Electrode assembly with excellent electrolyte impregnation, and battery, battery pack, and automobile including the same

Abstract

According to an embodiment of the present invention, there is provided an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound around a winding shaft to define a core and an outer circumferential surface. The first electrode includes an active material portion coated with an active material layer along the winding direction, and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion is used as an electrode tab, and the first uncoated portion has a plurality of impregnation slits formed along a circumferential direction of the electrode assembly, and longitudinal extension lines of adjacent impregnation slits along the circumferential direction do not overlap each other.

Description

[Technical field]

[0001] The present invention relates to an electrode assembly having excellent electrolyte impregnation property, and a battery, a battery pack, and an automobile including the same.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0032990 filed on March 12, 2021, and Korean Patent Application No. 10-2021-0081138 filed on June 22, 2021, and the contents disclosed in the specification and drawings of said applications are incorporated herein in their entirety. [Background technology]

[0003] Secondary batteries, which are easily applicable to various products and have 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 driven by electrical sources. These secondary batteries are attracting attention as a new energy source because they are environmentally friendly and improve energy efficiency by not producing any by-products associated with energy use, in addition to their primary advantage of dramatically reducing the use of fossil fuels.

[0004] Currently, types of secondary batteries that are widely used include lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a battery pack is constructed by connecting a plurality of battery cells in series. Also, a battery pack may be constructed by connecting a plurality of battery cells in parallel according to a charge / discharge capacity required for the battery pack. Therefore, the number of battery cells included in the battery pack can be variously set according to a required output voltage or charge / discharge capacity.

[0005] Meanwhile, in a typical secondary battery, an electrode assembly is impregnated with an electrolyte solution, so that lithium ions can move smoothly to generate a current. In this regard, the electrolyte impregnation is a very important factor that affects the life and capacity of a battery, and a higher electrolyte impregnation rate is more advantageous.

[0006] Meanwhile, as the demand for secondary batteries for electric vehicles has increased recently, the development of medium- and large-sized batteries has become more important in order to improve the energy density. However, as the size of the battery increases, the impregnation characteristics of the electrolyte at the center of the electrode of the electrode assembly may decrease, which may result in poor battery performance. In other words, the existing electrode assembly structure has limitations in improving the electrolyte impregnation of medium- and large-sized batteries.

[0007] Therefore, a method for improving the electrolyte impregnation of the electrode assembly of a battery is required.

[0008] Meanwhile, as batteries are recently applied to electric vehicles, the form factor of the battery is increasing, that is, the diameter and height of the battery are increasing compared to batteries having conventional form factors such as 1865 and 2170. The increase in form factor brings about an increase in energy density, an increase in safety against thermal runaway, and an improvement in cooling efficiency.

[0009] The energy density of a battery can be further increased when the form factor is increased and the wasted space inside the battery housing is minimized, which necessitates designing the overall structure of the battery to increase the electrolyte impregnation of the electrode assembly while increasing the capacity of the battery. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above problems, and aims to improve the electrolyte impregnation of a battery by forming an impregnation slit, through which an electrolyte can pass, in an uncoated portion of the battery and uniformly impregnating the entire electrode assembly contained inside the battery with the electrolyte.

[0011] Another object of the present invention is to reduce the internal resistance of the battery by bending one side end of the uncoated portion to increase the contact area between the uncoated portion of the electrode assembly and the current collector.

[0012] Another object of the present invention is to improve the bonding strength between the electrode assembly and the current collector by ensuring a large contact area between the non-coated portion of the electrode assembly and the current collector.

[0013] However, the technical problems that the present invention aims to solve are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0014] According to one aspect of the invention for achieving the above object, there is provided an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound around a winding shaft to define a core and an outer circumferential surface, the first electrode including an active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion is used as an electrode tab, the first uncoated portion has a plurality of impregnation slits formed along a circumferential direction of the electrode assembly, and longitudinal extensions of adjacent impregnation slits along the circumferential direction do not overlap each other.

[0015] Desirably, the plurality of impregnation slits may have a shape extending in a direction parallel to the circumferential direction.

[0016] In particular, the length of the impregnation slit in the circumferential direction may be longer than the length of the impregnation slit in the winding axis direction.

[0017] In one aspect of the present invention, among the plurality of impregnation slits, adjacent ones of the plurality of impregnation slits in the circumferential direction may not be formed on the same line, but may be provided at different heights in the winding axis direction.

[0018] In another aspect of the present invention, among the plurality of impregnation slits, adjacent impregnation slits along the circumferential direction may be spaced apart at a predetermined interval in a direction parallel to a winding shaft of the electrode assembly.

[0019] In still another aspect of the present invention, the longitudinal extension lines of the impregnation slits located on the left and right sides of any one of the impregnation slits may overlap each other.

[0020] In yet another aspect of the present invention, the intervals between adjacent impregnation slits in the circumferential direction may be constant.

[0021] In still another aspect of the present invention, the interval between adjacent impregnation slits in the circumferential direction may gradually increase from a core side to an outer periphery side of the electrode assembly.

[0022] In yet another aspect of the present invention, the circumferential length of the impregnation slit may be constant.

[0023] Alternatively, the circumferential length of the impregnation slit may gradually increase from the core side to the outer periphery side of the electrode assembly.

[0024] In yet another aspect of the present invention, the plurality of impregnation slits may have a configuration inclined at a predetermined angle with respect to a line extending along the circumferential direction.

[0025] Here, the multiple impregnation slits may be parallel to each other.

[0026] In yet another aspect of the present invention, among the plurality of impregnation slits, adjacent impregnation slits along a radial direction of the electrode assembly may at least partially overlap each other to provide an impregnation path through which an electrolyte can pass along the radial direction.

[0027] Preferably, the impregnation path may be provided to a predetermined depth in the radial direction from the outer circumferential surface of the electrode assembly.

[0028] In yet another aspect of the present invention, at least one of the first uncoated portion and the second uncoated portion may include a plurality of segment pieces spaced apart from each other along a circumferential direction of the electrode assembly and separated by a plurality of cut lines formed from an end of the first uncoated portion to a predetermined depth.

[0029] Preferably, the plurality of segment pieces may be overlapped in multiple ways along a radial direction of the electrode assembly to form a bent surface.

[0030] Here, the bent surface may include a lamination number increasing section in which the number of overlaps of the segment pieces gradually increases from the outer periphery side of the electrode assembly toward the core side to a maximum value, and a lamination number uniform section from the radius point where the number of overlaps becomes maximum to the radius point where the innermost segment piece is present.

[0031] In one embodiment, the plurality of segment pieces may be folded in a radial direction of the electrode assembly to cover at least a portion of one surface of the electrode assembly perpendicular to the winding axis.

[0032] In another embodiment, the plurality of segment pieces may be bent in a radial direction of the electrode assembly to cover an entire surface of the electrode assembly perpendicular to the winding axis.

[0033] In yet another aspect of the present invention, among the plurality of impregnation slits, adjacent impregnation slits along a radial direction of the electrode assembly may at least partially overlap each other to provide an impregnation path through which an electrolyte can pass along the radial direction.

[0034] Preferably, the impregnation path may be provided to a predetermined depth along the radial direction from the outer circumferential surface of the electrode assembly.

[0035] More preferably, the depth of the impregnation path may be greater than or equal to the radial length of the area covered by the segment on one side of the electrode assembly perpendicular to the winding axis.

