Electrode, and lithium secondary battery and battery pack comprising same

Abstract

The present specification relates to an electrode, and a lithium secondary battery and a battery pack comprising same, the electrode comprising an electrode current collector layer, an electrode active material layer, and a functional layer interposed between the electrode current collector layer and the electrode active material layer, wherein the functional layer includes a specific kind of flame retardant binder and has a limiting oxygen index of 30% or more. The electrode according to the embodiment can ensure battery characteristics while preventing thermal runaway.

Description

Electrode, lithium secondary battery and battery pack including same

[0001] The present application relates to an electrode, a lithium secondary battery including the same, and a battery pack.

[0002] This application claims the benefit of Korean Patent Application Nos. 10-2023-0192121 and 10-2024-0197936, filed with the Korean Intellectual Property Office on December 27, 2023 and December 27, 2024, the entire contents of which are incorporated herein by reference.

[0003] Secondary batteries are batteries that can be reused by charging even after discharge, and can be used as an energy source for small devices such as mobile phones, tablet PCs, and vacuum cleaners, and as an energy source for medium-sized or large devices such as personal mobility, automobiles, and ESS (Energy Storage Systems) for smart grids.

[0004] In order to be utilized in such a wide range of applications, high performance is also required for secondary batteries. As a result of numerous research and development efforts, lithium secondary batteries with high energy density and ease of processing, which can be applied to various electronic devices, are attracting attention.

[0005] However, lithium secondary batteries are not only vulnerable to external shocks, but also prone to internal deterioration, leading to frequent ignition. This problem can lead to significant damage by causing heat transfer between multiple battery cells, resulting in thermal runaway in assembly units such as battery modules or battery packs connected in series and / or parallel.

[0006] Specifically, if the internal temperature of a lithium secondary battery exceeds a certain temperature, the internal pressure of the cell may increase due to the vaporization of the electrolyte, which may cause the electrolyte to be ejected from the cell or damage the separator. If the flammable gaseous substance is ignited due to the vaporization of the electrolyte or the separator is damaged, an internal short circuit may occur, which may cause an inappropriate exothermic reaction to continuously or serially occur due to the heating of adjacent cells, which may lead to ignition, and the fire may spread throughout the entire battery pack. However, since lithium ions are highly reactive to water, there is a problem that the fire may spread further even if it is attempted to be extinguished with water.

[0007] To solve the above problem, research is being conducted on materials that can early block or suppress the phenomenon of continuous or serial occurrence of inappropriate exothermic reactions in electrode units.

[0008] The present inventors have completed an electrode having the characteristics of interposing a functional layer including a flame-retardant binder having a limiting oxygen index of 30% or more between a current collector and an electrode active material layer, and limiting the flame-retardant binder to a specific type, thereby maintaining the intended battery characteristics while simultaneously blocking heat transfer and thermal runaway between cells in advance.

[0009] Specifically, the present specification seeks to provide an electrode having the above characteristics, a lithium secondary battery including the same, and a battery pack.

[0010] One embodiment of the present specification provides an electrode including an electrode current collector layer; an electrode active material layer; and a functional layer interposed between the electrode current collector layer and the electrode active material layer, wherein the functional layer includes a flame-retardant binder having a limiting oxygen index of 30% or more as measured according to ASTM D2863, and wherein the flame-retardant binder is at least one selected from a phenol resin, a novolac resin, a polyimide resin, a polybenzoxazole resin, a polybenzimidazole resin, a polybenzthiazole resin, and a halogenated aromatic resin.

[0011] Another embodiment of the present specification provides a lithium secondary battery comprising a first electrode; a second electrode; a separator interposed between the first electrode and the second electrode; and an electrolyte, wherein at least one of the first electrode and the second electrode is the electrode described above.

[0012] Another embodiment of the present specification provides a battery pack including the lithium secondary battery described above as a unit cell.

[0013] An electrode according to one embodiment of the present invention maintains characteristics such as long life and low cell resistance, while at the same time satisfying a high limiting oxygen index, and a functional layer including a flame-retardant binder of a specific range is positioned between an electrode current collector layer and an electrode active material layer, thereby making it difficult for the electrode to self-combust or combust with other elements of a battery in the future due to oxygen, thereby preventing additional thermal runaway or delaying the time required for thermal runaway. In addition, compared to a flame-retardant electrolyte, the electrode according to the present invention is cost-effective, easier to apply to a process, and effective in suppressing side reactions.

[0014] Figure 1 is a schematic diagram of an electrode according to the present invention.

[0015] Figures 2 and 3 are schematic diagrams of a lithium secondary battery according to the present invention.

[0016] Figure 4 is a schematic diagram of a battery pack according to the present invention.

[0017] Figure 5 is a schematic diagram of a moving vehicle including a battery pack according to the present invention.

[0018] 1: Electrode current collector layer

[0019] 2: Functional layer

[0020] 3: Electrode active material layer

[0021] 10: Electrode

[0022] 10-1: First electrode

[0023] 10-2: Second electrode

[0024] 11: Membrane

[0025] 20: Lithium secondary battery (cross-section)

[0026] 100: Lithium secondary battery

[0027] 201: Housing

[0028] 300: Battery Pack

[0029] 400: Means of transportation

[0030] Before explaining the present invention, some terms are first defined.

[0031] In this specification, 'p to q' may mean a range of 'p or more and q or less'.

[0032] In this specification, when a part is expressed as 'including' or 'having' a certain component, unless otherwise defined, it may mean that other components may be included rather than excluding other components.

