Curved secondary battery including electrode support and method of manufacturing same

Abstract

The curved battery cell produced by the curved battery cell production jig has a circular shape with a specific curvature, and when the curved battery cell is repeatedly charged and discharged in a device provided with the curved battery cell, the curved battery cell is deformed. Disclosed are a curved secondary battery including an electrode support formed in an electrode assembly to prevent deformation of a curved battery cell so that the curved battery cell can operate without damage in a device requiring energy, and a method of manufacturing the same, wherein the shape of the secondary battery can be maintained even after repeated charging and discharging.

Description

Technical Field

[0001] This application claims the benefit of priority of Korean Patent Application No. 2023-0125427, filed on September 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a bent secondary battery including an electrode support and a method of manufacturing the same. Specifically, a bent battery cell produced using a bent battery cell production jig has a circular shape with a specific curvature, and when the bent battery cell is repeatedly charged and discharged in a device provided with the bent battery cell, the bent battery cell is deformed. The present invention relates to a bent secondary battery including an electrode support formed in an electrode assembly to prevent deformation of the bent battery cell so that the bent battery cell can operate without damage in a device that requires energy, and a method of manufacturing the same. Background Art

[0003] As the safety and capacity of lithium secondary batteries that can be charged and discharged have rapidly increased, the types of devices using lithium secondary batteries as an energy source have increased in number.

[0004] For example, lithium secondary batteries have been widely used as an energy source for wireless mobile devices or wearable devices worn on the body of small multifunctional products, and have also been used as an energy source for electric vehicles and hybrid electric vehicles as alternatives to existing gasoline and diesel vehicles that cause air pollution, or as a medium- or large-sized battery pack configured for an energy storage system (ESS).

[0005] According to the shape of the battery case, lithium secondary batteries are classified into cylindrical battery cells having an electrode assembly installed in a cylindrical metal can; prismatic battery cells having an electrode assembly installed in a prismatic metal can; or pouch-shaped battery cells having an electrode assembly installed in a pouch-shaped case made of an aluminum laminate. Among them, the pouch-shaped battery cells have the advantages of relatively large capacity and easy modification of the structure.

[0006] Various wearable computer technologies and applications using these secondary batteries as a power source are being developed and announced, and electronic devices such as mobile phones and laptop computers are being designed to have a predetermined curved surface to conform to ergonomic design. Therefore, secondary batteries for operating these electronic devices also need to be formed into a predetermined curved surface according to the shape of the electronic device.

[0007] When a bent battery cell formed with such a bent surface is repeatedly charged and discharged in a device that requires energy, deformation occurs. There is a need for a bent battery cell and a method for manufacturing the same that prevent this from happening and maintain the correct thickness and curvature to meet the specifications of the product.

[0008] Korean Patent Application Publication No. 10-2015-0092669 discloses a bent electrode assembly; a covering member configured to seal the electrode assembly; a bent reinforcing layer located on the covering member; and an adhesive layer configured to bond the reinforcing layer, wherein the bending strength of the reinforcing layer is greater than the volume expansion force of the bent secondary battery cell.

[0009] However, it is different from the present invention in that an internal support is formed on a specific surface of the electrode assembly in the pouch to prevent curvature change.

[0010] Korean Patent Application Publication No. 10-2013-0119664 discloses a bent electrode assembly; a pouch configured to seal the electrode assembly; a reinforcing portion continuously formed on a side surface of a main body portion of the pouch; and the area, width, and constant curvature characteristics of the reinforcing portion.

[0011] However, it is different from the present invention in that an internal support is formed on a surface of the electrode assembly in the pouch where a current collector for the electrode active material is not formed to prevent curvature change.

[0012] Korean Patent Application Publication No. 10-2003-0096718 discloses a pouch configured to accommodate an electrode assembly therein, the electrode assembly including a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, in which state at least a part of each electrode lead wire connected to the positive electrode plate and the negative electrode plate is exposed to the outside, and at least one reinforcing member attached to the whole or a part of the surface of the pouch, wherein the reinforcing member is a metal member.

