Electrode current collector

Abstract

According to one embodiment of the present invention, there is provided a current collector for an electrode comprising: a base film; a conductive material layer including a conductive material formed on at least one of an upper surface or a lower surface of the base film; and an electrode active material formed on the surface of the conductive material layer, and the conductive material layer may include a peeling portion where the conductive material is not present or is formed by removing the conductive material so that the base film is exposed, and a current path portion located between the peeling portions and where the conductive material is present on the surface of the base film.

Description

[Technical field]

[0001] The present invention relates to a current collector for an electrode, and more particularly, to a current collector for an electrode that, when a short circuit occurs in a secondary battery including a current collector for an electrode by removing a part of a conductive material provided on a base film or removing a part of a conductive material and an electrode active material, exhibits an electrochemical or physical fuse function in which a short circuit current path is formed only in a part where the electrode active material and the conductive material are all present, allowing a short circuit current to flow, and the short circuit current path is blocked in the remaining part, thereby preventing overheating of the secondary battery when a short circuit occurs and improving the safety of the secondary battery. [Background technology]

[0002] As technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is rapidly increasing. Among such secondary batteries, lithium secondary batteries, which have high energy density, working potential, and low self-discharge rate, are being commercialized.

[0003] Lithium metal secondary batteries were the first commercialized secondary batteries, and use lithium metal as the anode. However, lithium metal secondary batteries have problems with cell volume expansion, gradual reduction in capacity and energy density, short circuiting due to the continued growth of dendrites, reduced cycle life, and cell stability (explosion and fire), and production was halted just a few years after commercialization. Therefore, instead of lithium metal, a carbon-based anode, which is more stable and can stably store lithium in an ionic state in the lattice or empty spaces, has been used, and the use of the carbon-based anode has led to the commercialization and widespread use of full-scale lithium secondary batteries.

[0004] To date, lithium secondary batteries have been dominated by carbon-based or non-carbon-based anode materials, with most anode material development focused on carbon-based (graphite, hard carbon, soft carbon, etc.) and non-carbon-based (silicon, tin, titanium oxide, etc.) materials.

[0005] Meanwhile, in recent years, as portable electronic devices and information and communication devices have become smaller, there are high expectations for the use of lithium secondary batteries as ultra-compact power supply systems for driving these devices.

[0006] Furthermore, in recent years, there has been active research and development of polymer-based electronic devices and elements that take advantage of their advantages such as flexibility, low cost, ease of fabrication, etc. Therefore, in order to use them in miniaturized devices, it is necessary to reduce the thickness or weight of the battery while maintaining the energy density or performance of the lithium secondary battery.

[0007] In addition, even if the thickness or weight of the lithium secondary battery is reduced, the safety of the lithium secondary battery must be improved by cutting off or destroying the current path when a short circuit occurs.

[0008] In particular, in the case of a large-capacity lithium secondary battery capable of storing energy of 2 Ah or more, a battery safety technology capable of reducing or cutting off the short circuit current when a short circuit occurs is even more necessary.

[0009] The present applicant has proposed the present invention in order to solve the above-mentioned problems. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 10-2006-0102745 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been proposed to solve the above problems, and provides a current collector for an electrode that can reduce thickness or weight compared to a current collector made of metal foil, and at the same time, can prevent overheating or temperature rise of a secondary battery by performing a fuse function when an internal or external short circuit occurs, thereby improving the stability of the battery.

[0012] In addition, the present invention provides an electrode current collector that, in the event of a short circuit in a large-sized lithium secondary battery, prevents the entire electrode current collector from reacting to the short circuit by isolating or separating the short-circuited portion from other portions, and allows the other portions of the electrode current collector excluding the short-circuited portion to operate normally.

[0013] In addition, the present invention provides an electrode current collector that can reduce the area or size of a short circuit occurring portion of an electrode current collector when a short circuit occurs in a large lithium secondary battery, thereby allowing energy to be dissipated only in a small portion of the electrode current collector, thereby reducing the amount of heat generated by the battery. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object, according to one embodiment of the present invention, a current collector for an electrode includes a base film, a conductive material layer including a conductive material formed on at least one of an upper surface or a lower surface of the base film, and an electrode active material formed on a surface of the conductive material layer, and the conductive material layer may include a peeling portion where the conductive material is not present or is formed by removing the conductive material so that the base film is exposed, and a current path portion located between the peeling portions and where the conductive material is present on the surface of the base film.

[0015] The peeling portion may be formed in a state in which the conductive material is not present or has been removed so that at least one of an upper surface and a lower surface of the base film is exposed, or may include the electrode active material formed on at least one of an upper surface and a lower surface of the base film that is exposed after the conductive material is not present or has been removed.

[0016] The current path part may be formed with the conductive material present on at least one of an upper surface and a lower surface of the base film.

[0017] The current path portion may include the electrode active material formed on a surface of the conductive material present on at least one of an upper surface and a lower surface of the base film.

[0018] The current path portion may be located between the peeling portions in a direction in which the peeling portions are arranged, or may be located between the peeling portions in a direction in which a pattern is formed by connecting the peeling portions and the current path portion.

[0019] The area of ​​the conductive material layer or the area of ​​the electrode active material may be divided into a number of reaction sections by pattern lines formed by connecting the peeling portion and the current path portion.

[0020] When a short circuit occurs in a secondary battery including the electrode current collector, a short circuit current may flow to the point where the short circuit occurs through the current path portion located around the point where the short circuit occurs.

[0021] The reaction section where the short circuit occurrence point is located among the reaction sections may become a fuse section that functions as an electrical fuse, and the entire current path portion forming the fuse section or the entire current path portion connected to the fuse section may be cut, and an electrochemical reaction of the electrode active material present in the fuse section may proceed in a state where all the current path portions are cut.

[0022] When the fuse section is formed or when all of the current path portions connected to the fuse section are cut, the fuse section is electrically disconnected, and an electrochemical reaction of the electrode active material present in the fuse section is induced, and a short-circuit current flows through the fuse section until the electrochemical reaction is completed.

[0023] The peeling portion and the current path portion, which form or surround the fuse section, may isolate the fuse section from the reaction section so that a short-circuit reaction due to a short-circuit current occurs only in the fuse section, or may isolate or separate the fuse section participating in the short-circuit reaction from the reaction section.

[0024] The peeling portion may be formed on a same line among the pattern lines formed by connecting the peeling portion and the current path portion, and at least one current path portion may be formed on the same line, and the peeling portion and the current path portion positioned on the same line may be formed to have different lengths or sizes.

[0025] The base film may be made of a transparent material.

[0026] The peeling portion and the current path portion may be formed symmetrically on the upper and lower surfaces of the base film.

[0027] The peeling portion and the current path portion may be formed symmetrically on the upper and lower surfaces of the base film by laser patterning. Effect of the Invention

[0028] The electrode current collector according to the present invention uses a base film made of a non-conductor instead of a metal foil, and a conductive material is coated or plated on the surface of the base film, so that the thickness can be reduced compared to a current collector made of a metal foil.

