Cylindrical secondary battery including improved current collector, battery pack including same, and automobile

Abstract

The cylindrical secondary battery according to the present invention is a jelly-roll-type electrode assembly having a structure in which sheet-shaped positive and negative electrode plates and a separator interposed between the positive and negative electrode plates are wound in one direction, the positive electrode plate including a positive electrode uncoated portion exposed to the outside of the separator at a long edge thereof, and the negative electrode plate including a negative electrode uncoated portion exposed to the outside of the separator at a long edge thereof, a positive electrode current collector connected to the positive electrode uncoated portion by a positive electrode weld, and a negative electrode current collector connected to the negative electrode uncoated portion by a negative electrode weld, wherein a bonding area S1 between the positive electrode uncoated portion and the positive electrode current collector is smaller than a bonding area S2 between the negative electrode uncoated portion and the negative electrode current collector. According to the present invention, by improving the positive electrode current collector and the negative electrode current collector, it is possible to ensure kinetic balance between the positive and negative electrodes, improve energy density, and strengthen the bonding strength between the components.

Description

[Technical field]

[0001] The present invention relates to a secondary battery, more particularly to a current collector plate and a cylindrical secondary battery including the same. The present invention also relates to a battery pack and a vehicle including such a cylindrical secondary battery.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0147346 filed on October 29, 2021, and Korean Patent Application No. 10-2021-0187847 filed on December 24, 2021, and the entire contents disclosed in the specification and drawings of said applications are incorporated herein by reference. [Background technology]

[0003] As technological development and demand for mobile devices and electric vehicles increases, the demand for secondary batteries as an energy source is rapidly increasing. Currently, the most widely used secondary battery is the lithium ion battery, and cylindrical, square and pouch-type secondary batteries are known. In the case of a cylindrical secondary battery, a separator, which is an insulator, is interposed between a positive electrode plate and a negative electrode plate, and the electrode plate is wound up to form a jelly-roll-shaped electrode assembly, which is then inserted into a battery can. Each electrode plate includes an active material layer coated on a current collector.

[0004] In lithium secondary batteries, the parts that have the greatest impact on charge / discharge characteristics such as capacity and cycle life are the positive and negative electrodes where electrochemical reactions occur. In particular, charge / discharge characteristics are affected by the reaction speed of the positive and negative electrodes in the process of lithium ions (Li+) moving through the electrolyte due to oxidation-reduction reactions at the electrodes. Therefore, when a kinetic balance is achieved in which the reaction speeds of the positive and negative electrodes are in balance, fast charging is performed as intended and cycle characteristics are improved. Therefore, in order to facilitate fast charging and improve the cycle characteristics of the battery, it is necessary to ensure a kinetic balance between the positive and negative electrodes.

[0005] Kinetic balance can be achieved by making the lithium ion migration speeds in the positive and negative electrodes similar. The lithium ion migration speed is mainly determined by the resistance caused by the active material layer coated on the electrode plate. This resistance refers to the resistance that prevents charge transfer of lithium ions inside and on the surface of the active material particles. The resistance varies depending on the types of materials that make up the active material layer of the electrode plate, such as the active material, binder, and conductive material, and can also vary depending on the distribution state of the binder and conductive material on the surface of the active material particles.

[0006] Conventionally, the lithium ion migration speed has been controlled by adjusting the composition of the active material layer coated on the electrode plate, which is called a chemistry balance adjustment. However, there is a problem that the controllable range of the lithium ion migration speed is very narrow only by applying the chemistry balance adjustment method. This is because the composition range of the active material layer that can actually be used in a lithium secondary battery is limited to a certain extent. When trying to adjust the lithium ion migration speed within the limit of the process implementation capability due to the composition of the active material layer, only a relatively narrow range of adjustment is possible. Therefore, there is a need to develop a technology that enables the lithium ion migration speed to be controlled in a more meaningful range than the control of the lithium ion migration speed by the chemistry balance adjustment.

[0007] Meanwhile, in the past, a strip-shaped current collecting tab was connected to an uncoated portion of an electrode plate, which is an area where an active material layer is not coated, and the current collecting tab was used to electrically connect the electrode assembly to an electrode terminal exposed to the outside. For reference, the positive electrode terminal is a cap plate of a sealed body that seals an opening of a battery can, and the negative electrode terminal is the battery can. However, in the conventional cylindrical secondary battery having such a structure, current is concentrated in the current collecting tab, which causes a problem of high resistance, large heat generation, and poor current collection efficiency.

[0008] In a small cylindrical secondary battery having a form factor of 18650 or 21700, resistance and heat generation are not a big problem. However, when the form factor of a cylindrical secondary battery is increased to apply it to an electric vehicle, a problem of the cylindrical secondary battery catching fire may occur due to a large amount of heat generated around the current collecting tab during a fast charging process. To solve this problem, a cylindrical secondary battery (so-called tab-less cylindrical secondary battery) having a structure in which a positive electrode uncoated portion and a negative electrode uncoated portion are respectively located at the upper end and the lower end of a jelly roll type electrode assembly and a current collecting plate is directly welded to these uncoated portions to improve current collection efficiency may be used.

[0009] In a table-less cylindrical secondary battery, the welded portion between the non-coated portion and the current collector plate constitutes the current path, so the current collector plate is a part that must be managed with great care. It is necessary to maximize the contact area between the current collector plate and the non-coated portion as much as possible, thereby minimizing the resistance that occurs at the connection between the parts.

[0010] However, in the past, the focus was on minimizing resistance, and no consideration was given to the individual characteristics of the positive current collector welded to the uncoated positive portion and the negative current collector welded to the uncoated negative portion, and they were vaguely treated as having the same or similar structure, which resulted in limitations to the performance of the secondary battery that could be implemented. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention aims to make it possible to control the lithium ion migration rate over a larger range than the above-mentioned technology of controlling the lithium ion migration rate by adjusting the chemical balance between the positive electrode and the negative electrode.

[0012] Another object of the present invention is to improve the performance of a cylindrical secondary battery by improving the positive and negative current collectors in a tabless cylindrical secondary battery.

[0013] Accordingly, the problem to be solved by the present invention is to provide a cylindrical secondary battery including an improved current collector plate.

[0014] Another technical object of the present invention is to provide a battery pack and an automobile including such a secondary battery.

[0015] However, the technical problems that the present invention aims to solve are not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0016] The present inventor discovered that by improving the positive and negative current collectors of a cylindrical secondary battery, it is possible to ensure the kinetic balance between the positive and negative electrodes, improve the energy density, and strengthen the bonding strength between the components, thereby completing the present invention.

[0017] In order to solve the above problems, a cylindrical secondary battery according to the present invention includes a jelly-roll type electrode assembly having a structure in which sheet-shaped positive and negative electrode plates and a separator interposed between the positive and negative electrode plates are wound in one direction, the positive electrode plate includes a positive non-coated portion exposed to the outside of the separator at a long side end, and the negative electrode plate includes a negative non-coated portion exposed to the outside of the separator at a long side end, a positive current collector plate connected to the positive non-coated portion by a positive electrode weld, and a negative current collector plate connected to the negative non-coated portion by a negative electrode weld, and a bonding area S1 between the positive non-coated portion and the positive current collector plate is smaller than a bonding area S2 between the negative non-coated portion and the negative current collector plate.

[0018] In one aspect, the number of the negative electrode welds may be greater than the number of the positive electrode welds.

[0019] Here, the positive electrode welded portion and the negative electrode welded portion may be formed to extend along a radial direction of the electrode assembly.

[0020] In another aspect, the positive collector plate may cover an upper end of the electrode assembly, and the negative collector plate may cover a lower end of the electrode assembly.

[0021] Here, the positive collector plate includes one or more strips extending from a center of the positive collector plate in a radial direction of the electrode assembly, and the positive weld is formed on the strip of the positive collector plate, and the negative collector plate includes one or more strips extending from a center of the negative collector plate in a radial direction of the electrode assembly, and the negative weld is formed on the strip of the negative collector plate.

[0022] In yet another aspect, the positive current collector strips may be two or more and equally spaced apart from one another, and the negative current collector strips may be two or more and equally spaced apart from one another.

[0023] In yet another aspect, the number of strips of the positive current collector plate may be less than the number of strips of the negative current collector plate. For example, the number of strips of the negative current collector plate may be M, and the number of strips of the positive current collector plate may be 1 to M-1 (M is a natural number equal to or greater than 2). For example, the number of strips of the positive current collector plate may be 3, and the number of strips of the negative current collector plate may be 4.

[0024] The ratio S1 / S2 of the bonding area S1 between the positive electrode uncoated portion and the positive electrode current collector plate and the bonding area S2 between the negative electrode uncoated portion and the negative electrode current collector plate may be in the range of 1 / M to (M-1) / M (M is a natural number of 2 or more).

[0025] In another example, the number of the positive electrode welds may be less than the number of the negative electrode welds.

[0026] In yet another example, the number of the positive electrode welds and the number of the negative electrode welds may be the same, and the area of ​​one of the positive electrode welds may be smaller than the area of ​​one of the negative electrode welds.

[0027] The positive and negative current collector plates may have the same outer shapes as the upper and lower ends of the electrode assembly, respectively.

[0028] In one embodiment, the cylindrical secondary battery further includes a battery can that receives the electrode assembly through an opening formed on one side thereof and is electrically connected to the negative electrode uncoated portion, a cap plate configured to seal the opening of the battery can, and a rivet terminal that is insulatively installed in a through-hole formed in a center of a closed portion located on the opposite side to the opening of the battery can and is electrically connected to the positive electrode uncoated portion.

[0029] Preferably, the cap plate is not connected to the electrode assembly and has no polarity.

[0030] In one embodiment, the positive current collector plate includes a peripheral portion, a positive tab coupling portion extending inward from the peripheral portion and coupled to the positive non-coated portion by the positive welded portion, and a terminal coupling portion spaced apart from the positive tab coupling portion, and the rivet terminal is coupled to the terminal coupling portion.

[0031] Preferably, the cylindrical secondary battery further includes an insulator interposed between the closing portion and the positive current collector plate, and the rivet terminal may penetrate the insulator and be coupled to the terminal coupling portion.

[0032] In one aspect, the peripheral edge may have a rim configuration with at least a portion of the inner region being open.

[0033] Preferably, the positive electrode tab connection portion and the terminal connection portion may be electrically connected by the peripheral portion.

[0034] Also, the terminal coupling portion may be located at a center of the inner space of the peripheral portion.

[0035] Preferably, the positive electrode tab connector may include a plurality of positive electrode tab connectors.

[0036] In this case, the positive electrode tab coupling portions may be disposed at equal intervals from one another along the circumferential direction.

[0037] In addition, the extension lengths of the positive electrode tab coupling portions may be the same as each other.

[0038] Furthermore, the terminal connection portion may be arranged to be surrounded by a plurality of the positive electrode tab connection portions.

[0039] In one embodiment, the electrode assembly may include a cavity in a winding center portion of the electrode assembly, and the terminal coupling portion may be disposed at a position corresponding to the cavity.

[0040] Preferably, at least a portion of the positive electrode uncoated portion may be divided into a plurality of segments, and the plurality of segments may be bent in a radial direction of the electrode assembly.

[0041] Preferably, the plurality of segments may be overlapped in multiple layers along a radial direction of the electrode assembly.

[0042] In one aspect, the positive electrode current collector plate includes a peripheral portion, a positive electrode tab coupling portion extending inward from the peripheral portion and coupled to the positive electrode uncoated portion by the positive electrode welding portion, and a terminal coupling portion spaced apart from the positive electrode tab coupling portion, and the positive electrode tab coupling portion may be coupled to a region where the plurality of segment pieces are overlapped in multiple layers.

[0043] In one embodiment, the battery can includes a beading portion formed at an end adjacent to the opening and pressed inward, and the negative current collector plate includes a negative tab connecting portion connected to the negative non-coated portion by the negative welded portion, and a can connecting portion electrically connected to the beading portion.

[0044] The can bond may extend from the negative tab bond.

[0045] In another example, the negative electrode tab coupling portion and the can coupling portion may be indirectly coupled to each other through the center portion of the negative electrode current collector plate, and may not be directly coupled to each other.

[0046] The negative electrode tab connector may include at least one liquid injection hole.

