Secondary battery comprising improved current collector plate structures, battery pack and vehicle including the same

Abstract

The secondary battery according to the present invention is a jelly-roll type electrode assembly having a structure in which a positive plate and a negative plate having a sheet shape and a separator interposed between them are wound in one direction, wherein the positive plate includes a positive non-positive portion exposed to the outside of the separator at the long end and the negative plate includes a negative non-positive portion exposed to the outside of the separator at the long end; the electrode assembly comprises: a positive current collector plate joined by the positive non-positive portion and the positive welded portion; and a negative current collector plate joined by the negative non-positive portion and the negative welded portion, wherein the joining area (S1) between the positive non-positive portion and the positive current collector plate is smaller than the joining area (S2) between the negative non-positive portion and the negative current collector plate. According to the present invention, by improving the positive current collector plate and the negative current collector plate, not only can kinetic balance between the positive and negative electrodes be secured, but energy density can also be improved and the bonding strength between components can be strengthened.

Description

Technology Field

[0001] The present invention relates to a secondary battery, and more specifically, to a current collector plate and a cylindrical secondary battery including the same. The present invention is also related to a battery pack including such a cylindrical secondary battery and an automobile. Background Technology

[0002] With the increasing technological development and demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source is rapidly rising. Currently, lithium-ion batteries are the most widely used secondary batteries, and cylindrical, prismatic, and pouch-type secondary batteries are known. In the case of cylindrical secondary batteries, an insulating separator is interposed between the positive and negative electrode plates, and the assembly is wound to form a jelly-roll type electrode assembly, which is then inserted into a battery can. Each electrode plate contains a layer of active material coated on a current collector.

[0003] In lithium-ion batteries, the anode and cathode, where electrochemical reactions actually take place, are the parts that have the greatest influence on charge-discharge characteristics such as capacity and cycle life. In particular, charge-discharge characteristics are affected by the reaction rates of the anode and cathode during the process in which lithium ions (Li+) move through the electrolyte via redox reactions at the electrodes. Therefore, when a kinetic balance—where the reaction rates of the anode and cathode are balanced—is secured, rapid charging can proceed as desired and cycle characteristics are improved. Consequently, securing kinetic balance between the anode and cathode is necessary to facilitate rapid charging and enhance the battery's cycle characteristics.

[0004] Kinetic balance can be achieved by making the migration speeds of lithium ions in the anode and cathode similar. The migration speed of lithium ions is primarily determined by the resistance caused by the active material layer coated on the electrode plate. This resistance refers to the resistance that hinders the charge transfer of lithium ions within and on the surface of the active material particles. Resistance can vary depending on the types of materials constituting the active material layer of the electrode plate, such as active materials, binders, and conductive materials, and can also be influenced by the distribution of binders and conductive materials on the surface of the active material particles.

[0005] Conventionally, the migration speed of lithium ions is controlled by adjusting the composition of the active material layer coated on the electrode plate, known as the "chemistry balance." However, relying solely on this chemistry balance adjustment method presents a problem in that the range of controllable lithium ion migration speeds is very narrow. This is because the compositional range of the active material layer usable in actual lithium-ion batteries is fixed to a certain extent. When attempting to control the lithium ion migration speed within the limitations of process implementation capabilities based on this active material layer composition, adjustments are only possible within a relatively minor range. Therefore, there is a need to develop a technology that enables control of the lithium ion migration speed over a more significant range than that achieved through chemistry balance adjustment.

[0006] Meanwhile, conventionally, a strip-shaped current collection tab is connected to the uncoated area of ​​the electrode plate where the active material layer is not coated, and this current collection tab is used to electrically connect the electrode assembly and the externally exposed electrode terminal. For reference, the positive terminal is the cap plate of the sealing body that seals the opening of the battery can, and the negative terminal is the battery can. However, conventional cylindrical secondary batteries having such a structure have the problem that current is concentrated at the current collection tab, resulting in high resistance, excessive heat generation, and poor current collection efficiency.

[0007] For small cylindrical secondary batteries with form factors such as 18650 or 21700, resistance and heat generation are not major issues. However, if the form factor is increased to apply cylindrical secondary batteries to electric vehicles, a problem may arise where the cylindrical secondary battery ignites due to the generation of a large amount of heat around the current collection tab during rapid charging. To solve this problem, a cylindrical secondary battery (so-called tab-less cylindrical secondary battery) can be used, which has a structure with improved current collection efficiency by designing a positive electrode-free section and a negative electrode-free section to be located at the top and bottom, respectively, of a jelly-roll type electrode assembly, and directly welding a current collection plate to these unfree sections.

[0008] In tapless cylindrical secondary batteries, the welded joint between the unsold section and the current collector plate forms the current path; therefore, the current collector plate is a component that requires critical management. It is necessary for the current collector plate to maximize the contact area with the unsold section as much as possible, thereby minimizing resistance generated at the connection points between components.

[0009] However, conventionally, due to an overemphasis on minimizing resistance, there was no consideration whatsoever for the individual characteristics of the positive current collector welded to the positive-non-positive area and the negative current collector welded to the negative-non-positive area; as they were vaguely applied with identical or similar structures, there is a problem in that there are limitations to the performance of the secondary battery that can be realized. The problem to be solved

[0010] One objective of the present invention is to enable a greater control of the lithium ion movement speed compared to the technology of controlling the lithium ion movement speed by adjusting the chemistry balance between the anode and cathode as described above.

[0011] Another objective of the present invention is to improve the performance of a cylindrical secondary battery by improving the positive electrode current collector and the negative electrode current collector in a tabless cylindrical secondary battery.

[0012] Accordingly, the problem that the present invention aims to solve is to provide a cylindrical secondary battery including an improved current collector plate.

[0013] Another technical objective of the present invention is to provide a battery pack and an automobile including such a secondary battery.

[0014] The technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description of the invention below. means of solving the problem

[0015] The inventors arrived at the present invention by discovering that by improving the positive electrode current collector and the negative electrode current collector of a cylindrical secondary battery, it is possible not only to secure a kinetic balance between the positive and negative electrodes but also to improve energy density and strengthen the bonding strength between components.

[0016] A secondary battery according to the present invention for solving the above-mentioned problem comprises a jelly-roll type electrode assembly having a structure in which a positive plate and a negative plate having a sheet shape and a separator interposed between them are wound in one direction, wherein the positive plate includes a positive non-positive portion exposed to the outside of the separator at the long end and the negative plate includes a negative non-positive portion exposed to the outside of the separator at the long end; an electrode assembly comprising a positive current collector plate joined by the positive non-positive portion and the positive welded portion; and a negative current collector plate joined by the negative non-positive portion and the negative welded portion, wherein the joining area (S1) between the positive non-positive portion and the positive current collector plate is smaller than the joining area (S2) between the negative non-positive portion and the negative current collector plate.

[0017] At least a portion of the above-mentioned positive electrode unoccupied portion can be used as a positive electrode tab itself, and at least a portion of the above-mentioned negative electrode unoccupied portion can be used as a negative electrode tab itself.

