Electrode assembly, secondary battery, battery pack, and automobile

Abstract

One embodiment of the present invention provides an electrode assembly having a structure in which a positive electrode, a separator, and a negative electrode are stacked and wound, the negative electrode including an in-tab provided at an end located at a mandrel part among both ends in a direction perpendicular to a winding axis of the electrode assembly, the in-tab being provided to surround 50% or more of a surface of the negative electrode facing the mandrel part, and a secondary battery, a battery pack, and a vehicle including the electrode assembly.

Description

[Technical field]

[0001] The present invention relates to an electrode assembly, a secondary battery, a battery pack, and an automobile.

[0002] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0133219, filed with the Korean Intellectual Property Office on October 17, 2022, the entire contents of which are incorporated herein by reference.

[0003] This application claims the benefit of the filing date of Korean Patent Application No. 10-2023-0137388, filed with the Korean Intellectual Property Office on October 16, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0004] Secondary batteries, which have high applicability across product groups and electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are powered by electrical sources.

[0005] Such secondary batteries have the primary advantage of dramatically reducing the use of fossil fuels, as well as the advantage of not producing any by-products from the use of energy, and are therefore attracting attention as a new energy source that is environmentally friendly and can improve energy efficiency.

[0006] Currently, the types of secondary batteries that are widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydrogen batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack may be configured by connecting a plurality of battery cells in series. Also, a battery pack may be configured by connecting a plurality of secondary batteries in parallel according to the charge / discharge capacity required for the battery pack. Therefore, the number and electrical connection form of the secondary batteries included in the battery pack may be variously set according to the required output voltage and / or charge / discharge capacity. Meanwhile, cylindrical, square, and pouch-type secondary batteries are known as types of secondary batteries, and the secondary battery may be a cylindrical battery. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENTS The present invention provides an electrode assembly and a secondary battery that prevent deformation of a mandrel portion of a negative electrode of the electrode assembly and prevent short circuits caused by damage to a separator.

[0008] Another object of the present invention is to provide a battery pack including a secondary battery having the above-mentioned improved structure, and a vehicle including the same.

[0009] However, the technical problems that the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0010] One embodiment of the present invention provides an electrode assembly having a structure in which a positive electrode, a separator, and a negative electrode are stacked and wound, the negative electrode including an in-tab provided at one end located at a mandrel part among both ends in a direction perpendicular to a winding axis of the electrode assembly, the in-tab being provided to surround 50% or more of a surface of the negative electrode facing the mandrel part.

[0011] Another embodiment of the present invention provides a secondary battery including an electrode assembly according to an embodiment of the present invention.

[0012] Another embodiment of the present invention provides a battery pack including the secondary battery according to the above embodiment.

[0013] Another embodiment of the present invention provides a vehicle including a battery pack according to the above embodiment. Effect of the Invention

[0014] In a secondary battery, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the electrode assembly is wound up to form a jelly roll-shaped electrode assembly, which is then inserted into a battery can together with an electrolyte to form a battery. When the jelly roll-shaped electrode assembly is wound around a mandrel, the negative electrode expands and contracts during charging and discharging, generating stress within the electrode assembly.

[0015] The mandrel portion of the electrode assembly is an empty space, and the stress generated during charging and discharging is suppressed by the battery can, which causes the mandrel portion to deform. If the deformation of the mandrel portion becomes severe, stress may be generated, such as the occurrence of broken portions of the electrodes, which may cause a short circuit due to damage to the separator inside the electrode assembly.

[0016] According to an embodiment of the present invention, an in-tab provided at an end portion located on the mandrel portion of the negative electrode of the electrode assembly is provided to surround 50% or more of a surface of the negative electrode facing the mandrel portion, thereby preventing expansion stress inside the electrode assembly from acting on the mandrel portion, thereby preventing deformation of the mandrel portion of the electrode assembly and occurrence of short circuits due to damage to the separator, which is advantageous in ensuring battery stability.

[0017] However, the advantageous effects obtained through the present invention are not limited to the effects described above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Brief description of the drawings]

[0018] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical spirit of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters depicted in such drawings.

[0019] [Figure 1] 1A is a schematic diagram of a conventional intubation device according to a comparative example of the present invention, and FIG. 1B is a schematic diagram of an intubation device according to an embodiment of the present invention. [Diagram 2] 1A is a schematic cross-sectional view perpendicular to the winding shaft of an electrode assembly according to a comparative example of the present invention, and FIG. 1B is a schematic cross-sectional view perpendicular to the winding shaft of an electrode assembly according to an embodiment of the present invention. [Diagram 3] 11 is a diagram showing a process in which stress occurs within an electrode assembly due to charging and discharging in a secondary battery including an electrode assembly according to a comparative example of the present invention, and deformation occurs in a mandrel portion while the force of outward expansion is suppressed by the battery can. [Figure 4] 1 is a view showing an electrode of an electrode assembly according to an embodiment of the present invention before being wound; [Diagram 5] 1 is a diagram showing an electrode assembly according to an embodiment of the present invention. [Figure 6] 1 is a schematic diagram illustrating a negative electrode and a positive electrode of an electrode assembly according to an embodiment of the present invention. [Figure 7] 1 is a diagram showing a schematic configuration of a battery pack including a secondary battery according to an embodiment of the present invention. [Figure 8] 1 is a diagram showing a schematic configuration of a vehicle including a battery pack according to an embodiment of the present invention. [Figure 9] 13 is a diagram showing a problem that occurs when an in-tab is provided to surround less than 50% of the surface facing the mandrel portion. [Figure 10] 13 is a diagram showing a problem that occurs when an in-tab is provided to surround less than 50% of the surface facing the mandrel portion. [Explanation of symbols]