[0036] In yet another aspect of the present invention, the first uncoated portion may include a first line that is an imaginary straight line spaced a first distance from the active material portion and parallel to a boundary line between the active material portion and the first uncoated portion, and a second line that is an imaginary straight line spaced a second distance from an end of the cut line and parallel to the boundary line between the active material portion and the first uncoated portion.

[0037] Here, the impregnation slit may be provided on at least one of the first line and the second line.

[0038] Preferably, the impregnation slits may be provided on the first line and the second line in a circumferential direction of the electrode assembly.

[0039] In yet another aspect of the present invention, the impregnation slits located on different lines do not have to overlap each other in the winding axial direction.

[0040] In still another aspect of the present invention, the circumferential length of the impregnation slits located on the same line may gradually increase from a core side to an outer periphery side of the electrode assembly.

[0041] In still another aspect of the present invention, the intervals between the impregnation slits located on the same line may gradually increase from the core side to the outer periphery side of the electrode assembly.

[0042] In yet another aspect of the present invention, the first non-coated portion may further include at least one intermediate line which is an imaginary straight line located between the first line and the second line, parallel to the first line and the second line, and spaced a predetermined distance from the first line and the second line.

[0043] Here, the non-coated portion may further include an intermediate impregnation slit provided on the intermediate line.

[0044] Preferably, the number of intermediate lines is multiple, and the intermediate impregnation slits may be provided alternately along the circumferential direction on the multiple intermediate lines.

[0045] In still another aspect of the present invention, the number of the impregnation slits provided on the first line, the second line and the at least one intermediate line may be the same.

[0046] In yet another aspect of the present invention, the incision line and the impregnation slit may be spaced apart from each other by a predetermined distance.

[0047] Preferably, the distance between the incision line and the impregnation slit may be 1 mm to 5 mm.

[0048] In one aspect of the present invention, the first uncoated portion may be located on an upper portion of the electrode assembly.

[0049] Preferably, the first electrode is a negative electrode.

[0050] In another aspect of the present invention, the second electrode includes an active material portion coated with an active material layer along the winding direction, and a second uncoated portion not coated with an active material layer, and at least a portion of the second uncoated portion can be used as an electrode tab.

[0051] Here, the second non-coated portion may have a plurality of impregnation slits formed along a circumferential direction of the electrode assembly, and longitudinal extension lines of adjacent impregnation slits along the circumferential direction may not overlap each other.

[0052] A battery according to an embodiment of the present invention includes the electrode assembly according to the above-described embodiment.

[0053] Meanwhile, a battery pack according to an embodiment of the present invention includes at least one battery according to an embodiment of the present invention.

[0054] Moreover, the automobile according to the embodiment of the present invention includes a battery pack according to the embodiment of the present invention. Effect of the Invention

[0055] According to the present invention, it is possible to improve the electrolyte impregnation property of the electrode assembly.

[0056] In particular, according to the present invention, a path through which the electrolyte can pass is formed in the non-coated portion of the battery, and the electrolyte is uniformly impregnated into the entire electrode assembly contained inside the battery, thereby improving the electrolyte impregnation of the battery.

[0057] In addition, according to the present invention, the contact area between the non-coated portion of the electrode assembly and the current collector is increased, thereby reducing the internal resistance of the battery.

[0058] Furthermore, according to the present invention, the contact area between the non-coated portion of the electrode assembly and the current collector can be made large, thereby improving the bonding strength between the electrode assembly and the current collector.

[0059] In addition, the present invention can provide various other effects, which will be described in each embodiment, or the description of effects that can be easily inferred by a person skilled in the art will be omitted.

[0060] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0061] [Figure 1] 1 is a view illustrating an electrode assembly according to an embodiment of the present invention; [Figure 2a] 2 is a view for explaining a state in which a first electrode applied to the electrode assembly of FIG. 1 is spread out. FIG. [Figure 2b] FIG. 2 is a diagram illustrating a first line and a second line provided in a non-coating portion. [Figure 2c] FIG. 2 is a diagram illustrating a first line, a second line, and a third line provided in a non-coating portion. [Figure 2d] 2b is a diagram for explaining a first electrode having a different form from the first electrode shown in FIG. 2a. FIG. [Figure 2e] FIG. 2b is a diagram illustrating a first electrode having a further different form from the first electrode shown in FIG. 2a. [Diagram 3] FIG. 2b is a diagram illustrating a first electrode having a further different form from the first electrode shown in FIG. 2a. [Figure 4] FIG. 2 is a plan view of the electrode assembly of FIG. [Figure 5a] FIG. 2 is a front cross-sectional view of the electrode assembly of FIG. [Figure 5b] FIG. 5b is an enlarged view of a segment portion in FIG. 5a. [Figure 6] 5 is a plan view of an electrode assembly having a different configuration from the electrode assembly shown in FIG. 4. [Figure 7] FIG. 7 is a front cross-sectional view of the electrode assembly of FIG. 6. [Figure 8] 1 is a view illustrating a battery including an electrode assembly according to an embodiment of the present invention. [Figure 9] 1 is a diagram illustrating a battery pack including a battery according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram for explaining a vehicle including the battery pack of FIG. 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts according to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0063] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0064] In order to facilitate understanding of the present invention, the accompanying drawings may be drawn not to scale but with some components exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0065] The fact that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include a deviation that is considered to be a low level in the art, for example, a deviation within 5%. Furthermore, the uniformity of any parameter in a given region may mean that it is uniform on average.

[0066] Terms such as "first" and "second" are used to describe various components, but the components are not limited by these terms. These terms are used to distinguish only one component from another component, and unless otherwise specified, the first component may be the second component.

[0067] Throughout the specification, unless otherwise specified, each element may be singular or plural.

[0068] When a structure is disposed "on (or under)" a component or "above (or below)" a component, it may mean that the structure is disposed directly on the upper (or lower) surface of the component, but also that other structures may be interposed between the component and the structure disposed above (or below) the component.

[0069] Additionally, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that there may be other components "intervening" between each component, or each component may be "coupled," "coupled," or "connected" by other components.

[0070] Throughout the specification, unless otherwise specified, a reference to "A and / or B" means "A," "B," or "A and B," and a reference to "C through D" means at least C and at most D, unless otherwise specified.

[0071] For ease of explanation, in this specification, the direction along the longitudinal direction of the winding shaft of the electrode assembly wound in a wound form is referred to as the axial direction Y. The direction surrounding the winding shaft is referred to as the circumferential direction or circumferential direction X. The direction approaching or moving away from the winding shaft is referred to as the radial direction. Of these, the direction particularly approaching the winding shaft is referred to as the centripetal direction or core side direction, and the direction moving away from the winding shaft is referred to as the centrifugal direction or core side direction.

[0072] Fig. 1 is a view for explaining an electrode assembly according to an embodiment of the present invention, Fig. 2a is a view for explaining a state in which a first electrode applied to the electrode assembly of Fig. 1 is unfolded, and Figs. 2b to 3 are views for explaining a first electrode having a different form from the first electrode shown in Fig. 2a.

[0073] 1 and 2a, the electrode assembly is an electrode assembly having a shape in which a laminate including a first electrode, a second electrode, and a separator is wound up.

