Electrode assembly, cylindrical battery cell, battery pack, and vehicle

Abstract

Provided are an electrode assembly, a cylindrical battery cell, a battery pack, and a vehicle. An electrode assembly according to an embodiment of the present disclosure is a jelly-roll type having a structure in which a first electrode and a second electrode each having a sheet shape and a separator interposed between the first electrode and the second electrode are wound in one direction. Each of the first electrode and the second electrode includes an uncoated portion that is not coated with an active material layer and is formed on a longer edge end portion, and a coated portion that is coated with an active material layer and is formed on an area other than the uncoated portion. The first electrode includes at least one insulating layer that covers at least a portion of the uncoated portion and at least a portion of the coated portion at the same time.

Description

Technical Field

[0001] This disclosure relates to electrode assemblies, cylindrical secondary batteries, and battery packs and vehicles including the same. Background Technology

[0002] In cylindrical secondary batteries, for higher current collection efficiency, the battery can can use a wound-core type electrode assembly with the following shape: wherein the positive terminal and the negative terminal extend on the upper and lower sides of the battery can, respectively, in the height direction of the battery can.

[0003] In this structure, movement of the positive or negative electrode is possible, such as serpentine movement. In this case, there is a possibility that the end of the positive or negative electrode may move towards the end of the separator. Therefore, when the positive or negative electrode is positioned at the end of the separator or protrudes further outward than the end of the separator due to movement such as serpentine movement, electrical contact occurs between the positive and negative electrodes. Alternatively, electrical contact may occur between the positive and negative electrodes when the separator is damaged for some reason. Therefore, a short circuit may occur within the battery. A short circuit occurring inside the battery may cause the battery to overheat or explode. Therefore, there is a need to provide an insulating member for effectively preventing electrical contact between the positive and negative electrodes.

[0004] Therefore, there is a need for a method to provide a cylindrical battery cell with low internal resistance and low short-circuit risk, as well as a battery pack and vehicle including the cylindrical battery cell. Summary of the Invention

[0005] Technical issues

[0006] This disclosure is designed to address the problems of the prior art and is therefore intended to reduce the internal resistance of cylindrical secondary batteries while effectively preventing internal short circuits.

[0007] The technical problems to be solved by this disclosure are not limited to those described above. Other problems not mentioned can be clearly understood by those skilled in the art from the following description of this disclosure.

[0008] Technical solution

[0009] In one aspect of this disclosure, an electrode assembly is provided that is a core-type structure in which a first electrode and a second electrode, both having sheet shapes, and a diaphragm inserted between the first electrode and the second electrode are wound in one direction, wherein each of the first electrode and the second electrode includes: an uncoated portion formed on a longer edge end without being coated with an active material layer; and a coated portion coated with an active material layer and formed on a region other than the uncoated portion.

[0010] The first electrode includes at least one insulating layer that simultaneously covers at least a portion of the uncoated portion and at least a portion of the coated portion.

[0011] Preferably, the insulating layer may be present on both surfaces of the first electrode.

[0012] The uncoated portion of the first electrode may have a structure in which at least a portion of the uncoated portion is bent along the radial direction of the electrode assembly, and the insulating layer may be disposed only on the surface of the first electrode facing the bending direction.

[0013] One end of the insulating layer in the winding axis direction may be located at the same height as one end of the diaphragm in the winding axis direction or outside that end of the diaphragm in the winding axis direction.

[0014] More preferably, one end of the insulating layer in the winding axis direction may be located at the same height as one end of the diaphragm in the winding axis direction.

[0015] According to one embodiment, the uncoated portion may protrude further outward than the insulating layer.

[0016] Preferably, the coated portion may not protrude further than the diaphragm in the direction of the winding axis.

[0017] In one aspect, the first electrode may be a positive electrode.

[0018] According to one embodiment, when the diaphragm is between the second electrode and the insulating layer, the end of the second electrode facing the insulating layer may not protrude further outward than the end of the diaphragm facing the insulating layer.

[0019] The coating portion may include a sliding portion, wherein the active material layer of the sliding portion has a reduced thickness compared to the central region of the coating portion.

[0020] The sliding portion may be formed on the boundary region between the coated portion and the uncoated portion.

[0021] The sliding portion may be included at one end of the first electrode in the winding axis direction and at the other end of the second electrode in the winding axis direction.

[0022] Preferably, the sliding portion of the coated portion included in the first electrode and the sliding portion of the coated portion included in the second electrode can be contained in opposite directions.

[0023] The diaphragm may protrude further outward than the other end of the first electrode in the direction of the winding axis and the end of the second electrode in the direction of the winding axis.

[0024] According to one embodiment, the insulating layer may cover at least a portion of the sliding portion.

[0025] In one aspect, the insulating layer may cover the uncoated portion by 0.3 mm to 5 mm.

[0026] In another embodiment, the insulating layer may cover the uncoated portion by 1.5 mm to 3 mm.

[0027] In another embodiment, the insulating layer may cover the coated portion by 0.1 mm to 3 mm.

[0028] In another embodiment, the insulating layer may cover the coated portion by 0.2 mm to 0.5 mm.

[0029] According to another embodiment, at least a portion of the uncoated portion may be divided into multiple segments.

[0030] Preferably, the plurality of segments can be bent in the radial direction of the electrode assembly.

[0031] In one aspect, the insulating layer may extend to the end of the uncoated portion on one of the two surfaces of the uncoated portion toward the bending direction.

[0032] In one aspect, the insulating layer may surround the end of the uncoated portion.

[0033] In another embodiment, the insulating layer may extend on one of the two surfaces of the uncoated portion, opposite the surface facing the bending direction, up to the bending point of the uncoated portion.

[0034] The segment may be provided only in a portion of a surface of the electrode assembly in the height direction.

[0035] The area of ​​the region where the segment is formed on a surface of the electrode assembly in the height direction can be larger than the area of ​​the region where the segment is not formed.

[0036] Multiple segments adjacent to each other in the radial direction of the electrode assembly may overlap each other in the radial direction of the electrode assembly.

[0037] An insulating layer disposed on one of the two surfaces of the uncoated portion in the bending direction of the uncoated portion may have a shape extending to the end of the uncoated portion in the region forming the segment, and a shape not extending to the end of the uncoated portion in the region not forming the segment.

[0038] According to one embodiment, the uncoated portion included in the first electrode and the uncoated portion included in the second electrode may protrude in opposite directions to each other.

[0039] Preferably, the length of the coated portion in the first electrode in the winding axis direction may be less than the length of the coated portion in the second electrode in the winding axis direction.

[0040] Preferably, the coated portion included in the first electrode may be located further inside in the winding axis direction than the coated portion included in the second electrode.

[0041] In one aspect, the insulating layer may be an insulating coating or insulating tape included on the boundary region between the uncoated portion and the coated portion.

[0042] Preferably, the insulating layer may comprise an oil-based SBR adhesive and aluminum oxide.

[0043] In one aspect of this disclosure, a cylindrical secondary battery is provided, comprising: the electrode assembly described above; a battery can housing the electrode assembly and electrically connected to one of the first electrode and the second electrode; a sealing body sealing the open end of the battery can; and a terminal electrically connected to the other of the first electrode and the second electrode and having a surface exposed to the outside.

[0044] Preferably, the cylindrical secondary battery may further include a first current collector electrically connected to the uncoated portion contained in the first electrode.

[0045] Preferably, the uncoated portion of the first electrode can be electrically connected to the first current collector in the region of the uncoated portion that is not covered by the insulating layer throughout its entire area.

[0046] Preferably, the uncoated portion of the first electrode can be connected to the first current collector by soldering in the area of ​​the uncoated portion that is not covered by the insulating layer throughout its entire area.

[0047] In one aspect of this disclosure, a battery pack is provided, comprising: a cylindrical secondary battery as described above according to this disclosure; and a battery pack housing for accommodating a plurality of cylindrical secondary batteries.

[0048] In one aspect of this disclosure, a vehicle is provided that includes a battery pack as described above according to this disclosure.

