Electrode for secondary battery and lithium secondary battery including same

Abstract

The electrode for a secondary battery according to an embodiment of the present disclosure includes: an electrode current collector; electrode mixture layers on both surfaces of the electrode current collector; and insulating layers on both surfaces of the electrode current collector, wherein the electrode for a secondary battery has an α value of 0 to 1 according to Equation 1 below. [Equation 1] In Equation 1 above, α is a foil curl parameter, TAis the thickness value in micrometers (μm) of the insulating layer on one surface of the current collector, TB is the thickness value in micrometers (μm) of the insulating layer on the other surface of the current collector, and W is the width value in millimeters (mm) of the insulating layer. According to an embodiment of the present disclosure, it is possible to alleviate problems caused by foil curl in an electrode for a secondary battery.

Description

Electrode for secondary battery and lithium secondary battery including same

[0001] The present disclosure relates to an electrode for a secondary battery and a lithium secondary battery including the same.

[0002] Recently, much research has been conducted on electric vehicles (EVs) that can replace fossil fuel-powered vehicles such as gasoline and diesel vehicles, which are one of the main causes of air pollution. Lithium secondary batteries with high discharge voltage and output stability are mainly used as the power source for these EVs.

[0003] During the operation of the lithium secondary battery, safety issues may arise due to short circuits within the battery. These short circuits can occur due to direct contact between the battery's electrodes, and if the short circuit persists, it can cause a fire within the battery.

[0004] Accordingly, there is a need for the development of technologies that can prevent problems such as short circuits and resulting fires within secondary batteries.

[0005] According to one aspect of the present disclosure, it is possible to prevent the foil curl level from becoming worse during the manufacture of an electrode for a secondary battery.

[0006] According to another aspect of the present disclosure, it is possible to suppress a short circuit phenomenon from occurring inside a secondary battery.

[0007] According to another aspect of the present disclosure, it is possible to prevent a decrease in yield in a secondary battery production process.

[0008] The secondary battery electrode of the present disclosure and the lithium secondary battery comprising the same can be widely applied in green technology fields such as electric vehicles, battery charging stations, and other battery-based solar and wind power generation. Furthermore, the secondary battery electrode of the present disclosure and the lithium secondary battery comprising the same can be used in eco-friendly electric vehicles, hybrid vehicles, and the like, which aim to prevent climate change by suppressing air pollution and greenhouse gas emissions.

[0009] An electrode for a secondary battery according to one embodiment of the present disclosure includes: an electrode current collector; an electrode mixture layer on both sides of the electrode current collector; and an insulating layer on both sides of the electrode current collector, wherein the electrode for a secondary battery has an α value of 0 to 1 according to the following equation 1.

[0010] [Formula 1]

[0011]

[0012] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

[0013] In some embodiments, the electrode current collector may include a bare portion on which an electrode composite layer is not disposed on a surface.

[0014] In some implementations, the insulating layer may be disposed on the non-conductive portion.

[0015] In some implementations, the insulating layer may be positioned to cover a portion of the electrode composite layer from a portion of the non-conductive portion.

[0016] In some embodiments, the electrode for the secondary battery may have an α value of 0 to 0.9 according to Equation 1.

[0017] In some embodiments, the electrode for the secondary battery may have an α value greater than 0 according to Equation 1.

[0018] In some embodiments, the secondary battery electrode is T according to the above formula 1 A Value and T B The values ​​may be different.

[0019] In some embodiments, the secondary battery electrode has |T according to the above formula 1. A - T B | The value can be greater than 0 and less than or equal to 2.

[0020] In some embodiments, the secondary battery electrode is T according to the above formula 1 A The value can be between 5 and 15.

[0021] In some embodiments, the secondary battery electrode is T according to the above formula 1 B The value can be between 5 and 15.

[0022] In some embodiments, the electrode for the secondary battery may have a W value of 3 to 10 according to the above formula 1.

[0023] In some implementations, the insulating layer may comprise an insulating polymer.

[0024] In some embodiments, the insulating polymer may include at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polyvinylacetate (PVA), polyethylene oxide (PEO), cellulose acetate (CA), cellulose acetate butyrate (CAB), and copolymers thereof.

[0025] In some embodiments, the insulating polymer may comprise a graft copolymer of a first polymer and a second polymer. The first polymer may be polyimide (PI) or polyamideimide (PAI), and the second polymer may be styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR).

[0026] A lithium secondary battery according to one embodiment of the present disclosure includes an electrode for a secondary battery according to any one of the above-described embodiments.

[0027] According to one embodiment of the present disclosure, problems caused by foil curl in a secondary battery electrode can be alleviated.

[0028] According to another embodiment of the present disclosure, the safety of a secondary battery can be improved.

[0029] According to another embodiment of the present disclosure, the fairness of the production process of a secondary battery can be improved.

[0030] Figure 1 is a cross-sectional view conceptually illustrating an electrode for a secondary battery according to one embodiment.

[0031] Figure 2 is a perspective view conceptually illustrating an electrode for a secondary battery according to an embodiment.

[0032] Figure 3 is a cross-sectional view conceptually illustrating an electrode for a secondary battery according to another embodiment.

[0033] Figure 4 is a cross-sectional view conceptually illustrating an electrode for a secondary battery according to another embodiment.

[0034] Figure 5 is a top view conceptually illustrating an electrode for a secondary battery according to another embodiment.

[0035] Figure 6 is a drawing showing the results of confirming the bending level of a secondary battery electrode according to a reference example.

[0036] Figure 7 is a drawing showing the results of confirming the bending level of the electrode for a secondary battery according to Example 1.

[0037] Figure 8 is a drawing showing the results of confirming the level of bending in the electrode for a secondary battery according to Example 2.

[0038] Figure 9 is a drawing showing the results of checking the level of bending in the electrode for a secondary battery according to Comparative Example 1.