[0047] In another aspect of the present invention, the negative current collector plate may include a circular negative current collector hole at a center of the negative current collector plate.

[0048] The electrode assembly may include a cavity in a winding center of the electrode assembly, and a diameter of the negative electrode current collector hole may be the same as or larger than a diameter of the cavity.

[0049] Preferably, the negative electrode current collector plate may have a leg structure extending in a radial direction of the electrode assembly with the negative electrode tab coupling portion and the can coupling portion being connected to each other.

[0050] The leg structure may include a plurality of leg structures.

[0051] Preferably, a plurality of the can coupling parts may be included, and the plurality of the can coupling parts may be connected to each other to be integrally formed.

[0052] In an embodiment of the present invention, at least a portion of the negative electrode uncoated portion may be divided into a plurality of segments, and the plurality of segments may be bent in a radial direction of the electrode assembly.

[0053] Preferably, the plurality of segments may be overlapped in multiple layers along a radial direction of the electrode assembly.

[0054] Preferably, the negative electrode current collector plate may include a negative electrode tab coupling portion coupled to the negative electrode uncoated portion by the negative electrode welding portion, and a can coupling portion electrically coupled to the beading portion, and the negative electrode tab coupling portion may be coupled to a region where the plurality of segment pieces are overlapped in multiple layers.

[0055] In an embodiment of the present invention, the positive electrode welded portion may be formed for each of the positive electrode tab coupling portions, and the negative electrode welded portion may be formed for each of the negative electrode tab coupling portions, and the number of the positive electrode tab coupling portions may be less than the number of the negative electrode tab coupling portions.

[0056] Preferably, the positive and negative welded portions may be formed to extend in a radial direction of the electrode assembly.

[0057] In another example, the positive electrode welds may be formed for each of the positive electrode tab coupling parts, and the negative electrode welds may be formed for each of the negative electrode tab coupling parts, and the number of the positive electrode welds may be less than the number of the negative electrode welds.

[0058] In yet another example, the positive electrode welds may be formed for each of the positive electrode tab coupling portions, the negative electrode welds may be formed for each of the negative electrode tab coupling portions, the number of the positive electrode welds may be the same as the number of the negative electrode welds, and an area of ​​one of the positive electrode welds may be smaller than an area of ​​one of the negative electrode welds.

[0059] In another aspect, the battery can may include a crimping portion formed closer to the opening than the beading portion and extending and bent toward the opening.

[0060] Preferably, the can joint portion can be pressed and fixed by the crimping portion.

[0061] The can coupling portion may include a contact portion coupled to the beading portion by welding, and a connection portion connecting the negative electrode tab coupling portion and the contact portion.

[0062] Preferably, the contact portion may be joined to the beading portion by welding.

[0063] Preferably, the contact portion may be an arc extending in a circumferential direction along the beading portion of the battery can.

[0064] In still another aspect, the cylindrical secondary battery may further include a sealing gasket between the battery can and the cap plate, and the contact portion may be interposed between the sealing gasket and the beading portion.

[0065] In one example, the peripheral portion, the positive electrode tab connection portion, and the terminal connection portion of the positive electrode current collector plate may all be located on the same plane.

[0066] In another example, the negative electrode tab coupling portion and the can coupling portion of the negative electrode current collector plate do not need to be located on the same plane.

[0067] The present invention provides a battery pack including at least one such cylindrical secondary battery, and a vehicle including at least one such battery pack. Effect of the Invention

[0068] According to one aspect of the present invention, the lithium ion migration speed can be controlled by making the bonding area S1 between the positive electrode uncoated portion and the positive electrode current collector smaller than the bonding area S2 between the negative electrode uncoated portion and the negative electrode current collector. It is not necessary to adjust the chemical balance between the positive electrode and the negative electrode, and the lithium ion migration speed can be controlled in a wider range than the chemical balance adjustment method without adjusting the chemical balance between the positive electrode and the negative electrode. It is possible to provide a cylindrical secondary battery that is capable of adjusting the lithium ion migration speed, is easy to fast charge, and has excellent cycle characteristics while maintaining the conventional process window within the limit range of process implementation capability according to the composition of the active material.

[0069] The cylindrical secondary battery according to the present invention is very suitable for large batteries with an increased form factor. A cylindrical secondary battery having a structure with improved current collection efficiency, i.e., a tabless cylindrical secondary battery, can be manufactured by designing a positive electrode uncoated portion and a negative electrode uncoated portion to be located at the upper and lower ends of a jelly roll type electrode assembly, respectively, and welding a positive electrode current collector to the positive electrode uncoated portion and a negative electrode current collector to the negative electrode uncoated portion. According to the present invention, the non-coated portions protruding from the upper and lower ends of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the secondary battery and increasing the energy density.

[0070] When a cylindrical secondary battery is applied to a device such as an automobile, it may be frequently subjected to external impacts and vibrations during use, which may cause damage to the joints for electrical connection between the components. Such damage to the joints may cause product defects. Even if the joints for electrical connection are damaged and the electrical connection is not completely cut off, if the welded parts are partially damaged and the joint area between the components is reduced, problems such as excessive heat generation due to increased resistance and internal short circuit due to deformation of the parts may occur. According to another aspect of the present invention, a cylindrical secondary battery including a positive electrode current collector having a structure that does not concentrate force on the joints between the components even when external impacts and / or vibrations are applied during use is provided, thereby improving the mechanical and electrical performance of the secondary battery.

[0071] According to yet another aspect of the present invention, there is provided a cylindrical secondary battery including a negative electrode current collector having a structure suitable for an electrode assembly having a low resistance structure. Such a negative electrode current collector not only has a structure that improves the bonding strength of the bonding site with the battery can, but also can improve the energy density of the cylindrical secondary battery. As a result, the mechanical and electrical performance of the cylindrical secondary battery is improved.

[0072] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0073] [Figure 1] 2 is a view illustrating an electrode assembly included in a cylindrical secondary battery according to an embodiment of the present invention; [Diagram 2] 1 is a schematic diagram of a cylindrical secondary battery according to an embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram showing a positive electrode current collector plate and a negative electrode current collector plate according to a comparative example. [Figure 4] 2A and 2B are diagrams illustrating a positive electrode current collector plate and a negative electrode current collector plate according to an embodiment of the present invention. [Diagram 5] 5A and 5B are diagrams showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention. [Figure 6] 5A and 5B are diagrams showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention. [Figure 7] 5A and 5B are diagrams showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention. [Figure 8] 5A and 5B are diagrams showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention. [Figure 9] 5A and 5B are diagrams showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention. [Figure 10] FIG. 2 is a perspective view of a cylindrical secondary battery according to another embodiment of the present invention. [Figure 11] 11 is a vertical sectional view of the cylindrical secondary battery of FIG. 10. [Figure 12] 5 is a view illustrating an electrode assembly included in a cylindrical secondary battery according to another embodiment of the present invention. [Figure 13] 13 is a vertical sectional view of a cylindrical secondary battery including the electrode assembly of FIG. 12. [Figure 14] 1A to 1C are diagrams showing various forms of a positive electrode current collector plate. [Figure 15] 1A to 1C are diagrams showing various forms of a positive electrode current collector plate. [Figure 16] 1A to 1C are diagrams showing various forms of a positive electrode current collector plate. [Figure 17] 1A to 1C are diagrams showing various forms of a positive electrode current collector plate. [Figure 18] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 19] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 20] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 21] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 22] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 23] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 24] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Diagram 25] 1A to 1C are diagrams showing various forms of a negative electrode current collector plate. [Figure 26] 1 is a schematic diagram illustrating a battery pack according to an embodiment of the present invention. [Figure 27] FIG. 1 shows a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts according to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0075] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0076] In order to facilitate understanding of the present invention, the accompanying drawings may be drawn not to scale but with some components exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0077] FIG. 1 is a view illustrating an electrode assembly included in a cylindrical secondary battery according to an embodiment of the present invention.

[0078] 1, the electrode assembly 10 is a jelly roll type electrode assembly having a structure in which a positive electrode plate 12, a negative electrode plate 14, and a separator 16 interposed therebetween are wound in one direction. The electrode assembly 10 can be manufactured by stacking the positive electrode plate 12, the separator 16, the negative electrode plate 14, and the separator 16 in this order at least once, and winding the stacked body around a winding center C. After winding is completed, the electrode assembly 10 has a substantially cylindrical shape. When viewed from the top or bottom of the electrode assembly 10, the outer shape of the electrode assembly 10 is circular.

[0079] The positive electrode plate 12 has a structure in which a positive electrode active material layer 12b is coated on one or both sides of a sheet-shaped positive electrode collector having long and short sides, and includes a positive electrode uncoated portion 12a at an end of one long side along the winding direction X. The positive electrode uncoated portion 12a may be continuously formed along one side of the positive electrode plate 12. The negative electrode plate 14 also has a structure in which a negative electrode active material layer 14b is coated on one or both sides of a sheet-shaped negative electrode collector having long and short sides, and includes a negative electrode uncoated portion 14a at an end of one long side along the winding direction X where the active material layer is not coated. The negative electrode uncoated portion 14a may also be continuously formed along one side end of the negative electrode plate 14.

[0080] The current collector can be appropriately selected according to the polarity of the electrode plate, and the material thereof can be aluminum, copper, nickel or stainless steel, but is not necessarily limited thereto, and can be any metal or metal alloy commonly used as a current collector material. For example, the positive electrode current collector can be aluminum or an aluminum alloy, and the negative electrode current collector can be copper or a copper alloy.

[0081] In the present invention, the positive electrode active material coated on the positive electrode current collector and the negative electrode active material coated on the negative electrode current collector may be any active material known in the art without any limitations.

[0082] In one example, the positive electrode active material is represented by the general chemical formula A[A x M y ]O 2+z (A includes at least one or more elements of Li, Na, and K; M includes at least one or more elements 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; the stoichiometric coefficients x, y, and z are selected to maintain the compound electrically neutral).

[0083] Preferably, the positive electrode active material includes a lithium transition metal oxide, and may include nickel-cobalt-manganese-based lithium oxide, particularly high-concentration nickel-cobalt-manganese-based lithium oxide having a high nickel content in the fiber metal.

[0084] In another example, the positive electrode active material is an alkali metal compound xLiM disclosed in US Pat. No. 6,677,082, US Pat. No. 6,680,143, etc. 1 O 2 -(1-x)Li 2 M 2 O 3 (M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0≦x≦1).

[0085] In yet another embodiment, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M1 contains at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, and Al; M 2 contains at least one or more elements selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 contains a halogen group element selectively containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y, and z are selected so that the compound maintains electrical neutrality.), or Li 3 M 2 (PO 4 ) 3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg, and Al] can be a lithium metal phosphate represented by

[0086] Desirably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregation of primary particles.

[0087] In one 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 TiO 2 and SnO 2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, low-crystalline carbon, high-crystalline carbon, etc. can all be used.

[0088] The separation membrane 16 can be used alone or in a laminated form a porous polymer film made of a polyolefin-based polymer such as, for example, a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc. As another example, the separation membrane 16 can use a normal porous nonwoven fabric, for example, a nonwoven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc.

[0089] At least one surface of the separation membrane 16 may include a coating layer of inorganic particles. The separation membrane 16 itself may also be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that there is an interstitial volume between adjacent particles.

[0090] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT), PB(Mg 3 Nb 2 / 3 )O 3 -PbTiO 3 (PMN-PT), BaTiO 3 , hafnia (HfO 2 ), SrTiO 3 , TiO 2 , Al 2 O 3 , ZrO 2 , SnO 2 , CEO 2 , MgO, CaO, ZnO and Y 2 O 3 The composition may include at least one material selected from the group consisting of:

[0091] An insulating coating layer 18 may be further formed at the boundary between the active material layers 12b, 14b and the non-coated portions 12a, 14a. The insulating coating layer 18 may be formed so that at least a portion of the insulating coating layer 18 overlaps with the boundary between the active material layers 12b, 14b and the non-coated portions 12a, 14a. The insulating coating layer 18 includes a polymer resin and is made of Al. 2 O 3The insulating coating layer 18 may include an inorganic filler such as a filler containing an inorganic material. The insulating coating layer 18 can effectively prevent electrical contact between the positive electrode plate 12 and the negative electrode plate 14. The insulating coating layer 18 may be omitted. The insulating coating layer 18 may play a role of providing mechanical support laterally to prevent the non-coated portions 12a, 14a from being excessively bent toward the separator 16 when the non-coated portions 12a, 14a are folded.

