Enclosure material, method of forming a pattern on the enclosure material, and method of producing a battery including the enclosure material

Abstract

The exterior material used in the battery includes at least one pattern portion formed in the MD (Machine Direction) of the exterior material, the MD of the exterior material being the width direction of the battery including the exterior material, and the TD (Transverse Direction) of the exterior material being the length direction of the battery including the exterior material.

Description

[Technical field]

[0001] The present invention relates to a packaging material, a method for patterning the packaging material, and a method for producing a battery including the packaging material. [Background technology]

[0002] An electrochemical cell refers to an assembly that is composed of at least two electrodes and an electrolyte and is capable of providing electrical energy. In particular, lithium-ion batteries, which are composed of secondary cells that can be charged and discharged, are widely used in various cutting-edge electronic devices including smartphones.

[0003] Recently, various attempts have been made to break away from conventional designs in the design of mobile devices including smartphones and various wearable devices, and flexible devices that can be bent while maintaining their functionality have been attracting attention. Therefore, it is important to ensure the functionality and safety of flexible electrochemical cells that can be built into such flexible devices and used as a power source.

[0004] When a flexible battery is repeatedly bent and unfolded, the exterior material may be damaged. If the exterior material is severely damaged, the electrolyte inside may leak. Even if the exterior material is only slightly damaged, moisture in the air may penetrate into the battery, causing swelling of the battery, damaging the electrodes and reducing the capacity and output of the battery.

[0005] Therefore, in order to prevent the exterior material of the flexible battery from being damaged by absorbing the compressive and tensile stresses that occur in the area where the battery is bent, pattern processing is performed on the exterior material using an upper and lower die press. Since a battery using a patterned exterior material has a higher elastic modulus than a battery using an unpatterned exterior material, the force acting on the exterior material when the battery is bent is dispersed rather than being concentrated on one side. This prevents the exterior material and the electrode assembly housed inside from being severely broken in any part.

[0006] On the other hand, the pattern of the exterior material does not need to be deeply molded, but it is necessary to minimize damage to the exterior material caused by repeated bending, warping, folding, twisting, etc. of the battery, and improve the durability of the battery.

[0007] When an external force acts on a battery, for example when the battery is bent, folded, or twisted, the compressive force applied in the thickness direction of the exterior material has a greater impact on the durability of the battery than the tensile force in the length direction.

[0008] In addition, as the electrode assembly housed inside the exterior material deforms, a force is applied that pushes the exterior material outward. If the exterior material cannot withstand the force applied from the internal electrode assembly, the internal electrode assembly is likely to break around a weak portion of the exterior material, and the exterior material in that portion is damaged, which may cause a decrease in battery performance and safety issues such as swelling and leakage.

[0009] To further improve the durability of flexible batteries, a pattern processing method is required that can increase the bending moment in the area where the battery is bent. Specifically, to increase the bending durability of flexible batteries, a method is required for forming a pattern that increases the fatigue life of the exterior material. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 2005-0052069 (published on June 2, 2005) [Patent Document 2] Japanese Patent Publication No. 2013-218991 (Published on October 24, 2013) Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention is intended to solve the problems of the conventional technology described above, and aims to provide an exterior material for use in a battery, which includes at least one pattern portion formed in the MD (Machine Direction) of the exterior material, the MD of the exterior material being the width direction of a battery including the exterior material, and the TD (Transverse Direction) of the exterior material being the length direction of a battery including the exterior material.

[0012] One object of the present invention is to provide a method for forming a pattern in an exterior material in a direction that increases the fatigue life of the exterior material so as to prevent damage to the exterior material and improve the durability of the battery, and a method for producing a battery including the exterior material.

[0013] However, the technical problems to be solved by this embodiment are not limited to those described above, and other technical problems may exist. [Means for solving the problem]

[0014] As a means for achieving the above-mentioned technical objective, one embodiment of the present invention provides an exterior material for use in a battery, the exterior material including at least one pattern portion formed in the MD (Machine Direction) of the exterior material, the MD of the exterior material being the width direction of the battery including the exterior material, and the TD (Transverse Direction) of the exterior material being the length direction of the battery including the exterior material.