[0039] Hereinafter, the technology disclosed in this specification and its implementation examples will be described in detail with reference to the attached drawings. However, the embodiments of the technology may be modified in various other forms, and the scope is not limited to the implementation examples described below. Furthermore, the technology disclosed in this specification may be applied not only by being limited to the configurations of the implementation examples described below, but also by selectively combining all or some of the implementation examples to enable various modifications.

[0040] As described above, there is a need for technology that can prevent short circuits within lithium secondary batteries. According to one embodiment, short circuits between electrodes can be prevented by coating the current collector of the electrode with an insulating layer. For example, coating the positive electrode current collector with an insulating layer can prevent short circuits even when in direct contact with the negative electrode.

[0041] Meanwhile, in the coating process of forming an insulating layer on both sides of the electrode current collector, there may be variations in the thickness of the insulating layer formed on both sides of the electrode current collector. In particular, if the insulating layer contains a polymer material such as polyimide (PI) or polyamideimide (PAI) with a relatively high coefficient of thermal expansion as an insulating material, the variation in the thickness of the insulating layer formed on both sides may aggravate the foil curl phenomenon, which causes the electrode current collector to bend.

[0042] This foil curl phenomenon is not found during the coating process or winding process during electrode manufacturing, but can be found to be aggravated during the vacuum drying process when the insulating layer is heated / cooled. If the foil curl phenomenon is aggravated, the product quality and yield may be reduced during the subsequent assembly process. In particular, the unit cell folding phenomenon may occur during the stacking process, resulting in double sheets, and wrinkles may form on the electrode tab portion during the welding process.

[0043] According to one embodiment of the present disclosure, the aforementioned problems can be alleviated by preventing the foil curl level from worsening during the electrode manufacturing process. Hereinafter, embodiments of the present disclosure will be described in detail with reference to FIGS. 1 to 9.

[0044] Electrode for secondary battery

[0045] An electrode (100) for a secondary battery according to one embodiment includes an electrode current collector (10); an electrode mixture layer (20) on both sides of the electrode current collector; and an insulating layer (30) on both sides of the electrode current collector, wherein the electrode for a secondary battery has an α value of 0 to 1 according to the following equation 1.

[0046] [Formula 1]

[0047]

[0048] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

[0049] FIG. 1 and FIG. 2 are a cross-sectional view and a perspective view, respectively, conceptually illustrating an electrode for a secondary battery according to one embodiment, FIG. 3 and FIG. 4 are cross-sectional views conceptually illustrating an electrode for a secondary battery according to another embodiment, and FIG. 5 is a top view conceptually illustrating an electrode of a secondary battery according to another embodiment.

[0050] Referring to FIGS. 1 to 5, the secondary battery electrode (100) may include an electrode current collector (10), an electrode mixture layer (20), and an insulating layer (30). The electrode mixture layer and the insulating layer on one surface of the electrode current collector (10) may be a first electrode mixture layer (21) and a first insulating layer (31), respectively. The electrode mixture layer and the insulating layer on the other surface of the electrode current collector (10) may be a second electrode mixture layer (22) and a second insulating layer (32), respectively.

[0051] In addition, referring to FIGS. 1 to 5, the width (W) of the insulating layer may be a straight line length from one end of the insulating layer to the other end based on the width direction of the electrode mixture layer (20). Specifically, the width (W) of the insulating layer may be a straight line length from the point where the insulating layer (30) contacts the electrode mixture layer (20) to one end of the insulating layer (30) on the non-coated portion based on the width direction of the electrode mixture layer.

[0052] In addition, when there is an overlap area (A) to be described later, the width (W) of the insulating layer may be excluding the overlap area (A). Specifically, when there is an overlap area (A) to be described later, the width (W) of the insulating layer may be a straight line length from a point on the surface of the electrode current collector (10) where the insulating layer (30) comes into contact with the electrode mixture layer (20) to one end of the insulating layer (30) on the non-coated portion, based on the width direction of the electrode mixture layer (see FIGS. 3 to 5).

[0053] The widths (W) of the first insulating layer (31) and the second insulating layer (32) may be the same or different from each other. When the widths (W) of the first insulating layer (31) and the second insulating layer (32) are different from each other, W in the above formula 1 may be based on the width (W) of either the first insulating layer (31) or the second insulating layer (32). Specifically, W in the above formula 1 may be the longer or shorter of the widths (W) of the first insulating layer (31) and the second insulating layer (32).

[0054] The width direction of the electrode mixture layer (20) may be a direction perpendicular to the boundary line of the electrode current collector (20) and the electrode mixture layer (20), or a direction perpendicular to the boundary line of the electrode mixture layer (20) and the insulating layer (30). In addition, when there is a step between the electrode current collector (10) and the insulating layer (30), the step may be formed parallel (parallel) to the width direction.

[0055] For example, the width direction of the electrode composite layer (20) may be perpendicular to the protruding direction of the tab in the case of a winding type electrode assembly, and may be parallel (or in parallel) to the protruding direction of the tab in the case of a stacking type or zigzag folding type.

[0056] The components of the electrode current collector (10) are not particularly limited. For example, the electrode current collector (10) may be a plate or foil made of one or more of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), and alloys thereof. The thickness of the electrode current collector (10) is not particularly limited. For example, the thickness of the electrode current collector (10) may be 0.1 μm to 50 μm.

[0057] When the secondary battery electrode (100) is a negative electrode, in some embodiments, the electrode current collector (10) may be copper foil (Cu-foil). When the secondary battery electrode (100) is a positive electrode, in some embodiments, the electrode current collector (10) may be aluminum foil (Al-foil).

[0058] The above electrode current collector (10) may include a non-coated portion on which an electrode mixture layer (20) is not disposed on the surface. Specifically, the non-coated portion may be a region of the electrode current collector (10) on which a first electrode mixture layer (21) is not disposed on one surface and a second electrode mixture layer (22) is not disposed on the other surface.