[0018] The above positive electrode blank or the above negative electrode blank may be bent along the radial direction of the electrode assembly.

[0019] At least a portion of the above-mentioned positive electrode or negative electrode may be divided into a plurality of segments.

[0020] The above plurality of segments may be folded along the radial direction of the electrode assembly and overlapped in multiple layers.

[0021] The above-mentioned blank portion having a plurality of segments formed therein includes a core-side blank portion adjacent to the winding center of the electrode assembly, an outer-side blank portion adjacent to the outer-side blank portion of the electrode assembly, and an intermediate blank portion interposed between the core-side blank portion and the outer-side blank portion, and the plurality of segments may be formed in the intermediate blank portion.

[0022] The above-mentioned segment may not be formed in the core-side unincorporated portion.

[0023] The height of the outer circumference unoccupied portion may be smaller than the height of the core side unoccupied portion and the intermediate unoccupied portion.

[0024] The height of the above intermediate non-removable portion may increase stepwise from the core side to the outer periphery side of the electrode assembly.

[0025] The electrode assembly includes a cavity in the center of the winding, and the width of the core-side unwound portion may be set so as not to cover the cavity when the plurality of segments are bent.

[0026] At least a portion of the above-mentioned anode-free portion is divided into a plurality of segments, and the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the anode current collector plate may be seated on the folded surface of the above-mentioned anode-free portion and welded to the area where the plurality of segments overlap in multiple layers.

[0027] At least a portion of the above-mentioned cathode-free portion is divided into a plurality of segments, and the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the cathode current collector plate may be seated on the folded surface of the above-mentioned cathode-free portion and welded to the area where the plurality of segments overlap in multiple layers.

[0028] The positive electrode collector plate covers the upper part of the electrode assembly, and the negative electrode collector plate covers the lower part of the electrode assembly; the positive electrode collector plate may include one or more strips extending along the radial direction of the electrode assembly from the center of the positive electrode collector plate, and the positive electrode weld is formed on the strip of the positive electrode collector plate; and the negative electrode collector plate may include one or more strips extending along the radial direction of the electrode assembly from the center of the negative electrode collector plate, and the negative electrode weld is formed on the strip of the negative electrode collector plate.

[0029] The number of strips on the positive current collector plate may be smaller than the number of strips on the negative current collector plate.

[0030] The number of anode welds may be smaller than the number of cathode welds.

[0031] The number of anode welds and the number of cathode welds are equal to each other, and the area of ​​one anode weld may be smaller than the area of ​​one cathode weld.

[0032] The above secondary battery may further include a battery can accommodating the electrode assembly; a cap plate sealing the opening of the battery can; and a rivet terminal installed in a through hole of the battery can.

[0033] The battery can may include an opening on one side, and the closing portion of the battery can located on the opposite side of the opening and the side portion of the battery can are integrally formed, and the rivet terminal may be fixed on the inner surface of the closing portion by riveting.

[0034] The above positive current collector plate may include a rim portion; a positive tab coupling portion extending inward from the rim portion and coupled by the positive non-positive portion and the positive welding portion; and a terminal coupling portion positioned spaced apart from the positive tab coupling portion.

[0035] The above secondary battery further includes an insulator interposed between the closure portion and the positive current collector plate, and the rivet terminal may penetrate the insulator and be coupled to the positive current collector plate.

[0036] The above rivet terminal and the above terminal joint may be joined by welding.

[0037] The above-mentioned rim portion may have a rim shape in which at least a portion of the inner area is empty, and the positive tab coupling portion and the terminal coupling portion may be electrically connected by the rim portion.

[0038] The above positive tab coupling portions may be multiple and arranged at equal intervals along the circumferential direction, and the terminal coupling portion may be arranged to be surrounded by the multiple positive tab coupling portions.

[0039] The electrode assembly may include a cavity in the center of the winding, and the terminal coupling portion may be positioned at a location corresponding to the cavity.

[0040] At least a portion of the above-mentioned anode-free portion is divided into a plurality of segments, and the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the anode tab coupling portion may be welded to an area where the plurality of segments overlap in multiple layers on the folded surface of the above-mentioned anode-free portion.

[0041] The anode weld may be formed by welding the anode tab joint while it is seated on the bent surface of the anode non-part.

[0042] The above-mentioned edge portion, positive tab coupling portion, and terminal coupling portion may all be located within the same plane.

[0043] The above-mentioned cathode collector plate includes a cathode collector plate hole in the center, and the above-mentioned electrode assembly includes a cavity in the center of the winding of the above-mentioned electrode assembly, and the diameter of the cathode collector plate hole may be the same as or larger than the diameter of the cavity.

[0044] At least a portion of the above-mentioned cathode-free portion is divided into a plurality of segments, and the plurality of segments may be bent along the radial direction of the electrode assembly.

[0045] The above plurality of segments may be superimposed in multiple layers along the radial direction of the electrode assembly.

[0046] The above-mentioned cathode current collector plate includes a cathode tab coupling portion joined by the above-mentioned cathode non-coupling portion and the above-mentioned cathode welding portion, and the cathode tab coupling portion may be joined to an area where the above-mentioned plurality of segmented pieces are overlapped in multiple layers.

[0047] The cathode weld may be formed by welding the cathode tab coupling portion while it is seated on the folded surface of the cathode non-coupling portion.

[0048] The present invention provides a battery pack comprising such a secondary battery.

[0049] The present invention provides a vehicle comprising such a battery pack. Effects of the invention

[0050] According to one aspect of the present invention, the movement speed of lithium ions can be controlled by making the bonding area (S1) between the positive electrode non-part and the positive electrode current collector plate smaller than the bonding area (S2) between the negative electrode non-part and the negative electrode current collector plate. There is no need to adjust the chemistry balance between the positive and negative electrodes, and the movement speed of lithium ions can be controlled more broadly compared to the chemistry balance adjustment method without adjusting the chemistry balance between the positive and negative electrodes. Within the limit range of process implementation capability based on the composition of the active material layer, that is, while maintaining the existing process window, the movement speed of lithium ions can be controlled, and a cylindrical secondary battery that facilitates rapid charging and has excellent cycle characteristics can be provided.

[0051] The cylindrical secondary battery according to the present invention is highly suitable for large batteries with increased form factors. It can be manufactured as a cylindrical secondary battery, so-called a tabless cylindrical secondary battery, designed such that a positive electrode-free section and a negative electrode-free section are located at the top and bottom, respectively, of a jelly-roll type electrode assembly, and a positive current collector plate is welded to the positive electrode-free section and a negative current collector plate is welded to the negative electrode-free section to have a structure with improved current collection efficiency. According to the present invention, by using the non-free sections protruding from the top and bottom of the electrode assembly as electrode tabs, the internal resistance of the secondary battery can be reduced and the energy density increased.

