121, but the way of realizing the shape is different.

[0070] More specifically, the adsorption member 440 is formed as a thin sheet, and an edge thereof is bent upward to be shaped to fill the void (V).

[0071] In the secondary battery 400 according to another embodiment of the present invention, other matters are the same as those already mentioned above. Figure 5 Other matters in the secondary battery 300 according to the embodiment of the present invention described are substantially the same, or to the extent that those skilled in the art would naturally expect changes from the foregoing description, redundant descriptions thereof will be omitted.

[0072] Although the foregoing embodiments for implementing the secondary batteries 100, 200, 300, and 400 according to the present invention have been provided, it should be understood that the embodiments described herein should be considered merely descriptive and not for purposes of limitation, and that various changes in form and detail may be made therein without departing from the spirit and scope of the disclosure defined by the appended claims.

Claims

1. A secondary battery, the secondary battery comprising: An electrode assembly; A can that houses the electrode assembly and an electrolyte and has a curled edge portion formed above the electrode assembly and having a separated gap (V) therebetween; A lid assembly for sealing the can; An adsorption member disposed in a space including at least the gap (V) and reacting with the electrolyte released in the gap (V) after a specific period of time after contacting the electrolyte, thereby adsorbing the electrolyte released in the gap (V); And An insulating member made of a material that does not react with the electrolyte and directly mounted on the electrode assembly between the electrode assembly and the adsorption member.

2. The secondary battery according to claim 1, wherein The adsorption member is made of at least a material containing an acrylic binder, oriented polystyrene, or polyvinylidene fluoride.

3. The secondary battery according to claim 1, wherein The insulating member is formed in the form of a film.

4. The secondary battery according to claim 1, wherein, The adsorption member and the insulating member are bonded to each other.

5. The secondary battery according to claim 1, wherein, The adsorption member is formed in a shape corresponding to the curled edge portion.

6. The secondary battery according to claim 1, wherein, The adsorption member is formed in the form of a sheet, and the edge of the adsorption member is bent upward.

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