Electrode assembly, battery, battery pack including same, and automobile

Abstract

An electrode assembly according to an embodiment of the present invention has a structure in which a core and an outer circumferential surface are defined by winding sheet-like first and second electrodes and a separator interposed between the first and second electrodes around an axis. The first and second electrodes each include an uncoated portion at a long side end where an active material layer is not coated, and a coated portion where an active material layer is coated in an area other than the uncoated portion. The first electrode includes an insulating layer simultaneously covering at least a portion of the uncoated portion and at least a portion of the coated portion along the winding direction. The uncoated portion of the first electrode is folded in a radial direction of the electrode assembly, and a folding point is spaced apart from an axial end of the insulating layer. At least a portion of the uncoated portion of the first electrode is used as an electrode tab by itself.

Description

[Technical Field]

[0001] The present invention relates to an electrode assembly, a battery, a battery pack including the same, and a vehicle.

[0002] This application claims priority from Korean Patent Application No. 10-2021-0103388 filed on August 5, 2021, Korean Patent Application No. 10-2021-0137200 filed on October 15, 2021, and Korean Patent Application No. 10-2021-0190215 filed on December 28, 2021, and the contents disclosed in the specifications and drawings of those applications are incorporated into this application in their entirety. [Background technology]

[0003] In cylindrical batteries, a jelly-roll type electrode assembly is used in which positive and negative electrode tabs extend vertically along the height direction of the battery housing to maximize current collection efficiency.

[0004] In such a structure, movement such as lateral motion of the positive or negative electrode may occur. In this case, the end of the positive or negative electrode may be located near the end of the separator. Therefore, if movement such as lateral motion of the positive or negative electrode causes the positive or negative electrode to be positioned up to the end of the separator or to protrude beyond the end of the separator, electrical contact between the positive and negative electrodes may occur. Alternatively, if the separator is damaged for some reason, electrical contact between the positive and negative electrodes may occur. As a result, a short circuit may occur within the battery. A short circuit within the battery may cause the battery to overheat or explode. Therefore, an insulating member is required to effectively prevent electrical contact between the positive and negative electrodes.

[0005] Therefore, there is a need for a solution that can provide a battery having low internal resistance and a low risk of short circuit, as well as a battery pack and a vehicle including the battery.

[0006] In order to prevent such electrical contact, a technique of applying an insulating coating to the ends of the positive and negative electrodes has been conventionally applied, but this technique has led to problems such as the insulating coating being destroyed or the separator being deformed during the process of bending the positive or negative electrodes, which reduces the effectiveness of the insulating coating. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the internal resistance of a cylindrical battery and effectively prevent internal short circuits.

[0008] Another object of the present invention is to provide an electrode assembly that can fully utilize the effect of an insulating coating even when the electrode is bent, and a battery including the electrode assembly.

[0009] It is yet another object of the present invention to provide an electrode assembly that can improve electrolyte impregnation through an insulating coating, and a battery including the same.

[0010] The technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0011] In order to achieve the above object, an electrode assembly according to one aspect of the present invention is an electrode assembly in which a core and an outer circumferential surface are defined by winding sheet-like first and second electrodes and a separator interposed between the first and second electrodes around an axis, and the first and second electrodes each include an uncoated portion at the long side end of the sheet-like electrode where an active material layer is not coated and which protrudes outward from the separator along the axial direction, and a coated portion in which an active material layer is coated in an area excluding the uncoated portion.

[0012] Preferably, the first electrode includes at least one insulating layer simultaneously covering at least a portion of the uncoated portion and at least a portion of the coated portion along the winding direction.

[0013] The uncoated portion is bent in the radial direction at a point spaced apart from the insulating layer in the axial direction.

[0014] The insulating layer may be thinner than the active material layer, and the insulating layer and the separator may be spaced apart from each other.

[0015] The insulating layer reinforces the strength of the portion of the first electrode that is covered by the insulating layer, so that when the uncoated portion is bent, the bending occurs in the region of the uncoated portion that is not covered by the insulating layer.

[0016] Even if the portion covered by the insulating layer is slightly deformed when the non-coating portion is bent, the insulating layer and the separator are slightly spaced apart, so that the separator can be prevented from being deformed due to the deformation of the insulating layer. Preventing the separator from being deformed maintains the effect of preventing contact between the first electrode and the second electrode.

[0017] A predetermined gap exists between the bent portion of the non-coating portion and the insulating layer in the axial direction.

[0018] The gap may be 0.2 mm or more, preferably 0.4 mm or more. If the gap is smaller than this, the insulating layer may be damaged or deformed when the non-coating portion is bent.

[0019] The gap may be 4 mm or less, preferably 1.5 mm or less. If the gap is larger than this, the effect of preventing damage or deformation of the insulating layer does not increase, and the effect of the insulating layer in supporting the uncoated portion during bending begins to decrease.

[0020] That is, the gap may be 0.2 to 4 mm, and preferably 0.4 to 1.5 mm.

[0021] At least a portion of the uncoated portion can itself be used as an electrode tab.

[0022] The uncoated portion of the first electrode has a first surface facing the core and a second surface facing the outer circumferential surface.

[0023] Preferably, the insulating layer may be provided on the first surface and the second surface.

[0024] The uncoated portion may be bent toward the core so that the first surface faces an end surface of the electrode assembly.

[0025] The region where the insulating layer covers the first surface may extend further toward the tip end of the uncoated portion than the region where the insulating layer covers the second surface.

[0026] When the uncoated portion is bent toward the core, a tensile force acts on the second surface along the axial direction, and a compressive force acts on the first surface along the axial direction. Therefore, by further reinforcing the insulating layer on the first surface, buckling of the uncoated portion can be further prevented.

[0027] Furthermore, if the height of the insulating layer covering the second surface is lower than the height of the insulating layer on the first surface, when the bent portions of adjacent uncoated areas facing the second surface overlap the second surface, the insulating layer is prevented from being interposed between the two adjacent uncoated areas, thereby further ensuring a conductive path between the overlapping uncoated areas.

[0028] According to the present invention, the uncoated portions are folded and overlapped in multiple layers in the axial direction, and no insulating layer may be formed on the surfaces where adjacent uncoated portions in the axial direction come into contact with each other.

[0029] As described above, according to the present invention, the strength of the uncoated portions is reinforced by the insulating layer, while sufficient electrical paths can be secured between the overlapping uncoated portions.

[0030] The tip of the insulating layer may be at least substantially the same height as the tip of the separation film.

[0031] The tip end of the insulating layer may extend further outward in the axial direction than the tip end of the separation film.

[0032] In other words, the one axial end of the insulating layer may have substantially the same height as the one axial end of the separation film or may be located outside the one axial end of the separation film.

[0033] More preferably, the one end of the insulating layer in the axial direction may be positioned at substantially the same height as the one end of the separation film in the axial direction.

[0034] In one embodiment, the uncoated portion may further protrude outside the insulating layer.

[0035] On the other hand, the landed portion does not have to protrude beyond the separation membrane in the axial direction.

[0036] Preferably, the first electrode may be a positive electrode.

[0037] In one embodiment, one end of the second electrode facing the insulating layer with the separation film interposed therebetween may not protrude outward beyond one end of the separation film.

[0038] Meanwhile, the land portion may include a sliding portion in which the thickness of the active material layer is reduced compared to a central region of the land portion.

[0039] Here, the sliding portion may be formed in a boundary region between the coated portion and the uncoated portion.

[0040] The sliding portion may be provided at one end of the first electrode and the other end of the second electrode.

[0041] The sliding portion of the ground portion provided on the first electrode and the sliding portion of the ground portion provided on the second electrode may be provided in opposite directions with respect to the axial direction.

[0042] The separation film may protrude outward beyond the other end of the first electrode and one end of the second electrode.

[0043] In one embodiment, the insulating layer may cover at least a portion of the sliding portion.

[0044] The insulating layer may cover the uncoated portion by 0.3 to 5 mm.

[0045] Preferably, the insulating layer covers the uncoated portion by 1.5 to 3 mm.

[0046] The insulating layer may cover the land portion by 0.1 to 3 mm.

[0047] Preferably, the insulating layer covers the land portion by 0.2 to 0.5 mm.

[0048] In another embodiment, at least a portion of the uncoated portion may be divided into a plurality of segments.

[0049] Preferably, at least a portion of the non-coating portion may be divided into a plurality of segments by a plurality of cutting grooves formed at intervals in the winding direction.