[0020] 1...electrode assembly 1' Conventional electrode assembly 2...Secondary battery 3. Battery pack 4-Pack Housing 5. Automotive 10...Positive electrode 11 Positive middle tab 11' Conventional positive middle tab 12: End portion located on the positive electrode mandrel portion 12': End portion located at the conventional positive electrode mandrel portion 13: End portion located on the outer periphery of the positive electrode 13': Conventional end located on the outer periphery of the positive electrode 14...Cathode active material layer 15 Positive electrode uncoated area 30...Negative electrode 31 Negative electrode insert 31' Conventional negative electrode intubation 32 Negative electrode outer tab 32' Conventional negative electrode outer tab 33 Negative electrode tab 34 End portion located at the negative electrode mandrel portion 34'....End portion located in conventional negative electrode mandrel portion 35 End portion located on the outer periphery of the negative electrode 35': Conventional end located on the outer periphery of the negative electrode 36...Negative electrode active material layer 37 Negative electrode uncoated area 38: Both ends of the electrode assembly in the vertical direction of the winding shaft 40: Surface facing the mandrel 41R: Surrounding area of ​​mandrel 51R: Surrounding portion of electrode assembly 31W ···Intubation width 31T ···Intubation thickness 311...Protrusion 312 ...recess I...Core O: Outermost part C: Electrode assembly winding shaft P: Perpendicular to the winding axis of the electrode assembly DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The terms and words used in this specification and claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that corresponds to the technical idea of ​​the present invention, based on the principle that an inventor can appropriately define the concept of a term in order to explain his / her invention in the best possible manner.

[0022] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless otherwise clearly indicated in the context.

[0023] In this specification, terms such as "including," "comprising," or "having" are intended to describe the presence of certain components, and do not preclude the presence or possible addition of other components.

[0024] Furthermore, the terms "unit" and "apparatus" used in this specification refer to a unit that processes at least one function or operation.

[0025] In this specification, the expression "on" a particular component is intended to express that the component is on one side of the particular component, and is not intended to limit the hierarchical relationship. It is also not limited to being in physical contact with the component, and means that there may be other components between the component and the component.

[0026] In this specification, the term "mandrel portion" refers to an empty space provided at the innermost part of the electrode assembly, which is provided when the jelly-roll-shaped electrode assembly is wound around a mandrel.

[0027] In this specification, the term "in-tab" refers to a tab provided at one end of an electrode assembly that is located at a mandrel portion, among both ends in a direction perpendicular to the winding axis.

[0028] The embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not fully represent the technical ideas of the present invention, so it should be understood that there may be various equivalents and modifications that can replace them at the time of this application.

[0029] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals are used to refer to the same components in different embodiments.

[0030] An embodiment of the present invention will now be described with reference to the drawings.

[0031] One embodiment of the present invention provides an electrode assembly having a structure in which a positive electrode, a separator, and a negative electrode are stacked and wound, the negative electrode including an in-tab provided at one end located at a mandrel part among both ends in a direction perpendicular to a winding axis of the electrode assembly, the in-tab being provided to surround 50% or more of a surface of the negative electrode facing the mandrel part.

[0032] The mandrel portion is provided at the innermost part of the electrode assembly and refers to an empty space provided when the electrode assembly in a jelly roll shape is wound around the mandrel. The empty space may be formed in a cylindrical shape.

[0033] The surface facing the mandrel portion means a surface that directly contacts the mandrel portion.

[0034] FIG. 4 is a view showing an electrode of an electrode assembly according to an embodiment of the present invention before being wound, and FIG. 5 is a view showing an electrode assembly according to an embodiment of the present invention.

[0035] 4 and 5, the in-tab 31 may be a tab provided at one of both ends of the electrode assembly 1 in a direction perpendicular to the winding axis, the end being located at a mandrel portion.

[0036] According to one embodiment, the in-tab 31 may be provided as a single continuous tab surrounding 50% or more of the surface 40 of the negative electrode facing the mandrel portion.

[0037] The surface 40 of the negative electrode facing the mandrel portion refers to the shaded portion in FIG. 4, for example, the surface facing the mandrel portion so as to surround a peripheral portion 41R of the mandrel portion of the electrode assembly 1.

[0038] The surface 40 of the negative electrode facing the mandrel portion may be provided in a non-coated portion 37 of the negative electrode where no electrode active material layer is provided.