[0052] When cylindrical secondary batteries are applied to devices such as automobiles, external shocks and vibrations may frequently occur during use, which can cause damage to the joints for electrical connections between components. Damage to such joints leads to product defects. Alternatively, even if the electrical connection is not completely severed due to damage to the joints, problems may arise such as the generation of excessive heat due to increased resistance or internal short circuits caused by deformation of the components, even if the welding area is partially damaged and the joint area between components is reduced. According to another aspect of the present invention, a cylindrical secondary battery is provided that includes a positive current collector plate having a structure that prevents force from being concentrated at the joints between components even when external shocks and / or vibrations are applied during use, thereby improving the mechanical and electrical performance of the secondary battery.

[0053] According to another aspect of the present invention, a cylindrical secondary battery is provided that includes a negative electrode current collector having a structure suitable for an electrode assembly having a low-resistance structure. This negative electrode current collector not only has a structure capable of improving the bonding strength of the bonding portion with the battery can, but also enables the energy density of the cylindrical secondary battery to be improved. Accordingly, the mechanical and electrical performance of the cylindrical secondary battery is improved. Brief explanation of the drawing

[0054] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a drawing for explaining an electrode assembly that may be included in a cylindrical secondary battery according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a cylindrical secondary battery according to one embodiment of the present invention. Figure 3 is a drawing showing an anode current collector and a cathode current collector according to a comparative example. FIG. 4 is a drawing showing an anode current collector and a cathode current collector according to an embodiment of the present invention. FIGS. 5 to 9 are drawings showing a positive electrode collector plate and a negative electrode collector plate according to another embodiment of the present invention. FIG. 10 is a perspective view of a cylindrical secondary battery according to another embodiment of the present invention. Figure 11 is a cross-sectional view of the cylindrical secondary battery of Figure 10. FIG. 12 is a drawing for explaining an electrode assembly that may be included in a cylindrical secondary battery according to another embodiment of the present invention. FIG. 13 is a cross-sectional view of a cylindrical secondary battery including the electrode assembly of FIG. 12. FIGS. 14 to 17 are drawings showing various forms of positive current collector plates. FIGS. 18 to 25 are drawings showing various forms of cathode current collector plates. FIG. 26 is a schematic diagram showing a battery pack according to one embodiment of the present invention. FIG. 27 is a drawing showing an automobile according to one embodiment of the present invention. Specific details for implementing the invention

[0055] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0056] Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the invention and do not represent all of the technical ideas of the invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0057] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0058] FIG. 1 is a drawing for explaining an electrode assembly that may be included in a cylindrical secondary battery according to one embodiment of the present invention.

[0059] Referring to FIG. 1, the electrode assembly (10) is a jelly-roll type electrode assembly having a structure in which an anode plate (12), a cathode plate (14), and a separator (16) interposed between them are wound in one direction. The electrode assembly (10) can be manufactured by winding a laminate formed by sequentially stacking the anode plate (12), the separator (16), the cathode plate (14), and the separator (16) at least once, with respect to the winding center (C). After the winding is completed, the electrode assembly (10) takes on a roughly cylindrical shape. When viewed from the top or bottom of the electrode assembly (10), the outer shape of the electrode assembly (10) is circular.

[0060] The positive plate (12) has a structure in which a positive active material layer (12b) is coated on one or both sides of a sheet-shaped positive current collector having a long side and a short side, and includes a positive non-positive portion (12a) at one long side end along the winding direction (X). The positive non-positive portion (12a) can be continuously formed along one end of the positive plate (12). The negative plate (14) also has a structure in which a negative active material layer (14b) is coated on one or both sides of a sheet-shaped negative current collector having a long side and a short side, and includes a negative non-positive portion (14a) in which an active material layer is not coated at one long side end along the winding direction (X). The negative non-positive portion (14a) can also be continuously formed along one end of the negative plate (14).

[0061] The current collector can be appropriately selected according to the polarity of the electrode plates, and while aluminum, copper, nickel, or stainless steel may be used as the material, it is not necessarily limited thereto, and metals and metal alloys commonly used as current collector materials may be adopted. For example, the positive current collector may be aluminum or an aluminum alloy, and the negative current collector may be copper or a copper alloy.

[0062] In the present invention, the positive active material coated on the positive current collector and the negative active material coated on the negative current collector may be used without limitation as long as they are active materials known in the art.

[0063] In one example, the positive active material is the general chemical formula A[A x M y ]O 2+z It may include an alkali metal compound represented by (A includes at least one element among Li, Na and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Sc, Ru, and Cr; x ≥ 0, 1 ≤ x+y ≤ 2, 0.1 ≤ z ≤ 2; stoichiometry x, y and z are selected so that the compound maintains electrical neutrality).

[0064] Preferably, the positive electrode active material comprises a lithium transition metal oxide. It may comprise a nickel-cobalt-manganese-based lithium oxide, among which a high-concentration nickel-cobalt-manganese-based lithium oxide with a high nickel content among the transition metals may be included.

[0065] In another example, the positive active material is an alkali metal compound xLiM disclosed in US6,677,082, US6,680,143, etc. 1 O2 - (1x)Li2M 2 O3(M 1 It comprises at least one element having an average oxidation state of 3; M 2 It contains at least one element having an average oxidation state of 4; 0≤x≤1).

[0066] In another example, the positive active material is, with the general chemical formula Li a M 1 x Fe 1­x M 2 y P 1­y M 3 z O 4­z (M 1 It contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Mg, and Al; M 2 ... comprises at least one element selected from Ti, Mn, Co, Fe, Cr, Mo, Ni, Nd, Mg, Al, As, Sb, Si, Ge, V, and S; M 3 It may be a lithium metal phosphate represented as Li3M2(PO4)3 [M comprises a halogen element optionally containing F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; stoichiometric coefficients a, x, y and z are selected so that the compound remains electrically neutral), or Li3M2(PO4)3 [M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Mg and Al].

[0067] Preferably, the positive active material may include primary particles and / or secondary particles formed by the aggregation of primary particles.

[0068] In one example, the negative electrode active material may be a carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound, etc. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V may also be used as negative electrode active materials. As for the carbon material, low-crystallinity carbon, high-crystallinity carbon, etc. may all be used.

[0069] The separator (16) may be a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., used alone or in a laminated form. As another example, the separator (16) may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc.

[0070] At least one surface of the separator (16) may include a coating layer of inorganic particles. It is also possible for the separator (16) itself to be composed of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure combined with a binder such that interstitial volume exists between adjacent particles.

[0071] The inorganic particles may be composed of inorganic materials having a dielectric constant of 5 or higher. As a non-limiting example, the inorganic particles are Pb(Zr,Ti)O3(PZT), Pb 1­x La x Zr 1­y Ti y O3(PLZT), PB(Mg3Nb 2 / 3It may include at least one material selected from the group consisting of O3PbTiO3(PMNPT), BaTiO3, hafnia(HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0072] An insulating coating layer (18) may be further formed at the boundary between the active material layer (12b, 14b) and the uncoated portion (12a, 14a). The insulating coating layer (18) may be formed such that at least a portion overlaps the boundary between the active material layer (12b, 14b) and the uncoated portion (12a, 14a). The insulating coating layer (18) may include a polymer resin and may include an inorganic filler such as Al2O3. Electrical contact between the positive plate (12) and the negative plate (14) can be effectively prevented by the insulating coating layer (18). The insulating coating layer (18) may be omitted. The insulating coating layer (18) may serve to mechanically support the uncoated portion (12a, 14a) from the side so that it does not bend excessively toward the separator (16) when the uncoated portion (12a, 14a) is folded.