[0029] If a short circuit occurs in a secondary battery including the electrode current collector according to the present invention, the part of the electrode current collector where the short circuit has occurred can be isolated from other parts to block the short circuit current flowing through the part where the short circuit has occurred, thereby reducing the part of the electrode current collector involved in the short circuit.

[0030] The electrode current collector according to the present invention has a structure equivalent to a plurality of divided electrode current collectors electrically connected in parallel to lead tabs. Therefore, by separating only the divided portion of the electrode current collector where a short circuit has occurred and interrupting the short circuit current, the remaining portion of the electrode current collector can continue to be used, thereby improving the safety of the secondary battery and extending its service life.

[0031] The electrode current collector according to the present invention performs an electrochemical or physical fuse function by inducing a short circuit current to flow only in a current path around a part where a short circuit has occurred among a plurality of divided electrode current collectors, and by blocking the current path so that a short circuit current does not flow to other parts where no short circuit has occurred, thereby preventing overheating of a battery and improving the safety of a secondary battery.

[0032] When the electrode current collector according to the present invention is applied to a large lithium secondary battery, if a short circuit occurs in the secondary battery, the area or size of the short circuit occurring portion of the electrode current collector can be reduced so that energy is dissipated only in a small portion of the electrode current collector, thereby reducing the amount of heat generated by the secondary battery. [Brief description of the drawings]

[0033] [Figure 1] 1 is a perspective view illustrating an electrode assembly including a current collector for an electrode according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view showing the electrode assembly shown in FIG. [Diagram 3] 1A to 1C are diagrams illustrating an electrode current collector according to an embodiment of the present invention and a manufacturing process thereof. [Figure 4] 1A to 1C are diagrams illustrating an electrode current collector according to an embodiment of the present invention and a manufacturing process thereof. [Diagram 5] 1A to 1C are diagrams illustrating an electrode current collector according to an embodiment of the present invention and a manufacturing process thereof. [Figure 6] 1A to 1C are diagrams illustrating an electrode current collector according to an embodiment of the present invention and a manufacturing process thereof. [Figure 7] 6 is a cross-sectional view showing the electrode current collector shown in FIG. 5 cut in a direction perpendicular to a peeled portion. [Figure 8] 6 is a cross-sectional view showing the electrode current collector shown in FIG. 5 cut in a direction perpendicular to a peeled portion. [Figure 9] FIG. 13 is a diagram showing a modified example of an electrode current collector according to one embodiment of the present invention. [Figure 10] FIG. 13 is a diagram showing a modified example of an electrode current collector according to one embodiment of the present invention. [Figure 11] 1 is a diagram for explaining the function of an electrode current collector when a short circuit occurs in a lithium secondary battery including the electrode current collector according to one embodiment of the present invention. FIG. [Figure 12] 1 is a diagram for explaining the function of an electrode current collector when a short circuit occurs in a lithium secondary battery including the electrode current collector according to one embodiment of the present invention. FIG. [Figure 13] 1 is a diagram for explaining the function of an electrode current collector when a short circuit occurs in a lithium secondary battery including the electrode current collector according to one embodiment of the present invention. FIG. [Figure 14] 1 is a diagram for explaining the function of an electrode current collector when a short circuit occurs in a lithium secondary battery including the electrode current collector according to one embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or restricted by the preferred embodiments. The same reference numerals in the drawings refer to the same elements.

[0035] FIG. 1 is a perspective view showing an electrode assembly including an electrode current collector according to one embodiment of the present invention, FIG. 2 is an exploded perspective view showing the electrode assembly according to FIG. 1, FIGS. 3 to 6 are figures for explaining an electrode current collector according to one embodiment of the present invention and its manufacturing process, FIGS. 7 and 8 are cross-sectional views showing the electrode current collector shown in FIG. 5 cut in a direction perpendicular to the peeling portion, FIGS. 9 and 10 are figures showing modified examples of an electrode current collector according to one embodiment of the present invention, and FIGS. 11 to 14 are figures for explaining the function of the positive electrode current collector when a short circuit occurs in a lithium secondary battery equipped with an electrode current collector according to one embodiment of the present invention.

[0036] The electrode current collector according to the present invention is a concept including not only a positive electrode current collector used in a secondary battery, but also a negative electrode current collector. For convenience of explanation, the following will exemplarily explain a case where the electrode current collector is a positive electrode current collector.

[0037] 1 and 2 show an electrode assembly 10 including an electrode current collector 100 according to an embodiment of the present invention. In the case of Fig. 1 and Fig. 2, the electrode current collector 100 according to an embodiment of the present invention is a positive electrode current collector, and in order to be used in the electrode assembly 10, a positive electrode active material 103 must be coated or applied to the surface of the electrode current collector 100.

[0038] Meanwhile, the negative electrode current collector 200 may be formed by coating or applying a negative electrode active material 203 on a negative electrode metal foil 201, and a negative electrode lead tab 290 may be connected to one end of the negative electrode in the longitudinal direction.

[0039] A separator 300 may be disposed between the negative electrode current collector 200 and the electrode current collector 100 according to an embodiment of the present invention. When the negative electrode current collector 200 and the electrode current collector 100 are stacked in order on the upper and lower sides of the separator 300 as shown in Fig. 2, the electrode assembly 10 as shown in Fig. 1 is obtained.

[0040] For ease of explanation, the following description will be centered on the case where the electrode current collector 100 is a positive electrode current collector.

[0041] 3 to 14 show a positive electrode current collector 100 according to one embodiment of the present invention. Unlike the negative electrode current collector 200 mentioned above, the positive electrode current collector 100 does not use a metal foil.

[0042] A current collector for electrode (100) according to an embodiment of the present invention has a resistance value greater than that of a current collector made of a metal foil, so that the limiting current value of the current flowing through the current collector for an electrode can be adjusted. In addition, when an internal short circuit occurs in a secondary battery, the short circuit current can be reduced or heat generation can be reduced because the flow of current can be obstructed due to damage to the base film.

[0043] A lithium secondary battery including the electrode current collector 100 according to one embodiment of the present invention may have the characteristics or concept of a Max Current Limited Battery (MCLB).

[0044] Hereinafter, a current collector 100 for an electrode according to one embodiment of the present invention that enables realization of MCLB will be described.

[0045] The electrode current collector 100 according to one embodiment of the present invention is a positive electrode current collector, Since the positive electrode current collector of the existing secondary battery has a higher resistance than the resistance of the positive electrode current collector made of metal foil, the limiting current can be adjusted, and when an internal short circuit occurs, the current path is cut off or collapsed, thereby reducing the short circuit current or reducing the heat generation that occurs when a short circuit occurs, thereby improving the safety of the secondary battery.

[0046] One feature of the electrode current collector 100 according to one embodiment of the present invention is that it uses a base film 101 as a basic material without using a metal foil, and applies or coats a thin layer of metal onto the base film 101.

[0047] 3 to 8, a current collector 100 for an electrode according to one embodiment of the present invention may include a base film 101, a conductive material layer 102 including a conductive material formed on at least one of the upper and lower surfaces of the base film 101, and an electrode active material 103 formed on the surface of the conductive material layer 102.