[0033] In this specification, singular expressions include plural expressions unless otherwise defined.

[0034] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0035] Hereinafter, the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily practice it. However, the present invention can be implemented in various different forms and is not limited to the following description.

[0036] Electrode

[0037] Hereinafter, the electrode (10) will be described with reference to Fig. 1.

[0038] An electrode according to one embodiment of the present specification includes a functional layer interposed between an electrode current collector layer and an electrode active material layer, wherein the functional layer includes a flame-retardant binder having a limiting oxygen index of 30% or more as measured according to ASTM D2863, and the flame-retardant binder is characterized in that it is at least one selected from a phenol resin, a novolac resin, a polyimide resin, a polybenzoxazole resin, a polybenzimidazole resin, a polybenzthiazole resin, and a halogenated aromatic resin.

[0039] FIG. 1 illustrates an electrode (10) in an embodiment according to the present invention, and it can be seen that a functional layer (2) including a specific type of flame-retardant binder having a limit oxygen index of 30% or more is provided between an electrode current collector layer (1) and an electrode active material layer (3).

[0040] In this specification, the limiting oxygen index is the minimum oxygen volume fraction (%) required to sustain combustion, which can be calculated by the following equation 1.

[0041] [Formula 1]

[0042]

[0043] In addition, when measuring LOI according to the ASTM D2863 method, the measurement target (flame retardant binder) is Test specimen type IV (70 X 6.5 X 3 mm 3 ) can be used to produce a sample.

[0044] The functional layer (2) has a high limiting oxygen index and includes a flame-retardant binder of a specific range, and due to the low combustibility of the flame-retardant binder, it is difficult for the electrode to self-combust or combust with other elements of the battery in the future by oxygen, thereby preventing further thermal runaway or delaying the time required for thermal runaway.

[0045] As described above, when the limiting oxygen index is 30% or more and a specific type of flame-retardant binder is used, combustion becomes difficult to occur due to the flame retardancy of the functional layer when the electrode ignites, and heat transfer to the electrode current collector layer is suppressed, thereby delaying melting or combustion of the electrode current collector layer and delaying the time required for thermal runaway.

[0046] According to one embodiment of the present specification, the thickness of the electrode current collector layer may be 3 ㎛ or more and 30 ㎛ or less.

[0047] Depending on the type of the electrode current collector layer, the thickness of the electrode current collector layer can be adjusted, and the thickness of the negative electrode current collector layer using a material such as copper may be preferably changed to 5 ㎛ or more or 6 ㎛ or more and 25 ㎛ or less or 20 ㎛ or less, and the thickness of the positive electrode current collector layer using a material such as aluminum may be preferably changed to 7 ㎛ or more or 8 ㎛ or more and 25 ㎛ or less or 20 ㎛ or less.

[0048] According to one embodiment of the present specification, the thickness of the entire electrode may be 30 ㎛ or more and 200 ㎛ or less.

[0049] Depending on the type of electrode, the thickness of the entire electrode may be adjusted. For example, in the case of the cathode, the thickness may preferably be changed to 40 ㎛ or more or 50 ㎛ or more and 170 ㎛ or less or 150 ㎛ or less, and in the case of the anode, the thickness may preferably be changed to 40 ㎛ or more or 50 ㎛ or more and 120 ㎛ or less or 100 ㎛ or less.

[0050] According to one embodiment of the present specification, the thickness of the functional layer may be 0.1 ㎛ or more and 10 ㎛ or less.

[0051] When the above thickness range is satisfied, the flame retardancy expression is maximized while minimizing the increase in the thickness of the electrode due to the functional layer, so the intended thermal runaway prevention effect can be obtained.

[0052] The upper limit of the thickness of the functional layer can be adjusted according to the needs such as conductivity and heat dissipation characteristics, and preferably can be changed to 5 ㎛ or less, 4 ㎛ or less, or 3 ㎛ or less.

[0053] According to one embodiment of the present specification, the functional layer may further include a flame retardant.

[0054] According to one embodiment of the present specification, the functional layer may include a flame retardant binder in an amount of more than 0 parts by weight and less than or equal to 50 parts by weight based on 100 parts by weight of the total slurry included in the functional layer.

[0055] When the above flame retardant binder satisfies the above content range, it is excellent in terms of preventing thermal runaway.

[0056] According to one embodiment of the present specification, the functional layer may include a conductive material in an amount of 0.1 to 90 parts by weight based on 100 parts by weight of the total slurry included in the functional layer.

[0057] As long as the conductive material satisfies the above content range, it is excellent in terms of electrical conductivity within the electrode. However, in order to further improve conductivity, in some cases, the conductive material may be included in an amount of 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, or 50 parts by weight or more, and 85 parts by weight or less, or 80 parts by weight or less, based on 100 parts by weight of the total slurry included in the functional layer.

[0058] In this specification, the slurry included in the functional layer may mean a mixture of a flame retardant binder and a solvent for forming the functional layer.

[0059] In this specification, the solvent for forming the functional layer may be N-methyl-2-pyrrolidone (NMP), water, etc., but is not limited thereto.

[0060] According to one embodiment of the present specification, the functional layer may include a flame retardant binder in an amount of 1 part by weight or more and 99 parts by weight or less based on 100 parts by weight of the total slurry included in the functional layer.