[0073] Each unoccupied portion (12a, 14a) is positioned in opposite directions. And, each unoccupied portion (12a, 14a) is exposed to the outside of the separator (16). In this electrode assembly (10), at least a portion of the positive unoccupied portion (12a) can be used as a positive tab itself, and at least a portion of the negative unoccupied portion (14a) can be used as a negative tab itself.

[0074] FIG. 2 is a schematic diagram of a cylindrical secondary battery according to one embodiment of the present invention.

[0075] Referring to FIG. 2, the 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 collector plate (22) and a negative electrode collector plate (24). These may be housed together with an electrolyte in a battery can (not shown), which is an external case.

[0076] The electrolyte is A+ B - It may be a salt having a structure like that. Here, A + is Li + , Na + , K + It includes alkali metal cations such as or ions composed of combinations thereof. And B - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - ,　 CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It includes one or more anions selected from the group consisting of

[0077] The electrolyte can also be dissolved in an organic solvent and used as an electrolyte solution. As organic solvents, 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), gamma-butyrolactone (γ-butyrolactone), or mixtures thereof may be used.

[0078] In the electrode assembly (10) of FIG. 1, each non-electrode portion (12a, 14a) does not have a separate current collection tab attached to it and is used as an electrode tab itself. The electrode assembly (10) includes the positive electrode non-electrode portion (12a) at the top of the electrode assembly (10) and the negative electrode non-electrode portion (14a) at the bottom of the electrode assembly (10). In other words, the positive electrode non-electrode portion (12a) is provided at the top of the electrode assembly (10) in the height direction (a direction parallel to the Z-axis), and the negative electrode non-electrode portion (14a) is provided at the bottom of the electrode assembly (10) in the height direction.

[0079] As illustrated in FIG. 2, the positive electrode collector plate (22) can be accommodated in a battery can (not illustrated) with the positive electrode collector plate (22) covering the top of the electrode assembly (10) and the negative electrode collector plate (24) covering the bottom of the electrode assembly (10). The positive electrode collector plate (22) and the negative electrode collector plate (24) may have the same outer shape as the top and bottom of the electrode assembly (10). For example, the positive electrode collector plate (22) and the negative electrode collector plate (24) may be in the shape of a disc. Of course, the specific shape of the positive electrode collector plate (22) and the negative electrode collector plate (24) and their position within the battery can may differ from that illustrated.

[0080] The positive current collector plate (22) may be a metal of the same type as the positive current collector of the positive plate (12) of the electrode assembly (10), or a material that welds well with the positive current collector. The negative current collector plate (24) may be a metal of the same type as the negative current collector of the negative plate (14) of the electrode assembly (10), or a material that welds well with the negative current collector. For example, the positive current collector plate (22) may be aluminum or aluminum alloy, steel, stainless steel, etc., and the negative current collector plate (24) may be copper or copper alloy, nickel or nickel alloy, steel, stainless steel, or a composite material thereof. For example, the negative current collector plate (24) may be a clad metal with nickel plated over copper.

[0081] The positive electrode collector plate (22) is joined to the positive electrode non-positive portion (12a) of the electrode assembly (10). The negative electrode collector plate (24) is joined to the negative electrode non-positive portion (14a) of the electrode assembly (10). The positive electrode non-positive portion (12a) and the positive electrode collector plate (22) are directly joined through welding. The negative electrode non-positive portion (14a) and the negative electrode collector plate (24) are also directly joined through welding. A weld is formed at each welding site. The present invention is not limited by the type of positive electrode collector plate (22) welded at a specific location on the positive electrode non-positive portion (12a) and the type of negative electrode collector plate (24) welded at a specific location on the negative electrode non-positive portion (14a). Welding methods may include, for example, laser welding, resistance welding, and ultrasonic welding, but the welding method is not limited thereto.

[0082] Each current collector plate (22, 24) guides the current generated in each electrode plate (12, 14) of the electrode assembly (10) to each electrode terminal. Each current collector plate (22, 24) is a component connected to derive current from each uncoated portion (12a, 14a), which is the end of each electrode plate (12, 14). For welding each current collector plate (22, 24) and each uncoated portion (12a, 14a), each uncoated portion (12a, 14a) forming the end of the electrode assembly (10), which is wound in a jelly-roll type, can be bent flat so that surface contact is made with each current collector plate (22, 24), and then laser welding can be performed.

[0083] Preferably, each uncoupling section (12a, 14a) is folded toward the winding center (C) of the electrode assembly (10) as shown in FIG. 2. The folded state of the positive uncoupling section (12a) can be seen through an enlarged view of section A. The folded state of the negative uncoupling section (14a) is similar. After folding each uncoupling section (12a, 14a), each current collector plate (22, 24) is welded to each uncoupling section (12a, 14a) to join them. Since the positive uncoupling section (12a) acts as a positive tab and the negative uncoupling section (14a) acts as a negative tab, and the positive current collector plate (22) and the negative current collector plate (24) are connected to external electrode terminals, the current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly (10) (see arrow), thereby lowering the resistance of the secondary battery. This structure is particularly suitable for high-output secondary batteries.

[0084] Since the current is drawn in and out by directly connecting each current collection plate (22, 24) to each unoccupied portion (12a, 14a), a separate current collection tap is not required. Therefore, since the installation process of the current collection tap is unnecessary, productivity can be improved. In addition, because the space required to store the current collection tap can be reduced, the entire secondary battery becomes compact and space utilization is improved.

[0085] Here, it is important to note that the bonding area (S1) between the positive electrode non-bonding portion (12a) and the positive electrode collector plate (22) is smaller than the bonding area (S2) between the negative electrode non-bonding portion (14a) and the negative electrode collector plate (24). <S2). 각 무지부와 각 집전판간의 결합은 용접부에 의해 달성된다. 용접부는 무지부에서 집전판으로, 그리고 집전판에서 무지부로의 전류 패스가 되며, 용접부의 면적, 즉 용접 면적이 집전판과 무지부 사이의 결합 면적 또는 직접 접촉 면적에 해당한다. 결합 면적이 커지면 그만큼 전류 패스가 넓어지는 것이므로 저항은 작아진다. 양극 무지부(12a)와 양극 집전판(22)간의 결합 면적(S1)을 음극 무지부(14a)와 음극 집전판(24)간의 결합 면적(S2)보다 작게 함으로써, 양극에서의 저항을 증가시키면 양극과 음극의 키네틱 밸런스를 맞출 수 있다.