[0013] However, it is different from the present invention in that an internal support having elastic resilience at high temperatures due to repeated charging and discharging of the bent battery cell is formed on a specific surface of the electrode assembly in a pouch configured to accommodate the bent battery cell to prevent curvature change.

[0014] Japanese Patent Application Publication No. 2002-251855 discloses a non-aqueous secondary battery, which is a battery having a battery element and a covering film configured to cover the battery cell element, the covering film having a moisture-proof layer and a synthetic resin layer, wherein edges of the covering film are bonded to each other in an overlapping state, and the joint of the covering film is folded backward so as to overlap each other, and thus four or more layers are stacked and pressed.

[0015] However, different from the present invention, an internal support made of a thermosetting material is formed on a specific surface of the electrode assembly in the pouch to prevent curvature change.

[0016] Therefore, there is a need to develop a flexible secondary battery and a method of manufacturing the same, which include an electrode support formed in an electrode assembly to prevent curvature change, deformation, asymmetry, non-uniform thickness of a flexible battery cell, and damage to the pouch and / or leads of the battery that may occur during charging and discharging of the flexible battery cell, such that the flexible battery cell can operate without damage in a device that requires energy.

[0017] (Prior Art Documents)

[0018] (Patent Document 1) Korean Patent Application Publication No. 10-2015-0092669

[0019] (Patent Document 2) Korean Patent Application Publication No. 10-2013-0119664

[0020] (Patent Document 3) Korean Patent Application Publication No. 10-2003-0096718

[0021] (Patent Document 4) Japanese Patent Application Publication No. 2002-251855 Summary of the Invention

[0022] Technical Problem

[0023] In view of the above problems, the present invention is made. A flexible battery cell produced by a flexible battery cell production jig has a circular shape with a specific curvature, and when the flexible battery cell is repeatedly charged and discharged in a device provided with the flexible battery cell, the flexible battery cell is deformed. An object of the present invention is to provide a flexible secondary battery and a method of manufacturing the same, which include an electrode support formed in an electrode assembly to prevent deformation of the flexible battery cell such that the flexible battery cell can operate without damage in a device that requires energy.

[0024] Technical Solution

[0025] To achieve the above object, a flexible secondary battery according to the present invention includes: a flexible electrode assembly 100 having a positive electrode / separator / negative electrode stacked structure; a battery cell case 200 configured to accommodate the electrode assembly therein; and a flexible internal support 300 formed on at least one surface of the electrode assembly.

[0026] The electrode assembly may be a stacked and folded type electrode assembly in which stacked single cells, dual cells, or full cells as unit cells are sequentially wound through separator sheets.

[0027] The internal support member may be formed on each of surfaces 110 and 120 of the current collector forming the electrode where the active material layer is not formed.

[0028] In addition, the internal support member may be formed on one or more longitudinal (y-direction) side surfaces 130 and 140 of the current collector of the electrode assembly.

[0029] The internal support member may be made of one or more selected from metals, ceramics, and polymer compounds.

[0030] The polymer compound may be a thermosetting polymer compound.

[0031] The thermosetting polymer compound may be one or more selected from polyamide (PA), polyarylene ether (PPE), polyether ether ketone (PEEK), polyimide (PI), and polytetrafluoroethylene (PTFE).

[0032] The internal support member may be formed on a part or the whole of the surface of the current collector or on the side surface of the current collector.

[0033] The thickness of the internal support member may decrease in the transverse direction from the center of the current collector.

[0034] The internal support member may have at least one support bar formed therein to extend in the transverse direction and the longitudinal direction by forming elastic resilience therein.

[0035] In addition, the present invention may provide various combinations of the above solutions.

[0036] Advantageous Effects

[0037] As is apparent from the above description, the shape of the bent secondary battery according to the present invention can be maintained even after repeated charging and discharging of the bent secondary battery.