[0049] Beneficial effects

[0050] According to this disclosure, the internal resistance of cylindrical secondary batteries can be significantly reduced.

[0051] Furthermore, according to this disclosure, short circuits within a cylindrical secondary battery can be effectively prevented by preventing electrical contact between the positive and negative electrodes of the electrode assembly.

[0052] The effects of this disclosure 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. Attached Figure Description

[0053] The accompanying drawings illustrate preferred embodiments of the present disclosure and are used together with the following disclosure to provide a further understanding of the technical aspects of the present disclosure; therefore, the present disclosure is not to be construed as limited to the drawings.

[0054] Figure 1 This is a perspective view used to explain the cylindrical secondary battery according to embodiments of the present disclosure.

[0055] Figure 2 yes Figure 1 A longitudinal cross-sectional view of a cylindrical secondary battery.

[0056] Figure 3 It is used to explain including Figure 1 A diagram of the electrode assembly in a cylindrical secondary battery.

[0057] Figure 4 yes Figure 3 A portion of the longitudinal cross-sectional view of the electrode assembly.

[0058] Figure 5 This is a perspective view used to explain an electrode assembly according to another embodiment of the present disclosure.

[0059] Figure 6 yes Figure 5 A partial longitudinal cross-sectional view of the electrode assembly.

[0060] Figure 7 and Figure 8 It is used for explanation Figure 6 A diagram of a variant of the electrode assembly.

[0061] Figure 9 This is a diagram used to explain an electrode assembly according to yet another embodiment of the present disclosure.

[0062] Figure 10 and Figure 11 It is used for explanation Figure 9 A diagram of a portion of the longitudinal cross-section of the electrode assembly.

[0063] Figure 12 This is a diagram used to explain the electrode assembly according to the comparative example.

[0064] Figure 13 It is a graph used to illustrate the power distribution under several short-circuit conditions in a secondary battery.

[0065] Figure 14 It is used to illustrate including Figure 1 A three-dimensional view of a cylindrical secondary battery pack.

[0066] Figure 15 It is used to explain including Figure 11 A 3D view of the vehicle with its battery pack.

[0067] Explanation of reference numerals in the attached figures

[0068] 5: Vehicles

[0069] 3: Battery pack

[0070] 2: Battery pack casing

[0071] 1: Cylindrical secondary battery

[0072] 10: Electrode assembly

[0073] C: Winding center

[0074] 11: First electrode

[0075] 11a: Uncoated area

[0076] 11b: Coated portion

[0077] 12: Second electrode

[0078] 12a: Uncoated area

[0079] 12b: Coated portion

[0080] 13: Diaphragm

[0081] 20: Battery can

[0082] 21: Curled edge section

[0083] 22: Crimping section

[0084] 30: Sealing body

[0085] 40: Terminal

[0086] 50: First collector board

[0087] 60: Insulator

[0088] 70: Insulating gasket

[0089] 80: Second collector board

[0090] 90: Sealing gasket Detailed Implementation

[0091] Embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their typical or dictionary meanings, but rather as having meanings and concepts consistent with the technical aspects of this invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their own invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely preferred embodiments of this disclosure and do not represent all technical aspects of this disclosure. It should be understood that various equivalents and modifications of the configurations are possible when this application is filed.

[0092] Reference Figures 1 to 3 According to an embodiment of the present disclosure, the cylindrical secondary battery 1 includes an electrode assembly 10, a battery canister 20, a sealing body 30, and terminals 40.

[0093] In addition to the components mentioned above, the cylindrical secondary battery 1 may also include a first current collector 50 and / or an insulator 60 and / or an insulating gasket 70 and / or a second current collector 80 and / or a sealing gasket 90.

[0094] Reference Figures 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 diaphragm 13 disposed 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.

[0095] The first electrode 11 is either a positive or negative electrode, and the second electrode 12 corresponds to an electrode having the opposite polarity to the first electrode 11. Each of the first electrode 11 and the second electrode 12 may have a sheet shape. The electrode assembly 10 may have, for example, a core-type shape. In other words, the electrode assembly 10 can be manufactured by winding relative to a winding center C a stack formed by sequentially stacking the first electrode 11, the separator 13, the second electrode 12, and the separator 13 at least once. Alternatively, an additional separator 13 may be provided on the outer peripheral surface of the electrode assembly 10 to achieve insulation from the battery canister 20. The electrode assembly 10 may have any core-wound structure known in the art without limitation.

[0096] The first electrode 11 and the second electrode 12 may each include uncoated portions 11a and 12a at their respective longer edge ends, each uncoated portion being uncoated with an active material layer. The first electrode 11 and the second electrode 12 may each include coated portions 11b and 12b in the regions of the first electrode 11 and the second electrode 12 excluding the uncoated portions 11a and 12a, each coated portion being coated with an active material layer.

[0097] In detail, the first electrode 11 includes a first electrode current collector and a first electrode active material coated on one or both surfaces of the first electrode current collector. The area on the first electrode current collector coated with the first electrode active material refers to the coated portion 11b included in the first electrode 11. The uncoated portion 11a, which is not coated with the first electrode active material, may exist at one end of the first electrode current collector in the width direction (parallel to the Z-axis). At least a portion of the uncoated portion 11a can itself serve as an electrode connector. In other words, at least a portion of the uncoated portion 11a can serve as a first electrode connector provided to the first electrode 11. The uncoated portion 11a included in the first electrode 11 may be disposed on the upper part of the electrode assembly 10 housed in the battery canister 20 in the height direction (parallel to the Z-axis).

[0098] The second electrode 12 includes a second electrode current collector and a second electrode active material coated on one or both surfaces of the second electrode current collector. The region on the second electrode current collector coated with the second electrode active material refers to the coated portion 12b included in the second electrode 12. An uncoated portion 12a, not coated with the second electrode active material, may exist at the other end of the second electrode current collector in the width direction (parallel to the Z-axis). At least a portion of the uncoated portion 12a can itself serve as an electrode connector. In other words, at least a portion of the uncoated portion 12a can serve as an electrode connector provided to the second electrode 12. The uncoated portion 12a included in the second electrode 12 may be positioned along the height direction (parallel to the Z-axis) at the lower part of the electrode assembly 10 housed in the battery canister 20.

[0099] The uncoated portion 11a included in the first electrode 11 and the uncoated portion 12a included in the second electrode 12 may protrude in opposite directions. For example, refer to Figure 3 and Figure 4The uncoated portion 11a in the first electrode 11 can protrude upward in the height direction (parallel to the Z-axis) of the electrode assembly 10, and in this case, the uncoated portion 12a in the second electrode 12 can protrude downward in the height direction (parallel to the Z-axis). Therefore, the uncoated portion 11a in the first electrode 11 and the uncoated portion 12a in the second electrode 12 can extend and protrude in opposite directions in the winding axis direction of the electrode assembly 10, i.e., the height direction (parallel to the Z-axis) of the cylindrical secondary battery 1.

[0100] Coated portions 11b and 12b may each include a sliding portion, the active material layer of which has a reduced thickness compared to the central region of coated portions 11b and 12b. For example, see reference. Figure 4 Each of the first electrode 11 and the second electrode 12 may include a sliding portion at one or the other end, wherein the active material layer of the sliding portion has a reduced thickness.

[0101] When electrode active material is applied to an electrode current collector, a sliding portion can form due to a sliding phenomenon occurring near the boundary between the coated and uncoated portions. This sliding phenomenon refers to a situation where, due to the spreading of the slurry containing the electrode active material, less electrode active material is coated at the boundary of the slurry coating area than in the area outside the coating area, resulting in an approximately sloping shape of the slurry at the coating boundary. Because of this sliding phenomenon, a sliding portion with a shape that slopes approximately downwards along the direction from the coated portion towards the uncoated portion can be formed at the edge of the coated portion. Thus, the sliding phenomenon occurring during the coating of the active material can be further enhanced during the drying process of the active material. That is, when the electrode with the sliding portion is completely dry, as the solvent contained in the slurry evaporates, the volume of the slurry decreases, and the sliding phenomenon may become more severe near the boundary between the area coated with electrode active material and the area uncoated with electrode active material.

