Electrode current collector and lithium secondary battery containing the same

Abstract

The electrode current collector according to the present invention includes a resin layer, a first metal layer disposed on one surface of the resin layer, and a second metal layer disposed on the other surface of the resin layer, wherein the first metal layer and the second metal layer each independently have a thickness of 3.0 μm or less, the resin layer contains a metal oxide, and the ratio (R) of the thickness of the resin layer to the first metal layer or the second metal layer is 1 to 24. This can greatly contribute to improving the safety of batteries, and despite having a structure in which the resin layer is interposed between metal layers, it has the advantage of being able to reduce electrical resistivity and improve weldability.

Description

[Technical Field]

[0001] The present invention relates to an electrode current collector and a lithium secondary battery containing the same, and more particularly to an electrode current collector and a lithium secondary battery containing the same that can simultaneously ensure stability and improve battery performance. [Background technology]

[0002] As technological development and demand for electric vehicles and energy storage systems (ESS) increase, the demand for batteries as an energy source is rapidly growing, and consequently, research is being conducted on batteries that can meet a variety of needs.

[0003] In particular, to enable longer usage times on a single charge, the battery capacity needs to be increased, and this requires the technology to increase the electrode area. However, during the process of increasing the electrode area, there is a possibility that the performance of the electrodes will decrease, and in the event of a fire, there is a risk of thermal runaway and thermal propagation to other electrodes.

[0004] In lithium-ion batteries, a rapid increase in electrode temperature can occur due to thermal and physical factors. Thermal factors include overcharging and overloading due to misuse or malfunction of chargers, while physical factors include damage to the separator due to external impact, causing an internal short circuit when the negative and positive electrode materials come into contact, resulting in a rapid increase in electrode temperature. When the electrode temperature rises rapidly in this way, the electrolyte and lithium react, or hydrogen and oxygen are generated inside the battery, making the battery extremely unstable. This can lead to the decomposition of the electrolyte solvent, generating gases, which can ignite and potentially cause the battery to explode.

[0005] Conventional lithium secondary batteries included only a single metal layer as the electrode current collector. Specifically, an aluminum single metal layer was used as the positive electrode current collector, and a copper single metal layer was used as the negative electrode current collector. However, such a single metal layer has very high electrical conductivity and thermal conductivity, and the time to reach a very high temperature instantaneously from abnormal battery behavior is very short. Therefore, there is a risk of thermal propagation due to thermal runaway.

[0006] Therefore, conventionally, instead of the electrode current collector, by using an electrode current collector (metallized film) including a resin layer interposed between two metal layers, it is possible to reduce the weight compared to an electrode current collector made of metal, significantly improve the energy density per unit weight, and cause a short circuit between the electrodes during a fire to improve safety.

[0007] However, in the case of the electrode current collector which is the metallized film, conventionally, compared with a pure metal electrode current collector, since it has a structure with a resin layer interposed therebetween, there is a problem that the electrical resistivity may be large, and research on a method capable of minimizing the damage of the electrical resistivity is required.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention is for solving the above problems. By including particles having both conductor and insulator characteristics in the resin layer of the metallized film current collector, it functions as a conductor during charging and discharging of the battery to improve electrical conductivity and improve the output characteristics of the battery. When a heat problem occurs, it maintains the insulation of the resin layer, is excellent in stability from fire and the effect of preventing thermal runaway, can be lightweight, and can realize an improvement in energy density. An electrode current collector and a lithium secondary battery including the same are provided.

Means for Solving the Problems

[0009] [1] An electrode current collector according to one embodiment of the present invention includes a resin layer, a first metal layer disposed on one surface of the resin layer, and a second metal layer disposed on the other surface of the resin layer, wherein the first metal layer and the second metal layer each independently have a thickness of 3.0 μm or less, the resin layer contains a metal oxide, and the thickness of the first metal layer or the second metal layer (T M ) relative to the thickness of the resin layer (T R ) ratio (T R / T M ) is 1 to 24, and the resin layer contains a metal oxide represented by the following chemical formula 1. [Chemical formula 1] M1 x M2 y O z In the above chemical formula 1, M1 is one or more transition metals selected from the group consisting of Al, Ga, In, Sn, Pb, and Bi, M2 is one or more transition metals selected from the group consisting of Ti, Zr, Nb, Ru, Hf, Cr, Mo, Ni, Co, V, Y, and Zn, where 0 ≤ x ≤ 4, 0 ≤ y ≤ 4, and 1 ≤ z ≤ 8, where x and y are not simultaneously 0, and x, y, and z are defined considering the oxidation states of M1 and M2 and the oxidation state of oxygen.

[0010] [2] In [1] above, the metal oxide may include one or more selected from the group consisting of lead oxide (PbO), ruthenium dioxide (RuO2), alumina (Al2O3), zirconia (ZrO2), bismuth ruthenate (Bi2Ru2O7), and bismuth iridate (Bi2Ir2O7).

[0011] [3] In [1] and / or [2] above, the metal oxide may be 10% to 60% by weight of the total weight of the resin layer.

[0012] [4] In any one or more of the above [1] to [3], the metal oxide may have an average particle size of 0.5 μm to 2.0 μm.