[0038] In addition, the shape of the bent secondary battery unit can be maintained by the elastic internal support member in the electrode assembly even in a high-temperature environment due to charging and discharging.

[0039] Therefore, the present invention has the effect of preventing curvature change by strengthening vulnerable components formed when manufacturing the bent battery unit. Description of the Drawings

[0040] Figure 1 is a conceptual diagram of a bent secondary battery having a conventional reinforcing layer.

[0041] Figure 2 It is a perspective view of a flexible secondary battery having a conventional reinforcing layer.

[0042] Figure 3 It is a graph showing the change in the rate of curvature change and thickness change of a flexible secondary battery and a flexible secondary battery having a conventional reinforcing layer according to the number of charge and discharge cycles.

[0043] Figure 4 It is a view showing the deformation of a flexible secondary battery having a conventional reinforcing layer mounted in a device.

[0044] Figure 5 It is a cross-sectional view of an electrode assembly in which an internal support member according to an embodiment of the present invention is formed on the surface of a current collector.

[0045] Figure 6 It is a cross-sectional view of an electrode assembly in which an internal support member according to an embodiment of the present invention is formed on the side surface of a current collector.

[0046] Figure 7 It is a cross-sectional view of a flexible secondary battery in which an internal support member according to an embodiment of the present invention is formed on the surface of a current collector.

[0047] Figure 8 It is a cross-sectional view of a flexible secondary battery before disassembly in which an internal support member according to an embodiment of the present invention is formed on the surface of a current collector.

[0048] Figure 9 It is a cross-sectional view of a flexible secondary battery after disassembly in which an internal support member according to an embodiment of the present invention is formed on the surface of a current collector.

[0049] Figure 10 It is a cross-sectional view of a flexible secondary battery before and after disassembly in which an adhesive layer and an internal support member according to an embodiment of the present invention are formed on the surface of a current collector.

[0050] Figure 11 It is a view of an electrode assembly according to an embodiment of the present invention including an internal support member having a thickness change.

[0051] Figure 12 It is a perspective view of an electrode assembly according to an embodiment of the present invention including an internal support member containing support bars.

[0052] Figure 13 It is a cross-sectional view taken along line A - A' of an electrode assembly according to an embodiment of the present invention including an internal support member containing support bars.

[0053] Figure 14It is a cross-sectional view taken along line B-B' of an electrode assembly including an internal support member having a support rod according to an embodiment of the present invention. Detailed Embodiments

[0054] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those of ordinary skill in the art to which the present invention pertains can easily implement the preferred embodiments of the present invention. However, when describing in detail the working principles of the preferred embodiments of the present invention, if the detailed description of known functions and configurations incorporated herein may obscure the subject matter of the present invention, such detailed description will be omitted.

[0055] In addition, the same reference numerals will be used throughout the drawings to refer to components that perform similar functions or operations. In the case where a component is referred to as being connected to another component throughout the application, not only can one component be directly connected to another component, but also one component can be indirectly connected to another component through other components. In addition, unless otherwise specified, including a certain element does not mean excluding other elements, but means that these elements can be further included.

[0056] In addition, unless specifically restricted, the description of embodying an element by restriction or addition can be applied to all inventions without being limited to a specific invention.

[0057] In addition, in the specification and claims of the present application, unless otherwise specified, the singular form is intended to include the plural form.

[0058] In addition, in the specification and claims of the present application, unless otherwise specified, "or" includes "and". Therefore, "including A or B" refers to three cases, namely the case of including A, the case of including B, and the case of including both A and B.

[0059] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0060] For example, an electrode assembly can be manufactured by repeatedly stacking a positive electrode plate on which a positive electrode active material is applied, a negative electrode plate on which a negative electrode active material is applied, and a separator interposed between the positive electrode plate and the negative electrode plate.

