Electrode laminate, and electrode assembly and secondary battery comprising same

Abstract

The present invention relates to an electrode laminate, an electrode assembly and a secondary battery, the electrode laminate enabling, in a secondary battery, for example, a secondary battery comprising an electrode assembly in the form of an all-solid-state battery stack or a jelly-roll structure, a volume change of a first electrode (for example: an anode) according to charging and discharging to be buffered, thereby ensuring excellent safety and electrochemical properties of the secondary battery.

Description

Electrode laminate, electrode assembly including the same, and secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 2024-0184440 filed December 12, 2024 and Korean Patent Application No. 2025-0191997 filed December 5, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present application relates to an electrode laminate, an electrode assembly, and a secondary battery capable of buffering the volume change of the negative electrode due to charging and discharging of the secondary battery, thereby ensuring excellent safety and electrochemical characteristics of the secondary battery.

[0005] Recently, as the application areas of lithium-ion batteries have rapidly expanded to include power supply for large-area devices such as automobiles and power storage systems, there is a growing demand for lithium-ion batteries that are high-capacity, high-output, long-life, and highly stable.

[0006] In particular, while various active materials are applied to achieve high capacity, the problem of volume expansion caused by the active materials arises as lithium-ion batteries undergo numerous charge-discharge cycles. Due to this volume expansion, the lifespan characteristics of lithium-ion batteries can decrease rapidly.

[0007] The objective of the present application is to provide an electrode laminate, an electrode assembly, and a secondary battery capable of effectively buffering the volume expansion of the battery due to charging and discharging, thereby minimizing problems caused by volume expansion.

[0008] One embodiment of the present application may relate to an electrode laminate comprising: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode including a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector; and an insulating layer provided between the first electrode and the second electrode and including an elastic polymer, wherein the first electrode material layer comprises one or more of a non-cathode coating layer, a lithium layer, and a silicon-based active material layer, and the insulating layer has a thickness of 10 μm to 100 μm, and as a result of performing a compression test according to the standard method of ASTM D3574, the strain in the thickness direction is 10% to 90% under a load of 1 MPa.

[0009] In one embodiment, the first electrode material layer is provided on one surface of the first electrode current collector, the second electrode material layer is provided on one surface of the second electrode current collector, and the insulating layer may be provided between the other surface of the first electrode current collector where the first electrode material layer is not provided and the other surface of the second electrode current collector where the second electrode material layer is not provided.

[0010] In one embodiment, the elastic polymer may include one or more of a polyolefin-based polymer, a polyurethane-based polymer, and a silicone-based polymer.

[0011] In one embodiment, the insulating layer may be included in the form of foam in which the elastic polymer is foamed.

[0012] In one embodiment, the insulating layer may further include an insulating polymer that does not have a foamed form.

[0013] In one embodiment, the electrode laminate may further include an insulating additional layer comprising an insulating polymer and disposed between the first electrode and the second electrode.

[0014] In one embodiment, the insulating polymer may not have a foamed form.

[0015] In one embodiment, the insulating additional layer may be laminated on the insulating layer.

[0016] One embodiment of the present application may relate to an electrode assembly comprising a plurality of stacked electrode stacks and an ion transport layer, wherein the ion transport layer is provided between adjacent electrode stacks among the electrode stacks, and the electrode stack comprises: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode having a polarity different from that of the first electrode including a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector; and an insulating layer provided between the first electrode and the second electrode and comprising an elastic polymer, wherein the insulating layer has a thickness of 10 μm to 100 μm and, as a result of conducting a compression test according to the standard method of ASTM D3574, the strain in the thickness direction is 10% to 90% under a load of 1 MPa.

[0017] One embodiment of the present application may relate to an electrode assembly comprising a plurality of stacked electrode stacks, an intermediate electrode provided between adjacent electrode stacks among the electrode stacks, and an ion transport layer provided between the intermediate electrode and the adjacent electrode stacks, wherein the electrode stack comprises: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode having the same polarity as the first electrode, comprising a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector; and an insulating layer provided between the first electrode and the second electrode and comprising an elastic polymer, wherein the insulating layer has a thickness of 10 μm to 100 μm and, as a result of conducting a compression test according to the standard method of ASTM D3574, the strain in the thickness direction is 10% to 90% under a load of 1 MPa, and the intermediate electrode has a polarity different from that of the first electrode and the second electrode.

[0018] In one embodiment, the inter-electrode may include an inter-current collector and an inter-electrode material layer provided on both sides of the inter-current collector.

[0019] One embodiment of the present application may relate to an electrode assembly comprising an electrode laminate and an ion transport layer provided on the electrode laminate, wherein the electrode laminate comprises: a first electrode comprising a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode comprising a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector, having a polarity different from that of the first electrode; and an insulating layer provided between the first electrode and the second electrode and comprising an elastic polymer, wherein the electrode laminate and the ion transport layer are wound together to form a jelly-roll structure.

[0020] In one embodiment, the ion transport layer may be a porous separator or a solid electrolyte layer.

[0021] In one embodiment, the solid electrolyte layer may include a sulfide-based solid electrolyte.

[0022] The present application can provide an electrode laminate, an electrode assembly, and a secondary battery that can effectively buffer the volume expansion of the battery due to charging and discharging, thereby minimizing problems caused by volume expansion.

[0023] FIG. 1 is a schematic cross-section of an electrode laminate according to one embodiment of the present application (discharge state).

[0024] FIG. 2 is a schematic cross-section of an electrode laminate according to one embodiment of the present application (charged state).

[0025] FIG. 3 is a schematic cross-section of an electrode laminate according to another embodiment of the present application (discharge state).

[0026] FIG. 4 schematically shows a cross-section of an electrode laminate according to one embodiment of the present application, illustrating an example of an insulating additional layer (discharge state).

[0027] FIG. 5 schematically shows a cross-section of an electrode laminate according to another embodiment of the present application, illustrating another example of an insulating additional layer (discharge state).

[0028] FIG. 6 is a schematic cross-sectional view of an electrode assembly according to one embodiment of the present application (discharge state).

[0029] FIG. 7 is a schematic cross-sectional view of an electrode assembly according to another embodiment of the present application (discharge state).

[0030] FIG. 8 is a schematic cross-sectional view of an electrode assembly according to another embodiment of the present application (discharge state).

[0031] FIG. 9 is a graph showing the results of evaluating the strain in the thickness direction according to the applied load by conducting a compression test on the polyethylene resin elastic foam sheet used as an insulating layer in Example 1 of the present application using the standard method of ASTM D3574.

[0032] FIG. 10 is an X-ray Computed Tomography (XCT) image showing a top view of an electrode assembly in the shape of a jelly-roll structure when charged to a State of Charge (SOC) of 100% in the cylindrical secondary battery of Example 1 of the present application.