[0013] [5] In any one or more of the above [1] to [4], the resin layer may further include one or more selected from the group consisting of polyester resins, epoxy resins, phenolic resins, melamine resins, urethane resins, silicone resins, vinyl acetate resins, rubber resins, acrylic resins, and polyether urethane resins.

[0014] [6] In any one or more of the above [1] to [5], the first metal layer and the second metal layer may each independently include one or more selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, and aluminum-cadmium alloys.

[0015] [7] In any one or more of the above [1] to [6], the resin layer may have a thickness of 2 μm to 12 μm.

[0016] [8] In any one or more of the above [1] to [7], the first metal layer and the second metal layer may have a thickness of 0.2 μm to 2.5 μm, respectively.

[0017] [9] In any one or more of the above [1] to [8], the resin layer may have a thickness deviation of 10% or less.

[0018]

[10] In any one or more of the above [1] to [9], the first metal layer and the second metal layer may each independently have a thickness deviation of 5% or less.

[0019]

[11] Another embodiment of the present invention provides a lithium secondary battery comprising an electrode assembly having a structure in which a plurality of electrodes and a plurality of separators are alternately stacked, wherein the electrodes comprise an electrode current collector and an electrode active material layer disposed on the electrode current collector, and at least one of the plurality of electrode current collectors is the electrode current collector described above.

[0020]

[12] A battery module according to yet another embodiment of the present invention includes a plurality of the above-described lithium secondary batteries. [Effects of the Invention]

[0021] The electrode current collector according to the present invention includes a resin layer between two metal layers, and the resin layer contains a metal oxide that can have both conductive and insulator properties depending on the surrounding environment. This has the advantage of improving the flow of current even within the resin layer when the battery is running, and reducing the electrical resistivity of the metallized film, as well as ensuring safety in the event of thermal problems arising from the insulating properties of the resin layer of the metallized film.

[0022] Furthermore, the electrode current collector also has the advantage that the problem of poor weldability due to the resin layer interposed between the electrode tab and the electrode tab can be improved by the metal components contained in the metal oxide.

[0023] Furthermore, in the lithium secondary battery according to the present invention, the metal oxide contained in the resin layer of the electrode current collector functions as an insulator when a problem occurs, maintaining the insulation of the resin layer. This improves safety not only against foreign objects such as nail penetration, but also by delaying thermal propagation in the event of an actual fire.

[0024] Furthermore, since the electrode current collector has a structure that includes a resin layer which is relatively lighter than an electrode current collector made of metal alone, and a metal layer which is arranged as a thin film on the resin layer, it is possible to reduce the weight of the battery and improve the energy density per unit weight. [Brief explanation of the drawing]

[0025] [Figure 1] This is an example of a cross-sectional view of an electrode current collector according to one embodiment of the present invention. [Figure 2]This is another example of a cross-sectional view of an electrode current collector according to one embodiment of the present invention. [Modes for carrying out the invention]

[0026] The advantages and features of the present invention, as well as methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be realized in a variety of different forms, provided that these embodiments are provided to complete the disclosure of the present invention and to fully inform a person ordinary skill in the art to which the invention pertains, and the present invention is defined by the claims. Throughout the specification, the same reference numerals refer to the same components.

[0027] Unless otherwise defined, all terms used herein (including technical and scientific terms) should be used in a way that can be commonly understood by a person of ordinary skill in the art to which this invention pertains. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless explicitly defined otherwise.

[0028] The terms used herein are for illustrative purposes only and do not limit the invention. In this specification, singular nouns include plural nouns unless otherwise specified. The terms “comprises” and / or “comprising” as used in this specification do not preclude the presence or addition of one or more other components in addition to those mentioned.

[0029] In this specification, when a part is said to include a component, this means that, unless otherwise specified, it may include other components rather than excluding them.

[0030] In this specification, "A and / or B" means A, or B, or A and B.

[0031] In this specification, unless otherwise explicitly indicated, "%" means weight %.

[0032] In this specification, "average particle size" means the particle size corresponding to the average value of the weight percentage in the particle size distribution curve, and unless otherwise explicitly indicated, it means weight %. The average particle size can be measured with an electron microscope or an optical microscope after cutting a sample of the pouch-type battery case.

[0033] In this specification, each of the electrode current collector, the lithium secondary battery, and the battery module includes one or more of the technical features and / or technical configurations described below, and these technical features and / or technical configurations can be combined in various ways.

[0034] Electrode current collector The electrode current collector according to one embodiment of the present invention includes a resin layer, a first metal layer disposed on one surface of the resin layer, and a second metal layer disposed on the other surface of the resin layer.

[0035] Further, each of the first metal layer and the second metal layer independently has a thickness of 3.0 μm or less, the resin layer contains a metal oxide represented by the following Chemical Formula 1, and the ratio (T M ) of the thickness (T R ) of the resin layer to the thickness (T R / T M ) of the first metal layer or the second metal layer is 1 to 24. [Chemical Formula 1] M1 x M2<好的,我将为你翻译这段文本。请提供需要翻译的文本。O z In the above chemical formula 1, M1 is one or more transition metals selected from the group consisting of Al, Ga, In, Sn, Pb, and Bi, M2 is one or more transition metals selected from the group consisting of Ti, Zr, Nb, Ru, Hf, Cr, Mo, Ni, Co, V, Y, and Zn, where 0 ≤ x ≤ 4, 0 ≤ y ≤ 4, and 1 ≤ z ≤ 8, where x and y are not simultaneously 0, and x, y, and z are defined considering the oxidation states of M1 and M2 and the oxidation state of oxygen.