[0059] In some implementations, the insulating layer (30) may be disposed on the non-conductive portion. Specifically, in the secondary battery electrode (100), the first insulating layer (31) and the second insulating layer (32) may be disposed on the non-conductive portion (see FIGS. 1 and 2).

[0060] In some embodiments, the insulating layer (30) may be arranged to cover a portion of the electrode mixture layer (20) from a portion of the non-coated portion. Specifically, in the secondary battery electrode (100), the first insulating layer (31) may be arranged to cover a portion of the first electrode mixture layer (21) from a portion of the non-coated portion, and the second insulating layer (32) may be arranged to cover a portion of the second electrode mixture layer (22) from a portion of the non-coated portion (see FIGS. 3 to 5 ). At this time, the thickness of the insulating layer (30) may be less than or equal to the thickness of the electrode mixture layer (20) (see FIGS. 3 and 4 ).

[0061] In this specification, the region where the insulating layer (30) covers a portion of the electrode mixture layer (20) in the secondary battery electrode (100) may be an overlap region (A). The overlap region (A) is a region where the insulating layer (30) is formed to cover a portion of the electrode mixture layer (20) so that the insulating layer (30) and a portion of the electrode mixture layer (20) overlap each other, and as the insulating layer (30) covers a portion of the electrode mixture layer (20), the overlap region (A) can prevent the exposure of the electrode current collector (10).

[0062] Specifically, in the secondary battery electrode (100), the area where the first insulating layer (31) covers a part of the first electrode mixture layer (21) may be a first overlap area (A1), and the area where the second insulating layer (32) covers a part of the second electrode mixture layer (22) may be a second overlap area (A2) (see FIGS. 3 and 4).

[0063] In some embodiments, the insulating layer (30) on one surface of the electrode current collector (10) may be disposed on the non-coated portion, and the insulating layer (30) on the other surface of the electrode current collector (10) may be disposed to cover a portion of the electrode mixture layer (20) from a portion of the non-coated portion. Specifically, in the secondary battery electrode (100), one of the first insulating layer (31) and the second insulating layer (32) may be disposed to cover a portion of one of the first electrode mixture layer (21) and the second electrode mixture layer (22) from a portion of the non-coated portion, and the other of the first insulating layer (31) and the second insulating layer (32) may be disposed to cover a portion of the other of the first electrode mixture layer (21) and the second electrode mixture layer (22) from a portion of the non-coated portion (not shown).

[0064] In some implementations, the length (L) of the overlap area (A) where the insulating layer (30) covers a portion of the electrode composite layer (20) A ) and the length (L) of the electrode mixture layer (20) T ) can be from 1:100 to 1:100,000. Specifically, the length (L) of the overlap area (A)A ) and the length (L) of the electrode mixture layer (20) T ) may be 1:500 to 1:1,500, or 1:800 to 1:1,200. When the length ratio of the overlap area (A) to the electrode composite layer (20) is within the above-described range, exposure of the electrode current collector (10) can be prevented while also preventing a decrease in the capacity of the electrode.

[0065] In some implementations, the length (L) of the overlap area (A) A ) may be greater than 0 mm and less than 5 mm. Specifically, the length (L) of the overlap area (A) A ) may be greater than 0 mm and less than 2 mm. The length (L) of the above overlap area (A) A ) is within the above-described range, the overlap area (A) can be formed with excellent fairness.

[0066] The length (L) of the above electrode mixture layer (20) T ) may be a straight line length from one end to the other end based on the width direction of the electrode composite layer (20). In addition, the length (L) of the overlap area (A) A ) may be a straight line length from the point where the insulating layer (30) comes into contact with the electrode mixture layer (20) to one end of the electrode mixture layer (20) covered by the insulating layer, based on the width direction of the electrode mixture layer.

[0067] The secondary battery electrode (100) may have a foil curl parameter (α) value of 1 or less according to the above formula 1. The foil curl parameter is a parameter designed by considering the thickness, width, etc. of the insulating layer (30) formed on both sides of the electrode current collector (10), considering that it is impossible to form an insulating layer (30) having an absolute numerically completely identical thickness on both sides of the electrode current collector (10) in terms of the process, and when the foil curl parameter (a) value is 1 or less, the warpage level can be low while the processability can be excellent. Therefore, in the above formula 1, T A and T BThe values ​​can be different, and the value of α can be different from 0.

[0068] In some embodiments, the secondary battery electrode (100) may have an α value according to Equation 1 of greater than 0, greater than or equal to 0.01, or greater than or equal to 0.1. Specifically, the secondary battery electrode (100) may have an α value according to Equation 1 of greater than or equal to 0.4, or greater than or equal to 0.45, and may be less than or equal to 0.9, less than or equal to 0.7, or less than or equal to 0.5.

[0069] When the secondary battery electrode (100) is designed so that the foil curl parameter (α) value according to the above equation 1 satisfies the above-described range, the foil curl phenomenon of the electrode can be prevented from being aggravated during the secondary battery manufacturing process. Accordingly, the yield and processability in the assembly process during secondary battery manufacturing can be improved.

[0070] In some implementations, the thickness of the insulating layer (30) may be 1 μm to 200 μm. Specifically, the thickness (T) of the first insulating layer (31) A ) and the thickness (T) of the second insulating layer (32) B ) may be 1 μm to 200 μm, respectively. A thinner thickness of the insulating layer may be advantageous for material savings, but if the thickness is excessively thin, it may cause a short circuit of the electrode. The appropriate thickness of the insulating layer (30) may vary depending on the material included in the insulating layer.

[0071] In some embodiments, the secondary battery electrode (100) is T according to the above formula 1. A The value may be 5 to 15. That is, the thickness of the first insulating layer (31) of the secondary battery electrode (100) may be 5 μm to 15 μm. Specifically, the thickness of the first insulating layer (31) of the secondary battery electrode (100) may be 6 μm or more or 8 μm or more, and 13 μm or less, 10 μm or less, or 9 μm or less.