[0061] As long as the flame retardant binder satisfies the above content range, the thermal runaway problem can be improved; however, in order to further prevent thermal runaway, in some cases, the flame retardant binder may be included in an amount of 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more, and 90 parts by weight or less, 70 parts by weight or less, or 50 parts by weight or less, based on 100 parts by weight of the total slurry included in the functional layer.

[0062] According to one embodiment of the present specification, the functional layer may include a conductive material of 0.1 to 90 parts by weight; and a flame retardant binder of 1 to 99 parts by weight.

[0063] According to one embodiment of the present specification, the flame retardant may include an inorganic flame retardant, an organic flame retardant, or a combination thereof.

[0064] In this specification, the inorganic flame retardant may be selected from a silicone-based flame retardant, an aluminum-based flame retardant, a molybdenum-based flame retardant, etc., but any flame retardant known in the art may be used as long as it does not depart from the scope of the present invention.

[0065] In this specification, the organic flame retardant may be selected from carbon-based flame retardants, halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, etc., but any flame retardant known in the art may be used as long as it does not depart from the scope of the present invention.

[0066] According to one embodiment of the present specification, the conductive material may be at least one of a planar conductive material, a linear conductive material, and a dot-shaped conductive material.

[0067] In this specification, the planar conductive material serves to improve conductivity by increasing planar contact with other elements within the functional layer, and may be expressed as a plate-shaped or bulk-shaped conductive material. Examples of the planar conductive material in terms of the functional layer include graphene, graphene oxide, and the like, but graphene is preferred.

[0068] In the present specification, the linear conductive material may be a carbon nanotube. The carbon nanotube may be a bundle-type carbon nanotube. The bundle-type carbon nanotube may include a plurality of carbon nanotube units. Specifically, the term "bundle type" herein refers to a secondary shape in the form of a bundle or rope in which a plurality of carbon nanotube units are arranged in a substantially identical orientation in a longitudinal direction of the carbon nanotube units or are entangled. The carbon nanotube unit has a graphite sheet in the form of a cylinder with a nano-sized diameter, and sp 2 It has a bonding structure. At this time, depending on the angle and structure at which the graphite plane is rolled, it can exhibit the characteristics of a conductor or semiconductor. The bundle-type carbon nanotubes can be uniformly distributed compared to entangled type carbon nanotubes, and can smoothly form a conductive network within the functional layer, thereby further improving conductivity.

[0069] In the present specification, the dot-shaped conductive material may be selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, potassium titanate, titanium oxide, polyphenylene derivatives, etc., but as long as it does not depart from the scope of the present invention, those known in the art may be used.

[0070] According to one embodiment of the present specification, the flame retardant binder may include a polymer including an aromatic hydrocarbon ring, a heterocycle, a halogen-substituted polymer, etc. Alternatively, the flame retardant binder may be at least one selected from the group consisting of a phenol resin, a novolac resin, a polyimide resin, a polybenzoxazole (PBO) resin, a polybenzimidazole resin, a polybenzthiazole (PBT) resin, a halogenated resin, etc.

[0071] The functional layer including the above flame retardant binder can further prevent thermal runaway.

[0072] According to one embodiment of the present specification, the vertical resistance of the functional layer may be 0.5 Ω or less. When the vertical resistance of the functional layer satisfies the upper limit, the problem of conductive connectivity due to the introduction of the functional layer can be prevented and it is excellent in terms of electrical conductivity. The lower limit of the vertical resistance of the functional layer is not particularly limited as long as it is 0 Ω, but it is preferably at least 0.1 Ω or more in order for the functional layer to maintain the intended conductivity between the electrode current collector layer and the electrode active material layer.

[0073] In this specification, vertical resistance means a resistance value Ω measured in the vertical direction by positioning a conductive load (e.g., a metal circular block plated with Au on a Cu metal surface) below and above the target material, and the influence of the thickness on the functional layer is not large, but preferably, the same level of vertical resistance can be exhibited at a thickness of 0.1 ㎛ or more and 10 ㎛ or less.

[0074] According to one embodiment of the present specification, the functional layer may further include a heat-dissipating filler.

[0075] In this specification, the heat-dissipating filler may be selected from graphene, expandable graphite, etc., but any known material in the art may be used as long as it does not depart from the scope of the present invention.

[0076] According to one embodiment of the present specification, the functional layer may further include graphene.

[0077] In this specification, the graphene is included as a flame retardant, conductive material and / or heat dissipating filler.

[0078] According to one embodiment of the present specification, the functional layer may further include SWCNTs (in addition to graphene).

[0079] In this specification, the SWCNT is included as a conductive material.

[0080] Lithium secondary battery

[0081] Hereinafter, the lithium secondary batteries of FIGS. 2 and 3 will be described.

[0082] According to one embodiment of the present specification, a lithium secondary battery comprising a first electrode; a second electrode; a separator interposed therebetween; and an electrolyte, wherein either one of the first electrode and the second electrode is the electrode described above.

[0083] The lithium secondary battery of the above embodiment includes the electrode described above, and thus, components of the lithium secondary battery and factors that may cause thermal runaway can be blocked in advance.

[0084] Referring to Fig. 2, a separator (11) is interposed between a first electrode (10-1) and a second electrode (10-2), and at least one of the first electrode (10-1) and the second electrode (10-2) may be the above-described electrode. Specifically, referring to Fig. 3, one side of the separator (11) is in contact with one side of the electrode active material layer (3), one side of the functional layer (2) is in contact with the opposite side of the side of the electrode active material layer (3) that is in contact with the separator (11), and an electrode current collector layer (1) may be provided on the opposite side of the side of the functional layer (2) that is in contact with the electrode active material layer (3).