[0092] The uncoated portions 12a, 14a are disposed in opposite directions to each other and are exposed to the outside of the separator 16. In the electrode assembly 10, at least a portion of the positive electrode uncoated portion 12a can be used as a positive electrode tab, and at least a portion of the negative electrode uncoated portion 14a can be used as a negative electrode tab.

[0093] FIG. 2 is a schematic diagram of a cylindrical secondary battery according to one embodiment of the present invention.

[0094] 2, a cylindrical secondary battery 20 may include the electrode assembly 10 described with reference to Fig. 1. The cylindrical secondary battery 20 further includes a positive electrode current collector 22 and a negative electrode current collector 24. These may be housed together with an electrolyte in a battery can (not shown), which is an outer case.

[0095] The electrolyte is A + B - In this case, the salt may have the structure: + Li + , Na + , K + and combinations of these cations. - F - , Cl - , Br - , I - , NO 3 - , N(CN) 2 - , B.F. 4 - , ClO 4 - , AlO 4 - , AlCl4 - 、PF 6 - 、SbF 6 - 、AsF 6 - 、BF 2 C 2 O 4 - 、BC 4 O 8 - 、(CF 3 ) 2 PF 4 - 、(CF 3 ) 3 PF 3 - 、(CF 3 ) 4 PF 2 - 、(CF 3 ) 5 PF - 、(CF 3 ) 6 P - 、CF 3 SO 3 - 、C 4 F 9 SO 3 - 、CF 3 CF 2 SO 3 - 、(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - 、CF 3 CF 2 (CF 3 ) 2 CO - 、(CF 3 SO 2 ) 2 CH - 、(SF 5 ) 3 C - 、(CF 3 SO 2 ) 3 C - 、CF3 (CF 2 ) 7 SO 3 - , C.F. 3 CO 2 - , C.H. 3 CO 2 - , SCN - and (CF 3 CF 2 SO 2 ) 2 N - The anion includes one or more anions selected from the group consisting of:

[0096] The electrolyte may be dissolved in an organic solvent and used as an electrolytic solution. Examples of the organic solvent that may be used include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, and mixtures thereof.

[0097] In the electrode assembly 10 of Fig. 1, each of the uncoated portions 12a, 14a is not coupled with a separate current collecting tab, and is used as an electrode tab by itself. The electrode assembly 10 includes the positive electrode uncoated portion 12a at the upper end of the electrode assembly 10, and the negative electrode uncoated portion 14a at the lower end of the electrode assembly 10. In other words, the positive electrode uncoated portion 12a is provided at the upper portion of the electrode assembly 10 in the height direction (direction parallel to the Z axis), and the negative electrode uncoated portion 14a is provided at the lower portion of the electrode assembly 10 in the height direction.

[0098] 2, the positive current collector 22 covers the upper end of the electrode assembly 10, and the negative current collector 24 covers the lower end of the electrode assembly 10, and may be housed in a battery can (not shown). The positive current collector 22 and the negative current collector 24 may have the same outer shape as the upper and lower ends of the electrode assembly 10. For example, the positive current collector 22 and the negative current collector 24 may be disk-shaped. Of course, the specific shapes of the positive current collector 22 and the negative current collector 24 and their positions within the battery can may vary differently from those shown in the drawings.

[0099] The positive current collector 22 may be made of the same metal as the positive current collector of the positive plate 12 of the electrode assembly 10, or may be made of a material that is easy to weld to the positive current collector. The negative current collector 24 may be made of the same metal as the negative current collector of the negative plate 14 of the electrode assembly 10, or may be made of a material that is easy to weld to the negative current collector. For example, the positive current collector 22 may be aluminum or an aluminum alloy, steel, stainless steel, or the like, and the negative current collector 24 may be copper or a copper alloy, nickel or a nickel alloy, steel, stainless steel, or a composite material thereof. For example, the negative current collector 24 may be a clad metal in which nickel is plated on copper.

[0100] The positive current collector 22 is coupled to the positive non-coated portion 12a of the electrode assembly 10. The negative current collector 24 is coupled to the negative non-coated portion 14a of the electrode assembly 10. The positive non-coated portion 12a and the positive current collector 22 are directly coupled to each other by welding. The negative non-coated portion 14a and the negative current collector 24 are also directly coupled to each other by welding. A weld is formed at each welding portion. The present invention is not limited by the type of the positive current collector 22 to be welded at the position of the positive non-coated portion 12a and the type of the negative current collector 24 to be welded at the position of the negative non-coated portion 14a. Examples of welding methods include, but are not limited to, laser welding, resistance welding, and ultrasonic welding.

[0101] Each current collector 22, 24 guides the current generated in each electrode plate 12, 14 of the electrode assembly 10 to each electrode terminal. Each current collector 22, 24 can be considered to be a component that is connected to lead out current from each non-coated portion 12a, 14a, which is the end of each electrode plate 12, 14. In order to weld each current collector 22, 24 to each non-coated portion 12a, 14a, the non-coated portion 12a, 14a forming the end of the electrode assembly 10 wound in a jelly roll type may be folded flat to bring into surface contact with each current collector 22, 24, and then laser welding may be performed.

[0102] Preferably, each of the non-coated portions 12a, 14a is bent toward the winding center C of the electrode assembly 10 as shown in FIG. 2. The bent state of the positive non-coated portion 12a can be seen from the enlarged view of part A. The bent state of the negative non-coated portion 14a is similar to this. After each of the non-coated portions 12a, 14a is bent, each of the current collectors 22, 24 is welded to each of the non-coated portions 12a, 14a. The positive non-coated portion 12a serves as a positive tab, the negative non-coated portion 14a serves as a negative tab, and the positive current collector 22 and the negative current collector 24 are connected to external electrode terminals, so that a current path is formed with a large cross-sectional area in the winding axial direction of the electrode assembly 10 (see arrow), thereby reducing the resistance of the secondary battery. This structure is particularly suitable for high-power secondary batteries.

[0103] Since the current collectors 22 and 24 are welded directly to the non-coated portions 12a and 14a, respectively, to introduce and extract current, no separate current collecting tabs are required. As a result, the installation process of the current collecting tabs is eliminated, improving productivity. In addition, since the space for storing the end tabs can be reduced, the secondary battery as a whole becomes more compact, improving space utilization.

[0104] Here, it is important that the bonding area S1 between the positive electrode non-coated portion 12a and the positive electrode current collector 22 is smaller than the bonding area S2 between the negative electrode non-coated portion 14a and the negative electrode current collector 24 (S1 < S2). The bonding between each non-coated portion and each current collector is achieved by a welded portion. The welded portion serves as a current path from the non-coated portion to the current collector and from the current collector to the non-coated portion, and the area of the welded portion, i.e., the welding area, becomes the bonding area or the direct contact area between the current collector and the non-coated portion. As the bonding area increases, the current path becomes wider, reducing the resistance. By making the bonding area S1 between the positive electrode non-coated portion 12a and the positive electrode current collector 22 smaller than the bonding area S2 between the negative electrode non-coated portion 14a and the negative electrode current collector 24, the resistance in the positive electrode is increased, and the kinetic balance between the positive electrode and the negative electrode can be adjusted.

[0105] Although various types of active materials were exemplified earlier, within the range of the types of positive and negative active materials commonly used, the lithium ion migration rate in the positive electrode tends to be faster than that in the negative electrode. When there is a significant difference in the lithium ion migration rate in each electrode, battery reactions such as charge and discharge do not occur smoothly. Specifically, during charging, lithium ions from the positive electrode should move to the negative electrode. In the positive electrode, the lithium ion migration rate is fast, but in the negative electrode, the lithium ion migration rate is slow. If the lithium ions migrating from the positive electrode cannot move smoothly on the negative electrode side and stagnate, damage such as lithium precipitation occurs. This becomes more serious during rapid charging. Therefore, it is desirable to adjust the kinetic balance between the positive electrode and the negative electrode by intentionally reducing the lithium ion migration rate in the positive electrode.

[0106] Of course, it is also possible to balance the kinetics of the positive electrode and the negative electrode by increasing the migration rate of lithium ions in the negative electrode. However, this method is a chemical balance method such as increasing the porosity of the negative electrode to secure more space for lithium ions to migrate or increasing the content of the conductive material contained in the negative electrode active material layer. In the former case, since the thickness of the negative electrode plate is increased, it is not desirable in terms of energy density, and in the latter case, there is a problem of cost increase, which is not desirable industrially. Accordingly, it is desirable to lower the migration rate of lithium ions in the positive electrode within the range allowed by the process margin. The conventional method for lowering the migration rate of lithium ions in the positive electrode is a chemical balance method such as lowering the content of the conductive material contained in the positive electrode active material layer. Since the composition range of the active material layer that can actually be used in a lithium secondary battery is determined to some extent, there is a limit to the extent that can be adjusted by such a chemical balance method.

[0107] The present invention does not adjust the resistance by the composition of the positive electrode active material and the negative electrode active material like the chemical balance method to adjust the migration rate of lithium ions, but adjusts the resistance by the bonding area between the current collector plate and the non-coated part in each electrode, so as to affect the migration rate of lithium ions in each electrode plate. Specifically, by making the bonding area S1 between the positive electrode current collector plate and the positive electrode non-coated part smaller than the bonding area S2 between the negative electrode current collector plate and the negative electrode non-coated part, the resistance in the positive electrode current collector plate is made larger than the resistance in the negative electrode current collector plate. During charging, if electrons do not move from the positive electrode to the negative electrode, lithium ions moving from the positive electrode cannot be received at the negative electrode. By increasing the resistance of the positive electrode to cause a kind of bottleneck phenomenon in the flow of electrons trying to move from the positive electrode to the negative electrode, the migration rate of lithium ions in the positive electrode is reduced.

[0108] Hereinafter, various embodiments for embodying the relationship of S1 < S2 will be described.

[0109] First, to aid understanding, a comparative example where S1 = S2 will be described. FIG. 3 is a diagram showing the positive electrode current collector plate and the negative electrode current collector plate according to the comparative example.

[0110] Referring to FIG. 3, the positive electrode current collector plate 32 and the negative electrode current collector plate 34 are illustrated in a disc form. In FIG. 3, the area of one positive electrode welding portion 32a formed between the positive electrode non - coating portion (12a in FIG. 2) and the positive electrode current collector plate 32, and the area of one negative electrode welding portion 34a formed between the negative electrode non - coating portion (14a in FIG. 2) and the negative electrode current collector plate 34 are the same as each other, and the number of the positive electrode welding portions 32a and the number of the negative electrode welding portions 34a are the same. That is, without distinction between the positive electrode current collector plate 32 and the negative electrode current collector plate, the areas of the portions welded to the non - coating portions in each current collector plate (welding area or bonding area) are the same as each other.

[0111] On the other hand, FIG. 4 is a diagram showing the positive electrode current collector plate and the negative electrode current collector plate according to an embodiment of the present invention.

[0112] Referring to FIG. 4, the area of one positive electrode welding portion 22a formed between the positive electrode non - coating portion (12a in FIG. 2) and the positive electrode current collector plate 22, and the area of one negative electrode welding portion 24a formed between the negative electrode non - coating portion (14a in FIG. 2) and the negative electrode current collector plate 24 are the same as each other, and the number of the negative electrode welding portions 24a is larger than the number of the positive electrode welding portions 22a. FIG. 4 shows a case where the number of the positive electrode welding portions 22a is 3 and the number of the negative electrode welding portions 24a is 4. Thus, by making the areas of the welding portions the same and adjusting the number of the welding portions, the relationship between the bonding area S1 of the positive electrode non - coating portion 12a and the positive electrode current collector plate 22 and the bonding area S2 of the negative electrode non - coating portion 14a and the negative electrode current collector plate 24 can be made such that S1 < S2.

