Battery and battery case

Abstract

An exterior material for a battery includes a barrier layer; a first functional layer formed on one surface of the barrier layer; a second functional layer formed on the other surface of the barrier layer; and an Anti-Corrosion layer formed on at least one surface of the barrier layer, the first functional layer is composed of one or more resin layers including a sealing layer, the second functional layer is thicker than the thickness of the barrier layer, and has a thickness of 33% or more of the total thickness of the exterior material.

Description

Technical Field

[0001] This invention relates to an outer casing material and a battery utilizing the outer casing material. Background Technology

[0002] An electrochemical cell is a component that can provide electrical energy by consisting of at least two electrodes and an electrolyte. In particular, lithium-ion batteries, which are composed of rechargeable and dischargeable secondary cells, are widely used in various advanced electronic devices, including smartphones.

[0003] Recently, in designing mobile devices, including smartphones, and various wearable devices, there has been an increasing trend towards designs that deviate from traditional shapes. Consequently, there is growing interest in flexible devices that can bend while maintaining functionality. Therefore, ensuring the functionality and safety of flexible electrochemical batteries embedded in such flexible devices and used as power sources is of paramount importance.

[0004] Repeated bending and unfolding of flexible batteries poses a risk of damaging the outer casing. Severe damage to the casing can lead to leakage of the internal electrolyte. Furthermore, even minor damage to the casing allows moisture from the air to penetrate the battery, causing swelling and damaging the electrodes, thereby reducing the battery's capacity and output.

[0005] Therefore, in order to prevent damage to the outer casing material of the flexible battery by absorbing the compressive and tensile stresses generated in the bent portion of the battery, the outer casing material is patterned by applying pressure to the upper and lower molds. Because the initial elastic modulus (initial elastic modulus) of the patterned outer casing material is increased, the forces acting on the outer casing material are dispersed rather than concentrated on one side when the battery bends. Thus, the outer casing material and the internally housed electrode assembly do not suffer severe bending in any one part.

[0006] In addition, the pattern of the outer material does not need to be deep, but it needs to minimize the damage to the outer material caused by repeated bending, folding, twisting and other actions of the battery, thereby improving the battery's durability.

[0007] However, by patterning the outer material to prevent bending of the outer material and the electrode assembly housed inside the outer material, damage to the outer material can be minimized, but the edge of the patterned portion of the outer material adjacent to the sealed portion and the patterned portion is damaged.

[0008] In this case, when the battery is deformed, the parts with a large radius of curvature are almost undamaged, but the outer material with a relatively small radius of curvature, such as the edge of the pattern, is damaged, as are the pin holes and other outer material defects.

[0009] Therefore, in order to prevent damage to the edges of the patterned outer material, it is necessary to develop outer materials with high durability that improve the durability of flexible batteries and are different from those of ordinary batteries.

[0010] Patent Document 1: Korean Patent Publication No. 2005-0052069 (published on June 2, 2005)

[0011] Patent Document 2: Japanese Patent Publication No. 2013-218991 (published on October 24, 2013) Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] The present invention addresses the problems of the prior art as described above by providing an outer casing material comprising: a barrier layer; a first functional layer formed on one surface of the barrier layer; a second functional layer formed on another surface of the barrier layer; and an anti-corrosion layer formed on at least one surface of the barrier layer, wherein the first functional layer is composed of one or more resin layers including a sealing layer, and the second functional layer is thicker than the barrier layer and has a thickness of 33% or more of the total thickness of the outer casing material.

[0014] The present invention provides a battery comprising: an outer casing material including a barrier layer, a first functional layer, a second functional layer, and an anti-corrosion layer, wherein the first functional layer is formed on one surface of the barrier layer, the second functional layer is formed on another surface of the barrier layer, and the anti-corrosion layer is formed on at least one surface of the barrier layer; an electrode assembly inserted between the outer casing materials; and a sealing portion for sealing the electrode assembly in the outer casing material, wherein the first functional layer is composed of one or more resin layers including the sealing layer, and the second functional layer is thicker than the barrier layer and has a thickness of 33% or more of the total thickness of the outer casing material.

[0015] The present invention provides a method for preparing a battery using an outer casing material, wherein the first functional layer of the outer casing material further includes a reinforcing resin layer with a melting point higher than that of the sealing layer, and the formation of a non-uniform layer is suppressed by forming the reinforcing resin layer between the anti-corrosion layer and the sealing layer, wherein the non-uniform layer is generated around the sealing portion of the outer casing material.

[0016] One object of the present invention is to provide an outer casing material and a battery utilizing the outer casing material, which prevents damage occurring at the patterned edges and around the seal of the outer casing material, wherein the second functional layer is thicker than the barrier layer in order to improve the durability against battery deformation.

[0017] However, the technical problem to be solved in this embodiment is not limited to the technical problem described above, and other technical problems may also exist.

[0018] Solution for solving the problem

[0019] As a solution to the technical problems described above, one embodiment of the present invention provides an outer casing material for a battery, the outer casing material comprising: a barrier layer; a first functional layer formed on one surface of the barrier layer; a second functional layer formed on another surface of the barrier layer; and an anti-corrosion layer formed on at least one surface of the barrier layer, wherein the first functional layer is composed of one or more resin layers including a sealing layer, and the second functional layer is thicker than the barrier layer and has a thickness of 33% or more of the total thickness of the outer casing material.

[0020] In one embodiment, the barrier layer has a thickness of 25 μm or more, and the total thickness of the outer material can be from 100 μm to 300 μm.

[0021] In one embodiment, when the outer material is folded in such a way that the second functional layer is located inside, the radius of curvature of the folded barrier layer can be 0.03 mm or more.

[0022] In one embodiment, the sealing layer is thicker than or equal to the thickness of the barrier layer, and may have a thickness of 25 μm or more.

[0023] In one embodiment, the first functional layer further includes a reinforcing resin layer, the reinforcing resin layer having a higher melting point than the sealing layer, the reinforcing resin layer being thicker than the anti-corrosion layer, and having a thickness of 10 μm or more.

[0024] In one embodiment, the reinforcing resin layer may have a thickness of 0.25 to 4.2 times that of the sealing layer.

[0025] In one embodiment, the aforementioned outer material can be used in a flexible battery with bendability.

[0026] Another embodiment of the present invention provides a battery utilizing an outer casing material, the battery comprising: an outer casing material including a barrier layer, a first functional layer, a second functional layer, and an anti-corrosion layer, wherein the first functional layer is formed on one surface of the barrier layer, the second functional layer is formed on another surface of the barrier layer, and the anti-corrosion layer is formed on at least one surface of the barrier layer; an electrode assembly inserted between the outer casing materials; and a sealing portion for sealing the electrode assembly in the outer casing material, wherein the first functional layer is composed of one or more resin layers including the sealing layer, and the second functional layer is thicker than the barrier layer and has a thickness of 33% or more of the total thickness of the outer casing material.