[0039] 100% of the surface 40 of the negative electrode facing the mandrel portion may surround the peripheral portion 41R of the mandrel portion of the electrode assembly 1 by 100%.

[0040] Of both ends of the electrode assembly in a direction perpendicular to the winding axis, an end located at a mandrel portion may be provided at an innermost mandrel portion of the electrode assembly.

[0041] Since the inner tab 31 is provided to surround 50% or more of the surface 40 of the negative electrode 30 facing the mandrel portion, the internal rigidity of the mandrel portion is increased, and thus, it is possible to prevent the expansion stress inside the electrode assembly 1 from acting on the mandrel portion. This is advantageous in ensuring battery stability by preventing deformation of the mandrel portion of the electrode assembly 1 and preventing the occurrence of short circuits due to damage to the separator.

[0042] FIG. 1(a) is a schematic diagram of a conventional in-tube 31' according to a comparative example of the present invention, and FIG. 1(b) is a schematic diagram of a negative electrode in-tube 31 according to an embodiment of the present invention.

[0043] 1(a) and (b), the conventional in-tub 31' according to the comparative example of the present invention is relatively narrower in width than the in-tub 31 according to the embodiment of the present invention, and the tab cannot be provided to surround more than 50% of the surface facing the mandrel portion of the negative electrode, so that it is not possible to prevent the expansion stress inside the electrode assembly from acting on the mandrel portion.

[0044] The conventional in-tub 31' has a relatively narrow width compared to the in-tub 31 according to the embodiment of the present invention, and cannot be provided to surround more than 50% of the surface facing the mandrel part of the negative electrode not only when it is provided in the winding axis direction C of the electrode assembly, but also when it is provided obliquely and wound into a spiral shape, and a discontinuous section is generated in the spiral shape, which reduces the internal rigidity compared to the continuous in-tub 31 according to the present invention, and it is not possible to prevent the expansion stress inside the electrode assembly from acting on the mandrel part. In addition, burrs may be present in the discontinuous section of the tab due to the spiral shape, which may damage the separator, thereby weakening safety.

[0045] That is, when the electrode assembly has a structure in which it is wound around a mandrel part, stress is generated inside the electrode assembly as the negative electrode expands and contracts during charging and discharging. The stress generated during charging and discharging is suppressed by the battery can, and the mandrel part, which is an empty space, is deformed by this force. If the deformation of the mandrel part becomes severe, stress may be generated such that the electrode may break, which may cause a short circuit inside the electrode assembly due to damage to the separator.

[0046] 9 and 10 are diagrams showing problems when the in-tube 31 is provided to surround less than 50% of the surface facing the mandrel part. Specifically, FIG. 9 is a diagram showing a mandrel part deformed after activation and life evaluation, where (a) is a state where deformation begins after activation, and (b) is a state where deformation deepens after life evaluation. In addition, in the case of a cylindrical battery in which the in-tube 31 is provided to surround less than 50% of the surface facing the mandrel part, a heat release problem occurs along with the deformation of the mandrel part. Specifically, referring to FIG. 10, it can be seen that the temperature of the mandrel part (b) increases by about 2 to 3°C compared to the outer surface part (a) after the battery is discharged. That is, it was confirmed that when the in-tube 31 surrounds less than 50% of the surface facing the mandrel part, the mandrel part cannot release heat and the temperature increases.

[0047] Meanwhile, the in-tube 31 according to an embodiment of the present invention may be provided so as to surround 50% or more of the surface of the negative electrode facing the mandrel portion, for example, it may be provided continuously so as to surround the periphery of the mandrel portion of the electrode assembly.

[0048] Since the in-tube 31 is provided to surround more than 50% of the surface facing the mandrel portion, the rigidity of the mandrel portion is improved and deformation of the mandrel portion can be minimized, and the heat trapped in the mandrel portion is transferred through the in-tube 31, which is a metal body, to reduce the temperature of the mandrel portion.

[0049] The periphery of the mandrel of the electrode assembly refers to the periphery of the mandrel, which is an empty space around which the jelly-roll-shaped electrode assembly is wound.

[0050] Since the in-tube 31 is provided to surround 50% or more of the surface of the negative electrode facing the mandrel portion, it is possible to prevent expansion stress inside the electrode assembly from acting on the mandrel portion, thereby preventing deformation of the mandrel portion of the electrode assembly and occurrence of short circuits due to damage to the separator, which is advantageous in ensuring battery stability.

[0051] The fact that the in-tab 31 is provided to surround 50% or more of the surface facing the mandrel portion of the negative electrode means that the in-tab 31 is provided continuously to surround the periphery of the mandrel portion of the electrode assembly, meaning that, for example, one tab can be provided in a continuous shape to surround 50% or more of the surface facing the mandrel portion.

[0052] In the case where the in-tube is not provided continuously to surround the periphery of the mandrel part of the electrode assembly, for example, the conventional in-tube may be provided at an angle and then provided around the periphery of the mandrel part while being wound. When the conventional in-tube 31' is provided around the periphery of the mandrel part while being wound, the rigidity may be reduced compared to the in-tube 31 of the present invention, and when it is wound in a spiral shape, burrs at the corners of the tab may be positioned on the outer periphery of the mandrel part, which may result in damage to the separator and other safety issues.