[0036] The electrode current collector according to the present invention will be described below with reference to Figures 1 and 2.

[0037] Figures 1 and 2 are illustrative cross-sectional views of an electrode current collector according to one embodiment of the present invention.

[0038] Referring to Figure 1, an electrode current collector according to one embodiment of the present invention includes a resin layer 11, a first metal layer 12 disposed on one surface of the resin layer, and a second metal layer 13 disposed on the other surface of the resin layer, wherein the resin layer contains a metal oxide 14.

[0039] Alternatively, as in Figure 2, there may be a structure with a total of three resin layers between the first metal layer 12 and the second metal layer 13, where the second resin layer 11b is positioned in contact with the first metal layer 12, and the third resin layer 11c is positioned in contact with the second metal layer 13, and the metal oxide 14 may have a structure that is contained in the innermost first resin layer 11a.

[0040] Conventional lithium-ion batteries contain only a single metal layer as the electrode current collector; specifically, a single aluminum metal layer is used as the positive electrode current collector, and a single copper metal layer is used as the negative electrode current collector. However, such single metal layers have very high electrical and thermal conductivity, and the time it takes for the battery to reach high temperatures instantaneously due to abnormal battery behavior is very short, posing a risk of thermal runaway and thermal propagation. Furthermore, there is a high risk of explosion when damaged by penetration by a needle-shaped object.

[0041] Therefore, by using an electrode current collector that includes a resin layer interposed between two metal layers instead of the conventional electrode current collector, it is possible to reduce the weight compared to an electrode current collector made of metal, dramatically improve the energy density per unit weight, delay heat propagation due to the insulating properties of the resin layer between the metal layers in the event of a fire, and reduce the risk of explosion even in the event of damage due to penetration.

[0042] However, because the electrode current collector has a structure in which a resin layer is interposed between metal layers, the current flow path is reduced compared to conventional current collectors, which inevitably leads to an increase in electrical resistivity and causes many problems when welding with the electrode tab.

[0043] To solve these problems, one might consider inserting metal powder into the resin layer to improve electrical conductivity and weldability. However, if only a small amount or very small particles are added, no improvement is observed. Furthermore, if the amount of metal powder is sufficient to improve both electrical conductivity and weldability, the properties of the current collector, which is a metallized film designed to delay heat propagation, cannot be utilized, resulting in poor stability against through-damage.

[0044] Furthermore, when carbon materials such as carbon black, graphene, and graphite are added as conductive materials in electrodes to improve electrical conductivity, it is difficult to expect safety, similar to adding metal powder, and there is a problem that weldability does not improve at all.

[0045] Therefore, the inventors have devised an electrode current collector that improves and increases the current flow path by inserting a metal oxide into the resin layer of the electrode current collector, which is a metallized film, thereby solving the problem of electrical resistivity and improving weldability, and ultimately ensuring the heat propagation delay and safety against through-damage that the metallized film aims to achieve.

[0046] metal oxides According to one embodiment of the present invention, the electrode current collector is characterized in that the resin layer contains a metal oxide. The resin layer placed in the middle of the electrode current collector is electrically non-conductive and has high electrical resistivity, which can be a source of interference when the electrode current collector performs its intended function. However, by including a metal oxide in the resin layer, the dielectric properties of the metal oxide can be utilized to function as a conductor when current is flowing, thereby reducing the high electrical resistivity of the resin layer.

[0047] Furthermore, if the battery is damaged by external impact, especially if it is pierced by a needle-like object, the metal oxide, being an insulator itself, can be useful in preventing electrical short circuits between electrodes and delaying heat propagation.

[0048] The aforementioned metal oxide can be represented, for example, by the following chemical formula 1. [Chemical formula 1] M1 x M2 y O z In the above chemical formula 1, M1 is a post-transition metal, M2 is a transition metal, and 0 ≤ x ≤ 4, 0 ≤ y ≤ 4, and 1 ≤ z ≤ 8, where x and y are not simultaneously 0, and x, y, and z can be defined considering the oxidation states of M1 and M2 and the oxidation state of oxygen. Specifically, M1 can be Al, Ga, In, Sn, Pb, or Bi, and M2 can be Ti, Zr, Nb, Ru, Hf, Cr, Mo, Ni, Co, V, Y, or Zn.

[0049] Preferably, the composite metal oxide may include one or more selected from the group consisting of lead oxide (PbO), ruthenium dioxide (RuO2), alumina (Al2O3), zirconia (ZrO2), bismuth ruthenate (Bi2Ru2O7), and bismuth iridate (Bi2Ir2O7).

[0050] On the other hand, as mentioned above, if metal or carbon materials are used instead of the metal oxide, it may be difficult to achieve the same effects as when a metallized film is used instead of a single metal film. In other words, if the resin layer, which is the intermediate layer of the metallized film, contains a carbon material or a material with relatively high conductivity, such as a metal, instead of a metal oxide, when the current collector is damaged, it increases the possibility of a short circuit, causing problems such as explosions during penetration or accelerated heat propagation, and although it is a low probability, it can cause problems such as dendrite growth where lithium is deposited due to the generation of leakage current. Therefore, the material included as a filler in the resin layer must be a metal oxide.