[0085] In this specification, the first electrode may be a cathode and the second electrode may be an anode, or the first electrode may be an anode and the second electrode may be a cathode.

[0086] Accordingly, when the above-described electrode is a negative electrode, the above-described electrode current collector layer may be referred to as a negative electrode current collector layer, and the above-described electrode active material layer may be referred to as a negative electrode active material layer. The specific details are as follows.

[0087] In this specification, the negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used.

[0088] In this specification, the negative electrode current collector may generally have a thickness of 1 μm to 100 μm, and may have fine unevenness formed on the surface of the current collector to increase the adhesive strength of the negative electrode active material. In addition, the negative electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0089] In one embodiment of the present specification, the negative electrode active material layer may include at least one of a silicon-based active material and a carbon-based active material.

[0090] In one embodiment of the present specification, the negative electrode active material layer may include a carbon-based active material.

[0091] The above carbon-based active material can prevent expansion due to repeated charging and discharging in the negative electrode or lithium secondary battery of the present invention, thereby contributing to excellent cycle characteristics or improved battery life performance.

[0092] In one embodiment of the present specification, the negative electrode active material layer may include a silicon-based active material.

[0093] In general, silicon-based active materials are known to have a capacity more than 10 times higher than carbon-based active materials. Therefore, applying silicon-based active materials to the cathode can create an electrode with a high energy density even with a thin thickness.

[0094] In one embodiment of the present specification, the silicon-based active material is SiOx (x=0), SiOx (0 <x<2), Si / C 복합재 및 Si 합금으로 이루어진 군에서 선택되는 1 이상을 포함할 수 있다.

[0095] Meanwhile, since SiO2 does not react with lithium ions and thus cannot store lithium, it is preferable that x be within the above range. The silicon-based active material may be a Si / C composite composed of a composite of Si and C or Si.

[0096] Depending on the need, the above silicon-based active material may refer to one type of single material or a mixed material of two or more types.

[0097] In one embodiment of the present specification, the silicon-based active material is SiOx (x=0) and SiOx (0 <x<2)로 이루어진 군에서 선택되는 1 이상을 포함하며, 상기 실리콘계 활물질 100 중량부 기준 상기 SiOx (x=0)를 70 중량부 이상 포함하는 것인 음극 조성물을 제공한다.

[0098] In one embodiment of the present specification, the silicon-based active material may contain SiOx (x=0) in an amount of 70 parts by weight or more, preferably 80 parts by weight or more, more preferably 90 parts by weight or more, and may contain 100 parts by weight or less, preferably 99 parts by weight or less, more preferably 95 parts by weight or less, based on 100 parts by weight of the silicon-based active material.

[0099] The silicon-based active material according to this specification contains 70 parts by weight or more of SiOx (x=0) based on 100 parts by weight of the silicon-based active material, and SiOx(0 <x<2) 계열을 주된 물질로 사용하는 실리콘계 활물질과 대비할 때, 이론적 용량이 본 명세서의 실리콘계 활물질에 비하여 훨씬 높게 구현될 수 있다.

[0100] In one embodiment of the present specification, the silicon-based active material may be pure silicon (Si). Using pure silicon (Si) as the silicon-based active material may mean that, based on 100 parts by weight of the total silicon-based active material, pure Si particles (SiOx (x=0)) that are not combined with other particles or elements are included within the above range.

[0101] In one embodiment of the present specification, the negative electrode active material layer may further include a negative electrode conductive material and a negative electrode binder.

[0102] The above negative electrode conductive material is used to provide conductivity to the electrode, and can be used without any special restrictions as long as it does not cause chemical changes in the battery and has electronic conductivity. However, the negative electrode conductive material is applied to the negative electrode and has a completely separate composition from the positive electrode conductive material applied to the positive electrode. That is, the negative electrode conductive material plays a role in securing the contact between silicon-based active materials, which undergo a large volume expansion of the electrode due to charging and discharging, whereas the positive electrode conductive material acts as a buffer when rolled and provides some conductivity, so the negative electrode conductive material and the positive electrode conductive material have different compositions and roles.

[0103] Specific examples of the above negative conductive material may include at least one selected from the group consisting of point-shaped conductive materials, planar conductive materials, and linear conductive materials.

[0104] Specifically, the dot-shaped conductive material may be at least one selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, conductive fiber, fluorocarbon, aluminum powder, nickel powder, zinc oxide, potassium titanate, titanium oxide, and polyphenylene derivatives, and preferably may include carbon black and / or artificial graphite in terms of implementing high conductivity and excellent dispersibility.

[0105] The above-mentioned planar conductive material can improve conductivity by increasing planar contact between silicon particles within the cathode, and at the same time, suppress the disconnection of the conductive path due to volume expansion. The above-mentioned planar conductive material can be expressed as a plate-shaped conductive material or a bulk conductive material. An example of the above-mentioned planar conductive material may include at least one selected from the group consisting of plate-shaped graphite, graphene, graphene oxide, and graphite flakes, and preferably plate-shaped graphite.

