Electrode assembly with coating for preventing short circuit

Abstract

The present invention relates to an electrode assembly including a short-circuit prevention coating, and more particularly, to an electrode assembly including: a positive electrode sheet having a positive electrode tab protruding from one outer end thereof, and a positive electrode mixture layer including a positive electrode active material coated on a lower portion of the positive electrode tab and a current collector; a negative electrode sheet having a negative electrode tab protruding from one outer end thereof, and a negative electrode mixture layer including a negative electrode active material coated on a lower portion of the negative electrode tab and a current collector; and a separator positioned between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet has a shoulder portion extending horizontally by a predetermined length and coated with the negative electrode active material, and the shoulder portion is surrounded by a coating.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 2021-0109580 filed on August 19, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly having a coating for preventing short circuits, and more particularly to an electrode assembly having a coating for preventing short circuits formed on a part of a negative electrode sheet, thereby improving safety by preventing a short circuit that may occur due to contact between a positive electrode mixture layer formed on a positive electrode tab and a negative electrode sheet. [Background technology]

[0003] Recently, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. Secondary batteries are also attracting attention as energy sources for electric vehicles and hybrid electric vehicles, which have been presented as a solution to address air pollution caused by existing gasoline and diesel vehicles that use fossil fuels. Therefore, the types of applications in which secondary batteries are used are becoming increasingly diverse due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to many more fields and products in the future.

[0004] Such secondary batteries may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc., depending on the configuration of the electrodes and electrolyte. Among them, the use of lithium ion polymer batteries, which have a low possibility of electrolyte leakage and are easy to manufacture, is increasing. In general, secondary batteries are classified into cylindrical batteries and prismatic batteries, in which an electrode assembly is housed in a cylindrical or prismatic metal can, and pouch batteries, in which an electrode assembly is housed in a pouch-type case made of an aluminum laminate sheet, depending on the shape of the battery case.

[0005] The electrode assembly built into the battery case is a chargeable and dischargeable power generating element having a structure including a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. The electrode assembly is classified into a jelly roll type in which a long sheet-like positive electrode and a negative electrode coated with an active material are wound with a separator interposed between them, and a stack type in which a number of positive electrodes and negative electrodes having a predetermined size are stacked in sequence with a separator interposed between them.

[0006] FIG. 1 is a perspective view showing an electrode plate according to the prior art.

[0007] Referring to FIG. 1, a conventional electrode plate includes an electrode current collector 10 , an electrode active material layer 20 , and an electrode tab 30 .

[0008] The electrode tab 30 may include an extended region 31, an inclined portion 32, and a plain portion 33, and an electrode mixture layer containing an electrode active material is applied to the extended region 31 and the inclined portion 32.

[0009] The electrode tab 30 according to the conventional art has a problem in that the separator may shrink due to heat during a lamination process in which heat is applied during the process of manufacturing an electrode assembly, and therefore, the uncoated portion 33 or the extension region 31 and the inclined portion 32 may come into contact with the nearby electrode plate, causing a short circuit.

[0010] In addition, since the extension region 31 and the inclined portion 32 are formed on the electrode tab 30, there is a problem that an overhang inversion phenomenon may occur in which the capacity ratio (N / P ratio) of the negative electrode to the positive electrode is reversed depending on the characteristics of the mixture layer formation. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Korean Patent Publication No. 2011-0060036 Summary of the Invention [Problem to be solved by the invention]

[0012] In order to solve the above problems, an object of the present invention is to provide an electrode assembly having an anti-short circuit coating that can prevent contact between a positive electrode tab and a negative electrode sheet that is located on the same vertical line as a positive electrode mixture layer formed under the positive electrode tab.

[0013] In addition, the electrode assembly with an anti-short circuit coating according to the present invention has a shoulder portion extending a predetermined length from the negative electrode sheet on the same vertical line as the positive electrode mixture layer formed under the positive electrode tab, thereby suppressing the occurrence of an overhang inversion phenomenon, thereby providing an electrode assembly with an anti-short circuit coating that can prevent lithium precipitation. [Means for solving the problem]

[0014] In order to achieve the above object, the electrode assembly with a coating portion for preventing short circuit according to the present invention includes a positive electrode sheet (100) having a positive electrode tab (110) protruding from one outer end and a positive electrode mixture layer (120) containing a positive electrode active material coated on the underside of the positive electrode tab (110) and on a current collector, a negative electrode sheet (200) having a negative electrode tab (210) protruding from one outer end and a negative electrode mixture layer (220) containing a negative electrode active material coated on the underside of the negative electrode tab (210) and on a current collector, and a separator (300) located between the positive electrode sheet (100) and the negative electrode sheet (200), wherein the negative electrode sheet (200) has a shoulder portion (230) extending horizontally by a predetermined length and coated with the negative electrode active material, and the shoulder portion (230) is surrounded by a coating portion (400).

