KR-102962577-B1 - ELECTRODE ASSEMBLY AND SECONDARY BATTERY INCLUDING THE SAME

KR102962577B1KR 102962577 B1KR102962577 B1KR 102962577B1KR-102962577-B1

Abstract

An electrode assembly according to one embodiment of the present invention comprises a first electrode sheet; a second electrode sheet; and a separator interposed between the first electrode sheet and the second electrode sheet, wherein the first electrode sheet, the second electrode sheet, and the separator are wound to form a jelly roll structure. The first electrode sheet comprises a first electrode current collector and a first active material portion formed by coating an electrode active material on the surface of the first electrode current collector, and a first electrode tab is bonded to a portion of the first electrode sheet where the first electrode current collector is exposed. A protective tape is attached to cover the first electrode tab, and the protective tape comprises a first layer and a second layer located on the outside of the first layer. The first layer includes an indented portion in a recessed shape, and the first electrode tab is located in the indented portion.

Inventors

박지성

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260507
Application Date: 20210805

Claims (11)

First electrode sheet; second electrode sheet; and It includes a separator interposed between the first electrode sheet and the second electrode sheet, and The first electrode sheet, the second electrode sheet, and the separator are wound to form a jelly roll structure, and The first electrode sheet comprises a first electrode current collector and a first active material portion formed by coating an electrode active material on the surface of the first electrode current collector. A first electrode tab is bonded to the portion of the first electrode sheet where the first electrode current collector is exposed, and A protective tape is attached to cover the first electrode tab, and The protective tape comprises a first layer facing the first electrode tab and a second layer located on the outer side of the first layer and facing the separator. The first layer includes an indented portion in a recessed shape, and the first electrode tab is located in the indented portion, and The first layer above comprises a polyurethane (PU) material, and The above second layer is an electrode assembly comprising a polyimide (PI) material.
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In paragraph 1, The first layer above includes an outer periphery adjacent to the indentation, and The above-mentioned indentation is an electrode assembly that is thinner than the above-mentioned outer periphery.
In Paragraph 3, An electrode assembly in which the thickness of the outer periphery is 1.2 times or more and 7.5 times or less the thickness of the indentation.
In Paragraph 3, The above-mentioned indentation is an electrode assembly positioned corresponding to the first electrode tab.
In paragraph 1, The indentation is formed on the surface of the first layer facing the first electrode tab, and An electrode assembly in which the first electrode tab is inserted into the indentation.
In paragraph 1, The above protective tape further includes a third layer located between the first layer and the second layer, and The above third layer is an electrode assembly comprising an adhesive material.
In paragraph 1, The above protective tape further includes a fourth layer located between the first layer and the first electrode sheet, and The above-mentioned fourth layer is an electrode assembly comprising an adhesive material.
In paragraph 1, The first electrode sheet above is an anode sheet, and The above second electrode sheet is an electrode assembly that is a negative electrode sheet.
In paragraph 1, The first electrode sheet above is a rectangular sheet, and The portion of the first electrode sheet where the first electrode current collector is exposed is an electrode assembly that is a region spaced apart from both end sides of the first electrode sheet.
A secondary battery comprising an electrode assembly according to claim 1.

Description

Electrode assembly and secondary battery including the same The present invention relates to an electrode assembly and a secondary battery including the same, and more specifically, to a jelly roll-shaped electrode assembly and a secondary battery including the same. Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, much research is being conducted on secondary batteries used as their power sources. Examples of rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are widely used in the field of advanced electronic devices due to their advantages over nickel-based batteries, such as virtually no memory effect, allowing for free charging and discharging, a very low self-discharge rate, high operating voltage, and high energy density per unit weight. Rechargeable batteries are classified according to the shape of the battery case into cylindrical batteries, in which the electrode assembly is housed in a cylindrical metal can; prismatic batteries, in which the electrode assembly is housed in a rectangular metal can; and pouch batteries, in which the electrode assembly is housed in a pouch-type case made of aluminum laminate sheets. Among these, cylindrical batteries have the advantage of relatively high capacity and structural stability. The electrode assembly embedded in the battery case is a rechargeable power generator composed of a stacked structure of a positive electrode, a separator, and a negative electrode, and is classified into jellyroll type, stack type, and stack/folding type. The jellyroll type is a form in which a separator is interposed between long sheet-shaped positive and negative electrodes coated with active material and wound; the stack type is a form in which multiple positive and negative electrodes of a predetermined size are sequentially stacked with a separator interposed; and the stack/folding type is a composite structure of the jellyroll type and the stack type. Among these, the jellyroll type electrode assembly has the advantages of being easy to manufacture and having a high energy density per unit weight. An electrode tab is attached to each of the positive and negative electrodes. Specifically, an positive electrode tab made of aluminum may be attached to the positive electrode, and a negative electrode tab made of a material containing at least one of nickel and copper may be attached to the negative electrode. However, the attached positive and negative tabs create a thickness difference relative to the positive and negative electrodes, respectively, resulting in a stepped structure within the jellyroll-type electrode assembly. When an impact test is conducted on a secondary battery containing such an electrode assembly, the stepped structure formed by the tabs causes stronger impact to specific areas, which compromises the safety of the secondary battery. This is a problem that can occur not only during impact tests but also when the secondary battery is exposed to external shocks. During charging and discharging of the electrode assembly, the electrode assembly repeatedly expands and contracts, and the step structure formed by the positive tab and the negative tab can cause local deformation or distortion of the shape due to changes in the volume of the electrode assembly during charging and discharging. Accordingly, there is a high need for technology capable of solving the aforementioned problems caused by the step structure formed by the electrode tab. FIG. 1 is an exploded perspective view of a secondary battery according to one embodiment of the present invention. FIG. 2 is an exploded perspective view showing the electrode assembly included in the secondary battery of FIG. 1 before it is wound. Figure 3 is a plan view showing an enlarged view of part A of Figure 2. Figure 4 is a front view taken from direction B of Figure 3. Figure 5 is a front view showing the first layer of the protective tape in Figure 4 expanded after absorbing the electrolyte. FIG. 6 is a front view illustrating the appearance of a protective tape attached according to a comparative example of the present invention. FIG. 7 is a front view illustrating a protective tape according to another embodiment of the present invention. Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. To clearly explain the present invention, parts unrelated to the explanation have been omitted, and the same reference numerals are used for identical or sim