[0050] The segments may be folded radially.

[0051] During the process of bending the plain portion, a bending moment is concentrated at the lower end of the cut groove, so that a bend line can be formed at a position corresponding to the lower end of the cut groove.

[0052] The gap may be between a lower end of the kerf and the insulating layer.

[0053] The cutting groove may include a flat bottom portion, two separate side portions located on both sides of the bottom portion, and a rounded portion connecting the bottom portion and the side portions.

[0054] To improve electrolyte impregnation, an imaginary line along the axial edge of the insulating layer may overlap the rounded portion.

[0055] In order to improve electrolyte impregnation and minimize buckling when the uncoated portion is bent, the uncoated portion of the first electrode has a first surface facing the core and a second surface facing the outer peripheral surface, the region where the insulating layer covers the first surface extends further toward the tip end of the uncoated portion of the first electrode than the region where the insulating layer covers the second surface, and a virtual line along the axial end of the insulating layer formed on the second surface of the uncoated portion of the first electrode can overlap the rounded portion.

[0056] The plurality of segments may be folded toward the core and overlap each other in multiple layers along the axial direction.

[0057] In one embodiment, the uncoated portion of the first electrode and the uncoated portion of the second electrode may protrude in opposite directions relative to the axial direction.

[0058] Meanwhile, the length of the ground portion of the first electrode in the axial direction may be shorter than the length of the ground portion of the second electrode in the axial direction.

[0059] The ground portion provided on the first electrode may be located more inward in the axial direction than the ground portion provided on the second electrode.

[0060] The insulating layer may be an insulating coating layer or an insulating tape provided on the boundary area between the uncoated portion and the coated portion.

[0061] Preferably, the insulating layer may include a binder and an inorganic filler.

[0062] Preferably, the insulating layer may be porous.

[0063] In order to achieve the above object, a battery according to another aspect of the present invention includes the electrode assembly, a battery housing in which the electrode assembly is housed and which is electrically connected to one of the first electrode and the second electrode, a sealing body which seals an open end of the battery housing, and a terminal which is electrically connected to the other of the first electrode and the second electrode and has a surface exposed to the outside.

[0064] The battery may further include a first current collector plate electrically coupled to the uncoated portion of the first electrode.

[0065] The uncoated portion may be electrically coupled to the first current collector plate in a region of the entire area of ​​the uncoated portion that is not covered by the insulating layer.

[0066] The uncoated portion may be joined to the first current collecting plate by welding in a region of the entire area of ​​the uncoated portion that is not covered by the insulating layer.

[0067] In order to achieve the above object, a battery pack according to yet another aspect of the present invention includes a plurality of the above-described batteries and a pack housing that houses the plurality of batteries.

[0068] The above object is also achieved by a vehicle including the battery pack. [Effects of the Invention]

[0069] According to the present invention, the internal resistance of the battery can be dramatically reduced.

[0070] Furthermore, according to the present invention, electrical contact between the positive and negative electrodes of the electrode assembly can be more reliably prevented, thereby effectively preventing an internal short circuit in the battery.

[0071] Furthermore, according to the present invention, since the insulating layer supports the bending point of the non-coating portion, buckling that occurs when the non-coating portion is bent can be minimized.

[0072] Furthermore, according to the present invention, when the uncoated portion includes a plurality of segments separated by cutting grooves, the axial end of the insulating layer overlaps with the rounded portion of the cutting groove, thereby improving electrolyte impregnation.

[0073] The effects of the present invention are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

[0074] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in the drawings. [Brief explanation of the drawings]

[0075] [Figure 1] 1 is a perspective view of a cylindrical battery according to one embodiment of the present invention; [Figure 2] 1 is a longitudinal cross-sectional view of a cylindrical battery according to an embodiment of the present invention; [Figure 3] 1 is a perspective view of an electrode assembly included in a cylindrical battery according to an embodiment of the present invention; [Figure 4] 2 is a partial vertical cross-sectional view illustrating an arrangement structure of electrodes and a separator included in an electrode assembly according to an embodiment of the present invention. [Figure 5] 10 is a partial vertical cross-sectional view showing an arrangement structure of electrodes and a separator included in an electrode assembly according to another embodiment of the present invention. [Figure 6] 4 is a partial vertical cross-sectional view illustrating the arrangement of electrodes and separators included in an electrode assembly when an uncoated portion is folded according to an embodiment of the present invention. FIG. [Figure 7a] 10 is a partial plan view of an electrode illustrating the characteristics of the gap between the insulating layer and the kerf when the uncoated portion of the electrode includes multiple segments according to an embodiment of the present invention. FIG. [Figure 7b]10 is a partial plan view of an electrode showing the characteristics when the uncoated portion of the electrode includes a plurality of segments and the end of the insulating layer overlaps with the rounded portion of the cutting groove according to another embodiment of the present invention. FIG. [Figure 8] 1 is a perspective view showing an electrode assembly in a state where a segment is bent according to an embodiment of the present invention; [Figure 9] 1 is a partial vertical cross-sectional view showing the arrangement of electrodes and a separator included in an electrode assembly according to the prior art; [Figure 10] 1 is a graph showing power distribution in various short circuit cases in a battery. [Figure 11] 1 is a diagram illustrating a battery pack including a cylindrical battery according to an embodiment of the present invention. [Figure 12] 1 is a diagram illustrating a vehicle including a battery pack according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0076] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best explain the invention. Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention, and do not represent the entire technical ideas of the present invention, and therefore various equivalents and modifications that can be substituted therefor may exist at the time of filing this application.

[0077] In the description of the embodiment, the direction corresponding to the winding axis of the electrode assembly 10 is referred to as the axial direction (Z-axis). The axial direction (Z-axis) may correspond to the width direction of the sheet-like electrodes and separator.

[0078] In addition, the length direction (X axis) of the sheet-like electrodes and separator may correspond to the circumferential direction (X axis) surrounding the wound electrode assembly 10.

[0079] Furthermore, the normal direction (Y axis) of the surfaces of the sheet-like electrodes and separator may correspond to the radial direction (Y axis) of the wound electrode assembly 10 .

[0080] 1 to 3, a battery 1 according to one embodiment of the present invention includes an electrode assembly 10, a battery housing 20, a sealing body 30, and a terminal 40.

[0081] In addition to the above-mentioned components, the battery 1 may further include a first current collector plate 50 and / or an insulator 60 and / or an insulating gasket 70 and / or a second current collector plate 80 and / or a sealing gasket 90.

[0082] 1 to 3, the electrode assembly 10 includes a first electrode 11 having a first polarity, a second electrode 12 having a second polarity, a separator 13 interposed between the first electrode 11 and the second electrode 12, and an insulating layer 14 covering at least a portion of the first electrode 11.

[0083] The first electrode 11 is a positive electrode or a negative electrode, and the second electrode 12 is an electrode having the opposite polarity to the first electrode 11. In this embodiment, the first electrode 11 is a positive electrode, and the second electrode 12 is a negative electrode. The first electrode 11 and the second electrode 12 may be sheet-shaped. The electrode assembly 10 may have, for example, a jelly-roll structure. That is, the electrode assembly 10 may be manufactured by sequentially stacking the first electrode 11, the separator 13, the second electrode 12, and the separator 13 at least once, and winding the stack around a winding center C. In this case, the separator 13 may have an outermost winding turn portion on the outer periphery of the electrode assembly 10 for insulation from the battery housing 20.

[0084] The first electrode 11 and the second electrode 12 may include uncoated portions 11a and 12a at the long side edges where an active material layer is not coated. The first electrode 11 and the second electrode 12 may include coated portions 11b and 12b where an active material layer is coated in areas other than the uncoated portions 11a and 12a.

[0085] Specifically, the first electrode 11 includes a first electrode current collector and a first electrode active material layer coated on one or both sides of the first electrode current collector. The region where the first electrode active material layer is coated on the first electrode current collector is referred to as the coated portion 11b of the first electrode 11. An uncoated portion 11a where the first electrode active material layer is not coated may be present at one axial end of the first electrode current collector. At least a portion of the uncoated portion 11a itself serves as an electrode tab. That is, at least a portion of the wound turns of the uncoated portion 11a functions as the electrode tab of the first electrode 11. The uncoated portion 11a of the first electrode 11 is provided on the axial upper side of the electrode assembly 10 housed in the battery housing 20.