[0053] FIG. 3 is a diagram showing a process in which stress occurs inside an electrode assembly due to charging and discharging in a secondary battery including an electrode assembly according to a comparative example of the present invention, and deformation occurs in a mandrel portion while the force of outward expansion is suppressed by the battery can.

[0054] In a secondary battery, a separator, which is an insulator, is interposed between a positive electrode and a negative electrode, and the electrode assembly is wound up to form a jelly-roll-shaped electrode assembly. The electrode assembly is then inserted into a battery can together with an electrolyte to form a battery.

[0055] The secondary battery may be a cylindrical secondary battery.

[0056] When a jelly roll-shaped electrode assembly has a structure in which it is wound around a mandrel part, stress is generated within the electrode assembly as the negative electrode expands and contracts during charging and discharging of a secondary battery including the electrode assembly. The mandrel part of the electrode assembly is an empty space, and the stress generated during charging and discharging is suppressed by the battery can from expanding outward, and the stress is applied within the electrode assembly, causing deformation of the mandrel part. If the deformation of the mandrel part becomes severe, stress may be generated, such as the occurrence of broken parts in the electrodes, which may cause a short circuit within the electrode assembly due to damage to the separator.

[0057] In one embodiment of the present invention, the negative electrode includes a current collector and an electrode active material layer provided on the current collector, the current collector including an uncoated portion where the electrode active material layer is not provided, the negative electrode including the uncoated portion at at least one end portion in a direction perpendicular to a winding axis of the electrode assembly, and the in-tab is provided in the uncoated portion provided at an end portion of the uncoated portion that is located on a mandrel portion.

[0058] Referring to FIG. 4, the negative electrode 30 has the in-tab 31 in the uncoated portion 37 provided at the end located on the mandrel portion, which has high conductivity and is favorable for electrical connection, and the resistance of the electrode assembly is reduced, which is favorable for energy density.

[0059] According to one embodiment of the present invention, a negative electrode tab 33 may be provided at either or both ends of the electrode assembly in a direction perpendicular to the winding axis.

[0060] FIG. 6 is a schematic diagram showing a negative electrode and a positive electrode of an electrode assembly according to an embodiment of the present invention.

[0061] 4 and 6, the negative electrode 30 according to an embodiment of the present invention may further include an outer tab 32 provided at an end located at the outer edge of both ends in a direction perpendicular to the winding axis of the electrode assembly. By including one more outer tab 32 in the negative electrode 30, an effect can be obtained in that the resistance of the electrode assembly decreases as the number of tabs increases.

[0062] As a result, the positive electrode 10 described below may have a free edge shape and a middle tab 11 structure in which the end of the positive electrode current collector and the end of the positive electrode active material layer 14 coincide with each other at the end perpendicular to the winding axis of the electrode assembly.

[0063] In the positive electrode free edge structure, when the electrode assembly is charged and discharged, the negative electrode 30 expands and contracts, which may increase stress at the portion where the free edge of the positive electrode 10 abuts. However, the internal rigidity of the mandrel portion is increased by the in-tube 31 of the negative electrode 30, which prevents deformation of the mandrel portion of the electrode assembly 1 and prevents the occurrence of a short circuit due to damage to the separator.

[0064] In addition, by further including the outer tab 32, the resistance of the electrode assembly 1 can be reduced, and the energy density can be increased.

[0065] As an example different from an embodiment of the present invention, a positive electrode tab may be located in the mandrel portion. An electrode assembly according to this structure generally has one positive electrode in-tab and one negative electrode outer tab, but has a problem in that the number of tabs is reduced compared to the electrode assembly structure according to the present invention, resulting in an increased resistance of the electrode assembly.

[0066] 2(a) is a schematic cross-sectional view perpendicular to the winding shaft of a conventional electrode assembly 1' according to a comparative example of the present invention, and (b) is a schematic cross-sectional view perpendicular to the winding shaft of an electrode assembly 1 according to an embodiment of the present invention. In this case, since the positive electrode has a free edge structure, the negative electrode may expand and contract during charging and discharging of the electrode assembly, which may increase stress at the portion where the positive electrode free edge abuts.

[0067] Referring to FIG. 2(a), the conventional in-tub 31' according to the comparative example of the present invention is relatively thin in width compared to the in-tub 31 according to the embodiment of the present invention, and the tab cannot be provided to surround more than 50% of the surface facing the mandrel portion of the negative electrode, so it is not possible to prevent the expansion stress inside the electrode assembly from acting on the mandrel portion.

[0068] The conventional in-tub 31' is relatively thin in width compared to the in-tub 31 according to the embodiment of the present invention, and when it is provided in the winding axis direction of the electrode assembly or obliquely and wound into a spiral shape, a discontinuous section is generated, and the internal rigidity is reduced compared to the continuous in-tub 31 according to the present invention, and it is not possible to prevent the expansion stress inside the conventional electrode assembly 1' from acting on the mandrel part. In addition, burrs may be present in the discontinuous section of the tab due to the spiral shape, which may damage the separator and is therefore vulnerable to safety.

