Electrode assembly, cylindrical battery cell, battery pack including the same, and automobile

Abstract

The electrode assembly 1 is obtained by winding up a first electrode 2, a first separator 3, a second electrode 4, and a second separator 3 in a stacked state in a longitudinal direction and winding up the stacked electrodes in a cylindrical shape around a winding center, the electrode assembly having an active material applied to both surfaces of the first electrode 2 to form a first electrode coated portion, a first electrode uncoated portion 21 where no active material is applied at one axial (width) end of the first electrode 2, an active material applied to both surfaces of the second electrode 4 to form a second electrode coated portion 42, and a second electrode uncoated portion 41 where no active material is applied at the other axial (width) end of the second electrode 4, and an insulating coating layer 45 is formed by coating a predetermined section from a boundary between the second electrode coated portion 42 and the second electrode uncoated portion 41 toward an end of the second electrode uncoated portion 41 with an insulating material.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0168017 filed on November 30, 2021, and Korean Patent Application No. 10-2022-0051015 filed on April 15, 2022, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly, a cylindrical battery cell, and a battery pack and a vehicle including the same. [Background technology]

[0003] In a cylindrical secondary battery, in order to maximize current collection efficiency, a battery can may employ a jelly-roll type electrode assembly having positive and negative electrode tabs extending upward and downward along the height direction.

[0004] As shown in Fig. 1, the jelly roll-type electrode assembly wound around the winding center has a first electrode uncoated region 21 exposed at one axial end and a second electrode uncoated region 41 exposed at the other axial end. Here, the description will be given assuming that the first electrode 2 is a positive electrode and the second electrode 4 is a negative electrode. However, the reverse case can also be applied.

[0005] In recent years, a battery structure has been developed in which the exposed plain area at the end is bent radially to form a flat surface, as shown in Figure 2, and a current collector plate 6 is welded onto the bent plain area, as shown in Figure 3.

[0006] However, during the process of applying pressure to weld the second electrode current collector plate 6 onto the bent second electrode uncoated portion 41, the base end of the second electrode uncoated portion 41 may buckle, as shown in Fig. 4. Even if a separator 3 is interposed between the first electrode 2 and the second electrode 4, such buckling may cause the second electrode uncoated portion 41 to come into contact with the adjacent first electrode 2, potentially causing a short circuit.

[0007] Additionally, during the process of welding the second electrode uncoated portion 41 to the second electrode current collector plate 6, welding heat may reach the separator of the electrode assembly and cause deformation of the separator.

[0008] In a cylindrical secondary battery, the protruding positive electrode terminal in the center faces upward and the can serves as the negative electrode. Therefore, the positive electrode tab connected to one axial end of the jelly-roll electrode assembly faces upward continuously not only in a distribution environment but also in a usage environment.

[0009] Conversely, this can be said to mean that the other axial end always faces the bottom. Therefore, second electrode uncoated portion 41 is continuously subjected to an axial load not only during the process of applying pressure to weld second electrode uncoated portion 41 but also during use. In particular, since the axial load applied during use acts on second electrode uncoated portion 41, which is bent and welded, the portion of second electrode uncoated portion 41 that extends in the axial direction and is located inside the bent portion is particularly vulnerable to buckling deformation.

[0010] Furthermore, the risk of buckling exists regardless of whether the connection method on the positive electrode side is a method of bending and welding the first electrode uncoated portion 21 or a method of using the electrode tab 7. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been devised to solve the above-mentioned problems, and aims to provide an electrode assembly in which the strength of the base end of the uncoated portion is ensured so that the base end of the uncoated portion does not buckle when the uncoated portion is axially compressed by the current collector plate, and a battery cell using the electrode assembly.

[0012] An object of the present invention is to provide an electrode assembly and a battery cell using the same that can prevent a separator from being deformed even if buckling occurs at a base end of an uncoated portion when the uncoated portion is axially compressed by a current collector plate.

[0013] The present invention aims to provide an electrode assembly in which buckling occurs at the base end of the uncoated portion when the uncoated portion is axially compressed by a current collector plate, and a battery cell using the electrode assembly is provided in which a short circuit does not occur even if the buckled uncoated portion comes into contact with an electrode of the opposite polarity.

[0014] SUMMARY OF THE INVENTION An object of the present invention is to provide an electrode assembly having buckling resistance even when an uncoated portion is continuously subjected to a load due to the weight of the battery cell, and a battery cell using the electrode assembly.

[0015] An object of the present invention is to provide an electrode assembly that can prevent a separator from being damaged or deformed by heat generated when welding a folded uncoated portion, and a battery cell using the same.

[0016] The technical object of the present invention is not limited to the above-mentioned objects, and other unmentioned objects and advantages of the present invention can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it is clear that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0017] The present invention can be applied to an electrode assembly 1 in a form in which the first electrode 2 and the second electrode 4 are stacked with a separator 3 interposed therebetween, and the first electrode 2, the second electrode 4, and the separator 3 are wound up. The first electrode 2 can include a first electrode coating portion 22, which is a region where a first active material 23 is applied to the surface of a first electrode foil 20, and the second electrode 4 can include a second electrode coating portion 42, which is a region where a second active material 46 is applied to the surface of a second electrode foil 40.

[0018] The second electrode coating portion 42 may have a width in the axial direction that is wider than that of the first electrode coating portion 22. Thus, both axial end portions of the second electrode coating portion 42 may be disposed to extend further outward in the axial direction than both axial end portions of the first electrode coating portion 22.

[0019] The second electrode 4 may have a second electrode uncoated portion 41, which is a region where no active material is applied, at one end in the axial direction (width direction) of the second electrode 4. The boundary between the second electrode coated portion 42 and the second electrode uncoated portion 41 may be located further inward in the axial direction than the end of the separator 3 in the axial direction.

[0020] The thickness of the second electrode 4 may be even thinner than the thickness of the first electrode 2 .

[0021] The rigidity of the material of the second electrode 4 may be even lower than the rigidity of the material of the first electrode 2 .

[0022] The first electrode 2 may constitute a positive electrode, and the second electrode 4 may constitute a negative electrode.

[0023] The first electrode 2 may include a first electrode uncoated portion 21, which is a region where no active material is applied, at the other axial end of the first electrode 2.

[0024] The buckling resistance of the second electrode uncoated portion 41 may be lower than the buckling resistance of the first electrode uncoated portion 21 .

[0025] The axial length of the second electrode uncoated region 41 may be longer than the axial length of the first electrode uncoated region 21 .

[0026] The first electrode 2 may include an electrode tab 7 welded to a region not coated with the first active material 23 and protruding from the first electrode 2 toward the other axial side.

[0027] In order to solve the above-mentioned problems, the second electrode 4 of the present invention includes an insulating coating layer 45 in which a predetermined section from the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 toward the end of the second electrode uncoated portion 41 is coated with an insulating material.

[0028] The insulating coating layer 45 may be provided in the form of being coated with an insulating liquid or having an insulating tape attached thereto.

[0029] The insulating coating layer 45 may extend further axially outward beyond the axial end of the separation membrane 3 .

[0030] The insulating coating layer 45 may be thinner than the second electrode coating portion 42. Thus, unlike the second electrode coating portion 42 which is in close contact with the separator 3, the insulating coating layer 45 may be in light contact with the separator 3 or may be spaced apart from the separator 3.

[0031] When the insulating coating layer 45 covers the boundary between the second electrode coating portion 42 and the second electrode non-coating portion 41 , it may also cover the small section 43 at the end of the second electrode coating portion 42 .

[0032] The thickness of the insulating coating layer 45 in the axial direction may be constant.

[0033] In some sections, the thickness of the insulating coating layer 45 in the axial direction may not be constant.

[0034] The second electrode coating portion 42 adjacent to the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 may have a gliding portion whose thickness gradually decreases toward the boundary. Complementarily, the portion of the insulating coating layer 45 coated on the gliding portion may gradually increase in thickness toward the boundary.

[0035] The second electrode uncoated portion 41 is bent in the radial direction of the electrode assembly 1 at a predetermined bending position (F), and the bending position (F) may be located further outward in the axial direction than the end of the separation membrane 3.

[0036] The insulating coating layer 45 may cover at least a portion of the section from the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 to the bending position (F) of the second electrode uncoated portion 41 .

[0037] The insulating coating layer 45 may not cover the second electrode uncoated portion 41 by a predetermined gap (G) in the axial direction from the bending position (F).

[0038] The second electrode uncoated portion 41 has a notch (N) formed axially inward from its end, and multiple notches (N) may be arranged at a distance from each other along the circumferential direction (longitudinal direction) of the second electrode 4.