[0113] As shown in the figure, the positive electrode weld 22a and the negative electrode weld 24a may be formed to extend along the radial direction of the electrode assembly 10. Each of the welds 22a, 24a may include a weld bead. The size and shape of the weld bead constituting the welds 22a, 24a may vary. For example, the weld bead may be a single circle formed by spot welding. The weld bead may be a shape in which multiple circles are stacked. The stacked circles may form a single continuous line or may be substantially triangular. The welds include not only weld beads that are formed separately and thus distinct from one another, but also weld beads in which parts of the weld beads are stacked to form a single mass. Although FIG. 4 shows a case in which each of the welds 22a, 24a forms a continuous line, it does not exclude a case in which a single circle extends discontinuously and sparsely along the radial direction of the electrode assembly 10. When multiple weld beads are formed, the total weld area is determined by adding up the areas of the weld beads.

[0114] Furthermore, the weld bead is not formed flatly only on the surfaces of the two components that are joined by welding, but has a three-dimensional shape with a thickness that reaches at least the contact interface between the two components. In this specification, the "area of ​​the weld" can be said to be the cross-sectional area of ​​the weld bead at the contact interface between the current collector plate and the non-coated part. However, the cross-sectional area at the contact interface is difficult to control as a design factor. In the case of welding in a steady state, a correspondence relationship is established between the cross-sectional area at the contact interface and the area at the surface. Thus, the area at the surface, which is easy to control as a design factor, is defined as the area of ​​the weld.

[0115] 5 shows a positive current collector plate and a negative current collector plate according to another embodiment. While the positive current collector plate 22 and the negative current collector plate 24 shown in FIG. 4 are disk-shaped, the shapes of the positive current collector plate 22 and the negative current collector plate 24 in FIG. 5 are changed.

[0116] Referring to FIG. 5, the positive current collector 22 includes one or more strips 22b extending in the radial direction of the electrode assembly 10 from the central portion of the positive current collector 22. A positive welding portion 22a is formed on the strip 22b of the positive current collector 22 to be coupled to the positive non-coated portion 12a. The negative current collector 24 also includes one or more strips 24b extending in the radial direction of the electrode assembly 10 from the central portion of the negative current collector 24. A negative welding portion 24a is formed on the strip 24b of the negative current collector 24 to be coupled to the negative non-coated portion 14a.

[0117] There are two or more strips 22b of the positive current collector 22, which are arranged at equal intervals from each other. There are two or more strips 24b of the negative current collector 24, which may be arranged at equal intervals from each other. When forming a welding portion for each strip, it is desirable to arrange the strips at equal intervals from each other in terms of the surface that uniformly configures the current path from each electrode tab.

[0118] The shape and number of the strips can be various. The number of strips 22b of the positive current collector 22 may be less than the number of strips 24b of the negative current collector 24. For example, if the number of strips 24b of the negative current collector 24 is M, the number of strips 22b of the positive current collector 22 can be from 1 to M - 1 (M is a natural number of 2 or more). FIG. 5 shows a case where there are 3 strips 22b of the positive current collector 22 and 4 strips 24b of the negative current collector 24. If the strips are arranged at equal intervals from each other, the strips 22b of the positive current collector 22 in FIG. 5 can be arranged in a Y shape. The strips 24b of the negative current collector 24 can be arranged in a cross shape.

[0119] One welding portion can be formed for each strip. When the number of strips 22b of the positive current collector 22 is less than the number of strips 24b of the negative current collector 24, if the area of one positive welding portion 22a is not larger than the area of one negative welding portion 24a, the bonding area S1 between the positive non-coated portion 12a and the positive current collector 22 and the bonding area S2 between the negative non-coated portion 14a and the negative current collector 24 can be made to satisfy the relationship S1 < S2.

[0120] Figures 6 to 8 show modified examples of Fig. 5. In Fig. 6, the number of strips 22b of the positive electrode current collector plate 22 is four, and the number of strips 24b of the negative electrode current collector plate 24 is six. Fig. 7 shows a case where the number of strips 22b of the positive electrode current collector plate 22 is two and the number of strips 24b of the negative electrode current collector plate 24 is four. Fig. 8 shows a case where the number of strips 22b of the positive electrode current collector plate 22 is two and the number of strips 24b of the negative electrode current collector plate 24 is three.

[0121] In the above-described embodiments, the area of one welding portion in each current collector plate is the same, but the number of welding portions formed on the positive electrode current collector plate 22 is reduced so that the bonding area S1 between the positive electrode non-coated portion 12a and the positive electrode current collector plate 22 is smaller than the bonding area S2 between the negative electrode non-coated portion 14a and the negative electrode current collector plate 24.

[0122] In another example for making the bonding area S1 between the positive electrode non-coated portion 12a and the positive electrode current collector plate 22 smaller than the bonding area S2 between the negative electrode non-coated portion 14a and the negative electrode current collector plate 24, the number of welding portions in each current collector plate is the same, but it is also possible to make the area of one welding portion formed on the positive electrode current collector plate 22 smaller than the area of one welding portion formed on the negative electrode current collector plate 24. However, when the area of one welding portion becomes small, there may be a contact risk. Therefore, it is desirable to make the area of one welding portion in each of the current collector plates 22 and 24 the same as much as possible and adjust the number thereof.

[0123] Fig. 9 is a view showing a positive electrode current collector plate and a negative electrode current collector plate according to another embodiment of the present invention.

[0124] Referring to Fig. 9, the number of positive electrode welding portions 22a formed between the positive electrode non-coated portion (12a in Fig. 2) and the positive electrode current collector plate 22 is the same as the number of negative electrode welding portions 24a formed between the negative electrode non-coated portion (14a in Fig. 2) and the negative electrode current collector plate 24, but the size of one positive electrode welding portion 22a is smaller than the size of one negative electrode welding portion 24a, satisfying the relationship of S1 < S2. Also at this time, the positive electrode welding portion 22a and the negative electrode welding portion 24a are formed extending in the radial direction of the electrode assembly 10.

[0125] In this way, it is possible to embody various current collectors by varying the number of welding portions formed on each current collector or the area of one welding portion, or by varying the form of each electrode plate. For example, each electrode plate can be designed to include strips, and while changing the number of strips, the number of welding portions formed on one strip, etc., it is possible to control the movement speed of lithium ions by satisfying the condition that the bonding area S1 between the non-coated portion of the positive electrode and the positive current collector is smaller than the bonding area S2 between the non-coated portion of the negative electrode and the negative current collector. Further, by considering the resistance of the positive electrode active material and the negative electrode active material, etc., and having an appropriate ratio S1 / S2 of the bonding areas of the positive current collector and the negative current collector, the kinetic balance between the positive electrode and the negative electrode can be more accurately adjusted.

[0126] Applying the same welding process to the positive electrode and the negative electrode is desirable in terms of process management. Therefore, one welding portion with the same area is formed for each strip. The number of strips 24b of the negative current collector 24 is M, and the number of strips 22b of the positive current collector 22 is set from 1 to M - 1 (M is a natural number of 2 or more), so that the relationship between the bonding area S1 between the non-coated portion 12a of the positive electrode and the positive current collector 22 and the bonding area S2 between the non-coated portion 14a of the negative electrode and the negative current collector 24 is S1 < S2. Then, an appropriate ratio S1 / S2 of the bonding areas of the positive current collector and the negative current collector can be adjusted within the range from 1 / M to (M - 1) / M. And the appropriate ratio S1 / S2 of the bonding areas of the positive current collector and the negative current collector can be determined by considering all aspects of the welding strength and resistance depending on the number of welding portions.

[0127] Figures 6 to 8 are modified examples of Figure 5. In Figure 6, the number of strips 22b of the positive current collector 22 is 4, and the number of strips 24b of the negative current collector 24 is 6. Figure 7 shows the case where the number of strips 22b of the positive current collector 22 is two and the number of strips 24b of the negative current collector 24 is 4. Figure 8 shows the case where the number of strips 22b of the positive current collector 22 is two and the number of strips 24b of the negative current collector 24 is 3.

[0128] From the perspective of efficiently deriving and introducing current and reducing internal resistance, it is desirable that the bonding areas S1 and S2 are as large as possible. Conventionally, due to the emphasis on minimizing resistance, only the welding area was increased, without considering the individual characteristics of the positive and negative current collectors. The present invention is highly significant in that it adjusts the kinetic balance between the positive and negative electrodes by ensuring that the bonding areas S1 and S2 have appropriate values in terms of current derivation / introduction and internal resistance, while also ensuring that S1 < S2 within such value ranges.

[0129] On the other hand, the current path has the characteristic of flowing through a low-resistance path. The high C-rate current path during rapid charging is closely related to the number of joints between the current collector and the non-coated part, i.e., the number of welding parts. Accordingly, the inventor proposes that it is more desirable from the perspective of ease of rapid charging when reducing the number of positive electrode welding parts while ensuring S1 < S2.

[0130] As described above, in the case of the structures of the positive and negative current collectors of the comparative example shown in Fig. 3, the number of welds is the same, four each for the positive and negative current collectors. On the other hand, in the case of the positive and negative current collectors according to an embodiment of the present invention shown in Fig. 4, three welding parts are formed on the positive current collector and four on the negative current collector. The case of Fig. 4 is desirable from the perspective of rapid charging.

[0131] Thus, in the embodiments of the present invention, the kinetic balance between the positive and negative electrodes can be achieved by adjusting the bonding area with the non-coated part in each current collector. The bonding area S1 in the positive current collector is smaller than the bonding area S2 in the negative current collector. By maintaining the same types and contents of active materials, conductive materials, and binders as in the prior art and causing an increase in resistance due to a decrease in the contact area in the positive electrode, a bottleneck phenomenon in electron transfer occurs, thereby reducing the movement speed of lithium ions, and improving the kinetic balance between the positive and negative electrodes can be achieved.

[0132] As described above, according to the present invention, the kinetic balance of lithium ions is adjusted by controlling the bonding area between the non-coated portion of the jelly-roll type electrode assembly and the current collector plate without adjusting the chemistry of the positive and negative electrodes, thereby making it possible to adjust the lithium ion migration speed over a larger range. That is, by applying a differential structure in consideration of the individual characteristics of each current collector plate, such as by making the number of welds in the positive and negative current collector plates different, the characteristics of a cylindrical secondary battery including the same can be improved.

[0133] In this way, the present invention does not require the adjustment of the chemical balance between the positive and negative electrodes, and can control the lithium ion migration speed in a wider range than the method of adjusting the chemical balance. It is possible to provide a cylindrical secondary battery that can adjust the lithium ion migration speed, can be easily fast-charged, and has excellent cycle characteristics, within the limit of the process implementation capability according to the composition of the active material layer, i.e., while maintaining the existing process window.

[0134] Fig. 10 is a perspective view of a cylindrical secondary battery according to another embodiment of the present invention, and Fig. 11 is a vertical cross-sectional view of the cylindrical secondary battery of Fig. 10.

[0135] 10 and 11, the cylindrical secondary battery 100 includes an electrode assembly 10, a positive current collector 120, and a negative current collector 140. The cylindrical secondary battery 100 may further include a battery can 110, a rivet terminal 130, an insulator 150, an insulating gasket 160, a cap plate 170, a sealing gasket 180, etc.

[0136] The battery can 110 is substantially cylindrical. The battery can 110 has an opening formed on one side, in this embodiment, at the bottom end, and is made of a conductive material such as metal. The opposite side of the opening in the battery can 110 is a closed portion. The material of the battery can 110 may be, for example, aluminum, steel, or stainless steel. The side (outer periphery) and top of the battery can 110 may be integrally formed. The top of the battery can 110 (a surface parallel to the XY plane) has a substantially flat shape. The battery can 110 receives the electrode assembly 10 from the opening, and also receives an electrolyte.

[0137] 1, the positive electrode uncoated portion 12a and the negative electrode uncoated portion 14a extend in opposite directions along the height direction (parallel to the Z axis) of the cylindrical secondary battery 100. The positive electrode uncoated portion 12a extends toward the closed portion of the battery can 110, and the negative electrode uncoated portion 14a extends toward the open portion of the battery can 110. A cavity H1 is formed in the center of the winding of the electrode assembly 10.

[0138] The battery can 110 is electrically connected to the electrode assembly 10. The battery can 110 is electrically connected to, for example, the negative electrode uncoated portion 14a of the electrode assembly 10. This allows the battery can 110 to have the same polarity as the negative electrode uncoated portion 14a. The entire surface of the battery can 110 can function as a negative electrode terminal.