[0033] FIG. 11 is an X-ray CT image showing a top view of an electrode assembly in the shape of a jelly-roll structure when charged to SOC 100% in a cylindrical secondary battery of Comparative Example 1 of the present application.

[0034] FIG. 12 is a graph showing the pattern of change in cell potential during two charge-discharge cycles for the cylindrical secondary batteries of Example 1 and Comparative Example 1 of the present application.

[0035] FIG. 13 is a graph showing the evaluation results of discharge capacity per cycle by conducting charge-discharge tests on the cylindrical secondary batteries of Example 1 and Comparative Example 1 of the present application.

[0036] Hereinafter, various embodiments of the present application will be described in detail. The present application may be implemented in different forms and is not limited to the embodiments described herein.

[0037] Unless specifically limited in this specification, the physical properties mentioned herein may be measured in an environment of room temperature and atmospheric pressure. In this specification, room temperature refers to a natural temperature without artificial manipulation and may be 10°C to 30°C, 20°C to 28°C, or 22°C to 26°C, and in one example, 25°C. In this specification, atmospheric pressure refers to a natural pressure without artificial manipulation and may be 700 mmHg to 800 mmHg or 720 mmHg to 780 mmHg, and in one example, 760 mmHg. Unless specifically limited in this specification, the units of physical properties may be in the SI unit system.

[0038] The present application will be described in detail below with reference to the drawings of this specification. However, the present application is not limited by the drawings of this specification. The drawings shown in this application are in accordance with embodiments of the present application, and the ratios of the width, height, or thickness (or height) of each component are intended to describe the present application in detail and may differ from the actual. Additionally, in the coordinate system shown in the drawings, each axis may be perpendicular to each other, the direction indicated by the arrow may be the + direction, and the direction exactly opposite to the direction indicated by the arrow (a direction rotated 180 degrees) may be the - direction.

[0039] Unless specifically limited in the present specification, the direction in which each component of the electrode laminate is laminated may be referred to as the first direction (D1). The length of each component according to the first direction (D1) may be the thickness. That is, the first direction (D1) may mean the thickness direction. Meanwhile, as will be described later, if the electrode laminate is wound to have a jelly-roll structure shape, the first direction (D1) may mean the radial direction with respect to the center of the winding. The second direction (D2) may intersect the first direction (D1) and may exist on a plane normal to the first direction (D1). Additionally, the third direction (D3) may intersect the second direction (D2) and may exist on a plane normal to the first direction (D1).

[0040] FIG. 1 is a schematic cross-sectional view of an electrode stack (11) according to one embodiment of the present application (discharge state). FIG. 2 is a schematic cross-sectional view of an electrode stack (11) according to one embodiment of the present application (charge state). FIG. 3 is a schematic cross-sectional view of an electrode stack (12) according to another embodiment of the present application (discharge state).

[0041] The electrode laminate (11, 12) according to the present application may include a first electrode (101, 102) and a second electrode (201, 202). The first electrode (101, 102) may include a first electrode current collector (110) and a first electrode material layer (120) provided on one or both sides of the first electrode current collector (110). The second electrode (201, 202) may include a second electrode current collector (210) and a second electrode material layer (220) provided on one or both sides of the second electrode current collector (210).

[0042] In one embodiment, the first electrode (101, 102) and the second electrode (201, 202) may have the same polarity. That is, the first electrode (101, 102) and the second electrode (201, 202) may be negative electrodes. In another example, the first electrode (101, 102) and the second electrode (201, 202) may be positive electrodes.

[0043] In one embodiment, the first electrode (101, 102) and the second electrode (201, 202) may have different polarities. That is, the first electrode (101, 102) may be a negative electrode and the second electrode (201, 202) may be a positive electrode. In another example, the first electrode (101, 102) may be a positive electrode and the second electrode (201, 202) may be a negative electrode.

[0044] In one embodiment, one of the first electrode (101, 102) and the second electrode (201, 202) may be a negative electrode. For example, the first electrode (101, 102) may be a negative electrode. Here, the second electrode (201, 202) may be a negative electrode with the same polarity as the first electrode (101, 102) and a positive electrode with a different polarity.

[0045] Below, the case where the first electrode (101, 102) is a negative electrode and the second electrode (201, 202) is a positive electrode is described. That is, the first electrode (101, 102) is a negative electrode, the first electrode current collector (110) is a negative current collector, and the first electrode material layer (120) may be a negative electrode material layer. In addition, the second electrode (201, 202) is a positive electrode, the second electrode current collector (210) is a positive current collector, and the second electrode material layer (220) may be a positive electrode material layer.

[0046] However, if the first electrode (101, 102) is an anode, the following description regarding the second electrode (201, 202) may be referenced, and if the second electrode (201, 202) is a cathode, the following description regarding the first electrode (101, 102) may be referenced.

[0047] In one embodiment, the first electrode current collector (110) is a negative current collector and is electrically conductive without causing chemical changes in the electrode laminate (11, 12), and its type, size, and shape are not particularly limited. The negative current collector may include, for example, one or more of copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), magnesium (Mg), iron (Fe), titanium (Ti), cobalt (Co), chromium (Cr), zinc (Zn), germanium (Ge), indium (In), and stainless steel. The negative current collector may be composed of one of the metals mentioned above, or may be composed of an alloy including two or more of the metals mentioned above, or may be coated with a coating material. The negative current collector may have a form such as a plate, mesh, or foil, for example. The thickness of the negative current collector may be 1 μm or more and 50 μm or less.

[0048] In one embodiment, the first electrode material layer (120) may be a negative electrode material layer, and the negative electrode material layer may include one or more of a non-negative electrode coating layer, a lithium layer, and a silicon-based active material layer.

[0049] The above-mentioned anode-free coating layer may be a coating layer formed between a negative current collector and a solid electrolyte layer (e.g., see ion transport layer (400) in FIG. 6) in an anode-free all-solid-state battery. An anode-free all-solid-state battery may refer to an all-solid-state battery in which lithium is adsorbed in the anode-free coating layer during charging, and after the charging capacity of the anode-free coating layer is exceeded, lithium is plated between the negative current collector and the anode-free coating layer to form a lithium precipitation layer, and during discharge, the lithium in the anode-free coating layer and the lithium precipitation layer is ionized and moves toward the positive electrode.

[0050] The above-described non-cathode coating layer can cover the lithium precipitation layer formed on the negative electrode current collector during the charging process, thereby acting as a protective layer for the lithium precipitation layer and suppressing the growth of lithium dendrites. Through this, short circuits and capacity degradation of the all-solid-state battery can be suppressed, and performance can be improved. The lithium precipitation layer is formed during the charging process of the non-cathode all-solid-state battery, and differs from the lithium layer in the lithium metal battery described later in that the lithium precipitation layer is not formed in the initial discharge state where charging is not performed.