[0039] A portion of the second electrode uncoated portion disposed between two circumferentially adjacent notched portions (N) can define a notched tab (T).

[0040] The circumferential length of the notched tab (T) may be constant, or may increase gradually or stepwise from the winding core side to the outer periphery side.

[0041] The second electrode non-coating portion 41 may not have a notched tab (T) in a predetermined section on the core end side and / or a predetermined section on the outer circumferential end side.

[0042] The shape of the notched tab (T) may be a trapezoidal shape that narrows from the base end to the tip end, but the notched tab (T) may have various shapes such as a triangle, a semicircle, a semi-oval, a parallelogram, etc.

[0043] The bending position (F) may be located at the base end of the notched tab (T).

[0044] According to the present invention, at the axial end of the second electrode 4 where the second electrode uncoated portion 41 is exposed, an insulating coating layer 45 is formed by coating a predetermined section from the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 toward the end of the second electrode uncoated portion 41 with an insulating material.

[0045] When covering the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41, the insulating coating layer 45 may also cover a small section at the end of the second electrode coating portion 42. This further reinforces the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 and ensures insulation of the boundary.

[0046] The second electrode uncoated portion 41 may be bent in the centripetal direction of the electrode assembly 1. In this case, the second electrode uncoated portion 41 may be provided with a bending guide structure (N, T) that can guide the second electrode uncoated portion 41 to bend at a predetermined axial position (F).

[0047] The bending guide structure (N, T) may be a structure in which the second electrode uncoated portion 41 is cut in the axial direction from the tip of the second electrode uncoated portion 41 by the axial section in which the second electrode uncoated portion 41 must be bent to form a notch portion (N), thereby segmenting the second electrode uncoated portion 41 into a notch tab (T).

[0048] These folding guide structures (N, T) can guide the folding position (F) of the second electrode non-coating portion 41.

[0049] The insulating coating layer 45 may cover at least a portion of the section from the boundary between the second electrode coating portion 42 and the second electrode non-coating portion 41 to the bending position (F).

[0050] The insulating coating layer 45 may extend further axially outward than the separation membrane 3. This prevents the second electrode uncoated portion 41 from being electrically short-circuited with the adjacent first electrode 2 via the separation membrane 3, even if buckling occurs at the base end of the second electrode uncoated portion 41.

[0051] The insulating coating layer 45 may not completely cover the bending guide structure 47 or the bending position, but may only cover a predetermined gap (G). This prevents stress from being transmitted to the insulating coating layer 45 when bending occurs at the bending position, thereby preventing damage to the insulating coating layer 45 and thus preventing an effect on the buckling resistance of the insulating coating layer 45.

[0052] The notched tab (T) may be bent in a radial direction at a bending position (F). The notched tab (T) may be bent in a centripetal direction. The notched tab (T) may be bent in a centrifugal direction.

[0053] By bending the notched tab (T), the tab surface as viewed in the axial direction may be welded to the second electrode current collector 6. The current collector 6 may be welded to the bottom 301F of the battery can 301C or to the cap 307.

[0054] The tab surface may be welded directly to the bottom 301F of the battery can 301C without a current collector, or may be welded to the cap 307.

[0055] The first electrode uncoated portion 21 provided at the other axial end of the first electrode 2 has a plurality of notches formed in the longitudinal direction, and the portion of the first electrode uncoated portion between these can form a notch tab.

[0056] The notched tab of the first electrode uncoated portion 21 may be bent in the centripetal or centrifugal direction and welded to the first electrode current collector 5. The first electrode current collector 5 may be welded to the electrode terminal 301R.

[0057] The electrode tab 7 of the first electrode 2 may be welded to the electrode terminal 301R. [Effects of the Invention]

[0058] According to the present invention, the base end of the uncoated portion is reinforced by an insulating coating layer, which prevents the base end of the uncoated portion from buckling when the uncoated portion is pressed axially by the current collector plate.

[0059] According to the present invention, even if buckling occurs at the base end of the uncoated portion during the process of axially compressing the uncoated portion with the current collector plate, deformation of the separator can be prevented because the thickness of the insulating coating layer is thinner than that of the electrode coating portion and the insulating coating layer and the separator are spaced apart to a certain extent.

[0060] According to the present invention, even if buckling occurs at the base end of the uncoated portion during the process of applying axial pressure to the uncoated portion with the current collector plate and the buckled uncoated portion comes into contact with an electrode of the opposite polarity, a short circuit will not occur because the base end of the uncoated portion is coated with an insulating coating layer.

[0061] According to the present invention, the insulating coating layer can further shorten the extension length of the separator that extends axially outward from the second electrode coating portion. Therefore, the end of the separator may be positioned axially further inward than the bent portion of the second electrode uncoated portion. This prevents the separator from being deformed by heat generated when welding the bent surface of the second electrode uncoated portion to the second electrode current collector plate or the bottom or cap of the battery can.

[0062] Battery cells equipped with electrode assemblies of this structure are extremely safe, making them highly suitable for use as batteries for electric vehicles that are exposed to continuous vibration and shock.

[0063] According to the present invention, when the second uncoated electrode portions of a jelly-roll electrode assembly are bent radially to overlap adjacent second uncoated electrode portions and a second electrode current collector plate is pressed against the overlap, the base end of the second uncoated electrode portion, reinforced by the insulating coating layer, resists buckling and prevents buckling. Even if buckling does occur in the second uncoated electrode portion, the insulating coating layer covers the buckled portion, preventing a short circuit with the first electrode. This improves the safety of cylindrical secondary batteries.

[0064] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief explanation of the drawings]

[0065] [Figure 1] FIG. 2 is a schematic diagram showing a side view of an electrode assembly wound into a jelly roll. [Figure 2] 2 is a schematic diagram showing a state in which the uncoated portion of the electrode assembly of FIG. 1 is bent in the radial direction to form a flat surface. FIG. [Figure 3] 3 is a view showing a state in which a current collecting plate is pressed in order to weld the current collecting plate to the flat surface shown in FIG. 2. [Figure 4] 10 is a view showing a state in which the base end of the uncoated portion is buckled due to axial pressure. [Figure 5] 1 is a development view of a positive electrode (first electrode) used in an electrode assembly. [Figure 6] 1 is a development view of an embodiment of a negative electrode (second electrode) according to the present invention used in an electrode assembly. [Figure 7] 1 is a view of a stack of a positive electrode, a negative electrode, and a separator, viewed from the axial direction before being wound up. [Figure 8] 8 is a side cross-sectional view of an electrode assembly formed by winding up the laminate of FIG. 7. FIG. [Figure 9] 9 is a side cross-sectional view showing a state in which a negative electrode uncoated portion extending from an axial end of the electrode assembly of FIG. 8 is bent radially inward. [Figure 10]4 is an enlarged view of an embodiment of a negative electrode uncoated portion of an electrode assembly; [Figure 11] 4 is an enlarged view of an embodiment of a negative electrode uncoated portion of an electrode assembly; [Figure 12] 10 is a side cross-sectional view showing a state in which a current collecting plate is welded to the bent uncoated portion of FIG. 9. FIG. [Figure 13] 1 is a development view of another embodiment of a negative electrode according to the present invention; [Figure 14] 14 is a side cross-sectional view of an electrode assembly formed by winding up a laminate to which the negative electrode of FIG. 13 is applied. [Figure 15] 10 is a development view of another embodiment of a positive electrode. [Figure 16] 16 is a side cross-sectional view of an electrode assembly formed by winding up a laminate to which the positive electrode of FIG. 15 is applied. FIG. [Figure 17] 17 is a perspective view showing a state in which a negative electrode uncoated portion extending from an axial end of the electrode assembly of FIG. 14 or FIG. 16 is bent radially inward. FIG. [Figure 18] FIG. 18 is a perspective view showing a state in which current collector plates are welded to the negative electrode uncoated portion and the positive electrode uncoated portion of FIG. 17. [Figure 19] FIG. 20 is a perspective view of a battery cell manufactured by housing the electrode assembly of the embodiment of FIG. 18 in a battery can. [Figure 20] FIG. 20 is a cross-sectional view of the battery cell of FIG. 19. [Figure 21] 18 is a perspective view showing a state in which a current collector plate is welded to the positive electrode uncoated portion of FIG. 17. FIG. [Figure 22] 22 is a perspective view of a battery cell manufactured by housing the electrode assembly of the embodiment of FIG. 21 in a battery can. FIG. [Figure 23] 10 is a side cross-sectional view of an electrode assembly in which an electrode tab is separately connected to a positive electrode; [Figure 24] 24 is a perspective view of a battery cell manufactured to accommodate the electrode assembly of the embodiment of FIG. 23. [Figure 25] 20 is a diagram showing a battery pack manufactured using the battery cell of FIG. 19. [Figure 26] 26 is a diagram showing an electric vehicle equipped with the battery pack of FIG. 25. DETAILED DESCRIPTION OF THE INVENTION

[0066] The above-mentioned objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily implement the technical concept of the present invention. In describing the present invention, if a detailed description of known technologies relating to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0067] Although terms such as "first" and "second" are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0068] Unless otherwise specified in the entire specification, each element may be singular or plural.