[0048] Here, the conductive material layer 102 may include peeling portions (portions without conductive material) 160 formed by removing or eliminating conductive material so as to expose the surface of the base film 101, and current path portions (portions through which current flows) 170 located between the peeling portions 160 along the arrangement or pattern direction of the peeling portions 160. In the above, the electrode active material 103 may be coated or applied so as to cover the peeling portions 160 of the conductive material layer 102 where no conductive material exists.

[0049] 3, 4, 7 and 8, a current collector 100 for an electrode according to an embodiment of the present invention may include a base film 101 which is the basis of the current collector 100, a conductive material layer 102 formed on at least one of an upper surface or a lower surface of the base film 101, and an electrode active material 103 formed on a surface of the conductive material layer 102.

[0050] If the electrode current collector 100 is a current collector for a positive electrode or cathode, the conductive material layer 102 is formed by coating a conductive material made of aluminum (Al) metal, and the electrode active material 103 may be an active material for a positive electrode.

[0051] On the other hand, when the electrode current collector 100 is a current collector for a negative electrode or anode, the conductive layer 102 is formed by coating with copper (Cu) metal, and the electrode active material 103 may be an active material for a negative electrode.

[0052] FIG. 3 is a plan view of a positive electrode current collector 100 in a state in which a conductive material layer 102 made of an aluminum metal conductive material is formed on the surface of a base film 101, and FIG. 4 is a plan view of the positive electrode current collector 100 in a state in which an electrode active material (positive electrode active material 103) is formed on the surface of the conductive material layer 102 in the state shown in FIG. 3.

[0053] The electrode current collector 100 according to one embodiment of the present invention may be used in a state where a part of the conductive material forming the conductive material layer 102 is removed, or where all of the conductive material and part of the electrode active material 103 are removed, instead of using the positive electrode current collector 100 shown in FIG. 4 as is.

[0054] The base film 101 may be provided in a strip shape having a certain length. Here, the base film 101 should be made of a non-conductive material such as polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), polymethylpentene (PMP), or polyethylene terephthalate (PET).

[0055] The base film 101 has a thickness of 50 μm or less, and preferably has a thickness of 1.4 μm to 50 μm. The positive electrode current collector 100 according to one embodiment of the present invention can reduce the thickness or weight of a battery compared to a case where a conventional metal foil current collector is used, and by using the non-conductive base film 101 having a thickness of 1.4 μm to 50 μm as a basic component of the positive electrode current collector 100, the overall thickness or weight of a lithium secondary battery including the positive electrode current collector 100 according to one embodiment of the present invention can be reduced.

[0056] In addition, in the electrode current collector 100 according to an embodiment of the present invention, in a state shown in FIG. 3, i.e., in a state where the conductive material layer 102 is formed (coated or applied) on the upper or lower surface of the base film 101, a part of the conductive material forming the conductive material layer 102 is removed to form a peeling part 160, and then an electrode active material 103 is formed on the upper surface of the peeling part 160 so as to cover the peeling part 160; or in a state shown in FIG. 4, i.e., in a state where the conductive material layer 102 and the electrode active material 103 are both formed on the upper or lower surface of the base film 101, a part of the conductive material and the electrode active material 103 should be removed all at once to form the peeling part 160, so that it is preferable that the base film 101 is formed to a thickness of 7 μm or more and 50 μm or less. In this way, only when the thickness of the base film 101 is 7 μm or more and 50 μm or less can the base film 101 maintain its original shape without melting or breaking during the process of removing only the conductive material of the conductive material layer 102 or removing the conductive material and the electrode active material 103 at once to form the peeling portion 160.

[0057] The inventors of the present invention have conducted repeated experiments to determine the optimal thickness of the base film 101 of the electrode current collector 100 according to one embodiment of the present invention, and the results are shown in the following [Table 1] and [Table 2].

[0058] [Table 1]

[0059] [Table 1] shows the results of an experiment conducted to determine whether a positive electrode current collector, in which a conductive layer made of an aluminum conductive material is coated or applied on the upper or lower surface of a base film 101, is cut when a peeled portion is formed by removing the aluminum conductive material using a laser. The photographs show positive electrode current collectors with base film thicknesses of 5 μm (Experiment 1), 7 μm (Experiment 2), and 12 μm (Experiment 3) in which a peeled portion is formed by removing the aluminum conductive material using a laser under conditions of a laser power of 60% and a speed of 300 mm / s. Referring to [Table 1], in Experiment 1, the base film was completely cut at the portion where the peeled portion was formed. Meanwhile, in Experiments 2 and 3, the base film was not cut at the portion where the peeled portion was formed.

[0060] [Table 2]

[0061] [Table 2] shows photographs of the peeled part of the positive electrode current collector in experiment 2, where the base film was 7μm thick, and photographs of the peeled part of the positive electrode current collector in experiment 3, where the base film was 12μm thick. Looking at the photographs of the peeled parts (a) and (b) observed under a loupe in experiment 2, and the photographs of the peeled parts (c) and (d) observed under a loupe in experiment 3, it can be seen that the base film is connected without being cut or melted, and the shape of the positive electrode current collector is maintained.

[0062] [Table 3]

[0063] Experiment 4 in Table 3 shows the results of an experiment to determine whether a negative electrode current collector, in which a conductive layer of copper conductive material is coated or applied to the upper or lower surface of the base film 101, breaks when a peeling portion is formed using a laser. The photographs show a negative electrode current collector with a base film thickness of 7 μm, in which a peeling portion is formed by removing the copper conductive material with a laser under conditions of a laser power of 60% and a speed of 300 mm / s, and a photograph of the peeling portion observed with a loupe. In the case of experiment 4, the photograph of the peeling portion observed with a loupe shows that the base film is either broken or connected without melting, and the shape of the negative electrode current collector is maintained.

[0064] As can be seen from [Table 1] to [Table 3], in the electrode current collector 100 according to one embodiment of the present invention, when the base film 101 is formed to a thickness of 7 μm or more and 50 μm or less, it can be confirmed that the current collector 100 has a tensile strength that allows a process of forming a peeling portion by a laser.

[0065] When forming the peeling portion using a laser, the property of the laser that can penetrate transparent materials may be utilized, so if the base film is made of a transparent material, only the metal and electrode parts can be melted, and the transparent parts, i.e., the base film made of a transparent material, can be maintained without melting because the laser penetrates through them. However, the heat generated when the metal and electrode parts melt may affect the base film made of a transparent material, and the thinner the base film, the greater the effect, and the base film may be cut. Therefore, when forming the peeling portion using a laser, the base film should be made of a transparent material, and it is preferable that the base film has a thickness of 7 μm or more and 50 μm or less.

[0066] 3, 4, 7 and 8, a current collector 100 for an electrode according to one embodiment of the present invention may include a base film 101 and a conductive material layer 102 provided on a surface (upper or lower surface) of the base film 101.

[0067] When the electrode current collector 100 is a positive electrode current collector, the conductive material layer 102 may be made of a conductive material such as aluminum (Al) metal.