[0027] Invention Effects

[0028] According to one of the aforementioned technical solutions of the present invention for solving the problem, the present invention can provide an outer casing material comprising a barrier layer; a first functional layer formed on one surface of the barrier layer; a second functional layer formed on another surface of the barrier layer; and an anti-corrosion layer formed on at least one surface of the barrier layer, wherein the first functional layer is composed of one or more resin layers including a sealing layer, and the second functional layer is thicker than the barrier layer and has a thickness of 33% or more of the total thickness of the outer casing material.

[0029] Furthermore, taking into account the radius of curvature of the barrier layer in the outer material, the second functional layer of the outer material is made thicker than the barrier layer. This prevents damage to the sealing portion of the outer material and the pattern edge portion of the outer material, which is adjacent to the pattern portion.

[0030] Furthermore, the first functional layer of the outer casing also includes a reinforcing resin layer, which increases the radius of curvature of the barrier layer and reduces the thickness of the uneven layer generated around the seal of the outer casing, thereby improving the bending durability of the battery.

[0031] Furthermore, it prevents damage to the outer casing and leakage of the electrolyte, thereby improving the safety and durability of the battery. Attached Figure Description

[0032] Figure 1a An illustrative diagram showing a battery including an outer casing material according to an embodiment of the present invention is provided. Figure 1b An illustrative diagram showing the cross-sectional shape of a battery according to an embodiment of the present invention.

[0033] Figures 2a to 2c An illustrative diagram is provided to show an embodiment of the exterior material of the present invention, which is composed of a multi-layered structure.

[0034] Figure 3a and Figure 3b This is an illustrative diagram illustrating the process of sealing two outer packaging materials according to an embodiment of the present invention.

[0035] Figure 4 An illustrative diagram illustrating the characteristics of an outer casing material and a battery with a multi-layered structure, according to an embodiment of the present invention, for comparative evaluation.

[0036] Figure 5a and Figure 5b This is an illustrative diagram used to illustrate an embodiment of the present invention, showing the radius of curvature of the barrier layer of the outer casing material based on the thickness of the second functional layer and the folding evaluation of the outer casing material.

[0037] Figure 6 This diagram illustrates an example of comparing and evaluating the durability of an outer casing material based on the thickness of a second functional layer through a folding evaluation of an outer casing material composed of a multi-layered structure according to an embodiment of the present invention.

[0038] Figure 7 This is a flowchart of a method for preparing a battery using an external material according to an embodiment of the present invention. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement the embodiments of the present invention. However, the present invention can be implemented by various different methods and is not limited to the embodiments described herein. Furthermore, in the accompanying drawings, parts unrelated to the description have been omitted for clarity, and similar reference numerals have been used for similar parts throughout the specification.

[0040] Throughout the specification, when a part is referred to as "including" a component, other components may be included, rather than excluded, unless specifically stated otherwise. Furthermore, throughout the specification, when a part is referred to as "connected" to another part, this includes not only direct connections but also connections with other components in between, and electrical connections through other components. Moreover, throughout the specification, when a component is referred to as being "on" another component, this includes not only cases where the component is in contact with the other component but also cases where other components exist between the two components.

[0041] The battery of the present invention, including the outer casing, can be, for example, an electrochemical battery or a lithium-ion battery. Specifically, the battery of the present invention, including the outer casing, can be configured such that the electrode assembly and the electrolyte are contained and sealed inside the outer casing, thereby charging and discharging through the movement of lithium ions. The battery of the present invention, including the outer casing, can be a flexible battery, which can be configured to be flexible and bendable while maintaining its functional state. Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

[0042] Figure 1a To illustrate a perspective view of a battery including an outer casing material 100 according to an embodiment of the present invention, Figure 1b To show Figure 1a The diagram shows the cross-sectional shape of the battery.

[0043] Reference Figure 1a and Figure 1b The battery 1 may include: an outer casing 100; an electrode assembly 200 housed inside the outer casing 100; and an electrode lead 300 connected to the electrode assembly 200.

[0044] For example, the outer material 100 can be formed in a multilayer structure by laminating multiple functional materials. Each of the multiple functional materials can have toughness.

[0045] For example, the multi-layer structure of the outer material 100 may include a first functional layer, a barrier layer, a second functional layer, and an anti-corrosion layer, which are distinguished according to the function of each layer.

[0046] The first functional layer consists of one or more resin layers including a sealing layer. The sealing layer is a material that melts at the lowest temperature among a plurality of functional materials of the outer material 100. It performs the function of sealing the electrode assembly 200 inside and preventing electrolyte leakage to the outside by heating. For example, it may be made of polypropylene (PP) film.

[0047] The barrier layer is a crystalline metal layer, for example, it can be made of aluminum foil, and is used to block the movement of matter in the amorphous regions of the sealing layer of the polymer film material from the source.

[0048] The second functional layer is a layer used to prevent contamination and damage to the metal layer that constitutes the barrier layer. For example, it may be composed of a nylon film or a composite layer of nylon and polyethylene terephthalate (PET).

[0049] The anti-corrosion layer can prevent the electrolyte in the outer material 100 from reacting with the barrier layer.

[0050] The outer material 100 is manufactured using a roll-to-roll process, and its mechanical properties can vary depending on whether the roller is in the axial or longitudinal direction. The transverse direction (TD) refers to the axial direction of the roller, while the machine direction (MD) refers to the longitudinal direction of the roller.

[0051] This outer material 100 can be used in flexible batteries 1 that are flexible.

[0052] In the outer casing material 100 used for the flexible battery 1, the mechanical properties of the battery vary depending on the direction in which the pattern is formed. That is, batteries with outer casing materials in which the pattern is formed along the TD direction of the outer casing material and batteries with outer casing materials in which the pattern is formed along the MD direction of the outer casing material may have different mechanical properties. Thus, the direction in which the pattern is formed can affect the durability of the flexible battery 1.

[0053] The electrode assembly 200 has a plurality of electrodes and may also include a separation membrane, which can be formed in a structure in which the plurality of electrodes and the separation membrane are stacked along the thickness direction.

[0054] The electrode assembly 200 may include a first electrode and a second electrode with different polarities. A mixture containing active materials may be coated on both sides or one side of the first and second electrodes, respectively. A separation membrane may be disposed between the first and second electrodes. For example, the first electrode may be a negative electrode, and the current collector used may be made of copper, aluminum, etc., or may be made of graphite, carbon, lithium, silicon, SiO2, etc. x The negative electrode active material is composed of one or more combinations of silicon derivatives, silicon-graphite composites, tin, and silicon-tin composites. Furthermore, the second electrode is the positive electrode, and the current collector used is made of materials such as aluminum or stainless steel. It can be made of one or more combinations of positive electrode active materials such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt manganese oxide, lithium cobalt nickel oxide, lithium manganese nickel oxide, lithium cobalt nickel manganese oxide, lithium cobalt nickel aluminum oxide, and lithium iron phosphate. In the electrode assembly 200, the length direction of the two directions in which the first and second electrodes extend as forming surfaces is longer than the width direction, and it can have a thin shape along a direction intersecting (e.g., orthogonal) to the direction of the forming surfaces, i.e., the thickness direction of the stacked active material and the separation membrane.