[0074] The first electrode includes a first non-coated portion having a first polarity, and the second electrode includes a second non-coated portion having a second polarity. For example, the first electrode may be a positive electrode or a negative electrode, and the second electrode may be an electrode having an opposite polarity to the first electrode. A separator is interposed between the first electrode and the second electrode. The stack, in which the first electrode, the separator, the second electrode, and the separator are stacked in this order at least once, is wound up to form the electrode assembly 1, based on a winding center C extending along the width direction of the first electrode and the second electrode, i.e., along the height direction of the electrode assembly 1 (parallel to the Z-axis).

[0075] The first electrode and / or the second electrode may include a non-coated portion and a coated portion. Here, the coated portion means an active material portion coated with an active material layer. In the electrode assembly 1 of the present invention, the first electrode, the second electrode and a separator interposed therebetween may be wound around a winding shaft to define a core and an outer circumferential surface. The first electrode includes an active material portion coated with an active material layer along the winding direction and a first non-coated portion 10 not coated with the active material layer, and at least a portion of the first non-coated portion 10 may be used as an electrode tab. Meanwhile, the second electrode includes an active material portion coated with an active material layer along the winding direction and a second non-coated portion not coated with the active material layer, and at least a portion of the second non-coated portion may be used as an electrode tab.

[0076] More specifically, the first electrode includes a first conductive substrate and a first electrode active material applied on one or both sides of the first conductive substrate. A first non-coated portion 10, to which the first electrode active material is not applied, is present at one end of the first conductive substrate in a width direction (parallel to the Z-axis). The first non-coated portion 10 functions as a first electrode tab. The first non-coated portion 10 is provided at an upper portion in a height direction (parallel to the Z-axis) of an electrode assembly accommodated in a battery housing. A first coated portion 20, to which the first electrode active material is applied, is present on the opposite side of the non-coated portion of the first conductive substrate.

[0077] Meanwhile, although not shown, the second electrode includes a second conductive substrate and a second electrode active material applied to one or both sides of the second conductive substrate. A second non-coated portion, to which the second electrode active material is not applied, exists at the other end in the width direction of the second conductive substrate. The second non-coated portion functions as a second electrode tab. The second non-coated portion is provided at a lower portion in the height direction of the electrode assembly accommodated in the battery housing. A second coated portion, to which the second electrode active material is applied, exists on the opposite side of the non-coated portion of the second conductive substrate.

[0078] 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.

[0079] In one example, the positive electrode active material is represented by the general chemical formula A[A x M y ]O 2+z (A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected to maintain the compound electrically neutral).

[0080] In other examples, the positive electrode active material is an alkali metal compound xLiM disclosed in US6,677,082, US6,680,143, etc. 1 O 2- (1-x)Li2M 2 O3 (where M 1 contains at least one or more elements having an average oxidation state of 3; M 2 contains at least one or more elements having an average oxidation state of 4; 0 ≦ x ≦ 1).

[0081] In still other examples, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (where M 1 contains at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, and Al; M 2 contains at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains a halogen group element selectively containing F; 0 < a ≦ 2, 0 ≦ x ≦ 1, 0 ≦ y < 1, 0 ≦ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality.), or it can be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg, and Al].

[0082] Desirably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0083] For example, the negative electrode active material may be a carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound, etc. Metal oxides such as TiO2 and SnO2 having a potential of less than 2 V may also be used as the negative electrode active material. Low crystalline carbon, high crystalline carbon, etc. may all be used as the carbon material.

[0084] 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., which may be used alone or in combination. 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.

[0085] At least one surface of the separation membrane may include a coating layer of inorganic particles. The separation membrane itself may also 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.

[0086] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0087] The electrolyte is A + B - In this case, the salt may have the structure:+ Li + , Na + , K + and combinations of these cations. - F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion includes one or more anions selected from the group consisting of:

[0088] The electrolyte may be dissolved in an organic solvent. Examples of the organic solvent include 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, and mixtures thereof.

[0089] In the electrode assembly 1 of the present invention, the first electrode and the second electrode extend in opposite directions to each other along the height direction of the electrode assembly 1 (direction parallel to the Z-axis).

[0090] The structure of the first electrode will be specifically described below. However, this is merely an example, and the structure of the first electrode described below can be applied to both the first electrode and the second electrode, or can be applied only to the second electrode.

[0091] 1 to 3, the first uncoated portion 10 includes a plurality of impregnation slits 10a. The first uncoated portion 10 may further include a plurality of incision lines 10b and segment pieces 10c partitioned by the incision lines 10b.

[0092] The impregnation slits 10a may be formed by, for example, punching using a die or laser notching. The impregnation slits 10a may be formed in a circumferential direction of the electrode assembly 1, i.e., along the winding direction of the electrode assembly 1. In this case, the longitudinal extensions of the impregnation slits 10a adjacent to each other along the circumferential direction may not overlap each other. That is, the longitudinal extensions of the impregnation slits 10a may be disposed approximately parallel to each other.

[0093] 1, 2a, and 2b, the longitudinal extensions of the impregnation slits 10a may extend in a direction substantially parallel to the circumferential direction. For example, the circumferential length of the impregnation slits 10a may be longer than the length of the impregnation slits 10a in the winding axis direction.

[0094] In one aspect of the present invention, referring to Fig. 2b, the impregnation slits 10a adjacent to each other along the circumferential direction among the plurality of impregnation slits 10a may not be formed on the same line but may be provided at offset positions. In other words, the impregnation slits 10a adjacent to each other along the circumferential direction among the plurality of impregnation slits 10a may not be formed on the same line but may be provided at different heights in the winding axis direction. That is, the impregnation slits 10a adjacent to each other along the circumferential direction among the plurality of impregnation slits 10a may be spaced apart at a predetermined interval in a direction parallel to the winding axis of the electrode assembly 1. As a result, the longitudinal extensions of the impregnation slits 10a adjacent to each other along the circumferential direction do not overlap each other.

[0095] With the above-mentioned structure, the strength of the first non-coated portion 10 can be ensured at a certain level in the present invention. For example, when a plurality of impregnation slits 10a extending in a direction parallel to the circumferential direction are formed on the same line, the strength of the first non-coated portion 10 at the position where the plurality of impregnation slits 10a are formed may be very weak. That is, the area of ​​the cross section of the first non-coated portion 10 cut in a direction perpendicular to the winding axis of the electrode assembly 1 (direction parallel to the XY plane) at the position where the impregnation slits 10a are formed is reduced. As a result, the first non-coated portion 10 may be damaged by impact, vibration, etc. applied during the use of the battery, which may cause safety problems such as poor battery performance and / or fire due to an internal short circuit.

[0096] In contrast, according to the present invention, the impregnation slits 10a adjacent to each other in the circumferential direction are not formed on the same line but are provided at offset positions. More specifically, as shown in FIG. 1, the impregnation slits 10a adjacent to each other in the circumferential direction may be spaced apart at a predetermined interval in a direction parallel to the winding axis of the electrode assembly 1. With this structure, the first non-coated portion 10 can minimize the reduction in the area of ​​a cross section at the position where the impregnation slits 10a are formed, i.e., a cross section cut along a direction perpendicular to the winding axis of the electrode assembly 1 (direction parallel to the XY plane). This can improve the tensile strength of the first non-coated portion 10 in the winding axis direction (direction parallel to the Z axis). Therefore, in this case, even if an external force is applied to the first non-coated portion 10, the first non-coated portion 10 is not easily broken.