[0102] Sliding portions may be formed at the boundary regions between the coated portions 11b and 12b and the uncoated portions 11a and 12a. For example, sliding portions may be included at one end of the first electrode 11 and the other end of the second electrode 12, respectively. In other words, the sliding portions of the coated portions 11b included in the first electrode 11 and the sliding portions of the coated portions 12b included in the second electrode 12 may be included in opposite directions to each other. For example, refer to... Figure 4 The sliding portion of the first electrode 11 can be formed in the upper part of the winding axis direction (parallel to the Z-axis), and the sliding portion of the second electrode 12 can be formed in the opposite direction to the sliding portion of the first electrode 11, that is, in the lower part of the winding axis direction (parallel to the Z-axis).

[0103] The length of the coating portion 11b included in the first electrode 11 in the winding axis direction (parallel to the Z-axis) can be less than the length of the coating portion 12b included in the second electrode 12 in the winding axis direction (parallel to the Z-axis). The coating portion 11b included in the first electrode 11 can be positioned more inwardly in the winding axis direction (parallel to the Z-axis) than the coating portion 12b included in the second electrode 12. For example, referring to... Figure 4 The length of the coating portion 12b included in the second electrode 12 in the winding axis direction (parallel to the Z-axis) can be greater than the length of the coating portion 11b included in the first electrode 11 in the winding axis direction (parallel to the Z-axis). (Refer to...) Figure 4 The length of the coating portion 11b in the first electrode 11 along the winding axis (parallel to the Z-axis) can also be less than the length of the coating portion 12b in the second electrode 12 along the winding axis (parallel to the Z-axis). This structure is provided to prevent lithium metal from depositing due to the NP ratio of the positive electrode / negative electrode decreasing to below 100%.

[0104] The coated portions 11b and 12b do not protrude further than the diaphragm 13 in the direction of the winding axis (parallel to the Z-axis). If the coated portions 11b and 12b protrude further than the diaphragm 13 in the direction of the winding axis (parallel to the Z-axis), the possibility of contact between the first electrode 11 and the second electrode 12 may increase. Therefore, an internal short circuit may occur in the contact area between the first electrode 11 and the second electrode 12, increasing the risk of ignition. Therefore, it is important that the coated portions 11b and 12b do not protrude further than the diaphragm 13 in the direction of the winding axis (parallel to the Z-axis). In other words, it is preferable that the coated portions 11b and 12b are positioned inward from both ends of the diaphragm 13.

[0105] In this disclosure, positive electrode active materials coated on the positive electrode plate and negative electrode active materials coated on the negative electrode plate can be used without limitation, as long as they are active materials known in the art.

[0106] In one instance, the positive electrode active material may include materials of the general formula A[A x M y O 2+z (Where A includes at least one element selected from Li, Na and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, 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 chosen such that the compound remains electrically neutral.)

[0107] In another example, the positive electrode active material may be an alkali metal compound xLiM 1 O2-(1-x)Li2M 2 O3, where M 1 comprises at least one element with an average oxidation state of 3; M 2 comprises at least one element with an average oxidation state of 4; 0 ≤ x ≤ 1.

[0108] In another example, the positive electrode active material may be a lithium metal phosphate represented by the general formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (where M 1 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 comprises halogen elements that selectively include F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected such that the compound remains electrically neutral), or Li3M2(PO4)3 [where M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].

[0109] Preferably, the positive electrode active material may include primary particles and / or secondary particles in which the primary particles are aggregated.

[0110] In one example, as the negative electrode active material, carbon materials, lithium metal or lithium metal compounds, silicon or silicon compounds, tin or tin compounds can be used. Metal oxides with a potential less than 2V such as TiO2 or SnO2 can also be used as the negative electrode active material. As the carbon material, low-crystalline carbon, high-crystalline carbon, etc. can be used.

[0111] As a separator, porous polymer membranes (e.g., porous polymer membranes made from polyolefin polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, or ethylene / methacrylate copolymers) can be used alone or by stacking them. As another example, as a separator, typical porous nonwoven fabrics can be used, such as nonwoven fabrics formed from glass fibers or polyethylene terephthalate fibers with high melting points.

[0112] The inorganic particle coating may be contained on at least one surface of the diaphragm. The diaphragm itself may be formed from the inorganic particle coating. The particles constituting the coating may have a structure bonded to a binder, such that there are interstitial volumes between adjacent particles.

[0113] Inorganic particles can be formed from inorganic materials with a dielectric constant of 5 or greater. As a non-limiting example, inorganic particles may include materials selected from Pb(Zr,Ti)O3 (PZT), Pb... 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb) 2 / 3 At least one material from the group consisting of O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0114] Electrolytes can be those with properties such as A + B - Salts of the structure. Here, A + Including alkali metal cations such as Li + Na + and K + , or ions corresponding to its combination. B - Including those selected from 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 - .

[0115] Electrolytes can also be used after being dissolved in an organic solvent. Suitable organic solvents include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or mixtures thereof.

[0116] To minimize the possibility of contact between the first electrode 11 and the second electrode 12, the first electrode 11 according to this disclosure may include at least one insulating layer 14 that simultaneously covers at least a portion of the uncoated portion and at least a portion of the coated portion. The insulating layer 14 can effectively prevent electrical contact between the first electrode 11 and the second electrode 12. More specifically, the insulating layer 14 can effectively prevent electrical contact between the uncoated portion 11a included in the first electrode 11 and the coated portion 12b included in the second electrode 12.

[0117] The insulating layer 14 may be formed on at least one surface of the first electrode 11. For example, the insulating layer 14 may be formed on both surfaces of the first electrode 11. Although not on Figure 4 As shown, however, the diaphragm 13 is located on the left and right sides of the first electrode 11, and another second electrode 12 is located to the left of the left side of the diaphragm 13. Therefore, in order to prevent electrical contact with the second electrodes 12 located on the left and right sides of the insulating layer 14, the insulating layer 14 can be formed on both surfaces of the first electrode 11 respectively.

[0118] The insulating layer 14 can be formed over the entire area of ​​the first electrode 11 that may face the coating portion 12b included in the second electrode 12. For example, one end of the insulating layer 14 in the winding axis direction (parallel to the Z-axis) may be located at the same height as one end of the diaphragm 13 in the winding axis direction (parallel to the Z-axis), or it may be located outside that end. More detailed description by way of example follows. Figure 4 One end of the insulating layer 14 in the winding axis direction (parallel to the Z-axis) can be located at the same height as one end of the separator 13 in the winding axis direction. Because the separator 13 can protrude between the first electrode 11 and the second electrode 12 in the winding axis direction (parallel to the Z-axis) to the same height as or higher than the end of the second electrode 12, electrical contact between the first electrode 11 and the second electrode 12 can be prevented to some extent. However, because movement (e.g., serpentine movement) of the first electrode 11 or the second electrode 12 can occur within the cylindrical secondary battery 1, the possibility that the second electrode 12 may be located near the end of the separator 13 cannot be ruled out. Therefore, when the second electrode 12 is located at the end of the separator 13 or when the second electrode 12 protrudes further outward than the end of the separator 13 due to movement such as serpentine movement, electrical contact between the first electrode 11 and the second electrode 12 may not be avoided. Alternatively, when the separator 13 is damaged for some reason, electrical contact between the first electrode 11 and the second electrode 12 may not be avoided. In particular, the possibility of ignition is very high when an internal short circuit occurs due to contact between the uncoated portion 11a of the first electrode 11 and the coated portion 12b of the second electrode 12. Therefore, in order to prevent electrical contact between the first electrode 11 and the second electrode 12, preferably, the insulating layer 14 included in the first electrode 11 extends at least to the same height as one end of the diaphragm 13, or extends outward from that end.