[0106] The linear conductive material may be a carbon nanotube. The carbon nanotube may be a bundle-type carbon nanotube. The bundle-type carbon nanotube may include a plurality of carbon nanotube units. Specifically, the term "bundle type" herein refers to a secondary shape in the form of a bundle or rope in which a plurality of carbon nanotube units are arranged in a substantially identical orientation in a longitudinal direction of the carbon nanotube units or are entangled. The carbon nanotube unit has a graphite sheet having a cylindrical shape with a nano-sized diameter, and sp 2 It has a bonding structure. At this time, depending on the angle and structure at which the graphite plane is rolled, it can exhibit the characteristics of a conductor or semiconductor. Compared to entangled type carbon nanotubes, the bundled carbon nanotubes can be uniformly dispersed during the manufacture of the cathode, and can smoothly form a conductive network within the cathode, thereby improving the conductivity of the cathode.

[0107] In one embodiment of the present specification, a negative electrode composition is provided in which the negative electrode conductive material is present in an amount of 0.1 parts by weight or more and 40 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0108] In another embodiment, the negative electrode conductive material may be included in an amount of 0.1 to 40 parts by weight, preferably 0.2 to 30 parts by weight, more preferably 0.4 to 25 parts by weight, and most preferably 0.4 to 10 parts by weight, based on 100 parts by weight of the negative electrode composition.

[0109] The above-mentioned negative electrode binder serves to improve the adhesion between negative electrode active material particles and the adhesive strength between the negative electrode active material and the negative electrode current collector, and can be divided into aqueous binders and non-aqueous binders (organic binders) depending on whether it dissolves well in an aqueous solvent such as water. Specific examples of the above-mentioned negative electrode binder include carboxymethyl cellulose (CMC)-based binders, styrene butadiene rubber (SBR)-based binders, polyacrylic acid (PAA)-based binders, polyacrylamide (PAM)-based binders, polyacrylonitrile (PAN)-based binders, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), etc., various copolymers derived therefrom, or a mixture of two or more selected therefrom.

[0110] In one embodiment of the present specification, a negative electrode composition is provided in which the weight average molecular weight of the negative electrode binder is 100,000 g / mol or more and 1,000,000 g / mol or less.

[0111] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are polystyrene-equivalent molecular weights measured by gel permeation chromatography (GPC) using monodisperse polystyrene polymers (standard samples) of various degrees of polymerization commercially available for molecular weight measurement as standard materials. In this specification, unless otherwise specified, molecular weight means weight average molecular weight.

[0112] By satisfying the above weight-average molecular weight range, the electrode exhibits excellent mechanical strength and high intermolecular interaction, resulting in superior electrode adhesion. Furthermore, satisfying the above range allows for the binder's viscosity to be appropriately selected, resulting in superior electrode coating properties when used to manufacture a cathode.

[0113] In one embodiment of the present specification, the negative electrode binder is provided in an amount of 1 part by weight or more and 20 parts by weight or less based on 100 parts by weight of the negative electrode composition.

[0114] In one embodiment of the present specification, the negative electrode binder may be included in an amount of 20 parts by weight or less, preferably 15 parts by weight or less, based on 100 parts by weight of the negative electrode composition, and may be 1 part by weight or more, 5 parts by weight or more, or 10 parts by weight or more.

[0115] As described above, when including a negative electrode active material, a negative electrode conductive material, and a negative electrode binder, it may be referred to as a negative electrode composition.

[0116] In some cases, a solvent may be added to the cathode composition, which may be referred to as a cathode slurry. The solvent used herein may be referred to as a solvent for forming a cathode slurry.

[0117] The solvent for forming the above cathode slurry may include, but is not limited to, N-methyl-2-pyrrolidone (NMP), water, etc.

[0118] In this specification, the negative electrode means an electrode that has undergone a series of electrode processes, including a coating step of applying negative electrode slurry to at least one surface of a negative electrode collector, a pressing step of compressing to a certain thickness by roll pressing, and a slitting step of cutting to fit the electrode specifications.

[0119] In one embodiment of the present specification, the negative electrode can form a negative electrode for a lithium secondary battery by coating a negative electrode slurry containing the negative electrode composition on one side or both sides of a current collector.

[0120] In one embodiment of the present specification, the solid content of the cathode slurry can satisfy 5% or more and 40% or less.

[0121] In another embodiment, the solid content of the cathode slurry can satisfy a range of 5% or more and 40% or less, preferably 7% or more and 35% or less, and more preferably 10% or more and 30% or less.

[0122] The solid content of the above cathode slurry may mean the content of the cathode composition included in the cathode slurry, and may mean the content of the cathode composition based on 100 parts by weight of the cathode slurry.

[0123] When the solid content of the above-mentioned negative electrode slurry satisfies the above range, the viscosity is appropriate when forming the negative electrode active material layer, thereby minimizing particle agglomeration of the negative electrode composition, and thus has the characteristic of efficiently forming the negative electrode active material layer.

[0124] Other details regarding the above cathode are applied according to information known in the art.

[0125] Accordingly, when the above-described electrode is a positive electrode, the above-described electrode current collector layer may be referred to as a positive electrode current collector layer, and the above-described electrode active material layer may be referred to as a positive electrode active material layer. The specific details are as follows.

[0126] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 1 ㎛ to 500 ㎛, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0127] In one embodiment of the present specification, the thickness of the positive electrode current collector layer may be 1 µm or more and 100 µm or less, and the thickness of the positive electrode active material layer may be 20 µm or more and 500 µm or less. However, the thickness may be modified in various ways depending on the type and purpose of the positive electrode used and is not limited thereto.

[0128] The above positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4, etc., in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion, but is not limited thereto. The positive electrode may be Li-metal.

