Electrode Assembly with Insulating Tape Attached and lithium secondary Battery Comprising the Same

Abstract

The present invention comprises an electrode stack having a plurality of anodes and a plurality of cathodes alternately stacked with a separator placed between them; an anode lead coupled to an anode tab bundle formed by overlapping anode tabs protruding from the outer periphery of each of the plurality of anodes; a cathode lead coupled to a cathode tab bundle formed by overlapping cathode tabs protruding from the outer periphery of each of the plurality of cathodes; a first insulating tape attached to at least a portion of the upper surface of the electrode stack, the upper surface of an anode coupling part where the anode tab bundle and the anode lead are coupled, and the upper surface of a cathode coupling part where the cathode tab bundle and the cathode lead are coupled; and a second insulating tape attached to at least a portion of the lower surface of the electrode stack, the lower surface of an anode coupling part where the anode tab bundle and the anode lead are coupled, and the lower surface of a cathode coupling part where the cathode tab bundle and the cathode lead are coupled, wherein the anode tab bundle and the cathode tab bundle are formed on the same outer periphery but are positioned to be spaced apart from each other, and at least one of the first insulating tape and the second insulating tape is the The invention relates to an electrode assembly having an insulating tape attached thereto, wherein a cut-out portion is formed between a positive electrode attached to a positive electrode coupling portion and a negative electrode attached to a negative electrode coupling portion, wherein at least a portion between them is removed, and a lithium secondary battery including the same.

Description

Technology Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 2024-0038034 filed March 19, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to an electrode assembly with an insulating tape attached thereto and a lithium secondary battery including the same. Specifically, the invention relates to an electrode assembly with an insulating tape of a modified form attached thereto so as to prevent the insulating tape attached to the upper and lower parts of the tab-lead joint portion in a pouch-type battery cell from fusing and affecting gas discharge, and a lithium secondary battery including the same. Background Technology

[0003] In the case of a stacked electrode assembly in which a positive electrode, a negative electrode, and a separator are located on the outer surface of at least one of the positive electrode and the negative electrode, and the positive electrode and the negative electrode are alternately stacked, all positive electrodes and all negative electrodes have at least one positive electrode tab and at least one negative electrode tab protruding from at least one outer periphery.

[0004] In the case of a pouch-type battery cell in which the above-mentioned stacked electrode assembly is housed in a pouch-type battery case, positive tabs protruding from all positive electrodes are joined so as to overlap to form a positive tab bundle, and negative tabs protruding from all negative electrodes are joined so as to overlap to form a negative tab bundle.

[0005] The above positive tab bundle is coupled with the positive lead, and the above negative tab bundle is coupled with the negative lead, and the above positive lead and the above negative lead protrude outside the pouch-type battery case to function as electrode terminals.

[0006] Each of the above positive tab bundle and the above negative tab bundle is folded into a V shape inside a pouch-type battery case while combined with the above positive lead and the above negative lead, and the part folded in this way is called a 'V-forming part'.

[0007] If the pointedly bent part of the above V-forming part comes into contact with the conductive metal layer of the pouch-type battery case, there is a risk of an internal short circuit.

[0008] Accordingly, to prevent contact between the V-forming part and the conductive metal layer of the pouch-type battery case, an insulating tape was attached to the outer surface of the V-forming part.

[0009] In this regard, FIG. 1 is a plan view of a conventional electrode assembly, and FIG. 2 is a vertical cross-sectional view of the electrode assembly of FIG. 1 and a pouch-type battery cell including the same.

[0010] Referring to FIGS. 1 and 2, an electrode assembly (100) is stacked such that a separator (112) is interposed between an anode (111) and a cathode (not shown) to form an electrode stack (110). The cathode is located on the opposite side of the anode (111) with respect to the separator (112) and has a smaller area than the separator (112), so the cathode is omitted in FIG. 1.

[0011] A plurality of positive tabs (121) protruding from the positive electrode (111) form a positive tab bundle, and the end of the positive tab bundle is coupled to a positive lead (131). A plurality of negative tabs (122) protruding from the negative electrode form a negative tab bundle, and the end of the negative tab bundle is coupled to a negative lead (132). A pair of lead films (140) are attached to the upper and lower surfaces of each of the positive lead (131) and the negative lead (132).

[0012] A first insulating tape (151) is attached to the upper surface of the electrode stack (110) in the longitudinal direction (y), the upper surface of the positive electrode tab (121), and the upper surface of the negative electrode tab (122), and a second insulating tape (152) is attached to the lower surface of the electrode stack (110) in the longitudinal direction (y), the lower surface of the positive electrode tab (121), and the lower surface of the negative electrode tab (122).

[0013] FIG. 1 shows an electrode assembly divided into L1, L2, L3, L4, and L5 along the width direction (x). FIG. 2 (a) is a vertical cross-sectional view of an electrode assembly cut parallel to the length direction (y) of the electrode assembly at each of L1, L2, L3, L4, and L5. FIG. 2 (b) shows the electrode tab bundle in FIG. 2 (a) being folded to form a V-forming part (133) and being received in a pouch-type battery case (201) in a folded state.

[0014] The vertical cross-sections of L1 and L5 are of the same shape, and the vertical cross-section of L1 is shown in FIG. 2 (a) and FIG. 2 (b). The vertical cross-sections of L2 and L4 are of the same shape except that the polarity of the electrodes is different, and the vertical cross-section of L2 is shown in FIG. 2 (a) and FIG. 2 (b).