[0051] The above-mentioned non-cathode coating layer may include a lithium-affinity material. The lithium-affinity material may include one or more of amorphous carbon, a lithium-affinity element, and a lithium-affinity compound.

[0052] The above amorphous carbon may include, for example, one or more of carbon black, acetylene black, furnace black, Ketjen black, and graphene, but is not limited thereto.

[0053] The above lithium-affinity element may include a metal, a metalloid element, or a combination thereof that forms an alloy or compound with lithium. The above lithium-affinity element may include, for example, one or more of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0054] The above lithium-affinity compound may be a substance in the form of a compound capable of forming a compound with lithium or stabilizing lithium. The above lithium-affinity compound may include one or more of lithium carbonate, lithium titanate, oxides, nitrides, halides, sulfides, carbides, hydrides, and hydroxides of the above lithium-affinity element.

[0055] The above-mentioned non-cathode coating layer may include a binder. The binder may include, for example, one or more of water-based binders and organic-based binders. The binder may include, for example, one or more of polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinylidene fluoride, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylate styrene-butadiene rubber, epoxy resin, and nylon. For example, the water-based binder may be styrene-butadiene rubber, carboxymethylcellulose, or any combination thereof. The above organic binder may include, for example, one or more of polytetrafluoroethylene and polyvinylidene fluoride.

[0056] The above-mentioned cathode-coating layer can be manufactured, for example, by drying a slurry. The slurry forming the cathode-coating layer may contain a solvent in addition to the material included in the cathode-coating layer. That is, the material included in the cathode-coating layer may be dispersed in the solvent. The solvent may include one or more of water and N-methylpyrrolidone (NMP), but is not limited thereto.

[0057] The above-mentioned non-cathode coating layer may include other additives. The above-mentioned other additives may include one or more of fillers, coating agents, dispersants, and ion conductivity aids, provided that they do not impede the purpose of the present invention, but are not limited thereto.

[0058] The lithium layer is used in a lithium metal battery and may include one or more of lithium metal and lithium alloy. The lithium alloy may include one or more of silicon (Si), tin (Sn), aluminum (Al), silver (Ag), gold (Au), and magnesium (Mg) in addition to lithium. The thickness of the lithium layer may be, for example, 10 μm or more to 500 μm or less. In another example, the thickness of the lithium layer may be, for example, 30 μm or more to 200 μm or less. As described above, the lithium layer in a lithium metal battery differs from the lithium precipitate layer in a negative electrode all-solid-state battery in that it exists even in the initial state where charging and discharging have not taken place.

[0059] The above silicon-based active material layer may include a silicon-based active material as a negative electrode active material. Such silicon-based active materials include silicon-carbon composites such as Si, Si alloys, SiC, and SiO. β It may include one or more of (0 < β < 2). In this case, the silicon-based active material layer may have a thickness of, for example, 10 μm to 100 μm, or 20 μm to 80 μm, or 30 μm to 70 μm.

[0060] The silicon-based active material layer may further include other types of negative electrode active materials together with the silicon-based active material. In this case, based on the total weight of the negative electrode active material included in the silicon-based active material layer, the silicon-based active material may be included in an amount of 5 weight% or more, 10 weight% or more, or less than 100 weight%.

[0061] The types of such additional cathode active materials are not particularly limited, and the additional cathode active materials may include one or more of the following: carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Al, Sn, Pb, Sb, Zn, Bi, In, Mg, Ga, Cd, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium such as SnO2, vanadium oxide, and lithium vanadium oxide; and composites comprising the metallic compounds and carbonaceous materials such as Sn-C composites. Regarding the amorphous carbon, reference may be made to the amorphous carbon included in the non-cathode coating layer as the aforementioned lithium-affinity material.

[0062] The additional negative electrode active material described above may be included in an amount of 60 to 99 weight%, or 70 to 99 weight%, or 80 to 98 weight% based on the total weight of the silicon-based active material layer.

[0063] Meanwhile, the silicon-based active material layer may include a conductive material and a binder together with a negative electrode active material such as the silicon-based active material.

[0064] The conductive material included in the above silicon-based active material layer is a component for further enhancing the conductivity of the active material, and such conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, the conductive material may include one or more of the following: carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive nanomaterials such as carbon nanofibers or carbon nanotubes; fluorinated carbon powder; conductive powder such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0065] The conductive material may be included in an amount of 1% to 20% by weight, or 1% to 15% by weight, or 1% to 10% by weight, based on the total weight of the silicon-based active material layer.

[0066] The binder optionally included in the above silicon-based active material layer is a component that assists in the bonding of the negative electrode active material and the conductive material, and in the bonding to the current collector. The binder may include, for example, one or more of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, nitrile-based rubber, styrene-butadiene rubber, fluororubber, and two or more copolymers selected from these. The binder may be included in an amount of 1% to 20% by weight, or 1% to 15% by weight, or 1% to 10% by weight, based on the total weight of the silicon-based active material layer.

[0067] The above silicon-based active material layer may include a solid electrolyte. Specifically, the solid electrolyte may be included in an amount of 1% to 50% by weight based on the total weight of the silicon-based active material layer. For the solid electrolyte, one may refer to the details regarding the solid electrolyte included in the solid electrolyte layer described below.

[0068] In one embodiment, the second electrode current collector (210) is an anode current collector and is electrically conductive without causing chemical changes in the electrode laminate, and its type, size, and shape are not particularly limited. The anode current collector may include, for example, one or more of copper (Cu), nickel (Ni), aluminum (Al), vanadium (V), gold (Au), platinum (Pt), chromium (Cr), iron (Fe), zinc (Zn), indium (In), germanium (Ge), lithium (Li), magnesium (Mg), stainless steel, titanium (Ti), and cobalt (Co). The anode current collector may be composed of one of the metals mentioned above, or may be composed of an alloy containing two or more of the metals mentioned above, or may be coated with a coating material. The anode current collector may have a shape such as a plate, mesh, or foil. Meanwhile, the anode current collector may also include a surface treated with carbon, nickel, titanium, silver, etc., on the surface of sintered carbon or aluminum or stainless steel. The thickness of the above positive current collector may be 1 μm or more to 50 μm or less.

[0069] In one embodiment, the second electrode material layer (220) may be a positive active material layer. The positive active material layer may include a positive active material. In addition to the positive active material, the positive active material layer may include one or more of a conductive material, a binder, and a solid electrolyte, and may additionally include an additive in some cases. Regarding the conductive material and binder included in the positive active material layer, reference may be made to the conductive material and binder included in the silicon-based active material layer described above. Meanwhile, regarding the solid electrolyte included in the positive active material layer, reference may be made to the solid electrolyte included in the solid electrolyte layer described later.