[0061] An electrode assembly can be manufactured by winding a stack of a positive electrode plate, a separator, and a negative electrode plate in a jelly roll form.

[0062] The positive electrode plate may include a positive electrode active material portion on which a positive electrode active material is applied and a positive electrode uncoated portion on which no positive electrode active material is applied. The positive electrode active material may be a lithium-containing transition metal oxide such as LiCoO2, LiNiO2, LiMnO2, LiMnO4, or a lithium chalcogenide compound.

[0063] For example, a positive electrode active material portion can be formed by applying a positive electrode active material to a part of at least one surface of an aluminum plate, and the remaining portion of the aluminum plate to which the positive electrode active material is not applied can be a positive electrode uncoated portion.

[0064] The negative electrode plate can include a negative electrode active material portion to which a negative electrode active material is applied and a negative electrode uncoated portion to which the negative electrode active material is not applied. The negative electrode active material can be a carbon material such as crystalline carbon, amorphous carbon, carbon composite, or carbon fiber, lithium metal, or lithium alloy.

[0065] For example, a negative electrode active material portion can be formed by applying a negative electrode active material to a part of at least one surface of a copper plate, and the remaining portion of the copper plate to which the negative electrode active material is not applied can be a negative electrode uncoated portion.

[0066] For example, a separator can be manufactured by coating a polyvinylidene fluoride - hexafluoropropylene copolymer (PVDF - HFP co - polymer) on any one substrate selected from the group consisting of polyethylene (PE), polystyrene (PS), polypropylene (PP), and a copolymer of polyethylene (PE) and polypropylene (PP).

[0067] The first electrode tab and the second electrode tab are attached to the electrode assembly. Specifically, the first electrode tab and the second electrode tab 134 are respectively attached to the positive electrode uncoated portion and the negative electrode uncoated portion, and the first electrode tab and the second electrode tab can extend outward through the pouch.

[0068] The pouch seals the electrode assembly and houses the electrolyte together with the electrode assembly therein. For example, the pouch can have a three - layer structure of an insulating layer, a metal layer, and an insulating layer. For example, the metal layer can be made of materials such as aluminum, steel, stainless steel, etc., and the insulating layer can be made of materials such as modified polypropylene (CPP), polyethylene terephthalate (PET), nylon, etc.; however, the present invention is not limited thereto.

[0069] The pouch can include a pair of wings formed by thermal bonding. The pouch can include a receiving portion forming its first surface and a covering portion forming its second surface. A receiving space for receiving the electrode assembly is formed in the receiving portion, and when the electrode assembly is received in the receiving space, the covering portion connected to the receiving portion on one side is folded over the receiving portion, and then the receiving portion and the covering portion are thermally bonded to each other at the edge of the receiving space. Thus, the electrode assembly can be sealed, and the edge where the receiving portion and the covering portion are bonded to each other forms a pair of wings. The pair of wings can be bent parallel to the side surface of the curved secondary battery.

[0070] The bent battery cell has a shape bent through a forming process to have a predetermined radius of curvature R. That is, the bent battery cell can have a predetermined bent surface to correspond to the shape of the electronic device in which the bent battery cell is installed, thereby eliminating the gap between the electronic device and the bent battery cell, effectively utilizing the internal space of the electronic device, and preventing damage to the bent battery cell when the bent battery cell moves in the electronic device.

[0071] In addition, when the radius of curvature R of the bent battery cell decreases, the pressure applied to the bent battery cell during the forming process must increase. If the pressure increases, stress concentration regions may be formed in the compressed bent battery cell, and deformations such as twisting of the bent battery cell may occur. However, in the present invention, the stress generated in the bent battery cell can be minimized by applying the minimum pressure through two forming processes, and a bent battery cell with a smaller radius of curvature R of 50R or less can be manufactured.

[0072] (Comparative Example)

[0073] Figure 1 is a conceptual diagram of a bent secondary battery having a conventional reinforcing layer.