[0015] In one embodiment, the outer casing is folded into the TD of the outer casing and used during the manufacture of the battery, and the outer casing used during the manufacture of the battery may be bent into the TD of the outer casing, such that the battery is bent into the TD of the outer casing.

[0016] In one embodiment, the outer casing may be folded into the MD of the outer casing and used during the manufacture of the battery, and the outer casing used during the manufacture of the battery may be bent into the TD of the outer casing, thereby bending the battery into the TD of the outer casing.

[0017] In one embodiment, the outer casing further includes a sealing portion that surrounds the pattern portion and joins portions of the two surfaces to form an enclosed space between the two surfaces, and an edge portion of the pattern portion may be adjacent to the sealing portion.

[0018] In one embodiment, a radius of curvature for an edge portion of the pattern portion may be smaller than a radius of curvature for a center portion of the pattern portion.

[0019] In one embodiment, the radius of curvature may become smaller from the center of the pattern portion toward the edge portion of the pattern portion.

[0020] In one embodiment, the pattern portion may be formed in the MD of the exterior material, taking into consideration the possibility of damage to an edge portion of the pattern portion.

[0021] In one embodiment, the fatigue life against deformation of an edge portion of the pattern portion may be set based on the pattern portion formed in the MD of the exterior material.

[0022] In one embodiment, the fatigue life against deformation of the edge portion of the pattern portion may be longer than the fatigue life against deformation of the edge portion of a pattern portion of another exterior material that includes at least one pattern portion formed in the TD of the exterior material.

[0023] In one embodiment, the exterior material may be formed in a multi-layer structure in which at least one material is laminated.

[0024] Another embodiment of the present invention is a method for forming a pattern on an exterior material, the method comprising the steps of positioning the exterior material between an upper mold and a lower mold, and forming at least one pattern portion in the MD (Machine Direction) of the exterior material by stamping the exterior material using the upper mold and the lower mold, wherein the MD of the exterior material may be a width direction of a battery including the exterior material, and the TD (Transverse Direction) of the exterior material may be a length direction of a battery including the exterior material.

[0025] Another embodiment of the present invention is a method for producing a battery including an outer casing, the method including the steps of forming at least one pattern portion on the outer casing in a machine direction (MD) of the outer casing, folding the outer casing, inserting an electrode assembly into the folded outer casing, and sealing the outer casing with the electrode assembly inserted, wherein the MD of the outer casing may be a width direction of a battery including the outer casing, and the TD (transverse direction) of the outer casing may be a length direction of a battery including the outer casing. Effect of the Invention

[0026] According to any one of the means for solving the problems of the present invention described above, the present invention can provide an exterior material for use in a battery, which includes at least one pattern portion formed in the MD (Machine Direction) of the exterior material, the MD of the exterior material being the width direction of a battery including the exterior material, and the TD (Transverse Direction) of the exterior material being the length direction of a battery including the exterior material.

[0027] In addition, a method for forming a pattern on an exterior material in a direction in which the fatigue life of the exterior material is long and a method for producing a battery including the exterior material can be provided, which can reduce damage to pattern edge portions having a small radius of curvature and improve the bending durability of the battery.

[0028] In addition, damage to the pattern edges of the exterior material and leakage of electrolyte can be prevented, thereby improving the safety of the battery during use. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a diagram illustrating an example of an exterior material. [Diagram 2] 1A and 1B are diagrams illustrating an exterior material and a pattern portion according to an embodiment of the present invention. [Diagram 3] 3 is a diagram showing an exterior material in which a pattern portion is formed in a direction different from that of the pattern portion shown in FIG. 2. [Figure 4a] 1 is a perspective view showing a battery including an exterior material according to an embodiment of the present invention; [Figure 4b] FIG. 4b is a diagram showing the cross-sectional shape of the battery shown in FIG. 4a. [Figure 5a] 4A to 4C are diagrams for explaining the cross-sectional shape of a pattern portion and the radius of curvature of the pattern portion according to one embodiment of the present invention. [Figure 5b] 5A and 5B are diagrams for explaining the radius of curvature of a pattern portion according to an embodiment of the present invention. [Figure 5c] 5A and 5B are diagrams for explaining the shape of a pattern portion in an embodiment of the present invention when viewed from above. [Figure 6] 1 shows a graph of stress-strain ratio. [Figure 7a] 1A and 1B are diagrams for explaining a method for evaluating the bending durability of a battery including an exterior material. [Figure 7b] 10 is a diagram for explaining the force acting on the outer casing material when evaluating the bending durability of a battery including the outer casing material. FIG. [Figure 8] 2 is a flow chart of a method for forming a pattern on a cladding material according to one embodiment of the present invention. [Figure 9] 1 is a flow chart of a method of producing a battery including an enclosure according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, in order to clearly explain the present invention, parts that are not related to the description are omitted, and similar parts are designated by similar reference numerals throughout the specification.