[0068] The conductive material layer 102 may be formed to adjust or lower a limit current or a maximum current of the electrode current collector 100. When the electrode current collector 100 is a positive electrode current collector, the conductive material layer 102 may include a conductive material of aluminum metal plated or coated on a surface (at least one of the upper surface or the lower surface) of the base film 101 to control the conductivity of the positive electrode current collector 100. Hereinafter, the conductive material layer 102 is a concept including a conductive material.

[0069] By adjusting the coating amount or coating thickness of the conductive layer 102 plated (coated) or evaporated on the surface of the base film 101, the maximum amount of current flowing through the electrode collector 100 can be controlled or reduced, thereby improving the safety of the lithium secondary battery and ensuring the safety of the lithium secondary battery in the event of a short circuit.

[0070] In other words, the limit current or maximum current flowing through the electrode current collector 100 may be adjusted depending on the thickness or amount of the conductive material layer 102 formed on the surface of the base film 101. In this manner, the conductive material layer 102 of the electrode current collector 100 according to one embodiment of the present invention may embody the characteristics or concept of a Max Current Limited Battery (MCLB) of a lithium secondary battery.

[0071] In addition, when a physical internal or external short circuit occurs, the base film 101 may melt, preventing the generation of a sudden current, thereby improving the safety of the battery.

[0072] The conductive material layer 102 may be formed on the surface of the base film 101 by various methods. For example, in the case of a positive electrode current collector, the conductive material layer 102 may be obtained by forming an aluminum metal conductive material on at least one of the upper and lower surfaces of the base film 101 by sputtering or evaporation coating. Since aluminum oxidizes easily, it is not easy to form the conductive material layer 102 on the surface of the base film 101 by electrolytic plating.

[0073] Since the conductive layer 102 can control the conductivity of the electrode current collector 100 or ensure the safety of the battery depending on the amount (weight) or thickness of the conductive material to be coated, it is necessary to use a plating or coating method that can control or adjust the thickness or amount (weight) of the conductive layer 102.

[0074] The conductive layer 102 may be formed on only one of the upper and lower surfaces of the base film 101, or on both surfaces. In this case, the conductive layer 102 is preferably formed to a thickness of 0.3 μm on a minimum cross-sectional basis and 2.5 μm on a maximum cross-sectional basis.

[0075] In the electrode current collector 100 according to an embodiment of the present invention, since current can flow through the conductive material layer 102, the conductive material layer 102 must be well maintained as coated or applied on the surface of the base film 101. For this reason, it is preferable to perform a surface treatment on the base film 101 to increase the adhesive strength between the conductive material layer 102 and the base film 101.

[0076] If the adhesion between the conductive layer 102 and the base film 101 is not good, the conductive layer 102 may separate or detach from the surface of the base film 101 when the electrolyte is injected, so it is important to increase the adhesion between the conductive layer 102 and the base film 101.

[0077] The surface of the base film 101 may be subjected to a surface treatment in order to enhance the adhesive force or binding force with the conductive layer 102 .

[0078] In order to increase the bonding strength between the conductive layer 102 and the base film 101, it is preferable to subject the surface of the base film 101 to a corona treatment.

[0079] 3 and 4, the current collector 100 for an electrode according to an embodiment of the present invention may include a lead tab 190 for electrical connection with an external device.

[0080] Existing electrode current collectors made of metal foils allow lead tabs to be welded directly to the metal foil, but since electrode current collector 100 according to one embodiment of the present invention uses base film 101 instead of the existing metal foil, it is impossible or difficult to weld lead tabs directly to base film 101.

[0081] The electrode current collector 100 according to one embodiment of the present invention can solve this problem by further positioning metal pieces 120 on both sides of the base film 101 or on one side to which the lead tab 190 is connected, and welding the lead tab 190 to the metal pieces 120.

[0082] The lead tab 190 can be connected to the electrode current collector 100 by positioning the metal piece 120 on one side to which the lead tab 190 is attached or on both sides of the base film 101 and welding the lead tab 190 to the metal piece 120. The lead tab 190 cannot be connected unless the base film 101 melts at a temperature lower than the welding temperature of the lead tab 190. Therefore, it is preferable that the base film 101 has a melting point high enough to be melted in the process of welding the lead tab 190.

[0083] The metal piece 120 may be provided on only one of both sides of the base film 101 as shown in FIGS. 3 and 4, or may be provided on both sides of the base film 101.

[0084] The metal piece 120 may serve to secure a position for welding the lead tab 190 on the base film 101. That is, the metal piece 120 may serve as a connecting portion for the lead tab 190.

[0085] The metal piece 120 is preferably formed to have a thickness of 5 μm or more.

[0086] As described above, the metal piece 120 is preferably in the form of a thin metal film or metal foil having a thickness of 5 μm or more, but is not necessarily limited to such a form. That is, the metal piece 120 may be provided in the form of a thin film, foil, or mesh.

[0087] The metal piece 120 is preferably made of aluminum foil or SUS 316L foil in the case of a positive electrode, and is preferably made of Cu, Ni, or SUS foil in the case of a negative electrode.

[0088] In the electrode current collector 100 according to one embodiment of the present invention, the lead tab 190 may be welded to the metal piece 120 by ultrasonic welding, laser welding, or spot welding.

[0089] A metal piece 120 for connecting the lead tab 190 may be provided on only one surface of the base film 101. In this case, the conductive material layer 102 may be located between the lead tab 190 and the metal piece 120. That is, the conductive material layer 102 may be applied or coated on the upper and lower surfaces of the base film 101 first, and then the metal piece 120 may be located on the conductive material layer 102 so as to be electrically connected to the conductive material layer 102, or the metal piece 120 may be provided so as to contact the conductive material layer 102.

[0090] When the lead tab 190 is welded to the metal piece 120 provided on at least one of both sides of the base film 101, the base film 101 melts, thereby connecting the metal pieces 120 provided on both sides of the base film 101 to each other, and as a result, the lead tab 190 may be electrically connected to the conductive layers 102 provided on both sides of the base film 101 at the same time.

[0091] When the lead tab 190 is ultrasonically welded, laser welded or spot welded to the metal piece 120 provided on the upper surface of the base film 101 with the metal piece 120 and the conductive layer 102 provided on both the upper and lower surfaces of the base film 101, a part of the base film 101 may melt. If the temperature of the welding heat generated when welding the lead tab 190 is higher than the melting point of the base film 101, the base film 101 may melt during the welding process.

[0092] In this manner, since the base film 101 is not present in the melted portion, the upper and lower metal pieces 120 may come into direct contact with each other. At this time, since the metal pieces 120 are also in a melted state due to the welding heat, the upper and lower metal pieces 120 are joined to each other. Therefore, since the upper and lower metal pieces 120 are directly fused and joined to each other in the portion where the base film 101 is melted away, the lead tab 190 welded to any one of the metal pieces 120 may be electrically connected not only to the upper and lower metal pieces 120 but also to the conductive material of the conductive material layer 102 formed on the upper and lower surfaces of the base film 101.

[0093] In the electrode current collector 100 according to one embodiment of the present invention, the metal piece 120 remains connected to the base film 101 even if a portion of the base film 101 melts due to welding heat, so that the lead tab 190 can be connected.