[0055] Furthermore, the electrode assembly 200 may include electrode connecting tabs and lead connecting tabs. The electrode connecting tabs can be formed such that one end of the first electrode and the second electrode protrudes along their length, and electrode connecting tabs protruding in electrodes of the same polarity can be combined. The electrodes can be electrically connected in parallel via the electrode connecting tabs. The lead connecting tabs are connected to the electrode leads 300 and can protrude in the positive and negative electrodes to combine with the electrode leads 300.

[0056] Specifically, the outer casing 100 may include a receiving portion 110 and a sealing portion 120. The receiving portion 110 forms a space for receiving the electrode assembly 200, and the sealing portion 120 is capable of engaging in a manner that seals the received electrode assembly 200 from the outside. Figure 1bAs shown, the receiving portion 110 can correspond to the areas of two outer materials 100 that are spaced apart from each other and facing each other. In order to form the receiving portion 110, the outer materials 100 can be processed in a way that presses and protrudes along the thickness direction, so that the predetermined area of ​​the outer materials 100 is approximately in the shape of a quadrilateral bowl (or cup).

[0057] More specifically, in this embodiment, at least one patterned portion 115 may be formed on the surface of the receiving portion 110 extending along the TD of the outer material 100. For example, when a battery is manufactured in a manner that includes an outer material 100 with the patterned portion 115 formed thereon, the width direction 10A of the battery may be the TD of the outer material 100, and the length direction 10B of the battery may be the MD of the outer material 100.

[0058] The pattern portion 115 is a pattern that is repeated in a direction extending along one direction and intersecting another direction. Specifically, it can have a raised or recessed shape along one direction by alternately protruding or recessing along the thickness direction (i.e., alternately protruding in opposite directions). For example, the pattern portion 115 can be formed in a manner that repeats the raised or recessed shape having a predetermined pattern height h1 and pattern spacing P. One direction can be the width direction 10A of the battery TD, which serves as the outer casing material 100, and the direction in which the pattern portion 115 repeats can be the length direction 10B of the battery. Figure 1b As shown, the outer material 100 forming the receiving portion 110 can form a corrugated or pleated pattern along the length direction through the protruding and recessed pattern portions 115.

[0059] Alternatively, the patterned portion 115 may also be formed extending along the MD of the outer material 100 in a direction different from the TD. For example, when a battery is manufactured in a manner that includes an outer material in which the patterned portion 115 is formed, the width direction 10A of the battery may be the MD of the outer material, and the length direction 10B of the battery may be the TD of the outer material.

[0060] The sealing portion 120 is formed by joining two sealing layers (sealing surfaces). The sealing layer (sealing surface) refers to the thermally bonded surface of the outer material 100. The two sealing layers (sealing surfaces) folded along the edge of the receiving portion 110 are joined together, thereby isolating the internal space (receiving portion 110) from the outside. The internal space can accommodate the previously described electrode assembly 200 and electrolyte, and the electrode assembly 200 and electrolyte can be kept in a sealed state.

[0061] Furthermore, the sealing portion 120 may be in the shape of a flat plate extending along the width direction 10A or the length direction 10B of the battery. For example, the flat plate shape of the sealing portion 120 may be a shape that is not curved in a manner where the surfaces face each other. Alternatively, the sealing portion 120 may have a pattern different from the patterned portion 115; for example, the sealing portion 120 may have a pattern that is lower in height than the patterned portion 115 along the thickness direction.

[0062] Furthermore, the electrode leads 300 are connected to the lead connectors of the electrode assembly 200 inside the outer casing 100 and extend to the outside of the outer casing 100. The electrode leads 300 can serve as terminals for electrical connection with the electrode assembly 200 housed inside the outer casing 100, and when the sealing portion 120 is formed, they can penetrate the sealing portion 120 in a manner disposed between sealing layers (sealing surfaces) through engagement. A pair of positive and negative electrode leads 300 can be coupled to lead connectors of the same polarity disposed on the electrode assembly 200.

[0063] Figures 2a to 2c An illustrative diagram is provided to show an embodiment of the exterior material of the present invention, which is composed of a multi-layered structure.

[0064] Figure 2a This diagram illustrates an existing multi-layered exterior material. The existing exterior material 210 includes a sealing layer 211, a barrier layer 212, and a protective layer 213. The exterior material 210 also includes an adhesive layer 214 between the layers, which can be located between the layers to bond and stack the layers constituting the exterior material 210. (See reference...) Figure 2a In the existing outer material 210, the sealing layer 211 and the barrier layer 212 account for a high proportion of the total thickness of the outer material 210.

[0065] Specifically, the sealing layer 211 of the existing outer casing material 210 is configured to have a thickness of approximately 35 to 53% of the total thickness of the outer casing material 210. The existing sealing layer 211 extends during the cup forming process and assists in the extension of the metal layer constituting the barrier layer 212. To prevent the metal layer from being exposed to the electrolyte, the sealing layer 211 is configured to be the thickest part of the total thickness of the existing outer casing material 210. In particular, when conventional lithium batteries are manufactured in large-scale (e.g., batteries for electric vehicles) configurations, the existing sealing layer 211 is configured to be approximately twice as thick as the sealing layer 211 used in smaller batteries.

[0066] In the case of a flexible battery prepared using this existing outer material 210, if heat is applied to the sealing layer 211 to seal it, the thickness of the sealing portion is rapidly reduced (by more than half). As a result, the bending durability in the pattern edge portion of the part adjacent to the sealing portion of the flexible battery and with a small radius of curvature is reduced.

[0067] The existing barrier layer 212 is configured to have a thickness of approximately 25-40% of the total thickness of the outer material 210. The existing barrier layer 212 utilizes metal foil to completely block the movement of substances, but metal foil has the disadvantage of insufficient toughness compared to other constituent materials. To improve the moisture barrier properties and forming properties of this existing barrier layer 212, the thickness of the barrier layer 212 is made to maintain a specified level above a certain level, thereby preventing the metal layer from tearing or developing pinholes even when extended during cup processing.

[0068] The existing protective layer 213 is configured to have a thickness of approximately 15 to 25% of the total thickness of the existing outer casing material 210. The existing protective layer 213 performs the function of the protective barrier layer 212 and is configured to be relatively thin compared to other layers in the total thickness of the existing outer casing material 210 in order to prevent a reduction in the energy density of the flexible battery.

[0069] Figure 2b This diagram illustrates an example of an exterior material comprising a multilayer structure including a first functional layer with a sealing layer, a barrier layer, a second functional layer, and an anti-corrosion layer, according to an embodiment of the present invention. (Refer to...) Figure 2b The outer casing material 100 may include a first functional layer 220, an anti-corrosion layer 270, a barrier layer 230, and a second functional layer 240. The outer casing material 100 also includes an adhesive layer 260 between the layers, which may be located between the layers to bond and stack the layers constituting the outer casing material 100.