[0051] The metal oxide can be present in an amount of 10% to 60% by weight relative to the total weight of the resin layer, preferably 15% or more by weight, 20% or more by weight, or 25% or more by weight, and preferably 55% or less by weight, or 50% or less by weight. When the metal oxide is included in the above range, the effect of improving the current flow path is maximized, and it is possible to prevent problems such as electrical short circuits caused by external impact or penetration by needle-like objects, similar to conventional electrode current collectors, from being included in excessive amounts and negatively affecting the improvement of weight reduction. Furthermore, it is preferable that it be included in an amount of at least 10% by weight to show the effect of improving the current flow path.

[0052] Furthermore, the metal oxide can have an average particle size of 0.5 μm to 2.0 μm, preferably 0.7 μm or more, 1.0 μm or more, or 1.2 μm or more, and preferably 2.0 μm or less, 1.8 μm or less, or 1.5 μm or less. Such an average particle size can be appropriately selected considering the thickness of the resin layer, and can also be selected considering the type and density of the metal oxide material to be applied.

[0053] Thickness and thickness ratio of the metal layer According to one embodiment of the present invention, the thickness of the first metal layer and the second metal layer of the electrode current collector is independently 3.0 μm or less, and the thickness of the first metal layer or the second metal layer (T M) relative to the thickness of the resin layer (T R ) ratio (T R / T M The range is 1 to 24.

[0054] When the aforementioned metal oxide is included in the resin layer, in order to obtain effects such as weight reduction, improved safety, and reduced electrical resistivity of the battery, both the thickness of the metal layer and the ratio of the thicknesses of the resin layer to the metal layer must be considered. Even if a metal oxide is included, if the thickness of the metal layer and the ratio of the thicknesses of these layers are not properly controlled, the intended effects of adding the metal oxide will not be properly achieved.

[0055] As a result, the electrode current collector according to one embodiment of the present invention is characterized in that the thickness of each metal layer located on both sides of the resin layer is 3.0 μm or less. The metallized film, that is, the electrode current collector of the present invention, does not affect the original function of the current collector and can also be expected to improve energy density due to weight reduction. If the thickness of each metal layer exceeds 3.0 μm, it is difficult to expect such effects, and the likelihood of heat propagation due to thermal runaway increases as the thickness of the metal layer increases. Therefore, in order to ensure improved safety, it is preferable that the thickness of the metal layer does not exceed 3.0 μm.

[0056] The thickness of each of the aforementioned metal layers can preferably be 0.2 μm or more, 0.5 μm or more, 0.7 μm or more, more preferably 1.0 μm or more, 2.5 μm or less, 2.3 μm or less, or 2.0 μm or less. In this case, the effects described above can be achieved more easily.

[0057] Furthermore, the metal oxide can be incorporated into the resin layer to improve the current flow path, and in order to obtain this effect, the ratio of the thickness of the metal layer to the resin layer must be between 1 and 24. If the thickness ratio is less than 1, the resin layer becomes too thin, making it difficult to ensure safety when a short circuit occurs due to external impact or penetration by a needle-like object. If the thickness ratio exceeds 24, the resin layer becomes too thick, which may reduce the energy density, and even with the addition of the metal oxide, the current flow path will not be improved, and the effect of reducing electrical resistivity cannot be obtained.

[0058] The ratio of the thickness of the resin layer to the metal layer has a lower limit of 1 or more, preferably 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more, and an upper limit of 24 or less, preferably 23 or less, 22 or less, 21 or less, or 20 or less.

[0059] resin layer According to one embodiment of the present invention, the resin layer 11, as a matrix resin, can prevent abnormal heat transfer between the electrode current collector and the electrode active material layer, and can also lighten the electrode current collector and mitigate external shocks.

[0060] As described above, the resin layer 11 contains a metal oxide, and the explanation regarding the metal oxide is as stated above, so it will be omitted here.

[0061] The resin layer 11 may include, for example, one or more resins selected from the group consisting of polyester resins, epoxy resins, phenolic resins, melamine resins, urethane resins, silicone resins, vinyl acetate resins, rubber resins, acrylic resins, and polyether urethane resins.

[0062] Specifically, the resin layer 11 may include one or more selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyacrylonitrile (PAN), polyethylene (PE), polyamide (PA), and polypropylene (PP). Furthermore, the resin layer 11 may be a thermosetting resin or a photocurable resin, and preferably a UV-curable resin.

[0063] If necessary, the resin layer 11 may contain photoinitiators such as benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, or peroxide compounds, or photoinitiators such as amines or quinones, and may further contain curing accelerators such as amine-based, imidazole-based, phosphorus-based, boron-based, or phosphorus-boron-based accelerators. It may also contain thermal initiators such as azobisnitrile, benzoyl peroxide, or acetone peroxide.