[0072] In some embodiments, the secondary battery electrode (100) is T according to the above formula 1. B The value may be 5 to 15. That is, the thickness of the second insulating layer (32) of the secondary battery electrode (100) may be 5 μm to 15 μm. Specifically, the thickness of the second insulating layer (32) of the secondary battery electrode (100) may be 7 μm or more or 9 μm or more, and 14 μm or less, 12 μm or less, or 10 μm or less.

[0073] The above T A and T B- If the value is less than 5 or greater than 15, it may be difficult to alleviate the problem caused by foil curl in the secondary battery electrode (100).

[0074] In some implementations, the thickness of the insulating layer (30) may be uniform (see FIGS. 1 and 2) or non-uniform (see FIGS. 3 and 4). When the thickness of the insulating layer (30) is non-uniform, the thickness of the insulating layer (30) for calculating the foil curl parameter (α) value according to Equation 1 may be the thickness from the surface of the electrode current collector (10) to the surface located furthest in the thickness direction of the insulating layer (30) (i.e., the thickness of the thickest part of the insulating layer (30). That is, in Equation 1, T A The value may be a value measured for the thickness of the thickest part of the first insulating layer (31), and T in the above equation 2 B The value may be a value measured for the thickness of the thickest part of the second insulating layer (32).

[0075] In some embodiments, the secondary battery electrode (100) has |T according to the above formula 1. A - T B| The value may be 2 or less. That is, the secondary battery electrode (100) may have a thickness deviation of 2 μm or less between the first insulating layer (31) and the second insulating layer (32). Specifically, the secondary battery electrode (100) may have a thickness deviation of more than 0 μm, 0.1 μm or more, or 1 μm or more, and may be 1.8 μm or less, 1.6 μm or less, or 1.2 μm or less.

[0076] Above |T A - T B | If the value exceeds 2, the foil curl phenomenon may be aggravated in the secondary battery electrode (100) due to the thickness deviation of the insulating layer (30) placed on both sides of the electrode collector (10).

[0077] In some implementations, the widths of the insulating layers (30) disposed on both sides of the electrode current collector (10) may be substantially the same. Here, substantially the same may specifically mean a degree of being the same to the extent that the difference cannot be recognized by measuring equipment, and for example, may mean that the difference in the widths of the insulating layers (30) disposed on both sides of the electrode current collector (10) is within 1%, within 0.5%, or within 0.1% based on the width length of the longer insulating layer.

[0078] In some implementations, the secondary battery electrode (100) may have a W value of 3 to 10 according to the above formula 1. That is, the secondary battery electrode (100) may have a first insulating layer (31) and a second insulating layer (32) each having a width of 3 mm to 10 mm. Specifically, the secondary battery electrode (100) may have a first insulating layer (31) and a second insulating layer (32) each having a width of 4 mm or more, and may be 9 mm or less, 7 mm or less, or 5 mm or less.

[0079] In order to prevent an internal short circuit from occurring in the secondary battery electrode (100), the insulating layer (30) may be formed to have the same width as the electrode current collector (10) and the electrode mixture layer (20) (see FIGS. 2 and 5). Therefore, when the width of the insulating layer (30) is less than 3 mm, the widths of the electrode current collector (10) and the electrode mixture layer (20) are also less than 3 mm, making it difficult to secure the capacity of the electrode.

[0080] In addition, as the width of the insulating layer (30) increases, the thickness deviation of the insulating layer (30) disposed on both sides of the electrode current collector (10) may be increased, thereby increasing the possibility of occurrence of a foil curl phenomenon in the secondary battery electrode (100). Therefore, when the width of the insulating layer (30) exceeds 10 mm, the occurrence of a foil curl phenomenon in the secondary battery electrode (100) may be aggravated.

[0081] In some embodiments, the insulating layer (30) may include an insulating polymer and, if necessary, may further include a ceramic material. For example, the first insulating layer (31) and the second insulating layer (32) may each include at least one of an insulating polymer and a ceramic material.

[0082] The insulating polymer is not particularly limited as long as it is a polymer having insulating properties and can prevent short circuits between electrodes. For example, the insulating polymer may include at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polyvinylacetate (PVA), polyethylene oxide (PEO), cellulose acetate (CA), cellulose acetate butyrate (CAB), and copolymers thereof.

[0083] The above insulating polymer may include a copolymer, and the copolymer may include at least one selected from the group consisting of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer.

[0084] In some embodiments, the insulating polymer may include at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), styrene-butadiene rubber (SBR), hydrogenated nitrile-butadiene rubber (HNBR), and copolymers thereof.

[0085] In some embodiments, the insulating polymer may include a copolymer of polyimide (PI) or polyamideimide (PAI); and styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR). More specifically, the insulating polymer may include a graft copolymer of polyimide (PI) or polyamideimide (PAI); and styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR).

[0086] In the above graft copolymer, polyimide (PI) or polyamideimide (PAI) may be the first polymer, and styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR) may be the second polymer. That is, the graft copolymer may be a copolymer obtained by grafting the above-described first polymer and the second polymer.

[0087] The content of the insulating polymer that can be included in the insulating layer (30) is not particularly limited. For example, the content of the insulating polymer included in the insulating layer (30) may be 1 to 99 wt%.

[0088] The above ceramic material is not particularly limited as long as it is a ceramic material having insulating properties and can prevent short circuits between electrodes. For example, the ceramic material may include at least one selected from the group consisting of alumina (Al2O3), alumina hydrate (AlOOH), aluminum nitride (AlN), silicon carbide (SiC), and magnesium oxide (MgO).

[0089] The content of the ceramic material that can be included in the above insulating layer (30) is not particularly limited. For example, the content of the ceramic material included in the above insulating layer (30) may be 1 to 99 wt%.