[0119] However, when the insulating layer 14 covers the entire uncoated portion 11a included in the first electrode 11, the first electrode 11 cannot be used as an electrode. Therefore, the insulating layer 14 only needs to cover a portion of the uncoated portion 11a included in the first electrode 11. In other words, the uncoated portion 11a can have a shape that protrudes further outward from the insulating layer 14.

[0120] The insulating layer 14 may be an insulating coating or insulating tape included in the boundary region between the uncoated portion 11a and the coated portion 11b. The shape of the insulating layer 14 is not limited thereto, and any shape capable of attaching the insulating layer 14 to the first electrode 11 while ensuring insulation performance may be adopted in this disclosure. The insulating layer 14 may include, for example, an oil-based SBR adhesive and alumina to ensure insulation performance.

[0121] The insulating layer 14 may simultaneously cover at least a portion of the uncoated portion 11a and at least a portion of the coated portion 11b. For example, the insulating layer 14 may be formed on the boundary region between the uncoated portion 11a and the coated portion 11b. For example, the insulating layer 14 may cover at least a portion of the sliding portion.

[0122] For example, the insulating layer 14 may extend over the entire area of ​​the uncoated portion 11a included in the first electrode 11 to a point approximately 0.3 mm to approximately 5 mm from the boundary between the uncoated portion 11a and the coated portion 11b. More preferably, the insulating layer 14 may extend over the entire area of ​​the uncoated portion 11a included in the first electrode 11 to a point approximately 1.5 mm to approximately 3 mm from the boundary between the uncoated portion 11a and the coated portion 11b.

[0123] When the insulating layer 14 is not present, an internal short circuit may occur between the first electrode 11 and the second electrode 12 due to the possibility of contact between them. Therefore, it is preferable that the insulating layer 14 extends to a position where there is no electrical contact between the first electrode 11 and the second electrode 12.

[0124] The insulating layer 14 may extend over the entire area of ​​the coated portion 11b included in the first electrode 11 to a point approximately 0.1 mm to approximately 3 mm away from the boundary between the uncoated portion 11a and the coated portion 11b. More preferably, the insulating layer 14 may extend over the entire area of ​​the coated portion 11b included in the first electrode 11 to a point approximately 0.2 mm to approximately 0.5 mm away from the boundary between the uncoated portion 11a and the coated portion 11b.

[0125] When the insulating layer 14 covers a portion of the coating portion 11b included in the first electrode 11, capacity loss occurs in the cylindrical secondary battery 1, therefore it is necessary to minimize the length of the coating portion covering the insulating layer 14. However, since the coating portion 11b included in the first electrode 11 may contact the second electrode 12, the insulating layer 14 needs to cover at least a portion of the coating portion 11b included in the first electrode 11 to prevent contact.

[0126] Reference Figure 4 The diaphragm 13 may have a shape that protrudes outward from one end of the first electrode 11 and one end of the second electrode 12. For ease of explanation, Figure 4 One end refers to the end in the upper direction (parallel to the Z-axis) of the winding axis direction, while Figure 4The other end refers to the end in the lower direction (parallel to the Z-axis) of the winding axis direction. Therefore, the diaphragm 13 can have a shape that protrudes further outward from the lower end of the first electrode 11 and further outward from the upper end of the second electrode 12. The diaphragm 13 does not protrude from the upper end of the first electrode 11 so that the upper end of the first electrode 11, i.e., the uncoated portion 11a, itself serves as the electrode connector for the first electrode 11. Similarly, the diaphragm 13 does not protrude from the lower end of the second electrode 12 so that the lower end of the second electrode 12, i.e., the uncoated portion 12a, itself serves as the electrode connector provided to the second electrode 12. In this disclosure, the uncoated portions 11a and 12a serving as electrode connectors means that the uncoated portions 11a and 12a correspond to connection terminals for electrically connecting other components such as the first current collector 50 and the second current collector 80, the battery canister 20, and the terminals 40 to the electrode assembly 10.

[0127] The end of the second electrode 12 facing the insulating layer 14, separated by the diaphragm 13, may not protrude further outward than the end of the diaphragm 13. For example, refer to... Figure 4 An insulating layer 14 is included on one end of the first electrode 11, and the end of the second electrode 12 facing the insulating layer 14 is located inside the diaphragm 13. Therefore, even when one end of the first electrode 11 protrudes outward from the diaphragm 13, the possibility of contact between the first electrode 11 and the second electrode 12 is significantly reduced because one end of the second electrode 12 is located inside the diaphragm 13. Specifically, in this region, when the coated portion 12b formed at one end of the second electrode 12 is exposed to the outside of the diaphragm 13, the uncoated portion 11a formed at one end of the first electrode 11 and the coated portion 12b formed at one end of the second electrode 12 can contact each other. As described above, when the uncoated portion 11a of the first electrode 11 and the coated portion 12b of the second electrode 12 are in contact with each other, the risk of ignition is very high, therefore, as described above, it is even more necessary to configure the second electrode 12 so as not to be exposed to the outside of the diaphragm 13.

[0128] Meanwhile, the uncoated portion 12a of the second electrode 12 can be exposed to the outside of the diaphragm 13, allowing other components to be easily connected to the uncoated portion 12a located at the other end of the second electrode 12. In this case, the other end of the first electrode 11 can be located inside the diaphragm 13 to prevent contact between the coated portion 11b located at the other end of the first electrode 11 and the uncoated portion 12a located at the other end of the second electrode 12. However, in the lower part of the electrode assembly 10 of this disclosure, unlike the upper part, the insulating layer 14 may not be applied to the second electrode 12.

[0129] Specifically, when the first electrode 11 is the positive electrode and the second electrode 12 is the negative electrode, considering process efficiency, productivity, and the risk of short circuits, the insulating layer 14 may be formed on the uncoated portion 11a of the first electrode 11, and the insulating layer 14 may not be applied to the uncoated portion 12a of the second electrode 12. This is because, in particular, the greatest risk occurs when the uncoated portion of the positive electrode and the coated portion of the negative electrode come into contact with each other. Reference will be made below. Figure 10 The risk differences under various conditions where the positive and negative electrodes are in contact with each other are described in detail. On the other hand, this disclosure does not exclude the possibility that the insulating layer 14 is disposed on the uncoated portion 12a of the second electrode 12.

[0130] refer to Figure 1 and Figure 2 The battery can 20 is a generally cylindrical container with an opening at its lower end, and is formed, for example, of a conductive material such as metal. The material of the battery can 20 can be, for example, aluminum, steel, stainless steel, etc. The bottom of the battery can 20, including the opening, is referred to as the open end. The sides (outer peripheral surfaces) and the top surface of the battery can 20 can be integrally formed. The top surface of the battery can 20 (the surface parallel to the XY plane) is generally flat. The top surface of the battery can 20 opposite to the open end is referred to as the closed end. The battery can 20 accommodates the electrode assembly 10 through the opening formed at its lower part, and also accommodates the electrolyte.

[0131] The battery can 20 is electrically connected to the electrode assembly 10. The battery can 20 may be electrically connected to one of the first electrode 11 and the second electrode 12. For example, the battery can 20 may be electrically connected to the second electrode 12 of the electrode assembly 10. In this case, the battery can 20 may have the same polarity as the second electrode 12.

[0132] Reference Figure 2 The battery can 20 may include a rolled edge portion 21 and a crimped portion 22 formed at its lower end. The rolled edge portion 21 is located below the electrode assembly 10. The rolled edge portion 21 is formed by crimping the circumference of the outer circumferential surface of the battery can 20. The rolled edge portion 21 prevents the electrode assembly 10, which may have a size that substantially corresponds to the inner diameter of the battery can 20, from escaping through the opening formed at the lower end of the battery can 20, and can also serve as a support portion on which the sealing body 30 is mounted.

[0133] A crimping portion 22 is formed below the rolled edge portion 21. The crimping portion 22 has an extended and curved shape to surround a portion of the outer circumferential surface of the sealing body 30 disposed below the rolled edge portion 21 and the lower surface of the sealing body 30.