[0129] The above-described positive electrode active material layer may include a positive electrode conductive material and a positive electrode binder together with the positive electrode active material described above. When the positive electrode active material, positive electrode conductive material and positive electrode binder are included, it is referred to as a positive electrode composition, and when the positive electrode composition further includes a solvent for forming a positive electrode slurry, it may be referred to as a positive electrode slurry.

[0130] The above-mentioned positive electrode conductive material is used to provide conductivity to the electrode, and in the battery to be formed, any material that does not cause a chemical change and has electronic conductivity can be used without special restrictions. Specific examples include 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, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used.

[0131] The above-described positive electrode binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode current collector. Specific examples of the positive electrode binder include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, etc., various copolymers derived therefrom, or a mixture of two or more selected therefrom may be used.

[0132] When the above solvent refers to a solvent for forming a positive electrode slurry, N-methyl-2-pyrrolidone (NMP), water, etc. may be used, but are not limited thereto.

[0133] In this specification, the positive electrode means an electrode that has undergone a series of electrode processes, including a coating step of applying a positive electrode composition to at least one surface of a positive electrode current collector, a pressing step of compressing to a certain thickness by roll pressing, and a slitting step of cutting to fit the electrode specifications.

[0134] Other details regarding the above polarity are applied according to information known in the art.

[0135] In this specification, the electrolyte refers to a material that can be used in the manufacture of a lithium secondary battery, and may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc.

[0136] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0137] Specific examples of the above non-aqueous organic solvent include aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, dioxolan derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyrropionate, and ethyl propionate.

[0138] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants and thus can be preferably used because they easily dissociate lithium salts. In addition, when low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed and used in an appropriate ratio with these cyclic carbonates, an electrolyte with high electrical conductivity can be produced, so that they can be used even more preferably.

[0139] The metal salt may be a lithium salt, and the lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte, for example, the anion of the lithium salt is F - , Cl - , 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 - One or more selected from the group consisting of may be used.

[0140] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as, for example, a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, a cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery.

[0141] In this specification, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without any particular restrictions. In particular, the separator preferably has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0142] In this specification, a lithium secondary battery may be a concept including an electrode assembly including a positive electrode, a negative electrode, and a separator, and a battery can containing an electrolyte.

[0143] Battery Pack

[0144] The battery pack of this specification refers to Fig. 4.

[0145] One embodiment of the present specification provides a battery module and / or battery pack (300) including the lithium secondary battery (200) as a unit cell.

[0146] Since the above battery module and / or battery pack includes the lithium secondary battery (200), the contents of the above-described lithium secondary battery can be applied as is.

[0147] In this specification, the battery pack (300) may have a structure in which a lithium secondary battery (200) is included in a pack housing (201). However, the lithium secondary battery (200) may be replaced with a coin-shaped, pouch-shaped, square-shaped, etc., as well as the illustrated cylindrical shape, as needed.

[0148] In some cases, the battery pack of the present specification may include one or more battery module units.

[0149] According to FIG. 5, the battery pack (300) can be used as a power source for a medium- to large-sized device selected from the group consisting of a means of transportation (400) such as an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and an electric power storage system (EES), as needed.

[0150] Hereinafter, preferred embodiments are presented to help understand the present invention, but the above embodiments are only illustrative of the present disclosure, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present disclosure, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

[0151] Example. Manufacturing of lithium secondary batteries

[0152] Example 1

[0153] (1) Manufacturing of a cathode with a functional layer

[0154] A functional layer (thickness: 3 μm) was positioned on both sides of a negative electrode current collector (copper (Cu) thin film, thickness: 8 μm). Here, the functional layer was prepared by preparing SWCNT and SFG6L as conductive materials and polybenzimidazole as a flame-retardant binder in a weight ratio of 2:70:28, and dispersing the slurry in a solvent (N-methyl-2-pyrrolidone, NMP (solvent for forming the functional layer)), which was applied and dried on the negative electrode current collector to form a functional layer on one side of the negative electrode current collector.

[0155] Then, the negative electrode slurry was applied to the opposite side of the surface of the negative electrode current collector that is in contact with the functional layer and the opposite side of the surface of the functional layer that is in contact with the negative electrode current collector at a concentration of 3.75 mAh / cm. 2 The negative electrode was manufactured by coating with a loading amount of , drying in a vacuum oven at 130°C for 10 hours, and then rolling (roll pressing).

[0156] Specifically, the negative electrode slurry was prepared as follows. Griphite and Si / C (average particle size (D)) were used as negative electrode active materials. 50 ) 8 ㎛), the first and second conductive materials and polyacrylamide and SBB (styrene butadiene rubber) as binders were prepared in a weight ratio of 80:13:1.6:0.4:2.5:2.5 and added to a solvent (distilled water) to prepare a negative electrode slurry (solid concentration 35 wt%). Here, the first conductive material was plate-shaped graphite (specific surface area 17 m 2 / g, average particle size (D 50 ): 3.5 ㎛), and the second conductive material was a single-walled carbon nanotube (SWCNT). As a mixing method, the first conductive material, the second conductive material, the binder, and water were dispersed at 2,500 rpm for 30 minutes using a HOMO MIXER (PRIMIX), and then the negative electrode active material was added and dispersed at 2,500 rpm for 30 minutes to prepare a negative electrode slurry.