[0069] Meanwhile, referring to Fig. 2(b), the in-tab 31 according to one embodiment of the present invention is a continuous tab that is provided to surround more than 50% of the surface of the negative electrode facing the mandrel portion, and can prevent the expansion stress inside the electrode assembly 1 from acting on the mandrel portion due to an increase in the internal rigidity of the mandrel portion. This prevents deformation of the mandrel portion of the electrode assembly 1 and the occurrence of short circuits due to damage to the separator, which is advantageous in ensuring battery stability. In addition, compared to a spiral-shaped tab, the in-tab 31 is provided continuously and does not have burrs, so there is no risk of the separator being damaged.

[0070] One embodiment of the present invention provides an electrode assembly 1, wherein the in-tube 31 is provided to surround 70% or more of the surface 40 facing the mandrel portion. Specifically, the in-tube 31 may be provided to surround 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more of the surface 40 facing the mandrel portion. The in-tube 31 may be provided to surround less than 100% or 100% of the surface 40 facing the mandrel portion.

[0071] Within this range, the inner tube 31 can maintain its rigidity and prevent the expansion stress inside the electrode assembly 1 from acting on the mandrel portion, thereby preventing deformation of the mandrel portion of the electrode assembly 1 and preventing the occurrence of short circuits due to damage to the separator, thereby ensuring battery stability.

[0072] In one embodiment of the present invention, the width of the in-tab is 80% or more and 100% or less of the length of the peripheral portion of the mandrel portion.

[0073] 4 and 5, the width 31W of the in-tab means the length of the in-tab in a direction perpendicular to the winding axis of the electrode assembly.

[0074] The peripheral portion 41R of the mandrel portion refers to the periphery of the mandrel portion, which is an empty space around which the jelly-roll-shaped electrode assembly is wound.

[0075] The width 31W of the in-tab may be 85% or more, 90% or more, or 95% or more of the length of the surrounding portion 41R of the mandrel portion. The width of the in-tab may be less than or equal to 100% of the length of the surrounding portion of the mandrel portion.

[0076] When the width 31W of the in-tube satisfies the above range, the in-tube 31 is provided to surround the peripheral portion 41R of the mandrel portion of the negative electrode, and the internal rigidity of the mandrel portion can be increased, thereby preventing the expansion stress inside the electrode assembly from acting on the mandrel portion. This is advantageous in preventing deformation of the mandrel portion of the electrode assembly and preventing the occurrence of short circuits due to damage to the separator, thereby ensuring battery stability.

[0077] In one embodiment of the present invention, the width of the in-tab is 15% to 20% of the length of the peripheral portion of the electrode assembly.

[0078] The peripheral portion 51R of the electrode assembly means a peripheral portion of an end portion of the electrode assembly 1 in the winding axis direction.

[0079] The width 31W of the in-tab may be 15.5% or more, or 16% or more, of the length of the peripheral portion 51R of the electrode assembly. The width 31W of the in-tab may be 19.5% or less, 19% or less, 18.5% or less, or 18% or less, of the length of the peripheral portion 51R of the electrode assembly.

[0080] When this range is satisfied, the inner tube 31 is provided to surround the peripheral portion 41R of the mandrel portion of the negative electrode, and the internal rigidity of the mandrel portion can be increased, thereby preventing the expansion stress inside the electrode assembly 1 from acting on the mandrel portion.

[0081] In one embodiment of the present invention, the in-tub 31 has a length extending in a direction perpendicular to the winding axis of the electrode assembly of 10 mm to 12 mm.

[0082] The length of the in-tub extended in a direction perpendicular to the winding axis of the electrode assembly may be the width 31W of the in-tub.

[0083] The in-tab 31 may have a length extending in a direction perpendicular to the winding shaft of the electrode assembly of 10.3 mm or more, 10.6 mm or more, or 10.9 mm or more. The in-tab 31 may have a length extending in a direction perpendicular to the winding shaft of the electrode assembly of 11.7 mm or less, 11.4 mm or less, or 11.1 mm or less.

[0084] When this range is satisfied, the inner tube 31 is provided to surround the periphery 41R of the mandrel part of the negative electrode, and the internal rigidity of the mandrel part can be increased, thereby preventing the expansion stress inside the electrode assembly 1 from acting on the mandrel part. This is advantageous in ensuring battery stability by preventing deformation of the mandrel part of the electrode assembly 1 and preventing the occurrence of short circuits due to damage to the separator.

[0085] In one embodiment of the present invention, the thickness of the intubation is 100 μm or more.

[0086] 2, the thickness 31T of the in-tube may be 110 μm or more, 120 μm or more, 130 μm or more, or 140 μm or more. The thickness of the in-tube may be 200 μm or less, 190 μm or less, 180 μm or less, or 170 μm or less.