[0090] The electrode mixture layer (20) may include an electrode active material. When the secondary battery electrode is a negative electrode, the electrode mixture layer (20) may include a negative electrode active material. When the secondary battery electrode is a positive electrode, the electrode mixture layer (20) may include a positive electrode active material.

[0091] The above negative electrode active material is not particularly limited. For example, the negative electrode active material may be at least one selected from the group consisting of carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers; lithium metal; lithium alloys; silicon-containing materials, and tin-containing materials.

[0092] The above crystalline carbon may be, for example, graphitic carbon such as natural graphite, artificial graphite, graphitized coke, graphitized mesocarbon microbead (MCMB), graphitized mesophase pitch-based carbon fiber (MPCF), etc.

[0093] Examples of the above amorphous carbon may include hard carbon, soft carbon, coke, mesocarbon microbead (MCMB), or mesophase pitch-based carbon fiber (MPCF).

[0094] The lithium metal may be pure lithium metal or lithium metal with a protective layer formed thereon for suppressing dendrite growth, etc. In one embodiment, a lithium metal-containing layer deposited or coated on an anode current collector may be used as the anode active material layer. In one embodiment, a lithium thin film layer may be used as the anode active material layer.

[0095] Elements included in the above lithium alloy may be, for example, aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium or indium.

[0096] The silicon-containing material is not particularly limited as long as it contains silicon, and may be an active material capable of being alloyed with lithium (Li). For example, the silicon-containing material may be silicon (Si), silicon oxide (SiOx; 0 <x<2), 금속 도핑된 실리콘 산화물(SiOx; 0<x<2), 탄소 코팅된 실리콘 산화물(SiOx; 0<x<2), 실리콘-탄소 복합체(Si-C) 및 실리콘 합금으로 이루어진 군으로부터 선택된 1종 이상일 수 있다.

[0097] The above positive electrode active material is not particularly limited. For example, the positive electrode active material may include a lithium-nickel metal oxide. The lithium-nickel metal oxide may further include at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0098] In some embodiments, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or crystal structure represented by the following chemical formula 1.

[0099] [Chemical Formula 1]

[0100] Li x Ni a M b O 2+z

[0101] In the above chemical formula 1, 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b≤0.4, -0.5≤z≤0.1 may be satisfied. As described above, M may include Co, Mn, and / or Al.

[0102] The chemical structure represented by the above chemical formula 1 represents the bonding relationship included in the layered structure or crystal structure of the positive electrode active material and does not exclude other additional elements. For example, M includes Co and / or Mn, and Co and / or Mn can serve as the main active element of the positive electrode active material together with Ni. The above chemical formula 1 is provided to express the bonding relationship of the above main active elements and should be understood as a formula encompassing the introduction and substitution of additional elements.

[0103] In some embodiments, auxiliary elements may be further included in addition to the main active element to enhance the chemical stability of the positive electrode active material or the layered / crystal structure. The auxiliary elements may be incorporated into the layered / crystal structure to form bonds, and in this case, it should be understood that they are also included within the chemical structure range represented by Chemical Formula 1.

[0104] The auxiliary element may include, for example, at least one of Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr. The auxiliary element may also function as an auxiliary active element that contributes to the capacity / output activity of the positive electrode active material together with Co or Mn, such as Al.

[0105] For example, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or crystal structure represented by the following chemical formula 1-1.

[0106] [Chemical Formula 1-1]

[0107] Li x Ni a M1 b1 M2 b2 O 2+z

[0108] In Chemical Formula 1-1, M1 may include Co, Mn, and / or Al. M2 may include the auxiliary elements described above. In Chemical Formula 1-1, 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b1+b2≤0.4, -0.5≤z≤0.1 may be satisfied.

[0109] The above-described positive electrode active material may further include a coating element or doping element. For example, elements substantially identical to or similar to the above-described auxiliary elements may be used as the coating element or doping element. For example, the above-described elements may be used singly or in combination of two or more.

[0110] The above coating element or doping element may be present on the surface of the lithium-nickel metal oxide particle, or may penetrate through the surface of the lithium-nickel metal composite oxide particle and be included in the bonding structure represented by the above chemical formula 1 or chemical formula 1-1.

[0111] The above positive electrode active material may include a nickel-cobalt-manganese (NCM) lithium oxide. In this case, an NCM lithium oxide with an increased nickel content may be used.

[0112] The content of Ni (e.g., the mole fraction of nickel among the total moles of nickel, cobalt, and manganese) in the NCM-based lithium oxide may be 0.6 or more, 0.7 or more, or 0.8 or more. In some embodiments, the content of Ni may be 0.8 to 0.95, 0.82 to 0.95, 0.83 to 0.95, 0.84 to 0.95, 0.85 to 0.95, or 0.88 to 0.95.

[0113] In some embodiments, the positive electrode active material may include a lithium cobalt oxide-based active material, a lithium manganese oxide-based active material, a lithium nickel oxide-based active material, or a lithium iron phosphate (LFP)-based active material (e.g., LiFePO4).

[0114] In some embodiments, the positive electrode active material may include a Mn-rich active material, a Li-rich layered oxide (LLO) / over lithiated oxide (OLO) active material, or a Co-less active material having a chemical structure or crystal structure represented by chemical formula 2.

[0115] [Chemical Formula 2]

[0116] p[Li2MnO3]·(1-p)[Li q JO2]

[0117] In chemical formula 2, 0 <p<1이고, 0.9≤q≤1.2이며, J는 Mn, Ni, Co, Fe, Cr, V, Cu, Zn, Ti, Al, Mg 및 B 중 적어도 하나의 원소를 포함할 수 있다.

[0118] The above electrode mixture layer (20) may further include a binder. The binder is not particularly limited. For example, the positive electrode mixture layer may include one or two or more types of binders, such as polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0119] In addition, the negative electrode composite layer may include any one selected from among a rubber binder such as styrene-butadiene rubber (SBR), fluorine-based rubber, ethylene propylene rubber, butadiene rubber, isoprene rubber, and silane-based rubber; a cellulose-based binder such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose, methylcellulose, or an alkali metal salt thereof; and a combination thereof.