[0086] Although various types of active materials were exemplified earlier, within the range of commonly used positive and negative electrode active materials, the lithium ion migration speed at the positive electrode tends to be faster than that at the negative electrode. If there is a significant difference in the lithium ion migration speeds between the electrodes, battery reactions such as charging and discharging cannot occur smoothly. Specifically, during charging, lithium ions must move from the positive electrode to the negative electrode. While the lithium ion migration speed is fast at the positive electrode, it is slow at the negative electrode. If lithium ions moving from the positive electrode fail to move smoothly and become stagnant at the negative electrode, it causes damage such as lithium deposition. This is even more severe in the case of rapid charging. Therefore, it is desirable to achieve a kinetic balance between the positive and negative electrodes by intentionally reducing the lithium ion migration speed at the positive electrode.

[0087] Of course, it is possible to achieve a kinetic balance between the anode and cathode by intentionally increasing the lithium ion migration speed at the cathode. However, this method is a chemistry-balancing approach, such as increasing the porosity of the cathode to provide more space for lithium ion movement or increasing the content of conductive materials in the cathode active material layer. The former is undesirable in terms of energy density because it increases the thickness of the cathode plate, while the latter is undesirable from an industrial perspective due to increased costs. Therefore, if the process margin allows, it is preferable to lower the lithium ion migration speed at the cathode. Conventional methods for lowering the cathode's lithium ion migration speed involve chemistry-balancing techniques, such as reducing the content of conductive materials in the cathode active material layer. However, since the composition range of the active material layer usable in actual lithium-ion batteries is somewhat fixed, there are limits to the extent to which adjustments can be made using this chemistry-balancing method.

[0088] The present invention controls the lithium ion migration speed by adjusting resistance through the composition of positive and negative active materials, as in the chemistry balance method, but rather influences the lithium ion migration speed at each electrode plate by adjusting the resistance based on the bonding area between the current collector plate and the non-positive portion at each electrode. Specifically, the bonding area (S1) between the positive current collector plate and the positive non-positive portion is made smaller than the bonding area (S2) between the negative current collector plate and the negative non-positive portion, thereby making the resistance at the positive current collector plate greater than the resistance at the negative current collector plate. During charging, electrons must move from the positive electrode to the negative electrode so that the negative electrode can receive the lithium ions moving from the positive electrode. By making the resistance of the positive electrode larger, a bottleneck is created in the flow of electrons attempting to move from the positive electrode to the negative electrode, thereby reducing the lithium ion migration speed at the positive electrode.

[0089] S1 below <S2인 관계를 구현하기 위한 다양한 실시예에 대해 설명한다.

[0090] First, to aid understanding, a comparative example where S1=S2 is explained. Figure 3 is a diagram showing a positive electrode collector plate and a negative electrode collector plate according to the comparative example.

[0091] Referring to FIG. 3, the positive electrode collector plate (32) and the negative electrode collector plate (34) are depicted in the shape of a disc. In FIG. 3, the area of ​​one positive weld (32a) formed between the positive electrode uncoordinated portion (12a in FIG. 2) and the positive electrode collector plate (32) and the area of ​​one negative electrode weld (34a) formed between the negative electrode uncoordinated portion (14a in FIG. 2) and the negative electrode collector plate (34) are equal to each other, and the number of positive electrode welds (32a) and the number of negative electrode welds (34a) are equal. That is, without distinction between the positive electrode collector plate (32) and the negative electrode collector plate (34), the area of ​​the uncoordinated portion and the welded portion (welding area or bonding area) in each collector plate are equal to each other.

[0092] On the other hand, FIG. 4 is a drawing showing an anode current collector and a cathode current collector according to one embodiment of the present invention.

[0093] Referring to FIG. 4, the area of ​​one anode weld (22a) formed between the anode non-positive portion (12a in FIG. 2) and the anode collector plate (22) and the area of ​​one cathode weld (24a) formed between the cathode non-positive portion (14a in FIG. 2) and the cathode collector plate (24) are equal to each other, and the number of cathode welds (24a) is greater than the number of anode welds (22a). For example, the illustration shows a case where the number of anode welds (22a) is 3 and the number of cathode welds (24a) is 4. In this way, by making the weld area equal and adjusting the number of welds, S1 between the bonding area (S1) between the anode non-positive portion (12a) and the anode collector plate (22) and the bonding area (S2) between the cathode non-positive portion (14a) and the cathode collector plate (24) <S2인 관계가 되도록 할 수 있다.

[0094] In the illustrated example, the anode weld (22a) and the cathode weld (24a) may be formed extending along the radial direction of the electrode assembly (10). Each weld (22a, 24a) may include a weld bead. The size and shape of the weld bead constituting the weld (22a, 24a) may vary. For example, the weld bead may be a single circular shape formed by spot welding. It may also be a shape in which multiple circular shapes overlap. The overlapping circular shapes may form a single continuous line or form a shape roughly like a triangle. The weld includes not only weld beads that are distinct from each other by being formed separately in this way, but also cases where weld beads overlap at least partially to form a single mass. In the example illustrated in FIG. 4, each weld (22a, 24a) is exemplified as a continuous line shape, but it does not exclude cases where a single circular shape extends discontinuously in places along the radial direction of the electrode assembly (10). When multiple weld beads are formed, the total weld area is determined by adding the areas of each weld bead.

[0095] Furthermore, the weld bead is not formed planarly only on the surfaces of the two members joined by welding, but has a three-dimensional shape with a thickness that extends at least to the contact interface between the two members. The weld area referred to in this specification can be understood as the cross-sectional area of ​​the weld bead at the contact interface between the collector plate and the uncoated portion. However, the cross-sectional area at the contact interface is difficult to manage as a design factor. In the case of welding under normal conditions, a correspondence exists between the cross-sectional area at the contact interface and the surface area. Therefore, the surface area, which is easy to manage as a design factor, is defined as the weld area.

[0096] FIG. 5 is a drawing showing a positive electrode collector plate and a negative electrode collector plate according to another embodiment. Compared to FIG. 4, where the positive electrode collector plate (22) and the negative electrode collector plate (24) are in the shape of a disc, FIG. 5 shows that the shape of the positive electrode collector plate (22) and the negative electrode collector plate (24) has been changed.

[0097] Referring to FIG. 5, the positive electrode collector plate (22) includes one or more strips (22b) extending along the radial direction of the electrode assembly (10) from the center of the positive electrode collector plate (22). An positive electrode weld (22a) is formed on the strip (22b) of the positive electrode collector plate (22) to be joined with the positive electrode non-coupling portion (12a). The negative electrode collector plate (24) also includes one or more strips (24b) extending along the radial direction of the electrode assembly (10) from the center of the negative electrode collector plate (24), and a negative electrode weld (24a) is formed on the strip (24b) of the negative electrode collector plate (24) to be joined with the negative electrode non-coupling portion (14a).