[0064] According to one embodiment of the present invention, the resin layer 11 may have a thickness of 2 μm to 12 μm, with a lower limit preferably being 3 μm or more, 4 μm or more, 5 μm or more, or 6 μm or more, and an upper limit preferably being 11 μm or less, 10 μm or less, 9 μm or less, or 8 μm or less. When the thickness of the resin layer 11 is applied within this range, effects such as preventing abnormal heat transfer, reducing the weight of the electrode current collector, mitigating external shocks, and preventing an increase in the overall thickness of the battery can be expected.

[0065] Furthermore, the thickness deviation of the resin layer 11 can be 10% or less. It is preferable to control the thickness deviation of the resin layer to 10% or less. In this case, the joint surface between the resin layer and the metal layer can be densely bonded without any gaps, which prevents problems such as damage due to external impacts or fires caused by short circuits between the metal layers due to penetration by needle-like objects.

[0066] metal layer According to one embodiment of the present invention, the first metal layer 12 and / or the second metal layer 13 may include one or more selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, and aluminum-cadmium alloy. Although not particularly limited, it is preferable to include aluminum when forming a positive electrode current collector, and it is preferable to include copper when forming a negative electrode current collector.

[0067] Since the thickness of each of the aforementioned metal layers is as described above, its description is omitted.

[0068] Furthermore, the first metal layer 12 and / or the second metal layer 13 can also form fine irregularities on their surfaces to strengthen the bonding force with the electrode bonding layer, and can be used in various forms such as films, sheets, foils, meshes, porous materials, foams, and nonwoven fabrics.

[0069] However, even when forming fine irregularities on the surface, it is preferable that the thickness deviation of the metal layer be 5% or less. While forming irregularities on the surface can improve adhesion with the electrode bonding layer, if the deviation between the thickness at the highest and lowest points of the irregularities exceeds 5%, it can cause problems such as damage due to external impact or fire due to short circuits between metal layers caused by penetration by needle-like objects.

[0070] An electrode current collector 10 according to one embodiment of the present invention includes a resin layer 11 and a first metal layer 12 and a second metal layer 13 on both sides thereof, respectively, and the resin layer 11 contains a metal oxide 14. The metal oxide can be inserted into the resin layer by methods such as extruding together with a polymer that will become the material of the resin layer, which is in a molten state, and the metal layers can be formed on the resin layer by, for example, a method of physical vapor deposition. There are no particular limitations as long as a method can be used to manufacture the electrode current collector of the present invention that satisfies the above conditions, but in order to form the metal layers as thin as possible, it is preferable to form them by a method of physical vapor deposition.

[0071] Lithium-ion rechargeable battery The lithium secondary battery according to the present invention includes the electrode current collector of the present invention described above.

[0072] Specifically, the lithium secondary battery includes an electrode assembly having a structure in which a plurality of electrodes and a plurality of separators are alternately stacked, the electrode includes an electrode current collector and an electrode active material layer disposed on the electrode current collector, and at least one of the plurality of electrode current collectors is the electrode current collector of the present invention described above.

[0073] More specifically, the lithium secondary battery according to the present invention includes an electrode assembly in which a positive electrode, a separator, and a negative electrode are stacked in order, the separator being positioned between the positive electrode and the negative electrode, the positive electrode including a positive electrode current collector and a positive electrode active material layer stacked on the positive electrode current collector, the negative electrode including a negative electrode current collector and a negative electrode active material layer stacked on the negative electrode current collector, and at least one of the positive electrode current collector and the negative electrode current collector is the electrode current collector of the present invention as described above.

[0074] positive electrode According to one embodiment of the present invention, the positive electrode can be provided with a metallized film as described above as a positive electrode current collector, and may include a positive electrode current collector and a positive electrode active material layer disposed thereon.

[0075] The positive electrode active material layer may, as necessary, selectively include a conductive material and a binder along with the positive electrode active material.

[0076] The positive electrode active material is a substance capable of undergoing an electrochemical reaction, and as a lithium transition metal oxide, it contains two or more transition metals, for example, layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) substituted with one or more transition metals; lithium manganese oxide substituted with one or more transition metals; chemical formula LiNi 1-y M y Lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn, or Ga, containing one or more of the above elements, and 0.01 ≤ y ≤ 0.7); Li 1+z Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li 1+z Ni 0.4 Mn 0.4 Co 0.2 Li 1+z Ni b Mn c Co 1-(b+c+d) M d O (2-e) A e Lithium nickel cobalt manganese composite oxide represented by (where -0.5 ≤ z ≤ 0.5, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.2, 0 ≤ e ≤ 0.2, b + c + d < 1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl); chemical formula Li 1+x M 1-y M' y PO 4-z X zExamples include, but are not limited to, olivine-based lithium metal phosphate (where M = transition metal, preferably Fe, Mn, Co, or Ni; M' = Al, Mg, or Ti; X = F, S, or N; -0.5 ≤ x ≤ +0.5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.1). The positive electrode active material can be present in an amount of 80% to 99% by weight, preferably 90% to 98% by weight, relative to the total weight of the positive electrode active material layer.

[0077] The conductive material is used to impart conductivity to the electrodes and can be used without particular limitations in a battery that does not cause chemical changes and has electronic conductivity. 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, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. Of these, one or more can be used. The conductive material may be included in an amount of 0.01% to 10% by weight, preferably 0.1% to 9% by weight, and more preferably 0.1% to 5% by weight, relative to the total weight of the positive electrode active material layer.