[0069] Hereinafter, when an arbitrary structure is arranged "on top (or bottom)" of a component or "above (or below)" a component, it means that the arbitrary structure is not only arranged in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure arranged above (or below) the component.

[0070] Furthermore, 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 other components may be "intervening" between the components, or that each component may be "coupled," "coupled," or "connected" via other components.

[0071] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms such as "comprise" or "include" in this application should not be interpreted as including all of the multiple components or multiple steps described in the specification, but should be interpreted as meaning that some of the components or some of the steps may not be included, or may include additional components or steps.

[0072] Throughout the specification, unless otherwise specified, "A and / or B" means A, B or A and B, and "C to D" means C or more and D or less.

[0073] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0074] In describing the embodiments, the axial direction (Y) refers to the direction in which the axis forming the winding center of the jelly roll-type electrode assembly 1 extends, the radial direction (Z) refers to the direction toward (centripetal) or away (centrifugal) from the axis, and the circumferential direction (X) refers to the direction surrounding the axis. The axial direction (Y) of the electrode assembly 1 corresponds to the width direction (Y) of the electrodes and separator that constitute the laminate before winding, the circumferential direction (X) of the electrode assembly 1 corresponds to the longitudinal direction (X) of the electrodes and separator that constitute the laminate before winding, and the radial direction (Z) of the electrode assembly 1 can correspond to the normal direction (Z) of the sheet-like electrodes and separator that constitute the laminate before winding.

[0075] A cylindrical secondary battery is manufactured by incorporating an electrode assembly 1 wound up in a jelly roll shape inside a cylindrical battery can.

[0076] The electrode assembly 1 accommodated in a cylindrical battery can is formed by sequentially stacking a sheet-like first electrode 2, a first separator 3, a second electrode 4, and a second separator 3 to form a laminate, and then winding the laminate along the longitudinal direction (X) of the sheet. As a result, the jelly roll-type electrode assembly 1 essentially has a shape similar to a thick circular pipe with an open winding shaft. That is, the longitudinal direction of the roll sheet corresponds to the circumferential direction of the cylindrical electrode assembly 1, and the width direction of the roll sheet corresponds to the axial direction of the electrode assembly 1. The normal direction to the surface of the roll sheet corresponds to the radial direction of the electrode assembly 1.

[0077] The first electrode 2 may be a positive electrode, and the second electrode 4 may be a negative electrode. The first separator 3 and the second separator 4 may be made of the same material, but are referred to as the first and second separators 3 to distinguish them according to their stacking positions.

[0078] The first electrode 2 and the second electrode 4 may be rectangular metal foils having a predetermined width in the width direction (Y) and extending long in the length direction (X). For example, the first electrode 2 may be aluminum foil, and the second electrode 4 may be copper foil.

[0079] A first active material 23 is applied to one or both surfaces of the first electrode 2 to form a first electrode coating portion 22. Similarly, a second active material 46 is applied to one or both surfaces of the second electrode 4 to form a second electrode coating portion 42. The other end portion in the width direction (Y) forms a second electrode uncoated portion 41 where no active material is applied.

[0080] In one embodiment, an active material is applied to both surfaces of the first electrode 2 to form a first electrode coated portion 22. One end portion in the width direction (Y) forms a first electrode uncoated portion 21 where no active material is applied.

[0081] As a result, the first electrode uncoated portion 21 is exposed at one axial end of the electrode assembly 1 as shown in the figure, and the second electrode uncoated portion 41 is exposed at the other axial end of the electrode assembly 1 as shown in the figure.

[0082] Any active material known in the art can be used as the positive electrode active material coated on the positive electrode plate (the sheet constituting the first electrode) and the negative electrode active material coated on the negative electrode plate (the sheet constituting the second electrode).

[0083] The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2x Lithium manganese oxides (LiMnO2), such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides, such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x O2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x=0.01 to 0.3); 2-x M x Lithium manganese composite oxides expressed as LiMnO2 (where M=Co, Ni, Fe, Cr, Zn, or Ta, and x=0.01 to 0.1) or Li2Mn3MO8 (where M=Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the lithium in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3; or composite oxides formed by a combination of these, which contain a lithium intercalation material as the main component, include, but are not limited to, the above-mentioned types.

[0084] The positive electrode plate has a thickness of, for example, 3 to 500 μm. There are no particular limitations on the positive electrode plate, as long as it does not cause chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, plastic carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like can be used. The electrode plate can have fine irregularities on its surface to increase the adhesive strength of the positive electrode active material, and can be in various forms, such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0085] A conductive material can be further mixed with the positive electrode active material particles. The conductive material is added, for example, in an amount of 1 to 50 wt % based on the total weight of the mixture containing the positive electrode active material. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0086] The negative electrode sheet is prepared by coating negative electrode active material particles on a negative electrode current collector and drying the coated negative electrode active material particles. If necessary, the negative electrode sheet may further contain components such as the conductive material, binder, and solvent.

[0087] The negative electrode plate has a thickness of, for example, 3 to 500 μm. These negative electrode plates are not particularly limited as long as they do not cause chemical changes in the battery and have conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, plastic carbon, those with a surface treatment of carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used. Also, similar to the positive electrode plate, fine irregularities can be formed on the surface to strengthen the binding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven bodies, etc.

[0088] The negative electrode active material is, for example, carbon such as graphitizable carbon, graphite-based carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0089] The binder polymer usable in the electrode is a component that aids in binding between the electrode active material particles and the conductive material, etc., and between the electrode current collector, and is added in an amount of, for example, 1 to 50 wt % based on the total weight of the mixture including the electrode active material. Examples of these binder polymers include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. The binder polymer may be any one selected from the group consisting of cellulose acetate, cellulose acetate ester, cellulose acetate copolymer ...

[0090] Non-limiting examples of solvents used in the manufacture of the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. These solvents provide an appropriate level of viscosity so that a slurry coating layer can be formed at a desired level on the surface of the electrode current collector.

[0091] The negative electrode comprises a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, the negative electrode active material layer comprising a lower layer region in contact with the current collector and an upper layer region in contact with the lower layer region and extending to the surface of the negative electrode active material layer, and the lower layer region and the upper layer region each independently contain at least one of graphite and a silicon-based compound as the negative electrode active material.

[0092] The lower layer region may contain natural graphite as the negative electrode active material, and the upper layer region may contain artificial graphite as the negative electrode active material.

[0093] The lower layer region and the upper layer region may each independently further include a silicon-based compound as a negative electrode active material.

[0094] The silicon-based compound is SiO x (0≦x≦2) and SiC.

[0095] According to an embodiment of the present invention, the negative electrode may be manufactured by coating a lower layer slurry containing a lower layer negative electrode active material on a current collector and drying the slurry to form a lower layer region, and then coating an upper layer slurry containing an upper layer negative electrode active material on the lower layer region and drying the slurry to form an upper layer region.

[0096] According to one embodiment of the present invention, the negative electrode may be prepared by preparing a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material; coating one surface of a negative electrode plate with the lower layer slurry, and simultaneously or after a predetermined time, coating the upper layer slurry on the lower layer slurry; and The coated lower layer slurry and upper layer slurry are simultaneously dried to form an active material layer.

[0097] In the latter case, a mixed region (intermixing) in which different types of active materials are mixed with each other may exist at the interface between the lower and upper layers of the negative electrode. This is because, when an active material layer is formed by simultaneously or successively coating a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material onto a current collector and then drying them simultaneously, a predetermined mixed region is generated at the interface where the lower layer slurry and the upper layer slurry contact each other before drying, and then, as the slurry dries, this mixed region is formed into a layer of the mixed region.

[0098] In the negative electrode active material layer according to an embodiment of the present invention, the weight ratio (or the ratio of the load amount per unit area) of the upper layer region to the lower layer region may be 20:80 to 50:50, specifically 25:75 to 50:50.

[0099] The thicknesses of the lower and upper layer regions of the anode active material layer of the present invention may not be completely equal to the thicknesses of the coated lower layer slurry and the coated upper layer slurry, but the thickness ratio of the lower and upper layer regions of the anode active material layer of the present invention finally obtained after the drying or selective rolling process may be equal to the thickness ratio of the coated lower layer slurry and the coated upper layer slurry.