[0031] Throughout the specification, when a part "includes" a certain component, this does not mean excluding other components, but may further include other components, unless otherwise specified. Furthermore, throughout the specification, when a part is "connected" to another part, this includes not only direct connection, but also connection via another member in between, and electrical connection with another element in between. Furthermore, throughout the specification of this application, when a member is located "on" another member, this includes not only contact with the other member, but also the presence of another member between the two members.

[0032] The battery including the exterior material according to the present invention may be, for example, an electrochemical cell, and may be a lithium ion battery. Specifically, the battery including the exterior material according to the present invention may be configured such that an electrode assembly is accommodated together with an electrolyte inside the exterior material and sealed, and is charged and discharged by the movement of lithium ions. The battery including the exterior material according to the present invention may be a flexible battery configured to be bent flexibly while maintaining a state in which it can perform its functions. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0033] 1 is a diagram showing an example of an exterior material. The exterior material 100 may be formed, for example, in a multi-layer structure in which at least one or more materials are laminated. Each of the at least one or more materials may be flexible.

[0034] For example, the multi-layer structure of the exterior material 100 may include a sealing layer, a barrier layer, and a protection layer, which are differentiated according to the function of each layer. The sealing layer may be made of a polypropylene (PP) film. The barrier layer may be made of aluminum foil. The protection layer may be made of a nylon film or a composite layer of nylon and polyethylene terephthalate (PET).

[0035] The exterior material 100 is manufactured by a roll-to-roll process, and the mechanical properties of the exterior material 100 may vary depending on the axial or longitudinal direction of the roll. Here, MD (Machine Direction) may refer to the longitudinal direction of the roll, and TD (Transverse Direction) may refer to the axial direction of the roll.

[0036] In the exterior material used in the flexible battery, the mechanical properties of the battery may vary depending on the direction in which the pattern is formed. That is, a battery including an exterior material in which the pattern is formed in the MD of the exterior material and a battery including an exterior material in which the pattern is formed in the TD of the exterior material may have different mechanical properties. As a result, the direction in which the pattern is formed can affect the durability of the edge portion of the pattern of the flexible battery.

[0037] 2 is a diagram showing an outer casing and a pattern portion according to an embodiment of the present invention. Referring to FIG. 2, the outer casing 100 may include at least one pattern portion 111md formed in the MD of the outer casing 100.

[0038] When a battery is produced to include an outer casing 100 having the pattern portion 111md shown in FIG. 2 formed thereon, the MD of the outer casing may be the width direction 10A of the battery, and the TD of the outer casing may be the length direction 10B of the battery.

[0039] Fig. 3 shows an exterior material on which a pattern portion 111td is formed in a direction different from that of the pattern portion 111md shown in Fig. 2. In the exterior material shown in Fig. 3, the pattern portion 111td is formed in the TD (Transverse Direction) of the exterior material.

[0040] When a battery is produced to include an exterior material on which the pattern portion 111td shown in FIG. 3 is formed, the TD of the exterior material may be the width direction 10A of the battery, and the MD of the exterior material may be the length direction 10B of the battery.

[0041] FIG. 4a is a perspective view showing a battery including an outer casing 100 according to one embodiment of the present invention, and FIG. 4b is a diagram showing the cross-sectional shape of the battery shown in FIG. 4a.

[0042] 4a and 4b, the battery 10 may include a housing 100, an electrode assembly 200 housed inside the housing 100, and an electrode lead 300 connected to the electrode assembly 200.

[0043] The electrode assembly 200 may include a plurality of electrodes and a separator, and may be formed in a structure in which these are stacked in the thickness direction.