[0070] The above-mentioned positive electrode active material may include, for example, one or more of lithium transition metal oxides, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, and vanadium oxide. The above-mentioned lithium transition metal oxide may include one or more of lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide (lithium manganate), and lithium iron phosphate (LFP). The positive electrode active material is not limited thereto and may be any material used as a positive electrode active material in the relevant technical field.

[0071] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (wherein 0.90≤a≤1, and 0≤b≤0.5); Li a Ni 1-b-c Co b B c O 2-α F2(wherein 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0 <α<2); Li a Ni 1-b-c Mn b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li a Ni 1-b-c Co b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a E 1-b B b O 2-c D c (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B bO 4-c D c (In the above formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a CoG b O2(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α F2(wherein 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2(wherein 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2(wherein the above equation, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0 ≤d≤0.5, 0.001≤e≤0.1); Li a NiG bO2 (wherein the above equation, 0.90≤a≤1, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3- f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); it may be a compound represented by any one of the chemical formulas of LiFePO4. In such a compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. As a positive electrode active material, a compound having a coating layer added to the surface of such a compound may be used, or a mixture of the compound described above and the compound having a coating layer added may be used. A coating layer added to the surface of such compounds may contain, for example, a lithium ion conductive oxide. The lithium ion conductive oxide is, for example, LiNbO3, Li4Ti5O 12 Examples include Li3PO4, but are not limited thereto. The compounds forming this coating layer may be amorphous or crystalline. Methods for forming the coating layer may include, for example, spray coating or immersion methods, but can be selected without limitation as long as they do not adversely affect the physical properties of the cathode active material.

[0072] When the above-mentioned cathode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), it may be possible to increase the capacity density of the all-solid-state secondary battery and reduce the metal leaching of the cathode active material in the charged state. Accordingly, the cycle characteristics of the all-solid-state battery in the charged state may be improved.

[0073] The shape of the above-mentioned positive electrode active material may be a particle shape, for example, a sphere, an elliptical sphere, etc. The particle size of the positive electrode active material is not particularly limited and must be within a range applicable to the positive electrode active material of a conventional all-solid-state battery. The content of the positive electrode active material is also not particularly limited and must be within a range applicable to the positive electrode of a conventional all-solid-state battery.

[0074] The electrode laminate (11, 12) according to the present application may include an insulating layer (300) provided between the first electrode (101, 102) and the second electrode (201, 202). Referring to FIGS. 1 and 2, the volume of the electrode material layer (e.g., the first electrode material layer (120)) may expand due to charging, but the insulating layer (300) sufficiently buffers the volume expansion so that problems caused by volume expansion can be minimized.

[0075] When the electrode laminate (11, 12) according to the present application includes an insulating layer (300) having the above characteristics, the insulating layer (300) can be compressed or recovered in response to a significant change in volume of the first electrode (101, 102) (e.g., negative electrode) during charging and discharging due to a first electrode material layer (120) (e.g., negative electrode material layer) comprising one or more of a non-negative electrode coating layer, a lithium layer, and a silicon-based active material layer. By doing so, the overall volume change can be mitigated and buffered, thereby enabling excellent battery life. Specifically, in the electrode laminate (11, 12) comprising a first electrode material layer (120) (e.g., negative electrode material layer) comprising one or more of a non-negative electrode coating layer, a lithium layer, and a silicon-based active material layer, when the insulating layer (300) according to the present application is included, the discontinuity between electrodes of the secondary battery, short circuit, collapse of the center, or poor interface formation between the electrode and the solid electrolyte membrane can be suppressed.

[0076] In the case of a solid-state secondary battery in which a plurality of electrode stacks (11, 12) or electrode assemblies (e.g., electrode assembly (21) of FIG. 6 and electrode assembly (22) of FIG. 7) are stacked in the stacking direction, or a cylindrical secondary battery in which a plurality of electrodes are stacked in the diameter direction, the volume change is more extreme, so it may be more advantageous to include an insulating layer (300) according to the present application.

[0077] In another example, the thickness of the insulating layer (300) may be 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, or 65 μm or more, or 95 μm or less, 90 μm or less, 85 μm or less, 80 μm or less, or 75 μm or less.

[0078] In another example, the insulating layer (300) may have a thickness-direction strain of 15% or more, 20% or more, 25% or more, 30% or more, or 35% or more, or 80% or less, 70% or less, 60% or less, or 50% or less as a result of a compression test performed using the standard method of ASTM D3574. The insulating layer (300), defined by the thickness-direction strain under the 1MPa load, electrically insulates the first electrode (101, 102) and the second electrode (201, 202) while exhibiting a certain level of elasticity and resilience in the thickness direction.

[0079] The insulating layer (300) may include, for example, one or more of a polyolefin-based polymer, a polyurethane-based polymer, and a silicone-based polymer. In a more specific example, the insulating layer (300) may be included in the form of a foam in which the polymer is foamed to exhibit elasticity and resilience defined by the strain in the thickness direction. In a more specific example, the insulating layer (300) may be in the form of a sheet in which the polymer is foamed with a foaming agent such as ADCA (Azodicarbonamide), for example, and may additionally be in the form of a foamed sheet that is crosslinked under electron beam irradiation. By forming it into such a foamed sheet form, the insulating layer (300) may exhibit a high level of elasticity and resilience capable of buffering large volume changes of the cathode along with an appropriate thickness.

[0080] The insulating layer (300) may include only an elastic polymer in the form of a foamed foam. In other examples, the insulating layer (300) may include an elastic polymer in the form of a foamed foam and an insulating polymer that does not have a foamed form. The type of insulating polymer is not particularly limited and can be determined obviously by considering appropriate compatibility and insulation properties with the elastic polymer. In other examples, the insulating polymer may be a polymer of the same type as the elastic polymer, provided that it does not have a separate foamed form or may be included in the form of an insulating film that is not imparted elasticity by a separate foaming process.

[0081] Referring to FIGS. 1 and 2, in the first electrode (101) of the electrode stack (11), the first electrode material layer (120) may be provided on one side of the first electrode current collector (110). In the second electrode (201), the second electrode material layer (220) may be provided on one side of the second electrode current collector (210). Here, the insulating layer (300) may be provided between the other side of the first electrode current collector (110) where the first electrode material layer (120) is not provided and the other side of the second electrode current collector (210) where the second electrode material layer (220) is not provided.

[0082] Referring to FIG. 3, in the first electrode (102) of the electrode stack (12), the first electrode material layer (120) may be provided on both sides of the first electrode current collector (110). In the second electrode (202), the second electrode material layer (220) may be provided on both sides of the second electrode current collector (210). Here, an insulating layer (300) may be provided between the first electrode material layer (120) and the second electrode material layer (220) that are adjacent to each other.