[0139] The rivet terminal 130 may be made of a conductive metal material. The rivet terminal 130 may be provided, for example, in a through hole formed in the center of the closure of the battery can 110. A part of the rivet terminal 130 may be exposed to the top of the battery can 110, and the remaining part may be located inside the battery can 110. The rivet terminal 130 may be fixed onto the inner surface of the closure of the battery can 110 by, for example, riveting.

[0140] The insulator 150 is interposed between the closure of the battery can 110 and the positive current collector plate 120. The rivet terminal 130 may penetrate the insulator 150 and be coupled to and electrically connected to the positive non-coated portion 12a of the positive plate 12 of the electrode assembly 10. In this case, the rivet terminal 130 may have a positive electrode. As a result, the rivet terminal 130 has a polarity opposite to that of the battery can 110 and may be used as a positive terminal.

[0141] When the rivet terminal 130 has a positive polarity as described above, the rivet terminal 130 is provided so as to be electrically insulated from the battery can 110 having a negative polarity. Electrical insulation between the rivet terminal 130 and the battery can 110 can be achieved in various ways. For example, insulation can be achieved by interposing an insulating gasket 160 between the rivet terminal 130 and the battery can 110. Alternatively, insulation can be achieved by forming an insulating coating layer on a part of the rivet terminal 130. Alternatively, a method can be applied in which the rivet terminal 130 is structurally and firmly fixed so that contact between the rivet terminal 130 and the battery can 110 is not possible. Alternatively, a combination of the above-mentioned methods can be used.

[0142] In this way, the cylindrical secondary battery 100 has a structure in which the rivet terminal 130 and the remaining areas on the top surface of the battery can 110, excluding the area occupied by the rivet terminal 130, can be used as a positive electrode terminal and a negative electrode terminal, respectively. As a result, when electrically connecting a plurality of cylindrical secondary batteries 100, the cylindrical secondary battery 100 can simplify the electrical connection structure because the positive and negative electrodes are both connected in one direction. In addition, the cylindrical secondary battery 100 has a structure in which most of the surface opposite the open part of the battery can 110 can be used as a negative electrode terminal, which is an advantage in that a sufficient area can be secured for welding parts for electrical connection.

[0143] 11, the battery can 110 may have a beading portion 112 and a crimping portion 114 formed at its lower end. The beading portion 112 is located at the lower portion of the electrode assembly 10. The beading portion 112 is formed by pressing around the outer circumferential surface of the battery can 110. The beading portion 112 prevents the electrode assembly 10, which has a size approximately corresponding to the inner diameter of the battery can 110, from slipping out of an opening formed at the lower end of the battery can 110, and may function as a support portion on which a cap plate 170 is provided.

[0144] The crimping portion 114 is formed on the side facing the opening of the battery can 110 relative to the beading portion 112. In this embodiment, the crimping portion 114 is formed below the beading portion 112. The crimping portion 114 has a bent shape extending toward the opening of the battery can 110 so as to cover the outer peripheral surface of the cap plate 170 disposed below the beading portion 112 and a part of the lower surface of the cap plate 170.

[0145] However, the present invention does not exclude the case where the battery can 110 does not include such a beading portion 112 and / or crimping portion 114. That is, in the present invention, when the battery can 110 does not include the beading portion 112 and / or the crimping portion 114, the fixing of the electrode assembly 10 and / or the sealing of the battery can 110 may be achieved, for example, by additionally applying a component that can function as a stopper for the electrode assembly 10. Also, when the cylindrical secondary battery 100 includes a cap plate 170, the fixing of the electrode assembly 10 and / or the sealing of the battery can 110 may be achieved, for example, by additionally applying a structure to which the cap plate 170 can be attached and / or by welding the battery can 110 and the cap plate 170. That is, the cap plate 170 may seal the open portion of the battery can 110. For example, the present applicant's Korean Patent Publication KR10-2019-0030016A discloses a cylindrical battery cell in which a beading portion is omitted, and such a structure may also be adopted in the present invention.

[0146] 11, the cap plate 170 may be made of, for example, a metal material to ensure rigidity. The cap plate 170 may cover the open portion of the battery can 110. That is, the cap plate 170 forms the lower surface of the cylindrical secondary battery 100. Even if the cap plate 170 is made of a conductive metal material, it does not have polarity. The absence of polarity may mean that the cap plate 170 is not connected to the electrode assembly 10. It may also mean that the cap plate 170 is electrically insulated from the battery can 110 and the rivet terminal 130. Since it does not have polarity, the cap plate 170 does not function as a positive electrode terminal or a negative electrode terminal. The cap plate 170 may not be electrically connected to the electrode assembly 10 and the battery can 110, and the material thereof does not necessarily have to be a conductive metal.

[0147] When the battery can 110 includes a beading portion 112, the cap plate 170 may be provided on the beading portion 112 formed on the battery can 110. When the battery can 110 includes a crimping portion 114, the cap plate 170 may be fixed by the crimping portion 114. A sealing gasket 180 may be interposed between the cap plate 170 and the crimping portion 114 of the battery can 110 to ensure airtightness of the battery can 110.

[0148] The cap plate 170 may further include a vent portion 190 formed to prevent the internal pressure from increasing beyond a preset value due to gas generated inside the battery can 110. The vent portion 190 is a region of the cap plate 170 having a thickness thinner than the surrounding region. The vent portion 190 is structurally weaker than the surrounding region. Thus, when an abnormality occurs in the cylindrical secondary battery 100 and the internal pressure of the battery can 110 increases above a certain level, the vent portion 190 is detected and the gas generated inside the battery can 110 is discharged. The vent portion 190 may be formed, for example, by notching one or both sides of the cap plate 170 to partially reduce the thickness of the battery can 110.

[0149] The positive current collector 120 is coupled to the upper part of the electrode assembly 10. The positive current collector 120 is made of a conductive metal material and is connected by being joined to the positive non-coated portion 12a by welding. The negative current collector 140 is coupled to the lower part of the electrode assembly 10. The negative current collector 140 is made of a conductive metal material and is connected by being joined to the negative non-coated portion 14a by welding. The peripheral region of the negative current collector 140 can be interposed and fixed between the inner surface of the battery can 110 and the sealing gasket 180. In this case, the negative current collector 140 can be welded onto the mounting surface formed by the beading portion 112 of the battery can 110.

[0150] In such a cylindrical secondary battery 100, the bonding area S1 between the positive non-coated portion 12a and the positive current collector 120 is smaller than the bonding area S2 between the negative non-coated portion 14a and the negative current collector 140. The advantages on the kinetic balance surface when the relationship S1 < S2 is satisfied are as described above. The positive current collector 120 and the negative current collector 140 in various embodiments satisfying the relationship S1 < S2 will be described later.

[0151] The cylindrical secondary battery 100 can be, for example, a cylindrical secondary battery in which the form factor ratio (the value obtained by dividing the diameter of the cylindrical battery by the height, that is, the ratio of the diameter Φ to the height H) is greater than about 0.4. Such a secondary battery is suitable for, for example, a high-output and large-capacity secondary battery for a hybrid vehicle.

[0152] Here, the form factor means a value indicating the diameter and height of the cylindrical secondary battery. The cylindrical secondary battery 100 can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the last digit 0 indicates that the cross-section of the cell is circular.

[0153] The cylindrical secondary battery 100 may have a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418. The cylindrical secondary battery 100 may have a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640. The cylindrical secondary battery 100 may have a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.436. The cylindrical secondary battery 100 may have a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600. The cylindrical secondary battery 100 may have a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0154] Conventionally, secondary batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of an 18650 cell, its diameter is about 18 mm, its height is about 65 mm, and its form factor ratio is about 0.277. In the case of a 21700 cell, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is about 0.300.

[0155] Fig. 12 is a view for explaining an electrode assembly included in a cylindrical secondary battery according to another embodiment of the present invention. In the above description with reference to Fig. 2, it was mentioned that each of the non-coated portions 12a, 14a of the electrode assembly 10 in Fig. 1 may be bent toward the winding center C of the electrode assembly 10. Fig. 12 shows a preferable example of an electrode assembly to which such a bend is applied.

[0156] 12, at least a portion of the positive electrode non-coated portion 12a of the positive electrode plate 12 of the electrode assembly 10' is divided into a plurality of segment pieces 12c. The segment pieces 12c may be notched in a direction along a short side of the positive electrode current collector of the positive electrode plate 12. For example, the segment pieces 12c may be notched by a laser. Alternatively, the segment pieces 12c may be formed by a known metal foil cutting process such as ultrasonic cutting or punching. Each of the plurality of segment pieces 12c may have a rectangular, trapezoidal, triangular, parallelogram, semicircular, or inverse elliptical structure.

[0157] The positive electrode non-coated portion 12a may include a core-side non-coated portion adjacent to the winding center of the electrode assembly 10', an outer peripheral side non-coated portion adjacent to the outer peripheral side of the electrode assembly 10', and an intermediate non-coated portion interposed between the core-side non-coated portion and the outer peripheral side non-coated portion, and the segment piece 12c may be formed in the intermediate non-coated portion. The core-side non-coated portion and the outer peripheral side non-coated portion may not have segment pieces formed therein. The height (length in the Z-axis direction) of the positive electrode non-coated portion 12a is not constant and may have a relative difference in the winding direction. For example, the height of the outer peripheral side non-coated portion may be relatively smaller than the core-side non-coated portion and the intermediate non-coated portion. The height of the intermediate non-coated portion may have a step shape that increases stepwise from the core side to the outer peripheral side. The width (length in the X direction) of the core-side non-coated portion may be designed under the condition that the cavity H1 of the electrode assembly 10' is not blocked when the segment piece 12c of the intermediate non-coated portion is bent toward the core side. In this manner, by forming segment piece 12c while adjusting the height and length of the other non-coated portion sections where segment piece 12c is not formed, the cavity H1 of the electrode assembly 10' can be prevented from being blocked when the positive electrode non-coated portion 12a is bent, and the electrolyte injection process and the welding process can be easily performed.

[0158] The plurality of segment pieces 12c may be folded toward the core side of the electrode assembly 10'. In this case, the plurality of segment pieces 12c may be overlapped in multiple layers along the radial direction of the electrode assembly 10'. When the plurality of segment pieces 12c are formed and folded in this manner, there is no risk of the non-coated portion not being folded properly, as compared to the case where the non-coated portion is not folded properly. If the non-coated portion is not folded properly, the separation film is exposed between the non-coated portions, which may cause a problem that the separation film is damaged by a high-energy laser during laser welding.

[0159] Meanwhile, at least a portion of the negative electrode uncoated portion 14a may also be divided into a plurality of segments. All of the details relating to the segments and folding of the negative electrode uncoated portion 14a are applicable to the positive electrode uncoated portion 12a.

[0160] FIG. 13 is a vertical sectional view of a cylindrical secondary battery including the electrode assembly of FIG.

[0161] 13, a cylindrical secondary battery 100' is the same as the cylindrical secondary battery 100 of FIG 11, except that it includes the electrode assembly 10' of FIG 12. The only difference is that the cylindrical secondary battery 100' has a negative current collector hole at the center of the negative current collector 140, designated by reference symbol H2.

[0162] In this cylindrical secondary battery 100', the positive electrode uncoated portion 12a and the negative electrode uncoated portion 14a have a folded shape. This reduces the space occupied by each of the uncoated portions 12a, 14a, improving the energy density. In addition, the bonding area between each of the uncoated portions 12a, 14a and each of the current collector plates 120, 140 is increased, improving the bonding force and reducing resistance.

[0163] Hereinafter, various embodiments of the positive current collector 120 and the negative current collector 140 will be described. In the cylindrical secondary batteries 100 and 100', the bonding area S1 between the non-coated positive electrode portion 12a and the positive current collector 120 is smaller than the bonding area S2 between the non-coated negative electrode portion 14a and the negative current collector 140. When the relationship S1 < S2 is satisfied, the kinetic balance between the positive electrode and the negative electrode can be adjusted. The positive current collector 120 and the negative current collector 140 described below satisfy the relationship S1 < S2.

[0164] First, FIGS. 14 to 17 are diagrams showing various forms of the positive current collector.