[0015] The first insulating tape (151) is attached to cover the upper part of L3, and the second insulating tape (152) is attached to cover the lower part of L3.

[0016] The first insulating tape (151) and the second insulating tape (152) may be unoriented polypropylene (Cast Polypropylene, hereinafter referred to as "CPP") tapes, and the melting point of CPP is 160°C.

[0017] Referring to FIG. 2, in L3 of (a), the first insulating tape (151) and the second insulating tape (152) are not attached to each other, but in L3 of (b), the first insulating tape (151) and the second insulating tape (152) come close to each other while forming a V-forming portion (133). At this time, the first insulating tape (151) and the second insulating tape (152) may be attached.

[0018] FIG. 3 is a vertical cross-sectional view showing the state in which the pouch-type battery case is expanded when the internal pressure of the pouch-type battery cell of FIG. 2 increases. FIG. 3 is a form in which the electrode tab, electrode lead, and lead film are omitted for convenience of explanation, and is a vertical cross-sectional view of L3 of FIG. 2.

[0019] Referring to FIG. 3, (a) is a state in which the pouch-type battery case (201) is expanded by gas generated during the charging and discharging process of the lithium secondary battery, and the thick arrow indicates the direction of gas expansion. (b) is a state in which venting begins as the temperature of the lithium secondary battery increases above the temperature at which the internal adhesive layer of the pouch-type battery case (201) melts, and is approximately 130°C or higher. The thick arrow indicates the gas flow, and the gas inside the pouch-type battery case is discharged to the outside through the venting section. (c) is a state in which the temperature of the lithium secondary battery rises above 160°C, causing the first insulating tape (151) and the second insulating tape (152) to melt and form a fused section (153). The fused first insulating tape (151) and second insulating tape (152) block the venting portion of the pouch-type battery case (201) from which gas was discharged in (b), so that gas cannot be discharged and gradually accumulates inside the pouch-type battery case (201). The thick arrow indicates the flow of gas.

[0020] In such a situation, the pouch-type battery case (201) that cannot withstand the internal pressure may explode, which is pointed out as a problem that threatens the safety of the user of the lithium secondary battery.

[0021] Therefore, even if insulating tape is attached to prevent damage to the pouch-type battery case caused by the V-forming portion of the electrode tab bundle, there is a need for technology that ensures smooth gas discharge when the internal pressure of the battery cell increases, thereby enhancing safety. The problem to be solved

[0022] The present invention aims to solve the above-mentioned problems by providing an electrode assembly with an insulating tape attached and a lithium secondary battery including the same, which can prevent thermal runaway and explosion of the battery cell by securing a passage for gas discharge even when the insulating tape is attached to prevent damage to the pouch-type battery case and internal short circuit caused by the V-forming portion of the electrode tab bundle. means of solving the problem

[0023] An electrode assembly according to the present invention for achieving the above purpose comprises: an electrode laminate in which a plurality of anodes and a plurality of cathodes are alternately stacked with a separator placed between them; an anode lead coupled to an anode tab bundle formed by overlapping anode tabs protruding from the outer periphery of each of the plurality of anodes; a cathode lead coupled to a cathode tab bundle formed by overlapping cathode tabs protruding from the outer periphery of each of the plurality of cathodes; a first insulating tape attached to at least a portion of the upper surface of the electrode laminate, the upper surface of an anode coupling part where the anode tab bundle and the anode lead are coupled, and the upper surface of a cathode coupling part where the cathode tab bundle and the cathode lead are coupled; and at least a portion of the lower surface of the electrode laminate, the lower surface of an anode coupling part where the anode tab bundle and the anode lead are coupled, and a second insulating tape attached to the lower surface of a cathode coupling part where the cathode tab bundle and the cathode lead are coupled, wherein the anode tab bundle and the cathode tab bundle are formed on the same outer periphery but are positioned to be spaced apart from each other, and the first insulating tape And at least one of the second insulating tapes may have a cut-out portion formed therein in which at least a part between the anode portion attached to the anode coupling portion and the cathode portion attached to the cathode coupling portion is removed.

[0024] The above-mentioned cut portion may include a first cut portion formed on the first insulating tape and a second cut portion formed on the second insulating tape.

[0025] The above-mentioned cut section may be composed of any one selected from the group consisting of planar rectangular, square, triangular, trapezoidal, semicircular, and semi-elliptical shapes.

[0026] The width of the positive portion of the first insulating tape and the second insulating tape is greater than the width of the positive tab, and the width of the negative portion of the first insulating tape and the second insulating tape may be greater than the width of the negative tab.

[0027] The first insulating tape and the second insulating tape include a first region attached to the outer surface of the electrode laminate, and a second region including the anode and the cathode as the remaining portion excluding the first region, and the first region may include an extension portion that extends further than both ends of the second region with respect to the width direction of the electrode laminate.

[0028] The shortest distance from the first end in the longitudinal direction of the first region to the cut portion may be the same as the distance from the first end in the longitudinal direction of the extension to the second end opposite the first end.

[0029] The extension of the first insulating tape extends downward along the side in the thickness direction of the electrode laminate, and the extension of the second insulating tape extends upward along the side in the thickness direction of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape may not overlap on the side of the electrode laminate.

[0030] The extension of the first insulating tape extends downward along the side in the thickness direction of the electrode laminate, and the extension of the second insulating tape extends upward along the side in the thickness direction of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape may overlap on the side of the electrode laminate.