[0070] The total thickness of the outer material 100 can be configured from 100μm to 300μm.

[0071] A first functional layer 220 is formed on one surface of the barrier layer 230 and may be composed of one or more resin layers including a sealing layer. For example, the sealing layer may be configured to have a thickness of about 30 to 60% of the total thickness of the outer material 100. For example, the sealing layer may be thicker than the barrier layer 230, for example, it may have a thickness of 25 μm or more. The sealing layer provides the function of protecting the barrier layer 230. Furthermore, in order to improve the bending durability of the outer material 100, the sealing layer may be configured to be thicker so that when the outer material 100 is bent, the radius of curvature of the barrier layer 230 increases and it can be bent.

[0072] The anti-corrosion layer 270 may be laminated on the first functional layer 220. The anti-corrosion layer 270 performs the function of preventing the electrolyte in the outer casing material 100 from reacting with the barrier layer 230, and the anti-corrosion layer 270 may be configured to have a thickness of about 3 to 6 μm including the adhesive layer 260.

[0073] The barrier layer 230 is laminated on the anti-corrosion layer 270, and for example, it can be configured to have a thickness of about 8 to 30% of the total thickness of the outer casing material 100. For example, the barrier layer 230 can have a thickness of 25 μm or more.

[0074] exist Figure 2a In the existing outer material 210, the barrier layer 212 is equivalent to the layer with the weakest durability under repeated bending. It has the following disadvantages: the thicker the existing barrier layer 212, the weaker its durability; the thinner the existing barrier layer 212, the worse the pattern processing of the surface of the outer material 210. Therefore, the existing barrier layer 212 is required to have an appropriate thickness.

[0075] However, this application provides the following advantages: compared with the barrier layer 230, the thickness ratio of the second functional layer 240 is increased, thereby improving the repeated bending durability, one of the evaluation indicators of the flexibility of the flexible battery 1.

[0076] In the case of flexible battery 1, this barrier layer 230 is formed within a maximum of 2 mm, which is not as deep as in existing batteries. Therefore, it is acceptable to make it relatively thin compared to other layers if the barrier function can be performed accurately.

[0077] The second functional layer 240 is formed on the other surface of the barrier layer 230, and may be configured to have a thickness of about 22 to 50% of the total thickness of the outer material 100. For example, the second functional layer 240 is thicker than the barrier layer 230 and may have a thickness of more than 33% of the total thickness of the outer material 100.

[0078] The second functional layer 240 provides the function of protecting the barrier layer 230 from the influence of the external environment.

[0079] To improve the bending durability of the outer material 100, the second functional layer 240 may be configured to be as thick as possible so that when the outer material 100 is bent, the radius of curvature of the barrier layer 230 increases and it can be bent.

[0080] In the flexible battery 1, the patterned portion 115 of the outer material 100 with the smallest radius of curvature R and the patterned edge adjacent to the sealing portion 120 are frequently damaged. At this time, the patterned edge adjacent to the sealing portion 120 of the battery is in a state with a very small radius of curvature, and the bending durability of the flexible battery 1 can be easily determined by repeatedly folding the outer material 100. The state with the smallest radius of curvature is the folded state, and repeated folding is performed towards the second functional layer 240 side of the bent outer material 100 of the flexible battery 1. In other words, when folded, the folded inner side of the outer material 100 serves as a protective layer for the second functional layer 240, and the outer side serves as a sealing layer for the first functional layer 220. When the outer material 100 is folded such that the second functional layer 240 is located inside, the radius of curvature of the folded barrier layer 230 can be 0.03 mm or more.

[0081] That is, in this application, the thickness of the second functional layer 240 is the thickest in the total thickness of the outer material 100, thereby providing the advantage of being able to prevent damage to the patterned portion 115 of the outer material 100 of the flexible battery 1 and the patterned edge adjacent to the sealing portion 120.

[0082] Figure 2c This diagram illustrates an embodiment of an exterior material comprising a multilayer structure including a sealing layer and a reinforcing resin layer, a first functional layer, a barrier layer, a second functional layer, and an anti-corrosion layer, according to an embodiment of the present invention. (Refer to...) Figure 2c The outer casing material 100 may include a first functional layer 220, an anti-corrosion layer 270, a barrier layer 230, and a second functional layer 240. The outer casing material 100 may also include an adhesive layer 260 located between the layers.

[0083] The anti-corrosion layer 270 serves to prevent the electrolyte in the outer casing material 100 from reacting with the barrier layer 230. The anti-corrosion layer 270 can be configured to have a thickness of about 3 to 6 μm, including the adhesive layer 260.

[0084] The first functional layer 220 is composed of one or more resin layers including a sealing layer 255, and may also include a reinforcing resin layer 250 with a melting point higher than that of the sealing layer 255. For example, the reinforcing resin layer 250 is laminated between the sealing layer 255 and the barrier layer 230 on the sealing layer 255. The reinforcing resin layer 250 is thicker than the anti-corrosion layer 270. For example, the reinforcing resin layer 250 has a thickness of about 10 μm or more, which is the total thickness of the outer material 100. It can be configured to have a thickness of 0.25 times to 4.2 times that of the sealing layer 255. The reinforcing resin layer 250 can perform the following functions: when sealing, it prevents the thickness of the sealing portion 120 from decreasing rapidly and protects the barrier layer 230, which is the first to be damaged due to repeated deformation.

[0085] The reinforcing resin layer 250 is a polymer layer with a melting point higher than that of the sealing layer 255, for example, it may be made of polyamide. Because the reinforcing resin layer 250 is made of a polymer layer with a melting point higher than that of the sealing layer 255, when the outer materials 100 are bonded together by heat, it prevents the sealing layer 255 from melting to a predetermined thickness due to the sealing temperature, and lengthens the electrolyte movement path up to the barrier layer 230. This performs the function of maximally delaying the reaction between the electrolyte and the barrier layer 230, thereby providing both protection and flexibility to the barrier layer 230.

[0086] In the flexible battery 1 including the reinforcing resin layer 250, the thickness of the sealing portion 120 is increased, thereby increasing the radius of curvature when the flexible battery 1 is bent, which improves the bending durability of the flexible battery 1.

[0087] That is, in this application, the first functional layer 220 of the outer material 100 also includes a reinforcing resin layer 250 as a polymer layer, which has the following advantages: not only can the repeated bending durability, which is one of the evaluation indicators of the flexibility of the flexible battery 1, be improved on the outer side of the outer material 100, but the repeated bending durability, which is one of the evaluation indicators of the flexibility of the flexible battery 1, can also be improved on the sealing part 120 of the outer material 100.

[0088] Figure 3a and Figure 3b This is an illustrative diagram illustrating the process of sealing two outer packaging materials according to an embodiment of the present invention.