[0086] The second electrode 12 includes a second electrode current collector and a second electrode active material layer coated on one or both sides of the second electrode current collector. The area where the second electrode active material layer is coated on the second electrode current collector is referred to as the coated portion 12b of the second electrode 12. An uncoated portion 12a, where the second electrode active material layer is not coated, may be present at the other axial end of the second electrode current collector. At least a portion of the uncoated portion 12a itself serves as an electrode tab. That is, at least a portion of the wound turns of the uncoated portion 12a functions as an electrode tab of the second electrode 12. The uncoated portion 12a of the second electrode 12 is provided on the axial lower side of the electrode assembly 10 housed in the battery housing 20.

[0087] The uncoated portion 11a of the first electrode 11 and the uncoated portion 12a of the second electrode 12 may protrude in opposite directions. For example, referring to Figures 3 and 4, the uncoated portion 11a of the first electrode 11 may protrude upward in the axial direction of the electrode assembly 10, and the uncoated portion 12a of the second electrode 12 may protrude downward in the axial direction of the electrode assembly 10. As a result, the uncoated portion 11a of the first electrode and the uncoated portion 12a of the second electrode may protrude in opposite directions along the axial direction of the electrode assembly 10 toward the outside of the separator 13.

[0088] For ease of explanation, in FIG. 4, the thicknesses of the separator 13, the first electrode 11 and the second electrode 12 are exaggerated, and the length of the uncoated portion 11a is shown shorter than it actually is.

[0089] Meanwhile, the land portions 11b and 12b may include sliding portions where the thickness of the active material layer is reduced compared to the central region of the land portions 11b and 12b. For example, referring to FIG. 4, each of the first electrode 11 and the second electrode 12 may include a sliding portion, which is a region where the thickness of the active material layer is reduced, at one end or the other end.

[0090] The sliding phenomenon refers to a phenomenon in which the electrode active material-containing slurry spreads, resulting in less electrode active material being applied at the boundary region of the slurry application than at other regions of the boundary region, resulting in the slurry at the application boundary region having a generally inclined shape. Here, when the electrode is dried overall, the solvent contained in the slurry evaporates, reducing the volume of the slurry, which can further intensify the sliding phenomenon near the boundary between the region where the electrode active material is applied and the region where it is not applied.

[0091] The sliding portion may be formed in a boundary region between the ground portions 11b, 12b and the un-coated portions 11a, 12a. For example, the sliding portion may be provided at one end of the first electrode 11 and the other end of the second electrode 12. That is, the sliding portion of the ground portion 11b of the first electrode 11 and the sliding portion of the ground portion 12b of the second electrode 12 may be provided in opposite directions. For example, referring to FIG. 4, the sliding portion of the first electrode 11 may be formed at an upper side in the axial direction, and the sliding portion of the second electrode 12 may be formed at a lower side in the axial direction, which is the opposite direction.

[0092] Meanwhile, the axial length of the ground portion 11b of the first electrode 11 may be shorter than the axial length of the ground portion 12b of the second electrode 12. Furthermore, the ground portion 11b of the first electrode 11 may be located more inward in the axial direction than the ground portion 12b of the second electrode 12. For example, referring to FIG. 4, the axial length of the ground portion 12b of the second electrode 12 may be longer than the axial length of the ground portion 11b of the first electrode 11. As a result, the upper end of the ground portion 11b of the first electrode 11 is located lower than the upper end of the ground portion 12b of the second electrode 12, and the lower end of the ground portion 11b of the first electrode 11 is located higher than the lower end of the ground portion 12b of the second electrode 12. 4, the axial length of the ground portion 11b of the first electrode 11 may be shorter than the axial length of the area of ​​the ground portion 12b of the second electrode 12 excluding the sliding portion. This structure is intended to prevent the NP ratio of the positive electrode / negative electrode from decreasing below 100%, which would result in the deposition of lithium metal.

[0093] On the other hand, the ground portions 11b, 12b do not protrude further in the axial direction than the separation membrane 13. In other words, if the ground portions 11b, 12b protrude further in the axial direction than the separation membrane 13, the first electrode 11 and the second electrode 12 are more likely to come into contact with each other. This may cause an internal short circuit in the contact area, increasing the risk of fire. Therefore, it is important that the ground portions 11b, 12b do not protrude further in the axial direction than the separation membrane 13. In other words, it is desirable that the ground portions 11b, 12b are located inside the separation membrane 13 in the axial direction.

[0094] Meanwhile, in the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art without any limitations.

[0095] As an example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; and the stoichiometric coefficients x, y, and z are selected to maintain electroneutrality of the compound).

[0096] As another example, the positive electrode active material may be an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1).

[0097] In yet another example, the positive electrode active material may be a compound represented by the general chemical formula Li a M 1 x Fe1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality), or it can be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0098] Preferably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of primary particles.

[0099] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0100] As the separation membrane, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or by laminating these. As another example, the separation membrane can use a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc.

[0101] At least one surface of the separator may include a coating layer of inorganic particles. Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is interstitial volume between adjacent particles.

[0102] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0103] The electrolyte is A + B - where A + Li + , Na + , K. + and B - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 -, (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The anion comprises one or more anions selected from the group consisting of:

[0104] The electrolyte may be dissolved in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0105] To minimize the possibility of contact between the first electrode 11 and the second electrode 12, the first electrode 11 of the present invention may include at least one insulating layer 14 that simultaneously covers at least a portion of the uncoated portion 11a and at least a portion of the ground portion 11b. The insulating layer 14 may cover at least the boundary between the uncoated portion 11a and the ground portion 11b, and may also cover portions of the uncoated portion 11a and the ground portion 11b adjacent to the boundary.

[0106] The insulating layer 14 can effectively prevent electrical contact between the first electrode 11 and the second electrode 12. More specifically, it can effectively prevent electrical contact between the uncoated portion 11a of the first electrode 11 and the coated portion 12b of the second electrode 12.

[0107] The insulating layer 14 may be provided on at least one surface of the first electrode 11. For example, the insulating layer 14 may be provided on both surfaces of the first electrode 11. When viewed in the radial direction, a separation membrane 13 is located on both sides of the first electrode 11, and the second electrode 12 faces the first electrode 11 with the separation membrane 13 interposed therebetween. Therefore, in order to prevent electrical contact between the first electrode 11 and the second electrode 12 facing each other with the separation membrane 13 interposed therebetween, it is preferable that the insulating layer 14 be provided on both surfaces of the first electrode 11.

[0108] The insulating layer 14 may be provided on the entire region of the first electrode 11 that may face the landed portion 12b of the second electrode 12. For example, one axial end of the insulating layer 14 may be located at the same height as or outside one axial end of the separator 13. More specifically, referring to FIG. 4, one axial end of the insulating layer 14 may be located at the same height as one axial end of the separator 13. Alternatively, as shown in FIG. 5, one axial end of the insulating layer 14 may be located higher than one axial end of the separator 13.

[0109] Because the separator 13 protrudes in the axial direction between the first electrode 11 and the second electrode 12, electrical contact between the first electrode 11 and the second electrode 12 can be prevented to some extent. However, due to the possibility of the first electrode 11 or the second electrode 12 moving, such as meandering, inside the battery 1, it is difficult to eliminate the possibility that the second electrode 12 will be located near the end of the separator 13. Therefore, if the second electrode 12 is positioned up to the end of the separator 13 or protrudes beyond the end of the separator 13 due to the occurrence of such movement, electrical contact between the first electrode 11 and the second electrode 12 will be unavoidable. Alternatively, if the separator 13 is damaged for some reason, electrical contact between the first electrode 11 and the second electrode 12 will be unavoidable. Therefore, to prevent electrical contact between the first electrode 11 and the second electrode 12 even in such cases, it is preferable that the insulating layer 14 provided on the first electrode 11 extend to at least the same height as one end of the separator 13 or beyond that end.

[0110] However, if the insulating layer 14 covers the entire uncoated portion 11a of the first electrode 11, the uncoated portion 11a will not be able to function as an electrode tab. Therefore, the insulating layer 14 should cover only a portion of the uncoated portion 11a of the first electrode 11. In other words, the uncoated portion 11a has a shape that protrudes further outward from the insulating layer 14.