[0134] However, this disclosure does not preclude the possibility that the battery can 20 does not include the aforementioned rolled edge portion 21 and / or crimped portion 22. In other words, in this disclosure, when the battery can 20 does not include the rolled edge portion 21 and / or crimped portion 22, the electrode assembly 10 can be fixed and / or the battery can 20 can be sealed, for example, by further applying components that can serve as stop members relative to the electrode assembly 10. When the cylindrical secondary battery 1 according to an embodiment of this disclosure includes a sealing body 30, the electrode assembly 10 can be fixed and / or the battery can 20 can be sealed, for example, by further applying a structure on which the sealing body 30 can be located and / or by performing welding between the battery can 20 and the sealing body 30, such that the sealing body 30 can seal the open end of the battery can 20.

[0135] Reference Figure 2 The sealing body 30 may be formed of, for example, a metallic material to ensure rigidity. The sealing body 30 may cover the opening formed at the lower end of the battery canister 20. In other words, the sealing body 30 forms the lower surface of the cylindrical secondary battery 1. In the cylindrical secondary battery 1 according to the embodiments of this disclosure, even when the sealing body 30 comprises a conductive metallic material, the sealing body 30 may not be polarized. When the sealing body 30 is not polarized, this may mean that the sealing body 30 is electrically insulated from the battery canister 20 and the terminal 40. Therefore, the sealing body 30 is not used as the positive terminal 40 or the negative terminal 40. Therefore, the sealing body 30 does not need to be electrically connected to the electrode assembly 10 and the battery canister 20, and its material does not necessarily have to be a conductive metal.

[0136] When the battery can 20 according to this disclosure includes a rolled edge portion 21, the sealing body 30 may be disposed on the rolled edge portion 21 formed in the battery can 20. When the battery can 20 according to this disclosure includes a crimp portion 22, the sealing body 30 is fixed by the crimp portion 22. A sealing gasket 90 may be disposed between the sealing body 30 and the crimp portion 22 of the battery can 20 to ensure the airtightness of the battery can 20. As described above, the battery can 20 according to this disclosure may not include the rolled edge portion 21 and / or the crimp portion 22. In this case, to ensure the airtightness of the battery can 20, the sealing gasket 90 may be disposed between the sealing body 30 and the fixing structure (crimp portion 22) disposed at the opening of the battery can 20.

[0137] refer to Figure 1 and Figure 2 Terminal 40 can be electrically connected to one of the first electrode 11 and the second electrode 12. In other words, terminal 40 can have the opposite polarity to the battery canister 20. For example, terminal 40 can be electrically connected to the first electrode 11 of the electrode assembly 10. The surface of terminal 40 can be exposed to the outside.

[0138] Terminal 40 may be formed of a conductive metallic material. Terminal 40 may pass through, for example, the generally central portion of the closed end of battery can 20. A portion of terminal 40 may be exposed on the upper side of battery can 20, while the remainder may be located inside battery can 20. Terminal 40 may be fixed to the inner surface of the closed end of battery can 20, for example, by riveting. Terminal 40 may pass through insulator 60 and be connected to the first current collector 50 or the uncoated portion 11a included in the first electrode 11. In this case, terminal 40 may have a first polarity. Thus, terminal 40 may be used as the first electrode terminal of the cylindrical secondary battery 1 according to an embodiment of the present disclosure. When terminal 40 has the first polarity as described above, terminal 40 is electrically insulated from battery can 20 having a second polarity. Electrical insulation between terminal 40 and battery can 20 may be achieved in various ways. For example, insulation may be achieved by providing an insulating gasket 70, which will be described later, between terminal 40 and battery can 20. Alternatively, insulation may be achieved by forming an insulating coating on a portion of terminal 40. Alternatively, a method can be used to structurally securely fix the terminal 40 to prevent contact between the terminal 40 and the battery canister 20. Alternatively, multiple methods described above can be used together.

[0139] Reference Figure 2 The first current collector 50 can be connected to the upper part of the electrode assembly 10. For example, the first current collector 50 above the electrode assembly 10 can be coupled to the uncoated portion 11a included in the first electrode 11. The first current collector 50 can be formed of a conductive metallic material. Although not shown in the figures, the first current collector 50 may include a plurality of protrusions radially formed on its lower surface. When including a plurality of irregular portions, pressing the first current collector 50 allows the plurality of protrusions to press-fit onto the uncoated portion 11a included in the first electrode 11.

[0140] According to another embodiment of this disclosure, the cylindrical secondary battery 1 may not include the first current collector 50. In this case, the uncoated portion 11a included in the first electrode 11 can be directly electrically connected to the terminal 40.

[0141] Reference Figure 2The first current collector 50 can be coupled to the end of the uncoated portion 11a included in the first electrode 11. The connection between the uncoated portion 11a included in the first electrode 11 and the first current collector 50 can be achieved, for example, by laser welding. Laser welding can be performed by partially melting the bottom member of the first current collector 50, or alternatively, by using solder for welding inserted between the first current collector 50 and the uncoated portion 11a. In this case, preferably, the solder has a lower melting point than the first current collector 50 and the uncoated portion 11a. In addition to laser welding, resistance welding, ultrasonic welding, spot welding, etc., can also be used, but the welding method is not limited to these.

[0142] Reference Figure 5 The first current collector 50 can be coupled to a coupling surface formed by bending the end of the uncoated portion 11a included in the first electrode 11 along a direction parallel to the first current collector 50. The bending direction of the uncoated portion 11a can be, for example, toward the winding center C of the electrode assembly 10 (see...). Figure 2 The direction of the uncoated portion 11a is as described above. When the uncoated portion 11a has a curved shape, the space occupied by the uncoated portion 11a can be reduced, thereby increasing the energy density. In addition, due to the increase in the connection area between the uncoated portion 11a and the first current collector 50, the connection force can be improved and the resistance can also be reduced.

[0143] Reference Figure 2 An insulator 60 may be disposed between the upper end of the electrode assembly 10 and the inner surface of the battery can 20, or between the first current collector 50 and the inner surface of the battery can 20. The insulator 60 prevents contact between the uncoated portion 11a included in the first electrode 11 and the battery can 20, and / or between the first current collector 50 and the battery can 20. In other words, the insulator 60 is housed within the battery can 20 and configured to block the electrical connection between the uncoated portion 11a included in the first electrode 11 and the battery can 20. Therefore, the insulator 60 may be formed of a material with insulating properties. For example, the insulator 60 may comprise a polymer material.

[0144] Reference Figure 1 and Figure 2 An insulating gasket 70 is disposed between the battery terminal 40 and the battery canister 20 to prevent contact between the battery canister 20 and the terminal 40, which have opposite polarities. In other words, the insulating gasket 70 blocks the electrical connection between the battery canister 20 and the terminal 40. Therefore, the upper surface of the battery canister 20, which has a generally flat shape, can be used as another terminal for electrical connection to the second electrode 12 of the cylindrical secondary battery 1.

[0145] Reference Figure 2The second current collector 80 can be connected to the lower part of the electrode assembly 10. The second current collector 80 can be formed of a conductive metallic material. The second current collector 80 can be connected to the uncoated portion 12a included in the second electrode 12. The second current collector 80 can be electrically connected to the battery canister 20. Figure 2 As shown, at least one circumferential portion of the second current collector 80 can be secured by interlocking between the inner surface (lower surface) of the rolled edge portion 21 of the battery can 20 and the sealing gasket 90. Alternatively, the second current collector 80 can be soldered to the inner surface of the battery can 20, rather than to the inner surface (lower surface) of the rolled edge portion 21 of the battery can 20.

[0146] Although not shown in the accompanying drawings, the second current collector 80 may include a plurality of protrusions radially formed on one of its surfaces. When the plurality of protrusions are included, pressing the second current collector 80 allows the plurality of protrusions to press-fit onto the uncoated portion 12a included in the second electrode 12.