[0089] Figure 3a A diagram illustrating the process of sealing external materials using existing sealing layers. (Refer to...) Figure 3a In the case of sealing two outer materials 210 in the past, two existing sealing layers 211 with a thickness of about 80 μm are combined to have a thickness of about 160 μm, and the two sealing layers 211 are sealed to a thickness of about 80 μm, which is equivalent to 50% of the combined thickness.

[0090] Figure 3b This diagram illustrates an example of the process of sealing an outer material using a first functional layer comprising a sealing layer and a reinforcing resin layer, according to an embodiment of the present invention. (Refer to...) Figure 3b The first functional layer 220 may include a sealing layer 255 and a reinforcing resin layer 250. The reinforcing resin layer 250 is thicker than the anti-corrosion layer 270, and the reinforcing resin layer 250 may be composed of a thickness of about 10 μm or more.

[0091] For example, when sealing two outer materials 100 including a first functional layer 220 consisting of a sealing layer 255 and a reinforcing resin layer 250, the ratio of the thickness of the reinforcing resin layer 250 to the thickness of the sealing layer 255 (reinforcing resin layer / sealing layer) can be configured to have a range of 0.25 (reinforcing resin layer = 10 μm, sealing layer = 40 μm, barrier layer = 25 μm, second functional layer (protective layer) = 50 μm) to 4.2 (reinforcing resin layer = 105 μm, sealing layer = 25 μm, barrier layer = 25 μm, second functional layer (protective layer) = 80 μm).

[0092] If the thickness ratio between the reinforcing resin layer 250 and the sealing layer 255 is less than 0.25, the barrier layer 230 cannot function to protect itself from damage caused by the robust non-uniform layer when the non-uniform layer generated around the sealed portion 130 of the battery is suppressed and the battery is repeatedly deformed. If the thickness ratio between the reinforcing resin layer 250 and the sealing layer 255 is greater than 4.2, the ratio of the barrier layer 230 to the second functional layer 240 is relatively reduced, thereby reducing formability and durability, increasing the total thickness of the outer casing material 100, and potentially causing a decrease in the energy density of the battery. Therefore, preferably, the thickness ratio between the reinforcing resin layer 250 and the sealing layer 255 can be set to a value between 0.25 and 4.2.

[0093] The first functional layer 220 is composed of one or more resin layers including a sealing layer 255. The thickness of the sealing layer 255 is greater than or equal to the thickness of the barrier layer 230, and can be approximately 25 μm or more. This is because the outer casing material of a conventional battery is formed for the purpose of sealing and moldability. In contrast, in the outer casing material 100 of the flexible battery 1 of this application, the sealing layer 255 is formed primarily for sealing. Therefore, when performing the sealing process of the flexible battery 1, considering the left and right process deviations, the sealing layer 255 can be prepared with a thickness of approximately 25 μm or more to achieve sealing.

[0094] The optimal thickness ratio of the reinforced resin layer 250 to the sealing layer 255 can be approximately 6:4.

[0095] When the reinforced resin layer 250 and the sealing layer 255 are prepared with appropriate thickness ratios, the following advantages can be provided: the sealing layer 255 can perform sealing, and the reinforced resin layer 250 can significantly contribute to the protection and moldability of the barrier layer 230. Thus, during the sealing process of the outer material 100, the formation of an uneven layer around the seal 130 can be suppressed.

[0096] The following is through Figures 4 to 6This describes a method for evaluating the properties of an outer casing material 100 composed of a multi-layered structure. The outer casing material 100 may be composed of a first functional layer 220, a barrier layer 230, and a second functional layer 240. The barrier layer 230 may be located between the first functional layer 220 and the second functional layer 240; for example, the barrier layer 230 may be configured to have a thickness of 25 μm or more.

[0097] According to one embodiment, in order to confirm the processability of each material of the outer casing material 100 constituting the multi-layer structure, pattern forming can be performed by a mold.

[0098] The results confirm that the sealing layer, which is the first functional layer 220, has low pattern formability but excellent elongation. This confirms that when molding the outer casing material 100, the state of the barrier layer 230 due to depth is improved to the maximum extent.

[0099] The results confirm that the pattern forming properties of the barrier layer 230 are excellent.

[0100] The execution results confirm that the pattern forming performance of the second functional layer 240 is generally poor.

[0101] Based on the above evaluation, the barrier layer 230 has the greatest impact on the pattern processing of the outer material 100, i.e., its formability. The barrier layer 230, which is made of aluminum foil, must be at least 25 μm thick to maintain the pattern shape of the outer material 100. However, when the thickness of the barrier layer 230 is less than 25 μm, the proportion of other structural layers is high, which can reduce formability.

[0102] Figure 4 An illustrative diagram illustrating the characteristics of an outer casing material comprising a multilayer structure according to an embodiment of the present invention and a battery utilizing the same. (Refer to...) Figure 4 The outer material 100 may be composed of a first functional layer 220, a barrier layer 230, and a second functional layer 240. For example, the total thickness of the outer material 100 may be configured to have a thickness of 100 μm to 300 μm, and the thickness of the barrier layer 230 may be configured to have a thickness of 25 μm or more.

[0103] A basic assessment is performed on the formability, sealing, flexibility, and bending durability of the outer casing material 100. Formability refers to the degree of formation of the corrugated pattern of the outer casing material 100; sealing refers to the degree of sealing during heat sealing; flexibility refers to the flexibility of the flexible battery 1 using this outer casing material 100; and bending durability refers to the degree of damage to the outer casing material 100 when the flexible battery 1 is subjected to repeated bending assessment.

[0104] Experimental results confirm that the total thickness of the outer casing material 100 is less than 100 μm. Figure 4In cases where the total thickness of the outer material 100 is greater than 400 μm, the pattern forming performance is poor, and during repeated bending evaluations, numerous pin holes, cracks, and other damages occur in the outer material 100. Furthermore, it can be confirmed that when the total thickness of the outer material 100 exceeds 300 μm... Figure 4 In the case of 420), the flexibility of the outer material 100 is significantly reduced, resulting in a bent shape. Consequently, the internal electrodes also bend and break, leading to poor bending durability. Furthermore, it is observed that the energy density of the flexible battery 1 decreases as the total thickness of the outer material 100 increases.

[0105] That is, according to the evaluation results, the total thickness of the optimal outer casing material 100 can range from 100μm to 300μm. Figure 4 It consists of 410.

[0106] Figure 5a and Figure 5b This is an illustrative diagram used to illustrate an embodiment of the present invention, showing the radius of curvature of the barrier layer of the outer casing material based on the thickness of the second functional layer and the folding evaluation of the outer casing material.

[0107] Reference Figure 5a The existing outer material 210 is composed of a sealing layer 211, a barrier layer 212 and a protective layer 213. The multi-layer structure of the existing outer material 210 is configured such that the thickness of the barrier layer 212 + the protective layer 213 < the sealing layer 211.