[0078] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which the hydrogen atoms of these materials are substituted with Li, Na, or Ca, or various copolymers thereof. One of these materials alone or a mixture of two or more materials can be used. The binder may be present in an amount of 1% to 30% by weight, preferably 1% to 20% by weight, and more preferably 1% to 10% by weight, relative to the total weight of the positive electrode active material layer.

[0079] The positive electrode can be manufactured by a conventional method for manufacturing a positive electrode, except that the positive electrode active material is used. Specifically, it can be manufactured by coating a positive electrode slurry composition, prepared by dissolving or dispersing the positive electrode active material and, if necessary, a binder, a conductive material, and a dispersant selectively in a solvent, onto a positive electrode current collector, followed by drying and rolling.

[0080] The solvent can be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and one or more of these can be used individually or in mixtures of two or more. The amount of solvent used should be sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, taking into consideration the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that allows for excellent thickness uniformity when applied for the manufacture of the positive electrode.

[0081] Alternatively, the positive electrode can also be manufactured by casting the positive electrode slurry composition onto another support, peeling it off the support, and then laminating the resulting film onto the positive electrode current collector.

[0082] Separator The separator separates the negative and positive electrodes and provides a passage for lithium ions to move. It can be used without particular limitations as long as it is a separator typically used in lithium secondary batteries. Particularly preferred is one that exhibits low resistance to ion movement in the electrolyte and has excellent electrolyte moisture absorption capacity. Specifically, porous polymer films, such as polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof, can be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. Furthermore, coated separators containing ceramic components or polymeric substances can be used to ensure heat resistance or mechanical strength, and can be selectively used in single-layer or multi-layer structures.

[0083] electrolyte Furthermore, the electrolytes used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0084] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0085] The aforementioned organic solvent can be used without particular limitations, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the aforementioned organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and can include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0086] The lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions for use in lithium secondary batteries. Specifically, the anion of the lithium salt is F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - The lithium salt can be one or more selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably used within the range of 0.1M to 4.0M, preferably 0.5M to 3.0M, and more preferably 1.0M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte can exhibit excellent electrolyte performance due to having appropriate conductivity and viscosity, and lithium ions can move effectively.

[0087] In addition to the components of the electrolyte, the electrolyte may also contain one or more additives for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphite, triethyl alcoholamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethyl alcohol, or aluminum trichloride. Here, the additive may be present in an amount of 0.1% to 10.0% by weight relative to the total weight of the electrolyte.

[0088] negative electrode The negative electrode includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0089] According to one embodiment of the present invention, the negative electrode can be provided with a metallized film as described above as a negative electrode current collector, and may include a negative electrode current collector and a negative electrode active material layer disposed thereon.

[0090] The negative electrode active material layer may selectively include a binder and a conductive material together with the negative electrode active material.

[0091] As the negative electrode active material, compounds capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. a(0 < a < 2), metal oxides such as SnO2, vanadium oxides, and lithium vanadium oxides that can be doped and undoped with lithium; or composites containing the metal compound and a carbonaceous material such as Si-C composites or Sn-C composites, etc. Any one or a mixture of two or more of these can be used. Further, as the negative electrode active material, a thin film of metallic lithium can also be used. Also, any of low-crystalline carbon and high-crystalline carbon, etc. can be used as the carbon material. Representative examples of low-crystalline carbon are soft carbon and hard carbon, and representative examples of high-crystalline carbon are amorphous, plate-like, scaly, spherical or fibrous natural graphite or artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature heat-treated carbons such as petroleum or coal tar pitch derived cokes.

[0092] The negative electrode active material can be contained in an amount of 80 wt% to 99 wt%, 82 wt% to 99 wt%, or 84 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0093] The binder is a component that helps in the adhesion between the conductive material, the active material, and the current collector, and is usually added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluorine rubber, and various copolymers thereof.

[0094] The conductive material is a component for further improving the conductivity of the negative electrode active material and can be included in an amount of 1% to 30% by weight, 1% to 20% by weight, or 1% to 10% by weight relative to the total weight of the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and examples of such materials that can be used include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0095] The negative electrode active material layer can be manufactured by coating a negative electrode slurry composition, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and then drying it, or by casting the negative electrode slurry composition onto another support, peeling it off this support, and then laminating the resulting film onto the negative electrode current collector.

[0096] Furthermore, the lithium secondary battery may selectively further include a battery container for housing the electrode assembly comprising the positive electrode, separator, and negative electrode, and a sealing member for sealing the battery container.

[0097] Furthermore, the lithium secondary battery according to the present invention exhibits excellent discharge capacity, output characteristics, and capacity retention rate stably, making it useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0098] In particular, to enable longer battery life on a single charge, the battery capacity needs to be increased, and this requires large-area electrode technology. However, increasing the electrode area can reduce electrode performance, and in the event of a fire, there is a risk of thermal runaway and thermal propagation to other electrodes.

[0099] Therefore, according to another embodiment of the present invention, a battery module including a plurality of the lithium secondary batteries and a battery pack including a plurality of the battery modules are provided.

[0100] The battery module refers to a battery assembly in which a predetermined number of lithium secondary batteries are placed together in a frame to protect them from external shocks, heat, vibrations, etc. The battery pack refers to the final form of a battery system installed in an electric vehicle or the like.