[0083] FIG. 4 schematically shows a cross-section of an electrode laminate (13) according to one embodiment of the present application, illustrating an example of an insulating additional layer (350) (discharge state). FIG. 5 schematically shows a cross-section of an electrode laminate (14) according to another embodiment of the present application, illustrating another example of an insulating additional layer (350) (discharge state).

[0084] The electrode laminate (13, 14) according to the present application may include an insulating additional layer (350) provided between the first electrode (101) and the second electrode (201). The insulating additional layer (350) may include the aforementioned insulating polymer. Meanwhile, the electrode laminate (13, 14) may include an insulating layer (300) containing an elastic polymer in the form of a foamed foam. Here, the elastic polymer may be described above. Additionally, in the electrode laminate (13, 14), the insulating additional layer (350) may be laminated on the insulating layer (300). Unless otherwise defined in this specification, when the electrode laminate (13, 14) according to the present application includes the insulating layer (300) and the insulating additional layer (350), the thickness direction strain under the aforementioned constant load may be defined for the sum of the thicknesses of the insulating layer (300) and the insulating additional layer (350).

[0085] Referring to FIG. 4, an insulating additional layer (350) in the electrode laminate (13) may be provided between the insulating layer (300) and the second electrode (201). However, it is not limited thereto, and the insulating additional layer (350) may be provided between the insulating layer (300) and the first electrode (101).

[0086] Referring to FIG. 5, the electrode laminate (14) may include a plurality of insulating layers (300). The insulating layers (300) may include a first insulating layer (300a) and a second insulating layer (300b). An insulating additional layer (350) may be provided between the first insulating layer (300a) and the second insulating layer (300b). The polymers included in the first insulating layer (300a) and the second insulating layer (300b) may be the same or different from each other.

[0087] FIG. 6 is a schematic cross-sectional view of an electrode assembly (21) according to one embodiment of the present application (discharge state).

[0088] Referring to FIG. 6, an electrode assembly (21) according to one embodiment of the present application may include a plurality of stacked electrode stacks (11) and one or more ion transport layers (400). The ion transport layer (400) may be provided between adjacent electrode stacks (11) among the electrode stacks (11). Here, the description of the electrode stacks (11) may be referenced to the description of the electrode stacks (11, 12, 13, 14) above, unless inconsistent. For example, the electrode stacks (11) may include a first electrode (101), a second electrode (201), and an insulating layer (300).

[0089] Referring to FIG. 6, the polarity of the first electrode (101) and the second electrode (201) may be different. For example, the first electrode (101) may be a negative electrode and the second electrode (201) may be a positive electrode. In another example, the first electrode (101) may be a positive electrode and the second electrode (201) may be a negative electrode.

[0090] Referring to FIG. 6, the ion transfer layer (400) may be provided between the second electrode material layer (220) and the first electrode material layer (120). Specifically, the ion transfer layer (400) may be in contact with the first electrode material layer (220) and the first electrode material layer (120) in at least some area.

[0091] In one embodiment, the ion transfer layer (400) may refer to a layer that transfers ions (e.g., lithium ions) between the positive and negative electrodes during charging and discharging of the secondary battery. For example, the ion transfer layer (400) may be a solid electrolyte layer or a porous separator. Here, if the secondary battery is an all-solid-state battery, the ion transfer layer (400) may be a solid electrolyte layer. Additionally, if the secondary battery uses a liquid electrolyte (so-called electrolyte), the ion transfer layer (400) may be a porous separator.

[0092] The above solid electrolyte layer may include one or more of, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes. The above solid electrolyte layer may include a sulfide-based solid electrolyte for the purpose of improving ion conductivity.

[0093] The above sulfide-based solid electrolyte is, for example, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li2S-SiS2-P2S5-LiI, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers), Z is one of Ge, Zn, or Ga, L i2 S-GeS2, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I xIt may include one or more selected from (0≤x≤2). Sulfide-based solid electrolytes can be manufactured by processing starting materials, such as Li2S and P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In the present invention, the sulfide-based solid electrolyte may, for example, include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0094] The above sulfide-based solid electrolyte is, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤2), and Li 7-x PS 6-x I x It may include an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may include an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0095] The oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, the oxide-based solid electrolyte may be an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP-based compounds, LATP-based compounds, Li1 +x Ti 2-x Al x Siy (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where, 0≤x≤1, 0≤y≤1), LiTi x Zr 2-x It may include one or more of (PO4)3 (wherein, 0≤x≤1, 0≤y≤1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, nasicon-based compounds and LLZO-based compounds, but is not limited thereto.

[0096] The above-mentioned polymer-based solid electrolyte may have a form in which a polymer resin is added to a solvated lithium salt, that is, a composite of a lithium salt and a polymer resin. The lithium salt described below may be referenced for the lithium salt.

[0097] The porous membrane described above may be used in the form of a sheet, multilayer membrane, microporous film, woven fabric, or nonwoven fabric, using olefin-based polymers such as polyethylene and polypropylene, or glass fibers, but is not necessarily limited thereto. However, it may be preferable to use porous polyethylene or porous glass fiber nonwoven fabric (glass filter) as the membrane, and it may be even more preferable to use porous glass filter (glass fiber nonwoven fabric) as the membrane. The membrane may be an insulating thin film having high ion permeability and mechanical strength. The pore diameter of the membrane may generally be in the range of 0.01 to 10 μm, and the thickness may generally be in the range of 5 to 300 μm, but is not limited thereto.

[0098] FIG. 7 is a schematic cross-sectional view of an electrode assembly (22) according to another embodiment of the present application (discharge state).

[0099] Referring to FIG. 7, an electrode assembly (22) according to another embodiment of the present application may include a plurality of stacked electrode stacks (15), an intermediate electrode (500), and an ion transport layer (400). The intermediate electrode (500) may be provided between adjacent electrode stacks (15) among the electrode stacks (15). The ion transport layer (400) may be provided between the intermediate electrode (500) and the adjacent electrode stacks (15). Here, the description of the electrode stacks (15) may refer to the aforementioned electrode stacks (11, 12, 13, 14) unless inconsistent. For example, the electrode stacks (15) may include a first electrode (101), a second electrode (201), and an insulating layer (300). Also, the description of the ion transport layer (400) may refer to the aforementioned ion transport layer (400) unless inconsistent.

[0100] Referring to FIG. 7, the polarity of the first electrode (101) and the second electrode (201) may be the same. For example, the first electrode (101) and the second electrode (201) may be negative electrodes. In another example, the first electrode (101) and the second electrode (201) may be positive electrodes.