[0100] The first slurry is coated, and the second slurry is coated on the first slurry simultaneously or after a predetermined time interval. According to one embodiment of the present invention, the predetermined time difference may be 0.6 seconds or less, or 0.02 to 0.6 seconds, or 0.02 to 0.06 seconds, or 0.02 to 0.03 seconds. Since the time difference between the coating of the first and second slurries is due to the coating equipment, it is more preferable to coat the first and second slurries simultaneously. The method of coating the second slurry on the first slurry can use an apparatus such as a double slot die.

[0101] The step of forming the active material layer may further include a step of rolling the active material layer after the drying step, wherein the rolling may be performed by a method commonly used in the art, such as roll pressing, at a pressure of 1 to 20 MPa and a temperature of 15 to 30°C.

[0102] The step of simultaneously drying the coated lower layer slurry and upper layer slurry to form an active material layer may be carried out by a method commonly used in the art using a combination of a hot air dryer and an infrared dryer.

[0103] The weight % of the first binder polymer in the solid content of the lower layer slurry may be the same as or greater than the weight % of the second binder polymer in the solid content of the upper layer slurry. According to one embodiment of the present invention, the weight % of the first binder polymer in the solid content of the lower layer slurry may be 1.0 to 4.2 times, 1.5 to 3.6 times, or 1.5 to 3 times greater than the weight % of the second binder polymer in the solid content of the upper layer slurry.

[0104] In this case, when the weight percentage of the first binder in the coated lower layer slurry and the weight percentage of the second binder in the coated upper layer slurry satisfy these ranges, the binder in the lower layer region is not too small, so detachment of the electrode layer does not occur, and the binder in the upper layer region is not too large, so the resistance of the upper layer of the electrode is reduced, which is advantageous for fast charging performance.

[0105] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 2 to 30 weight percent, or 5 to 20 weight percent, or 5 to 20 weight percent, and the weight percentage of the second binder polymer in the solid content of the upper layer slurry may be 0.5 to 20 weight percent, or 1 to 15 weight percent, or 1 to 10 weight percent, or 2 to 5 weight percent.

[0106] The total proportion (wt %) of the first binder polymer and the second binder polymer in the total solid content of the lower layer slurry and the upper layer slurry may be 2 to 20 wt %, or 5 to 15 wt %.

[0107] The first electrode 2 and the second electrode 4 may be stacked with a separator 3 interposed therebetween. Another separator 3 may be further stacked under the second electrode 4. When the first electrode 2 and the second electrode 4 are stacked, the first electrode coating portion 22 and the second electrode coating portion 42 may be stacked so as to overlap each other. The separator 3 may be disposed between the first electrode coating portion 22 and the second electrode coating portion 42 so that they do not come into direct contact with each other.

[0108] The boundary between first electrode uncoated portion 21 and first electrode coating portion 22 may be located further inward in the width direction than separator 3 on one width side, and first electrode uncoated portion 21 may extend further toward one width side than separator 3. The boundary between second electrode uncoated portion 41 and second electrode coating portion 42 may be located further inward in the width direction than separator 3 on the other width side, and second electrode uncoated portion 41 may extend further toward the other width side than separator 3.

[0109] The separator includes a porous polymer substrate and porous coating layers disposed on both sides of the porous polymer substrate, the coating layers including inorganic particles and a binder polymer.

[0110] The porous polymer substrate may be a polyolefin-based porous substrate.

[0111] The polyolefin porous substrate may be in the form of a film or non-woven web. The porous structure facilitates smooth movement of the electrolyte between the positive and negative electrodes, improves the electrolyte impregnation of the substrate itself, and ensures excellent ionic conductivity. This prevents an increase in the internal resistance of the electrochemical device, thereby preventing a decrease in the performance of the electrochemical device.

[0112] The polyolefin porous substrate used in the present invention can be any planar porous substrate commonly used in electrochemical devices, and its material and shape can be selected from a variety of options depending on the intended purpose.

[0113] The polyolefin porous substrate may be, but is not limited to, a film or non-woven web formed from high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a mixture of two or more of these.

[0114] The polyolefin porous substrate may have a thickness of 8 to 30 μm, but this is merely an example, and a thickness outside this range may be adopted in consideration of mechanical properties and high-rate charge / discharge characteristics of the battery.

[0115] The nonwoven fabric sheet according to the present invention may be made of polyethylene (PE), polypropylene (PP), or a mixture of two or more of these. For example, the nonwoven fabric sheet may be manufactured by fiber radiating. For example, the nonwoven fabric sheet may be manufactured by melt-blown, in which fibers of the material are radiated at or above their melting point, and then blended and radiated.

[0116] The nonwoven fabric sheet may have an elongation ratio of 200 to 400%, more preferably 300 to 400%. If the elongation ratio is less than 200%, the probability of contact between electrodes increases when a nail penetrates, while if the elongation ratio is greater than 400%, the area around the nail penetration point also elongates, thinning the separator and reducing barrier properties.

[0117] The nonwoven fabric sheet has a plurality of pores with an average diameter of 0.1 to 10 μm formed therein. If the pore size is smaller than 0.1 μm, lithium ions and / or the electrolyte cannot move smoothly, and if the pore size is larger than 10 μm, the effect of the present invention, which is to prevent contact between the positive electrode and the negative electrode by stretching the nonwoven fabric sheet when a nail is penetrated, is difficult to achieve.

[0118] The nonwoven fabric sheet may have a porosity of 40 to 70%. If the porosity is less than 40%, the lithium ions and / or electrolyte solution cannot move smoothly, and if the porosity is greater than 70%, the effect of the present invention, which aims to prevent contact between the positive and negative electrodes by stretching the nonwoven fabric sheet when a nail is penetrated, is difficult to achieve. The nonwoven fabric sheet manufactured in this manner may have an air permeability of 1 to 20 seconds / 100 mL.

[0119] Furthermore, the nonwoven fabric sheet may have a thickness of 10 to 20 μm, but this is merely an example and is not intended to be limiting. Depending on the permeability of the nonwoven fabric sheet, a nonwoven fabric sheet with a thickness outside the above range may also be used.

[0120] The nonwoven fabric sheet can be bonded to the separator components placed underneath the nonwoven fabric sheet by lamination, which can be performed at a temperature ranging from 100 to 150°C. If the lamination is performed at a temperature lower than 100°C, the lamination effect is lost, and if the lamination is performed at a temperature higher than 150°C, part of the nonwoven fabric will melt.

[0121] The separation membrane according to one embodiment of the present invention, which is laminated under the above conditions, has improved resistance to nail penetration when compared to separation membranes made of conventional nonwoven fabric sheets and when compared to separation membranes in which a layer containing inorganic particles is formed on at least one surface of a film or nonwoven fabric sheet.

[0122] The inorganic particles in the porous coating layer are bound to each other by the binder polymer while being charged and in contact with each other, thereby forming interstitial volumes between the inorganic particles, which can become empty spaces to form pores.

[0123] The inorganic particles used to form the porous coating layer are inorganic particles, i.e., particles within the operating voltage range of the electrochemical device (e.g., Li / Li + Inorganic particles that do not undergo oxidation and / or reduction reactions at a voltage (0 to 5 V relative to the reference voltage) can be further added. In particular, when inorganic particles with ion transfer ability are used, the ionic conductivity in the electrochemical device can be increased, thereby improving performance. Furthermore, when inorganic particles with a high dielectric constant are used as the inorganic particles, they can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution.

[0124] For the reasons mentioned above, the inorganic particles preferably include high-dielectric-constant inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having lithium ion transfer ability, or a mixture thereof.

[0125] Non-limiting examples of inorganic particles with a dielectric constant of 5 or greater include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, or mixtures thereof.

[0126] In particular, the aforementioned BaTiO3, Pb(Zr,Ti)O3 (PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg 1 / 3 Nb 2 / 3 Inorganic particles such as )O3-PbTiO3 (PMN-PT) and hafnia (HfO2) not only exhibit high dielectric constant characteristics with a dielectric constant of 100 or more, but also possess piezoelectricity, which generates electric charges and creates a potential difference between the two surfaces when stretched or compressed under a certain pressure. This prevents internal short circuits between the electrodes due to external impact and improves the stability of electrochemical devices. Furthermore, when the above-mentioned high dielectric constant inorganic particles are mixed with inorganic particles having lithium ion transport ability, these improved effects can be doubled.