[0147] Reference Figure 2 The second current collector 80 can be connected to the end of the uncoated portion 12a included in the second electrode 12. The connection between the uncoated portion 12a included in the second electrode 12 and the second current collector 80 can be achieved, for example, by laser welding. Laser welding can be performed by partially melting the bottom component of the second current collector 80, or optionally by solder inserted between the second current collector 80 and the uncoated portion 12a. In this case, it is preferable that the solder has a lower melting point than the second current collector 80 and the uncoated portion 12a. In addition to laser welding, resistance welding, ultrasonic welding, spot welding, etc., can also be used, but the welding method is not limited to these.

[0148] Although not shown in the accompanying drawings, the second current collector 80 can be coupled to a coupling surface formed by bending the end of the uncoated portion 12a included in the second electrode 12 in a direction parallel to the second current collector 80. The bending direction of the uncoated portion 12a included in the second electrode 12 can, for example, be towards the winding center C of the electrode assembly 10 (see...). Figure 2 The direction of the uncoated portion 12a included in the second electrode 12 is such that when it has the curved shape described above, the space occupied by the uncoated portion 12a can be reduced, thereby increasing the energy density. Furthermore, due to the increased connection area between the uncoated portion 12a and the second collector plate 80, the connection force can be increased and the resistance can also be reduced.

[0149] Reference Figure 2The gasket 90 may have a generally annular shape surrounding the circumference of the sealing body 30. The gasket 90 may simultaneously cover the lower, upper, and side surfaces of the sealing body 30. The radial length of the portion of the gasket 90 covering the upper surface of the sealing body 30 may be less than or equal to the radial length of the portion of the gasket 90 covering the lower surface of the sealing body 30. When the radial length of a portion of the gasket 90 covering the upper surface of the sealing body 30 is too large, the gasket 90 may compress the second current collector 80 during the sizing process of vertically compressing the battery can 20, potentially damaging the second current collector 80 or the battery can 20. Therefore, the radial length of the portion of the gasket 90 covering the upper surface of the sealing body 30 needs to be kept relatively small at a certain level.

[0150] Because according to Figure 5 The electrode assembly 10 of the embodiment is similar to that according to Figure 3 The electrode assembly 10 of the embodiment, therefore according to Figure 5 The implementation method and the basis Figure 3 The components of the embodiments that are substantially the same or similar will not be repeated here, and the differences between them will be described in detail.

[0151] refer to Figure 5 According to another embodiment of the present disclosure, the electrode assembly 10 may have a structure in which at least a portion of the uncoated portions 11a and 12a are bent in the radial direction of the electrode assembly 10. For example, according to another embodiment of the present disclosure, the electrode assembly 10 may have a structure in which at least a portion of the uncoated portions 11a and 12a are bent toward the core of the electrode assembly 10. For example, referring to... Figure 5 At least a portion of the uncoated portions 11a and 12a can be divided into multiple segments F. The multiple segments F can overlap in multiple layers while bending towards the core. For example, the multiple segments F can be notched by a laser. The segments F can be formed by known metal foil cutting processes, such as ultrasonic cutting or stamping. Multiple segments F adjacent to each other in the radial direction of the electrode assembly 10 can overlap each other as they bend in the radial direction of the electrode assembly 10. The number of overlapping layers of the segments F can vary along the radial direction, and the number of overlapping layers can be maintained in a specific region. The segments F can be formed in the uncoated portion 11a of the first electrode 11 and / or the uncoated portion 12a of the second electrode 12.

[0152] To prevent damage to the active material layer and / or insulating layer 14 during bending of the uncoated portions 11a and 12a, a predetermined gap is preferably provided between the lower end of the cut line of segment F and the active material layer. This is because stress concentrates near the lower end of the cut line when the uncoated portions 11a and 12a are bent. The gap is preferably 0.2 mm to 4 mm. When the gap is controlled within this range, damage to the active material layer and / or insulating layer 14 near the lower end of the cut line can be prevented by stress generated during bending of the uncoated portions 11a and 12a. This gap also prevents damage to the active material layer and / or insulating layer 14 due to tolerances during grooving or cutting of segment F.

[0153] The bending direction of the uncoated portions 11a and 12a can be, for example, towards the winding center C of the electrode assembly 10. When the uncoated portions 11a and 12a have the bending shape described above, the space occupied by the uncoated portions 11a and 12a can be reduced, thereby increasing the energy density. Furthermore, since the connection area between the uncoated portions 11a and 12a and the first current collector 50 and the second current collector 80 is increased, the connection force can be further improved, and the resistance can be further reduced.

[0154] refer to Figure 5 and Figure 6 The uncoated portion 11a in the first electrode 11 can be bent in one direction. For example, in Figure 6 In this configuration, the +X direction can be towards the core. When the uncoated portion 11a bends towards the core as described above, the uncoated portion 11a of the first electrode 11 can approach the second electrode 12 and extend beyond the separator 13. Therefore, the insulating layer 14 can extend from the core-facing surface of one of the two surfaces of the uncoated portion 11a to the end of the uncoated portion 11a included in the first electrode 11. According to this structure, even when the uncoated portion 11a bends towards the core and extends beyond the separator 13 to approach the second electrode 12, electrical contact between the first electrode 11 and the second electrode 12 can be prevented. Therefore, internal short circuits of the cylindrical secondary battery 1 can be effectively prevented.

[0155] At the same time, with Figures 6 to 8 Unlike the example shown, the insulating layer 14 may not extend to the end of the uncoated portion 11a on the surface of the uncoated portion 11a located in the bending direction. That is, at least a portion of the inner surface of the bent uncoated portion 11a may not be covered by the insulating layer 14. This allows when the bent section F (see...) Figure 5 When the electrode assemblies 10 overlap each other radially, the overlapping sections F can be electrically connected to each other.

[0156] Meanwhile, when the uncoated portion 11a of the first electrode 11 has a shape that bends in one direction, the insulating layer 14 can be disposed only on one of the two surfaces of the uncoated portion 11a positioned along the bending direction. For example, when the uncoated portion 11a bends in a direction toward the winding center C, the insulating layer 14 can be disposed only on the surface of the uncoated portion 11a facing the winding center C. This is because when the uncoated portion 11a of the first electrode 11 bends in one direction, the probability of contact with the second electrode 12 located in the bending direction is greater than the probability of contact with the second electrode 12 located in the opposite direction.

[0157] According to another embodiment of this disclosure, when the uncoated portion 11a of the first electrode 11 has a shape that is bent in one direction and the insulating layer 14 is disposed on both surfaces of the uncoated portion 11a of the first electrode 11, the insulating layer 14 disposed in the bending direction can have a greater thickness than the insulating layer 14 disposed on the opposite side. In this case, the reduction in stiffness that may occur in the bent portion corresponding to the thin metal foil can be compensated.

[0158] Reference Figure 6 The insulating layer 14 may be included only on a portion of the surface of the uncoated portion 11a opposite the surface facing the core. In other words, the upper portion of the surface of the uncoated portion 11a opposite the surface facing the core may be exposed to the outside. Therefore, through the exposed area of ​​the surface of the uncoated portion 11a opposite the surface facing the core, the uncoated portion 11a may make electrical contact with another uncoated portion 11a or the first current collector 50 included in the adjacent first electrode 11 (not shown) on the left. Preferably, the uncoated portion 11a may be electrically connected to the first current collector 50 in the area of ​​the uncoated portion 11a not covered by the insulating layer 14, and bend toward the core of the electrode assembly 10. Furthermore, the uncoated portion 11a may be connected to the first current collector 50 in the entire area of ​​the uncoated portion 11a by welding in the area of ​​the uncoated portion 11a not covered by the insulating layer 14. Welding may be, for example, laser welding. Laser welding can be performed by partially melting the bottom component of the first current collector 50, or it can be performed using solder inserted between the first current collector 50 and the uncoated portion 11a. In this case, preferably, the solder has a lower melting point than the first current collector 50 and the uncoated portion 11a. In addition to laser welding, resistance welding, ultrasonic welding, spot welding, etc., can also be used, but the welding method is not limited to these.