[0101] Referring to FIG. 7, the polarity of the inter-electrode (500) may be different from the polarity of the first electrode (101) and the second electrode (201). For example, if the first electrode (101) and the second electrode (201) are negative electrodes, the inter-electrode (500) may be positive electrode. In another example, if the first electrode (101) and the second electrode (201) are positive electrodes, the inter-electrode (500) may be negative electrode.

[0102] Referring to FIG. 7, the inter-electrode (500) may include an inter-electrode current collector (510) and an inter-electrode material layer (520) provided on both sides of the inter-electrode current collector (510). Here, the electrode current collector (510) may refer to the description of the aforementioned negative electrode current collector or positive electrode current collector depending on the polarity of the inter-electrode (500). Additionally, the electrode material layer (520) may refer to the description of the aforementioned negative electrode material layer or positive electrode material layer depending on the polarity of the inter-electrode (500).

[0103] Referring to FIG. 7, the ion transfer layer (400) may be provided between the second electrode material layer (220) and the intermediate electrode material layer (520). Additionally, the ion transfer layer (400) may also be provided between the first electrode material layer (120) and the intermediate electrode material layer (520). Specifically, the ion transfer layer (400) may be in contact with the second electrode material layer (220) and the intermediate electrode material layer (520) in at least a portion of the area. Additionally, the ion transfer layer (400) may be in contact with the first electrode material layer (120) and the intermediate electrode material layer (520) in at least a portion of the area.

[0104] FIG. 8 is a schematic cross-sectional view of an electrode assembly (23) according to another embodiment of the present application (discharge state).

[0105] Referring to FIG. 8, an electrode assembly (23) according to another embodiment of the present application may include an electrode stack (11) and an ion transport layer (400). The ion transport layer (400) may be provided on the electrode stack (11). Here, the description of the electrode stack (11) may be referenced to the aforementioned electrode stacks (11, 12, 13, 14, 15) unless inconsistent. For example, the electrode stack (11) may include a first electrode (101), a second electrode (201), and an insulating layer (300). Also, the description of the ion transport layer (400) may be referenced to the aforementioned ion transport layer (400) unless inconsistent.

[0106] Referring to FIG. 8, the polarity of the first electrode (101) and the second electrode (201) may be different. For example, the first electrode (101) may be a negative electrode and the second electrode (201) may be a positive electrode. In another example, the first electrode (101) may be a positive electrode and the second electrode (201) may be a negative electrode.

[0107] A secondary battery according to one embodiment of the present application may include the aforementioned electrode stack (11, 12, 13, 14, 15) or electrode assembly (21, 22, 23). The secondary battery may be an all-solid-state secondary battery. In another example, the secondary battery may be a secondary battery using a liquid electrolyte. The secondary battery may be classified as a cylindrical secondary battery, a pouch-type secondary battery, or a prismatic secondary battery depending on its shape.

[0108] An all-solid-state secondary battery according to another embodiment of the present application may include, for example, at least one monocell, bicell, or multistack cell. The electrode assembly (21, 22, 23) may have a structure corresponding to at least a part of the aforementioned monocell, bicell, or multistack cell.

[0109] The above monocell refers to a unit cell having different types of electrodes located on both sides in a structure in which one or more anode layers and one or more cathode layers are stacked with a solid electrolyte layer interposed therein. The above monocell may have a structure in which, for example, an anode layer, a solid electrolyte layer, and a cathode layer are stacked sequentially.

[0110] The above bicell refers to a unit cell in which the types of electrodes located on both sides are the same in a structure in which one or more anode layers and one or more cathode layers are stacked with a solid electrolyte layer interposed therein. The above bicell may have a structure in which, for example, a cathode layer, a solid electrolyte layer, an anode layer, a solid electrolyte layer, and a cathode layer are stacked sequentially, or a structure in which an anode layer, a solid electrolyte layer, a cathode layer, a solid electrolyte layer, and an anode layer are stacked sequentially.

[0111] The above multi-stack cell refers to a cell having a stacked structure in which a solid electrolyte layer is interposed between an anode layer and a cathode layer, and this structure is repeated three or more times. The above electrode assembly (21, 22) can be sealed in a pouch.

[0112] A secondary battery according to one embodiment of the present application may include electrode assemblies (21, 22, 23) formed as a jelly-roll structure. In addition to the configurations shown in FIGS. 6 to 8, the electrode assemblies (21, 22, 23) may additionally include appropriate configurations to enable operation as a secondary battery by being formed as a jelly-roll structure. For example, the electrode assemblies (21, 22) shown in FIG. 6 or FIG. 7 may further have an ion transport layer (400) provided on the outermost surface, and may be formed as a jelly-roll structure to enable operation as a secondary battery.

[0113] In one example, in an electrode assembly (21, 22, 23) formed as a jelly-roll structure, the electrode stack (11, 12, 13, 14, 15) and the ion transport layer (400) can be wound together. That is, the electrode stack (11, 12, 13, 14, 15) and the ion transport layer (400) can be wound together to form a jelly-roll structure. For example, referring to the electrode assembly (23) of FIG. 8, the electrode stack (11) and the ion transport layer (400) can be wound together, and the ion transport layer (400) can be formed so that the first electrode (101) and the second electrode (201) within the electrode stack (11) do not come into direct contact with each other, thereby allowing the jelly-roll structure to be operated as a secondary battery.

[0114] In one example, when the electrode assembly (21, 22, 23) is formed as a jelly-roll structure, the ion transport layer (400) may be a solid electrolyte layer or a porous separator. However, more preferably, the ion transport layer (400) may be a porous separator.

[0115] In one example, an anode tab and a cathode tab may protrude from the upper and lower surfaces of a jelly-roll structure, respectively, and an electrode assembly in the form of such a jelly-roll structure may be housed in a case (cylindrical, prismatic, or pouch, etc.) and optionally impregnated with an electrolyte to form a secondary battery. At this time, the anode tab and the cathode tab may be connected to the anode current collector and the cathode current collector described above, respectively.

[0116] The above secondary battery may be a secondary battery using a liquid electrolyte as described above. The liquid electrolyte may be impregnated into the electrode assembly (21, 22, 23). The liquid electrolyte may include a lithium salt and a non-aqueous organic solvent. This electrolyte acts as a transport medium for lithium ions between the positive and negative electrodes, and while these lithium ions exist within the electrolyte in a solvated state, they may be inserted into the electrode active material through desolvation at the interface between the electrolyte and the electrode.