[0098] The strips (22b) of the positive electrode collector plate (22) may be two or more and spaced equally apart from each other, and the strips (24b) of the negative electrode collector plate (24) may be two or more and spaced equally apart from each other. When forming a welded portion for each strip, it may be desirable to space the strips equally apart from each other in order to form an even current path from each electrode tab.

[0099] The shape and number of strips may vary, and the number of strips (22b) of the positive collector plate (22) may be smaller than the number of strips (24b) of the negative collector plate (24). For example, if the number of strips (24b) of the negative collector plate (24) is M, the number of strips (22b) of the positive collector plate (22) may be 1 to M-1 (M is a natural number greater than or equal to 2). An example given in FIG. 5 is the case where there are 3 strips (22b) of the positive collector plate (22) and 4 strips (24b) of the negative collector plate (24). If the strips are arranged at equal intervals from each other, the strips (22b) of the positive collector plate (22) in FIG. 5 may be arranged in a Y shape. The strips (24b) of the negative collector plate (24) may be arranged in a cross shape.

[0100] One weld can be formed for each strip. If the number of strips (22b) of the positive collector plate (22) is smaller than the number of strips (24b) of the negative collector plate (24), and the area of ​​one positive weld (22a) is not larger than the area of ​​one negative weld (24a), then S1 between the bonding area (S1) between the positive non-positive part (12a) and the positive collector plate (22) and the bonding area (S2) between the negative non-positive part (14a) and the negative collector plate (24) <S2인 관계가 되도록 할 수 있다.

[0101] FIGS. 6 to 8 are variations of FIG. 5. In FIG. 6, there are 4 strips (22b) of the positive electrode collector plate (22) and 6 strips (24b) of the negative electrode collector plate (24). In FIG. 7, there are 2 strips (22b) of the positive electrode collector plate (22) and 4 strips (24b) of the negative electrode collector plate (24). In FIG. 8, there are 2 strips (22b) of the positive electrode collector plate (22) and 3 strips (24b) of the negative electrode collector plate (24).

[0102] In the embodiments given above, the area of ​​one weld in each collector plate is the same, but the number of welds formed on the positive collector plate (22) is reduced so that the bonding area (S1) between the positive non-positive portion (12a) and the positive collector plate (22) is smaller than the bonding area (S2) between the negative non-positive portion (14a) and the negative collector plate (24).

[0103] As another example of making the bonding area (S1) between the positive electrode uncoated portion (12a) and the positive electrode collector plate (22) smaller than the bonding area (S2) between the negative electrode uncoated portion (14a) and the negative electrode collector plate (24), it may be possible to make the area of ​​one weld formed on the positive electrode collector plate (22) smaller than the area of ​​one weld formed on the negative electrode collector plate (24), even though the number of welds on each collector plate is the same. However, since there may be a contact risk when the area of ​​one weld is reduced, it is preferable to make the area of ​​one weld the same on each collector plate (22, 24) and adjust the number accordingly.

[0104] FIG. 9 is a drawing showing an anode current collector and a cathode current collector according to another embodiment of the present invention.

[0105] Referring to FIG. 9, the number of positive welds (22a) formed between the positive non-positive portion (12a in FIG. 2) and the positive collector plate (22) and the number of negative welds (24a) formed between the negative non-positive portion (14a in FIG. 2) and the negative collector plate (24) are the same, but the size of one positive weld (22a) is smaller than the size of one negative weld (24a), so S1 <S2인 관계를 만족한다. 여기에서도 양극 용접부(22a)와 음극 용접부(24a)가 전극 조립체(10)의 반경 방향을 따라 연장되며 형성된다.

[0106] In this way, various current collector plates can be implemented by varying the number of welds formed on each current collector plate or the area of ​​a single weld, varying the shape of each electrode plate, or, for example, designing each electrode plate to include a strip and changing the number of strips or the number of welds formed on a single strip. At this time, the condition of making the bonding area (S1) between the positive electrode non-part and the positive current collector plate smaller than the bonding area (S2) between the negative electrode non-part and the negative current collector plate is satisfied, thereby controlling the movement speed of lithium ions. In addition, by further considering the resistance of the positive active material and the negative active material, and having an appropriate ratio of bonding areas (S1 / S2) between the positive current collector plate and the negative current collector plate, the kinetic balance between the positive and negative electrodes can be adjusted more precisely.

[0107] Since it is desirable for process control to apply the same welding process to the anode and cathode, one welded portion of the same area is formed for each strip, and the number of strips (24b) of the cathode collector plate (24) is M, and the number of strips (22b) of the anode collector plate (22) is 1 to M-1 (M is a natural number greater than or equal to 2), so that S1 between the bonding area (S1) between the anode non-bonded portion (12a) and the anode collector plate (22) and the bonding area (S2) between the cathode non-bonded portion (14a) and the cathode collector plate (24) <S2인 관계가 되도록 한다. 그러면 양극 집전판과 음극 집전판에서의 적절한 결합 면적의 비(S1 / S2)는 1 / M 내지 (M-1) / M의 범위 내에서 조절될 수 있다. 그리고, 양극 집전판과 음극 집전판에서의 적절한 결합 면적의 비(S1 / S2)는 용접부의 개수에 의한 용접 강도 측면, 저항 측면을 모두 고려하여 결정할 수 있다.

[0108] FIGS. 6 to 8 are variations of FIG. 5. In FIG. 6, there are 4 strips (22b) of the positive electrode collector plate (22) and 6 strips (24b) of the negative electrode collector plate (24). In FIG. 7, there are 2 strips (22b) of the positive electrode collector plate (22) and 4 strips (24b) of the negative electrode collector plate (24). In FIG. 8, there are 2 strips (22b) of the positive electrode collector plate (22) and 3 strips (24b) of the negative electrode collector plate (24).

[0109] From the perspective of efficiently managing the inflow and outflow of current and reducing internal resistance, it is better for each joint area (S1, S2) to be larger. Conventionally, focusing solely on minimizing resistance led to an attempt to unconditionally increase the welding area without separately considering the individual characteristics of the positive and negative current collector plates. The present invention ensures that each joint area (S1, S2) has a suitable value in terms of considering the inflow and outflow of current and internal resistance, and even within such a range of values, S1 <S2가 되도록 함으로써 양극과 음극간의 키네틱 밸런스까지 맞출 수 있도록 한 것이므로 기술적 의의가 있고 고도한 것이다.

[0110] Meanwhile, since 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 plate and the non-current part, that is, the number of welds. Therefore, the inventors have reduced the number of anode welds while S1 <S2로 하는 경우가 급속 충전의 용이성 관점에서 더욱 바람직하다고 제안한다.

[0111] As previously explained, in the case of the positive and negative current collector plate structures of the comparative example illustrated in FIG. 3, the number of welds is the same, with four welds included on each of the positive and negative current collector plates, whereas in the case of the positive and negative current collector plates according to an embodiment of the present invention illustrated in FIG. 4, three welds are formed on the positive current collector plate and four welds are formed on the negative current collector plate. The case of FIG. 4 is preferred from the perspective of rapid charging.