[0159] Reference Figure 7The insulating layer 14 may have a shape surrounding the end of the uncoated portion 11a. Specifically, the insulating layer 14 may have a shape surrounding the end surface of the uncoated portion 11a. For example, when the length of the bent uncoated portion 11a is large, the likelihood of contact with the second electrode 12 increases. Furthermore, the bent uncoated portion 11a may be further bent due to vibration or external impact. In this case, the likelihood of the end face of the bent uncoated portion 11a contacting the second electrode 12 increases. However, according to this structure of the present disclosure, even when the uncoated portion 11a is further bent or deformed, electrical contact between the first electrode 11 and the second electrode 12 can be prevented because the insulating layer 14 covers the end surface of the uncoated portion 11a.

[0160] Reference Figure 8 The insulating layer 14 may extend to the bend point of the uncoated portion 11a on one of the two surfaces opposite the surface facing the core. Although not shown in the figure, another diaphragm 13 and another second electrode 12 are located at... Figure 8 The first electrode 11 is located to the left of the first electrode. In other words, the first electrode 11 may be in electrical contact not only with the second electrode 12 located to the right of the first electrode 11, but also with the second electrode 12 located to the left of the first electrode 11. However, according to this structure of the present disclosure, electrical contact between the first electrode 11 and the second electrode 12 located on both sides can be reliably prevented.

[0161] On the other hand, refer to Figures 9 to 11 In another embodiment of the electrode assembly 10 according to this disclosure, with Figure 5 Unlike the electrode assembly 10 shown, the segment F may not be disposed over the entire area of ​​a surface of the electrode assembly 10 in the height direction (parallel to the Z-axis), but may only be disposed over a portion of the area. For example, on a surface of the electrode assembly 10 in the height direction, the area A1 where the segment F is located may be larger than the area A2 where the segment F is not formed. Simultaneously, in the area A2 where the segment F is not formed, a portion of the uncoated portion 11a may be cut and removed to have approximately the same height as the area A1 where the segment F is formed. In the following description, the case of forming the segment F in the uncoated portion 11a of the first electrode 11 will be described as an example; however, in this disclosure, the segment F may be formed in the uncoated portion 11a of the first electrode 11 and / or the uncoated portion 12a of the second electrode 12.

[0162] Segment F can be formed discontinuously along the winding direction of the first electrode 11. In this case, a current collector can be connected to the region A1 where segment F is formed. Multiple segments F adjacent to each other in the radial direction of the electrode assembly 10 can overlap in the radial direction of the electrode assembly 10. In this case, the insulating layer 14 disposed on one surface of the uncoated portion 11a in the bending direction of the uncoated portion 11a in one of the two surfaces of the uncoated portion 11a of the first electrode 11 can have a shape that extends to the end of the uncoated portion 11a in the region A1 where segment F is formed, and can have a shape that does not extend to the end in the region A2 where segment F is not formed. For example, the insulating layer 14 has a shape that extends to the end in the region where segment F is formed (see Figure 11 The shape of the bend that extends only to the uncoated portion 11a (see) Figure 11 Alternatively, it may have a shape that extends to cover only a portion of the inner surface of the uncoated portion 11a that bends in the radial direction at the bend point of the electrode assembly 10 (see [reference]). Figure 10 ).

[0163] At the same time, Figures 9 to 11 The diagram shows a structure in which the insulating layer 14 is formed only on one surface of the uncoated portion 11a, but this disclosure is not limited thereto. That is, in Figures 9 to 11 In the embodiment of the electrode assembly 10 shown, as referred to Figures 5 to 8 In the case of the electrode assembly 10, the insulating layer 14 may be formed on one or both surfaces of the uncoated portion 11a.

[0164] Figure 12 This is a cross-sectional view of the electrode assembly 10 excluding the insulating layer 14, based on a comparative example. (Refer to...) Figure 12 No insulating layer 14 is formed on the boundary region between the uncoated portion 11a and the coated portion 11b of the first electrode 11. According to this structure, when movement (e.g., serpentine movement) occurs between the first electrode 11 and the second electrode 12, the second electrode 12 is located at the very end of the diaphragm 13, or the second electrode 12 protrudes further outward than the end of the diaphragm 13, thus allowing electrical contact between the first electrode 11 and the second electrode 12. Alternatively, electrical contact may occur between the first electrode 11 and the second electrode 12 when the diaphragm 13 is damaged for some reason. In this case, in the presence of… Figure 12 In the electrode assembly 10 with its specific structure, the electrical contact between the first electrode 11 and the second electrode 12 can cause an internal short circuit. Therefore, the risk of ignition increases.

[0165] Figure 13 This is a graph illustrating the power distribution under several short-circuit conditions within the cylindrical secondary battery 1. (Reference) Figure 10 It can be assumed that the following four short circuit scenarios may occur in the cylindrical secondary battery 1.

[0166] The following situations exist: situation (i) the coated portion contained in the positive electrode and the coated portion contained in the negative electrode are in electrical contact with each other; situation (ii) the coated portion contained in the positive electrode and the uncoated portion contained in the negative electrode are in electrical contact with each other; situation (iii) the coated portion contained in the negative electrode and the uncoated portion contained in the positive electrode are in electrical contact with each other; and situation (iv) the uncoated portion contained in the positive electrode and the uncoated portion contained in the negative electrode are in electrical contact with each other.

[0167] Reference Figure 13 As can be seen, the highest power is achieved in case (iii) where the coated portion in the negative electrode and the uncoated portion in the positive electrode are in electrical contact with each other. In other words, the probability of ignition is very high in case (iii) where the coated portion in the negative electrode and the uncoated portion in the positive electrode are in electrical contact with each other. This is because the short-circuit current is large due to the very low resistance, resulting in a rapid temperature rise.

[0168] Therefore, considering the structure of the electrode assembly 10 according to this disclosure, there is a need for a structure that can prevent electrical contact between the coated portion contained in the negative electrode and the uncoated portion contained in the positive electrode.

[0169] As a result of in-depth research into these problems, the inventors have discovered that when an insulating layer 14 is provided on at least a portion of the uncoated portion included in the positive electrode, electrical contact with the coated portion included in the negative electrode can be effectively prevented, thus completing this disclosure. In other words, the first electrode 11 can be a positive electrode. However, the first electrode 11 is not limited to a positive electrode and can also be a negative electrode. This disclosure does not exclude the possibility of forming the insulating layer 14 on the second electrode 12. In other words, the insulating layer 14 can be formed on both the positive and negative electrodes. In this case, all possible short-circuit conditions can be prevented.

[0170] Preferably, the cylindrical battery cell can be, for example, a cylindrical battery cell with a shape factor ratio (defined by the value obtained by dividing the diameter of the cylindrical battery cell by its height, i.e., the ratio of diameter (Φ) to height (H)) greater than about 0.4.

[0171] Here, the shape factor refers to the value representing the diameter and height of the cylindrical battery cell. The cylindrical battery cell according to embodiments of this disclosure can be, for example, a 461100 battery, a 48750 battery, a 481100 battery, a 48800 battery, or a 46800 battery. In the numerical value representing the shape factor, the first two digits represent the diameter of the cell, the last two digits represent the height of the cell, and the last digit 0 indicates that the cell has a circular cross-section.

[0172] The battery cell according to the embodiments of the present disclosure is a battery having a generally cylindrical shape, and may be a cylindrical battery cell having a diameter of about 46 mm, a height of about 110 mm and a shape factor ratio of about 0.418.

[0173] According to another embodiment of the present disclosure, the battery cell is a battery having a generally cylindrical shape, and may be a cylindrical battery cell having a diameter of about 48 mm, a height of about 75 mm, and a shape factor ratio of about 0.640.

[0174] According to another embodiment of the present disclosure, the battery cell is a battery having a generally cylindrical shape, and may be a cylindrical battery cell having a diameter of about 48 mm, a height of about 110 mm, and a shape factor ratio of about 0.418.

[0175] According to another embodiment of the present disclosure, the battery cell is a battery having a generally cylindrical shape, and may be a cylindrical battery cell having a diameter of about 48 mm, a height of about 80 mm, and a shape factor ratio of about 0.600.