[0165] Referring to FIGS. 14 to 17, the positive current collector 120 includes a peripheral portion 121, a positive tab coupling portion 122, and a terminal coupling portion 123. The peripheral portion 121, the positive tab coupling portion 122, and the terminal coupling portion 123 can all be on the same plane. That is, the positive current collector 120 is a substantially plate-like member having a thickness smaller than the horizontal or vertical length of the portion having a large area, and when the portion having a large area in the positive current collector 120 is placed on the upper end of the electrode assembly 10, 10', the entire positive current collector 120 has a shape extending parallel to the upper end surface of the electrode assembly 10, 10'. In the positive current collector 120, there is no height difference among the peripheral portion 121, the positive tab coupling portion 122, and the terminal coupling portion 123. Such a planar structure does not occupy much volume in the battery can 110, so the space utilization is high.

[0166] The peripheral portion 121 can have a substantially rim form in which a space S is formed in at least a part of the inner region. In the drawings, only the case where the peripheral portion 121 has a substantially circular rim form is shown, but the present invention is not limited thereto. The peripheral portion 121 can have a substantially square rim form or other forms different from those shown.

[0167] The positive electrode tab coupling portion 122 extends inward from the peripheral portion 121 and is coupled to the positive electrode non-coated portion 12a by welding. The positive electrode tab coupling portion 122 may also be referred to as a strip as described with reference to FIG. 5. The terminal coupling portion 123 is located inside the peripheral portion 121 and spaced apart from the positive electrode tab coupling portion 122. The terminal coupling portion 123 may be coupled to the above-mentioned rivet terminal 130 by welding. The terminal coupling portion 123 may be located, for example, in the center of the inner space of the peripheral portion 121. The terminal coupling portion 123 may be disposed at a position corresponding to a cavity H1 formed in the winding center of the electrode assembly 10, 10'.

[0168] The positive electrode tab coupling part 122 and the terminal coupling part 123 are not directly connected to each other, but are spaced apart from each other and are electrically connected to each other through the peripheral part 121. In this manner, the positive electrode current collector plate 120 has a structure in which the positive electrode tab coupling part 122 and the terminal coupling part 123 are not directly connected to each other, but are connected to each other through the peripheral part 121, so that when an impact and / or vibration occurs to the cylindrical secondary battery 100, 100', the impact applied to the coupling part of the positive electrode tab coupling part 122 and the positive electrode non-coated part 12a and the coupling part of the terminal coupling part 123 and the rivet terminal 130 can be dispersed. As a result, the positive electrode current collector plate 120 has an effect of minimizing or preventing damage to the welded part due to an external impact. In addition, the positive current collector 120 has a structure in which stress is concentrated at the connection portion between the peripheral portion 121 and the terminal coupling portion 123 when an external impact is applied, but since this connection portion is not a portion where a weld is formed for coupling the components, it is possible to prevent product defects caused by damage to the weld due to external impact. As such, the positive current collector 120 has a structure in which force is not concentrated at the coupling portion between the components even when an external impact and / or vibration is applied during use, and therefore the performance of the cylindrical secondary battery 100, 100' including the same is improved.

[0169] The positive electrode current collector plate 120 may further include a connecting portion 124 extending inward from the peripheral portion 121 and connected to the terminal coupling portion 123. At least a portion of the connecting portion 124 may be formed to have a smaller width than the positive electrode tab coupling portion 122. In this case, when a current flows through the connecting portion 124 due to an increase in electrical resistance, a larger resistance occurs than in other portions. As a result, when an overcurrent occurs, a portion of the connecting portion 124 breaks, thereby enabling the overcurrent to be cut off. The width of the connecting portion 124 may be adjusted to an appropriate level in consideration of such an overcurrent cut-off function. At least a portion of the connecting portion 124 may have a relatively narrow width to enhance the current cut-off function.

[0170] The connecting portion 124 may include a tapered portion 124a whose width gradually narrows along a direction from the inner surface of the peripheral portion 121 toward the terminal coupling portion 123. When the tapered portion 124a is included, the rigidity of the part at the connection portion between the connecting portion 124 and the peripheral portion 121 may be improved.

[0171] The positive current collector plate 120 may include a plurality of positive electrode tab coupling portions 122. The plurality of positive electrode tab coupling portions 122 may be arranged at equal intervals from one another along the circumferential direction. The extension lengths of the plurality of positive electrode tab coupling portions 122 may be the same as one another. The terminal coupling portion 123 may be arranged to be surrounded by the plurality of positive electrode tab coupling portions 122. The connecting portion 124 may be located between a pair of adjacent positive electrode tab coupling portions 122. In this case, the distance from the connecting portion 124 to any one of the pair of positive electrode tab coupling portions 122 along the peripheral portion 121 may be the same as the distance from the connecting portion 124 to the remaining one of the pair of positive electrode tab coupling portions 122 along the peripheral portion 121.

[0172] There may be a plurality of connecting portions 124. Each of the plurality of connecting portions 124 may be disposed between a pair of adjacent positive electrode tab bonding portions 122. The plurality of connecting portions 124 may be disposed at equal intervals from one another along the circumferential direction.

[0173] As described above, in the case where a plurality of positive electrode tab binding parts 122 and / or connecting parts 124 are included, if the distance between the positive electrode tab binding parts 122 and / or the distance between the connecting parts 124 and / or the distance between the positive electrode tab binding parts 122 and the connecting parts 124 are constant, a current flow from the positive electrode tab binding parts 122 to the connecting parts 124 or from the connecting parts 124 to the positive electrode tab binding parts 122 may be smoothly formed.

[0174] The positive electrode tab coupling portion 122 may be welded to a certain region in a state where it is provided on a bent surface of the positive electrode uncoated portion 12a in the electrode assembly 10'. That is, the positive electrode tab coupling portion 122 may be coupled to a region where a plurality of segment pieces (12c in FIG. 12) are overlapped. A positive electrode weld may be formed for each positive electrode tab coupling portion 122. A coupling area S1 between the positive electrode uncoated portion 12a and the positive electrode current collector plate 120 is secured by the positive electrode weld at the positive electrode tab coupling portion 122. The positive electrode weld may be formed to extend along the extension direction of the positive electrode tab coupling portion 122.

[0175] 14, 15, and 17, the number of positive electrode tab coupling parts 122 is four, and in Fig. 16, the number of positive electrode tab coupling parts 122 is three. The number of positive electrode tab coupling parts 122 may vary, and the coupling area S1 between the positive electrode non-coated part 12a and the positive electrode current collector plate 120 may be changed by adjusting the number of positive electrode tab coupling parts 122 and the number and area of ​​the positive electrode welding parts.

[0176] 18 to 25 are diagrams showing various forms of the negative electrode current collector plate.

[0177] 18 to 21, the negative electrode current collector 140 includes at least one negative electrode tab coupling part 142 coupled to the negative electrode non-coated part 14a, and at least one can coupling part 143 extending from the negative electrode tab coupling part 142 and electrically coupled to the beading part 112 on the inner surface of the battery can 110. The negative electrode tab coupling part 142 and the can coupling part 143 do not have to be located on the same plane. That is, the negative electrode current collector 140 is a substantially plate-shaped member having a thickness smaller than the width or length of a part having a large area, and when the part having a large area of ​​the negative electrode current collector 140 is provided at the lower end of the electrode assembly 10, 10', there is a height difference between the negative electrode tab coupling part 142 and the can coupling part 143 of the negative electrode current collector 140. This three-dimensional structure ensures a sufficient contact area between the negative electrode tab coupling portion 142 and the negative electrode non-coated portion 14a, while the can coupling portion 143 is raised upward and fixed to the beading portion 112 of the battery can 110, thereby improving the bonding strength of the coupling portion with the battery can 110.

[0178] The center portion 141 of the negative electrode current collector 140 may be substantially disk-shaped. The center portion 141 may be selectively coupled to the negative electrode non-coated portion 14a. The center portion 141 may be a ring-shaped plate having a negative electrode current collector hole H2 at its center.

[0179] The negative current collector hole H2 is formed at a position corresponding to the cavity H1 of the electrode assembly 10, 10' and may be circular. The cavity H1 and the negative current collector hole H2, which are in communication with each other, may function as a passage for inserting a welding rod for welding the rivet terminal 130 and the positive current collector plate 120 or for irradiating a laser welding beam.

[0180] The diameter of the negative current collector hole H2 may be the same as or larger than the diameter of the cavity H1 of the electrode assembly 10'. If the diameter of the negative current collector hole H2 is preferably set to be larger than the diameter of the cavity H1 of the electrode assembly 10', it becomes easier to secure a space by inserting a welding guide when inserting a welding rod or irradiating a laser welding beam for welding the rivet terminal 130 and the positive current collector plate 120.

[0181] The center portion 141 and the negative electrode tab coupling portion 142 are disposed in the lower portion of the electrode assembly 10, 10', and may be located above the beading portion 112 when the beading portion 112 is formed in the battery can 110.

[0182] The negative electrode current collector 140 may have at least one leg structure extending in a radial direction with the negative electrode tab coupling part 142 and the can coupling part 143 connected to each other. Preferably, a plurality of leg structures may be provided. For example, referring to Figs. 18 to 20, the negative electrode current collector 140 may have a four-leg structure. Referring to Fig. 21, the negative electrode current collector 140 may have a six-leg structure. In this case, when a plurality of leg structures are provided, a plurality of can coupling parts 143 may also be provided. In this case, although not shown, a plurality of can coupling parts 143 may be connected to each other to be integrally formed.

[0183] The negative electrode tab coupling part 142 may extend radially from the center part 141 of the negative electrode current collector plate 140 toward the side wall of the battery can 110. For example, a plurality of negative electrode tab coupling parts 142 may be provided. The plurality of negative electrode tab coupling parts 142 may be spaced apart from each other around the center part 141. The negative electrode tab coupling part 142 may also be referred to as a strip as described with reference to FIG. 5. By providing a plurality of negative electrode tab coupling parts 142, the coupling area with the negative electrode uncoated part 14a may be increased. As a result, the coupling force between the negative electrode uncoated part 14a and the negative electrode tab coupling part 142 may be secured, and electrical resistance may be reduced.

[0184] The negative electrode tab coupling part 142 may be coupled to the negative electrode uncoated part 14a by welding. The negative electrode tab coupling part 142 may be welded to a certain area in a state where it is provided on the bent surface of the negative electrode uncoated part 14a in the electrode assembly 10'. That is, the negative electrode tab coupling part 142 may be coupled to an area where a plurality of segment pieces are overlapped. A negative electrode weld part may be formed for each negative electrode tab coupling part 142. The negative electrode weld part ensures a coupling area S2 between the negative electrode uncoated part 14a and the negative electrode current collector plate 140 at the negative electrode tab coupling part 142. The negative electrode weld part may be formed extending in the extension direction of the negative electrode tab coupling part 142.

[0185] A longitudinal end of the negative electrode tab binding portion 142 may be located inside an innermost point of the beading portion 112 formed on the battery can 110. More specifically, a boundary region between the negative electrode tab binding portion 142 and the can binding portion 143 may be located more inside in a direction toward the cavity H1 of the electrode assembly 10, 10' than an innermost point of the beading portion 112 formed on the battery can 110. This structure can prevent damage to the binding portion between the components that may occur when the negative electrode current collector 140 is excessively bent in order to position the end of the can binding portion 143 at the beading portion 112.

[0186] The can coupling portion 143 may extend from an end of the negative electrode tab coupling portion 142 and be coupled to the beading portion 112 on the inner surface of the battery can 110. For example, the can coupling portion 143 may have a shape extending from an end of the negative electrode tab coupling portion 142 toward a side wall of the battery can 110. For example, a plurality of can coupling portions 143 may be provided. The plurality of can coupling portions 143 may be located spaced apart from each other along the circumference of the center portion 141. As shown in FIG. 11 and FIG. 13, the plurality of can coupling portions 143 may be coupled to the beading portion 112 on the inner surface of the battery can 110. In addition, due to the structure in which the negative electrode current collector 140 is coupled to the beading portion 112 of the battery can 110 rather than to the inner surface of the cylindrical portion of the battery can 110, the distance between the negative electrode current collector 140 and the beading portion 112 may be reduced. This minimizes the dead space inside the battery can 110, improving the energy density of the cylindrical secondary batteries 100, 100'.

[0187] The can joint 143 may be pressed and fixed by the crimping portion 114 of the battery can 110. The can joint 143 may include a contact portion 143a that is joined to the beading portion 112 on the inner surface of the battery can 110, and a connecting portion 143b that connects between the negative electrode tab joint 142 and the contact portion 143a.