[0127] Inorganic particles having lithium ion transfer ability refer to inorganic particles that contain lithium elements but do not store lithium and have the function of moving lithium ions. Inorganic particles having lithium ion transfer ability can transfer and move lithium ions due to a kind of defect existing inside the particle structure, so the lithium ion conductivity in the battery is improved, and thereby the battery performance can be enhanced. In non-limiting examples of the inorganic particles having lithium ion transfer ability, there are lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, x O y 0 < z < 3), (LiAlTiP) x O y -based glasses such as 14Li2O - 9Al2O3 - 38TiO2 - 39P2O5 (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La<00000 y TiO3, 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate such as Li 3.25 Ge 0.25 P 0.75 S4 (Li x Ge y P z S w , 0 < x < 4, 0 < y < x N y 1, 0 < z < 1, 0 < w < 5), lithium nitride such as Li3N (Li<00 x N y , 0 < x < 4, 0 < y < x Si y S z -based glasses such as Li3PO4 - Li2S - SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 - based glasses such as LiI - Li2S - P2S5 (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7), or mixtures thereof, etc.

[0128] Although there is no limitation on the size of the inorganic particles in the porous coating layer, it is preferably 0.001 to 10 μm to form a coating layer of uniform thickness and appropriate porosity. If it is less than 0.001 μm, the dispersibility of the inorganic particles may be reduced, and if it exceeds 10 μm, the thickness of the porous coating layer may increase, which may reduce mechanical properties. In addition, the pore size may be too large, increasing the probability of internal short circuits occurring during battery charge and discharge.

[0129] Binder polymers that form the porous coating layer include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. The binder polymer may be any one selected from the group consisting of cellulose acetate, cellulose acetate ester, cellulose acetate copolymer ...

[0130] The composition ratio of inorganic particles to binder polymer used in the porous coating layer is preferably, for example, in the range of 50:50 to 99:1, more preferably 70:30 to 95:5. If the ratio of inorganic particles to binder polymer is less than 50:50, the binder polymer content will be too high, which may result in a decrease in the improvement of the thermal stability of the separator. Furthermore, the pore size and porosity will decrease due to a decrease in the void space formed between the inorganic particles, ultimately resulting in a decrease in battery performance. If the inorganic particle content exceeds 99 parts by weight, the binder polymer content will be too low, which may weaken the peel resistance of the porous coating layer. The thickness of the porous coating layer is not particularly limited, but is preferably in the range of 0.01 to 20 μm. The pore size and porosity are also not particularly limited, but the pore size is preferably in the range of 0.001 to 10 μm, and the porosity is preferably in the range of 10 to 90%. The pore size and porosity depend mainly on the size of the inorganic particles. For example, when inorganic particles with a particle size of 1 μm or less are used, the pores formed will also be approximately 1 μm or less. These pore structures are filled with the electrolyte solution that is subsequently injected, and the filled electrolyte solution plays a role in transferring ions. If the pore size and porosity are less than 0.001 μm and 10%, respectively, the material may function as a resistance layer. However, if the pore size and porosity are greater than 10 μm and 90%, respectively, the mechanical properties may be degraded.

[0131] The porous coating layer can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to obtain a slurry for forming the porous coating layer, and then coating and drying the slurry on at least one surface of a substrate. The dispersion medium preferably has a solubility index similar to that of the binder polymer to be used and a low boiling point. This allows for uniform mixing and easy subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0132] It is preferable to add inorganic particles to a dispersion in which the binder polymer is dispersed in a dispersion medium, and then crush the inorganic particles. In this case, the crushing time is appropriately 1 to 20 hours, and the particle size of the crushed inorganic particles is preferably 0.001 to 10 μm, as described above. As a crushing method, a conventional method can be used, and a ball mill method is particularly preferable.

[0133] The binder polymer dispersion liquid containing the dispersed inorganic particles is then coated onto at least one surface of a porous polymer substrate under a humidity condition of 10 to 80% and dried. The dispersion liquid can be coated onto the porous polymer substrate using a conventional coating method known in the art, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0134] The porous coating layer may further include other additives such as a conductive agent in addition to the inorganic particles and binder polymer described above.

[0135] The final separator according to the present invention may have a thickness of 1 to 100 μm or 5 to 50 μm. If the thickness is less than 1 μm, the separator may not function properly and mechanical properties may deteriorate, while if the thickness is more than 100 μm, battery properties may deteriorate during high-rate charge / discharge. The separator may also have a porosity of 40 to 60% and an air permeability of 150 to 300 seconds / 100 mL.

[0136] According to an embodiment of the present invention, the porous polymer substrate may be polyethylene or polypropylene-based, and the inorganic particles in the porous coating layer may be aluminum oxide or silicon oxide-based coating materials.

[0137] When using a separator according to an embodiment of the present invention, porous coating layers are provided on both sides of a porous polymer substrate, which improves electrolyte impregnation performance and allows for the formation of a uniform solid electrolyte interfacial layer. This ensures superior air permeability compared to conventional single-sided inorganic-coated separators. For example, it may be within 120 s / 100 cc. Furthermore, even though inorganic porous coating layers are provided on both sides, it is possible to achieve the same thickness as conventional single-sided inorganic-coated separators. For example, it may be within 15.0 μm.

[0138] Furthermore, when a separator according to an embodiment of the present invention is used, the separator's stability is improved and heat resistance and compression resistance are ensured. Specifically, the separator can have heat resistance with a thermal shrinkage of 5% or less at 180°C, and a puncture strength of 550 gf or more. This prevents damage or puncture of the separator at the step when core deformation occurs during cycling of a battery using such a separator.

[0139] The thickness of the first electrode 2 may be greater than the thickness of the second electrode 4. The rigidity of the material of the first electrode 2 may be greater than the rigidity of the material of the second electrode 4. The widthwise extending length of the second electrode uncoated portion 41 may be greater than the widthwise extending length of the first electrode uncoated portion 21. In this way, the second electrode uncoated portion 41 may be made of a material that is relatively less rigid than the first electrode uncoated portion 21, and may have a greater extending length and a shorter thickness. As a result, when the uncoated portion is compressed in the axial direction, the second electrode uncoated portion 41 is more likely to buckle than the first electrode uncoated portion 21.

[0140] The area of ​​the first electrode 2 is smaller than the area of ​​the second electrode 4. That is, the width and length of the first electrode 2 are slightly smaller than the width and length of the second electrode 4. As a result, as shown in FIG. 7, in a state where the first electrode 2, first separator 3, second electrode 4, and second separator 3 are stacked, the second electrode 4 extends further outward than the first electrode 2 in the longitudinal direction.

[0141] The width of the first electrode coating portion 22 is also shorter than the width of the second electrode coating portion 42. As a result, the second electrode coating portion 42 extends further outward in the width to axial directions than the first electrode coating portion 22. Conversely, this means that the distance that the other axial end of the first electrode 2 is axially inward from the other axial end of the separator 3 is longer than the distance that one axial end of the second electrode 4 is axially inward from one axial end of the separator 3. In other words, because the other axial end of the first electrode 2 is hidden deeper inside the separator 3 than one axial end of the second electrode 4, it can be inferred at a glance that the possibility of a short circuit between the first electrode 2 and the second electrode 4 is higher at one axial end of the electrode assembly 1 where the first electrode uncoated portion 21 extends.

[0142] However, as mentioned above, it is important to note that the second electrode uncoated portion 41 is more susceptible to buckling than the first electrode uncoated portion 21, and therefore there is a high possibility that the second electrode uncoated portion 41 will buckle, invade the separation membrane 3, and come into contact with the other axial end of the first electrode 2, causing a short circuit.

[0143] The first electrode uncoated region 21 and the second electrode uncoated region 41 exposed on both axial sides of the electrode assembly 1 can be folded radially inward, i.e., in a centripetal direction, as shown in the figure. The folded uncoated regions can provide a substantially flat surface in the axial direction. The first electrode current collector 5 and the second electrode current collector 6 can be welded to the folded and flattened uncoated regions on both axial sides, respectively, for electrical connection.

[0144] In the embodiment, the description will focus on the welding of the second electrode current collector 6 to the bent surface of the second electrode uncoated portion 41. During the process of welding the second electrode current collector 6 to the welding portion of the second electrode uncoated portion 41, the second electrode current collector 6 maintains a state of being in close contact with the second electrode uncoated portion 41. During this process, the second electrode current collector 6 presses the second electrode uncoated portion 41 in the axial direction.

[0145] At this time, a fairly large pressure is applied to maintain the tight contact state, which may cause the base end of the second electrode uncoated portion 41 to buckle as shown in Figure 4. For this reason, in this embodiment of the present invention, an insulating coating layer 45 is formed near the base end of the second electrode uncoated portion 41, where buckling is most likely to occur.