[0111] The insulating layer 14 may be an insulating coating layer or insulating tape provided on the boundary region between the uncoated portion 11a and the coated portion 11b. However, the form of the insulating layer 14 is not limited thereto, and any form that can be attached to the first electrode 11 while maintaining insulating properties may be employed in the present invention. Meanwhile, the insulating layer 14 may include a binder such as organic SBR and an inorganic filler such as SiO2 or Al2O3 to ensure insulating properties. Of course, the binder and inorganic filler may be other materials known in the art.

[0112] The insulating layer 14 may cover at least a portion of the uncoated portion 11a and at least a portion of the ground portion 11b simultaneously. For example, the insulating layer 14 may be provided on the boundary region between the ground portion 11b and the uncoated portion 11a. For example, the insulating layer 14 may cover at least a portion of the sliding portion.

[0113] For example, the insulating layer 14 may extend to a point about 0.3 to 5 mm from the boundary between the uncoated portion 11a and the coated portion 11b across the entire area of ​​the uncoated portion 11a of the first electrode 11. More preferably, the insulating layer 14 may extend to a point about 1.5 to 3 mm from the boundary between the uncoated portion 11a and the coated portion 11b across the entire area of ​​the uncoated portion 11a of the first electrode 11.

[0114] If the insulating layer 14 were not present, contact between the first electrode 11 and the second electrode 12 could cause an internal short circuit, so it is desirable that the insulating layer 14 extend to a position where electrical contact between the first electrode 11 and the second electrode 12 does not occur.

[0115] Meanwhile, the insulating layer 14 may extend to a point about 0.1 to 3 mm from the boundary between the uncoated portion 11a and the ground portion 11b across the entire area of ​​the ground portion 11b of the first electrode 11. More preferably, the insulating layer 14 may extend to a point about 0.2 to 0.5 mm from the boundary between the uncoated portion 11a and the ground portion 11b across the entire area of ​​the ground portion 11b of the first electrode 11.

[0116] If the insulating layer 14 covers a portion of the ground portion 11b of the first electrode 11, a capacity loss occurs in the battery, so it is necessary to minimize the length by which the insulating layer 14 covers the ground portion. However, since there is a possibility that the ground portion 11b of the first electrode 11 may come into contact with the second electrode 12, it is desirable that the insulating layer 14 cover at least a portion of the ground portion 11b of the first electrode 11 to prevent this.

[0117] 4, the separator 13 may protrude outward from the other end of the first electrode 11 and one end of the second electrode 12. Here, the one end refers to the upper end in the axial direction in the drawing, and the other end refers to the lower end in the axial direction in the drawing. Therefore, the separator 13 may protrude outward from the lower end of the first electrode 11 and from the upper end of the second electrode 12. Meanwhile, the separator 13 does not protrude beyond the upper end of the first electrode 11. This is because the upper end of the first electrode 11, i.e., the uncoated portion 11a, functions as an electrode tab provided on the first electrode 11. Similarly, the separator 13 does not protrude beyond the lower end of the second electrode 12. This is because the lower end of the second electrode 12, i.e., the uncoated portion 12a, functions as an electrode tab provided on the second electrode 12.

[0118] Meanwhile, one end of the second electrode 12 facing the insulating layer 14 across the separation membrane 13 may not protrude beyond one end of the separation membrane 13. For example, referring to FIG. 4, one end of the first electrode 11 is provided with the insulating layer 14, and one end of the second electrode 12 facing the insulating layer 14 is located inside the separation membrane 13. Therefore, even if one end of the first electrode 11 protrudes beyond the separation membrane 13, one end of the second electrode 12 is located inside the separation membrane 13, which significantly reduces the possibility of contact between the first electrode 11 and the second electrode 12.

[0119] 1 and 2, the battery housing 20 is a generally cylindrical container with an opening at its bottom end and is made of a conductive material such as metal. The material of the battery housing 20 may be, for example, aluminum. The bottom of the battery housing 20 with the opening is referred to as the open end. The side (outer periphery) and top of the battery housing 20 may be integrally formed. The top of the battery housing 20 (a surface perpendicular to the Z axis and parallel to the XY plane) has a generally flat shape. The top opposite the open end is referred to as the closed end. The battery housing 20 accommodates the electrode assembly 10 through an opening formed at its bottom, along with an electrolyte.

[0120] The battery housing 20 is electrically connected to the electrode assembly 10. The battery housing 20 may be electrically connected to one of the first electrode 11 and the second electrode 12. For example, the battery housing may be electrically connected to the second electrode 12 of the electrode assembly 10. In this case, the battery housing 20 may have the same polarity as the second electrode 12.

[0121] 2, the battery housing 20 may have a beading portion 21 and a crimping portion 22 formed at its lower end. The beading portion 21 is located below the electrode assembly 10. The beading portion 21 is formed by pressing around the outer periphery of the battery housing 20. The beading portion 21 prevents the electrode assembly 10, which has a size approximately corresponding to the width of the battery housing 20, from slipping out of an opening formed at the lower end of the battery housing 20, and may function as a support on which the sealing body 30 is placed.

[0122] The crimping portion 22 is formed below the beading portion 21. The crimping portion 22 is extended and bent to enclose the outer circumferential surface of the sealing body 30 disposed below the beading portion 21 and a part of the lower surface of the sealing body 30.

[0123] However, the present invention does not exclude the case where the battery housing 20 does not include such a beading portion 21 and / or a crimping portion 22. That is, in one embodiment of the present invention, if the battery housing 20 does not include the beading portion 21 and / or the crimping portion 22, the fixing of the electrode assembly 10 and / or the sealing of the battery housing 20 can be achieved, for example, by adding a component that can function as a stopper for the electrode assembly 10. Also, if the battery 1 of one embodiment of the present invention includes a sealing body 30, the fixing of the electrode assembly 10 and / or the sealing of the battery housing 20 can be achieved, for example, by adding a structure on which the sealing body 30 can be placed and / or by welding the battery housing 20 and the sealing body 30 together. That is, the sealing body 30 can seal the open end of the battery housing 20.

[0124] Referring to FIG. 2 , the sealing body 30 may be made of, for example, a metal material to ensure rigidity. The sealing body 30 may cover an open end formed at the bottom of the battery housing 20. That is, the sealing body 30 forms the bottom surface of the battery 1. In the battery 1 according to one embodiment of the present invention, the sealing body 30 does not have polarity even when made of a conductive metal material. "Not having polarity" means that the sealing body 30 is electrically insulated from the battery housing 20 and the terminal 40. Therefore, the sealing body 30 does not function as the positive terminal 40 or the negative terminal 20a. Therefore, the sealing body 30 does not need to be electrically connected to the electrode assembly 10 and the battery housing 20, and its material does not necessarily need to be a conductive metal.

[0125] When the battery housing 20 according to the embodiment of the present invention includes a beading portion 21, the sealing body 30 may be placed on the beading portion 21 formed on the battery housing 20. When the battery housing 20 according to the embodiment of the present invention includes a crimping portion 22, the sealing body 30 may be fixed by the crimping portion 22. A sealing gasket 90 may be interposed between the sealing body 30 and the crimping portion 22 of the battery housing 20 to ensure airtightness of the battery housing 20. Meanwhile, as described above, the battery housing 20 according to the embodiment of the present invention may not include the beading portion 21 and / or the crimping portion 22. In this case, the sealing gasket 90 may be interposed between the sealing body 30 and a structure for fixing the sealing body 30 provided on the open side of the battery housing 20 to ensure airtightness of the battery housing 20.

[0126] 1 and 2, the terminal 40 may be electrically connected to the other of the first electrode 11 and the second electrode 12. That is, the terminal 40 may have an opposite polarity to the battery housing 20. For example, the terminal 40 may be electrically connected to the first electrode 11 of the electrode assembly 10. The surface of the terminal 40 may be exposed to the outside.

[0127] The terminal 40 may be made of a conductive metal material. For example, the terminal 40 may pass through approximately the center of a closed end formed at the upper end of the battery housing 20. A portion of the terminal 40 may be exposed to the upper side of the battery housing 20, and the remaining portion may be located inside the battery housing 20. The terminal 40 may be fixed to the inner surface of the closed end of the battery housing 20 by, for example, riveting. The terminal 40 may penetrate the insulator 60 and be coupled to the first current collector 50 or the uncoated portion 11a of the first electrode 11. In this case, the terminal 40 may have a first polarity. Therefore, the terminal 40 may function as a first electrode terminal in the battery 1 according to an embodiment of the present invention. When the terminal 40 has this first polarity, the terminal 40 is electrically insulated from the battery housing 20, which has a second polarity. Electrical insulation between the terminal 40 and the battery housing 20 can be achieved in various ways. For example, insulation can be achieved by interposing an insulating gasket 70 (described later) between the terminal 40 and the battery housing 20. Alternatively, insulation can be achieved by forming an insulating coating layer on a portion of the terminal 40. Alternatively, a method of structurally firmly fixing the terminal 40 to prevent contact between the terminal 40 and the battery housing 20 can be applied. Alternatively, a combination of two or more of the above-mentioned methods can be applied.