[0031] The extension of the first insulating tape extends through the side in the thickness direction of the electrode laminate to the lower surface of the electrode laminate, and the extension of the second insulating tape extends through the side in the thickness direction of the electrode laminate to the upper surface of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape may overlap at the side of the electrode laminate, the upper surface of the electrode laminate, and the lower surface of the electrode laminate.

[0032] The first insulating tape and the second insulating tape include a first layer attached to the electrode laminate, the positive coupling portion and the negative coupling portion, and a second layer located on the first layer, wherein the first layer is an adhesive layer containing an adhesive material and the second layer may be an insulating layer.

[0033] Additionally, the electrode assembly according to the present invention comprises: an electrode laminate in which a plurality of anodes and a plurality of cathodes are alternately stacked with a separator placed between them; an anode lead coupled to an anode tab bundle in which anode tabs protruding from the outer periphery of each of the plurality of anodes are overlapped; a cathode lead coupled to a cathode tab bundle in which cathode tabs protruding from the outer periphery of each of the plurality of cathodes are overlapped; at least a portion of the upper surface of the electrode laminate, the upper surface of an anode coupling part in which the anode tab bundle and the anode lead are coupled, the upper surface of a cathode coupling part in which the cathode tab bundle and the cathode lead are coupled, and a first insulating tape attached to the side of the electrode laminate between the anode coupling part and the cathode coupling part; and at least a portion of the lower surface of the electrode laminate, the lower surface of an anode coupling part in which the anode tab bundle and the anode lead are coupled, the lower surface of a cathode coupling part in which the cathode tab bundle and the cathode lead are coupled, and a second insulating tape attached to the side of the electrode laminate between the anode coupling part and the cathode coupling part, and the first insulating The tape and the second insulating tape may overlap each other on the side of the electrode laminate between the positive coupling part and the negative coupling part.

[0034] The present invention provides a lithium secondary battery comprising the electrode assembly, specifically comprising the electrode assembly and a battery case that accommodates the electrode assembly inside, wherein the battery case comprises a first case and a second case made of a laminate sheet comprising a metal layer and a resin layer, at least one of the first case and the second case has an electrode assembly receiving portion formed therein, and the outer periphery of the first case and the second case is heat-fused to each other and sealed, and the positive tab bundle and the negative tab bundle of the electrode assembly can be folded in the space between the electrode laminate and the battery case to form a V-forming portion.

[0035] The one with a relatively thicker thickness between the first insulating tape and the second insulating tape can be attached to the outside of the V-forming part.

[0036] In addition, the present invention provides a battery pack comprising the above-mentioned lithium secondary battery as a unit cell.

[0037] The present invention can also be provided in a form that combines various means for solving the above problem. Effects of the invention

[0038] The present invention can maintain an open state of the venting portion when venting a lithium secondary battery by removing the portion where unnecessary fusion occurs in the insulating tape attached to the outer surface of the V-forming portion of the electrode tab bundle.

[0039] As a result, internal gas can be vented smoothly, so the temperature of the lithium secondary battery does not rise above a certain level.

[0040] Therefore, thermal runaway and explosion of lithium secondary batteries can be prevented, thereby preventing secondary accidents such as casualties.

[0041] In addition, resistance can be reduced by configuring the anode, separator, and cathode constituting the electrode assembly to be in close contact. Brief explanation of the drawing

[0042] Figure 1 is a plan view of a conventional electrode assembly. FIG. 2 is a vertical cross-sectional view of the electrode assembly of FIG. 1 and a pouch-type battery cell including the same. Figure 3 is a vertical cross-sectional view showing the state in which the pouch-type battery case is expanded when the internal pressure of the pouch-type battery cell of Figure 2 increases. FIG. 4 is a plan view of an electrode assembly according to the first embodiment of the present invention. Figure 5 is a perspective view of the electrode assembly of Figure 4. FIG. 6 is a vertical cross-sectional view of the electrode assembly of FIG. 4 and a pouch-type battery cell including the same. FIG. 7 is a plan view showing various types of cutouts in an electrode assembly according to the present invention. FIG. 8 is a perspective view of an electrode assembly according to a second embodiment of the present invention. FIG. 9 is a perspective view of an electrode assembly according to a third embodiment of the present invention. FIG. 10 is a perspective view of an electrode assembly according to the fourth embodiment of the present invention. FIG. 11 is a perspective view of an electrode assembly according to the fifth embodiment of the present invention. Figure 12 is a graph of the temperature change over time of the comparative example. Figure 13 is a photo of the result of the comparative example. Figure 14 is a graph of the temperature change over time of an example. Figure 15 is a photograph of the result of an example. Specific details for implementing the invention

[0043] Embodiments that enable a person skilled in the art to easily practice the present invention are described in detail below with reference to the attached drawings. In describing the operating principles of the embodiments of the present invention in detail, specific descriptions of related known functions or configurations are omitted if it is determined that such detailed descriptions may unnecessarily obscure the essence of the present invention.

[0044] The same reference numerals are used for parts having similar functions and operations throughout the drawings. Throughout the specification, when a part is described as being connected to another part, this includes not only cases where they are directly connected but also cases where they are indirectly connected with other elements in between. Furthermore, the inclusion of a certain component means that, unless specifically stated otherwise, it does not exclude other components but rather implies that additional components may be included.