[0094] However, in some cases, lead tab 190 can be welded to metal piece 120 even when base film 101 is not melted.

[0095] Meanwhile, in the electrode current collector 100 according to an embodiment of the present invention, the electrode active material 103 may be applied to the surface of the conductive material layer 102. After the electrode active material 103 is applied to the surface of the conductive material layer 102, a press process is performed on the surface of the electrode active material 103 to firmly bond the conductive material layer 102 and the electrode active material 103.

[0096] In the electrode current collector 100 according to one embodiment of the present invention, the maximum amount of current flowing through the electrode current collector 100 can be controlled or reduced by adjusting the thickness or amount of the conductive material layer 102 formed on the upper or lower surface of the base film 101. This not only enhances the safety of a lithium secondary battery including the electrode current collector 100, but also provides a peeling section 160 and a current path section 170, which will be described later, to isolate a portion where a short circuit occurs from other portions, thereby reducing a temperature rise during a short circuit and preventing the lithium secondary battery from exploding.

[0097] 5 to 14, a current collector 100 for an electrode according to one embodiment of the present invention may include peeled portions 160 formed by removing a conductive material of a conductive material layer 102 provided on an upper or lower surface of a base film 101, and current path portions 170 located between adjacent peeled portions 160.

[0098] The peeling part 160 is a part formed by removing a part of the conductive material of the conductive material layer 102 formed on the surface of the base film 101, and is a part where the surface of the base film 101 is exposed because there is no conductive material layer 102 or conductive material. The current path part 170 is a part located between adjacent peeling parts 160, and is a part where the surface of the base film 101 is not exposed because the conductive material 102 and the electrode active material 103 exist in their original state.

[0099] Here, the peeling portion 160 may be provided in two forms, one of which is a case where only the conductive material of the conductive material layer 102 formed on the surface of the base film 101 is removed, and the electrode active material 103 remains as it is without being removed. That is, after the conductive material of the conductive material layer 102 formed on the surface of the base film 101 is partially removed, the electrode active material 103 is formed on the surface of the conductive material layer 102 in that state. In this case, the surface of the base film 101 located at the peeling portion 160 is covered with the electrode active material 103. That is, the electrode active material 103 covers the peeling portion 160.

[0100] Another form of the peeling portion 160 is a form in which the conductive material of the conductive material layer 102 formed on the surface of the base film 101 and a part of the electrode active material 103 are removed all at once. In this case, the surface of the base film 101 located at the peeling portion 160 is exposed. That is, the surface of the base film 101 is exposed through the peeling portion 160.

[0101] 5 to 14, when the peeling portion 160 and the current path portion 170 are connected to each other, a certain pattern is formed. As shown in Fig. 4, in a state where the conductive material layer 102 and the electrode active material 103 are all applied to the surface of the base film 101, the conductive material of the conductive material layer 102 and the electrode active material 103 are removed together according to a certain pattern to form the peeling portion 160, thereby obtaining the electrode current collector 100 shown in Figs. 5 to 14.

[0102] As described above, the peeling portion 160 may be formed in a state where the conductive material and the electrode active material 103 of the conductive material layer 102 are removed all at once, exposing the base film 101, or in a state where only the conductive material is removed and the electrode active material 103 covers the area where the conductive material was removed, so that the base film 101 is not exposed.

[0103] Meanwhile, in the current path portion 170 located between the peeling portions 160, the electrode active material 103 and the conductive material layer 102 are all present, or the electrode active material 103 is not present but the conductive material layer 102 is present, so the surface of the base film 101 is not exposed. That is, since at least the conductive material layer 102 is present in the current path portion 170, the base film 101 is not exposed. When such an electrode current collector 100 is used in a lithium secondary battery, current does not flow through the peeling portion 160 where the conductive material of the conductive material layer 102 is not present but the electrode active material 103 is present, and through the peeling portion 160 where neither the electrode active material 103 nor the conductive material is present. Current flows only through the current path portion 170 where at least the conductive material layer 102 is present.

[0104] At this time, in the peeling portion 160 where there is no conductive material layer 102 and only the electrode active material 103, a weak current may flow due to the resistance of the electrode active material 103. However, when the electrode current collector 100 according to one embodiment of the present invention is a positive electrode current collector, the resistance of the positive electrode active material is high, so that the amount of current that can flow through the positive electrode active material 103 that is not a conductive material layer is very small.

[0105] The electrode current collector 100 shown in Fig. 5 has two peeling parts 160 formed on both sides along the width direction of the base film 101, and one current path part 170 formed between the peeling parts 160. When the peeling parts 160 and the current path part 170 are connected, a linear pattern is formed. The electrode current collector 100 may be divided into left and right sides based on this linear pattern. When the electrode current collector 100 is used in a lithium secondary battery, current flows to both the left and right sides of the pattern through the current path part 170.

[0106] The electrode current collector 100 shown in Fig. 6 has six peeling parts 160 formed along the width direction of the base film 101, and five current path parts 170 formed between the peeling parts 160. When the peeling parts 160 and the current path parts 170 are connected, a linear pattern is formed. Similarly, when the electrode current collector 100 is used in a lithium secondary battery, current flows to both the left and right sides of the pattern through the current path parts 170. In the case of Fig. 6, the peeling parts 160 are formed in the form of dotted lines.

[0107] 7 and 8 show cross-sectional views of the electrode current collector 100 shown in Fig. 5. Fig. 7 shows a cross-section of the electrode current collector 100 in which the conductive material layer 102 and the electrode active material 103 are all formed on the upper and lower surfaces of the base film 101 and the peeling portion 160 is formed. In the case of Fig. 7, the peeling portion 160 is in a state in which the conductive material layer 102 and the electrode active material 103 have all been removed, so that the surface of the base film 101 at the position of the peeling portion 160 is exposed. In other words, the surface of the base film 101 is exposed through the peeling portion 160.

[0108] 8 shows a peeling portion 160 in which the conductive material layer 102 has been removed and is absent, and only the electrode active material 103 is present. When the electrode current collector 100 according to an embodiment of the present invention is a positive electrode current collector as shown in FIG 8, the resistance of the positive electrode active material 103 is high, so that the amount of current that flows through the positive electrode active material 103 other than the conductive material layer is very small.

[0109] When the conductive material layer 102 and the electrode active material 103 are formed on both the upper and lower surfaces of the base film 101, it is preferable that the peeling portion 160 is formed symmetrically on the upper and lower surfaces of the base film 101.

[0110] According to an embodiment of the present invention, the electrode current collector 100 shown in FIG. 4 may be patterned using a laser to form a peeling portion 160 and a current path portion 170.