[0157] (2) Manufacturing of the anode

[0158] Cathode active material (LiN) 6.1 Co0.8 Mn 3.1 O2), anode conductive material (multi-walled carbon nanotube, MWCNT) and binder (PVdF, KF9700) were added to a solvent (N-methyl-2-pyrrolidone, NMP) at a weight ratio of 97.4:1.1:1.5 to prepare a cathode slurry (solid concentration 67 wt%). The cathode slurry was prepared at a solid concentration of 3.6 mAh / cm 2 After coating and drying the positive electrode current collector (aluminum (Al) thin film, thickness: 12 ㎛) with a loading amount (same as the manufacturing method of the negative electrode above), a positive electrode was manufactured by rolling with a roll press to form a positive electrode active material layer on the positive electrode current collector.

[0159] (3) Manufacturing of lithium secondary batteries

[0160] An electrode assembly was manufactured by interposing a compressible thin film separator (PE 15 ㎛) Ceramic coating 4 ㎛ / 4 ㎛ between the negative electrode and the positive electrode. After positioning the electrode assembly inside a battery case, an electrolyte (an electrolyte in which 1 M LiPF6 is dissolved in a mixed solution of ethyl carbonate (EC): methyl ethyl carbonate (EMC) = 50:50 (volume ratio)) was injected into the case to manufacture a lithium secondary battery.

[0161] Example 2

[0162] A lithium-ion battery was manufactured in the same manner as in Example 1, except that the functional layer provided on the negative electrode collector was provided on the positive electrode collector.

[0163] Example 3

[0164] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the content of other components (i.e., conductive material) included in the slurry was proportionally reduced by additionally using 15 parts by weight of fluorophosphazine as a flame retardant.

[0165] Example 4

[0166] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the functional layer was made by using SWCNT and Graphene as conductive materials and preparing polybenzimidazole as a flame-retardant binder at a weight ratio of 2:75:23 to manufacture a slurry.

[0167] Comparative Example 1

[0168] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the functional layer provided on the negative electrode collector was excluded.

[0169] Comparative Example 2

[0170] A lithium secondary battery was manufactured in the same manner as in Example 1, except that PAA (poly(meth)acrylic acid) was used instead of polybenzimidazole as a flame-retardant binder when manufacturing a functional layer provided on a negative electrode current collector.

[0171] Comparative Example 3

[0172] A lithium secondary battery was manufactured in the same manner as in Example 1, except that polyvinyl alcohol was included as a flame-retardant binder when manufacturing a functional layer provided on a negative electrode current collector, and SWCNT and graphene and polyvinyl alcohol were dispersed in water at a weight ratio of 2:70:28 as a conductive material.

[0173] Comparative Example 4.

[0174] A lithium secondary battery was manufactured in the same manner as in Example 1, except that a flame-retardant binder containing PTFE (polytetrafluoroethylene) was used instead of polybenzimidazole when manufacturing a functional layer provided on a negative electrode current collector.

[0175] Reference Example 1

[0176] A lithium secondary battery was manufactured in the same manner as in Example 1, except that SWCNT was not included as a conductive material when manufacturing the functional layer provided on the negative electrode collector.

[0177] Experimental example.

[0178] Experimental Example 1: Measurement of the Limiting Oxygen Index (LOI)

[0179] The limiting oxygen index was measured for the flame-retardant binder included in each of the functional layers of Examples 1 and 3 and Comparative Examples 2 to 4. The limiting oxygen index was measured using an oxygen index meter (LOI-404 (Korea Industrial Laboratory Equipment)) according to the ASTM D2863 method, and the evaluation results of the limiting oxygen index are as shown in Table 1 below.

[0180] No. LOI(%)Example 142Example 351Comparative Example 217Comparative Example 324Comparative Example 495

[0181] According to Table 1 above, Examples 1, 3, and Comparative Example 4 have functional layers containing polybenzimidazole or PTFE as flame-retardant binders and have LOIs of 42%, 51%, and 95%, respectively, exceeding 30%, whereas Comparative Examples 2 and 3 have functional layers containing PAA and PVA as flame-retardant binders, respectively, but have LOIs of 17% and 24%, respectively, falling below 30%.

[0182] Experimental Example 2: Vertical Resistance Measurement

[0183] A 2.6 cm diameter Au-plated Cu circular metal plate was brought into contact with the electrodes (cathode or anode) of Examples 1 to 4, Comparative Examples 1 to 4, and Reference Example 1, and the electrode resistance in the vertical direction was measured three times, and the average value was taken as the vertical resistance. The evaluation results of the vertical resistance are shown in Table 2 below.

[0184] No. Vertical resistance (Ω) Example 10.08 Example 20.09 Example 30.10 Example 40.08 Comparative Example 10.075 Comparative Example 20.12 Comparative Example 30.10 Comparative Example 40.45 Reference Example 10.95

[0185] According to Table 2 above, Examples 1 to 4 and Comparative Examples 1 to 4 all showed vertical resistances of the functional layer of 0.5 Ω or less, but in the case of Reference Example 1, which does not include a conductive material such as SWCNT in the functional layer, the vertical resistance was 0.95 Ω, exceeding 0.5 Ω, and thus it was confirmed that it was unsuitable as a functional layer positioned between the electrode active material layer and the electrode current collector. Here, Examples 1 to 4 showed vertical resistances of 0.1 Ω or less, and Comparative Examples 2 to 4 showed vertical resistances of 0.1 Ω or more, so there was a difference.