[0045] Descriptions that specify components by limiting or adding them may be applied to all inventions unless specifically limited, and are not limited to descriptions of specific inventions.

[0046] Throughout the description of the invention and claims of this application, anything indicated in the singular includes cases where it is plural unless otherwise noted.

[0047] Throughout the description of the invention and the claims of the present invention, "or" includes "and" unless otherwise noted. Therefore, "comprising A or B" means all three of the above cases: including A, including B, or including both A and B.

[0048] The present invention is described in detail with reference to the drawings and embodiments.

[0049] FIG. 4 is a plan view of an electrode assembly according to a first embodiment of the present invention, FIG. 5 is a perspective view of the electrode assembly of FIG. 4, and FIG. 6 is a vertical cross-sectional view of the electrode assembly of FIG. 4 and a pouch-type battery cell including the same.

[0050] Referring to FIGS. 4 to 6, the electrode assembly (100) according to the present invention comprises: an electrode stack (110) in which a plurality of positive electrodes (111) and a plurality of negative electrodes (not shown) are alternately stacked with a separator (112) in between; a positive lead (131) coupled to a positive electrode tab bundle in which positive electrode tabs (121) protruding from the outer periphery of each of the plurality of positive electrodes (111) are superimposed; a negative lead (132) coupled to a negative electrode tab bundle in which negative electrode tabs (122) protruding from the outer periphery of each of the plurality of negative electrodes are superimposed; a first insulating tape (151) attached to at least a portion of the upper surface of the electrode stack (110), the upper surface of a positive electrode coupling part (123) in which a positive electrode tab bundle and a positive lead (131) are coupled, and the upper surface of a negative electrode coupling part (124) in which a negative electrode tab bundle and a negative lead (132) are coupled; and the lower surface of the electrode stack (110). It includes a second insulating tape (152) attached to at least a portion of the lower surface of the positive coupling part (123) in which the positive tab bundle and the positive lead (131) are combined, and the lower surface of the negative coupling part (124) in which the negative tab bundle and the negative lead (132) are combined.

[0051] The first insulating tape (151) and the second insulating tape (152) are attached to the upper end in the longitudinal direction (y) of the electrode laminate (110) and are further extended in the direction of the positive lead (131) and the negative lead (132), passing through the positive tab bundle and the negative tab bundle, and extending to the positive coupling portion (123) and the negative coupling portion. However, if the first insulating tape (151) and the second insulating tape (152) are located on the upper side in the longitudinal direction (y) of the electrode laminate (110), they may be extended downward in the longitudinal direction (y), unlike what is shown in the drawing.

[0052] A pair of lead films (140) may be further attached to the upper and lower surfaces of each positive lead (131) and negative lead (132). The lead films (140) are attached to improve the adhesion between the pouch-type battery case and the positive lead (131) and negative lead (132), and are positioned at a location that overlaps with the outer periphery sealing portion of the pouch-type battery case after the electrode assembly (100) is housed in the pouch-type battery case. In other words, the outer periphery of the pouch-type battery case is sealed while the lead films (140) are positioned to overlap with the outer periphery sealing portion of the pouch-type battery case.

[0053] The positive electrode tab bundle and the negative electrode tab bundle are formed on the same outer periphery of the electrode stack (110) but are positioned so as to be spaced apart from each other.

[0054] At least one of the first insulating tape (151) and the second insulating tape (152) has a cut-out portion (160) formed between the positive portion (153) attached to the positive coupling portion and the negative portion (154) attached to the negative coupling portion, in which at least a portion is removed.

[0055] When comparing the first insulating tape (151) and the second insulating tape (152) according to the present invention with the first insulating tape (151) and the second insulating tape (152) shown in FIG. 1, there is a difference in that at least a portion of the part covering the upper and lower parts of the L3 region in FIG. 4 is removed.

[0056] The present invention includes not only having a cut portion (160) formed in at least one of the first insulating tape (151) and the second insulating tape (152), but also having a cut portion (160) formed in both the first insulating tape (151) and the second insulating tape (152).

[0057] The electrode assembly according to the present invention includes a cut portion (160) in a form in which the fused portion that blocked the venting portion was removed by melting and heat-fusion of the first insulating tape and the second insulating tape in the past, so that the internal gas of the lithium secondary battery can be smoothly discharged.

[0058] The first insulating tape (151) and the second insulating tape (152) are attached to the outer surface of the positive tab bundle and the negative tab bundle to prevent internal short circuits in the lithium secondary battery. It is preferable that the width of the positive portion (153) of the first insulating tape (151) and the second insulating tape (152) be greater than or equal to the width (G1) of the positive tab (121), and the width of the negative portion (154) be greater than or equal to the width (G2) of the negative tab (122).

[0059] Specifically, as shown in FIG. 4, when the first insulating tape (151) and the second insulating tape (152) are attached to the electrode laminate (110), the positive tab bundle, the positive connection part, the negative tab bundle and the negative connection part, the minimum size of the first insulating tape (151) and the second insulating tape (152) can be configured as follows.

[0060] The maximum size (A) in the width direction (x) of the first insulating tape (151) and the maximum size (B) in the width direction (x) of the second insulating tape (152) may vary depending on the width of the electrode laminate (110).

[0061] Since the size of the anode (111) constituting the electrode laminate (110) is the smallest and the size of the separator (112) is the largest, the length (C1, C3) between the outer periphery of the anode and the first and second insulating tapes may be 0 mm or more, and more specifically, 1.5 mm or more.