[0128] 2, the first current collecting plate 50 may be coupled to the upper portion of the electrode assembly 10. For example, the first current collecting plate 50 may be coupled to the uncoated portion 11a of the first electrode 11 at the upper portion of the electrode assembly 10. The first current collecting plate 50 may be made of a conductive metal material. Although not shown, the first current collecting plate 50 may have a plurality of protrusions and recesses formed radially on its lower surface. If the protrusions and recesses are formed, the first current collecting plate 50 may be pressed against the uncoated portion 11a of the first electrode 11 to press into the protrusions and recesses.

[0129] The battery 1 according to another embodiment of the present invention may not include the first current collector plate 50. In this case, the uncoated portion 11a of the first electrode 11 may be electrically connected to the terminal 40 directly.

[0130] 2, the first current collecting plate 50 may be coupled to an end of the uncoated portion 11a of the first electrode 11. The coupling between the uncoated portion 11a of the first electrode 11 and the first current collecting plate 50 may be performed by, for example, laser welding. The laser welding may be performed by partially melting the base material of the first current collecting plate 50, and may be performed with solder interposed between the first current collecting plate 50 and the uncoated portion 11a. In this case, it is preferable that the solder has a lower melting point than the first current collecting plate 50 and the uncoated portion 11a. Meanwhile, in addition to laser welding, resistance welding, ultrasonic welding, etc. may be used, but the welding method is not limited thereto.

[0131] 5 and 6, the uncoated portion 11a may be bent in a first direction (toward the right in the drawings). The bent position of the uncoated portion 11a may be spaced a predetermined distance in the axial direction from the insulating layer 14. That is, a predetermined gap G may be provided between the bent position of the uncoated portion 11a and the leading end of the insulating layer 14.

[0132] The insulating layer 14 covering the first surface S1 and the second surface S2 of the uncoated portion 11a reinforces the rigidity of the base end of the uncoated portion 11a (near the boundary between the coated and uncoated portions). As shown in Figures 5 and 6, the tip end of the uncoated portion 11a has a cantilever-like structure. Therefore, when the tip end of the uncoated portion 11a is pressed toward the core (centripetal direction) to bend the uncoated portion 11a, a bending moment acts on the base end of the uncoated portion 11a. At this time, the insulating layer 14 reinforces the base end of the uncoated portion 11a, so the uncoated portion 11a is bent above the tip end of the insulating layer 14.

[0133] According to one embodiment of the present invention, the bent portion of the non-coating portion 11a is located at a predetermined gap G from the leading end of the insulating layer 14. If an excessively large bending moment is applied to the insulating layer 14 when the non-coating portion 11a is bent, the insulating layer 14 itself may be deformed or damaged. As a result, the insulating layer 14 may not be positioned where it should be, increasing the possibility of the first electrode 11 and the second electrode 12 coming into contact with each other.

[0134] Therefore, in one embodiment of the present invention, when the non-coating portion 11a is bent in the radial direction, the bent portion is spaced a predetermined gap G from the insulating layer 14.

[0135] 5 and 6, the thickness of the insulating layer 14 is thinner than the thickness of the active material layer (covered portion 11b). This leaves a small gap between the insulating layer 14 and the separator 13. Therefore, even if a portion of the insulating layer 14 is deformed when the uncovered portion 11a is bent, this deformation of the insulating layer 14 does not immediately affect the separator 13. This allows the separator 13 to maintain its axial extension as designed, and prevents contact between the first electrode 11 and the second electrode 12.

[0136] The insulating layer 14 is provided on both the first surface S1 and the second surface S2 of the first electrode 11, and the uncoated portion 11a is bent toward the core as viewed from the first surface S1. As a result, the first surface S1 of the first electrode 11 receives a compressive force, and the second surface S2 receives a tensile force. Buckling is more likely to occur when a compressive force is applied to an offset position in the axial direction of the cantilever. Therefore, in one embodiment of the present invention, as shown in FIG. 6, the insulating layer 14 coated on the first surface S1 of the first electrode 11 covers a longer portion of the uncoated portion 11a in the axial direction than the insulating layer 14 on the second surface S2, thereby effectively preventing buckling of the uncoated portion 11a.

[0137] Furthermore, when uncoated portion 11a is bent toward the core, second surface S2 of uncoated portion 11a comes into contact with first surface S1 of another uncoated portion 11a disposed further distally. Therefore, by positioning the height of the tip of insulating layer 14 coated on second surface S2 of uncoated portion 11a lower than that of first surface S1, it is possible to maximize the contact area when adjacent uncoated portions 11a overlap.

[0138] On the other hand, when folding the plain portion 11a, the folding position can be accurately controlled and the plain portion 11a can be made up of a plurality of cut pieces so that the plain portion 11a is not folded neatly and wrinkles do not occur.

[0139] 7a and 8, cutting grooves TL may be formed at the tip of the uncoated portion 11a by notching or trimming at intervals along the circumferential direction (X-axis). In this case, the uncoated portion 11a has a shape in which a plurality of segments T are provided along the length direction of the first electrode 11. Of course, when the uncoated portion 11a is cut at regular intervals, the cutting lines are also considered to be a type of cutting groove TL.

[0140] The shape of the segment T may be various, such as an isosceles trapezoid, a semi-ellipse, a semi-circle, a rectangle, a square, an isosceles triangle, an equilateral triangle, etc., but in this embodiment, a substantially rectangular shape is exemplified.

[0141] With the divided segment T formed in this manner, when the leading end of the uncoated portion 11a is pressed radially in an attempt to fold the uncoated portion 11a, the uncoated portion 11a is folded along the fold line BL connecting the lower ends of the cut grooves TL. In other words, when the cut grooves TL are formed to fold the uncoated portion 11a, the folding is guided by the lower ends of the uncoated portion T. This allows the position of the fold line BL of the uncoated portion 11a to be accurately controlled.

[0142] Furthermore, when the divided pieces T are formed, the divided pieces T are folded individually when they are folded, which significantly reduces the possibility of problems such as the plain portion 11a being wrinkled while being folded.

[0143] According to one embodiment, the gap G may be the distance between the bending line BL, that is, the lower end of the cutting groove TL, and the leading end of the insulating layer 14 .

[0144] The gap G may be 0.2 to 4 mm. If the gap is smaller than 0.2 mm, the insulating layer 14 may be damaged or deformed during the bending of the uncoated portion 11a. If the gap is larger than 4 mm, the damage prevention effect of the insulating layer 14 does not increase any further, and the effect of the insulating layer 14 in supporting the uncoated portion during bending begins to decrease.

[0145] The gap G may more preferably be 0.4 to 1.5 mm.

[0146] In another embodiment of the present invention, the edge position of the insulating layer 14 can be adjusted based on the position of the lower end of the cutting groove TL in order to improve the impregnation of the electrolyte.

[0147] 7b is a partial plan view showing a modified structure of the first electrode 11 in which the end of the insulating layer 14 is extended to the bottom end of the cutting groove TL in consideration of the impregnation of the electrolyte. The structure shown in the figure can also be applied to the second electrode 12.

[0148] 7b, the cut groove TL corresponds to a space created when the uncoated portion 11a of the first electrode 11 is removed. Preferably, the cut groove TL includes a flat bottom portion A1, side portions A3 of the divided piece T located on both sides of the cut groove TL, and a rounded portion A2 smoothly connecting the bottom portion A1 and the side portions A3. The bottom portion A1 may be approximately parallel to the winding direction of the first electrode 11.

[0149] In the partially enlarged view of FIG. 7b, the symbols A2a and A2b respectively indicate the upper and lower end positions of the rounded portion A2, and BL indicates a bending line.