[0097] In another aspect of the present invention, the longitudinal extension lines of the impregnation slits 10a located on the left and right sides of any one of the impregnation slits 10a may overlap each other. For example, referring to FIG. 2b, the longitudinal extension line of the impregnation slit 10a located on the left side of any one of the impregnation slits 10a and the longitudinal extension line of the impregnation slit 10a located on the right side of any one of the impregnation slits 10a may be the same line. In this manner, the impregnation slits 10a may overlap each other when the first electrode is wound up due to the structure in which the impregnation slits 10a are provided on the same line. As a result, an impregnation path IP may be provided along the radial direction of the electrode assembly 1.

[0098] In yet another aspect of the present invention, referring to FIG. 2b, the interval between adjacent impregnation slits 10a in the circumferential direction may be constant. Alternatively, referring to FIG. 2d as another embodiment, the interval between adjacent impregnation slits 10a in the circumferential direction may gradually increase from the core side to the outer periphery side of the electrode assembly 1. More specifically, referring to FIG. 2d, the sheet-shaped first electrode and / or second electrode has a structure that is wound in one direction. In this case, a plurality of impregnation slits 10a may be provided along the circumferential direction. The interval between the impregnation slits 10a may be relatively close on the core side of the first electrode and / or second electrode, and may be configured to gradually increase as it progresses toward the outer periphery side. This is because the radius of the electrode assembly 1 increases as the first electrode and / or second electrode is wound in one direction, and the length of the circumference formed by the layers constituting the electrode assembly 1 increases as it progresses toward the outer periphery side. That is, the size of the circumference of the outermost layer gradually increases as the first electrode and / or the second electrode are wound in one direction. Therefore, when forming the impregnation slits 10a in the sheet-like first electrode and / or the second electrode, if the interval between the impregnation slits 10a is increased toward the outer periphery, the impregnation slits 10a in the previous layer and the impregnation slits 10a in the next layer are more likely to face each other, and therefore the impregnation path IP along the radial direction of the electrode assembly 1 is more likely to be provided. That is, according to such a structure of the present invention, the impregnation path IP can be effectively provided. As a result, the impregnation characteristics of the electrolyte in the center of the electrode of the electrode assembly 1 can be improved.

[0099] In one aspect of the present invention, referring to Fig. 2b, the circumferential length of the impregnation slit 10a may be constant. Alternatively, referring to Fig. 2e as another embodiment, the circumferential length of the impregnation slit 10a may gradually increase from the core side to the outer periphery side of the electrode assembly 1. Thus, the width of the impregnation path IP may gradually increase as it proceeds toward the outer periphery side of the electrode assembly 1.

[0100] According to this structure, the impregnation slit 10a in the previous layer and the impregnation slit 10a in the next layer are more likely to face each other, so that the impregnation path IP is more likely to be provided. In addition, since the area of ​​the impregnation slit 10a in the outermost layer, which is the portion where the electrolyte starts to be impregnated into the electrode assembly 1, is large, the electrolyte can be smoothly impregnated into the inside of the electrode assembly 1. In addition, since the area of ​​the impregnation slit 10a on the core side is small, the reduction in the area of ​​the cross section cut along the direction perpendicular to the winding axis of the electrode assembly 1 (direction parallel to the XY plane) can be minimized. As a result, the tensile strength of the first non-coated portion 10 in the winding axis direction (direction parallel to the Z axis) can be improved.

[0101] FIG. 2b is a diagram for explaining the first and second lines, and FIG. 2c is a diagram for explaining the first, second and third lines.

[0102] 2b and 2c, the first non-coated portion 10 may include a first line L1, which is a virtual straight line spaced a first distance from the active material and parallel to the boundary between the active material portion and the first non-coated portion 10, and a second line L2, which is a virtual straight line spaced a second distance from an end of the incision line 10b and parallel to the boundary between the active material portion and the first non-coated portion 10. Here, the impregnation slits 10a may be provided on at least one of the first line L1 and the second line L2. Preferably, the impregnation slits 10a may be provided alternately on the first line and the second line along the circumferential direction of the electrode assembly 1. In particular, the impregnation slits 10a located on different lines may not overlap each other in the winding axis direction. For example, referring to Fig. 2b, the impregnation slits 10a located on the first line L1 do not overlap with the impregnation slits 10a located on the second line L2 in the winding axis direction. If the impregnation slits 10a located on the first line L1 and the impregnation slits 10a located on the second line L2 overlap in the winding axis direction, the cross-sectional area of ​​the first non-coated portion 10 cut along the winding axis direction would be reduced, resulting in a decrease in the strength of the first non-coated portion 10.

[0103] In another aspect of the present invention, the circumferential length of the impregnation slits 10a located on the same line may gradually increase from the core side to the outer periphery side of the electrode assembly 1. For example, referring to FIG. 2e, the circumferential length of the impregnation slits 10a located on the first line L1 may be configured to gradually increase as it progresses toward the outer periphery side. Similarly, the circumferential length of the impregnation slits 10a located on the second line L2 may be configured to gradually increase as it progresses toward the outer periphery side. With this structure, the impregnation slits 10a provided in the previous layer and the impregnation slits 10a provided in the next layer are more likely to face each other, so that the impregnation path IP can be smoothly provided.

[0104] In yet another aspect of the present invention, the intervals between the impregnation slits 10a located on the same line may gradually increase from the core side to the outer periphery side of the electrode assembly 1. For example, referring to FIG. 2d, the intervals between the impregnation slits 10a located on the first line L1 may be configured to gradually increase as they move toward the outer periphery side. Similarly, the intervals between the impregnation slits 10a located on the second line L2 may be configured to gradually increase as they move toward the outer periphery side. With this structure, the impregnation slits 10a provided in the previous layer and the impregnation slits 10a provided in the next layer are more likely to face each other, making it possible to smoothly provide an impregnation path IP.

[0105] In still another aspect of the present invention, the first non-coated portion 10 may further include at least one intermediate line Ln, which is a virtual straight line located between the first line L1 and the second line L2, parallel to the first line L1 and the second line L2, and spaced apart from the first line L1 and the second line L2 by a predetermined distance. For example, referring to FIG. 2c, a third line L3 may be provided between the first line L1 and the second line L2. However, the present invention is not limited to this, and a fourth line, a fifth line, etc. may be further provided. That is, the present invention is not limited to the number of lines. That is, the intermediate lines Ln may be plural. Here, the impregnation slit 10a may be provided on at least one of the plurality of intermediate lines Ln. An intermediate impregnation slit 10a may be provided on the intermediate line Ln. Preferably, the impregnation slits 10a may be provided alternately on the plurality of intermediate lines Ln along the circumferential direction. For example, referring to Fig. 2c, the impregnation slits 10a may be provided in the following order from the left: first line L1, second line L2, third line L3, second line L2, first line L1. However, the order of provision is not limited thereto, and it is within the scope of the present invention as long as adjacent impregnation slits 10a in the circumferential direction are not formed on the same line.

[0106] In yet another aspect of the present invention, the impregnation slits 10a provided in the first line L1 and the second line L2 may be arranged with a rule independent of each other. For example, the impregnation slits 10a provided in the first line L1 may be arranged with a certain rule. Also, the impregnation slits 10a provided in the second line L2 may be arranged with a certain rule. However, the impregnation slits 10a provided in the first line L1 and the impregnation slits 10a provided in the second line L2 may be arranged independently in principle without affecting each other. However, as an exception, it is preferable that the impregnation slits 10a provided in the first line L1 and the impregnation slits 10a provided in the second line L2 do not overlap in the winding axis direction. If the impregnation slits 10a in the first line L1 and the impregnation slits 10a in the second line L2 overlap in the direction of the winding axis, the cross-sectional area of ​​the non-coated portion cut along the winding axis will be excessively reduced, resulting in a decrease in the strength of the non-coated portion.