[0062] The length (D1) between the first insulating tape (151) and the lead film (140) and the length (D2) between the second insulating tape (152) and the lead film (140) may be 0.08 ± 0.75 mm.

[0063] In the longitudinal direction (y), the minimum length (E1) between the end of the positive tab (121) and the end of the first and second insulating tapes and the minimum length (E2) between the end of the negative tab (122) and the end of the first and second insulating tapes is 0.1 mm.

[0064] When the width of the positive portion (153) of the first and second insulating tapes is greater than the width (G1) of the positive tab (121) and the width of the negative portion (154) is greater than the width (G2) of the negative tab (122), the minimum length (F1) of the first and second insulating tapes extended further in the width direction (x) from the positive tab (121) and the minimum length (F2) of the first and second insulating tapes extended further in the width direction (x) from the negative tab (122) is 0.1 mm.

[0065] In addition, the thicknesses of the first insulating tape (151) and the second insulating tape (152) are configured differently. As shown in FIG. 6, when the V-forming portion of the electrode tab bundle is bent downwards in a convex shape, the thickness of the second insulating tape (152) attached to the outside of the convex portion may be thicker than the thickness of the first insulating tape (151). This is to prevent the risk of internal short circuits by supplementing the thickness, as there is a greater risk of the second insulating tape (152) being damaged in the pointed portion caused by the bending.

[0066] For example, among the first insulating tape and the second insulating tape, the thickness of the relatively thin one may be 10㎛ to 50㎛, and the thickness of the relatively thick one may be 30㎛ to 70㎛, and the one attached to the convex outer surface of the V-forming part of the electrode tab bundle may be configured to be relatively thick, and may be selected within the above range.

[0067] The first insulating tape (151) and the second insulating tape (152) include a first region (150a) attached to the outer surface of the electrode laminate (110), and a second region (150b) including an anode (153) and a cathode (154) as the remaining portion excluding the first region (150a).

[0068] The first region (150a) includes an extension (155) that extends further than both ends of the second region (150b) with respect to the width direction (x) of the electrode laminate (110).

[0069] The first insulating tape (151) and the second insulating tape (152) attached to the first region (150a) can serve to compress the electrode laminate (110), so the pressure applied to the electrode laminate (110) can be increased by including an extension part (155). In particular, if a sliding part is formed in which the outer periphery of the electrode composite layer gradually lowers and becomes inclined, non-adhesion may occur between the electrode and the separator, leading to increased resistance and the precipitation of lithium. In such cases, the pressure applied to the electrode laminate (110) can be increased by increasing the length (y) and width (x) dimensions of the extension part (155).

[0070] FIG. 4 shows an electrode assembly divided into L1, L2, L3, L4, and L5 along the width direction (x). FIG. 6 (a) is a vertical cross-sectional view of an electrode assembly cut parallel to the length direction (y) of the electrode assembly at each of L1, L2, L3, L4, and L5. FIG. 6 (b) shows the electrode tab bundle in FIG. 6 (a) being folded to form a V-forming part (133) and being received in a pouch-type battery case (201) in a folded state.

[0071] The lithium secondary battery illustrated in FIG. 6 (b) is a pouch-type battery cell and includes a pouch-type battery case (201) that accommodates an electrode assembly inside, and the battery case (201) is composed of a laminate sheet including a metal layer and a resin layer.

[0072] The battery case (201) includes a first case (201a) and a second case (201b), and the first case (201a) and the second case (201b) may be separated from each other, or may be connected to each other and bent at one side of the outer periphery.

[0073] In FIG. 6 (b), a concave electrode assembly receiving portion (200) is formed in the second case (201b) to accommodate the electrode assembly, whereas, alternatively, the electrode assembly receiving portion may be formed in the first case (201a), and the V-forming portion (133) may be convex upward.

[0074] The first case (201a) and the second case (201b) are sealed by heat-fusion of their outer peripheries, and the V-forming portion (133), formed by bending the positive tab bundle and the negative tab bundle of the electrode assembly, is located in the space between the electrode laminate (110) and the battery case (201).

[0075] The vertical cross-sections of L1 and L5 are of the same shape, and the vertical cross-section of L1 is shown in Fig. 6 (a) and Fig. 6 (b). The vertical cross-sections of L2 and L4 are of the same shape except for the difference in the polarity of the electrodes, and the vertical cross-section of L2 is shown in Fig. 6 (a) and Fig. 6 (b).

[0076] The first insulating tape (151) and the second insulating tape (152) are in a form in which the portions added to the upper and lower parts of L3 have been removed. In L3 of FIGS. 6 (a) and FIGS. 6 (b), the first insulating tape (151) and the second insulating tape (152) are spaced apart and are in the same form as L1 and L5. That is, the first insulating tape (151) and the second insulating tape (152) do not form an attachment to each other at the cut portion (160).

[0077] The first insulating tape (151) and the second insulating tape (152) may be unoriented polypropylene (Cast Polypropylene, hereinafter referred to as "CPP") tapes, and the melting point of CPP is 160°C. Alternatively, the first insulating tape (151) and the second insulating tape (152) may be in the form of having an acrylic adhesive applied to one side of the polypropylene layer.

[0078] In one specific example, the first insulating tape (151) and the second insulating tape (152) include a first layer (151a, 152a) attached to the electrode laminate (110), the positive coupling portion (123), and the negative coupling portion (124), and a second layer (151b, 152b) located on the first layer (151a, 152a), wherein the first layer (151a, 152a) is an adhesive layer containing an adhesive material, and the second layer (151b, 152b) may be an insulating layer.