[0108] However, the outer casing material 100 proposed in this application is composed of a first functional layer 220, a barrier layer 230, and a second functional layer 240. The multilayer structure constituting the outer casing material 100 of this application can be configured to have a thickness where the first functional layer 220 < the barrier layer 230 + the second functional layer 240. For example, the total thickness of the outer casing material 100 proposed in this application can be configured to have a thickness of 100 μm to 300 μm, and the thickness of the barrier layer 230 can be configured to have a thickness of 25 μm or more.

[0109] Reference Figure 5b It can be confirmed that when the outer casing 100 is folded in such a way that the second functional layer 240 is located inside the outer casing 100, the radius of curvature R of the barrier layer 230 in the outer casing 100 proposed in this application is... Figure 5b The radius of curvature R of the barrier layer 212 in the existing outer material 210 is greater than 500. Figure 5b (510). Wherein, when the outer material 100 is folded such that the second functional layer 240 is located internally, the radius of curvature of the folded barrier layer 230 can be 0.03 mm or more. (Refer to...) Figure 5bIt is known that when the outer material 100 is folded, the radius of curvature of the barrier layers 230 and 212 is the same as the thickness of the second functional layer 240 and the existing protective layer 213 of this application. This is because when the minimum total thickness of the outer material 100 is 100 μm, the second functional layer 240 is more than 33% of the total thickness of the outer material 100.

[0110] The outer casing material 100 can be folded for evaluation. For example, after punching the outer casing material 100 in a dumbbell shape (e.g., width: 10 mm, length: 100 mm), and pressing the center portion of the sample with a specified pressure (e.g., gauge pressure: 0.2 MPa) for a specified time (e.g., 2 seconds), if the radius of curvature R is minimal when bending the outer casing material 100, it can be in a folded state. At this time, by repeatedly folding and unfolding the flexible battery 1 with the side of the second functional layer 240 that is bent as the folding direction, it can be confirmed whether the barrier layer 230 of the outer casing material 100 is damaged.

[0111] Typically, in the flexible battery 1, damage to the outer material 100 occurs at the edge of the pattern adjacent to the patterned portion 115, where the sealing portion 120 has the smallest radius of curvature R. The outer material 100 is in a folded state, and the bending assessment of the flexible battery 1 can be performed in the outward direction from the second functional layer 240 side.

[0112] To improve this problem, this application allows the second functional layer 240 to have a thickness of more than 33% of the total thickness of the outer material 100, thereby increasing the radius of curvature of the barrier layer 230 in the bent outer material 100 to improve bending durability.

[0113] Figure 6 This diagram illustrates an example of comparing and evaluating the durability of an outer casing material based on the thickness of the second functional layer through a folding evaluation of an outer casing material comprising a multi-layered structure according to an embodiment of the present invention. (Refer to...) Figure 6 By evaluating the folding of the outer material 100, the durability effect of the outer material 100 through the thickness of the second functional layer 240 can be confirmed.

[0114] The following explanation compares a comparative example and an embodiment to illustrate the case where the outer material 100 is folded 10 times. The comparative example represents a case where the barrier layer 230 is damaged, while the embodiment represents a case where the barrier layer 230 is not damaged.

[0115] This confirms that, in the case of currently commercially available casing materials, the protective layer accounts for a low proportion of the total thickness of the casing material. However, in the case of commercially available casing materials, it was confirmed that the barrier layer broke after 10 repeated folds. Therefore, in this folding evaluation, 10 folds were set as the evaluation standard. Furthermore, the evaluation confirmed that the casing material constructed in a manner that delays and mitigates damage to the barrier layer in more than 10 folds, and the flexible battery including this casing material, exhibit excellent flexural durability.

[0116] According to Comparative Example 3, with the total thickness of the outer material being "113 μm", the thickness of the second functional layer being "25 μm", the thickness of the barrier layer being "40 μm", and the thickness of the sealing layer including the first functional layer being "45 μm", the barrier layer was found to break after 10 folds. In the case of Comparative Example 3, the thickness of the second functional layer was configured to be thinner than the thickness of the barrier layer, and the thickness of the second functional layer was configured to be approximately 22% of the total thickness of the outer material. Therefore, it was confirmed that the barrier layer broke after only 10 folds.

[0117] According to Comparative Example 4, with the total thickness of the outer material being "150 μm", the thickness of the second functional layer being "25 μm", the thickness of the barrier layer being "40 μm", and the thickness of the first functional layer being "80 μm", the barrier layer was found to break after 10 folds. In Comparative Example 4, the thickness of the second functional layer was configured to be thinner than that of the barrier layer, and the thickness of the second functional layer was configured to be approximately 16% of the total thickness of the outer material. Therefore, it was confirmed that the barrier layer broke after only 10 folds.

[0118] According to Comparative Example 5, with the total thickness of the outer material being "146 μm", the thickness of the second functional layer being "45 μm", the thickness of the barrier layer being "35 μm", and the thickness of the first functional layer being "60 μm", after 10 folds, it was confirmed that a portion of the barrier layer was damaged. In Comparative Example 5, the thickness of the second functional layer was configured to be thicker than the thickness of the barrier layer, and the thickness of the second functional layer was configured to be approximately 30% of the total thickness of the outer material. Therefore, it was confirmed that a portion of the barrier layer was damaged after 10 folds. Unlike Comparative Examples 3 and 4, where the thickness of the second functional layer was thinner than the thickness of the barrier layer, in Comparative Example 5, the thickness of the second functional layer was thicker than the thickness of the barrier layer. After 10 folds, a portion of the barrier layer was damaged, rather than the entire barrier layer, thus confirming that the bending durability of the outer material including the barrier layer was improved.

[0119] According to Example 5, with the total thickness of the outer material being "120 μm", the thickness of the second functional layer being "40 μm", the thickness of the barrier layer being "35 μm", and the thickness of the first functional layer being "40 μm", after 20 folds, it was confirmed that a portion of the barrier layer was damaged. In Example 5, it was confirmed that the thickness of the second functional layer was greater than the thickness of the barrier layer, and the thickness of the second functional layer was configured to be approximately 33% of the total thickness of the outer material. Unlike Comparative Examples 3 to 5, where part or all of the barrier layer was damaged after 10 folds, in Example 5, the thickness of the second functional layer was configured to be approximately 33% of the total thickness of the outer material, and a portion of the barrier layer was damaged after more than 20 folds (more than 10 folds). Therefore, it was confirmed that the durability of the outer material was improved.

[0120] According to Example 6, with the total thickness of the outer material being "153 μm", the thickness of the second functional layer being "55 μm", the thickness of the barrier layer being "40 μm", and the thickness of the first functional layer being "50 μm", after 30 folds, it was confirmed that a portion of the barrier layer was damaged. In the case of Example 6, it was confirmed that the thickness of the second functional layer is greater than the thickness of the barrier layer, and the thickness of the second functional layer is configured to be approximately 35% of the total thickness of the outer material.