[0074] Figure 2 is a perspective view of a bent secondary battery having a conventional reinforcing layer.

[0075] The bent secondary battery can have a shape bent to have a predetermined radius of curvature R. That is, the bent secondary battery can have a predetermined bent surface to correspond to the shape of the electronic device in which the bent secondary battery is installed, thereby eliminating the space between the electronic device and the bent secondary battery and effectively utilizing the internal space of the electronic device.

[0076] Figure 1 and Figure 2 The bent secondary battery of can include: an electrode assembly; a pouch having a first covering member and a second covering member configured to seal the electrode assembly; and a reinforcing layer attached to the first covering member.

[0077] Figure 3 is a graph showing the change in the rate of curvature change and thickness change of a bent secondary battery and a bent secondary battery having a conventional reinforcing layer according to the number of charge and discharge cycles.

[0078] The rate of curvature change and thickness change of a bent secondary battery having a conventional reinforcing layer formed outside the pouch and a bent secondary battery without any auxiliary members were measured according to the number of charge and discharge cycles.

[0079] Referring to Figure 3It can be seen that for the first 100 cycles, the curvature change rates of the flexible secondary battery with the reinforcing layer and the flexible secondary battery without the auxiliary member are almost the same, and the curvature change rate increases to 7%.

[0080] It can be seen that after 100 cycles, the curvature change rates of the flexible secondary battery with the reinforcing layer and the flexible secondary battery without the auxiliary member slightly increase to 10%.

[0081] Thus, the effect of reducing the curvature change rate of the flexible secondary battery with the reinforcing layer is negligible.

[0082] Refer to Figure 3 It can be seen that for the first 100 cycles, the curvature change rates of the flexible secondary battery with the reinforcing layer and the flexible secondary battery without the auxiliary member are almost the same, and the thickness change increases to 5%.

[0083] It can be seen that after 100 cycles, the thickness changes of the flexible secondary battery with the reinforcing layer and the flexible secondary battery without the auxiliary member slightly increase to 6%.

[0084] Thus, the effect of reducing the thickness change of the flexible secondary battery with the reinforcing layer is negligible.

[0085] Figure 4 is a view showing the deformation of a flexible secondary battery with a conventional reinforcing layer installed in a device.

[0086] It can be seen that when a conventional flexible secondary battery having a reinforcing layer formed on the outside of the pouch is assembled into a device that requires energy, after charging and discharging the flexible secondary battery, the flexible secondary battery with the reinforcing layer becomes loose.

[0087] Figure 5 is a cross-sectional view of an electrode assembly in which an internal support according to an embodiment of the present invention is formed on the surface of a current collector.

[0088] The flexible secondary battery may include: a flexible electrode assembly 100 having a positive electrode / separator / negative electrode stacked structure; a battery cell case 200 configured to accommodate the electrode assembly therein; and a flexible internal support 300 formed on at least one surface of the electrode assembly.

[0089] The electrode assembly may include a separator between electrode plates that are preferably current collectors, and the electrode plates have a positive electrode active material formed thereon for forming a positive electrode and a negative electrode active material for forming a negative electrode.

[0090] In one example, the electrode assembly may be configured such that the positive electrode plate, the separator, and the negative electrode plate are stacked in sequence.

[0091] In addition, the electrode assembly can be wound around a winding axis to have a jelly-roll structure.

[0092] In addition, the electrode assembly can be bent in a direction perpendicular to the longitudinal direction, so that the central axis of the stack can have a bent shape. Thus, the electrode assembly can include a first concave surface S1 and a second convex surface S2 opposite to the first concave surface S1.

[0093] In addition, the electrode assembly can be a stacked and folded type electrode assembly in which a stacked single cell, dual cell or full cell as a unit cell is sequentially wound through a separator sheet.

[0094] The basic unit of an electrochemical cell unit is a single cell, a full cell or a bicell.