[0079] The first insulating tape and the second insulating tape can be stably attached to the electrode laminate, the positive electrode coupling part (123) and the negative electrode coupling part (124) by the above adhesive layer, and the contact between the positive and negative electrodes can be prevented by the above insulating layer.

[0080] The adhesive material included in the first adhesive layer may include, for example, an epoxy adhesive, an acrylic adhesive, or a cyanoacrylate adhesive, and the insulating material constituting the insulating layer may include, for example, one or more selected from the group consisting of silicone, mica, rubber, ceramic, and insulating polymers including polyvinyl alcohol, polyimide, polymethyl methacrylate, polystyrene, etc.

[0081] FIG. 7 is a plan view showing various types of cutouts in an electrode assembly according to the present invention.

[0082] In the electrode assembly shown in Fig. 4, the cut section (160) is a flat rectangular or square.

[0083] Referring to FIG. 7, (a) the cut portion (160) is a triangle in planar shape, (b) the cut portion (160) is a trapezoid, and (c) the cut portion (160) is configured in a semi-elliptical shape.

[0084] However, the shape of the cut portion is not limited to the shape depicted in the drawings within this specification if at least one of the first insulating tape and the second insulating tape is in a shape where at least a portion is cut off at L3.

[0085] Even if the shape of the cut section (160) varies as such, the shortest distance (H) from the first end (155a) in the longitudinal direction of the first region (150a) to the cut section (160) is the same as the distance from the first end (155a) in the longitudinal direction of the extension to the second end (155b) opposite the first end (155a).

[0086] FIG. 8 is a perspective view of an electrode assembly according to a second embodiment of the present invention. Referring to FIG. 8, the extension (155) of the first insulating tape (151) attached to the electrode laminate (110) extends downward along the side (170) in the thickness direction (z) of the electrode laminate (110), and the extension (155) of the second insulating tape (152) extends upward along the side (170) in the thickness direction (z) of the electrode laminate (110), and the extension (155) of the first insulating tape (151) and the extension (155) of the second insulating tape (152) do not overlap on the side (170) of the electrode laminate (110).

[0087] FIG. 9 is a perspective view of an electrode assembly according to a third embodiment of the present invention. Referring to FIG. 9, the extension (155) of the first insulating tape (151) attached to the electrode laminate (110) extends downward along the side (170) in the thickness direction (z) of the electrode laminate (110), and the extension (155) of the second insulating tape (152) extends upward along the side (170) in the thickness direction (z) of the electrode laminate (110), and the extension (155) of the first insulating tape (151) and the extension (155) of the second insulating tape (152) overlap on the side (170) of the electrode laminate (110).

[0088] FIG. 10 is a perspective view of an electrode assembly according to a fourth embodiment of the present invention. Referring to FIG. 10, the extension portion (155) of the first insulating tape (151) extends through the side (170) in the thickness direction (z) of the electrode laminate (110) to the lower surface of the electrode laminate (110), and the extension portion (155) of the second insulating tape (152) extends through the side (170) in the thickness direction (z) of the electrode laminate (110) to the upper surface (180) of the electrode laminate (110), and the extension portion (155) of the first insulating tape (151) and the extension portion (155) of the second insulating tape (152) overlap on the side (170) of the electrode laminate (110), the upper surface (170) of the electrode laminate (110), and the lower surface of the electrode laminate (110).

[0089] At this time, the first insulating tape (151) and the second insulating tape (152) press the electrode laminate (110), and when a sliding portion is formed in which the thickness of the outer periphery where the electrode tab is located in the positive composite layer and the negative composite layer becomes thin, the adhesion between the electrode and the separator can be increased in the sliding portion.

[0090] FIG. 11 is a perspective view of an electrode assembly according to the fifth embodiment of the present invention. Referring to FIG. 11, the electrode assembly (100) according to the present invention comprises: an electrode laminate (110) in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked with a separator between them; a positive lead (131) coupled to a positive tab bundle in which positive tabs protruding from the outer periphery of each of the plurality of positive electrodes are overlapped; a negative lead (132) coupled to a negative tab bundle in which negative tabs protruding from the outer periphery of each of the plurality of negative electrodes are overlapped; at least a portion of the upper surface (180) of the electrode laminate (110), the upper surface of a positive coupling part (123) in which the positive tab bundle and the positive lead (131) are coupled, the upper surface of a negative coupling part (124) in which the negative tab bundle and the negative lead (132) are coupled, and a first insulating tape (151) attached to the side surface (171) of the electrode laminate (110) between the positive coupling part (123) and the negative coupling part (124); and It includes a second insulating tape (152) attached to at least a portion of the lower surface of the electrode laminate (110), the lower surface of the anode coupling part (123) where the anode tab bundle and the anode lead (131) are coupled, the lower surface of the cathode coupling part (124) where the cathode tab bundle and the cathode lead (132) are coupled, and the side surface (171) of the electrode laminate (110) between the anode coupling part (123) and the cathode coupling part (124).

[0091] The first insulating tape (151) and the second insulating tape (152) may overlap each other on the side (171) of the electrode laminate (110) between the positive coupling portion (123) and the negative coupling portion (124). Alternatively, unlike as shown in FIG. 11, the first insulating tape (151) and the second insulating tape (152) may be attached in a manner that does not overlap each other on the side (171) of the electrode laminate (110) between the positive coupling portion (123) and the negative coupling portion (124).