[0044] The electrode assembly 200 may include first and second electrodes of different polarities, and a mixture containing an active material may be applied to both sides or cross sections of each of the first and second electrodes. A separator may be sandwiched between the first and second electrodes. For example, the first electrode is a negative electrode, and the current collector used may be made of copper, aluminum, etc., and may be made of a negative electrode active material that is any one or more combinations of graphite, carbon, lithium, silicon, silicon derivatives such as SiOx, silicon-graphite composites, tin, and silicon-tin composites. Also, the second electrode is a positive electrode, and the current collector used may be made of aluminum, stainless steel, etc., and may be made of a positive electrode active material that is any one or more combinations of 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.

[0045] The electrode assembly 200 may have a shape that extends longer in the length direction than in the width direction, of the two directions in which the first and second electrodes extend to form a surface, and has a thin shape in a thickness direction in which the active material and separation membrane are stacked, which intersects (e.g., perpendicular to) the direction in which the surface is formed.

[0046] The electrode assembly 200 may also include an electrode connection tab and a lead connection tab. The electrode connection tabs may be formed to protrude from one end of the first and second electrodes in the longitudinal direction, and electrode connection tabs protruding from electrodes of the same polarity may be connected to each other. The electrodes may be electrically connected in parallel by the electrode connection tabs. The lead connection tabs may be connected to the electrode lead 300 and may protrude from the positive and negative electrodes and be connected to the electrode lead 300.

[0047] Specifically, the exterior material 100 may include a receiving portion 110 and a sealing portion 120. The receiving portion 110 may form a space for receiving the electrode assembly 200, and the sealing portion 120 may be joined to seal the received electrode assembly 200 from the outside. As shown in FIG. 4b, the receiving portion 110 may correspond to a region where two exterior materials 100 face each other at a distance from each other. In order to form the receiving portion 110, the exterior material 100 may be processed to be pressed in the thickness direction and protrude so that a predetermined region of the exterior material 100 has a substantially rectangular vessel (or cup) shape.

[0048] More specifically, at least one pattern portion 111md may be formed on the surface of the storage portion 110 of this embodiment, extending in the MD of the exterior material 100. The pattern portion 111md is a pattern that extends in one direction and is repeatedly arranged in a direction intersecting the one direction, and specifically, may be alternately protruded or recessed in the thickness direction (i.e., alternately protruded in opposite directions) and have an uneven shape along the one direction. Here, the one direction may be the width direction 10A of the battery, which is the MD of the exterior material 100, and the direction in which the pattern portion 111md is repeated may be the length direction 10B of the battery, which is the TD of the exterior material 100. Due to the protruding and recessed pattern portion 111md, the exterior material 100 forming the storage portion 110 may form a wave or wrinkle pattern in the length direction, as shown in FIG. 4b.

[0049] The sealing part 120 may be formed by joining two sealing surfaces. The sealing surface means a joining surface of the exterior material 100, and the two sealing surfaces overlapped along the edge of the accommodating part 110 are joined to each other, so that the internal space (accommodating part 110) can be isolated from the outside. The above-mentioned electrode assembly 200 and electrolyte may be accommodated in the internal space, and the electrode assembly 200 and the electrolyte may be maintained in a sealed state.

[0050] That is, the seal portion 120 may surround the pattern portion 111md and form a sealed space between the two surfaces of the exterior material 100.

[0051] The sealing portion 120 may be a flat plate extending in the width direction 10A or the length direction 10B of the battery. For example, the flat plate of the sealing portion 120 may have a shape in which the surfaces are not bent and face each other. Alternatively, the sealing portion 120 may have a pattern different from the pattern portion 111md, and may have a pattern that is lower in the thickness direction than the pattern portion 111md.

[0052] The edge portion (110e) of the pattern portion may be a portion adjacent to the seal portion 120. For example, the edge portion (110e) of the pattern portion may include an area adjacent to a portion of the seal portion 120 extending in the longitudinal direction 10B of the battery.