[0120] The electrode mixture layer (20) may further include a conductive material. The conductive material is not particularly limited. For example, the conductive material may include one or more types of graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, and carbon nanotubes (CNT); metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives.

[0121] The secondary battery electrode (100) according to the above-described implementation examples can be manufactured by the manufacturing method described below.

[0122] Method for manufacturing electrodes for secondary batteries

[0123] A method for manufacturing an electrode (100) for a secondary battery according to one embodiment includes a step of forming an electrode mixture layer (20) and an insulating layer (30) on both sides of an electrode current collector (10), and the electrode for a secondary battery has an α value of 1 or less according to the following equation 1.

[0124] [Formula 1]

[0125]

[0126] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

[0127] Detailed descriptions of the electrode current collector (10), electrode composite layer (20), insulating layer (30), etc. overlap with the above-described contents, so descriptions are omitted.

[0128] In some implementations, the step of forming the electrode mixture layer (20) and the insulating layer (30) may be performed by first forming the electrode mixture layer (20) on both sides of the electrode current collector (10) and then forming the insulating layer (30).

[0129] In some embodiments, the electrode mixture layer (20) may be formed on both surfaces of the electrode current collector (10) by applying a slurry containing an electrode active material to both surfaces of the electrode current collector (10) and drying the electrode slurry at 80 to 120° C. The method for applying the electrode slurry is not particularly limited. For example, the electrode slurry may be applied to the surface of the electrode current collector (10) by a method such as bar coating, casting, or spraying.

[0130] In some embodiments, the electrode slurry may further include a solvent. The solvent is not particularly limited. For example, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, etc. may be used as the solvent. The amount of the solvent used is not particularly limited as long as it dissolves or disperses the components in consideration of the coating thickness of the slurry, manufacturing yield, etc., and has a viscosity that can exhibit excellent thickness uniformity when applied to a current collector.

[0131] In some embodiments, the insulating layer (30) may be formed on both sides of the electrode current collector (10) by applying a composition (insulating liquid) containing an insulating material to both sides of the electrode current collector (10) and drying the composition at 80 to 120° C. At this time, the insulating layer (30) may be formed such that the thickness, width, etc., of the foil curl parameter (α) according to Equation 1, satisfy the above-described range.

[0132] In some implementations, the insulating layer (30) may be formed in a structure arranged on the non-conductive portion of the electrode current collector (10) (see FIG. 1), or may be formed in a structure arranged to cover a portion of the electrode mixture layer from a portion of the non-conductive portion (see FIG. 2).

[0133] In some embodiments, the method for manufacturing the secondary battery electrode (100) may further include a step of vacuum drying the secondary battery electrode manufactured by the method according to any one of the above-described embodiments.

[0134] The vacuum drying conditions of the secondary battery electrode (100) are not particularly limited. For example, the vacuum drying of the secondary battery electrode (100) may be performed at a temperature of 80°C to 200°C for 1 to 24 hours.

[0135] lithium secondary battery

[0136] A lithium secondary battery according to one embodiment includes an electrode (100) for a secondary battery according to any one of the above-described embodiments. Specifically, the lithium secondary battery may include a unit cell including an electrode (100) for a secondary battery according to any one of the above-described embodiments as a negative electrode or a positive electrode.

[0137] In some embodiments, the unit cell may further include a separator between the positive and negative electrodes. The separator is not particularly limited. For example, the separator may include a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer. In addition, the separator may include a nonwoven fabric formed of high-melting-point glass fibers, polyethylene terephthalate fibers, or the like.

[0138] According to exemplary embodiments, two or more unit cells including the positive electrode, negative electrode, and separator may be repeatedly arranged to form an electrode assembly. In some embodiments, the electrode assembly may be of a winding type, a stacking type, a z-folding type, or a stack-folding type.

[0139] In some embodiments, the lithium secondary battery can be manufactured by housing the above-described unit cell in a pouch, which is a battery case, and then injecting an electrolyte.

[0140] The electrolyte may include an organic solvent and a lithium salt. The organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move, and is not particularly limited. According to exemplary embodiments, a non-aqueous electrolyte may be used as the electrolyte.

[0141] The above non-aqueous electrolyte may include a lithium salt as an electrolyte and an organic solvent. The lithium salt may be, for example, Li + X - can be expressed as . The anion of the lithium salt (X - ) as F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - Examples include:

[0142] The organic solvent may include an organic compound that has sufficient solubility for the lithium salt and additive and does not exhibit reactivity within the battery. For example, the organic solvent may include at least one of a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, and an aprotic solvent.

[0143] Examples of the organic solvent include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate, diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), methylpropyl carbonate, ethylpropyl carbonate, dipropyl carbonate, vinylene carbonate, methylacetate (MA), ethyl acetate (EA), n-propylacetate (n-PA), 1,1-dimethylethyl acetate (DMEA), methyl propionate (MP), ethyl propionate (EP), fluoroethyl acetate (FEA), difluoroethyl acetate (DFEA), trifluoroethyl acetate (TFEA), dibutyl ether, Tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (DEGDME), dimethoxyethane, tetrahydrofuran (THF), 2-methyltetrahydrofuran, ethyl alcohol, isopropyl alcohol, dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, sulfolane, gamma-butyrolactone, and propylene sulfite can be used. These can be used alone or in combination of two or more.

[0144] The above non-aqueous electrolyte may further include an additive. The additive may include, for example, a cyclic carbonate compound, a fluorine-substituted carbonate compound, a sultone compound, a cyclic sulfate compound, a cyclic sulfite compound, a phosphate compound, and a borate compound.

[0145] The above cyclic carbonate compound may include vinylene carbonate (VC), vinyl ethylene carbonate (VEC), etc.