[0092] At this time, the first insulating tape (151) and the second insulating tape (152) wrap around and press the outer periphery of the side where the electrode tab of the electrode laminate (110) protrudes. When a sliding portion is formed in which the thickness of the outer periphery side where the electrode tab is located is thinned in the positive composite layer and the negative composite layer, the adhesion between the electrode and the separator can be increased in the sliding portion.

[0093] The following description refers to embodiments of the present invention, but this is for the sake of easier understanding of the present invention and does not limit the scope of the present invention.

[0094] <Comparative Example>

[0095] An electrode stack is prepared in which a plurality of anodes and a plurality of cathodes are alternately stacked with a separator placed between them. The anode tabs of the electrode stack are welded to form an anode tab bundle, and then the anode leads are connected. The cathode tabs of the electrode stack are welded to form a cathode tab bundle, and then the cathode leads are connected.

[0096] An electrode assembly was manufactured by attaching the first insulating tape and the second insulating tape of the form shown in Fig. 1 to the electrode laminate, the positive tab bundle, the positive coupling part, the negative tab bundle, and the negative coupling part.

[0097] After housing the above electrode assembly in a pouch-type battery case, the electrolyte was injected and sealed to assemble a pouch-type battery cell.

[0098] Twelve pouch-type battery cells manufactured using the same method as above were prepared.

[0099] A temperature sensor was attached to the center of the wide outer surface of the electrode laminate in the above pouch-type battery cell.

[0100] After setting the temperature of the heating test chamber to 130 degrees, the 12 pouch-type battery cells were placed in the heating test chamber, and the temperature change of the temperature sensor was measured for 30 minutes.

[0101] Figure 12 is a graph of the temperature change over time of the comparative example.

[0102] Referring to Fig. 12, it was measured that as time passed, the temperature of the heating test chamber and the temperature of the battery cell rose to about 120°C to 130°C, and after about 30 minutes, the temperature of the five pouch-type battery cells and the temperature of the heating test chamber rose rapidly to 200°C.

[0103] Figure 13 is a photo of the result of the comparative example.

[0104] Figure 13 is a photograph taken of the electrode assembly receiving portion and sealing portion of the pouch-type battery case after disassembling the pouch-type battery cell and removing the electrode laminate.

[0105] Referring to FIG. 13, it can be seen that the first insulating tape (151) and the second insulating tape (152) are strongly fused between the positive tab (121) and the negative tab (122) to form a fused portion (153). As the first insulating tape and the second insulating tape are fused in this way, the venting portion of the pouch-type battery cell is blocked, and it can be expected that thermal runaway occurred as shown in FIG. 12.

[0106] <Example>

[0107] Twenty pouch-type battery cells were manufactured in the same manner as the comparative example, except that the first insulating tape and the second insulating tape of the form shown in Fig. 4 were used as electrode assemblies, and a heating experiment was conducted under the same conditions as the comparative example.

[0108] Figure 14 is a graph of the temperature change over time of an example.

[0109] Referring to Fig. 14, over time, the temperature of the heating experiment chamber rises to 130°C and remains constant.

[0110] The temperature of the battery cells rose to a higher temperature than the temperature of the heating test chamber, but the maximum temperature of the 20 pouch-type battery cells was about 150°C, and all 20 pouch-type battery cells maintained the same temperature as the heating test chamber after reaching the maximum temperature.

[0111] Figure 15 is a photograph of the result of an example.

[0112] Figure 15 was taken under the same conditions as Figure 13.

[0113] Referring to FIG. 15, the first insulating tape (151) and the second insulating tape (152) have a cut portion (160) formed therein, so the first insulating tape (151) and the second insulating tape (152) are not between the positive tab (121) and the negative tab (122).

[0114] When the melting point of the adhesive layer of the pouch-type battery case, 130°C, is reached, venting of the pouch-type battery cell begins, and since no fused area is formed, the venting area is not blocked. Therefore, it can be expected that gas is discharged smoothly. In addition, a thermal runaway phenomenon like that of the comparative example did not occur.

[0115] A person skilled in the art to which the present invention pertains would be able to perform various applications and modifications within the scope of the present invention based on the above content. Explanation of the symbols

[0116] 100: Electrode assembly 110: Electrode laminate 111: Bipolar 112: Separator 121: Positive tab 122: Cathode tab 123: Positive coupling part 124: Cathode coupling part 131: Positive lead 132: Cathode lead 133: V-forming part 140: Lead film 150a: First region 150b: Second area 151: First insulation tape 151a, 152a: 1st side 151b, 152b: 2nd side 152: Second insulation tape 153: Fusion joint 153: Bipolar region 154: Cathode 155: Extension part 155a: First end 155b: Second end 160: Cut section 170, 171: Side 180: Top surface 200: Electrode assembly receiving portion 201: Pouch-type battery case