[0101] The aforementioned battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0102] When the battery module and battery pack according to the present invention include multiple electrode current collectors, they can actually maximize safety through thermal propagation in the event of a fire, and enable higher battery capacity and larger battery area.

[0103] Hereinafter, embodiments of the present invention will be described in detail so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.

[0104] Examples and Comparative Examples Example 1 An electrode current collector was manufactured by physically vapor-depositing (PVD) aluminum metal to a thickness of 1 μm on both sides of polyethylene terephthalate (PET), which contains 30% by weight of lead oxide (PbO) with an average particle size of 0.5 μm and has a thickness of 6 μm, to form a first metal layer and a second metal layer.

[0105] Example 2 An electrode current collector was manufactured by physically vapor-depositing (PVD) aluminum metal to a thickness of 1 μm on both sides of polyethylene terephthalate (PET), which contains 50% by weight of bismuth ruthenate (Bi2Ru2O7) with an average particle size of 0.5 μm, and has a thickness of 10 μm, to form a first metal layer and a second metal layer.

[0106] Example 3 An electrode current collector was manufactured in the same manner as in Example 1, except that 30% by weight of ruthenium dioxide (RuO2), with an average particle size of 1.0 μm, was used instead of lead oxide (PbO), with an average particle size of 0.5 μm.

[0107] Comparative Example 1 Aluminum metal with a thickness of 12 μm was used as the electrode current collector.

[0108] Comparative Example 2 An electrode current collector was manufactured by physically vapor-depositing (PVD) aluminum metal to a thickness of 1 μm on both sides of polyethylene terephthalate (PET) that does not contain metal oxides and has a thickness of 6 μm, thereby forming a first metal layer and a second metal layer.

[0109] Comparative Example 3 The electrode current collector was manufactured in the same manner as in Example 1, except that polyethylene terephthalate (PET) with a thickness of 2 μm and aluminum metal with a thickness of 3 μm were used.

[0110] Comparative Example 4 The electrode current collector was manufactured in the same manner as in Example 1, except that polyethylene terephthalate (PET) with a thickness of 40 μm and aluminum metal with a thickness of 1.5 μm were used.

[0111] Comparative Example 5 The electrode current collector was manufactured in the same manner as in Example 1, except that polyethylene terephthalate (PET) with a thickness of 8 μm and aluminum metal with a thickness of 5 μm were used.

[0112] Comparative Example 6 An electrode current collector was manufactured in the same manner as in Example 1, except that 30% by weight of carbon black with an average particle size of 1.0 μm was used instead of lead oxide (PbO) with an average particle size of 0.5 μm.

[0113] Comparative Example 7 An electrode current collector was manufactured in the same manner as in Example 1, except that it contained 30% by weight of aluminum metal powder with an average particle size of 1.0 μm, instead of lead oxide (PbO) with an average particle size of 0.5 μm.

[0114] Experimental Example 1 Using the electrode current collectors manufactured in Examples 1-3 and Comparative Examples 1-7, lithium secondary batteries were manufactured as described below. Their resistance characteristics and safety were evaluated by 1) electrical resistivity, 2) heat propagation delay test, 3) nail penetration test, and 4) weldability test, and the results are shown in Table 1 below. In Table 1, "◎" indicates very good, "○" indicates good, "△" indicates average, and "×" indicates poor.

[0115] Manufacturing of lithium-ion batteries A cathode slurry was prepared by mixing a cathode active material (NCM65 1520), a conductive material (Li-435), and a PVDF binder (KF9700, AD-c01) in N-methylpyrrolidone in a weight ratio of 96.5:1.5:2.0.

[0116] After applying the positive electrode slurry to one surface of the electrode current collectors manufactured in Examples 1-3 and Comparative Examples 1-7, the electrodes were dried at 140°C and then rolled to produce positive electrodes.

[0117] Graphite was used as the negative electrode active material. Along with this, a negative electrode slurry containing a binder and conductive material was applied to copper foil, dried, and the negative electrode was manufactured.

[0118] After manufacturing an electrode assembly by interposing a separator between the positive and negative electrodes produced by the method described above, the assembly was placed inside a battery case, and then an electrolyte was injected into the case to produce a battery cell. The electrolyte was prepared by dissolving 0.7 M LiPF6 in a mixed organic solvent consisting of ethylene carbonate (EC):propylene carbonate (PC):ethyl methyl carbonate (EMC) in a volume ratio of 2:1:7.

[0119] Specifically, the experimental methods for 1) electrical resistivity, 2) time delay effect on thermal propagation, 3) safety from nail penetration, and 4) weldability are as follows.

[0120] 1) Electrical resistivity: The surface resistance of the electrode current collectors manufactured in the above examples and comparative examples was measured using a 4-point probe device and evaluated in four steps.

[0121] 2) Heat propagation delay testFive of the manufactured battery cells were used as one module, and heat was applied to one battery cell at a rate of 0.5°C / sec using a heating pad. The heat transferred to adjacent cells was measured using thermocouples, and the degree of time delay in heat propagation was confirmed and evaluated in four steps.