[0111] In order to remove the conductive material layer 102 and the electrode active material 103 on the upper and lower surfaces of the base film 101, the upper surface of the base film 101 must be irradiated with a laser to form the peeling portion 160 on the upper surface, and the lower surface of the base film 101 must be irradiated with a laser to form the peeling portion 160 on the lower surface. That is, the upper and lower surfaces of the base film 101 must be irradiated with a laser, respectively, which is not efficient in terms of process. In order to improve process efficiency, in the electrode current collector 100 according to an embodiment of the present invention, the base film 101 is prepared from a transparent material, and if a laser is irradiated on either the upper or lower surface of the base film 101, the laser can pass through the base film 101 made of a transparent material, and the peeling portion 160 can be formed simultaneously on the opposite surface to the irradiated surface. That is, since the base film 101 is transparent, the laser can pass through the base film 101 to form the peeling portion 160 and the current path portion 170 symmetrically on both the upper and lower surfaces of the base film 101.

[0112] In addition, in the electrode current collector 100 according to one embodiment of the present invention, the base film 101 is made of a transparent material and has a thickness of 7 μm or more and 50 μm or less, so that the base film 101 can be prevented from being melted or cut by a laser.

[0113] Moreover, the base film 101 of the electrode current collector 100 according to one embodiment of the present invention is preferably made of a material having a melting point high enough not to melt even when irradiated with a laser.

[0114] As described above, in the case of the electrode current collector 100 according to one embodiment of the present invention, the peeling portion 160 and the current path portion 170 may be formed symmetrically on the upper and lower surfaces of the base film 101 by laser patterning. The peeling portion 160 and the current path portion 170 may be formed symmetrically on the upper and lower surfaces of the base film 101.

[0115] If the conductive material layer 102 and the electrode active material 103 are formed on only one of the upper and lower surfaces of the base film 101, the peeling portion 160 and the current path portion 170 may be formed on only one side of the base film 101.

[0116] 9, a peeling portion 160 and a current path portion 170 are formed along the longitudinal direction of a base film 101. In the case of FIG. 9, the peeling portion 160 and the current path portion 170 may also be formed in a portion where a lead tab 190 is connected.

[0117] 10, a peeling portion 160 and a current path portion 170 are formed in a mesh (lattice) shape over the entire area of ​​an electrode active material 103 applied to a base film 101. In the case of FIG. 10, the peeling portion 160 and the current path portion 170 may also be formed in a portion where a lead tab 190 is connected.

[0118] The peeling portion 160 and the current path portion 170 of the electrode current collector 100 shown in FIGS. 5 to 10 may be formed symmetrically on the upper and lower surfaces of the base film 101 by laser patterning.

[0119] 5 to 10 are used as battery elements constituting a lithium secondary battery, the battery operates without any problems because current flows through the current path portion 170, the electrode active material 103 connected to the current path portion 170, and the conductive material of the conductive material layer 102.

[0120] If a short circuit occurs in a lithium secondary battery in which the electrode current collector 100 according to one embodiment of the present invention is used as a battery element, the peeling portion 160 and the current path portion 170 can minimize the area where the short circuit occurs, or can isolate or separate the area where the short circuit does not occur from the area where the short circuit occurs, thereby ensuring the safety of the battery.

[0121] Hereinafter, with reference to Figs. 11 to 14, the function of the electrode current collector 100 in the case where a short circuit occurs in a lithium secondary battery in which the electrode current collector 100 according to one embodiment of the present invention is used as a battery element will be described.

[0122] 11, in the electrode current collector 100, the area of ​​the conductive material layer 102 or the electrode active material 103 may be divided into two reaction sections 105 on both sides by a linear pattern line formed by connecting the peeling portion 160 and the current path portion 170. That is, the conductive material layer 102 or the electrode active material 103 may be divided into two reaction sections 105 on both sides based on the pattern line connecting the peeling portion 160 and the current path portion 170. Here, the reaction sections 105 may be regarded as regions formed by dividing the region of the electrode current collector 100.

[0123] If a short circuit occurs in the left reaction section 105 based on the pattern line of the electrode current collector 100 shown in FIG. 11, the electrical resistance of the short circuit occurrence point S or the reaction section 105 including the short circuit occurrence point S will become small, and a short circuit current will flow to the reaction section 105 where the short circuit occurrence point S is located.

[0124] However, in a reaction section 105 where no short circuit occurs, the current flowing through the reaction section 105 including the short circuit occurrence point S can only pass through the current path part 170. In other words, when a short circuit occurs in a secondary battery including an electrode current collector, the short circuit current may flow to the short circuit occurrence point S through the current path part 170 located around the short circuit occurrence point S, or may flow to the reaction section 105 including the short circuit occurrence point S.

[0125] Here, the pattern line connecting the peeling portion 160 and the current path portion 170 located around the short circuit occurrence point S may form a fuse section 106 surrounding the short circuit occurrence point S. That is, among the reaction sections 105 divided by the pattern line, the reaction section 105 including the short circuit occurrence point S may become the fuse section 106 that functions or operates as an electrical fuse.

[0126] The entire current path portion 170 forming the fuse section 106 or the entire current path portion 170 connected to the fuse section 106 is cut off. Only when all current path portions 170 forming the fuse section 106 or connected to the fuse section 106 are cut off, the fuse section 106 is electrically disconnected and an electrochemical reaction can proceed only in the fuse section 106. After all current path portions 170 are cut off, a short-circuit current flows only in the fuse section 106, which induces an electrochemical reaction of the electrode active material 103 present in the fuse section 106, and the short-circuit current flows through the fuse section 106 until the electrochemical reaction is completed. In the case of FIG. 11, the left reaction section including the short-circuit occurrence point S becomes the fuse section 106, and a short-circuit current flows through the fuse section 106 through one current path portion 170. At this time, the reaction section 105 located on the right side of the pattern line does not react to or participate in the short circuit.

[0127] As a short circuit current flows intensively through the current path portion 170 connected to the fuse section 106, the temperature of the current path portion 170 may rise, causing the current path portion 170 to break. When the current path portion 170 breaks, only the fuse section 106 reacts to the short circuit, so that the entire electrode current collector 100 reacts to the short circuit, generating a lot of heat, and thus preventing accidents such as a battery explosion. Also, as only the fuse section 106 reacts to the short circuit due to the peeling portion 160, the remaining reaction sections 105 that have not reacted to the short circuit can normally function as a battery to a certain extent. Here, reacting to a short circuit means that a short circuit current flows.

[0128] If a short circuit occurs in reaction section 105 located in the upper left corner of electrode current collector 100 shown in FIG. 12, the electrical resistance between the short circuit point S or reaction section 105 including the short circuit point S and the other short-circuited electrode becomes small, and a short circuit current flows through reaction section 105 including the short circuit point S. At this time, if a short circuit occurs in a secondary battery equipped with an electrode current collector, the short circuit current flows to the short circuit occurrence point S through the current path portion 170 located around the short circuit occurrence point S, or flows to the reaction section 105 including the short circuit occurrence point S.

[0129] Here, the pattern line connecting the peeling portion 160 and the current path portion 170 located around the short circuit occurrence point S may form a fuse section 106 surrounding the short circuit occurrence point S. That is, among the reaction sections 105 divided by the pattern line, the reaction section 105 including the short circuit occurrence point S functions as the fuse section 106.