[0015] In addition, in the electrode assembly according to the present invention, the coating portion (400) includes a pair of horizontal portions (410) arranged in parallel, and a vertical portion (420) connecting one side ends of the pair of horizontal portions (410).

[0016] In the electrode assembly according to the present invention, the coating portion (400) is made of an insulating material.

[0017] In the electrode assembly according to the present invention, the shoulder portion (230) is formed on a vertical extension of the positive electrode tab (110).

[0018] In the electrode assembly according to the present invention, the width (W1) of the shoulder portion (230) is larger than the width (W2) of the positive electrode tab.

[0019] The present invention may also be a battery cell including the electrode assembly.

[0020] The present invention may also be a battery pack including one or more of the battery cells.

[0021] In addition, a method for manufacturing an electrode assembly according to the present invention includes the steps of preparing a positive electrode sheet, a negative electrode sheet, and a separator; notching the negative electrode sheet to form a shoulder portion; forming a coating portion on the shoulder portion; and stacking the positive electrode sheet, the separator, and the negative electrode sheet.

[0022] In the method for manufacturing an electrode assembly according to the present invention, the step of stacking the positive electrode sheet, the separator, and the negative electrode sheet may be performed such that a center line of the shoulder portion and a center line of the positive electrode tab are aligned on the same line.

[0023] In the method for manufacturing an electrode assembly according to the present invention, the electrode assembly may have a stack type, a zigzag type, or a stack / folding type structure.

[0024] In addition, in the manufacturing method of the electrode assembly according to the present invention, the electrode assembly is formed from a unit cell such as a single electrode plate, a bi-cell in which electrodes on both outer sides have the same polarity, or a full cell in which electrodes on both outer sides have opposite polarities. Effect of the Invention

[0025] As described above, the electrode assembly having an anti-short circuit coating according to the present invention has an advantage in that the coating is provided between the positive electrode mixture layer formed on the positive electrode tab and the shoulder portion of the negative electrode sheet to prevent contact therebetween, thereby improving safety.

[0026] In addition, the electrode assembly having an anti-short circuit coating according to the present invention has an advantage in that a shoulder portion extending a predetermined length is formed on a vertical line of a positive electrode mixture layer formed on a positive electrode tab, thereby suppressing an overhang inversion phenomenon and preventing lithium precipitation. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a perspective view showing an electrode plate according to the prior art. [Diagram 2] 1 is a perspective view of an electrode assembly according to a preferred embodiment of the present invention; [Diagram 3] 3 is a cross-sectional view of the electrode assembly shown in FIG. 2 taken along line AA'. [Figure 4] 2 is a plan view showing a positive electrode sheet and a negative electrode sheet excluding a separator in an electrode assembly according to a preferred embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, in which a person having ordinary skill in the art to which the present invention pertains can easily carry out the present invention. However, in describing the operation principle of the preferred embodiment of the present invention in detail, detailed description of related well-known functions or configurations will be omitted if it is determined that such detailed description may unnecessarily obscure the gist of the present invention.

[0029] In addition, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where the part is directly connected to another part, but also the case where the part is indirectly connected via another element between the two parts. In addition, when a part includes a certain component, it does not mean that the other component is excluded, but that the part may further include the other component, unless otherwise specified.

[0030] Hereinafter, an electrode assembly having a coating for preventing short circuits according to the present invention will be described with reference to the accompanying drawings.

[0031] FIG. 2 is a perspective view of an electrode assembly according to a preferred embodiment of the present invention, FIG. 3 is a cross-sectional view of the electrode assembly shown in FIG. 2 taken along line A-A', and FIG. 4 is a plan view of a positive electrode sheet and a negative electrode sheet excluding a separator in an electrode assembly according to a preferred embodiment of the present invention.

[0032] 2 to 4, an electrode assembly according to a preferred embodiment of the present invention includes a positive electrode sheet 100, a negative electrode sheet 200, a separator 300, and a coating unit 400. As shown in FIG.

[0033] The positive electrode sheet 100 has a positive electrode tab 110 protruding from one outer peripheral end by a predetermined length, and a positive electrode mixture layer 120 containing a positive electrode active material is applied to the bottom of the positive electrode tab 110 protruding by a predetermined length and on the current collector.

[0034] In FIG. 3, the positive electrode mixture layer 120 applied to the lower part of the positive electrode tab 110 is shown as having a right-angled shape, but the positive electrode mixture layer 120 applied to the lower part of the positive electrode tab 110 may have a slide shape having a predetermined curvature or an inclined surface at a predetermined angle.

[0035] In the negative electrode sheet 200, a negative electrode tab 210 protrudes a predetermined length from one outer peripheral end, and a negative electrode mixture layer 220 containing a negative electrode active material is applied to the bottom of the negative electrode tab 210 protruding a predetermined length and on the current collector.