[0087] When the thickness range is satisfied, the in-tube 31 can increase the internal rigidity of the mandrel portion, thereby preventing the expansion stress inside the electrode assembly 1 from acting on the mandrel portion. This is advantageous in ensuring battery stability by preventing deformation of the mandrel portion of the electrode assembly 1 and preventing short circuits caused by damage to the separator. In addition, since the in-tube 31 has appropriate rigidity within the thickness range, it is easy to wind the electrode assembly in a winding process.

[0088] One embodiment of the present invention provides an electrode assembly, wherein the in-tube has a thermal conductivity of 90 W / (m·K) or more.

[0089] The thermal conductivity is the difference in the degree to which heat is transferred from one side to another, and refers to the inherent property of a material that exhibits heat transfer. The thermal conductivity (k) can be measured by the following formula (1) under the conditions of 1 atmosphere and 293K (=20°C).

[0090] P=k×A(△T / L)-Equation (1) P=heat flow (W) A = area of ​​sample (m 2 ) L = sample thickness (m) △T = temperature difference (K or °C)

[0091] The in-tube may have a thermal conductivity of 91 W / (m·K) or more, 100 W / (m·K) or more, 200 W / (m·K) or more, 300 W / (m·K) or more, or 400 W / (m·K) or more. The in-tube may have a thermal conductivity of 450 W / (m·K) or less, 430 W / (m·K) or less, 410 W / (m·K) or less, or 405 W / (m·K) or less.

[0092] The in-tube may include at least one of copper and nickel, as described below, and in this case, the thermal conductivity of the copper may be 401 W / (m·K) and the thermal conductivity of the Ni may be 91 W / (m·K).

[0093] The in-tab may be provided as a clad tab in which a copper layer containing the copper and a nickel layer containing the nickel are bonded together. In this case, heat generated in the electrode assembly can be transferred from the copper layer, which has good thermal conductivity, and has a thermal conductivity similar to that of copper, which is advantageous for heat conduction.

[0094] 1(a) and 1(b), the conventional in-tube 31' according to the comparative example of the present invention is relatively narrower in width than the in-tube 31 according to the embodiment of the present invention, and when it is provided not only in the winding axial direction of the electrode assembly 1 but also when it is provided obliquely and wound into a spiral shape, it may have lower thermal conductivity than the in-tube 31 according to the embodiment of the present invention. Specifically, the conventional in-tube 31' is relatively narrow in width or has discontinuous sections in the spiral shape, and heat is transferred only in the narrow or spiral direction compared to the continuous in-tube 31 according to the present invention, but the in-tube 31 according to the embodiment of the present invention is advantageous in thermal conduction as heat can be transferred in any 2D direction.

[0095] In one embodiment of the present invention, the intubation material comprises at least one of copper and nickel.

[0096] The in-tub may include copper. The in-tub may include copper in an amount of 50% to 100% based on the total amount of the in-tub.

[0097] The in-tube may contain nickel. The in-tube may contain nickel in an amount of 0% to 50% based on 100% of the total.

[0098] The in-tub may be provided as a clad tub to which a copper layer containing the copper and a nickel layer containing the nickel are bonded.

[0099] By including the compound in the intub, the heat conduction of the electrode assembly including the intub may be more favorable.

[0100] One embodiment of the present invention provides an electrode assembly, wherein the in-tab includes a protrusion on one surface of an end portion in a winding axis direction of the electrode assembly.

[0101] 4 and 5, the protrusion 311 is a necessary configuration for welding to a battery can of a secondary battery including the electrode assembly 1, and the protrusion 311 may be bent and positioned at the center of a mandrel part and welded to the center of an inner bottom surface of the battery can, thereby electrically connecting the inner tab 31 and the battery can.

[0102] The center of the mandrel part means the central region of a vertical cross section of the winding shaft of the electrode assembly 1 at the mandrel part, and the center of the inner bottom surface of the battery can means the central region of a vertical cross section of the winding shaft of the electrode assembly at the inner bottom surface of the battery can.

[0103] In one embodiment of the present invention, the in-tab includes a recess on the other surface opposite to the one surface of the end portion in the winding axis direction of the electrode assembly.

[0104] The recess 312 is a configuration for convenience in an assembly process, and typically, when attaching the tab 31 to the electrode assembly 1, a predetermined length of the tab 31 is cut off and attached from a wound tab roll. If the protrusion 311 is present according to one embodiment of the present invention, the recess 312 may be unavoidably generated when cutting off the tab of the predetermined length.

[0105] In one embodiment of the present invention, the positive electrode includes a current collector and an electrode active material layer provided on the current collector, and an end of the positive electrode current collector and an end of the positive electrode active material layer coincide with each other at at least one of both ends in a direction perpendicular to a winding axis of the electrode assembly.

[0106] Referring to FIG. 6, the fact that an end of the positive electrode current collector and an end of the positive electrode active material layer 14 coincide with each other at an end of the positive electrode 10 may mean that the positive electrode 10 has a free edge in the electrode assembly 1, and that no uncoated portion 15 is formed at both ends of the positive electrode 10 in a direction P perpendicular to the winding axis of the electrode assembly 1.