[0095] The single cell can be configured to have a double-sided electrode plate structure in which an electrode active material is applied to two surfaces of a current collector. Since the single cell has a double-sided electrode plate structure rather than a structure in which a separator and an electrode plate are stacked, the single cell is easy to handle during processing.

[0096] As an electrode assembly having an advanced structure with a hybrid jelly-roll type electrode assembly and a stacked type electrode assembly, it can be a stacked and folded type electrode assembly having a structure of a full cell having a positive electrode / separator / negative electrode structure with a certain unit size or a bicell having a structure of a positive electrode (negative electrode) / separator / negative electrode (positive electrode) / separator / positive electrode (negative electrode) structure folded using a long separator.

[0097] The properties of a full cell or a bicell mainly depend on the electrodes, electrolytes and other materials used. Among them, the amount of active material introduced into the electrodes is related to the maximum number of lithium ions that can be finally combined. Therefore, the more the amount of active material, the larger the capacity of the battery. Therefore, if the adhesiveness of the binder is high and the amount of the introduced binder is reduced, an electrode with a large amount of active material can be manufactured. Therefore, a binder with excellent adhesiveness needs to be provided.

[0098] Figure 6 It is a cross-sectional view of an electrode assembly in which an internal support according to an embodiment of the present invention is formed on a side surface of a current collector.

[0099] In addition, the internal support can be formed on surfaces 110 and 120 of the current collector forming the electrode where no active material layer is formed.

[0100] The surface of the current collector can be the uppermost electrode of an electrode assembly including a plurality of stacked electrodes.

[0101] The electrode can be a negative electrode and / or a positive electrode.

[0102] In addition, the internal support can be formed on one or more longitudinal (y-direction) side surfaces 130 and 140 of the current collector of the electrode assembly.

[0103] Accordingly, the internal support can be adjacent to the side surfaces of the stacked multiple electrodes and separators.

[0104] The internal support can be formed to surround the side surfaces of the stacked multiple electrodes and separators.

[0105] The internal support can be formed to surround the entire side surface and a partial surface of the electrode current collector.

[0106] The internal support body can be in the form of a bracket.

[0107] Figure 7 is a cross-sectional view of a flexible secondary battery in which an internal support according to an embodiment of the present invention is formed on the surface of a current collector.

[0108] Figure 8 is a cross-sectional view of a flexible secondary battery before disassembly in which an internal support according to an embodiment of the present invention is formed on the surface of a current collector.

[0109] In addition, the internal support can be made of one or more selected from metals, ceramics, and polymer compounds.

[0110] In addition, the polymer compound can be a thermosetting polymer compound.

[0111] In addition, the thermosetting polymer compound can be one or more selected from polyamide (PA), polyarylene ether (PPE), polyether ether ketone (PEEK), polyimide (PI), and polytetrafluoroethylene (PTFE).

[0112] Figure 9 is a cross-sectional view of a flexible secondary battery after disassembly in which an internal support according to an embodiment of the present invention is formed on the surface of a current collector. In addition, an adhesive layer can be formed between the internal support and the surface of the current collector or the side surface of the current collector.

[0113] In addition, the adhesive layer can be one or more selected from epoxy resin, silicone, polyurethane, polyamide, Teflon, and ceramic adhesives.

[0114] Figure 10FIG. 0 is a cross-sectional view before and after disassembly of a flexible secondary battery in which an adhesive layer and an internal support according to an embodiment of the present invention are formed on a surface of a current collector.

[0115] In addition, the internal support may be formed on a part or the whole of the surface of the current collector, or on a side surface of the current collector.

[0116] Figure 11 FIG. 7 is a view of an electrode assembly including an internal support having a thickness variation according to an embodiment of the present invention.

[0117] In addition, the thickness of the internal support may decrease from the center of the current collector in a lateral direction.

[0118] Figure 12 FIG. 14 is a perspective view of an electrode assembly including an internal support having a support bar according to an embodiment of the present invention.