[0188] The contact portion 143a is bonded to the inner surface of the battery can 110. In the case where the beading portion 112 is formed on the battery can 110, the contact portion 143a may be bonded to the beading portion 112. In this case, as described above, for stable contact and bonding, the beading portion 112 and the contact portion 143a may have a shape extending in a direction substantially parallel to the bottom surface of the battery can 110, i.e., in a direction substantially perpendicular to the side wall of the battery can 110. That is, the contact portion 143a includes at least a part of a flat portion substantially parallel to the bottom surface of the battery can 110.

[0189] As shown in FIG. 18, the connecting portion 143b may have at least one bent portion B in which the extension direction is changed at least once between the center portion 141 and the contact portion 143a. That is, the connecting portion 143b may have, for example, a spring-like structure or a bellows-like structure capable of contracting and expanding within a certain range. Meanwhile, the connecting portion 143b may be elastically biased upward by the bent portion B. This structure of the connecting portion 143b allows the contact portion 143a to be in close contact with the beading portion 112 during the process of housing the electrode assemblies 10, 10' to which the negative electrode current collector plate 140 is connected into the battery can 110 even if there is a variation in height of the electrode assemblies 10, 10' within a certain range. In addition, according to this structure of the connecting portion 143b, a shape may be more stably realized during a sizing process. The sizing process is a compression process for reducing the height occupied by the region of the beading portion 112 of the battery can 110 in order to reduce the total height of the cylindrical secondary batteries 100, 100' when manufacturing the cylindrical secondary batteries 100, 100'. In addition, the contractible and expandable structure of the connecting portion 143b reduces the impact caused by the movement of the electrode assemblies 10, 10' within a certain range even if the electrode assemblies 10, 10' move up and down due to vibration and / or impact generated during use of the cylindrical secondary batteries 100, 100'.

[0190] The contact portion 143a and the connecting portion 143b may have various shapes. The negative current collector plate 140 of Fig. 18 and the negative current collector plate 140 of Fig. 19 differ only in the shape of the contact portion 143a, and the structure of the negative current collector plate 140 described above may be substantially the same otherwise.

[0191] 19, the contact portion 143a may have a shape in which at least a portion extends along the inner circumferential surface of the battery can 110. For example, the contact portion 143a may have an arc shape extending along the beading portion of the battery can 110. Also, although not shown, in order to maximize the contact area, the negative electrode current collector 140 may be configured such that the sum of the extension lengths of the contact portions 143a of at least one can coupling portion 143 is substantially equal to the inner circumference of the battery can 110. In such an embodiment, the effect of improving the coupling force and reducing the electrical resistance by maximizing the coupling area may be achieved.

[0192] Next, referring to FIG. 20, the negative electrode collector plate 140 of FIG. 20 differs from the negative electrode collector plate 140 of FIG. 19 only in the shape of the contact portion 143a and the connecting portion 143b, and otherwise the structure of the negative electrode collector plate 140 described above can be substantially applied.

[0193] 20, the connecting portion 143b may have a shape in which at least a portion extends along the inner circumferential surface of the battery can 110. Specifically, the contact portion 143a may be an arc extending along the beading portion of the battery can 110, and the connecting portion 143b may be an arc extending along the contact portion 143a. With this structure, the area of ​​the negative current collector 140 is further increased compared to the negative current collector 140 shown in FIG. 19, thereby maximizing the effect of reducing electrical resistance.

[0194] As shown in Figs. 18, 19 and 21, the connecting portion between the contact portion 143a and the connecting portion 143b may be bent. Alternatively, as shown in Fig. 20, the connecting portion between the contact portion 143a and the connecting portion 143b may have a shape complementary to the inner surface of the beading portion 112. In particular, the connecting portion between the contact portion 143a and the connecting portion 143b may have a shape that matches the inner surface of the beading portion 112 and may be coupled to the beading portion 112 without any gaps. This structure allows the beading portion 112 to effectively support the negative electrode current collector plate 140. In addition, this structure prevents unnecessary interference between the beading portion 112 and the connecting portion 143b. Therefore, the stable coupling between the contact portion 143a and the beading portion 112 can be effectively maintained.

[0195] Meanwhile, referring to Fig. 20, the negative current collector plate 140 may not have a bent portion B, unlike the negative current collector plate 140 shown in Figs. 18, 19, and 21. When the bent portion B is not provided, the amount of raw material required to manufacture the negative current collector plate 140 can be reduced, and thus the manufacturing cost of the negative current collector plate 140 can be reduced.

[0196] Meanwhile, the contact portion 143a may be interposed and fixed between the beading portion 112 of the battery can 110 and the sealing gasket 180. That is, in a state in which the contact portion 143a is interposed between the beading portion 112 of the battery can 110 and the sealing gasket 180, the contact portion 143a may be fixed by the crimping force of the crimping portion 114.

[0197] According to an embodiment of the present invention, the circumferential length of the contact portion 143a may be the same as the circumferential length of the negative electrode tab coupling portion 142. In addition, the circumferential length of the contact portion 143a may be the same as the circumferential length of the connecting portion 143b. For example, referring to FIGS. 18 and 21, it can be seen that the negative electrode tab coupling portion 142, the connecting portion 143b, and the contact portion 143a extend with the same width.

[0198] According to another embodiment of the present invention, the circumferential length of the contact portion 143a may be formed relatively longer than the circumferential length of the negative electrode tab coupling portion 142. Also, preferably, the circumferential length of the contact portion 143a may be formed relatively longer than the circumferential length of the connecting portion 143b. For example, referring to FIG. 19 and FIG. 20, it can be seen that the circumferential length of the contact portion 143a is formed relatively longer than the circumferential length of the negative electrode tab coupling portion 142. Also, referring to FIG. 19, it can be seen that the circumferential length of the contact portion 143a is formed relatively longer than the circumferential length of the connecting portion 143b. By forming the circumferential length of the contact portion 143a to be longer in this manner, it is possible to improve the bonding force with the beading portion 112 of the negative electrode current collector plate 140. Furthermore, by forming the circumferential length of the contact portion 143a and / or the connecting portion 143b to be longer, it is possible to reduce the internal resistance of the battery.

[0199] 18 to 20, the number of negative electrode tab coupling parts 142 is four, and in Fig. 21, the number of negative electrode tab coupling parts 142 is six. The number of negative electrode tab coupling parts 142 in the negative electrode current collector plate 140 may vary, and the coupling area S2 between the negative electrode uncoated part 14a and the negative electrode tab coupling part 142 may be changed by adjusting the number of the negative electrode tab coupling parts 142 and the number and area of ​​the negative electrode welding parts.

[0200] The cylindrical secondary batteries 100, 100' can be realized by various combinations of the positive electrode current collector plates 120 shown in Figs. 14 to 17 and the negative electrode current collector plates 140 shown in Figs. 18 to 21.

[0201] By making the area of ​​each welded portion the same for each current collector plate and reducing the number of welded portions formed on the positive current collector plate 120, the bonding area S1 between the positive non-coated portion 12a and the positive current collector plate 120 can be made smaller than the bonding area S2 between the negative non-coated portion 14a and the negative current collector plate 140. When a positive welded portion is formed for each positive tab coupling portion 122 and a negative welded portion is formed for each negative tab coupling portion 142, this condition can be met by making the number of positive tab coupling portions 122 smaller than the number of negative tab coupling portions 142. As a result, the number of negative electrode tab binding portions 142 of the negative electrode current collector 140 can be M, and the number of positive electrode tab binding portions 122 of the positive electrode current collector 120 can be 1 to M-1 (M is a natural number equal to or greater than 2). In this case, the appropriate bonding area ratio (S1 / S2) of the positive electrode current collector and the negative electrode current collector can be adjusted within the range of 1 / M to (M-1) / M.

[0202] The welding process for the positive current collector plate 120 and the welding process for the negative current collector plate 140 can be applied with the same set of conditions such as laser output, irradiation time, irradiation speed, etc., and applying them in the same manner makes it easier to manage the process than if they were not applied. In such a case, the area of ​​one positive electrode weld and the area of ​​one negative electrode weld are formed to be the same. Therefore, it is a preferred embodiment to adjust the welding area by adjusting the number of positive electrode welds and the number of negative electrode welds while applying the same conditions to the welding process for the positive current collector plate 120 and the welding process for the negative current collector plate 140. It is also preferred in terms of resistance to form a positive electrode weld for each positive electrode tab binding portion 122 and a negative electrode weld for each negative electrode tab binding portion 142. Therefore, it is a preferred embodiment to adjust the welding area by making the number of positive electrode tab binding portions 122 less than the number of negative electrode tab binding portions 142.

[0203] For example, a combination of a positive current collector plate 120 having four positive tab binding portions 122 as shown in Figures 14 to 17 and a negative current collector plate 140 having six negative tab binding portions 142 as shown in Figure 21 may be used. In another example, a combination of a positive current collector plate 120 having three positive tab binding portions 122 as shown in Figure 16 and a negative current collector plate 140 having four negative tab binding portions 142 as shown in Figures 18 to 21 may be used.

[0204] Of course, in another example, in order to make the bonding area S1 between the positive electrode uncoated portion 12a and the positive electrode collector plate 120 smaller than the bonding area S2 between the negative electrode uncoated portion 14a and the negative electrode collector plate 140, the number of welds on each collector plate may be the same, but the area of ​​each weld formed on the positive electrode collector plate 120 may be further reduced.

[0205] Next, referring to FIGS. 22 to 25, a modified negative current collector 140 is shown as compared with the negative current collector 140 shown in FIGS.

[0206] 22, the negative electrode current collector 140 of FIG. 22 differs from the negative electrode current collector 140 of FIG. 18 in that the can coupling portion 143 extends from the negative electrode tab coupling portion 142, and the negative electrode tab coupling portion 142 and the can coupling portion 143 are not directly connected to each other. Otherwise, the structure of the negative electrode current collector 140 described above can be substantially the same.

[0207] 22, the negative electrode tab coupling part 142 and the can coupling part 143 are indirectly coupled to each other through the center part 141, and are not directly coupled to each other. This can minimize the possibility of damage occurring at the coupling part between the negative electrode collector plate 140' and the electrode assembly 10, 10' and the coupling part between the negative electrode collector plate 140' and the battery can 110 when an external impact is applied to the cylindrical secondary battery 100, 100' of the present invention.

[0208] Next, referring to Fig. 23, the negative current collector 140 of Fig. 23 differs from the negative current collector 140 described with reference to Fig. 22 only in the shape of the contact portion 143a, and otherwise the structures of the negative current collector 140 of Figs. 18 and 22 described above may be substantially the same. In addition, the contact portion 143a of the negative current collector 140 of Fig. 23 has a shape extending along the inner circumferential surface of the battery can 110, and the description thereof may be substituted for the description of the negative current collector 140 described with reference to Fig. 19.

[0209] 24, the negative electrode current collector 140 of FIG. 24 differs from the negative electrode current collector 140 described with reference to FIG. 22 only in that it further includes an additional can coupling portion 144; otherwise, the structures of the negative electrode current collector 140 of FIGS. 18 and 22 described above can be substantially the same.

[0210] The additional can coupling part 144 extends from an end of the negative electrode tab coupling part 142 and is coupled to the inner surface of the battery can 110. At least one end of the plurality of negative electrode tab coupling parts 142 is provided with such an additional can coupling part 144. The additional can coupling part 144 includes an additional contact part 144a coupled on the inner surface of the battery can 110 and an additional connection part 144b connecting the end of the negative electrode tab coupling part 142 and the additional contact part 144a.

[0211] The additional contact portion 144a is bonded to the inner surface of the battery can 110. In the case where a beading portion 112 is formed in the battery can 110, the additional contact portion 144a may be bonded to the beading portion 112 in the same manner as the contact portion 143a. Also, like the form of the contact portion 143a shown in FIG. 23, the additional contact portion 144a may also have a form in which at least a portion of the additional contact portion 144a extends along the inner circumferential surface of the battery can 110.

[0212] The additional connecting part 144b may have at least one bent part in which the extension direction is changed at least once between the negative electrode tab coupling part 142 and the additional contact part 144a, similar to the connecting part 143b described with reference to Fig. 18. The additional connecting part 144b has a structure capable of contracting and expanding due to the formation of the bent part, and thus provides advantages in the assembly process of the cylindrical secondary batteries 100, 100' and a cushioning effect, as described above.