[0117] The lithium salt included in the above electrolyte is used as a medium for transferring ions within the lithium secondary battery. The lithium salt is, for example, Li as a cation + Includes, and F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - It may include anions selected from the group consisting of

[0118] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 It may include one or more selected from the group consisting of LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiFSI (Lithium bis(fluorosulfonyl) imide, LiN(SO2F)2), LiBETI (lithium bis(perfluoroethanesulfonyl) imide, LiN(SO2CF2CF3)2) and LiTFSI (lithium bis(trifluoromethanesulfonyl) imide, LiN(SO2CF3)2).

[0119] The concentration of the above lithium salt can be appropriately changed within a range that is typically usable, and may be included in the electrolyte at a concentration of 0.5 M to 6 M or 1 M to 5 M.

[0120] Meanwhile, the type of non-aqueous organic solvent that may be included in the above electrolyte is not particularly limited, and any organic solvent known to be applicable to lithium-ion battery electrolytes, etc. may be used. Examples of such organic solvents include one or more selected from the group consisting of carbonate-based solvents, ether-based solvents, nitrile-based solvents, phosphate-based solvents, and sulfone-based solvents.

[0121] More specifically, the carbonate-based solvent may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, methyl propyl carbonate, ethyl methyl carbonate, ethyl propyl carbonate, or methyl(2,2,2-trifluoroethyl) carbonate, and the phosphate-based solvent may include trimethyl phosphate, triethyl phosphate, or 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphosphorane 2-oxide.

[0122] In addition, the above ether-based solvent may be a tetrahydrofuran derivative such as dibutyl ether, tetraglame, diglame, dimethoxyethane, or 2-methyl tetrahydrofuran, and the above nitrile-based solvent may be succinonitrile, adiponitrile, sebaconitrile, acetonitrile, or propionitrile. In addition, the above sulfone-based solvent may be dimethyl sulfone, ethylmethyl sulfone, or sulforane.

[0123] Meanwhile, the aforementioned secondary battery can be manufactured according to conventional methods in the field. For example, the electrode assembly (21, 22, 23) described above can be housed in a cylindrical case, and a cylindrical secondary battery can be manufactured by injecting the liquid electrolyte described above.

[0124] The aforementioned secondary battery is not only applied to battery cells used as power sources for small devices, but is also particularly suitable for use as a unit cell in battery modules that serve as power sources for medium and large devices.

[0125] A secondary battery according to one embodiment of the present application may have a discharge capacity of 2000 mAh or more, 2500 mAh or more, or 3000 mAh or more after 50 charge-discharge cycles, or a discharge capacity retention rate of 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more.

[0126] The invention will be explained in more detail below through specific embodiments. However, the following embodiments are merely examples to aid in understanding the invention and do not limit the scope of the invention.

[0127]

[0128] Example 1.

[0129] (1) Preparation of the first electrode (101) - cathode

[0130] A mixture containing SiO₂ and graphite in a weight ratio of 15:85 was used as the negative electrode active material. Carbon nanotubes were used as the conductive material, and polyvinylidene fluoride (PVdF) was used as the binder.

[0131] The above-mentioned cathode active material, conductive material, and binder were mixed in a weight ratio of 96.5:1.5:2 and dispersed in a solvent to prepare a slurry. The prepared slurry was coated to a uniform thickness on one side of a 25 μm thick copper foil (Cu foil) using a blade-type coating machine, the Mathis Coater (Labdryer / coater type LTE, Werner Mathis AG). Subsequently, the coated slurry was dried in a vacuum oven at 110°C to 130°C for 12 to 24 hours and rolled using a roll roller machine to manufacture a cathode.

[0132] (2) Second electrode (201) manufacturing - anode

[0133] As the cathode active material, lithium nickel-cobalt-manganese composite oxide (NCM 811) containing 80 mol% nickel among the total transition metals was used. Carbon nanotubes were used as the conductive material, and polyvinylidene fluoride (PVdF) was used as the binder.

[0134] The above-mentioned positive active material, conductive material, and binder were mixed in a weight ratio of 96:2:2 and dispersed in an NMP (N-Methyl-2-pyrrolidone) solvent at 2,500 rpm to 3,000 rpm to prepare a slurry. The prepared slurry was coated to a uniform thickness on one side of a 25 μm thick aluminum foil using a blade-type coating machine, the Mathis Coater (Labdryer / coater type LTE, Werner Mathis AG). Subsequently, the coated slurry was dried in a vacuum oven at 110°C to 130°C for 12 to 24 hours and rolled using a roll press machine to manufacture a positive electrode.

[0135] (3) Insulating layer (300)

[0136] A polyethylene resin elastic foam sheet (thickness: 70 μm) manufactured by Youngbo Chemical Co., Ltd. under the product name Filmy was used as the insulation layer. Compression tests were conducted on this elastic foam sheet using the standard method of ASTM D3574 to evaluate the thickness-direction strain (Compression Force Displacement) under load. The evaluation results are shown in Fig. 9 (Horizontal axis: Strain (%), Vertical axis: Strength or Load (kgf / cm²)). 2 Figure 9 is a graph showing the results of evaluating the strain in the thickness direction according to the applied load by conducting a compression test on the polyethylene resin elastic foam sheet used as an insulating layer in Example 1 of the present application using the standard method of ASTM D3574. Referring to Figure 9, the insulating layer [shows] 1 MPa (10.197162 kgf / cm² 2 It was confirmed that it exhibits elasticity defined by a thickness direction strain of about 40% under a load.

[0137] (4) Electrode laminate (11), electrode assembly (21) and secondary battery manufacturing

[0138] As shown in FIG. 1, the first electrode (101), the insulating layer (300), and the second electrode (201) were sequentially stacked to manufacture the electrode stack (11) of Example 1.

[0139] Two or more manufactured electrode stacks (11) were stacked as shown in FIG. 6, and a porous polyethylene (PE) film, which is an ion transfer layer (400), was interposed between adjacent electrode stacks (11) among the two or more electrode stacks (11) to manufacture the electrode assembly (21) of Example 1.

[0140] The manufactured electrode assembly (21) was wound into a jelly-roll shape so that the electrode assembly (21) had the shape of a wound jelly-roll structure. After placing the electrode assembly (21) having the shape of a wound jelly-roll structure inside a cylindrical battery case, an electrolyte was injected into the case to manufacture a cylindrical secondary battery. At this time, the electrolyte was prepared by dissolving LiFSI at a concentration of 1.0 M in an organic solvent composed of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) (mixed in a volume ratio of EC:EMC = 3:7).

[0141]

[0142] Comparative Example 1: Preparation of an electrode laminate and a cylindrical secondary battery

[0143] The electrode laminate, electrode assembly, and cylindrical secondary battery of Comparative Example 1 were manufactured in the same manner as in Example 1 described above, except that the insulating layer was formed with an unfoamed polyethylene resin film (thickness: 70 μm) instead of the polyethylene resin elastic foam sheet (thickness: 70 μm) used in Example 1 above.