[0121] According to Example 7, with the total thickness of the outer material being "155 μm", the thickness of the second functional layer being "65 μm", the thickness of the barrier layer being "35 μm", and the thickness of the first functional layer being "50 μm", the barrier layer remained undamaged after 30 folds. In Example 7 where the barrier layer was undamaged, it was confirmed that the thickness of the second functional layer was greater than the thickness of the barrier layer, and the thickness of the second functional layer was configured to be approximately 41% of the total thickness of the outer material.

[0122] According to Example 8, with the total thickness of the outer material being "250 μm", the thickness of the second functional layer being "120 μm", and the thickness of the barrier layer being "40 μm", and the thickness of the first functional layer being "80 μm", the barrier layer was not damaged after 30 folds. In Example 8, where the barrier layer was not damaged, it was confirmed that the thickness of the second functional layer was greater than the thickness of the barrier layer, and the thickness of the second functional layer was configured to be 48% of the total thickness of the outer material. Experimental results, through comparison of Comparative Examples 3 to 5 and Examples 5 to 8, confirmed that when the thickness of the second functional layer was greater than the thickness of the barrier layer, damage to the barrier layer was reduced. Furthermore, through Examples 5 to 8, it was confirmed that the thickness of the second functional layer accounted for approximately 33% or more of the total thickness of the outer material, and the higher the proportion of the second functional layer thickness in the total thickness of the outer material, the less damage to the barrier layer was caused by the number of folds.

[0123] That is, the thickness of the second functional layer is less than 33% of the total thickness of the outer material 100. Figure 6 In the case of 600), the pattern forming or sealing performance was excellent, but after 10 to 20 folds ( Figure 6 The result is that the barrier layer (630) is broken. However, the thickness of the second functional layer 240 is more than 33% of the total thickness of the outer material 100. Figure 6 In the case of (610), it can be confirmed that the barrier layer 230 is improved to not break after 20 folds. The higher the proportion of the thickness of the second functional layer 240, which consists of multiple layers, relative to the total thickness of the outer material 100, the less damage occurs to the outer material 100. Battery bending durability evaluation also confirms that when the thickness of the second functional layer 240 is configured to be more than 33% of the total thickness of the outer material 100, repeated bending evaluations performed on the battery 1 in a bending environment of R: 20, 25 rpm confirm that no damage to the outer material 100 or electrolyte leakage occurred in more than 3000 cycles.

[0124] Figure 7 This is a flowchart of a method for preparing a battery using an external material according to an embodiment of the present invention.

[0125] In step S710, at least one patterned portion 115 is formed on the outer casing material 100. For example, at least one patterned portion 115 may be formed on the surfaces of the upper and lower surfaces of the outer casing material 100, which is composed of a first functional layer 220 including a sealing layer, a barrier layer 230, and a second functional layer 240. Alternatively, at least one patterned portion 115 may be formed on the surfaces of the upper and lower surfaces of the outer casing material 100, which is composed of a first functional layer 220 including a sealing layer and a reinforcing resin layer 250, a barrier layer 230, and a second functional layer 240. The outer casing material 100 may also include an anti-corrosion layer 270.

[0126] In step S720, the outer material 100 on which the patterned portion 115 is formed can be folded. At this time, when the outer material 100 is folded, the first side portion of the outer material 100 can be sealed.

[0127] In step S730, electrode assemblies 200 can be inserted between the folded outer materials 100.

[0128] In step S740, the electrode assembly 200 in the outer casing material 100 can be sealed by the sealing part 120. At this time, after sealing the upper and lower parts of the outer casing material 100 and injecting electrolyte into the interior of the outer casing material 100, the second side part can be finally sealed by the formation process and the degassing process.

[0129] Step S740 may include the following steps: performing a heat-melting process on the sealing portion 120; thermally deforming the sealing layer of the outer material 100 included in the sealing portion 120; and generating a non-uniform layer in the sealing periphery 130 located around the sealing portion 120. In the step of performing the heat-melting process, the sealing portion 120 is sealed after heat-melting is performed on the sealing portion 120 along the four directions of the outer material 100. The heat-melting process may be performed at a temperature of 170°C to 190°C for a specified time (e.g., 3 seconds).

[0130] Although not in Figure 7 As shown, the first functional layer 220 of the outer casing material 100 further includes a reinforcing resin layer 250, which is formed between the anti-corrosion layer 270 and the sealing layer. The reinforcing resin layer 250 is thicker than the anti-corrosion layer 270 and may have a thickness of 10 μm or more. The reinforcing resin layer 250 may be composed of a polymer with a melting point higher than that of the sealing layer. For example, the reinforcing resin layer 250 is a heat-resistant resin layer with a melting point of 200°C or higher, which can suppress the formation of previously generated uneven layers when the battery 1 is sealed. The uneven layer refers to the following: when the electrode assembly 200 is disposed inside the outer casing material 100 and the outer casing material 100 is heat-melted, the material of the sealing layer of the outer casing material 100 (e.g., CPP) is partially extruded from the interface portion of the sealing portion 120 due to thermal deformation and protrudes into the sealing periphery portion 130 located between the pattern portion 115 and the sealing portion 120.

[0131] By disposing the reinforcing resin layer 250 between the anti-corrosion layer 270 and the sealing layer, an uneven layer of the sealing layer is generated without any change in the thickness of the reinforcing resin layer 250, and the generation of the uneven layer is minimized. Furthermore, when the battery is repeatedly deformed, the reinforcing resin layer 250 can protect the barrier layer 230 from damage caused by the firmly fixed uneven layer.

[0132] For example, refer to Figure 1b If we assume that the thickness of the sealing part 120 is "T1", then the thickness of the sealing surrounding part 130 can be configured as "T2", which is within 300% of "T1", according to the functional layer.

[0133] When the thickness "T2" of the sealing perimeter 130 exceeds 300% of the thickness "T1" of the sealing portion 120, the difference in thickness between "T1" and "T2" increases when the flexible battery 1 is repeatedly deformed. This causes damage to the pattern edge portion of the outer material 100 of the sealing perimeter 130, which corresponds to the sealing portion 120 and the pattern portion 115. Therefore, it is necessary to control the non-uniform layer so that the thickness "T2" of the sealing perimeter 130 is within 300% of the thickness "T1" of the sealing portion 120. That is, whether the edge portion of the outer material 100 is damaged can be determined based on whether the reinforcing resin layer 250 is included.

[0134] For example, the existing outer casing material 210 has a total thickness of 113 μm, and the sealing layer 211 is composed of 40 μm cast polypropylene (CPP, CPP). The sealing portion of the outer casing material 210 is heat-fused at a sealing temperature of 170°C to 190°C. The existing outer casing material 210 does not include the reinforcing resin layer 250. For five samples, heat fusion was performed with a sealing time of 3 seconds and a sealing pressure of 1 MPa.