[0036] Here, the negative electrode sheet 200 has a relatively larger area than the positive electrode sheet 100. This is to prevent the occurrence of an overhang inversion phenomenon.

[0037] In addition, the negative electrode sheet 200 has a shoulder portion 230 extending a predetermined length at a portion that overlaps with a portion of the positive electrode sheet 100 where the positive electrode tab 110 is to be formed when the electrode assembly is formed.

[0038] That is, the shoulder portion 230 may be formed on the negative electrode sheet 200 located on a vertical extension line of the positive electrode tab 110, and may be formed by extending a predetermined length in a state where the negative electrode mixture layer 220 is applied at a portion of the negative electrode sheet 200 corresponding to the lower portion of the positive electrode tab 110 on which the positive electrode mixture layer 120 is applied. This has the advantage of being able to suppress the occurrence of an overhang inversion phenomenon.

[0039] When the negative electrode sheet 200 is formed, a negative electrode mixture layer 220 containing a negative electrode active material is applied to the shoulder portion 230 .

[0040] In addition, the width W1 of the shoulder portion 230 is formed to be larger than the width W2 of the positive electrode tab 110 by a predetermined size. This has the advantage of preventing lithium deposition by suppressing the occurrence of an overhang inversion phenomenon due to the positive electrode mixture layer 120 formed under the positive electrode tab 110, thereby improving safety.

[0041] In addition, the shoulder portion 230 has a rectangular shape in a plan view, and the protruding length of the shoulder portion 230 may be longer than the positive electrode mixture layer 120 applied to the lower portion of the positive electrode tab 110 .

[0042] Next, the separator 300 is located between the positive electrode sheet 100 and the negative electrode sheet 200 and serves to prevent a short between the positive electrode sheet 100 and the negative electrode sheet 200 and to allow only the movement of lithium ions. The separator 300 is preferably any one selected from polyethylene, polypropylene, a polyethylene / polypropylene double layer, a polyethylene / polypropylene / polyethylene triple layer, a polypropylene / polyethylene / polypropylene triple layer, and an organic fiber filter paper, but is not limited thereto.

[0043] The coating unit 400 includes a pair of horizontal portions 410 arranged side by side with a predetermined distance between them, and a vertical portion 420 connecting one side ends of the pair of horizontal portions 410 .

[0044] The coating portion 400 is positioned to surround the shoulder portion 230 and serves to prevent short circuits.

[0045] For example, after a lamination process in which heat is applied during the manufacture of an electrode assembly, the separator may shrink due to heat, causing the positive electrode tab 110 and the shoulder portion 230 to come into contact with each other, resulting in a short circuit.

[0046] Here, since the coating portion 400 is positioned to surround the shoulder portion 230, there is an advantage in that the positive electrode tab 110 and the shoulder portion 230 can be prevented from coming into contact with each other, resulting in a short circuit.

[0047] The coating portion 400 is made of an insulating material, which may be one of rubber and silicone materials, but is not limited to these, as long as it is a material that can be positioned to surround the shoulder portion 230 and maintain an insulating state.

[0048] The present invention may be a battery cell including an electrode assembly having one or more of the features described above.

[0049] The present invention may be a battery pack including one or more of the battery cells described above.

[0050] A method for manufacturing an electrode assembly according to a preferred embodiment of the present invention includes the steps of preparing a positive electrode sheet 100, a negative electrode sheet 200, and a separator 300, notching the negative electrode sheet 200 to form a shoulder portion 230, forming a coating portion 400 on the shoulder portion 230, and stacking the positive electrode sheet 100, the separator 300, and the negative electrode sheet 200.

[0051] The step of preparing the positive electrode sheet, the negative electrode sheet, and the separator is a step of forming the positive electrode sheet and the negative electrode sheet by applying a mixture layer containing an electrode active material to a current collector, and preparing a separator that prevents a short circuit between the positive electrode sheet and the negative electrode sheet.

[0052] The step of notching the negative electrode sheet 200 to form the shoulder portion 230 is a step of notching the negative electrode sheet 200, in which the negative electrode mixture layer 220 containing the negative electrode active material is applied to the current collector, to form the negative electrode tab 210 and the shoulder portion 230 located a predetermined distance away from the negative electrode tab 210.

[0053] Here, the positive electrode sheet 100 may be notched to form a positive electrode tab 110, and a positive electrode mixture layer 120 may be applied to the lower end of the positive electrode tab 110.

[0054] The step of forming the coating portion 400 on the shoulder portion 230 may prevent a short circuit from occurring due to contact with the positive electrode tab 110 by surrounding the shoulder portion 230 formed by notching with the coating portion 400 made of an insulating material.