[0107] In another aspect of the present invention, the number of the impregnation slits 10a on each imaginary line is preferably approximately the same. In other words, the number of the impregnation slits 10a on the first line L1, the second line L2, and at least one intermediate line Ln may be approximately the same. For example, referring to FIG. 2c, if the total number of the impregnation slits 10a on the first non-coated portion 10 is 30, the number of the impregnation slits 10a on the first line L1, the number of the impregnation slits 10a on the second line L2, and the number of the impregnation slits 10a on the third line L3 are preferably about 10 each. This is because, if an exceptionally large number of impregnation slits 10a are formed on only one line, the area of ​​the cross section of the non-coated portion cut along that line may be excessively reduced, resulting in a decrease in the strength of the non-coated portion.

[0108] Referring to FIG. 3, the impregnation slits 10a may be arranged parallel to one another and inclined at a predetermined angle with respect to a line extending along the circumferential direction.

[0109] With this structure, as in the above, it is possible to minimize weakening of the strength of the first non-coated portion 10 due to the formation of the impregnation slits 10a, compared to the case where a plurality of impregnation slits 10a extending in a direction parallel to the circumferential direction are formed on the same line. Also, with this structure, the first non-coated portion 10 has uniform electrolyte impregnation over the entire area in the height direction (direction parallel to the Z-axis).

[0110] On the other hand, in the same manner as the minimization of the reduction in the cross-sectional area at the position where the impregnation slit 10a is formed as described above, the impregnation slit 10a may be arranged to be spaced apart from the incision line 10b described later along the extension direction of the winding shaft (direction parallel to the Z-axis). For example, the interval between the incision line 10b and the impregnation slit 10a is preferably about 1 mm to 5 mm, more preferably about 2 mm to 3 mm. If the interval between the incision line 10b and the impregnation slit 10a is smaller than about 1 mm, the interval between the incision line 10b and the impregnation slit 10a becomes excessively thin, and the possibility of breakage between the incision line 10b and the impregnation slit 10a increases. On the other hand, if the interval between the incision line 10b and the impregnation slit 10a is larger than about 5 mm, the dead space, which is a wasted space, increases, and the energy density decreases. Therefore, when the distance between the cut line 10b and the impregnation slit 10a is about 1 mm to 5 mm, the possibility of the first non-coated portion 10 being broken due to external forces such as impact and vibration that may be applied during the manufacturing and use of the battery is reduced, and the energy density may be increased.

[0111] In another aspect of the present invention, the first non-coated portion 10 may be located at the upper portion of the electrode assembly 1, and the second non-coated portion may be located at the lower portion of the electrode assembly 1. In this case, the impregnation slit 10a provided in the first non-coated portion 10 is located at the upper portion of the electrode assembly 1. As a result, the electrolyte solution flowing in from the upper portion of the electrode assembly 1 may permeate into the electrode assembly 1 through the impregnation slit 10a formed at the upper portion of the electrode assembly 1, and then smoothly permeate to the central region and the lower region of the electrode assembly 1 due to the influence of gravity. Alternatively, the second non-coated portion located at the lower portion of the electrode assembly 1 may also be provided with an impregnation slit. That is, as described above, for convenience of description, only the case in which the impregnation slit 10a is provided in the first electrode has been described in this specification, but the impregnation slit 10a may be provided only in the second electrode, or in both the first electrode and the second electrode.

[0112] Meanwhile, the first electrode may be a negative electrode, and in this case, the second electrode is a positive electrode. However, the first electrode and the second electrode of the present invention are not limited to a single electrode, and may be reversed.

[0113] 4 is a plan view of the electrode assembly of FIG. 1, and FIG. 5a is a front cross-sectional view of the electrode assembly of FIG.

[0114] 4 and 5a, the first uncoated portion 10 may include a plurality of segment pieces 10c that are spaced apart from each other along the circumferential direction of the electrode assembly 1 and are partitioned by a plurality of incision lines 10b that are formed at a predetermined depth from an end of the first uncoated portion 10. That is, the segment piece 10c is provided at one end of the first uncoated portion 10.

[0115] The segment pieces 10c may be bent in a radial direction of the electrode assembly 1 to cover at least a part of one surface of the electrode assembly 1 perpendicular to the winding shaft. Here, the radial direction means a direction toward the core side or the outer periphery side. For example, referring to Fig. 4 and Fig. 5a, the segment pieces 10c may be bent in a direction toward the core side to cover the entire one surface of the electrode assembly 1 perpendicular to the winding shaft.

[0116] In this manner, the segment piece 10c provided at one end of the first non-coated portion 10 is bent to cover one surface of the electrode assembly 1 perpendicular to the winding axis, thereby ensuring a wide contact area between the first non-coated portion 10 and a current collector (not shown) coupled to one surface of the electrode assembly 1. This may reduce the internal resistance of the battery. Also, the bonding strength between the electrode assembly 1 and the current collector may be improved.

[0117] Meanwhile, after the electrode assembly 1 is housed in a battery housing, the electrolyte may be injected from an opening at the top of the battery housing. At this time, since the plurality of segment pieces 10c cover the entire surface of the electrode assembly 1 perpendicular to the winding axis, the electrolyte may not be smoothly impregnated from the top of the electrode assembly 1. In particular, in the case of a medium- or large-sized battery, the electrolyte may not be impregnated up to the center of the electrode assembly 1.

[0118] Therefore, in the present invention, among the multiple impregnation slits 10a, the impregnation slits 10a adjacent to each other along the radial direction of the electrode assembly 1 are at least partially overlapped to provide an impregnation path IP through which the electrolyte can pass along the radial direction. In this case, the impregnation path IP can be provided from the outer circumferential surface of the electrode assembly 1 to a predetermined depth along the radial direction.

[0119] For example, referring to FIG. 5a, a plurality of segment pieces 10c provided at one end of the first non-coated portion 10 are bent toward the core side to cover the entire surface of the electrode assembly 1 perpendicular to the winding axis. At this time, the impregnation slits 10a adjacent to each other along the radial direction of the electrode assembly 1 are at least partially overlapped with each other to provide an impregnation path IP through which the electrolyte can pass along the radial direction. In FIG. 5a, the impregnation path IP is provided along the radial direction from the outer circumferential surface of the electrode assembly 1 to the winding center C. Therefore, the electrolyte can move to the center of the electrode assembly 1 through the impregnation path IP penetrating the electrode assembly 1. The electrolyte that has flowed into the impregnation path IP can flow downward due to the force of gravity. As a result, the electrode assembly 1 of the present invention can be uniformly impregnated with the electrolyte over its entire area in the height direction (direction parallel to the Z axis) and its entire area in the radial direction.

[0120] FIG. 5b is an enlarged view of a portion of the segment of FIG. 5a.

[0121] 5b, the segment pieces 10c may be overlapped in multiple layers along the radial direction of the electrode assembly 1 to form a curved surface. The curved surface may include a lamination number increasing section in which the number of overlaps of the segment pieces 10c gradually increases to a maximum value from the outer periphery side to the core side of the electrode assembly 1, and a lamination number uniform section from the radial point where the number of overlaps reaches the maximum value to the radial point where the innermost segment piece is present.