[0176] According to another embodiment of the present disclosure, the battery cell is a battery having a generally cylindrical shape, and may be a cylindrical battery cell having a diameter of about 46 mm, a height of about 80 mm, and a shape factor ratio of about 0.575.

[0177] According to existing technology, battery cells with a form factor ratio of approximately 0.4 or less are used. In other words, according to existing technology, for example, 18650 batteries, 21700 batteries, etc., are used. An 18650 battery has a diameter of approximately 18 mm, a height of approximately 65 mm, and a form factor ratio of approximately 0.277. A 21700 battery has a diameter of approximately 21 mm, a height of approximately 70 mm, and a form factor ratio of approximately 0.300.

[0178] The battery cell according to the above embodiments can be used to manufacture battery packs.

[0179] Figure 14 This is a perspective view showing the structure of a battery pack according to an embodiment of the present disclosure.

[0180] Reference Figure 14 The battery pack 3 according to an embodiment of the present disclosure includes an assembly in which cylindrical secondary batteries 1 are electrically connected to each other, and a battery pack housing 2 housing the assembly. The cylindrical secondary battery 1 is a battery cell according to the above embodiment. In the drawings, for ease of explanation, components such as busbars for electrical connections between the cylindrical secondary batteries 1, the cooling unit, and external terminals are omitted.

[0181] Battery pack 3 can be installed in a vehicle. Examples of vehicles may include electric vehicles, hybrid vehicles, or plug-in hybrid vehicles. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0182] Figure 15 It is used to explain including Figure 11 A 3D view of the vehicle with battery pack 3.

[0183] See Figure 15 The vehicle 5 according to an embodiment of the present disclosure includes a battery pack 3 according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, the vehicle 5 operates by receiving power from the battery pack 3.

[0184] While this disclosure has been specifically shown and described with reference to exemplary embodiments thereof, it is not limited thereto, and those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. An electrode assembly, said electrode assembly being a core-type structure in which a first electrode and a second electrode, both having sheet shapes, and a diaphragm inserted between the first electrode and the second electrode are wound in one direction, wherein, Each of the first electrode and the second electrode includes: Uncoated portions formed on longer edge ends without an active material layer; and The coated portion is coated with an active material layer and formed on the area other than the uncoated portion. The first electrode includes at least one insulating layer that simultaneously covers at least a portion of the uncoated portion and at least a portion of the coated portion. At least a portion of the uncoated area is divided into multiple segments. The plurality of segments are bent toward the winding center of the electrode assembly in the radial direction, such that adjacent segments overlap each other in the radial direction of the electrode assembly. The insulating layer extends to the end of the uncoated portion on one of the two surfaces of the uncoated portion in a bending direction toward the winding center of the electrode assembly.

2. The electrode assembly of claim 1, wherein, The insulating layer is contained on both surfaces of the first electrode.

3. The electrode assembly of claim 1, wherein, The uncoated portion of the first electrode has a structure in which at least a portion of the uncoated portion is bent along the radial direction of the electrode assembly, and The insulating layer is disposed only on the surface of the first electrode facing the bending direction, which is the direction towards the winding center of the electrode assembly.

4. The electrode assembly of claim 1, wherein, One end of the insulating layer in the winding axis direction is located at the same height as one end of the diaphragm in the winding axis direction, or is located outside that end of the diaphragm in the winding axis direction.

5. The electrode assembly of claim 1, wherein, The uncoated portion protrudes further outward than the insulating layer.

6. The electrode assembly of claim 1, wherein, The coated portion does not protrude further than the diaphragm in the direction of the winding axis.

7. The electrode assembly of claim 1, wherein, The first electrode is the positive electrode.

8. The electrode assembly of claim 1, wherein, When the diaphragm is inserted between the second electrode and the insulating layer, the end of the second electrode facing the insulating layer does not protrude further outward than the end of the diaphragm facing the insulating layer.

9. The electrode assembly of claim 1, wherein, The coating portion includes a sliding portion, wherein the active material layer of the sliding portion has a reduced thickness compared to the central region of the coating portion.

10. The electrode assembly according to claim 9, wherein, The sliding portion is formed in the boundary region between the coated portion and the uncoated portion.

11. The electrode assembly according to claim 9, wherein, The sliding portion is included in one end of the first electrode in the winding axis direction and the other end of the second electrode in the winding axis direction.

12. The electrode assembly according to claim 9, wherein, The sliding portion of the coated portion included in the first electrode and the sliding portion of the coated portion included in the second electrode are contained in opposite directions to each other.

13. The electrode assembly according to claim 11, wherein, The diaphragm protrudes further outward than the other end of the first electrode in the direction of the winding axis and the other end of the second electrode in the direction of the winding axis.

14. The electrode assembly according to claim 9, wherein, The insulating layer covers at least a portion of the sliding portion.

15. The electrode assembly according to claim 1, wherein, The insulating layer covers the uncoated portion by 0.3 mm to 5 mm.

16. The electrode assembly according to claim 1, wherein, The insulating layer covers the uncoated portion by 1.5 mm to 3 mm.

17. The electrode assembly according to claim 1, wherein, The insulating layer covers the coated portion by 0.1 mm to 3 mm.

18. The electrode assembly according to claim 1, wherein, The insulating layer covers the coated portion by 0.2 mm to 0.5 mm.

19. The electrode assembly according to claim 1, wherein, The insulating layer surrounds the end of the uncoated portion.

20. The electrode assembly according to claim 1, wherein, The insulating layer extends on the surface opposite to the surface facing the bending direction on one of the two surfaces of the uncoated portion until the bending point of the uncoated portion.

21. The electrode assembly according to claim 1, wherein, The segment is provided only in a portion of a surface of the electrode assembly in the height direction.

22. The electrode assembly according to claim 21, wherein, The area of ​​the region on a surface of the electrode assembly in the height direction where the segment is formed is larger than the area of ​​the region where the segment is not formed.

23. The electrode assembly according to claim 21, wherein, An insulating layer disposed on one of the two surfaces of the uncoated portion in the bending direction of the uncoated portion has a shape that extends to the end of the uncoated portion in the region forming the segment, and a shape that does not extend to the end of the uncoated portion in the region where the segment is not formed.

24. The electrode assembly according to claim 1, wherein, The uncoated portion contained in the first electrode and the uncoated portion contained in the second electrode protrude in opposite directions to each other.

25. The electrode assembly according to claim 1, wherein, The length of the coated portion in the first electrode in the winding axis direction is less than the length of the coated portion in the second electrode in the winding axis direction.

26. The electrode assembly according to claim 1, wherein, The coated portion included in the first electrode is located inside the coated portion included in the second electrode in the direction of the winding axis.

27. The electrode assembly according to claim 1, wherein, The insulating layer is an insulating coating or insulating tape contained in the boundary region between the uncoated portion and the coated portion.

28. The electrode assembly according to claim 1, wherein, The insulating layer comprises an oil-based SBR adhesive and aluminum oxide.

29. A cylindrical secondary battery, the cylindrical secondary battery comprising: The electrode assembly according to any one of claims 1 to 28; A battery can housing the electrode assembly and electrically connected to the second electrode; A sealing body that seals the open end of the battery can; as well as Terminals that are electrically connected to the first electrode and have a surface exposed to the outside of the battery canister.

30. The cylindrical secondary battery of claim 29, further comprising a first current collector electrically connected to the uncoated portion of the first electrode.

31. The cylindrical secondary battery according to claim 30, wherein, The uncoated portion of the first electrode is electrically connected to the first current collector in the area of ​​its entire region not covered by the insulating layer.

32. The cylindrical secondary battery according to claim 31, wherein, The uncoated portion of the first electrode is connected to the first current collector by soldering in areas of its entire area not covered by the insulating layer.

33. A battery pack comprising a cylindrical secondary battery according to any one of claims 29 to 32.

34. A vehicle comprising the battery pack according to claim 33.

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