[0146] The insulating coating layer 45 includes a polymer resin and may include an inorganic filler such as Al2O3.

[0147] The insulating coating layer 45 reinforces the rigidity of the vicinity of the base end of the second electrode uncoated portion 41. As a result, when the second electrode uncoated portion 41 receives an axial force from the second electrode current collector plate 6, the bottom 301F of the battery can 301C, or the cap 307 for welding the second electrode uncoated portion 41, the base end of the second electrode uncoated portion 41 does not buckle.

[0148] When the base end of the second electrode uncoated portion 41 is reinforced with an insulating coating layer 45, even if the base end of the second electrode uncoated portion 41 buckles, the second electrode uncoated portion 41 and the first electrode 2 do not come into direct contact with each other but come into contact with each other via the insulating coating layer 45, thereby preventing a short circuit from occurring between the first electrode 2 and the second electrode 4.

[0149] The insulating coating layer 45 provides bending resistance in the process of bending the second electrode uncoated portion 41 in the radial direction. As a result, when bending the second electrode uncoated portion 41 in the radial direction, the section coated with the insulating coating layer 45 is hardly deformed, and deformation occurs mainly in the section not coated with the insulating coating layer 45.

[0150] The insulating coating layer 45 covers a predetermined section from the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 toward the end of the second electrode uncoated portion 41. The insulating coating layer 45 starts from a position inside the axial end of the separator 3 and extends further outward in the axial direction than the separator 3.

[0151] When the insulating coating layer 45 covers the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41, it also covers the small section 43 at the end of the second electrode coating portion 42. The portion where the greatest deformation occurs due to buckling may be the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41. Because the insulating coating layer 45 covers the small section 43 at the end of the second electrode coating portion 42 at these boundary portions, the buckling resistance of the boundary between the second electrode coating portion 42 and the second electrode uncoated portion 41 is greatly increased.

[0152] The insulating coating layer 45 may have a constant thickness or may have a thickness that varies in the axial direction. Figure 10 shows a structure in which the thickness of the insulating coating layer 45 gradually increases in a glide section (a section where the thickness decreases) formed at the end of the negative electrode active material. The thickness of the insulating coating layer 45 in the section covering the second electrode uncoated portion 41 is constant.

[0153] On the other hand, FIG. 11 shows a configuration in which the thickness of the insulating coating layer 45 is constant not only in the section covering the second electrode uncoated portion 41 but also in the gliding section.

[0154] The thickness of the insulating coating layer 45 may be thinner than the thickness of the negative electrode active material layer. As a result, as shown in the figure, the second electrode coating portion 42 may be in close contact with the separator 3 in the radial direction, but the insulating coating layer 45 may be spaced apart from the separator 3 to some extent, or may be in contact with the separator 3 but not in close contact.

[0155] As a result, even if an external force is applied to second electrode uncoated portion 41 during the process of bending second electrode uncoated portion 41 and during the process of welding second electrode current collector plate 6 to second electrode uncoated portion 41, the amount of deformation can be suppressed, and the deformation of the base end of second electrode uncoated portion 41 does not immediately affect separator 3. In other words, second electrode uncoated portion 41 has a section, the distance between insulating coating layer 45 and separator 3, that does not affect separator 3 but is allowed to deform.

[0156] Furthermore, when the insulating coating layer 45 is spaced apart from the separator 3, heat generated during the welding of the second electrode uncoated portion 41 to the second electrode current collector plate 6, the bottom 301F of the battery can 301C, or the cap 307 is prevented from being directly conducted to the separator 3 via the insulating coating layer 45, thereby protecting the separator 3 from the welding heat. Furthermore, the insulating coating layer 45 can further reduce the axial protrusion height of the separator 3, thereby further increasing the distance from the position where the welding heat is generated to the axial end of the separator 3, thereby further increasing the effect of protecting the separator 3 from the welding heat.

[0157] Because the electrode assembly 1 is wound into a cylindrical shape, the insulating coating region of the second electrode uncoated portion 41 coated with the insulating coating layer 45 also has a cylindrical curved surface. The cylindrical curved surface itself has bending resistance. According to the embodiment, the insulating coating region has a thicker cylindrical curved surface, so when the region above the cylindrical curved surface is bent in the radial direction, the insulating coating region provides higher bending resistance. As a result, bending is induced in the non-insulating coated portion of the second electrode uncoated portion 41.

[0158] In this case, since the insulating coating region provides a higher bending resistance, the thickness of the insulating coating layer 45 is thinner than the thickness of the negative electrode active material layer, and the surface of the insulating coating layer 45 is spaced apart from the separator 3 in the radial direction, so that the bending resistance can be sufficiently exerted even if it is not supported by the separator 3.

[0159] The tip end of the insulating coating layer 45 is coated to maintain a slight gap (G) from the bending portion (F) of the second electrode uncoated portion 41. This has the effect of inducing the second electrode uncoated portion 41 to bend at the bending portion (F). In addition, because the second electrode uncoated portion 41 deforms with a slight gap (G) from the insulating coating layer 45, it is possible to prevent the insulating coating layer 45 from being damaged during the uncoated portion bending process.

[0160] In this way, the second electrode uncoated portion 41 having the insulating coating layer 45 can prevent buckling even when pressed axially by the second electrode current collector plate 6, as shown in FIG. 12.

[0161] Meanwhile, the second electrode uncoated portion 41 may be provided with a folding guide structure (N, T) that guides the second electrode uncoated portion 41 to fold at a predetermined axial position. The folding guide structure (N, T) may be, for example, a notch (N) that cuts the second electrode uncoated portion 41 in the axial direction from the tip of the second electrode uncoated portion 41 only for the axial section where the second electrode uncoated portion 41 needs to be folded, and a notched tab (T) structure segmented by the notch (N). These folding guide structures (N, T) more accurately guide the folding position (F) of the second electrode uncoated portion 41 to the lower end of the notched tab (T). Of course, a similar folding guide structure can also be applied to the first electrode uncoated portion 21 (see FIG. 15).

[0162] Referring to FIG. 13, the notched tabs (T) in the uncoated portion may have a shape in which their height gradually increases from the core side (left side in the drawing) to the outer periphery side (right side in the drawing). This allows the notched tabs (T) to lie radially inward during the bending process of the second electrode uncoated portion 41, further increasing the flatness of the notched tabs (T). Furthermore, even if the notched tabs (T) are completely removed on the core side and bent radially inward, the folded notched tabs (T) can be prevented from covering the hollow portion of the electrode assembly 1. Furthermore, removing the notched tab (T) corresponding to the last winding turn on the outer periphery can prevent unexpected deformation of the notched tabs (T) of the outermost turn during handling of the electrode assembly 1.

[0163] The insulating coating layer 45 may be provided in a section from a boundary between the second electrode coating portion 42 and the second electrode non-coating portion 41 to the bending guide structures (N, T).

[0164] The insulating coating layer 45 may cover at least a portion of the section in the axial direction.

[0165] In the embodiment, an insulating coating layer 45 is applied to the base end of the second electrode uncoated portion 41. However, it goes without saying that the insulating coating layer 45 can also be applied to the first electrode uncoated portion 21.

[0166] FIG. 14 shows an electrode assembly 1 in a wound state in which a second electrode 4 in which the height of the notched tabs (T) gradually increases toward the outer periphery and a first electrode 2 in which the height of the first electrode uncoated portion 21 is constant, as shown in FIG.

[0167] FIG. 16 shows an electrode assembly in which a second electrode 4 having a shape in which the height of the notched tabs (T) gradually increases toward the outer periphery as shown in FIG. 13 and a first electrode 2 having a shape in which the height of the notched tabs (T) gradually increases toward the outer periphery as shown in FIG. 15 are wound together.

[0168] If the height of the first electrode uncoated region 21 and / or the second electrode uncoated region 41 gradually decreases toward the center, even if these regions are bent in the centripetal direction, the hollow portion of the core of the electrode assembly 1 can remain open in the axial direction, as shown in Fig. 17. This can serve as a passage for a welding jig or a path for injection and impregnation of the electrolyte.

[0169] The first electrode current collector plate 5 and the second electrode current collector plate 6 are attached and fixed to the surfaces of the overlapped first electrode uncoated portion 21 and second electrode uncoated portion 41, respectively, by a method such as welding, as shown in FIG. 18.

[0170] The insulating coating layer 45 may extend further axially outward than the separation membrane 3. This prevents the second electrode uncoated portion 41 from being electrically short-circuited with the adjacent first electrode 2 via the separation membrane 3, even if buckling occurs at the base end of the second electrode uncoated portion 41.