[0122] In this case, welding may be performed on a certain region with a current collector (not shown) provided on the bent surface of the first non-coated portion 10. That is, the current collector may be attached to a region where a plurality of segment pieces 10c are overlapped in multiple layers. In particular, the current collector may be attached to the bent surface so as to overlap a section with a uniform number of layers. For example, welding of the current collector and the first non-coated portion 10 may be performed on a region on the bent surface of the first non-coated portion 10 where the number of overlaps of the first non-coated portion 10 is 10 or more. The radial proportion of the section where the number of overlaps is 10 or more may be designed to be 25% or more based on the radius of the electrode assembly excluding the core by adjusting the length of the first non-coated portion 10.

[0123] FIG. 5b is a plan view showing a region of a bent surface in which the first non-coated portion 10 of the first conductive substrate, which is divided into a plurality of segments, is folded from the outer periphery side to the core side to form 10 or more overlapping layers in an electrode assembly having a radius of 22 mm and a core radius of 4 mm included in a battery having a 4680 form factor. In the drawing, the electrode assembly region and the core region where no segments exist are not shown. The height of the segments increases by 1 mm from 3 mm for every 1 mm increase in the radius of the electrode assembly. Then, when the illustrated length of 6 mm, 7 mm, or 8 mm is reached, the height of the segments remains substantially the same thereafter.

[0124] Referring to FIG. 5b, the number of overlaps of the first non-coated portion 10 gradually increases from the outer periphery side to the core side, and the maximum value of the number of overlaps increases as the length of the first non-coated portion 10 increases.

[0125] In one example, when the length of the first non-coated portion 10 is 8 mm, the number of overlaps of the first non-coated portion 10 divided into a plurality of segments increases to 18 in a 7 mm section from the outer circumferential surface of the electrode assembly, and in a further 8 mm section toward the core side, the number of overlaps of the first non-coated portion 10 is maintained at a maximum level of 18, and decreases by 1 to 2 in a radial section adjacent to the core. The height of the segments increases stepwise from 3 mm to 8 mm in a radius section of 7 mm to 12 mm. In the present invention, the uniform number of layers section is defined as a radial section from the radial point where the number of overlaps reaches a maximum value to the point where the innermost segment is located, as shown in FIG. 5b. Therefore, the ratio of the uniform number of layers section in which 10 or more segments 10c of the first non-coated portion 10 overlap is 44.4% (8 / 18) of the radius of the electrode assembly excluding the core (4 mm).

[0126] In another example, when the length of the first non-coated portion 10 is 7 mm, the number of overlaps of the first non-coated portion 10 divided into multiple segments increases to 15 in a section 6 mm from the outer circumferential surface of the electrode assembly, and the number of overlaps of the first non-coated portion 10 is maintained constant at a maximum level of 15 in a section 9 mm toward the core side, and decreases by 1 to 2 in a radius section adjacent to the core. The height of the segments increases stepwise from 3 mm to 7 mm in a radius section of 7 mm to 11 mm. Therefore, the ratio of the uniform lamination number section in which 10 or more segments 10c of the first non-coated portion 10 are overlapped is 50% (9 / 18) of the radius of the electrode assembly excluding the core (4 mm).

[0127] In yet another example, when the length of the first non-coated portion 10 is 6 mm, the number of overlaps of the first non-coated portion 10 divided into multiple segments increases to 12 in a 5 mm section from the outer circumferential surface of the electrode assembly, and in a 10 mm section toward the core, the number of overlaps of the first non-coated portion 10 is maintained constant at a maximum level of 12, and decreases by 1 to 2 in the radial section adjacent to the core. The height of the segments increases from 3 mm to 6 mm in a radius section from 7 mm to 10 mm. Therefore, the ratio of the uniform lamination number section in which 10 or more segments 10c of the first non-coated portion 10 are overlapped is 55.6% (10 / 18) of the radius of the electrode assembly excluding the core (4 mm).

[0128] In the present invention, the uniform lamination number section can be increased or decreased depending on the radius of the core, the minimum and maximum values ​​of the segment height in the segment height variable section, and the increase in the segment height in the radial direction of the electrode assembly. Therefore, it is obvious that a person skilled in the art should adjust factors that affect the proportion of the uniform lamination number section to design the proportion to be 25% or more. In one example, if the minimum and maximum values ​​of the segment height in the segment height variable section are both increased, the number of laminations increases and the proportion of the uniform lamination number section can be reduced to the 25% level.

[0129] The uniform lamination number section is an area to which the current collector can be welded. Therefore, by adjusting the ratio of the uniform lamination number section to 25% or more, the weld strength of the current collector can be secured within a desirable range, and this is also advantageous in terms of the resistance of the weld interface.

[0130] According to another aspect of the present invention, when the first uncoated portion 10 has such a folded shape, the space occupied by the first uncoated portion 10 is reduced, thereby improving the energy density. Also, the bonding area between the first uncoated portion 10 and the current collector 30 is increased, thereby improving the bonding strength and reducing the resistance.

[0131] FIG. 6 is a plan view of an electrode assembly having a different configuration from the electrode assembly shown in FIG. 4, and FIG. 7 is a front sectional view of the electrode assembly of FIG.

[0132] 6 and 7, the plurality of segment pieces 10c may be folded in a radial direction of the electrode assembly 1. In particular, the plurality of segment pieces 10c may be folded in a direction toward the core side of the electrode assembly 1 to cover only a portion of one surface of the electrode assembly 1 perpendicular to the winding axis.

[0133] In this case, the length of the first non-coated portion 10 in the region adjacent to the winding center C of the electrode assembly 1 may be different from the length of the first non-coated portion 10 in the region adjacent to the outer circumferential surface of the electrode assembly 1. For example, the length of the first non-coated portion 10 in the region adjacent to the winding center C of the electrode assembly 1 may be shorter than the length of the first non-coated portion 10 in the region adjacent to the outer circumferential surface of the electrode assembly 1. In particular, the first non-coated portion 10 in the region adjacent to the winding center C of the electrode assembly 1 may not be provided with the incision lines 10b and the segment pieces 10c. That is, only the first non-coated portion 10 in the region adjacent to the outer circumferential surface of the electrode assembly 1 may be provided with a plurality of incision lines 10b and segment pieces 10c.

[0134] Therefore, according to this embodiment, the first non-coated portion 10 may not be folded and may be open upward in the region adjacent to the winding center C of the electrode assembly 1. Hereinafter, the region not covered upward by the segment piece 10c is referred to as the first region A1. In this case, the radial length of the first region A1 is defined as D1.

[0135] Meanwhile, the segments 10c of the first non-coated portion 10 in the region adjacent to the outer circumferential surface of the electrode assembly 1 may be bent toward the core side to cover only a part of one surface of the electrode assembly 1 perpendicular to the winding shaft. Hereinafter, the region covered upward by the segments 10c in this manner is referred to as the second region A2. In this case, the radial length of the second region A2 is defined as D2.

[0136] According to this structure, the first area A1 is not covered by the segment piece 10c and is open upward, so that the electrolyte solution flowing in from the opening at the top end of the battery housing can smoothly flow into the first area A1, thereby improving the impregnation of the electrolyte solution.