[0107] The fact that an end of the positive electrode current collector and an end of the positive electrode active material layer 14 coincide with each other at an end of the positive electrode 10 means that the lengths of the positive electrode current collector and the positive electrode active material layer 14 at the end of the positive electrode are the same, and in this case, the length of the positive electrode current collector and the length of the positive electrode active material layer 14 may be within a general error range in the industry. For example, the length of the positive electrode current collector compared to the length of the positive electrode active material layer 14 at the end of the positive electrode may be +0.5% or less.

[0108] According to one embodiment, the end of the positive electrode may be provided at a winding start of the wound electrode assembly.

[0109] In one embodiment of the present invention, the positive electrode further includes a tab provided at a portion other than both ends in a direction perpendicular to the winding axis of the electrode assembly.

[0110] As described above, the positive electrode has a free edge structure, and therefore, the uncoated portion 15 may not be formed at both ends of the positive electrode in the direction P perpendicular to the winding axis of the electrode assembly.

[0111] As a result, the positive electrode may have a middle tab 11 structure, and the middle tab structure means that the electrode assembly 1 further includes tabs 11 provided at portions other than both ends in a direction P perpendicular to the winding axis. Therefore, both ends of the electrode assembly 1 in a direction P perpendicular to the winding axis may have free edges where no uncoated portion 15 is formed. The middle tab 11 may be provided in the positive electrode uncoated portion 15.

[0112] Referring to FIG. 6, the positive electrode 10 may have a free edge shape and a middle tab 11 structure in which an end of the positive electrode current collector and an end of the positive electrode active material layer 14 coincide with each other at an end perpendicular to the winding axis of the electrode assembly 1.

[0113] In the positive electrode free edge structure, when the electrode assembly 1 is charged and discharged, the negative electrode expands and contracts, which may increase stress at the portion where the positive electrode free edge abuts, but the internal rigidity of the mandrel part is increased by the in-tab 31 of the negative electrode 30, which prevents deformation of the mandrel part of the electrode assembly 1 and prevents short circuits caused by damage to the separator. In addition, the negative electrode 30 further includes an outer tab 32, which reduces the resistance of the electrode assembly and increases the energy density compared to when the positive electrode 10 and the negative electrode 30 each have one tab.

[0114] One embodiment of the present invention provides a secondary battery including an electrode assembly according to the above-described embodiment.

[0115] In the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art without any limitations.

[0116] Non-limiting examples of the positive electrode active material include conventional positive electrode active materials that can be used for the positive electrode of conventional electrochemical devices. In particular, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a lithium composite oxide obtained by combining these may be used.

[0117] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one or more elements of Li, Na, and K; M includes at least one or more elements selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; x, y, z, and the stoichiometric coefficients of the components included in M ​​are selected such that the compound maintains electroneutrality).

[0118] In another example, the positive electrode active material is an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O 2 -(1-x)Li 2 M 2 O 3 (M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1).

[0119] In another embodiment, the positive electrode active material has the general chemical formula LiM 1 xFe 1 -xM 2 yP 1 -yM 3 zO 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains halogen elements optionally including F; <a≦2、0≦x≦1、0≦y<1、0≦z<1;a、x、y、z、M 1 , M 2 , and M. 3 The stoichiometric coefficients of the components included in are chosen so that the compound remains electroneutral), or Li 3 M 2 (PO 4 ) 3 [M includes at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0120] Preferably, the positive electrode active material may include primary particles and / or secondary particles formed by agglomeration of the primary particles.

[0121] Non-limiting examples of the negative electrode active material include conventional negative electrode active materials that can be used in the negative electrodes of conventional electrochemical devices, and in particular, lithium adsorbent materials such as lithium metal or lithium alloys, carbon, petroleum coke, activated carbon, graphite, or other carbons can be used.

[0122] In one example, the negative electrode active material may be a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, or the like. 2 , SnO 2 Metal oxides such as the above can also be used as the negative electrode active material. As the carbon material, low crystalline carbon, high crystalline carbon, etc. can both be used.

[0123] Non-limiting examples of positive electrode current collectors include foils made of aluminum, nickel, or a combination thereof, and non-limiting examples of negative electrode current collectors include foils made of copper, gold, nickel, or a copper alloy, or a combination thereof.

[0124] The separation membrane may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., or a laminate of these. As another example, the separation membrane may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of a high melting point glass fiber, a polyethylene terephthalate fiber, etc.

[0125] At least one surface of the separation membrane may include a coating layer of inorganic particles.

[0126] Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that there is an interstitial volume between adjacent particles.