[0144] Compression tests were conducted on the unfoamed polyethylene resin film using the standard method of ASTM D3574 to evaluate the compression force displacement in the thickness direction according to the load. The insulating layer did not exhibit elasticity and 1 MPa (10.197162 kgf / cm²). 2It was confirmed that no deformation occurred, with the strain in the thickness direction being 0% even when a load of ) was applied.

[0145]

[0146] Experimental Example - Charge / Discharge Test

[0147] For the cylindrical secondary batteries of Example 1 and Comparative Example 1 above, charging and discharging were performed twice at room temperature (approx. 25°C) under conditions of 0.1C charging - 0.1C discharging (cut-off: 4.3V). During these charging and discharging tests, X-ray CT (X-ray Computed Tomography) images showing the top view of the jelly-roll structure-shaped electrode assembly of each cylindrical secondary battery when charged to 100% State of Charge (SOC) are shown in FIG. 10 (Example 1) and FIG. 11 (Comparative Example 1).

[0148] Referring to FIG. 10, in the cylindrical secondary battery of Example 1, it was confirmed that an insulating layer (300) satisfying a predetermined thickness direction (i.e., radial direction) strain effectively buffers the volume change of the negative electrode, so that deformation of the electrode assembly (21) and collapse of the center do not occur.

[0149] On the other hand, referring to Fig. 11, it was confirmed that in the cylindrical secondary battery of Comparative Example 1, the insulating layer failed to properly buffer the large volume change of the negative electrode due to charging, resulting in deformation of the electrode assembly itself and collapse of the center of the cylindrical secondary battery.

[0150] During the two charge-discharge test process, the change pattern of cell potential was measured for the cylindrical secondary batteries of Example 1 and Comparative Example 1, respectively, and the measurement results are shown in FIG. 12.

[0151] Referring to FIG. 12, the secondary battery of Example 1 performed two charge-discharge cycles successfully. On the other hand, it was confirmed that the secondary battery of Comparative Example 1 could not be operated further during discharge after one charge due to a large volume change of the negative electrode and deformation of the secondary battery during charging.

[0152] In addition, after two charge-discharge cycles, the charge-discharge was continued at room temperature (approx. 25°C) under the condition of 0.2C charge - 0.5C discharge (cut-off: 4.3V), and the discharge capacity per cycle was evaluated, and the evaluation results are shown in Fig. 13.

[0153] Referring to FIG. 13, the capacity of the secondary battery of Example 1 was maintained stably per cycle during continuous charging and discharging. On the other hand, it was confirmed that the secondary battery of Comparative Example 1 could not undergo continuous charging and discharging tests due to large volume changes of the negative electrode and deformation of the secondary battery during charging.

[0154] Although specific embodiments of the invention have been described in detail above, the scope of the invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the invention as defined in the following claims also fall within the scope of the invention.

Claims

1. A first electrode comprising a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; A second electrode comprising a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector; and An insulating layer comprising an elastic polymer is provided between the first electrode and the second electrode, and The first electrode material layer comprises one or more of a non-cathode coating layer, a lithium layer, and a silicon-based active material layer, and The above insulating layer has a thickness of 10 μm to 100 μm, and the electrode laminate has a thickness direction strain of 10% to 90% under a load of 1 MPa as a result of a compression test performed according to the standard method of ASTM D3574.

2. In Paragraph 1, The first electrode material layer is provided on one surface of the first electrode current collector, and The second electrode material layer is provided on one surface of the second electrode current collector, and The above insulating layer is provided between the other side of the first electrode current collector where the first electrode material layer is not provided and the other side of the second electrode current collector where the second electrode material layer is not provided, forming an electrode laminate.

3. In claim 1, the elastic polymer comprises one or more of a polyolefin-based polymer, a polyurethane-based polymer, and a silicone-based polymer, forming an electrode laminate.

4. In paragraph 3, the insulating layer is an electrode laminate in which the elastic polymer is included in the form of foam.

5. An electrode laminate according to claim 4, wherein the insulating layer further comprises an insulating polymer that does not have a foamed form.

6. An electrode laminate according to claim 4, further comprising an insulating additional layer comprising an insulating polymer and disposed between the first electrode and the second electrode.

7. In claim 6, the insulating polymer is an electrode laminate that does not have a foamed form.

8. In paragraph 6, the insulating addition layer is an electrode laminate laminated on the insulating layer.

9. Includes a plurality of stacked electrode laminates and an ion transport layer, and The above ion transport layer is provided between adjacent electrode stacks among the electrode stacks, and The electrode laminate comprises: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode including a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector, having a polarity different from that of the first electrode; and an insulating layer provided between the first electrode and the second electrode and including an elastic polymer. The above insulating layer has a thickness of 10 μm to 100 μm, and as a result of performing a compression test according to the standard method of ASTM D3574, the thickness direction strain is 10% to 90% under a load of 1 MPa, an electrode assembly.

10. A plurality of stacked electrode stacks, an intermediate electrode provided between adjacent electrode stacks among the electrode stacks, and an ion transport layer provided between the intermediate electrode and the adjacent electrode stacks. The electrode laminate comprises: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode including a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector, having the same polarity as the first electrode; and an insulating layer provided between the first electrode and the second electrode and including an elastic polymer. The above insulating layer has a thickness of 10 μm to 100 μm, and as a result of conducting a compression test using the standard method of ASTM D3574, the strain in the thickness direction is 10% to 90% under a load of 1 MPa, and The above-mentioned electrode is an electrode assembly having a polarity different from that of the first electrode and the second electrode.

11. An electrode assembly according to claim 10, wherein the above-mentioned inter-electrode comprises an inter-electrode current collector and inter-electrode material layers provided on both sides of the inter-electrode current collector.

12. Includes an electrode stack and an ion transport layer provided on the electrode stack, and The electrode laminate comprises: a first electrode including a first electrode current collector and a first electrode material layer provided on one or both sides of the first electrode current collector; a second electrode including a second electrode current collector and a second electrode material layer provided on one or both sides of the second electrode current collector, having a polarity different from that of the first electrode; and an insulating layer provided between the first electrode and the second electrode and including an elastic polymer. The above insulating layer has a thickness of 10 μm to 100 μm, and as a result of conducting a compression test using the standard method of ASTM D3574, the strain in the thickness direction is 10% to 90% under a load of 1 MPa, and The electrode laminate and the ion transport layer are wound together to form a jelly-roll structure. Electrode assembly.

13. An electrode assembly according to claim 9, 10 or 12, wherein the ion transport layer is a porous separator or a solid electrolyte layer.

14. In Paragraph 13, The above solid electrolyte layer comprises an electrode assembly including a sulfide-based solid electrolyte.

Images