[0055] The step of stacking the positive electrode sheet 100, the separator 300, and the negative electrode sheet 200 is a step of stacking the positive electrode sheet 100, the separator 300, and the negative electrode sheet 200 to form an electrode assembly.

[0056] Here, the negative electrode sheet 200 is laminated such that the center line of the shoulder portion 230 and the center line of the positive electrode tab 110 are aligned on the same line. This is because if the shoulder portion 230 and the positive electrode tab 110 are laminated with a misalignment, an overhang inversion phenomenon may occur.

[0057] The electrode assembly manufactured by the manufacturing method of the electrode assembly according to the present invention may have a stack type, a zigzag type, or a stack / folding type structure.

[0058] Here, the electrode assembly according to the present invention may be, but is not limited to, a jelly roll type cell assembly having a structure in which a separator is interposed between long sheet-like positive and negative electrodes and then wound up, a stack type cell assembly composed of unit cells having a structure in which rectangular positive and negative electrodes are stacked with a separator interposed therebetween, a stack folding type cell assembly in which unit cells are wound up with a long separator film, or a lamination stack type cell assembly in which unit cells are stacked with a separator interposed therebetween and attached to each other.

[0059] Next, the sheet separation film forms a stack / fold type electrode assembly having a structure in which a plurality of unit cells are wound up, and the outermost separation film located on a vertical extension line of the sliding portion of the electrode located at the outermost edge of the separation film is curved with the same curvature as the sliding portion and adheres closely to the electrode, which has the advantage that it is possible to prevent the occurrence of a precipitation phenomenon caused by the occurrence of diffusion resistance in the space between the sliding portion of the outermost electrode and the separation film in the electrode assembly according to the conventional technology.

[0060] In addition, the electrode assembly manufactured by the manufacturing method of the electrode assembly according to the present invention may be composed of a unit cell such as a single electrode plate, a bi-cell in which the electrodes on both outer surfaces have the same polarity, or a full cell in which the electrodes on both outer surfaces have opposite polarities.

[0061] Here, the bicell may be an A-type bicell in which a positive electrode, a negative electrode, and a positive electrode are stacked in order with a separator between them, or a C-type bicell in which a negative electrode, a positive electrode, and a negative electrode are stacked in order with a separator between them.

[0062] Those skilled in the art will appreciate that various applications and modifications within the scope of the present invention are possible based on the above content. [Explanation of symbols]

[0063] 100 Positive electrode sheet 110 Positive tab 120 Positive electrode mixture layer 200 Negative electrode sheet 210 Negative electrode tab 220 Negative electrode mixture layer 230 Shoulder section 300 Separation membrane 400 Coating Section 410 Horizontal part 420 Vertical section W1 Shoulder width W2 Positive tab width

Claims

1. a positive electrode sheet having a positive electrode tab protruding from one outer end thereof and a positive electrode mixture layer including a positive electrode active material coated on a lower portion of the positive electrode tab and on a current collector; a negative electrode sheet having a negative electrode tab protruding from one outer end thereof and a negative electrode mixture layer including a negative electrode active material coated on a lower portion of the negative electrode tab and on a current collector; a separator located between the positive electrode sheet and the negative electrode sheet; The negative electrode sheet has a larger area than the positive electrode sheet, The negative electrode sheet has a shoulder portion extending horizontally by a predetermined length and coated with the negative electrode active material, the shoulder portion is formed on a vertical extension line of the positive electrode tab, The protruding length of the shoulder portion is longer than the positive electrode mixture layer applied to the lower portion of the positive electrode tab, The shoulder portion is surrounded by a coating of insulating material.

2. The electrode assembly of claim 1 , wherein the coating portion includes a pair of horizontal portions arranged side by side, and a vertical portion connecting one side ends of the pair of horizontal portions.

3. The electrode assembly of claim 1 , wherein the width of the shoulder portion is greater than the width of the positive electrode tab.

4. A battery cell comprising the electrode assembly according to any one of claims 1 to 3.

5. A battery pack comprising one or more battery cells according to claim 4.

6. Preparing a positive electrode sheet, a negative electrode sheet, and a separator; notching the negative electrode sheet to form a shoulder portion; forming a coating portion of an insulating material on the shoulder portion; The method of claim 1 , further comprising: laminating the positive electrode sheet, the separator, and the negative electrode sheet.

7. 7. The method of claim 6, wherein the positive electrode sheet, the separator, and the negative electrode sheet are stacked such that a center line of the shoulder portion and a center line of the positive electrode tab are aligned on the same line.

8. The method of claim 6, wherein the electrode assembly has a stacked, zigzag or stack / folded structure.

9. 7. The method of claim 6, wherein the electrode assembly is composed of a unit cell, which is a bicell having a single electrode plate and electrodes on both outer surfaces of the bicell having the same polarity, or a full cell having electrodes on both outer surfaces of the bicell having opposite polarities.

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