[0122] 3) Nail piercing test The manufactured battery cells were subjected to a nail-piercing experiment using a sharp nail type at a speed of 0.1 mm / s. If ignition occurred, it was evaluated as ×; otherwise, it was evaluated as ○.

[0123] 4) Weldability test After stacking 10 electrode current collectors manufactured in the above examples and comparative examples, welding is performed. If any one of the welded electrode current collectors separates or a pinhole with a diameter of approximately 3 mm or more occurs, it is evaluated as ×. If separation does not occur but a crack or a pinhole with a diameter of less than approximately 3 mm occurs, it is evaluated as △. If no cracks, pinholes, or separation occur, it is evaluated as ○ or ◎, with ○ and ◎ being evaluated differently depending on the degree of strength.

[0124] [Table 1]

[0125] Referring to Table 1, it can be confirmed that in Examples 1 to 3, the electrical resistivity is improved compared to Comparative Example 2, which uses a current collector in which a resin layer is arranged between metal layers as a metallized film, and that excellent results are shown in the heat propagation delay test and nail penetration test, as well as excellent weldability. On the other hand, in Comparative Examples 1 to 7, it can be confirmed that when the electrical properties and / or weldability are excellent, the evaluation results for safety are considerably inferior, and when safety is guaranteed to a certain extent, the electrical properties and weldability are evaluated as inferior.

[0126] Specifically, referring to conventional aluminum foils like Comparative Example 1, Comparative Example 3 where the thickness ratio is less than 1 and the metal layer is thicker than the resin layer, Comparative Example 5 where the resin layer is thicker than the metal layer and the metal layer exceeds 3 μm even when the thickness ratio exceeds 1, and Comparative Example 7 in which metal powder is added to the resin layer, it can be confirmed that there is no improvement in terms of safety, as with conventional aluminum current collectors. Furthermore, in the cases of Comparative Examples 2 and 4, where the resin layer is too thick or does not contain metal oxides, the electrical resistivity characteristics do not improve, and although safety can be ensured, it can be confirmed that there is a problem of a significant decrease in output performance. [Explanation of Symbols]

[0127] 11 Resin layer 11a 1st resin layer 11b 2nd resin layer 11c 3rd resin layer 12 1st metal layer 13 Second metal layer 14 Metal Oxides

Claims

1. It includes a resin layer, a first metal layer disposed on one surface of the resin layer, and a second metal layer disposed on the other surface of the resin layer. The first metal layer and the second metal layer each independently have a thickness of 3.0 μm or less. The thickness (T) of the first or second metal layer Ｍ ) The thickness of the resin layer (T Ｒ ) ratio (T Ｒ / T Ｍ ) is 1 to 24, The aforementioned resin layer is an electrode current collector containing a metal oxide represented by the following chemical formula 1. [Chemical formula 1] M1 ｘ M2 ｙ O ｚ In the above chemical formula 1, M1 is one or more transition metals selected from the group consisting of Al, Ga, In, Sn, Pb, and Bi, and M2 is one or more transition metals selected from the group consisting of Ti, Zr, Nb, Ru, Hf, Cr, Mo, Ni, Co, V, Y, and Zn, where 0 ≤ x ≤ 4, 0 ≤ y ≤ 4, and 1 ≤ z ≤ 8, where x and y are not simultaneously 0, and x, y, and z are defined considering the oxidation states of M1 and M2 and the oxidation state of oxygen.

2. The metal oxide is lead oxide (PbO), ruthenium dioxide (RuO ２ ), alumina (Al ２ O ３ ), zirconia (ZrO ２ ), bismuth ruthenate (Bi ２ Ru ２ O ７ ), and bismuth iridate (Bi ２ Ir ２ O ７ ), and the electrode current collector according to claim 1, comprising one or more selected from the group consisting of

3. The electrode current collector according to claim 1, wherein the metal oxide is present in an amount of 10% to 60% by weight relative to the total weight of the resin layer.

4. The electrode current collector according to claim 1, wherein the metal oxide has an average particle size of 0.5 μm to 2.0 μm.

5. The electrode current collector according to claim 1, wherein the resin layer further comprises one or more selected from the group consisting of polyester resin, epoxy resin, phenolic resin, melamine resin, urethane resin, silicone resin, vinyl acetate resin, rubber resin, acrylic resin, and polyether urethane resin.

6. The electrode current collector according to claim 1, wherein the first metal layer and the second metal layer each independently contain one or more selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, and aluminum-cadmium alloy.

7. The electrode current collector according to claim 1, wherein the resin layer has a thickness of 2 μm to 12 μm.

8. The electrode current collector according to claim 1, wherein the first metal layer and the second metal layer each independently have a thickness of 0.2 μm to 2.5 μm.

9. The electrode current collector according to claim 1, wherein the resin layer has a thickness deviation of 10% or less.

10. The electrode current collector according to claim 1, wherein the first metal layer and the second metal layer each independently have a thickness deviation of 5% or less.

11. The electrode assembly includes a structure in which multiple electrodes and multiple separators are stacked alternately, The electrode includes an electrode current collector and an electrode active material layer disposed on the electrode current collector. A lithium secondary battery wherein at least one of the plurality of electrode current collectors is the electrode current collector described in claim 1.

12. A battery module comprising a plurality of lithium secondary batteries as described in claim 11.

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