[0053] Meanwhile, the electrode lead 300 is connected to the electrode assembly 200 inside the exterior material 100 and extends so as to be exposed to the outside of the exterior material 100. The electrode lead 300 functions as a terminal for electrical connection with the electrode assembly 200 housed inside the exterior material 100, and may be joined so as to penetrate the seal portion 120 in a state where it is sandwiched between the seal surfaces when the seal portion 120 is formed. A pair of electrode leads 300 of positive and negative electrodes may be connected to lead connection tabs provided on the electrode assembly 200 with the same poles.

[0054] The external packaging material 100 of the present invention may be folded in the TD or MD of the external packaging material 100 and used when manufacturing the battery 10. In this case, the external packaging material 100 used when manufacturing the battery 10 is bent in the TD of the external packaging material 100, so that the battery is bent in the TD of the external packaging material 100. That is, the external packaging material 100 can have mobility in the TD of the external packaging material 100 due to a pattern portion having a wave or wrinkle pattern in the MD of the external packaging material 100, so that a battery using the external packaging material 100 can also have mobility in the TD of the external packaging material 100.

[0055] Hereinafter, an exterior material 100 and a pattern portion 111md according to an embodiment of the present invention will be described. Fig. 5a is a diagram showing the cross-sectional shape and curvature radius of the pattern portion 111md according to an embodiment of the present invention. Referring to Fig. 5a, the pattern portion 111md may be formed so that a concave-convex shape having a certain pattern height (h1) and pattern pitch (P) is repeated. When the shape is a wave pattern as in Fig. 5a, the curvature is a degree indicating the bending degree of a curve or a curved surface, and the curvature radius (R) means the radius of a circular arc.

[0056] 5b is a diagram illustrating the radius of curvature of the pattern portion 111md according to an embodiment of the present invention, the radius of curvature of the pattern portion 111md may become smaller from the center of the pattern portion toward the edge of the pattern portion.

[0057] 5c shows the shape of the pattern portion according to one embodiment of the present invention when viewed from above. When the pattern portion 111md is viewed from above, the pattern width to TD may become smaller from the center of the pattern portion toward the edge portion (110e) of the pattern portion. Referring to FIG. 5b and FIG. 5c, the radius of curvature (R2) of the edge portion (110e) of the pattern portion may be smaller than the radius of curvature (R1) of the center portion of the pattern portion.

[0058] When a flexible battery is repeatedly deformed, the probability of damage such as pinholes and cracks occurring is higher at the edge portions of the pattern portions, which have a relatively smaller radius of curvature, than at the center portions of the pattern portions, which have a larger radius of curvature.

[0059] Table 1 shows the thickness and total thickness of each configuration of exterior material A, exterior material B, exterior material C, and exterior material D. For example, exterior material A, exterior material B, and exterior material C may be manufactured by roll-to-roll using the A Lamination method, and exterior material D may be manufactured by roll-to-roll using the B Lamination method.

[0060] [Table 1]

[0061] Because existing batteries do not need to bend or deform, the mechanical properties of the exterior material that would be present if the exterior material were repeatedly folded were not considered important.

[0062] However, in an exterior material used in a flexible battery, the difference in mechanical properties of the exterior material that appears when the exterior material is repeatedly folded is more meaningful than the mechanical properties of the exterior material that appears when the exterior material is never folded.The direction in which the pattern portion is formed may be determined based on the direction of the pattern portion, that is, the mechanical properties of the exterior material when an exterior material including a pattern portion formed in the MD of the exterior material and an exterior material including a pattern portion formed in the TD of the exterior material are each repeatedly folded.

[0063] Flexible batteries are prone to breakage at the edges of the exterior pattern, which have the smallest relative radius of curvature. The smallest radius of curvature is the folded state, and the bending durability of flexible batteries can be easily determined by repeatedly folding the exterior material (accelerated test).

[0064] The following describes one method for evaluating the durability of exterior materials contained in a battery, which is a tensile test after repeated folding.

[0065] The configuration of the exterior material and the pattern portion are formed on the exterior material having different directions (MD, TD) and each of which is punched out into a sample with a certain width and length. For example, the exterior material can be punched out into a dumbbell shape with a width of 10 mm and a length of 100 mm.

[0066] Then, the center of each exterior material along its length is pressed and folded with the same pressure and time. For example, the exterior material can be pressed and folded with a pressure of 0.2 MPa for 2 seconds. Each exterior material can be folded and unfolded multiple times in the same manner.