[0135] The thickness of the sealing portion 120 was determined by micrometer measurement. At temperatures between 170°C and 180°C, the thickness T1 of the sealing portion 120 of the outer material 210 heat-melted was 204 μm ± 2%, with little change in thickness before and after sealing. However, at temperatures above 185°C, the thickness T1 of the sealing portion 120 of the outer material 210 heat-melted was 167 μm ± 1%, representing a reduction of approximately 75% in the thickness of the upper and lower CPP layers in the area of ​​the sealing portion 120. Furthermore, the thickness T2 in the sealing perimeter portion 130 adjacent to the sealing portion 120 significantly increased to 633 μm ± 10%. This is caused by an uneven layer, where the casting was done at a temperature much higher than the melting point of the cast polypropylene used as the sealing layer 211, resulting in severe thermal deformation of the cast polypropylene, which was then extruded towards the side of the sealing portion 120 (the sealing perimeter portion 130 located between the pattern portion 115 and the sealing portion 120). Due to the uneven layer, the thickness difference in the boundary of the sealing portion 120 is large. When the flexible battery 1 is continuously bent and deformed, physical pressure accumulates in the barrier layer 212 of the outer material 210. As a result, the following problem occurs: the edge portion of the outer material 210 corresponding to the sealing perimeter portion 130 adjacent to the sealing portion 120 and the pattern portion 115 is damaged (for example, when the bending evaluation is performed at R20, 25 rpm, it is damaged after less than 3000 bends) and acts as a movement path for moisture to penetrate from the outside.

[0136] To improve this problem, in this application, a first functional layer 220 is added between the anti-corrosion layer 270 and the sealing layer, and is a polymer (e.g., polyamide) of one of the heat-resistant resin layers with a melting point above 200°C as a reinforcing resin layer 250.

[0137] For example, the outer casing material 100 has a total thickness of 120 μm, the sealing layer is a 30 μm cast polypropylene, and the reinforcing resin layer 250 is composed of 15 μm polyamide. The upper and lower surfaces of the outer casing material 100 are heat-fused at a sealing temperature of 170℃ to 190℃. For five samples, the heat-fusion process was performed with a sealing time of 3 seconds and a sealing pressure of 3 MPa.

[0138] The thickness of the sealing portion 120 was determined by micrometer measurements. At temperatures between 170°C and 180°C, the thickness T1 of the sealing portion 120 of the heat-melted outer material 100 was 211 μm ± 2%, and at temperatures above 185°C, the thickness T1 was 196 μm ± 2%. The rapid decrease in the thickness of the sealing portion 120 was mitigated by reducing the thickness of the cast polypropylene in the region corresponding to the sealing layer and by adding the reinforcing resin layer 250. Furthermore, the thickness T2 in the sealing perimeter portion 130 adjacent to the sealing portion 120 was also 413 μm ± 10%, thus mitigating the increase in thickness. This is because by adding the reinforcing resin layer 250 and reducing the proportion of the sealing layer, the amount of uneven layer extruded to the side of the sealing portion 120 was reduced, thereby reducing the thickness.

[0139] Based on the results of repeated bending evaluation of the flexible battery 1, the following experimental results can be derived: For the damage to the barrier layer 230 of the outer material 100 caused by the non-uniform layer, the reinforcing resin layer 250 protects the barrier layer 230, and the bending durability (for example, when the bending evaluation is performed at R20, 25 rpm, the pattern edge of the sealing periphery 130 of the outer material 100 will not be damaged even after 5000 bends) is significantly improved.

[0140] As a result of the formation of the non-uniform layer, a thickness difference can be generated between the sealing portion 120 and the sealing periphery portion 130 where the non-uniform layer is formed. The sealing periphery portion 130 where the non-uniform layer is formed can be configured to have a thickness of up to 300% of the thickness of the sealing portion 120 according to the reinforced resin layer 250.

[0141] In the above description, steps S710 to S740 can be further divided into additional steps or combined into fewer steps according to the implementation of the present invention. Furthermore, some steps can be omitted as needed, and the order of the steps can be changed.

[0142] The foregoing description of the present invention is illustrative, and it will be understood by those skilled in the art that it can be easily modified into other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above are merely illustrative in all respects and should not be construed as limiting. For example, components described as a single element can also be implemented separately; similarly, components described separately can also be implemented in combination.

[0143] The scope of this invention is set forth in the claims rather than in the detailed description, and the meaning and scope of the claims, as well as all variations or modifications derived therefrom, are included within the scope of this invention.

Claims

1. A battery, utilizing an external material, characterized in that, include: The outer casing material includes a barrier layer, a first functional layer, a second functional layer, and an anti-corrosion layer, wherein the first functional layer is formed on one surface of the barrier layer, the second functional layer is formed on the other surface of the barrier layer, and the anti-corrosion layer is formed on at least one surface of the barrier layer. Electrode assemblies, which are inserted between the outer casing materials; and A sealing portion for sealing the electrode assembly within the outer casing material. The first functional layer is composed of one or more resin layers, including a sealing layer. The second functional layer is thicker than the barrier layer and has a thickness of more than 33% of the total thickness of the outer casing material. The outer casing material includes a receiving section that forms a space for receiving the electrode assembly. The receiving portion of the outer material includes a patterned portion having alternating protrusions and depressions along the thickness direction. The first functional layer further includes a reinforcing resin layer, the reinforcing resin layer having a higher melting point than the sealing layer. The battery further includes a non-uniform layer, which is formed in the sealing periphery located between the patterned portion and the sealing portion by thermally deforming the sealing layer included in the sealing portion through a hot-melt process. The thickness of the sealing periphery is greater than the thickness of the sealing portion, and the thickness of the sealing periphery is within 300% of the thickness of the sealing portion. The reinforced resin layer is formed between the anti-corrosion layer and the sealing layer.

2. The battery according to claim 1, characterized in that, The formation of the non-uniform layer creates a thickness difference between the sealing portion and the sealing periphery where the non-uniform layer is formed.

3. The battery according to claim 1, characterized in that, The reinforced resin layer is thicker than the anti-corrosion layer, and has a thickness of more than 10 μm.

4. The battery according to claim 1, characterized in that, The hot-melt process is performed at a temperature of 120°C to 190°C.

5. The battery according to claim 1, characterized in that, The melting point of the reinforced resin layer is above 200°C.

6. The battery according to claim 1, characterized in that, The reinforcing resin layer has a thickness of 0.25 to 4.2 times that of the sealing layer.

7. The battery according to claim 1, characterized in that, The barrier layer has a thickness of 25 μm or more. The total thickness of the outer casing material is 100 μm to 300 μm.

8. The battery according to claim 1, characterized in that, When the outer material is folded in such a way that the second functional layer is located inside, the radius of curvature of the folded barrier layer is 0.03 mm or more.

9. The battery according to claim 1, characterized in that, The sealing layer is thicker than or equal to the thickness of the barrier layer, having a thickness of 25 μm or more.

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