[0171] The insulating coating layer 45 may not completely cover the bending guide structures (N, T) or the bending position, but may only cover a predetermined gap (G), thereby preventing stress from being transmitted to the insulating coating layer 45 when bending occurs at the bending position, thereby preventing an effect on the buckling resistance of the insulating coating layer 45.

[0172] The gap (G) section, where the insulating coating layer 45 is not formed, has a weaker buckling resistance than the section where the insulating coating layer 45 is formed. Therefore, even if the second electrode uncoated portion 41 buckles due to the pressure of the second electrode current collector plate 6, it can be guided to the gap (G) section. Because the bending position is a considerable distance away from the first electrode 2 in the axial direction, even if buckling occurs in the gap (G) section, the portion in question will not come into contact with the first electrode 2. In other words, the gap (G) section can be located at a sufficient distance from the other axial end of the first electrode 2 that the portion in question will not come into contact with the first electrode 2 even if buckling occurs.

[0173] The insulating coating layer 45 has the effect of further increasing the thickness of the second electrode uncoated portion 41. Therefore, the buckling resistance of the second electrode uncoated portion 41 is further increased in the area covered by the insulating coating layer 45.

[0174] Furthermore, even if the second electrode uncoated portion 41 buckles in an unexpected section of the insulating coating layer 45, that portion is covered with the insulating coating layer 45, so there is no possibility of contact with the first electrode 2 and a short circuit occurring.

[0175] The insulating coating layer 45 can be coated on the uncoated areas of the electrode that are more susceptible to buckling, based on the uncoated area section where buckling may occur. If the uncoated areas including the first electrode uncoated area 21 and the second electrode uncoated area 41 are each bent based on the bending position (F), the section where buckling occurs is from the bending position (F) to the boundary between the uncoated area and the active material coating area. In FIG. 10, this refers to the section from the top of the gap (G) section to the top of the minute section 43. Given the length (L) of this section, the thickness (t) of the electrode foil, and the elastic modulus (E) of the metal, the buckling load per unit length in the circumferential direction of the uncoated area is L 2 It is inversely proportional to the elastic modulus (E) and proportional to the moment of inertia (I). The moment of inertia (I) per unit length is t 3 Therefore, the magnitude of the buckling resistance of the first electrode uncoated portion 21 and the second electrode uncoated portion 41 is proportional to Et 3 / L 2 It can be determined from the value.

[0176] 18 may be housed inside a battery can 301C as shown in Figures 19 and 20. The battery can 301C may be connected to the second electrode collector plate 6 of the electrode assembly 1 to form a negative terminal, and a rivet terminal 301R provided at the center of one end of the battery can 301C may be connected to the first electrode collector plate 5 of the electrode assembly 1 to form a positive terminal. In other words, the electrode assembly 1 may be housed in the battery can 301C to form a cylindrical battery cell 301.

[0177] 20, the peripheral portion of the first electrode current collector 5 is welded to the first electrode uncoated portion 21, and the center portion of the first electrode current collector 5 is welded to the electrode terminal 301R, which may have the polarity of the first electrode. An insulator 308 is interposed between the first electrode current collector 5 and the bottom 301F of the battery can 301C to insulate the battery can 301C from the first electrode.

[0178] The second electrode current collector 6 has an open center, allowing the hollow portion of the winding core of the electrode assembly 1 to be exposed in the axial direction. As shown in the figure, a portion of the second electrode current collector 6 is welded to the second electrode uncoated portion 41 coated with an insulating coating layer 45, and a portion of the second electrode current collector 6 is crimped or welded to the battery can 301C.

[0179] The open end of the battery can 301C is finished with a cap 307 via a gasket 307. Figure 20 shows a state in which the cap 307, which has a fragile portion 309 formed therein for venting, is crimped and fixed to the crimping portion (C) of the battery can 301C via the gasket 307. A portion of the second electrode uncoated portion 41 is engaged with the crimping portion (C), allowing current to flow between the second electrode and the battery can 301C.

[0180] 20, the embodiment illustrates a structure in which the second electrode current collector 6 is engaged with the crimping portion (C). However, as long as the second electrode can be electrically connected to the battery can 301C, the second electrode current collector 6 may also be interposed between the beading portion (B) and the electrode assembly 1. These may also be electrically connected by crimping and / or welding.

[0181] 21 discloses an electrode assembly 1 in which the second electrode current collector 6 is not connected to the second electrode uncoated portion 41, and only the first electrode current collector 5 is connected to the first electrode uncoated portion 21. In this structure, for example, as shown in FIG. 22, the bent portion of the second electrode uncoated portion 41 coated with the insulating coating layer 45 can be directly welded to the cap 307 of the battery can 301C.

[0182] 22, the second electrode uncoated portion 41 is directly welded to the cap 307. The cap 307 has the second electrode polarity, and the battery can 301C also has the second electrode polarity, so the cap 307 and the battery can 301C can be fixed by welding, soldering, etc. A weak portion 309 is provided in the center of the cap 307 to implement a vent function, and the weak portion 309 can also function as a liquid inlet.

[0183] According to this embodiment, in order to weld the cap 307 to the second electrode uncoated portion 41, the cap 307 presses the second electrode uncoated portion 41 in the axial direction. At this time, the insulating coating layer 45 has sufficient rigidity to resist such a pressing force and therefore does not buckle. In addition, the rigidity of the insulating coating layer 45 can reduce the axial protrusion length of the separator 3, so that heat generated when welding the cap 307 to the second electrode uncoated portion 41 can be prevented from affecting the separator 3.

[0184] 23 and 24 disclose structures in which the second electrode uncoated portion 41 is bent and then directly connected to the bottom of the battery can 301C without the second electrode current collector 6, and the first electrode 2 is electrically connected to the electrode terminal 301R of the cap 307 via the electrode tab 7. In these structures, as shown in the figures, the bent portion of the second electrode uncoated portion 41 coated with the insulating coating layer 45 can be directly welded to the bottom 301F of the battery can 301C.

[0185] As in the embodiment, the second electrode 4, which has a relatively high internal resistance, significantly reduces its internal resistance by utilizing the second electrode uncoated portion 41, which has many current paths, and the first electrode 2 reduces its internal resistance by utilizing two or more electrode tabs 7, while also applying a vent structure 309. Although not shown, it is of course possible to apply a thermal runaway prevention structure (CID; Current Interrupt Device) to the cap 307.

[0186] When the vent structure or CID structure is applied to the cap 307, the assembly method is facilitated by using a structure similar to an electrode tab. However, if the first electrode uncoated portion 21 and the first electrode current collector plate 5 are applied to the first electrode 2 in such a structure as in the above-described embodiment, they take up a considerable amount of volume in the axial direction, which is detrimental to ensuring electrical capacity. For this reason, in this embodiment, the electrode tab 7 is used to connect the first electrode 2 to the electrode terminal 301R, thereby further ensuring electrical capacity.

[0187] Furthermore, the bent first electrode uncoated portion 21 and first electrode current collector plate 5 may hinder or prevent the withstand voltage of the battery can 301C from affecting the vent structure and CID structure, which may be somewhat detrimental to the implementation of these functions. On the other hand, by using two or more electrode tabs 7 as in the embodiment, the internal resistance can be reduced as needed without affecting the vent function and CID function.

[0188] FIG. 25 shows a battery pack 300 in which these battery cells 301 are housed in a housing 302 and connected in series and / or parallel using bus bars or the like, thereby being able to supply an appropriate voltage and current.

[0189] 26 shows an automobile (V) equipped with the battery pack 300. In this way, the battery cell 301 to which the insulating coating layer 45 of the present invention is applied can be used for vehicles. The battery cell 301 can also be used in various other fields.

[0190] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. All modifications and variations within the meaning and scope of the following claims, as well as equivalent concepts, should be construed as being included within the scope of the present invention.