[0112] As such, in the embodiments of the present invention, the kinetic balance between the anode and the cathode can be adjusted by adjusting the bonding area with the non-bonding portion of each current collector plate. The bonding area (S1) at the anode current collector plate is smaller than the bonding area (S2) at the cathode current collector plate. By using the same active material, conductive material, and binder type and content as in the prior art, the interfacial resistance is maintained, while the increase in resistance due to the reduction in the contact area at the anode causes a bottleneck in electron movement, thereby reducing the lithium ion movement speed and consequently improving the kinetic balance between the anode and the cathode.

[0113] Accordingly, according to the present invention, it becomes possible to adjust the lithium ion migration speed more significantly by applying a method of adjusting the kinetic balance of lithium ions by controlling the bonding area between the unbonded portion and the current collector plate in a jelly-roll type electrode assembly without adjusting the chemistry between the positive and negative electrodes. That is, by applying a differential structure that considers the individual characteristics of each current collector plate, such as varying the number of welded portions in the positive and negative current collector plates, the characteristics of a cylindrical secondary battery containing such a structure can be improved.

[0114] Thus, according to the present invention, there is no need to adjust the chemistry balance between the anode and the cathode, and the lithium ion migration speed can be controlled over a wider range compared to the chemistry balance adjustment method without adjusting the chemistry balance between the anode and the cathode. Within the limit range of process implementation capability based on the composition of the active material layer, that is, while maintaining the existing process window, the lithium ion migration speed can be controlled, thereby providing a cylindrical secondary battery that facilitates rapid charging and has excellent cycle characteristics.

[0115] FIG. 10 is a perspective view of a cylindrical secondary battery according to another embodiment of the present invention. FIG. 11 is a cross-sectional view of the cylindrical secondary battery of FIG. 10.

[0116] Referring to FIGS. 10 and 11, the cylindrical secondary battery (100) includes an electrode assembly (10), a positive electrode current collector (120), and a negative electrode current collector (140). Additionally, 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.

[0117] The battery can (110) is approximately cylindrical in shape. The battery can (110) has an opening formed on one side, in this embodiment at the bottom, and is made of a conductive material such as metal. The opposite side of the opening in the battery can (110) is a closed part. The material of the battery can (110) may be, for example, aluminum, steel, or stainless steel. The side (outer surface) and the top surface of the battery can (110) may be formed integrally. The top surface of the battery can (110) (a surface parallel to the XY plane) has an approximately flat shape. The battery can (110) accommodates the electrode assembly (10) through the opening and also accommodates the electrolyte.

[0118] Here, the electrode assembly (10) may be the electrode assembly described above with reference to FIG. 1, and the positive electrode unoccupied portion (12a) and the negative electrode unoccupied portion (14a) extend in opposite directions along the height direction (a direction parallel to the Z-axis) of the cylindrical secondary battery (100). The positive electrode unoccupied portion (12a) extends toward the closed portion of the battery can (110), and the negative electrode unoccupied 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).

[0119] The battery can (110) is electrically connected to the electrode assembly (10). The battery can (110) is electrically connected, for example, to the negative electrode non-existent portion (14a) of the electrode assembly (10). Accordingly, the battery can (110) may have the same polarity as the negative electrode non-existent portion (14a). The entire surface of the battery can (110) may function as a negative terminal.

[0120] The rivet terminal (130) may be made of a conductive metal material. The rivet terminal (130) is installed, for example, in a through hole formed in the center of the closure of the battery can (110). A portion of the rivet terminal (130) may be exposed to the top of the battery can (110), and the remaining portion may be located inside the battery can (110). The rivet terminal (130) may be fixed on the inner surface of the closure of the battery can (110), for example, by riveting.

[0121] An insulator (150) is interposed between the closed portion of the battery can (110) and the positive current collector plate (120). A rivet terminal (130) can penetrate the insulator (150) and be electrically connected to the positive non-positive portion (12a) provided on the positive plate (12) of the electrode assembly (10). In this case, the rivet terminal (130) may have a positive polarity. Thus, the rivet terminal (130) may have a polarity opposite to that of the battery can (110) and can be used as a positive terminal.

[0122] When the rivet terminal (130) has a positive polarity in this way, the rivet terminal (130) is installed 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 realized 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). Or, a method of structurally and firmly fixing the rivet terminal (130) so that contact between the rivet terminal (130) and the battery can (110) is impossible may be applied. Or, multiple methods among those described above may be applied together.

[0123] In this way, the cylindrical secondary battery (100) has a structure in which the area occupied by the rivet terminal (130) among the upper surface of the battery can (110) and the rivet terminal (130) can be used as the positive terminal and the negative terminal, respectively. Accordingly, when electrically connecting multiple cylindrical secondary batteries (100), the cylindrical secondary battery (100) can connect both the positive and negative terminals in one direction, thereby simplifying the electrical connection structure. In addition, since the cylindrical secondary battery (100) has a structure in which most of the surface opposite the opening of the battery can (110) can be used as the negative terminal, it has the advantage of being able to secure a sufficient area for welding components for electrical connection.

[0124] As illustrated in detail in FIG. 11, the battery can (110) may have a beading portion (112) and a crimping portion (114) formed at its bottom. The beading portion (112) is located at the bottom of the electrode assembly (10). The beading portion (112) is formed by pressing the outer circumference of the battery can (110). The beading portion (112) prevents the electrode assembly (10), which may have a size approximately corresponding to the inner diameter of the battery can (110), from coming out through the opening formed at the bottom of the battery can (110), and can function as a support portion on which the cap plate (170) is seated.

[0125] The crimping portion (114) is formed on the side facing the opening of the battery can (110) rather than the beading portion (112). In this embodiment, the crimping portion (114) is formed below the beading portion (112). The crimping portion (114) has a shape that extends and is bent toward the opening of the battery can (110) so as to cover the outer surface of the cap plate (170) positioned below the beading portion (112) and a part of the lower surface of the cap plate (170).

[0126] However, the present invention does not exclude cases where the battery can (110) does not have such a beading portion (112) and / or a crimping portion (114). That is, in the present invention, if the battery can (110) does not have a beading portion (112) and / or a crimping portion (114), the fixing of the electrode assembly (10) and / or the sealing of the battery can (110) can be realized, for example, by the additional application of a component that can function as a stopper for the electrode assembly (10). In addition, if 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) can be realized, for example, by the additional application of a structure on which the cap plate (170) can be seated and / or by welding between the battery can (110) and the cap plate (170). That is, the cap plate (170) can seal the opening of the battery can (110). For example, the applicant’s published patent KR 10-2019-0030016 A discloses a cylindrical battery cell with a beading portion omitted, and such a structure may be adopted in the present invention.

[0127] Referring further to FIG. 11, the cap plate (170) may be made of, for example, a metal material to ensure rigidity. The cap plate (170) may cover the opening 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. Not having polarity may mean that the cap plate (170) is not connected to the electrode assembly (10). It may also mean that it 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 terminal or a negative terminal. The cap plate (170) does not need to be electrically connected to the electrode assembly (10) and the battery can (110), and its material does not necessarily have to be a conductive metal.