[0150] The radius of curvature of the rounded portion A2 may be greater than 0 mm and less than or equal to 0.5 mm, preferably greater than 0 mm and less than or equal to 0.1 mm, and more preferably 0.01 mm to 0.05 mm. When the radius of curvature of the rounded portion A2 satisfies the above range, cracks can be prevented from occurring at the bottom of the severance groove TL while the first electrode 11 is traveling during a winding process, etc. In particular, when the uncoated portion 11a is made of aluminum, cracks can be prevented from occurring at the bottom of the severance groove TL even when the first electrode 11 is traveling at a speed of 100 mm / sec or more under a tension of 300 gf or more during a winding process, etc.

[0151] The rounded portion A2 also relieves the stress that occurs near the bending line BL when the pieces T located on both sides of the cutting groove TL are bent, thereby effectively preventing damage to the insulating layer 14 and / or the ground portion 11b due to the bending stress.

[0152] 7b, the end of the insulating layer 14 may extend to the lower end of the cutting groove TL. Preferably, the end of the insulating layer 14 may be extended to a point where it overlaps with the rounded portion A2 in the axial direction. "The end of the insulating layer 14 overlaps with the rounded portion A2" means that, when an imaginary line is drawn along the end of the insulating layer 14, the imaginary line passes through the region between the upper end position A2a and the lower end position A2b of the rounded portion A2.

[0153] The fold line BL of the divided segment T may be formed in a region between the upper end position A2a and the lower end position A2b of the rounded portion A2, and may be substantially spaced from the end of the insulating layer 14. Of course, depending on the manner in which the force for bending the divided segment T is applied, the fold line BL may be formed at a position higher than the upper end position A2a of the rounded portion A2.

[0154] The end of the insulating layer 14 facing the kerf groove TL in the axial direction has a recessed structure toward the coated portion 11b according to the shape of the bottom A1 of the kerf groove TL. This structure can be formed by forming the insulating layer 14 on the uncoated portion 11a and then notching the uncoated portion 11a to form the divided piece T. That is, when the uncoated portion 11a is notched, a portion of the insulating layer 14 corresponding to the bottom A1 of the kerf groove TL can also be notched.

[0155] When the end of the insulating layer 14 extends axially so as to overlap the rounded portion A2 of the cut groove TL, it has the effect of improving electrolyte impregnation. That is, as shown in Fig. 8, when the electrode assembly 10 in which the segment pieces T are bent toward the core is inserted into the battery housing 20 and liquid electrolyte EL is injected, the electrolyte EL flows into the electrode assembly 10 through the cut groove TL between the segment pieces T. At this time, because the end of the insulating layer 14 overlaps the rounded portion A2 of the cut groove TL, the distance the electrolyte EL travels to the insulating layer 14 is short, and the insulating layer 14 comes into direct contact with the electrolyte EL.

[0156] Preferably, the insulating layer 14 includes an inorganic filler such as Al2O3 or SiO2 along with a binder. The inorganic filler is composed of particles. The particles are bound together by the binder, forming pores between the particles. To form the pores, the volume contents of the binder and inorganic filler can be adjusted. For example, increasing the volume content of the inorganic filler relative to the volume content of the binder increases the porosity of the insulating layer 14. The volume content of the binder relative to the total volume of the binder and inorganic filler can be 50% or less, preferably 40% or less, and more preferably 30% or less. The desired volume contents of the binder and inorganic filler to impart porosity to the insulating layer 14 can be easily determined through repeated experiments.

[0157] When the insulating layer 14 is porous, the surface of the insulating layer 14 has better wettability with respect to the electrolyte than the surface of the uncoated portion 11a of the metal material. Therefore, the electrolyte impregnated inside the insulating layer 14 near the bottom A1 and rounded portion A2 of the kerf groove TL quickly passes through the insulating layer 14 through the pores of the insulating layer 14 and reaches the coated portion 11b. In this way, the overlapping structure of the end of the porous insulating layer 14 and the lower end of the kerf groove TL provides an advantage in terms of electrolyte impregnation.

[0158] 5, when the length of the insulating layer 14 formed on the first surface S1 of the uncoated portion 11a is longer than the length of the insulating layer 14 formed on the second surface S2, the end of the insulating layer 14 formed on the first surface S1 may overlap the rounded portion A2 of the kerf groove TL. On the other hand, the end of the insulating layer 14 formed on the second surface S2 may overlap the rounded portion A2 of the kerf groove TL, or may be located at approximately the same position as or below the bottom A1 of the kerf groove TL.

[0159] 2 and 8, the first current collector plate 50 may be coupled to a coupling surface formed by bending an end (portion) of the uncoated portion 11a of the first electrode 11 in a direction parallel to the first current collector plate 50. The coupling surface may have a structure in which the end (or portion) of the uncoated portion 11a is stacked in multiple layers in the axial direction. The bending direction of the uncoated portion 11a may be, for example, toward the winding center C of the electrode assembly 10. When the uncoated portion 11a has such a folded shape, the space occupied by the uncoated portion 11a is reduced, thereby improving energy density. Furthermore, the increased coupling area between the uncoated portion 11a and the first current collector plate 50 may improve coupling strength and reduce resistance.

[0160] 2, the insulator 60 may be provided between the upper end of the electrode assembly 10 and the inner surface of the battery housing 20, or between the first current collecting plate 50 coupled to the upper portion of the electrode assembly 10 and the inner surface of the battery housing 20. The insulator 60 prevents contact between the uncoated portion 11a of the first electrode 11 and the battery housing 20 and / or between the first current collecting plate 50 and the battery housing 20. That is, the insulator 60 is accommodated inside the battery housing 20 and configured to cut off electrical connection between the uncoated portion 11a of the first electrode 11 and the battery housing 20. Therefore, the insulator 60 may be made of a material having insulating properties. For example, the insulator 60 may include a polymer material.

[0161] The insulating gasket 70 is interposed between the battery housing 20 and the terminal 40 to prevent contact between the battery housing 20 and the terminal 40, which have opposite polarities. That is, the insulating gasket 70 cuts off the electrical connection between the battery housing 20 and the terminal 40. As a result, the upper surface 20a of the battery housing 20, which has a substantially flat shape, can function as the second electrode terminal of the battery 1.

[0162] The second current collecting plate 80 may be coupled to a lower portion of the electrode assembly 10. The second current collecting plate 80 may be made of a conductive metal material. The second current collecting plate 80 may be connected to the uncoated portion 12a of the second electrode 12. The second current collecting plate 80 may also be electrically connected to the battery housing 20. The second current collecting plate 80 may be interposed and fixed between the inner surface of the battery housing 20 and a sealing gasket 90. Preferably, the second current collecting plate 80 may be welded to the inner wall surface of the battery housing 20, for example, the inner circumferential surface of the beading portion 21.

[0163] Although not shown, the second current collecting plate 80 may have a plurality of projections and recesses formed radially on one surface thereof. When projections and recesses are formed, the second current collecting plate 80 may be pressed against the projections and recesses to press the projections into the uncoated portion 12a of the second electrode 12.

[0164] The second current collecting plate 80 may be coupled to an end of the uncoated portion 12a of the second electrode 12. The uncoated portion 12a of the second electrode 12 may be divided into a plurality of segments T, similar to the uncoated portion 11a of the first electrode 11. The uncoated portion 12a of the second electrode 12 may be coupled to the second current collecting plate 80 by, for example, laser welding. The laser welding may be performed by partially melting the base material of the second current collecting plate 80, and may be performed with solder interposed between the second current collecting plate 80 and the uncoated portion 12a. In this case, it is preferable that the solder has a lower melting point than the second current collecting plate 80 and the uncoated portion 12a. Meanwhile, in addition to laser welding, resistance welding, ultrasonic welding, etc. may be used, but the welding method is not limited thereto.

[0165] The second current collector plate 80 may be coupled to a coupling surface formed by bending an end (or a segment) of the uncoated portion 12a of the second electrode 12 in a direction parallel to the second current collector plate 80. As shown in FIG. 8 , the coupling surface may have a structure in which the end (or segment) of the uncoated portion 12a is stacked in multiple layers in the axial direction. The uncoated portion 12a of the second electrode 12 may be bent, for example, toward the winding center C of the electrode assembly 10. When the uncoated portion 12a of the second electrode 12 has such a bent shape, the space occupied by the uncoated portion 12a is reduced, thereby improving energy density. Furthermore, the increased coupling area between the uncoated portion 12a and the second current collector plate 80 may improve coupling strength and reduce resistance.