[0067] A tensile tester can be used to fix a limit displacement in the length direction of the test piece and pull it at a constant deformation rate. For example, the length of the exterior material sample before tension can be 100 mm, and the length of the exterior material sample after tension can be 105 mm. The limit displacement can be 5 mm, and the deformation rate can be 5%.

[0068] For example, an exterior material in which a pattern portion is formed in the MD of the exterior material (MD pattern) can be folded in the MD and pulled in the TD. An exterior material in which a pattern portion is formed in the TD of the exterior material (TD pattern) can be folded in the TD and pulled in the MD.

[0069] After each packaging material was folded repeatedly the same number of times, the presence or absence of damage to the packaging material was confirmed using an electron microscope. Table 2 shows the results of the tensile test conducted on packaging materials A to D shown in Table 1 after the above-mentioned repeated folding.

[0070] [Table 2]

[0071] As shown in Table 2, when pulled after folding five times, no damage was found in any of the exterior material layers A, B, C, and D.

[0072] When folded 10 times and then pulled, the exterior material samples A, B, and C with a pattern formed in the MD did not break, but those with a pattern formed in the TD did break. The degree of breakage in the exterior material D sample with a pattern formed in the TD was also greater than that in the sample with a pattern formed in the MD.

[0073] When tension was applied after repeated folding 15 times, the degree of damage was greater in the exterior packaging materials A, B, and C where the pattern was formed in the TD than in the MD.

[0074] As described above, the tensile tests were performed on exterior packaging materials A, B, C, and D after repeated folding. As a result, it was found that the durability of exterior packaging materials A, B, C, and D when folded in MD and pulled in TD was higher than that when folded in TD and pulled in MD, i.e., the bending property and folding durability of the exterior packaging materials were higher.

[0075] By forming a pattern part on the MD of the exterior material, it is possible to minimize damage to the edge part of the pattern part, which has a small radius of curvature, and improve the bending durability of the battery.

[0076] Fig. 6 shows a graph of stress-strain. In the graph shown in Fig. 6, toughness indicates the area under the stress-strain curve.

[0077] Table 3 shows the results of evaluating the mechanical properties of exterior packaging material B after the tensile test described above was performed after repeated folding.

[0078] [Table 3]

[0079] Table 4 shows the results of evaluating the mechanical properties of exterior packaging material C after the tensile test described above was performed after repeated folding.

[0080] [Table 4]

[0081] Table 5 shows the results of evaluating the mechanical properties of exterior packaging material D after the tensile test described above was performed after repeated folding.

[0082] [Table 5]

[0083] Generally, exterior packaging materials manufactured by roll-to-roll process using Process A or Process B have excellent flexibility in the MD of the exterior packaging material and excellent rigidity in the TD of the exterior packaging material.

[0084] Referring to FIG. 6 and Tables 3 to 5, the greater the number of repeated folding times, the higher the toughness when a pattern portion is formed in the MD of the exterior packaging material is compared to the toughness when a pattern portion is formed in the TD. This confirms that in all of exterior packaging materials B, C, and D, when a pattern portion is formed in the MD of the exterior packaging material, the fatigue life of the exterior packaging material is longer.

[0085] The toughness of exterior material D when folded 0 times, i.e. when no repeated folding is performed, shows an opposite tendency to the toughness of exterior materials B and C when no repeated folding is performed. This is due to differences in the lamination method and internal materials, and for batteries that are repeatedly bent or deformed, the mechanical properties that change due to repeated deformation are more meaningful than the mechanical properties when no repeated folding is performed.

[0086] 7a is a diagram for explaining another method for evaluating the bending durability of a battery including a housing material. Referring to FIG. 7a, the bending evaluation can be performed by bending the battery 10 including the housing material 100 in one direction multiple times.

[0087] 7b, when the battery 10 including the outer casing 100 is bent, a force (710) acts on the inner bend diameter in a direction that contracts the outer casing 100, and a force (720) acts on the outer bend diameter in a direction that relaxes the outer casing 100. For the battery 10 including the outer casing 100 including the pattern portion 111md, bending evaluation may be performed on the TD of the outer casing. In other words, bending evaluation can be performed by bending the battery including the outer casing 100 in the length direction 10B of the battery.