Claims

Claim 1 An electrode laminate in which a plurality of anodes and a plurality of cathodes are alternately stacked with a separator placed between them; an anode lead coupled to an overlapping anode tab bundle in which anode tabs protruding from the outer periphery of each of the plurality of anodes are coupled; a cathode lead coupled to an overlapping cathode tab bundle in which cathode tabs protruding from the outer periphery of each of the plurality of cathodes are coupled; and a first insulating tape attached to at least a portion of the upper surface of the electrode laminate, the upper surface of an anode coupling portion in which the anode tab bundle and the anode lead are coupled, and the upper surface of a cathode coupling portion in which the cathode tab bundle and the cathode lead are coupled. The electrode assembly comprises: a second insulating tape attached to at least a portion of the lower surface of the electrode laminate, the lower surface of the anode coupling portion to which the anode tab bundle and the anode lead are coupled, and the lower surface of the cathode coupling portion to which the cathode tab bundle and the cathode lead are coupled; wherein the anode tab bundle and the cathode tab bundle are formed on the same outer periphery but are positioned to be spaced apart from each other, and at least one of the first insulating tape and the second insulating tape has a cut-out portion formed therein in which at least a portion between the anode portion attached to the anode coupling portion and the cathode portion attached to the cathode coupling portion is removed. Claim 2 In claim 1, the above-mentioned cutting portion comprises a first cutting portion formed on a first insulating tape and a second cutting portion formed on a second insulating tape, forming an electrode assembly. Claim 3 In paragraph 2, the electrode assembly is composed of any one selected from the group consisting of a planar rectangular, square, triangular, trapezoidal, semicircular, and semi-elliptical shape. Claim 4 An electrode assembly according to claim 1, wherein the width of the positive portion of the first insulating tape and the second insulating tape is greater than the width of the positive tab, and the width of the negative portion of the first insulating tape and the second insulating tape is greater than the width of the negative tab. Claim 5 In claim 4, the first insulating tape and the second insulating tape comprise a first region attached to the outer surface of the electrode laminate, and a second region including the anode and the cathode as the remaining portion excluding the first region, and the first region comprises an extension portion that extends further than both ends of the second region with respect to the width direction of the electrode laminate. Claim 6 In claim 5, the shortest distance from the first end in the longitudinal direction of the first region to the cut portion is the same as the distance from the first end in the longitudinal direction of the extension to the second end opposite the first end, in an electrode assembly. Claim 7 In claim 5, the extension of the first insulating tape extends downward along the side in the thickness direction of the electrode laminate, and the extension of the second insulating tape extends upward along the side in the thickness direction of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape do not overlap on the side of the electrode laminate, forming an electrode assembly. Claim 8 In claim 5, the extension of the first insulating tape extends downward along the side in the thickness direction of the electrode laminate, and the extension of the second insulating tape extends upward along the side in the thickness direction of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape overlap on the side of the electrode laminate. Claim 9 In claim 5, the extension of the first insulating tape extends through the side in the thickness direction of the electrode laminate to the lower surface of the electrode laminate, and the extension of the second insulating tape extends through the side in the thickness direction of the electrode laminate to the upper surface of the electrode laminate, and the extension of the first insulating tape and the extension of the second insulating tape overlap at the side of the electrode laminate, the upper surface of the electrode laminate, and the lower surface of the electrode laminate. Claim 10 In claim 1, the first insulating tape and the second insulating tape comprise an electrode laminate, a first layer attached to the positive coupling portion and the negative coupling portion, and a second layer located on the first layer, wherein the first layer is an adhesive layer containing an adhesive material and the second layer is an insulating layer. Claim 11 An electrode laminate in which a plurality of anodes and a plurality of cathodes are alternately stacked with a separator placed between them; an anode lead coupled to an overlapping anode tab bundle in which anode tabs protruding from the outer periphery of each of the plurality of anodes are coupled; a cathode lead coupled to an overlapping cathode tab bundle in which cathode tabs protruding from the outer periphery of each of the plurality of cathodes are coupled; and a first insulating tape attached to at least a portion of the upper surface of the electrode laminate, the upper surface of an anode coupling portion in which the anode tab bundle and the anode lead are coupled, the upper surface of a cathode coupling portion in which the cathode tab bundle and the cathode lead are coupled, and the side of the electrode laminate between the anode coupling portion and the cathode coupling portion. The electrode assembly comprises: at least a portion of the lower surface of the electrode laminate; the lower surface of the anode coupling portion where the anode tab bundle and the anode lead are coupled; the lower surface of the cathode coupling portion where the cathode tab bundle and the cathode lead are coupled; and a second insulating tape attached to the side of the electrode laminate between the anode coupling portion and the cathode coupling portion; wherein the first insulating tape and the second insulating tape increase the adhesion between the electrode and the separator in a sliding portion where the thickness of the outer periphery side where the electrode tab is located becomes thin. Claim 12 In claim 11, the first insulating tape and the second insulating tape are electrode assemblies that overlap each other on the side of the electrode laminate between the positive coupling part and the negative coupling part. Claim 13 A lithium secondary battery comprising an electrode assembly according to any one of claims 1 to 12, and a battery case that accommodates the electrode assembly inside, wherein the battery case comprises a first case and a second case made of a laminate sheet including a metal layer and a resin layer, at least one of the first case and the second case has an electrode assembly receiving portion formed therein, and the outer periphery of the first case and the second case is heat-fused to each other to form a seal, and the positive tab bundle and negative tab bundle of the electrode assembly are folded in the space between the electrode laminate and the battery case to form a V-forming portion. Claim 14 In paragraph 13, a lithium secondary battery in which the relatively thicker of the first insulating tape and the second insulating tape is attached to the outside of the V-forming part. Claim 15 A battery pack comprising a lithium secondary battery according to Paragraph 13 as a unit cell.

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