[0166] The sealing gasket 90 may be substantially ring-shaped and surround the seal body 30. The sealing gasket 90 may simultaneously cover the bottom, top, and side surfaces of the seal body 30. The radial length of the portion of the sealing gasket 90 covering the top surface of the seal body 30 may be shorter or equal to the radial length of the portion of the sealing gasket 90 covering the bottom surface of the seal body 30. If the radial length of the portion of the sealing gasket 90 covering the top surface of the seal body 30 is too long, the sealing gasket 90 may press against the second current collector plate 80 during a sizing process in which the battery housing 20 is compressed vertically, potentially damaging the second current collector plate 80 or the battery housing 20. Therefore, it is necessary to maintain the radial length of the portion of the sealing gasket 90 covering the top surface of the seal body 30 at a small constant level.

[0167] Referring to Fig. 8, the electrode assembly 10 according to an embodiment of the present invention may have a structure in which at least a portion of the uncoated portions 11a, 12a is bent toward the core. For example, referring to Figs. 7a and 8, at least a portion of the uncoated portions 11a, 12a may be divided into a plurality of segments T. Here, the plurality of segments T may have a structure in which the segments T are bent toward the core and overlap each other in multiple layers along the axial direction. For example, the plurality of segments T may be notched by a laser. The segments T may be formed by a known metal foil cutting process such as ultrasonic cutting or punching.

[0168] To prevent damage to the active material layer during the bending process of the plain portions 11a and 12a, a predetermined gap may be provided between the lower end of the cut groove TL between the divided pieces and the active material layer. This is because, when the plain portions 11a and 12a are bent, stress is concentrated on the fold line BL provided near the lower end of the cut groove. The gap is preferably 0.2 to 4 mm. The gap may be 0.2 mm or more. Preferably, the gap may be 0.4 mm or more. More preferably, the gap may be 0.5 mm or more. Most preferably, the gap may be 0.7 mm or more. Alternatively, the gap may be 4 mm or less. Preferably, the gap may be 3 mm or less. More preferably, the gap may be 1.5 mm or less. Even more preferably, the gap may be 1.2 mm or less. Most preferably, the gap may be 0.9 mm or less. If the gap is adjusted to the above range, it is possible to prevent the active material layer near the lower end of the cut groove from being damaged by stress generated during the bending process of the non-coating portions 11a and 12a.

[0169] The lower end of the cutting groove of the divided piece T is a position where bending of the divided piece T can be induced. That is, when bending the divided piece T, the bending resistance of the lower end of the divided piece T cut by the cutting groove TL is reduced, and bending is induced at that portion. That is, it can be said that the bending portion is the lower end of the divided piece T or a region adjacent thereto. The insulating layer 14 has the effect of thickening the thin plain portion 11a, and therefore when the plain portion 11a is bent, the strength of the section of the plain portion 11a covered with the insulating layer 14 is reinforced, and the plain portion 11a below the bending guide portion can be supported so that it does not bend.

[0170] Furthermore, since the insulating layer 14 covers the boundary between the uncoated portion 11a and the coated portion 11b, when the uncoated portion 11a is bent, the strength of the boundary area is reinforced, thereby reducing or preventing unintended deformation in the relevant area.

[0171] The bending direction of the uncoated portions 11a, 12a may be, for example, a direction toward the winding center C of the electrode assembly 10. When the uncoated portions 11a, 12a have such a bent shape, the space occupied by the uncoated portions 11a, 12a is reduced, thereby improving energy density. Furthermore, the increased bonding area between the uncoated portions 11a, 12a and the current collector plates 50, 80 can improve bonding strength and reduce resistance.

[0172] 6 and 8, the uncoated portion 11a of the first electrode 11 may be bent in one direction. For example, in FIG. 6, the +X direction may be the direction toward the core. When the uncoated portion 11a is bent toward the core in this manner, the uncoated portion 11a of one first electrode 11 may overlap the uncoated portion 11a of an adjacent first electrode 11 across two separators 13 in the radial direction. That is, when the uncoated portion 11a is located in the n-th winding turn of the first electrode 11, the first surface S1 of the uncoated portion 11a may overlap the second surface S2 of the uncoated portion 11a located in the n-1-th winding turn of the first electrode 11. Here, the n-1-th winding turn is closer to the winding center than the n-th winding turn. The insulating layer 14 on the first surface S1 extends to a position higher than the second surface S2. Therefore, the portion of the insulating layer 14 on the first surface S1 formed higher than the insulating layer 14 on the second surface S2 reduces the possibility that the first electrode 11 will come into contact with the adjacent second electrode 12 on the core side. In other words, the insulating layer 14 formed on the first surface S1 increases the insulating gap IG that exists between the ends of the first electrode 11 and the second electrode 12, thereby preventing short circuits between the electrodes.

[0173] 6, the leading edge of the insulating layer 14 may be positioned lower on the second surface S2 of the uncoated portion 11a, which is the surface opposite to the first surface S1 facing the core side, than on the first surface S1. Therefore, the exposed uncoated portion 11a on the surface opposite to the surface facing the core side may be in electrical contact with the uncoated portion 11a of the adjacent first electrode 11 or the first current collector plate 50. The overlapping uncoated portions 11a may be electrically connected to the first current collector plate 50 by welding or other methods. The welding may be, for example, laser welding. The laser welding may be performed by partially melting the base material of the first current collector plate 50, and may be performed with solder interposed between the first current collector plate 50 and the uncoated portion 11a. In this case, the solder preferably has a lower melting point than the first current collector plate 50 and the uncoated portion 11a. Meanwhile, in addition to laser welding, resistance welding, ultrasonic welding, etc. may be used, but the welding method is not limited to these.

[0174] In this way, the insulating layer 14 covering the uncoated portion 11a of the first electrode 11 may cover different areas on the centripetal surface and the centrifugal surface of the uncoated portion 11a. For example, the area where the insulating layer 14 covers the centripetal surface may extend to a higher position (closer to the tip of the uncoated portion) than the area where the insulating layer 14 covers the centrifugal surface.

[0175] FIG. 9 is a cross-sectional view of an electrode assembly 10 according to a comparative example of the present invention, which does not include an insulating layer 14. Referring to FIG. 9, a separate insulating layer 14 is not provided at the boundary between the uncoated portion 11a and the coated portion 11b of the first electrode 11. With this structure, if the first electrode 11 or the second electrode 12 moves due to meandering or other reasons, the second electrode 12 may be positioned at the end of the separator 13 or may protrude beyond the end of the separator 13, resulting in electrical contact between the first electrode 11 and the second electrode 12. Furthermore, unlike the embodiment, the structure of the comparative example has weak rigidity at the base end of the uncoated portion 11a, resulting in very low buckling resistance, which may lead to buckling of the base end of the uncoated portion 11a. Alternatively, if the separator 13 is damaged for some reason, electrical contact between the first electrode 11 and the second electrode 12 may occur. In this case, in the electrode assembly 10 having the structure shown in FIG. 9, an internal short circuit is unavoidable due to electrical contact between the first electrode 11 and the second electrode 12, increasing the risk of fire.

[0176] 10 is a graph illustrating power distribution in various short circuit cases in the battery 1. Referring to FIG. 10, the following four short circuit cases can be assumed to occur in the battery 1.

[0177] (i) when the grounded portion of the positive electrode and the grounded portion of the negative electrode are in electrical contact, (ii) when the grounded portion of the positive electrode and the uncoated portion of the negative electrode are in electrical contact, (iii) when the grounded portion of the negative electrode and the uncoated portion of the positive electrode are in electrical contact, and (iv) when the uncoated portion of the positive electrode and the uncoated portion of the negative electrode are in electrical contact.

[0178] 10, it can be seen that the power is highest in case (iii) where the grounded portion of the negative electrode and the uncoated portion of the positive electrode are in electrical contact. That is, in case (iii) where the grounded portion of the negative electrode and the uncoated portion of the positive electrode are in electrical contact, the possibility of fire is very high. This is because the resistance is very low and the short-circuit current is large, which causes a rapid rise in temperature.

[0179] Therefore, when considering the structure of the electrode assembly 10 of the present invention, a structure that can prevent electrical contact between the coated portion of the negative electrode and the uncoated portion of the positive electrode is required.