[0088] Alternatively, a battery including an exterior material that includes the pattern portion 111td can be subjected to bending evaluation by bending the battery including the exterior material in the MD of the exterior material, that is, in the longitudinal direction 10B of the battery.

[0089] In one embodiment, bending evaluation may be performed by bending the battery under conditions of R15 and 25 rpm.

[0090] Table 6 shows the results of bending evaluation when a pattern portion is formed in the MD of the exterior material (MD pattern) and when a pattern portion is formed in the TD of the exterior material (TD pattern) for any of the exterior materials A, B, C, and D shown in Table 1. For example, Battery 1 in Table 6 means a battery including exterior material A in which a pattern portion is formed in the MD of the exterior material.

[0091] [Table 6]

[0092] According to the results of the bending evaluation of batteries 1 to 8 shown in Table 6, it was confirmed that in all of the exterior packaging materials A, B, C, and D, when a pattern portion was formed in the MD of the exterior packaging material, the degree of damage to the edge portions of the pattern portion was reliably reduced compared to when the pattern portion was formed in the TD of the exterior packaging material.

[0093] Therefore, by forming a pattern part in the MD of the exterior material, damage to the edge part of the pattern part of the exterior material can be minimized, electrolyte leakage and swelling phenomena can be reduced, and the bending durability and safety of the battery can be improved.

[0094] FIG. 8 is an exemplary diagram illustrating a method of forming a pattern on an exterior material according to an embodiment of the present invention.

[0095] In step S810, the packaging material 100 can be positioned between an upper mold and a lower mold.

[0096] In step S820, the exterior packaging material 100 is imprinted using an upper mold and a lower mold, so that at least one pattern portion 111md can be formed in the MD (Machine Direction) of the exterior packaging material 100.

[0097] Here, the MD of the outer casing may be the width direction of the battery including the outer casing, and the TD (Transverse Direction) of the outer casing may be the length direction of the battery including the outer casing.

[0098] In the above description, steps S810 to S820 may be further divided into additional steps or combined into fewer steps depending on the embodiment of the present invention. Also, some steps may be omitted as necessary, and the order of steps may be changed.

[0099] FIG. 9 is an exemplary diagram for explaining a method of producing a battery including an outer casing in one embodiment of the present invention.

[0100] In step S910, at least one pattern portion 111md may be formed on the outer casing 100 in the MD (Machine Direction) of the outer casing 100.

[0101] In step S920, the exterior material 100 on which the pattern portion 111md is formed may be folded.

[0102] In step S930, the electrode assembly 200 may be inserted into the folded outer casing 100.

[0103] For example, a pattern portion that contacts the upper surface of the battery and a pattern portion that contacts the lower surface of the battery are formed in the MD of the exterior material, and the exterior material can be folded in the TD of the exterior material based on the center line between the two pattern portions (folding operation). The exterior material folded based on the center line between the two pattern portions is positioned so that the pattern portion that contacts the upper surface of the battery and the pattern portion that contacts the lower surface of the battery are overlapped, and the electrode assembly may be inserted so as to be overlapped at the position of these pattern portions.

[0104] In another example, a sheath having a pattern portion formed in the MD of the sheath may be folded in the MD of the sheath, and the electrode assembly may be inserted into the folded sheath.

[0105] In step S940, the outer casing 100 into which the electrode assembly 200 has been inserted may be sealed. For example, the outer casing 100 may be sealed on four sides surrounding the outer casing 100 to generate four sealed regions, two of which may be formed in the MD of the outer casing 100 and the remaining two sealed regions may be formed in the TD of the outer casing 100.

[0106] Here, the MD of the outer casing may be the width direction of the battery including the outer casing, and the TD (Transverse Direction) of the outer casing may be the length direction of the battery including the outer casing.

[0107] In the above description, steps S910 to S940 may be further divided into additional steps or combined into fewer steps depending on the embodiment of the present invention. Also, some steps may be omitted as necessary, and the order of steps may be changed. In particular, the process of forming a pattern portion on an exterior material may be performed before or after sealing the exterior material in the present invention.