[0146] The above fluorine-substituted cyclic carbonate compound may include fluoroethylene carbonate (FEC), etc.

[0147] The above sultone compounds may include 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, etc.

[0148] The above cyclic sulfate compound may include 1,2-ethylene sulfate, 1,2-propylene sulfate, etc.

[0149] The above cyclic sulfite compound may include ethylene sulfite, butylene sulfite, etc.

[0150] The above phosphate compound may include lithium difluoro bis-oxalato phosphate, lithium difluoro phosphate, etc.

[0151] The borate compound may include lithium bis(oxalate) borate, etc. In some embodiments, the unit cell may not include a separator between the positive and negative electrodes and may include a solid electrolyte. Specifically, a lithium secondary battery including the unit cell may use a solid electrolyte instead of the non-aqueous electrolyte described above. The solid electrolyte is not particularly limited. For example, the solid electrolyte may be an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or a polymer-based solid electrolyte.

[0152] The present disclosure may also relate to the following aspects:

[0153] Side 1) The electrode for a secondary battery may include an electrode current collector; an electrode mixture layer on both sides of the electrode current collector; and an insulating layer on both sides of the electrode current collector, and the electrode for a secondary battery may have an α value of 0 to 1 according to the following equation 1.

[0154] [Formula 1]

[0155]

[0156] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

[0157] Side 2) In side 1, the electrode current collector may include a non-coated portion on which an electrode mixture layer is not disposed, and the insulating layer may be disposed on the non-coated portion.

[0158] Side 3) In side 1, the electrode current collector may include a non-coated portion on which an electrode mixture layer is not disposed, and the insulating layer may be disposed to cover a portion of the electrode mixture layer from a portion of the non-coated portion.

[0159] Side 4) In any one of sides 1 to 3, the electrode for the secondary battery may have an α value of 0 to 0.9 according to the above formula 1.

[0160] Side 5) In any one of sides 1 to 4, the electrode for the secondary battery may have an α value according to the above formula 1 greater than 0.

[0161] Side 6) In any one of sides 1 to 5, the secondary battery electrode is T according to the above formula 1 A Value and T B The values ​​may be different.

[0162] Side 7) In any one of sides 1 to 6, the secondary battery electrode has |T according to the above formula 1 A - T B | The value can be greater than 0 and less than or equal to 2.

[0163] Side 8) In any one of sides 1 to 7, the secondary battery electrode is T according to the above formula 1 A The value can be between 5 and 15.

[0164] Side 9) In any one of sides 1 to 8, the secondary battery electrode is T according to the above formula 1 B The value can be between 5 and 15.

[0165] Side 10) In any one of sides 1 to 9, the electrode for the secondary battery may have a W value of 3 to 10 according to the above formula 1.

[0166] Side 11) In any one of sides 1 to 10, the insulating layer may include an insulating polymer.

[0167] Aspect 12) In aspect 11, the insulating polymer may include at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polyvinylacetate (PVA), polyethylene oxide (PEO), cellulose acetate (CA), cellulose acetate butyrate (CAB), and copolymers thereof.

[0168] Aspect 13) In aspect 11, the insulating polymer may include a graft copolymer of a first polymer and a second polymer. The first polymer may be polyimide (PI) or polyamideimide (PAI), and the second polymer may be styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR).

[0169] Aspect 14) A lithium secondary battery according to an embodiment may include an electrode for a secondary battery according to any one of aspects 1 to 13.

[0170] Example

[0171] 1. Electrode manufacturing

[0172] 1) Reference example

[0173] A slurry containing a positive electrode active material (nickel-cobalt-manganese (NCM) lithium oxide) and a binder (polyvinylidene fluoride; PVDF) was applied to both sides of aluminum foil (Al-foil), which is a positive electrode current collector, and then dried at 140°C to 160°C to manufacture a positive electrode including a positive electrode mixture layer on each side of the positive electrode current collector.

[0174] Afterwards, an insulating solution including a PAI-HNBR copolymer, which is a polyamideimide (PAI) grafted with hydrogenated nitrile butadiene rubber (HNBR) as an insulating polymer, was applied to the non-coated portion of the positive electrode current collector on which the positive electrode mixture layer was not formed, and then dried at 140°C to 160°C to form an insulating layer on both sides of the positive electrode current collector. At this time, the insulating layer was formed by the length (L) of the overlapping area (A) covering a part of the positive electrode mixture layer, as shown in Fig. 3. A ) is formed to be 1 mm, and the length (L) of the above overlap area (A) A ) and the length of the anode composite layer (L) T ) was 1:1,000.

[0175] In addition, the thickness of the first insulating layer (T A ), thickness of the second insulating layer (T B ) and the width (W) of the insulating layer are as shown in Table 1 below. In addition, the results of calculating the foil curl parameter (α) value according to Equation 1 below are shown in Table 1 below.

[0176] [Formula 1]

[0177]

[0178] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer formed on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer formed on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

[0179] 2) Example 1

[0180] The electrode of Reference Example 1 manufactured as described above was vacuum dried (VD) at 150°C for 6 hours to manufacture the electrode of Example 1.

[0181] 3) Examples 2 to 6 and Comparative Examples 1 to 6

[0182] The thickness of the first insulating layer (T) A), thickness of the second insulating layer (T B ), the electrodes and secondary batteries of Examples 2 to 6 and Comparative Examples 1 to 6 were manufactured according to the same method as Example 1, except that the values ​​of the width (W) of the insulating layer and the foil curl parameter (α) were different.

[0183] 2. Electrode Evaluation

[0184] 1) Evaluation of bending level

[0185] The results of evaluating the warpage level of the electrode manufactured as described above are shown in FIGS. 6 to 9 and Table 1 below. FIG. 6 is a drawing showing the results of confirming the warpage level of the electrode for a secondary battery according to a reference example, FIG. 7 is a drawing showing the results of confirming the warpage level of the electrode for a secondary battery according to Example 1, FIG. 8 is a drawing showing the results of confirming the warpage level in the electrode for a secondary battery according to Example 2, and FIG. 9 is a drawing showing the results of confirming the warpage level in the electrode for a secondary battery according to a comparative example.