[0180] After extensive research, the inventors have found that providing an insulating layer 14 on at least a portion of the uncoated portion of the positive electrode can effectively prevent electrical contact with the coated portion of the negative electrode, thereby completing the present invention. That is, the first electrode 11 can be a positive electrode. However, the first electrode 11 is not necessarily limited to a positive electrode and can also be a negative electrode. Furthermore, the present invention does not exclude the second electrode 12 from being provided with an insulating layer 14. That is, the insulating layer 14 can be provided on both the positive electrode and the negative electrode. In this case, all possible short-circuit cases can be prevented.

[0181] Desirably, the battery may be, for example, one having a form factor ratio (defined as the diameter of the battery divided by its height, ie, the ratio of height (H) to diameter (Φ)) greater than about 0.4.

[0182] Here, the term "form factor" refers to a value indicating the diameter and height of a battery. A battery according to an embodiment of the present invention may be, for example, a 46110 battery, a 4875 battery, a 48110 battery, a 4880 battery, or a 4680 battery. In the form factor number, the first two digits indicate the diameter of the cell, and the remaining digits indicate the height of the battery.

[0183] A battery according to one embodiment of the present invention may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0184] Another embodiment of the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0185] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436.

[0186] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0187] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0188] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. 1865 batteries have a diameter of approximately 18 mm and a height of approximately 65 mm, resulting in a form factor ratio of approximately 0.277. 2170 batteries have a diameter of approximately 21 mm and a height of approximately 70 mm, resulting in a form factor ratio of approximately 0.300.

[0189] The batteries according to the above-described embodiments can be used to manufacture battery packs.

[0190] FIG. 11 is a diagram schematically illustrating the configuration of a battery pack according to an embodiment of the present invention.

[0191] 11, a battery pack 3 according to one embodiment of the present invention includes an assembly of electrically connected batteries 1 and a pack housing 2 that accommodates the assembly. The batteries 1 are the batteries according to the above-described embodiments. For convenience of illustration, components such as bus bars for electrically connecting the batteries 1 to each other, a cooling unit, and external terminals 40 are not shown.

[0192] The battery pack 3 may be mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0193] FIG. 12 is a diagram illustrating a vehicle including the battery pack 3 of FIG.

[0194] 12, an automobile 5 according to an embodiment of the present invention includes a battery pack 3 according to an embodiment of the present invention. The automobile 5 operates by receiving a supply of power from the battery pack 3 according to an embodiment of the present invention.

[0195] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims. [Explanation of symbols]

[0196] 5. Automobiles 10 Electrode assembly 11 1st electrode 12 Second electrode 13 Separation membrane 14 Insulating layer 20 Battery Housing 21 Beading section 22 Crimping section 30 Sealed body 40 terminals 50 First current collector plate 60 Insulator 70 Insulating gasket 80 Second current collector plate 90 Sealing Gasket

Claims

1. An electrode assembly in which a core and an outer circumferential surface are defined by winding sheet-like first and second electrodes and a separator interposed between the first and second electrodes around an axis, The first electrode and the second electrode each include: a plain portion on the long side edge of the sheet-like material that is not coated with an active material layer and that protrudes outward from the separator along the axial direction; a coated portion in which an active material layer is coated on an area other than the uncoated portion; Including, the first electrode includes at least one insulating layer simultaneously covering at least a portion of the uncoated portion and at least a portion of the coated portion along the winding direction, the uncoated portion is bent in the radial direction at a point spaced apart from the insulating layer in the axial direction, the insulating layer is thinner than the active material layer, At least a portion of the uncoated portion is divided into a plurality of segments by a plurality of cutting grooves formed at intervals in the winding direction, and the segments are bent in the radial direction so that ends of the segments face the core, The cutting groove includes a flat bottom portion, two side portions of the cutting groove located on both sides of the bottom portion, and a round portion connecting the bottom portion and the side portions.

2. The electrode assembly according to claim 1 , wherein a predetermined gap exists between the bent portion of the non-coating portion and the insulating layer in the axial direction.

3. the insulating layer is provided on both sides of the uncoated portion of the first electrode, the uncoated portion has a first surface facing the core and a second surface facing the outer circumferential surface, and is bent so that the first surface faces an end surface of the electrode assembly; The electrode assembly according to claim 1 , wherein the region of the insulating layer covering the first surface extends further toward the tip end of the non-coating portion than the region of the insulating layer covering the second surface.

4. The non-coating portion is folded and overlapped in multiple layers in the axial direction, 4. The electrode assembly according to claim 3, wherein no insulating layer is formed on the surfaces where the uncoated portions adjacent in the axial direction are in contact with each other.

5. The electrode assembly according to claim 1 , wherein a tip end of the insulating layer extends further outward in the axial direction than a tip end of the separator.

6. An electrode assembly as described in claim 1, wherein a predetermined gap exists between the lower end of the cutting groove and the insulating layer.

7. An electrode assembly as described in claim 6, wherein a virtual line along the axial end of the insulating layer overlaps with the round portion.

8. the uncoated portion of the first electrode has a first surface facing the core and a second surface facing the outer circumferential surface, a region of the insulating layer covering the first surface extends further toward a tip end of the uncoated portion of the first electrode than a region of the insulating layer covering the second surface, The electrode assembly according to claim 7 , wherein an imaginary line along an end of the insulating layer in the axial direction formed on the second surface of the uncoated portion of the first electrode overlaps with the rounded portion.

9. The electrode assembly according to claim 1 , wherein the one axial end of the insulating layer is positioned at substantially the same height as the one axial end of the separator.

10. The electrode assembly of claim 1 , wherein one end of the second electrode facing the insulating layer with the separator interposed therebetween does not protrude outward beyond the one end of the separator.

11. The electrode assembly of claim 1 , wherein the land portion includes a sliding portion at one end in the axial direction, the active material layer having a thickness that is reduced compared to a central region of the land portion.

12. 12. The electrode assembly of claim 11, wherein the sliding portion is provided at one end of the first electrode and the other end of the second electrode, and the sliding portion of the ground portion provided at the first electrode and the sliding portion of the ground portion provided at the second electrode are provided in opposite directions with respect to the axial direction.

13. The electrode assembly according to claim 11 , wherein the insulating layer covers at least a portion of the sliding portion.

14. 2. The electrode assembly of claim 1, wherein the insulating layer covers the uncoated portion by 0.3 to 5 mm and the insulating layer covers the coated portion by 0.1 to 3 mm.

15. The uncoated portion of the first electrode and the uncoated portion of the second electrode protrude in opposite directions from each other, a length in the axial direction of the ground portion provided on the first electrode is shorter than a length in the axial direction of the ground portion provided on the second electrode; The electrode assembly according to claim 1 , wherein the grounded portion of the first electrode is located more inward in the axial direction than the grounded portion of the second electrode.

16. The electrode assembly according to claim 1 , wherein the insulating layer is an insulating coating layer or an insulating tape provided on a boundary area between the uncoated portion and the coated portion.

17. 10. The electrode assembly according to claim 2, wherein the gap is 0.2 to 4 mm.

18. an electrode assembly in which a core and an outer circumferential surface are defined by winding sheet-like first and second electrodes and a separator interposed between the first and second electrodes around an axis, wherein the first and second electrodes each have a long side end portion of the sheet-like electrode that is not coated with an active material layer, an uncoated portion that protrudes outward from the separator along the axial direction, and a coated portion in which an active material layer is formed in an area excluding the uncoated portion, the first electrode including at least one insulating layer simultaneously covering at least a portion of the uncoated portion and at least a portion of the coated portion along the winding direction, the uncoated portion being bent in a radial direction at a point spaced apart from the insulating layer in the axial direction, and the insulating layer being thinner than the active material layer; a battery housing that houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode; a seal that seals the open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode and having a surface exposed to the outside; a first current collector plate electrically coupled to the uncoated portion of the first electrode, the uncoated portion of the first electrode is joined to the first current collecting plate by welding in a region of the entire uncoated portion of the first electrode that is not covered by the insulating layer; At least a portion of the uncoated portion is divided into a plurality of segments by a plurality of cutting grooves formed at intervals in the winding direction, and the segments are bent in the radial direction so that ends of the segments face the core, The cutting groove includes a flat bottom portion, side portions of the cut pieces located on both sides of the bottom portion, and a round portion connecting the bottom portion and the side portions.

19. A battery pack comprising the battery of claim 18.

20. 20. A motor vehicle comprising the battery pack of claim 19.

Images