[0127] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), PB(Mg 3 Nb 2 / 3 )O 3 -PbTiO 3 (PMN-PT), BaTiO 3 , hafnia (HfO 2 ), SrTiO 3 , TiO 2 , Al 2 O 3 , ZrO 2 , SnO 2 , CEO 2 , MgO, CaO, ZnO, and Y 2 O 3 The composition may include at least one material selected from the group consisting of:

[0128] The electrolyte is A + B - The salt may have the structure: + Li + , Na + , K + and combinations of these cations. - is F - , Cl - , Br - , I - , NO 3 - , N(CN) 2 - , B.F. 4 - , ClO 4- 、AlO 4 - 、AlCl 4 - 、PF 6 - 、SbF 6 - 、AsF 6 - 、BF 2 C 2 O 4 - 、BC 4 O 8 - 、(CF 3 ) 2 PF 4 - 、(CF 3 ) 3 PF 3 - 、(CF 3 ) 4 PF 2 - 、(CF 3 ) 5 PF - 、(CF 3 ) 6 P - 、CF 3 SO 3 - 、C 4 F 9 SO 3 - 、CF 3 CF 2 SO 3 - 、(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - 、CF 3 CF 2 (CF 3 ) 2 CO - 、(CF 3 SO 2 ) 2 CH - 、(SF 5 ) 3 C - 、(CF 3 SO2 ) 3 C - , C.F. 3 (CF 2 ) 7 SO 3 - , C.F. 3 CO 2 - , C.H. 3 CO 2 - , SCN - and (CF 3 CF 2 SO 2 ) 2 N - The anion includes one or more anions selected from the group consisting of:

[0129] The electrolyte may also be dissolved in an organic solvent, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0130] Another embodiment of the present invention provides a battery pack including at least one of the secondary batteries described above.

[0131] The cylindrical secondary battery according to the above-described embodiments may be used to manufacture a battery pack.

[0132] FIG. 7 is a diagram showing a schematic configuration of a battery pack 3 including a secondary battery 2 according to an embodiment of the present invention.

[0133] 7, a battery pack 3 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical secondary batteries, and a pack housing 4 that accommodates the assembly. The cylindrical secondary battery is the secondary battery 2 according to the embodiment described above. For ease of illustration, components such as bus bars for electrically connecting the cylindrical secondary batteries, a cooling unit, and external terminals are omitted in the drawings.

[0134] Another embodiment of the present invention provides a vehicle including at least one battery pack as described above.

[0135] The battery pack can be installed in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0136] FIG. 8 is a diagram for explaining an automobile 5 including the battery pack 3 of FIG.

[0137] 8, an automobile 5 according to an embodiment of the present invention includes a battery pack 3 according to an embodiment of the present invention. The automobile receives power from the battery pack 3 according to an embodiment of the present invention to operate.

[0138] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person having ordinary knowledge in the technical field to which the present invention pertains to make various modifications and variations within the technical spirit of the present invention and the equivalent scope of the claims described below.

Claims

1. An electrode assembly having a structure in which a positive electrode, a separator, and a negative electrode are stacked and wound, the negative electrode includes an in-tube provided at an end located at a mandrel portion among both ends of the electrode assembly in a direction perpendicular to the winding axis, The in-tube is provided to surround 50% or more of a surface of the negative electrode facing the mandrel portion.

2. the negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector, the negative electrode current collector includes a non-coated portion where the negative electrode active material layer is not provided, The electrode assembly of claim 1 , wherein the in-tab is provided in a non-coated portion provided at an end located at a mandrel portion among both ends of the negative electrode in a direction perpendicular to a winding axis of the electrode assembly.

3. The electrode assembly according to claim 1 , wherein the in-tab is provided so as to surround 70% or more of a surface facing the mandrel portion.

4. The electrode assembly according to claim 1 , wherein the width of the in-tub is 80% or more and 100% or less of the length of the periphery of the mandrel portion.

5. The electrode assembly of claim 1 , wherein the width of the in-tube is 15% to 20% of the length of the circumference of the electrode assembly.

6. The electrode assembly of claim 1, wherein the in-tab has a length extending in a direction perpendicular to a winding axis of the electrode assembly of 10 to 12 mm.

7. The electrode assembly of claim 1 , wherein the thickness of the intubation is 100 μm or more.

8. The electrode assembly according to claim 1 , wherein the in-tube has a thermal conductivity of 90 W / (m·K) or more.

9. The electrode assembly of claim 1 , wherein the intubation comprises at least one of copper and nickel.

10. The electrode assembly according to claim 1 , wherein the in-tab includes a protrusion on one surface of an end portion in a winding axis direction of the electrode assembly.

11. The electrode assembly according to claim 1 , wherein the in-tab includes a recess on another surface opposite to one surface of the end of the electrode assembly in the winding axis direction.

12. the positive electrode includes a positive electrode current collector and a positive electrode active material layer provided on the positive electrode current collector, The electrode assembly according to claim 1 , wherein an end of the positive electrode current collector and an end of the positive electrode active material layer coincide with each other at at least one of both ends in a direction perpendicular to a winding axis of the electrode assembly.

13. The electrode assembly according to claim 1 , wherein the positive electrode further includes a tab provided at a portion other than both ends in a direction perpendicular to the winding axis of the electrode assembly.

14. A secondary battery comprising the electrode assembly according to any one of claims 1 to 13.

15. A battery pack comprising the secondary battery according to claim 14.

16. A motor vehicle comprising at least one battery pack according to claim 15.

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