[0186] At this time, the bending level of the electrode was evaluated by measuring the degree of bending (the degree of separation from the ground) of the non-conductive portion (electrode tab portion) of the electrode current collector in mm using a ruler.

[0187] 2) Assembly fairness evaluation

[0188] The tab welding process was performed on the electrodes manufactured as described above, and the presence or absence of defects during the electrode assembly assembly process was determined to evaluate the assembly fairness. Specifically, if the influence of warpage was minimal and there were no problems with the electrode assembly during the tab welding process, it was evaluated as Pass. If the influence of warpage was significant and wrinkle defects (severe level) occurred in the electrode assembly during the tab welding process, it was evaluated as Fail. The results are shown in Table 1 below.

[0189] T A (μm)T B (μm)T A - T B(μm)W(mm)Foil CurlParameter(α)Bending level(mm)Assembly processabilityReference example-----1PassExample 18.449.511.074.50.481PassExample 29.410.91.55.50.832PassExample 39.913.43.52.80.983PassExample 413.5715.11.536.50.993PassExample 518.2120.222.014.50.903PassExample 64.85.70.910.50.953PassComparative example 17.79.61.95.51.054.5FailComparative example 29.812.42.66.51.696FailComparative example 39.815.35.52.81.545FailComparison Example 419.8923.83.915.52.156.5FailComparison Example 59.812.42.610.12.637FailComparison Example 62.854.721.875.51.034.5Fail

[0190] Referring to Table 1 and FIGS. 6 to 9, the electrodes of Comparative Examples 1 to 6 having a foil curl parameter (α) value exceeding 1 had a warpage level of 4.5 mm or more, resulting in severe foil curling, and the assembly processability was also found to be inadequate. On the other hand, the electrodes of Examples 1 to 6 having a foil curl parameter (α) value of 1 or less had a low warpage level of 3 mm or less, and the assembly processability was also found to be excellent.

[0191] Considering these results, it is believed that if the foil curl parameter (α) value according to Equation 1 is controlled to 1 or less in the electrode for a secondary battery, the safety problem caused by a short circuit inside the secondary battery can be alleviated while improving the secondary battery production process.

[0192] [Explanation of symbols]

[0193] 10: Electrode current collector

[0194] 21: First anode composite layer

[0195] 22: Second anode composite layer

[0196] 31: First insulating layer

[0197] 32: Second insulating layer

[0198] 100: Electrode for secondary battery

[0199] T A : Thickness of the first insulating layer

[0200] T B : Second insulating layer thickness

[0201] W: Insulation layer width

[0202] A: Overlap area

[0203] A1: First overlap area

[0204] A2: Second overlap area

[0205] L A : Length of the overlap area

[0206] L T : Length of electrode mixture layer

[0207] As described above, the features of the present invention can be applied in whole or in part to a secondary battery electrode and a lithium secondary battery including the same.

Claims

1. An electrode for a secondary battery comprising: an electrode current collector; an electrode mixture layer on both sides of the electrode current collector; and an insulating layer on both sides of the electrode current collector. The above secondary battery electrode has an α value of 0 to 1 according to the following equation 1. Electrode for secondary batteries. [Formula 1] In the above equation 1, α is the foil curl parameter, and T A is the thickness value in μm of the insulating layer on one side of the electrode collector, and T B is the thickness value in μm of the insulating layer on the other side of the electrode collector, and W is the width value in mm of the insulating layer.

2. In paragraph 1, The above electrode current collector includes a non-conductive portion on which an electrode composite layer is not disposed on the surface, The above insulating layer is disposed on the non-conductive part, Electrode for secondary batteries.

3. In paragraph 1, The above electrode current collector includes a non-conductive portion on which an electrode composite layer is not disposed on the surface, The insulating layer is arranged to cover a part of the electrode composite layer from a part of the non-conductive part. Electrode for secondary batteries.

4. In paragraph 1, The above secondary battery electrode has an α value of 0 to 0.9 according to the above formula 1. Electrode for secondary batteries.

5. In paragraph 1, The electrode for the secondary battery has an α value greater than 0 according to the above formula 1. Electrode for secondary batteries.

6. In paragraph 1, The above secondary battery electrode is T according to the above formula 1 A Value and T B The values ​​are different, Electrode for secondary batteries.

7. In paragraph 1, The above secondary battery electrode is |T according to the above formula 1 A - T B | The value is greater than 0 and less than or equal to 2, Electrode for secondary batteries.

8. In paragraph 1, The above secondary battery electrode is T according to the above formula 1 A The value is between 5 and 15, Electrode for secondary batteries.

9. In paragraph 1, The above secondary battery electrode is T according to the above formula 1 B The value is between 5 and 15, Electrode for secondary batteries.

10. In paragraph 1, The above secondary battery electrode has a W value of 3 to 10 according to the above formula 1. Electrode for secondary batteries.

11. In paragraph 1, The above insulating layer comprises an insulating polymer, Electrode for secondary batteries.

12. In paragraph 11, The insulating polymer comprises at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polyvinylacetate (PVA), polyethylene oxide (PEO), cellulose acetate (CA), cellulose acetate butyrate (CAB), and copolymers thereof. Electrode for secondary batteries.

13. In paragraph 11, The above insulating polymer comprises a graft copolymer of a first polymer and a second polymer, The above first polymer is polyimide (PI) or polyamideimide (PAI), The second polymer is styrene-butadiene rubber (SBR) or hydrogenated nitrile-butadiene rubber (HNBR). Electrode for secondary batteries.

14. A secondary battery electrode comprising any one of claims 1 to 13. Lithium secondary battery.

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