[0213] 25, the negative electrode current collector plate 140 may have at least one liquid injection hole H3. The liquid injection hole H3 may be provided, for example, in the negative electrode tab coupling portion 142. When a plurality of negative electrode tab coupling portions 142 are provided, at least one negative electrode tab coupling portion 142 may have the liquid injection hole H3. The liquid injection hole H3 may be provided, for example, on one side or both sides of the negative electrode welded portion W formed in the negative electrode tab coupling portion 142. When manufacturing the cylindrical secondary battery 100, 100', an assembly including the electrode assembly 10, 10' and the negative electrode current collector plate 140 may be accommodated in a battery can 110, and then an electrolyte may be injected. In this case, the liquid injection hole H3 may improve the liquid injection property.

[0214] A plurality of liquid injection holes H3 may be provided. The plurality of liquid injection holes H3 may be arranged approximately symmetrically on the left and right sides with respect to the center in the width direction of the negative electrode tab coupling portion 142. A negative electrode welding portion W for coupling the negative electrode tab coupling portion 142 and the negative electrode non-coated portion 14a may be formed between the liquid injection holes H3 arranged approximately symmetrically in this manner.

[0215] The negative electrode tab binding portion 142 may be formed to have a larger width at a position separated by a predetermined distance from the connection portion toward the longitudinal end of the tab binding portion than at a connection portion between the negative electrode tab binding portion 142 and the central portion 141. At least a part of the region in which the liquid injection hole H3 is formed may be included in an expanded region in which the width at a position separated by a predetermined distance from the connection portion toward the end of the negative electrode tab binding portion 142 is increased compared to the width at the connection portion between the negative electrode tab binding portion 142 and the central portion 141. Meanwhile, the longitudinal end of the negative electrode tab binding portion 142 may be substantially arc-shaped to correspond to the inner circumferential surface of the battery can 110. In addition, the description of the structure of the negative electrode current collector plate 140 in FIG. 25 may be directly applied to the description of the negative electrode current collector plate 140 described with reference to FIGS. 18, 19, 22, 23, etc.

[0216] The cylindrical secondary batteries 100, 100' can be realized by various combinations of the positive electrode current collector plates 120 shown in Figs. 14 to 17 and the negative electrode current collector plates 140 shown in Figs. 22 to 25.

[0217] By making the area of ​​one weld in each current collector plate the same and reducing the number of welds formed in the positive current collector plate 120, the bonding area S1 between the positive uncoated portion 12a and the positive current collector plate 120 can be made smaller than the bonding area S2 between the negative uncoated portion 14a and the negative current collector plate 140. When a positive weld is formed for each positive tab coupling portion 122 and a negative weld is formed for each negative tab coupling portion 142, this condition can be met by making the number of positive tab coupling portions 122 smaller than the number of negative tab coupling portions 142.

[0218] For example, a combination of a positive electrode current collector plate 120 having three positive electrode tab coupling portions 122 as shown in FIG. 16 and a negative electrode current collector plate 140 having four negative electrode tab coupling portions 142 as shown in FIGS. 22 to 25 may be used.

[0219] 26, a battery pack 200 according to an embodiment of the present invention includes a secondary battery assembly in which a plurality of cylindrical secondary batteries 100 according to an embodiment of the present invention are electrically connected as described above, and a pack housing 210 that accommodates the secondary battery assembly. For convenience of illustration, components such as bus bars for electrical connections, a cooling unit, and power terminals are omitted in the drawings of the present invention.

[0220] 27, an automobile 300 according to an embodiment of the present invention may be, for example, an electric automobile, a hybrid automobile, or a plug-in hybrid automobile, and may include a battery pack 200 according to an embodiment of the present invention. The automobile 300 includes a four-wheeled automobile and a two-wheeled automobile. The automobile 300 operates by receiving power from the battery pack 200 according to an embodiment of the present invention.

[0221] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by those having ordinary skill in the art to which the present invention pertains within the scope of the technical spirit of the present invention and the scope of the claims. [Explanation of symbols]

[0222] 10, 10' electrode assembly 12 Positive plate 12a Positive electrode non-coated part 12b Positive electrode active material layer 12c segmental piece 14 Negative plate 14a Negative electrode non-coated part 14b Negative electrode active material layer 16 Separation membrane 20, 100, 100' cylindrical secondary battery 22, 120 Positive current collector 22a Positive electrode weld 22b, 24b Strip 24, 140 Negative current collector 24a Negative electrode weld 110 Battery Can 112 Beading section 114 Crimping section 121 Periphery 122 Positive electrode tab joint 123 Terminal connection section 130 Rivet terminal 142 Negative electrode tab connection 143 Can joint 143a Contact part 143b Connection part 150 Insulator 160 Insulating gasket 170 Cap Plate 180 Sealing Gasket 190 Vent 200 Battery Pack 300 Automobiles H1 cavity H2 Negative electrode collector plate hole H3 liquid injection hole

Claims

1. A jelly-roll type electrode assembly having a structure in which sheet-shaped positive and negative electrode plates and a separator interposed between the positive and negative electrode plates are wound in one direction, the positive electrode plate including a positive electrode non-coated portion exposed to the outside of the separator at a long side end, and the negative electrode plate including a negative electrode non-coated portion exposed to the outside of the separator at a long side end; a positive electrode current collector plate connected to the positive electrode non-coated portion by a positive electrode welding portion; a negative electrode current collector plate connected to the negative electrode non-coated portion by a negative electrode welding portion; A lithium secondary battery comprising: a bonding area S1 between the positive electrode non-coated portion and the positive electrode current collector plate is smaller than a bonding area S2 between the negative electrode non-coated portion and the negative electrode current collector plate.

2. The cylindrical secondary battery according to claim 1 , wherein the number of the negative electrode welds is greater than the number of the positive electrode welds.

3. 2. The cylindrical secondary battery according to claim 1, wherein the positive current collector covers an upper end of the electrode assembly, and the negative current collector covers a lower end of the electrode assembly.

4. the positive current collector plate includes at least one strip extending from a center of the positive current collector plate in a radial direction of the electrode assembly, the positive weld is formed on the strip of the positive current collector plate, 4. The cylindrical secondary battery of claim 3, wherein the negative current collector plate includes one or more strips extending from a center of the negative current collector plate in a radial direction of the electrode assembly, and the negative electrode weld is formed on the strip of the negative current collector plate.

5. 5. The cylindrical secondary battery according to claim 4, wherein the number of strips of the positive current collector plate is two or more and is equally spaced from each other, and the number of strips of the negative current collector plate is two or more and is equally spaced from each other.

6. 5. The cylindrical secondary battery according to claim 4, wherein the number of strips of the negative electrode current collector is M, where M is a natural number of 2 or more, and the number of strips of the positive electrode current collector is 1 to M-1.

7. The cylindrical secondary battery according to claim 4 , wherein the number of the positive electrode welds is smaller than the number of the negative electrode welds.

8. 2. The cylindrical secondary battery according to claim 1, wherein the number of the positive electrode welds is the same as the number of the negative electrode welds, and an area of ​​one of the positive electrode welds is smaller than an area of ​​one of the negative electrode welds.

9. The cylindrical secondary battery according to claim 8 , wherein the positive electrode welded portion and the negative electrode welded portion are formed to extend in a radial direction of the electrode assembly.

10. 4. The cylindrical secondary battery of claim 3, wherein the positive and negative current collectors have the same outer shape as the upper and lower ends of the electrode assembly, respectively.

11. The cylindrical secondary battery is a battery can that receives the electrode assembly through an opening formed on one side thereof and is electrically connected to the negative electrode uncoated portion; a cap plate configured to seal an open portion of the battery can; a rivet terminal that is insulatively provided in a through hole formed in a center portion of a closed portion located on the opposite side of the open portion of the battery can and electrically connected to the positive electrode non-coated portion; The cylindrical secondary battery according to claim 1 , further comprising:

12. The cylindrical secondary battery according to claim 11, wherein the cap plate is not connected to the electrode assembly and does not have polarity.

13. The positive electrode current collector plate is The periphery and a positive electrode tab connection portion extending inward from the peripheral portion and connected to the positive electrode non-coated portion by the positive electrode welding portion; a terminal coupling portion spaced apart from the positive electrode tab coupling portion; Including, The cylindrical secondary battery according to claim 11, wherein the rivet terminal is coupled to the terminal coupling portion.

14. The cylindrical secondary battery according to claim 13, wherein the peripheral portion has a rim shape with at least a portion of an inner region being open.

15. The cylindrical secondary battery according to claim 13, wherein the positive electrode tab coupling portion and the terminal coupling portion are electrically connected to each other through the peripheral portion.

16. The cylindrical secondary battery according to claim 13, wherein the terminal coupling portion is located at a center of the inner space of the peripheral portion.

17. The cylindrical secondary battery of claim 13, wherein the positive electrode tab coupling portion includes a plurality of positive electrode tab coupling portions.

18. The cylindrical secondary battery according to claim 17, wherein the positive electrode tab bonding portions are arranged at equal intervals from each other along the circumferential direction.

19. The cylindrical secondary battery according to claim 17, wherein the extension lengths of the positive electrode tab coupling portions are the same as each other.

20. The cylindrical secondary battery of claim 17, wherein the terminal coupling portion is disposed to be surrounded by a plurality of the positive electrode tab coupling portions.

21. The cylindrical secondary battery according to claim 13, wherein the electrode assembly includes a cavity in a winding center portion of the electrode assembly, and the terminal coupling portion is disposed at a position corresponding to the cavity.

22. the battery can includes a beading portion formed at an end portion adjacent to the opening and pressed inward, The negative electrode current collector plate is a negative electrode tab connection part connected to the negative electrode non-coated part by the negative electrode welding part; a can coupling portion electrically coupled to the beading portion; The cylindrical secondary battery according to claim 13 , comprising:

23. 23. The cylindrical secondary battery of claim 22, wherein the can bond extends from the negative electrode tab bond.

24. The cylindrical secondary battery of claim 22, wherein the negative electrode tab coupling portion and the can coupling portion are indirectly coupled to each other through a center portion of the negative electrode current collector plate, and are not directly coupled to each other.

25. The cylindrical secondary battery according to claim 22 , wherein the negative electrode tab coupling portion has at least one liquid injection hole.

26. The cylindrical secondary battery according to claim 22 , wherein the negative current collector plate includes a circular negative current collector hole in the center of the negative current collector plate.

27. 27. The cylindrical secondary battery according to claim 26, wherein the electrode assembly includes a cavity in a winding center of the electrode assembly, and a diameter of the negative electrode current collector hole is equal to or larger than a diameter of the cavity.

28. 23. The cylindrical secondary battery of claim 22, wherein the negative electrode current collector plate has a leg structure extending in a radial direction of the electrode assembly with the negative electrode tab coupling portion and the can coupling portion connected to each other.

29. The cylindrical secondary battery according to claim 28 , wherein the leg structure includes a plurality of leg structures.

30. 23. The cylindrical secondary battery of claim 22, wherein the positive electrode welded portion is formed for each positive electrode tab coupling portion, the negative electrode welded portion is formed for each negative electrode tab coupling portion, and the number of the positive electrode tab coupling portions is less than the number of the negative electrode tab coupling portions.

31. 31. The cylindrical secondary battery of claim 30, wherein the number of the negative electrode tab binding portions is M, where M is a natural number equal to or greater than 2, and the number of the positive electrode tab binding portions is 1 to M-1.

32. The cylindrical secondary battery according to claim 30, wherein the positive electrode welded portion and the negative electrode welded portion are formed to extend in a radial direction of the electrode assembly.

33. 23. The cylindrical secondary battery of claim 22, wherein the positive electrode weld is formed for each positive electrode tab coupling portion, the negative electrode weld is formed for each negative electrode tab coupling portion, the number of the positive electrode welds is the same as the number of the negative electrode welds, and an area of ​​one of the positive electrode welds is smaller than an area of ​​one of the negative electrode welds.

34. A battery pack comprising the cylindrical secondary battery according to any one of claims 1 to 33.

35. 35. A motor vehicle comprising the battery pack of claim 34.

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