[0108] In the exterior packaging material according to the present invention, the fatigue life against deformation of the edge portion of the pattern portion may be set based on the pattern portion formed in the MD of the exterior packaging material. For example, the fatigue life against deformation of the edge portion of at least one pattern portion formed in the MD of the exterior packaging material may be longer than the fatigue life against deformation of the edge portion of the pattern portion of another exterior packaging material including at least one pattern portion formed in the TD of the exterior packaging material.

[0109] Thus, by including an exterior material having a pattern portion formed in the MD of the exterior material according to the present invention, the fatigue life of the edge portion of the pattern portion of the exterior material can be improved. Here, the fatigue life can mean the fatigue life against deformation caused by application of force to the edge portion of the exterior material, such as folding (e.g., folding the exterior material to create a battery), bending (e.g., bending the battery or the exterior material), and repeated folding (e.g., repeatedly folding the exterior material for an experiment on battery durability).

[0110] That is, the pattern part may be formed in the MD of the packaging material, taking into consideration the possibility of damage to the edge part of the pattern part of the packaging material. By forming the pattern part in the MD of the packaging material, it is possible to reduce the probability of damage to the edge part of the pattern having a relatively small radius of curvature in the pattern part of the packaging material.

[0111] As described above, a battery including a housing material having a pattern portion formed in the MD of the housing material can be applied to devices having a small bending radius and relatively high fatigue strength.

[0112] For example, the bending radius of the battery in the device is 5R (around the finger) to 35R (around the ankle), and the device can be applied to wrist bands, watches, ring-type smart devices, and the like.

[0113] The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described as a single type may be implemented in a distributed form, and similarly, each component described as a distributed type may be implemented in a combined form.

[0114] The scope of the present invention is indicated by the claims set forth below rather than by the detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalent concepts should be interpreted as being included within the scope of the present invention.

Claims

1. An exterior material for a battery, comprising: At least one pattern portion including a concave-convex shape in which each of the concave-convex shapes extends along the MD (Machine Direction) of the sheath material and the concave-convex shapes are alternately arranged along a direction intersecting the MD of the sheath material. Including, The MD of the exterior material is a width direction of the battery including the exterior material, The TD (Transverse Direction) of the exterior material is the length direction of the battery including the exterior material, The sealing portion further includes a sealing portion that surrounds the pattern portion and is joined to two surfaces of the exterior material to form a sealed space between the two surfaces, an edge portion of the pattern portion is located adjacent to the seal portion; An exterior material, wherein a radius of curvature for an edge portion of the pattern portion is smaller than a radius of curvature for a center portion of the pattern portion.

2. An exterior material for a battery, comprising: At least one pattern portion including a concave-convex shape in which each of the concave-convex shapes extends along the MD (Machine Direction) of the sheath material and the concave-convex shapes are alternately arranged along a direction intersecting the MD of the sheath material. Including, The MD of the exterior material is a width direction of the battery including the exterior material, The TD (Transverse Direction) of the exterior material is the length direction of the battery including the exterior material, The sealing portion further includes a sealing portion that surrounds the pattern portion and is joined to two surfaces of the exterior material to form a sealed space between the two surfaces, an edge portion of the pattern portion is located adjacent to the seal portion; The exterior material, wherein a radius of curvature of the pattern portion decreases from a center portion of the pattern portion toward an edge portion of the pattern portion.

3. The exterior packaging material according to claim 1 , wherein the edge portions of the pattern portion are formed on both sides of the pattern portion in the MD of the exterior packaging material, taking into consideration the possibility of breakage of the edge portions of the pattern portion.

4. 2. The exterior packaging material according to claim 1, wherein a fatigue life against deformation of an edge portion of the pattern portion is set based on the pattern portion extending along the MD of the exterior packaging material.

5. 5. The exterior packaging material according to claim 4, wherein the fatigue life against deformation of the edge portion of the pattern portion is longer than the fatigue life against deformation of the edge portion of a pattern portion of another exterior packaging material in which each of the projections and recesses extends along the TD of the exterior packaging material and the projections and recesses are alternately arranged along a direction intersecting the TD of the exterior packaging material.

6. The exterior material according to claim 1 or 2, which has a multi-layer structure in which at least one material is laminated.

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