[0191] Although the present invention has been described above with reference to illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the technical scope of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while describing the embodiments of the present invention, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0192] 1 Electrode assembly 2. First electrode (positive electrode) 20 First electrode foil 21 1st electrode plain area 22 First electrode coating section 23 First active material 3 Separation membrane 4 Second electrode (negative electrode) 40 Second electrode foil 41 2nd electrode plain area F bending position G Gap N Notch T-notch tab 42 Second electrode coating section 43 Minor Sections 45 insulating coating layer 46 Second active material 5 First electrode current collector plate 6 Second electrode current collector plate 7 Electrode tabs 300 Battery Pack 301 Battery Cell 301C Battery Can 301R Electrode terminal (rivet terminal) 301F bottom 302 Housing 306 Gasket 307 Cap 308 Insulator 309 Weakened Part B Beading section C Crimping part V vehicle Y-axis direction (width direction) X Circumferential direction (longitudinal direction) Z Radial direction (normal direction)

Claims

1. An electrode assembly (1) in a state in which a first electrode (2) and a second electrode (4) are stacked with a separation membrane (3) interposed therebetween, and the first electrode (2), the second electrode (4), and the separation membrane (3) are wound up, The first electrode (2) has a first electrode coating portion (22) which is a region where an active material is applied to the surface of the first electrode (2), The second electrode (4) has a second electrode coating portion (42) which is a region where an active material is applied to the surface of the second electrode (4), The second electrode (4) is a second electrode non-coating portion (41) which is a region where no active material is applied at one axial end of the second electrode (4); and an insulating coating layer (45) formed by coating a predetermined section from the boundary between the second electrode coating portion (42) and the second electrode non-coating portion (41) toward the end of the second electrode non-coating portion (41) with an insulating material; Furthermore, The insulating coating layer (45) is thinner than the second electrode coating portion (42), The boundary between the second electrode coating portion (42) and the second electrode uncoated portion (41) is located further inward in the axial direction than the axial end of the separation membrane (3), The insulating coating layer (45) extends further axially outward than the axial end of the separation membrane (3), The second electrode non-coating portion (41) is bent in the radial direction of the electrode assembly (1) at a predetermined bending position (F), The bending position (F) is disposed further outward in the axial direction than the end of the separation membrane (3), The insulating coating layer (45) does not cover the second electrode non-coating portion (41) by a predetermined gap (G) in the axial direction from the bending position (F), When the insulating coating layer (45) covers the boundary between the second electrode coating portion (42) and the second electrode non-coating portion (41), it also covers a small section (43) at the end of the second electrode coating portion (42). Electrode assembly (1).

2. An electrode assembly (1) in a state in which a first electrode (2) and a second electrode (4) are stacked with a separation membrane (3) interposed therebetween, and the first electrode (2), the second electrode (4), and the separation membrane (3) are wound up, The first electrode (2) has a first electrode coating portion (22) which is a region where an active material is applied to the surface of the first electrode (2), The second electrode (4) has a second electrode coating portion (42) which is a region where an active material is applied to the surface of the second electrode (4), The second electrode (4) is a second electrode non-coating portion (41) which is a region where no active material is applied at one axial end of the second electrode (4); and an insulating coating layer (45) formed by coating a predetermined section from the boundary between the second electrode coating portion (42) and the second electrode non-coating portion (41) toward the end of the second electrode non-coating portion (41) with an insulating material; Furthermore, The insulating coating layer (45) is thinner than the second electrode coating portion (42), The boundary between the second electrode coating portion (42) and the second electrode uncoated portion (41) is located further inward in the axial direction than the axial end of the separation membrane (3), The insulating coating layer (45) extends further axially outward than the axial end of the separation membrane (3), The second electrode non-coating portion (41) is bent in the radial direction of the electrode assembly (1) at a predetermined bending position (F), The bending position (F) is disposed further outward in the axial direction than the end of the separation membrane (3), The insulating coating layer (45) does not cover the second electrode non-coating portion (41) by a predetermined gap (G) in the axial direction from the bending position (F), The second electrode uncoated portion (41) has a notch (N) formed axially inward from its end, A plurality of the notches (N) are arranged at intervals along the circumferential direction of the second electrode (4), a second electrode uncoated portion disposed between two adjacent notched portions (N) in the circumferential direction defines a notched tab (T); The bending position (F) is located at the base end of the notched tab (T). Electrode assembly (1).

3. An electrode assembly (1) in a state in which a first electrode (2) and a second electrode (4) are stacked with a separation membrane (3) interposed therebetween, and the first electrode (2), the second electrode (4), and the separation membrane (3) are wound up, The first electrode (2) has a first electrode coating portion (22) which is a region where an active material is applied to the surface of the first electrode (2), The second electrode (4) has a second electrode coating portion (42) which is a region where an active material is applied to the surface of the second electrode (4), The second electrode (4) is a second electrode non-coating portion (41) which is a region where no active material is applied at one axial end of the second electrode (4); and an insulating coating layer (45) formed by coating a predetermined section from the boundary between the second electrode coating portion (42) and the second electrode non-coating portion (41) toward the end of the second electrode non-coating portion (41) with an insulating material; Furthermore, The insulating coating layer (45) is thinner than the second electrode coating portion (42), The boundary between the second electrode coating portion (42) and the second electrode uncoated portion (41) is located further inward in the axial direction than the axial end of the separation membrane (3), The insulating coating layer (45) extends further axially outward than the axial end of the separation membrane (3), The second electrode non-coating portion (41) is bent in the radial direction of the electrode assembly (1) at a predetermined bending position (F), The bending position (F) is disposed further outward in the axial direction than the end of the separation membrane (3), The insulating coating layer (45) does not cover the second electrode non-coating portion (41) by a predetermined gap (G) in the axial direction from the bending position (F), The first electrode (2) has a first electrode uncoated portion (21) which is a region where no active material is applied at the other axial end of the first electrode (2), The buckling resistance of the second electrode uncoated portion (41) is lower than the buckling resistance of the first electrode uncoated portion (21). Electrode assembly (1).

4. An electrode assembly (1) in a state in which a first electrode (2) and a second electrode (4) are stacked with a separation membrane (3) interposed therebetween, and the first electrode (2), the second electrode (4), and the separation membrane (3) are wound up, The first electrode (2) has a first electrode coating portion (22) which is a region where an active material is applied to the surface of the first electrode (2), The second electrode (4) has a second electrode coating portion (42) which is a region where an active material is applied to the surface of the second electrode (4), The second electrode (4) is a second electrode non-coating portion (41) which is a region where no active material is applied at one axial end of the second electrode (4); and an insulating coating layer (45) formed by coating a predetermined section from the boundary between the second electrode coating portion (42) and the second electrode non-coating portion (41) toward the end of the second electrode non-coating portion (41) with an insulating material; Furthermore, The insulating coating layer (45) is thinner than the second electrode coating portion (42), The boundary between the second electrode coating portion (42) and the second electrode uncoated portion (41) is located further inward in the axial direction than the axial end of the separation membrane (3), The insulating coating layer (45) extends further axially outward than the axial end of the separation membrane (3), The second electrode non-coating portion (41) is bent in the radial direction of the electrode assembly (1) at a predetermined bending position (F), The bending position (F) is disposed further outward in the axial direction than the end of the separation membrane (3), The insulating coating layer (45) does not cover the second electrode non-coating portion (41) by a predetermined gap (G) in the axial direction from the bending position (F), The first electrode (2) is welded to an uncoated area where no active material is applied, and is provided with an electrode tab (7) protruding from the other axial side of the first electrode (2). Electrode assembly (1).

5. Two or more of the electrode tabs (7) are welded and connected to the plain area. Electrode assembly (1) according to claim 4.

6. The insulating coating layer (45) covers at least a part of the section from the boundary between the second electrode coating portion (42) and the second electrode uncoated portion (41) to the bending position (F) of the second electrode uncoated portion (41). Electrode assembly (1) according to any one of claims 1 to 5.

7. The first electrode (2) is a positive electrode and the second electrode (4) is a negative electrode. Electrode assembly (1) according to any one of claims 1 to 5.

8. The second electrode coating portion (42) is arranged to have a width in the axial direction that is wider than that of the first electrode coating portion (22), whereby both axial end portions of the second electrode coating portion (42) are arranged to extend further outward in the axial direction than both axial end portions of the first electrode coating portion (22). Electrode assembly (1) according to any one of claims 1 to 5.

9. The thickness of the second electrode (4) is thinner than the thickness of the first electrode (2). Electrode assembly (1) according to any one of claims 1 to 5.

10. The first electrode (2) has a first electrode uncoated portion (21) which is a region where no active material is applied at the other axial end of the first electrode (2), The axial length of the second electrode uncoated portion (41) is longer than the axial length of the first electrode uncoated portion (21). Electrode assembly (1) according to any one of claims 1 to 3.

11. The insulating coating layer (45) is coated on a region of the second electrode non-coating portion (41) having a curvature along the circumferential direction. Electrode assembly (1) according to any one of claims 1 to 5.

12. The electrode assembly (1) according to any one of claims 1 to 5, and a battery can (301C) containing the electrode assembly (1), Battery cell.

13. The bent portion (F) of the second electrode non-coating portion (41) is located in an area where the insulating coating layer (45) is not coated. The battery cell of claim 12 .

14. The second electrode uncoated portion (41) is welded to the second electrode current collector plate (6) or directly welded to the bottom (301F) or cap (307) of the battery can (301C). The battery cell of claim 13 .

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