[0130] The entire current path portion 170 forming the fuse section 106 or the entire current path portion 170 connected to the fuse section 106 is cut off. Only when all current path portions 170 forming the fuse section 106 or connected to the fuse section 106 are cut off can the fuse section 106 be electrically disconnected from the remaining reaction sections 105 and an electrochemical reaction proceed only in the fuse section 106. After all current path portions 170 are cut off, an electrochemical reaction of the electrode active material 103 present in the fuse section 106 is induced, and a short-circuit current flows through the fuse section 106 until the electrochemical reaction is completed.

[0131] 12, a short circuit current flows to the fuse section 106 through two current path parts 170 connected to the fuse section 106 including the short circuit occurrence point S. At this time, the remaining reactive sections 105 do not react to or participate in the short circuit.

[0132] A relatively large short-circuit current flows through all current path parts 170 connected to or in the fuse section 106, and the temperature of the current path parts 170 rises, which may result in the entire current path part 170 being cut off. As the current path part 170 is cut off and the short-circuit current flows only through the fuse section 106, the entire electrode current collector 100 reacts to the short circuit, generating a large amount of heat, and thus preventing accidents such as a battery explosion. In addition, because only the fuse section 106 reacts to the short circuit due to the peeling part 160, the remaining reaction sections 105 that have not reacted to the short circuit can normally function as a battery to a certain extent.

[0133] In addition, when there are multiple current path parts 170 connected to the fuse section 106, current is concentrated in the current path part 170 that is relatively close to the short-circuit occurrence point S, and the conductive material of the conductive material layer 102 located in the current path part 170 melts sequentially or all at once, cutting off the current. At this time, the conductive material of all current path parts 170 connected to the fuse section 106 including the short-circuit occurrence point S may melt, causing the current path part 170 to break and cutting off the current.

[0134] In the case of the electrode current collector 100 shown in Fig. 13, a pattern line connecting the peeling portion 160 and the current path portion 170 is arranged in the longitudinal direction of the base film 101, so that a number of reaction sections 105 may be formed along the width direction of the base film 101. In the case of Fig. 13, the peeling portion 160 and the current path portion 170 may also be formed in the portion where the lead tab 190 is connected.

[0135] In the case of the electrode current collector 100 shown in FIG. 13, all the current path parts 170 connected to the fuse section 106 including the short circuit occurrence point S are cut off to function as a fuse.

[0136] In the case of the electrode current collector 100 shown in Fig. 14, since the pattern lines connecting the peeling portion 160 and the current path portion 170 have a mesh or lattice shape, a plurality of reaction sections 105 may be formed in a mesh or lattice shape. In the case of Fig. 14, the peeling portion 160 and the current path portion 170 may also be formed in the portion where the lead tab 190 is connected.

[0137] 14, the fuse section 106 including the short circuit occurrence point S may be formed to have approximately the same size as the reaction section 105. Although four current path parts 170 are connected to the fuse section 106, all four current path parts 170 may be cut to function as a fuse.

[0138] Compared with FIG. 11 and FIG. 12, in the case of the electrode collector 100 shown in FIG. 13 and FIG. 14, the size of the fuse section 106 including the short circuit occurrence point S is much smaller. Therefore, since the short circuit reaction occurs only in a part divided by the peeling part 160 and the current path part 170, i.e., the small fuse section 106, the length or size of the part of the electrode collector 100 that reacts with the short circuit current can be reduced, and heat is generated only in a part of the electrode collector 100, not in the entire electrode collector 100. In addition, since only the electrode active material 103 in the fuse section 106 reacts during a short circuit, dissipation energy can also be reduced. In addition, the remaining reaction section 105 excluding the fuse section 106 can normally function as an electrode collector to a certain extent.

[0139] In one embodiment of the present invention, the electrode current collector 100 may include a peeling portion 160 and a current path portion 170 that form the fuse section 106 or surround the fuse section 106, and may isolate the fuse section 106 from other reaction sections 105 so that a short-circuit reaction due to a short-circuit current occurs only in the fuse section 106.

[0140] In this manner, in the electrode current collector 100 according to one embodiment of the present invention, by removing only the conductive material forming the conductive material layer 102 on the upper or lower surface of the base film 101, or by removing both the conductive material and the electrode active material 103 at once to form the peeling section 160 and the current path section 170 located between the peeling section 160, the section participating in the short-circuit reaction (fuse section 106) may be isolated or separated from other sections (reaction section 105), thereby preventing the entire electrode current collector 100 from participating in the short-circuit reaction.

[0141] Meanwhile, referring to Figures 11 to 14, a plurality of peeling portions 160 are formed on the same line (pattern line), and at least one current path portion 170 is formed, and the peeling portions 160 and the current path portion 170 located on the same line (pattern line) may be formed to have different lengths or sizes.

[0142] As described above, in the electrode current collector 100 according to one embodiment of the present invention, the conductive material layer 102 and the electrode active material 103 may be applied to the upper or lower surface of the base film 101, and then the conductive material layer 102 and the electrode active material 103 may be partially removed at once using laser patterning to form the peeled portion 160.

[0143] Alternatively, after applying a conductive material layer 102 to the upper or lower surface of the base film 101, a part of the conductive material may be removed by laser patterning, and the surface of the conductive material layer 102 may be coated (applied) with the electrode active material 103 to form the peeling portion 160. In this case, since the surface of the base film 101 is exposed in the peeling portion 160 from which the conductive material has been removed, the electrode active material 103 may be coated (applied) on the surface of the base film 101 located in the peeling portion 160.

[0144] As a result of forming the peeled portion 160 as described above, a current path portion 170 can also be obtained.

[0145] With the electrode active material 103 pressed onto the surface of the conductive material layer 102, the conductive material of the conductive material layer 102 and a part of the electrode active material 103 may be removed all at once by laser patterning, or only the conductive material of the conductive material layer 102 may be removed by laser patterning before the electrode active material 103 is pressed.

[0146] If only the conductive material of the conductive material layer 102 is partially removed by laser patterning without pressing the electrode active material 103 onto the conductive material layer 102, and then the electrode active material 103 is pressed onto the surface of the conductive material layer 102, the electrode active material 103 can be coated onto the surface of the base film 101 located at the peeling portion 160. However, since the resistance of the electrode is high, the current flowing through the electrode active material 103 is extremely small compared to the current flowing through the conductive material layer 102. Therefore, even when the electrode active material 103 is coated on the peeling portion 160, if the conductive material layer 102 is disconnected, the current flow is restricted and the short circuit current is small, thereby reducing heat generation.

[0147] By forming the peeling portion 160 and the current path portion 170 in this manner, a large amount of short-circuit current flows to the current path portion 170 close to the point where a short circuit occurs when a short circuit occurs, and thus it is possible to induce disconnection (disconnection) of the corresponding current path portion 170, thereby ensuring the safety of the battery. However, when a short circuit occurs, the short-circuit current flows not only to the current path portion 170 close to the point where a short circuit occurs, but also to other current path portions 170. However, by inducing a much larger amount of current to flow to the current path portion 170 close to the point where a short circuit occurs, it is possible to minimize the portion of the current collector involved in the short circuit.