[0186] Experimental Example 3: Stability Test

[0187] A heat pad was placed on one side of the cell of the lithium secondary batteries of Examples 1 to 4, Comparative Examples 1 to 4, and Reference Example 1, and the temperature of the heat pad was increased until the cell exploded. At this time, the explosion pressure was measured using an autoclave device.

[0188] The reaction time is a value obtained from the test results of the autoclave equipment, and the definition of the reaction time is the pressure rise point (TR) at thermal runaway as shown in Equation 2 below. initial ) from the point of maximum pressure reached (TR max ) means the time until.

[0189] [Formula 2]

[0190]

[0191] In addition, the TR rate is a value normalized to the cell capacity by the cell explosion rate during thermal runaway using the reaction time value derived from the above equation 2. This value is also calculated as a test result of the autoclave equipment, and the unit is mbar / (sec*mAh). The evaluation results are as follows in Table 3.

[0192] No.TR rate(mbar / (sec*mAh))Example 14.2Example 24.3Example 33.7Example 44.0Comparative Example 15.9Comparative Example 25.5Comparative Example 35.3Comparative Example 44.1Reference Example 14.6

[0193] According to Table 3 above, the TR rates of Examples 1 to 4 and Comparative Example 4 were lower than the TR rate values ​​of Comparative Examples 1 to 3 and Reference Example 1, at a maximum of 4.3 mbar / (sec*mAh). This result suggests that even for lithium secondary batteries with the same capacity, the lithium secondary batteries of Examples 1 to 4 and Comparative Example 4 have a lower cell explosion rate than those of Comparative Examples 1 to 3 and Reference Example 1, and thus have improved stability.

[0194] Experimental Example 4: Capacity Retention Rate and Lifetime Characteristics

[0195] The lifespan of the lithium secondary batteries of Examples 1 to 4, Comparative Examples 1 to 4, and Reference Example 1 was evaluated using an electrochemical charger / discharger, and the capacity retention rate was evaluated.

[0196] A lithium secondary battery was subjected to an in-situ cycle test at 4.2-3.0 V 1C / 0.5C, and a 0.33C / 0.33C charge / discharge (4.2-3.0 V) was performed every 50 cycles during the test to calculate the lifespan maintenance rate according to Equation 3 below (where N is 100). The evaluation results are shown in Table 4 below.

[0197] [Formula 3]

[0198]

[0199] Lifespan maintenance rate (%) after No.100 cycles Example 181 Example 283 Example 380 Example 480 Comparative Example 182 Comparative Example 275 Comparative Example 371 Comparative Example 454 Reference Example 132

[0200] According to Table 4 above, Examples 1 to 4 and Comparative Example 1 showed a life maintenance rate of 80% or more, suggesting that the lithium secondary batteries with functional layers (Examples 1 to 4) have no difference in life maintenance rate from the lithium secondary batteries without functional layers (Comparative Example 1). However, even with the functional layer, the lithium secondary batteries of Comparative Examples 2 and 3, which have an LOI of less than 30%, showed life maintenance rates of 75% and 71%, respectively, indicating that the complex interrelationship between the functional layer and the electrode current collector layer or electrode active material layer affects the reduction in life maintenance rate. In addition, in the case of Comparative Example 4, although the LOI was high at 95%, the cell resistance was inferior at over 0.1 Ω due to poor dispersion and coatability, and it was confirmed that the life maintenance rate was also poor.

[0201] Furthermore, the lithium secondary battery of Reference Example 1, which does not have a conductive material such as SWCNT even with a functional layer, showed the lowest lifespan retention rate of 32%. This suggests that the functional layer must have conductivity when introduced between the electrode active material layer and the electrode current collector layer.

Claims

1. An electrode current collector layer; an electrode active material layer; and a functional layer interposed between the electrode current collector layer and the electrode active material layer, The above functional layer comprises a flame retardant binder having a Limiting Oxygen Index of 30% or more as measured according to ASTM D2863. An electrode wherein the above flame retardant binder is at least one selected from a phenol resin, a novolac resin, a polyimide resin, a polybenzoxazole resin, a polybenzimidazole resin, a polybenzthiazole resin, and a halogenated aromatic resin.

2. In claim 1, An electrode wherein the thickness of the functional layer is 0.1 ㎛ or more and 10 ㎛ or less.

3. In claim 1, An electrode wherein the functional layer further contains a flame retardant.

4. In claim 1, An electrode wherein the functional layer further includes a conductive material.

5. In claim 1, An electrode wherein the functional layer comprises a conductive material of 0.1 to 90 parts by weight; and a flame retardant binder of 1 to 99 parts by weight.

6. In claim 3, An electrode wherein the flame retardant comprises at least one of an inorganic flame retardant and an organic flame retardant.

7. In claim 4, An electrode wherein the above-mentioned conductive material is at least one of a planar conductive material, a linear conductive material, and a dot-shaped conductive material.

8. In claim 1, An electrode wherein the functional layer further includes a heat-dissipating filler.

9. In claim 1, An electrode wherein the functional layer further comprises graphene.

10. In claim 9, An electrode wherein the functional layer further comprises single-walled carbon nanotubes (SWCNTs).

11. In claim 1, An electrode having a vertical resistance of the above functional layer of 0.5 Ω or less.

12. First electrode; Second electrode; A separator interposed between the first electrode and the second electrode; and Contains electrolyte, A lithium secondary battery, wherein at least one of the first electrode and the second electrode is an electrode according to any one of claims 1 to 11.

13. A battery pack comprising a lithium secondary battery according to claim 12 as a unit cell.

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