[0137] However, in this case, the impregnation rate of the second region A2 may be somewhat lower than that of the first region A1. Therefore, it is necessary to improve the impregnation rate of the second region A2. In this way, the present invention can form the formation depth P of the impregnation path IP to be greater than or equal to the radial length of the region covered by the segment piece 10c on one surface of the electrode assembly 1 perpendicular to the winding axis. That is, referring to FIG. 7, the formation depth P of the impregnation path IP can be formed to be greater than or equal to the radial length D2 of the second region A2.

[0138] According to this structure, the electrolyte may move through the impregnation path IP to at least the boundary between the second region A2 and the first region A1. Alternatively, the electrolyte may move beyond the second region A2 to the first region A1. Thereafter, the electrolyte may flow downward due to the force of gravity. This allows the electrode assembly 1 of the present invention to be uniformly impregnated with the electrolyte even in its interior.

[0139] Meanwhile, as mentioned above, for convenience of description, this specification has only described the case where the first electrode has the incision line 10b and segment piece 10c, but it goes without saying that such incision line 10b and segment piece 10c may be provided only on the second electrode, or on both the first electrode and the second electrode.

[0140] <Impregnation and durability test> The electrolyte impregnation of the electrode assembly of the present invention was evaluated, and a drop test and a vibration test were also performed to evaluate the strength of the non-coated portion.

[0141] 1) Electrolyte impregnation evaluation An electrode assembly having an impregnation slit for impregnating the electrolyte is fabricated. The electrode assembly is then inserted into a battery housing through an opening at the top, and the electrolyte is injected into the battery housing. After the electrolyte is injected, the battery housing is aged for 24 hours, and the impregnation level of the electrolyte is analyzed. ◯ (Pass): No unimpregnated areas present. × (Fail): Unimpregnated areas present.

[0142] 2) Strength evaluation of non-coated parts (drop test) After welding the electrode assembly and the current collector, they were inserted into the battery housing to manufacture the battery.Then, the battery, which was charged to 4.2V, was dropped from a height of 1.0m onto a wooden floor, and the battery was checked for internal short circuit and / or fire. 〇 (Pass): No short circuit and / or fire inside the battery × (Fail): Short circuit and / or fire occurs inside the battery

[0143] 3) Strength evaluation of non-coated parts (vibration test) After welding the electrode assembly and the current collector, they are placed in a battery housing to manufacture the battery. The battery is then charged to 4.2V and vibrated. The vibration method is 7Hz⇔200Hz, with the vibration frequency changed every 15 minutes, and repeated 12 times in each direction of the X-axis, Y-axis, and Z-axis. After the vibration test is completed, the battery is checked for the occurrence of internal short circuits and / or fires. 〇 (Pass): No short circuit and / or fire inside the battery × (Fail): Short circuit and / or fire occurs inside the battery

[0144] Example 1 The electrode assembly was manufactured so that the impregnation slits adjacent to each other in the circumferential direction among the plurality of impregnation slits were not formed on the same line but were provided at offset positions (zigzag type).

[0145] Comparative Example 1 An electrode assembly was fabricated under the same conditions as in Example 1, except that no impregnation slit was provided.

[0146] Comparative Example 2 An electrode assembly was fabricated under the same conditions as in Example 1, except that a plurality of impregnation slits were formed on the same line along the circumferential direction.

[0147] For each electrode assembly obtained as described above, the impregnation of the electrolyte and the strength of the non-coated portion were evaluated. The results are shown in Table 1.

[0148] [Table 1]

[0149] From the above table the following can be ensured:

[0150] In Example 1, the electrolyte impregnation was excellent, and there was no unimpregnated area in the electrode assembly. In addition, the electrode assembly of Example 1 passed the drop test and the vibration test, which shows that the non-coated part had excellent strength.

[0151] In Comparative Example 1, since no impregnation slits were provided, impregnation with the electrolyte was poor, and there were unimpregnated areas in the electrode assembly.

[0152] In Comparative Example 2, the impregnation slits were provided on the same line along the circumferential direction of the electrode assembly, so the electrolyte impregnation was satisfactory, but the strength of the non-coated portion could not be ensured. Specifically, the electrode assembly of Comparative Example 2 was damaged in part of the non-coated portion as a result of a drop test and a vibration test. That is, the electrode assembly of Comparative Example 2 had low strength of the non-coated portion, and the quality and safety of the battery could not be ensured.

[0153] Meanwhile, battery B including the electrode assembly 1 of the present invention has a structure in which resistance is minimized by expanding the contact area between components, multiplying the current paths, minimizing the length of the current paths, etc. After the product is completed, the AC resistance of battery B measured by a resistance meter between the positive and negative electrodes may be 0.5mΩ to 4mΩ, which is suitable for fast charging, and preferably 1mΩ to 4mΩ.

[0154] In the present invention, the battery may be, for example, a battery having a form factor ratio (defined as the value obtained by dividing the diameter of the battery by the height, i.e., the ratio of the diameter Φ to the height H) of greater than about 0.4. Here, the form factor refers to a value indicating the diameter and height of the battery.

[0155] Preferably, the cylindrical battery has a diameter of 40mm to 50mm and a height of 60mm to 130mm. The battery according to an embodiment may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the number indicating the form factor, the first two digits indicate the diameter of the battery, and the next two digits indicate the height of the battery.

[0156] Recently, as batteries are applied to electric vehicles, the form factor of the battery is increasing beyond the traditional 1865, 2170, etc. The increase in form factor brings increased energy density, increased safety against thermal runaway, and improved cooling efficiency.

[0157] The energy density of the battery can be further increased when the form factor is increased and the wasted space inside the battery housing is minimized. The battery according to the present invention has an optimal structure that can increase the capacity of the battery and reduce the resistance while improving the electrolyte impregnation of the electrode current collector.

[0158] A battery according to one embodiment of the present invention may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0159] Another embodiment of the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0160] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436.

[0161] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0162] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0163] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. have been used. In the case of an 1865 battery, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is about 0.277. In the case of a 2170 battery, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is about 0.300.

[0164] The electrode assembly 1 according to the embodiment of the present invention may be included in a battery B. Referring to Fig. 8, the wound electrode assembly 1 is accommodated in a battery housing of the battery B. The battery B according to the embodiment of the present invention is included in a battery pack 3, and the battery pack 3 may be mounted on an automobile V. Referring to Fig. 9, the battery pack 3 according to an embodiment of the present invention includes an assembly of secondary batteries in which a plurality of batteries B according to an embodiment of the present invention are electrically connected as described above, and a pack housing 2 that accommodates the secondary batteries. In the drawings of the present invention, components such as bus bars for electrical connection, a cooling unit, and power terminals are omitted for ease of illustration.

[0165] 10, a vehicle V according to an embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and may include a battery pack 3 according to an embodiment of the present invention. The vehicle V operates by receiving power from the battery pack 3 according to an embodiment of the present invention.

[0166] Although terms indicating directions such as up and down are used in this specification, these terms are used merely for convenience of explanation, and it will be obvious to those skilled in the art that these terms may change depending on the position of the object of interest, the position of the observer, etc.