[0148] Meanwhile, the inventors of the present application have determined that the size (length) of the current path portion 170 is an important parameter that determines whether the current path portion 170 is cut off in the event of a short circuit. To confirm this, an experiment was conducted to determine under what conditions the current path portion is cut off while changing the size and current of the current path portion 170. The results of the experiment are shown in the following [Table 4].

[0149] (1) Specimen: 12μm PET (base film) + 0.5μm or less aluminum conductive material coated on both sides by sputtering (2) Laser -HG tech's LSF20D -30W integrated laser -Laser wavelength:1,064±1.0nm -Average output power:30±0.8W (3) Experimental conditions: loading level 12.5 mg / cm 2 Standard speed 300mm / s, power 60% (3) Experimental method: Using a power supply, the current was gradually increased until it was insulated and the current value dropped to near 0A. The current value just before it dropped to 0A was measured and recorded.

[0150] [Table 4]

[0151] The experiment in [Table 4] was conducted on a positive electrode current collector 100 having a number of peeling parts 160 and current path parts 170 alternately formed along the width direction of the current collector, as shown in Figures 5 and 6. That is, an experiment was conducted on a lithium secondary battery using such a positive electrode current collector 100.

[0152] In [Table 4], specimen #1 is a case where 10 current path portions 170 with an individual length of 0.5 mm are formed, specimen #2 is a case where 5 current path portions 170 with an individual length of 1 mm are formed, specimen #3 is a case where 4 current path portions 170 with an individual length of 1.25 mm are formed, specimen #4 is a case where 2 current path portions 170 with an individual length of 2.5 mm are formed, and specimen #5 is a case where 1 current path portion 170 with a length of 5.0 mm is formed.

[0153] Here, the length of the current path portion 170 is the length measured along the direction of the pattern line formed by the peeling portion 160 and the current path portion 170, and the total length of the current path portion 170 formed in each specimen was 5 mm.

[0154] [Table 4] shows the current (A) value increased and the current value at which the current path portion 170 is cut off is recorded. The experiment was repeated a total of six times for each specimen.

[0155] As a result of the experiment, it was confirmed that if the length of the current path portion 170 is 1 mm or more, the current path portion can be cut even when the current value is small.

[0156] As shown in Table 4, if the current path portion 170 is divided into smaller pieces, it can be seen that the current value that performs the fuse function is larger. Since it is advantageous for the current path portion 170 to be cut with a small current, it is preferable to make the size of the current path portion 170 1 mm or more, as in specimen #2.

[0157] Therefore, when the electrode current collector 100 according to one embodiment of the present invention is a positive electrode current collector, it is preferable that one or a plurality of (at least one or more) current path portions 170 having a length of 1 mm or more are formed.

[0158] In the electrode current collector 100 according to one embodiment of the present invention described above, the area where the electrode active material 103 is applied is divided into a number of reaction sections 105 by the peeling portion 160 and the current path portion 170, and each of the reaction sections 105 can function as an electrical fuse when short-circuited.

[0159] Therefore, the electrode current collector 100 according to an embodiment of the present invention can ensure the safety of a battery by allowing a short circuit reaction to occur only in a reaction section including the short circuit occurrence point, or isolating the short circuit from other reaction sections, even if a short circuit occurs. In particular, when the electrode current collector 100 is a positive electrode current collector and is used in a large-capacity lithium secondary battery, accidents such as a fire or explosion of the battery due to a short circuit can be prevented in advance.

[0160] As described above, in one embodiment of the present invention, specific details such as specific components and the like are described using limited embodiments and drawings, but this is merely provided to help a more general understanding of the present invention, and the present invention is not limited to the above-mentioned embodiments, and a person having ordinary knowledge in the field to which the present invention belongs can make various modifications and variations from such descriptions. Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the scope of the claims, as well as the following claims, are within the scope of the idea of ​​the present invention.

Claims

1. A base film; a conductive layer including a conductive material formed on at least one of an upper surface and a lower surface of the base film; An electrode active material formed on the surface of the conductive material layer, The conductive material layer is A current collector for an electrode comprising: a peeling portion in which the conductive material is not present or is formed by removing the conductive material so that the base film is exposed; and a current path portion located between the peeling portions, in which the conductive material is present on a surface of the base film.

2. 2. The current collector for an electrode according to claim 1, wherein the peeling portion is formed in a state in which the conductive material is not present or is removed so that at least one of an upper surface and a lower surface of the base film is exposed, or the peeling portion includes the electrode active material formed on at least one of an upper surface and a lower surface of the base film exposed by removing or not presenting the conductive material.

3. The electrode current collector according to claim 2 , wherein the current path portion is formed in a state in which the conductive material is present on at least one of an upper surface and a lower surface of the base film.

4. The electrode current collector according to claim 3 , wherein the current path portion includes the electrode active material formed on a surface of the conductive material present on at least one of an upper surface and a lower surface of the base film.

5. 3. The electrode current collector according to claim 2, wherein the current path portion is located between the peeling portions along an arrangement direction of the peeling portions, or is located between the peeling portions along a pattern direction formed by connecting the peeling portions and the current path portion.

6. 5. The current collector for an electrode according to claim 4, wherein an area of ​​the conductive material layer or an area of ​​the electrode active material is divided into a plurality of reaction sections by pattern lines formed by connecting the peeling portion and the current path portion.

7. The electrode current collector according to claim 6 , wherein when a short circuit occurs in a secondary battery including the electrode current collector, a short circuit current flows to the point where the short circuit occurs through the current path portion located around the point where the short circuit occurs.

8. Among the reaction sections, a reaction section in which the short circuit occurrence point is located becomes a fuse section that functions as an electrical fuse, The current collector for an electrode according to claim 7 , wherein the entire current path portion forming the fuse section or the entire current path portion connected to the fuse section is cut, and an electrochemical reaction of the electrode active material present in the fuse section proceeds in a state in which all of the current path portions are cut.

9. 8. The current collector for an electrode according to claim 7, wherein all of the current path portions forming or connected to the fuse section are cut off, and an electrochemical reaction of the electrode active material present in the fuse section is induced in a state in which the fuse section is electrically disconnected, and a short-circuit current flows through the fuse section until the electrochemical reaction is completed.

10. The current collector for an electrode according to claim 8 , wherein the peeling portion and the current path portion forming the fuse section or surrounding the fuse section isolate the fuse section from the reaction section so that a short-circuit reaction due to a short-circuit current occurs only in the fuse section, or isolate or separate the fuse section participating in a short-circuit reaction from the reaction section.

11. The peeling portion is formed on the same line among the pattern lines formed by connecting the peeling portion and the current path portion, At least one of the current path portions is formed on the same line, The current collector for an electrode according to claim 10 , wherein the peeling portion and the current path portion located on the same line are formed to have different lengths or sizes.

12. The electrode current collector according to claim 6 , wherein the base film is made of a transparent material.

13. The current collector for an electrode according to claim 12 , wherein the peeling portion and the current path portion are symmetrically formed on the upper and lower surfaces of the base film.

14. The current collector for an electrode according to claim 12 , wherein the peeling portion and the current path portion are symmetrically formed on the upper and lower surfaces of the base film by laser patterning.

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