[0119] In addition, the internal support may have at least one support bar formed therein to have elastic resilience so as to extend in a lateral direction and a longitudinal direction.

[0120] Damage to the flexible secondary battery cell can be prevented when the flexible secondary battery cell moves in an electronic device.

[0121] Figure 13 FIG. 24 is a cross-sectional view taken along line A-A' of an electrode assembly including an internal support having a support bar according to an embodiment of the present invention.

[0122] Figure 14 FIG. 28 is a cross-sectional view taken along line B-B' of an electrode assembly including an internal support having a support bar according to an embodiment of the present invention.

[0123] The cross-sectional shape of the support bar may be any one of a circle, a triangle, a quadrilateral, and a shape.

[0124] At least one support bar may be formed in the internal support adjacent to the surface of the current collector or the side surface of the current collector.

[0125] The internal support may be provided therein with one or more support bars having different lengths and having elastic resilience.

[0126] The internal support may be provided therein with one or more support bars having different thicknesses and having elastic resilience.

[0127] The support bar may be made of at least one of a metal, a polymer material, and a ceramic component.

[0128] The elastic resilience of the support bar may be greater than or equal to the elastic resilience of the internal support, and the support bar and the internal support may be made of the same material.

[0129] Those skilled in the art to which the present invention pertains will understand that, based on the above description, various applications and modifications can be made within the scope of the present invention.

[0130] (Description of reference signs)

[0131] 100: Bent secondary battery cell

[0132] 110: Electrode assembly

[0133] 120, 220: Pouch

[0134] 122: Pouch cup portion

[0135] 124: Pouch covering portion

[0136] 132: Electrode tab

[0137] 140: Reinforcing layer

[0138] 200: Tool

[0139] 210: Loosening

[0140] 300: Internal support

[0141] 310: Support rod

[0142] 400: Adhesive layer

Claims

1. A curved secondary battery, comprising: A curved electrode assembly having a positive electrode / separator / negative electrode stacking structure; a battery cell case configured to accommodate the electrode assembly therein; and A curved inner support is formed on at least one surface of the electrode assembly. 2 . The curved secondary battery according to claim 1 , wherein the electrode assembly is a stacked and folded type electrode assembly in which a stacked type single cell, a bi-cell, or a full cell as a unit cell is sequentially wound through a separator sheet. 3 . The curved secondary battery according to claim 1 , wherein the internal support member is formed on a surface of a current collector forming the electrode on which an active material layer is not formed. 4 . The curved secondary battery of claim 1 , wherein the internal support is formed on one or more longitudinal (y-direction) side surfaces of a current collector of the electrode assembly. 5 . The curved secondary battery according to claim 3 , wherein the inner support member is made of one or more selected from metals, ceramics, and polymer compounds. 6 . The curved secondary battery according to claim 5 , wherein the polymer compound is a thermosetting polymer compound. 7 . The curved secondary battery according to claim 6 , wherein the thermosetting polymer compound is one or more selected from the group consisting of polyamide (PA), polyarylene ether (PPE), polyetheretherketone (PEEK), polyimide (PI) and polytetrafluoroethylene (PTFE). 8 . The curved secondary battery according to claim 3 , wherein an adhesive layer is formed between the inner support and the surface of the current collector or the side surface of the current collector. 9 . The curved secondary battery according to claim 8 , wherein the adhesive layer is one or more selected from epoxy resin, silicone, polyurethane, polyamide, Teflon, and ceramic adhesives. 10 . The curved secondary battery according to claim 3 , wherein the internal support is formed on a portion or the entirety of the surface of the current collector or the side surface of the current collector. 11 . The curved secondary battery according to claim 3 or 4 , wherein a thickness of the inner support member decreases in a lateral direction from a center of the current collector. 12 . The curved secondary battery according to claim 3 , wherein the inner support member has at least one support bar in which an elastic resilience is formed so as to extend in a lateral direction and a longitudinal direction.

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