[0167] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by those having ordinary skill in the art to which the present invention pertains within the scope of the technical spirit of the present invention and the scope of the claims. [Explanation of symbols]

[0168] 1 Electrode assembly 10 First non-coated section 10a Impregnation slit 10b Incision line 10c segmental piece 20 First Coating Section IP impregnation route P: Depth of impregnation path C Winding center A1 1st area A2 2nd area D1 Radial length of the first region D2 Radial length of the second region B. Battery 2 Pack Housing 3 Battery pack V Automobile

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound around a winding shaft to define a core and an outer circumferential surface, the first electrode includes an active material portion coated with an active material layer along a winding direction and a first non-coated portion not coated with an active material layer, at least a portion of the first non-coated portion being used as an electrode tab; the first non-coated portion includes a plurality of impregnation slits formed along a circumferential direction of the electrode assembly, The longitudinal extension lines of the impregnation slits adjacent to each other along the circumferential direction do not overlap each other, The adjacent impregnation slits are not overlapped with each other on the same straight line in the winding axial direction, An electrode assembly, wherein a circumferential length of the impregnation slit is longer than a length of the impregnation slit in a winding axis direction.

2. The plurality of impregnation slits are The electrode assembly according to claim 1 , wherein the electrode assembly has a shape extending in a direction parallel to the circumferential direction.

3. 3. The electrode assembly according to claim 2, wherein the impregnation slits adjacent to each other in the circumferential direction among the plurality of impregnation slits are not formed on the same line but are provided at different heights in the winding axis direction.

4. 3. The electrode assembly according to claim 2, wherein the impregnation slits adjacent to each other along the circumferential direction among the plurality of impregnation slits are spaced apart at a predetermined interval in a direction parallel to a winding shaft of the electrode assembly.

5. 5. The electrode assembly according to claim 1, wherein the longitudinal extensions of the impregnation slits on the left and right sides of any one of the impregnation slits overlap each other.

6. 6. The electrode assembly according to claim 1, wherein the intervals between adjacent impregnation slits in the circumferential direction are constant.

7. 7. The electrode assembly according to claim 1, wherein the interval between adjacent impregnation slits in the circumferential direction gradually increases from a core side to an outer periphery side of the electrode assembly.

8. 8. The electrode assembly according to claim 1, wherein the impregnation slit has a constant circumferential length.

9. 8. The electrode assembly according to claim 1, wherein a circumferential length of the impregnation slit gradually increases from a core side to an outer periphery side of the electrode assembly.

10. The electrode assembly according to claim 1 , wherein the plurality of impregnation slits are inclined at a predetermined angle with respect to a line extending along the circumferential direction.

11. The electrode assembly according to claim 10, wherein the plurality of impregnation slits are parallel to each other.

12. 11. The electrode assembly according to claim 1, wherein among the plurality of impregnation slits, adjacent impregnation slits in a radial direction of the electrode assembly at least partially overlap each other to provide an impregnation path through which an electrolyte can pass in the radial direction.

13. The impregnation path is The electrode assembly according to claim 12, wherein the electrode is provided to a predetermined depth in the radial direction from an outer circumferential surface of the electrode assembly.

14. The first non-coated portion is 14. The electrode assembly according to claim 1, further comprising a plurality of segmented pieces separated from each other along a circumferential direction of the electrode assembly and partitioned by a plurality of incision lines formed from an end of the first non-coated portion to a predetermined depth.

15. The plurality of segment pieces are The electrode assembly is folded in multiple layers along a radial direction to form a bent surface, 15. The electrode assembly of claim 14, wherein the bent surface includes a lamination number increasing section in which the number of overlaps of the segment pieces gradually increases from the outer periphery side to the core side of the electrode assembly to a maximum value, and a lamination number uniform section from a radius point where the number of overlaps becomes maximum to a radius point where an innermost segment piece is present.

16. The plurality of segment pieces are The electrode assembly is bent in a radial direction, The electrode assembly according to claim 14, wherein the electrode assembly is provided with a surface perpendicular to the winding axis, the surface being at least partially covered.

17. The plurality of segment pieces are The electrode assembly is bent in a radial direction, The electrode assembly according to claim 14, wherein the electrode assembly has a surface perpendicular to the winding axis and the surface is entirely covered.

18. Among the plurality of impregnation slits, the impregnation slits adjacent to each other along the radial direction of the electrode assembly are 16. The electrode assembly of claim 15, wherein the electrodes overlap at least partially to provide an impregnation path along the radial direction through which electrolyte can pass.

19. The impregnation path is The electrode assembly according to claim 18, wherein the electrode assembly is provided to a predetermined depth along the radial direction from an outer circumferential surface of the electrode assembly.

20. The depth of the impregnation path is 20. The electrode assembly of claim 19, wherein the radial length of the area covered by the segment on a surface of the electrode assembly perpendicular to the winding axis is greater than or equal to the radial length of the area covered by the segment on a surface of the electrode assembly perpendicular to the winding axis.

21. The first non-coated portion is a first line that is a virtual straight line that is spaced a first distance from the active material portion and is parallel to a boundary line between the active material portion and the first non-coating portion; a second line that is a virtual straight line that is spaced a second distance from an end of the cut line and is parallel to a boundary line between the active material portion and the first non-coated portion; Including, The electrode assembly according to claim 14 , wherein the impregnation slit is provided on at least one of the first line and the second line.

22. The electrode assembly of claim 21, wherein the impregnation slits are provided on the first line and the second line in a circumferential direction of the electrode assembly.

23. The impregnation slits located on different lines are The electrode assembly according to claim 21, wherein the electrodes do not overlap each other in the winding axial direction.

24. The circumferential length of the impregnation slits located on the same line is The electrode assembly of claim 21, wherein the thickness gradually increases from a core side to an outer periphery side of the electrode assembly.

25. The intervals between the impregnation slits located on the same line are: The electrode assembly of claim 21, wherein the thickness gradually increases from a core side to an outer periphery side of the electrode assembly.

26. The first non-coated portion is At least one intermediate line is located between the first line and the second line, is parallel to the first line and the second line, and is a virtual straight line spaced apart from the first line and the second line by a predetermined distance; The electrode assembly according to claim 24, further comprising an intermediate impregnation slit provided on the intermediate line.

27. 27. The electrode assembly according to claim 26, wherein the intermediate lines are multiple, and the intermediate impregnation slits are provided alternately on the multiple intermediate lines along a circumferential direction.

28. The electrode assembly according to claim 26, wherein the number of the impregnation slits provided on the first line, the second line and the at least one intermediate line is the same.

29. 29. The electrode assembly according to claim 14, wherein the incision line and the impregnation slit are spaced apart from each other by a predetermined distance.

30. The electrode assembly according to claim 29, wherein the distance between the incision line and the impregnation slit is 1 mm to 5 mm.

31. The electrode assembly of claim 1 , wherein the first non-coated portion is located on an upper portion of the electrode assembly.

32. The electrode assembly of claim 31 , wherein the first electrode is a negative electrode.

33. the second electrode includes an active material portion coated with an active material layer along a winding direction and a second non-coated portion not coated with an active material layer, at least a portion of the second non-coated portion being used as an electrode tab; the second non-coated portion includes a plurality of impregnation slits formed along a circumferential direction of the electrode assembly, 33. The electrode assembly according to claim 1, wherein the longitudinal extensions of the impregnation slits adjacent to each other along the circumferential direction do not overlap each other.

34. A battery comprising an electrode assembly according to any one of claims 1 to 33.

35. A battery pack comprising at least one battery according to claim 34.

36. 36. A motor vehicle comprising the battery pack of claim 35.

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