[0128] If the battery can (110) is provided with a beading portion (112), the cap plate (170) can be placed on the beading portion (112) formed on the battery can (110). Additionally, if the battery can (110) is provided with a crimping portion (114), the cap plate (170) can be secured 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).

[0129] The cap plate (170) may further include a venting portion (190) formed to prevent the internal pressure from increasing beyond a preset value due to gas generated inside the battery can (110). The venting portion (190) corresponds to an area of ​​the cap plate (170) that has a thinner thickness compared to the surrounding area. The venting portion (190) is structurally weaker compared to the surrounding area. Therefore, if an abnormality occurs in the cylindrical secondary battery (100) and the internal pressure of the battery can (110) increases above a certain level, the venting portion (190) ruptures, and the gas generated inside the battery can (110) is discharged. The venting portion (190) can be formed, for example, by notching on one or both sides of the cap plate (170) to partially reduce the thickness of the battery can (110).

[0130] The positive electrode collector plate (120) is coupled to the upper part of the electrode assembly (10). The positive electrode collector plate (120) is made of a conductive metal material and is connected by welding to the positive electrode non-conductive portion (12a). The negative electrode collector plate (140) is coupled to the lower part of the electrode assembly (10). The negative electrode collector plate (140) is made of a conductive metal material and is connected by welding to the negative electrode non-conductive portion (14a). The negative electrode collector plate (140) can be fixed by interposing its perimeter area between the inner surface of the battery can (110) and the sealing gasket (180). In this case, the negative electrode collector plate (140) may be welded onto the seating surface formed by the beading portion (112) of the battery can (110).

[0131] In this cylindrical secondary battery (100), the bonding area (S1) between the positive electrode non-bonding portion (12a) and the positive electrode current collector (120) is smaller than the bonding area (S2) between the negative electrode non-bonding portion (14a) and the negative electrode current collector (140). S1 <S2인 관계를 만족할 때에 키네틱 밸런스 측면에서의 이점은 앞서 설명한 바와 같다. S1<S2인 관계를 만족하는 다양한 실시예의 양극 집전판(120)과 음극 집전판(140)은 후술하기로 한다.

[0132] The cylindrical secondary battery (100) may be, for example, a cylindrical secondary battery in which the ratio of the form factor (defined as the ratio of the diameter of the cylindrical secondary battery to the height, i.e., the ratio of the diameter (Φ) to the height (H)) is approximately greater than 0.4. Such a secondary battery is suitable, for example, as a high-output, high-capacity secondary battery for a hybrid vehicle.

[0133] Here, the form factor refers to a value representing the diameter and height of a cylindrical secondary battery. The cylindrical secondary battery (100) may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 represents that the cross-section of the cell is circular.

[0134] The cylindrical secondary battery (100) may have a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.436. The cylindrical secondary battery (100) may have a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of approximately 0.640. The cylindrical secondary battery (100) may have a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of approximately 0.418. The cylindrical secondary battery (100) may have a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.600. The cylindrical secondary battery (100) may have a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of approximately 0.575.

[0135] Conventionally, secondary batteries with a form factor ratio of approximately 0.4 or less were used. That is, conventionally, for example, 18650 cells and 21700 cells were used. In the case of the 18650 cell, its diameter is approximately 18 mm, its height is approximately 65 mm, and its form factor ratio is approximately 0.277. In the case of the 21700 cell, its diameter is approximately 21 mm, its height is approximately 70 mm, and its form factor ratio is approximately 0.300.

[0136] FIG. 12 is a drawing for illustrating an electrode assembly that may be included in a cylindrical secondary battery according to another embodiment of the present invention. In the description referring to FIG. 2 above, it was mentioned that each unwound portion (12a, 14a) of the electrode assembly (10) of FIG. 1 may be bent toward the winding center (C) of the electrode assembly (10). FIG. 12 illustrates a preferred example of an electrode assembly to which such bending is applied.

[0137] Referring to FIG. 12, at least a portion of the anode-free portion (12a) of the anode plate (12) of the electrode assembly (10') is divided into a plurality of segments (12c). The segments (12c) may be notched in a direction along the short side of the anode current collector of the anode plate (12). For example, the segments (12c) may be notched with a laser. Alternatively, the segments (12c) may be formed by known metal foil cutting processes such as ultrasonic cutting or stamping. Each of the plurality of segments (12c) may have a square, trapezoidal, triangular, parallelogram, semicircular, or semi-elliptical structure.

[0138] The positive electrode unoccupied portion (12a) may include a core-side unoccupied portion adjacent to the winding center of the electrode assembly (10'), an outer-side unoccupied portion adjacent to the outer-side of the electrode assembly (10'), and an intermediate unoccupied portion interposed between the core-side unoccupied portion and the outer-side unoccupied portion, and the segmented portion (12c) may be formed in the intermediate unoccupied portion. The core-side unoccupied portion and the outer-side unoccupied portion may not have segmented portions formed therein. The height (length in the Z-axis direction) of the positive electrode unoccupied portion (12a) is not constant and may have relative differences in the winding direction. For example, the height of the outer-side unoccupied portion may be relatively smaller than that of the core-side unoccupied portion and the intermediate unoccupied portion. Also, the height of the intermediate unoccupied portion may have a step shape that increases stepwise from the core side to the outer-side. The width (length in the X-direction) of the core-side unoccupied portion may be designed by applying a condition that does not obscure the cavity (H1) of the electrode assembly (10') when the segmented portions (12c) of the intermediate unoccupied portion are folded toward the core side. In this way, by forming segments (12c) while adjusting the height and length of other unsegmented sections where segments (12c) are not formed, the cavity (H1) of the electrode assembly (10') is prevented from being blocked when the anode unsegmented section (12a) is bent, thereby allowing the electrolyte injection process and welding process to proceed easily.

[0139] The plurality of segments (12c) can be bent toward the core side of the electrode assembly (10'). At this time, the plurality of segments (12c) can be overlapped in multiple layers along the radial direction of the electrode assembly (10'). By forming and bending the plurality of segments (12c) in this manner, there is no risk that the unbent portion will not bend properly compared to the case where they are not bent. If the unbent portion does not bend properly, the separator is exposed between the unbent portions, and a problem arises in which the separator is damaged by a high-energy laser during laser welding.

[0140] Meanwhile, at least a portion of the negative electrode unoccupied section (14a) may also be divided into multiple segments. All details regarding the segments or bending of the negative electrode unoccupied section (14a) can be applied exactly as described in the positive electrode unoccupied section (12a).

[0141] FIG. 13 is a cross-sectional view of a cylindrical secondary battery including the electrode assembly of FIG. 12.

[0142] Referring to FIG. 13, the cylindrical secondary battery (100') is identical to the cylindrical secondary battery (100) of FIG. 11 except that it includes the electrode assembly (10') of FIG. 12. In the cylindrical secondary battery (100'), the only difference is that the negative electrode collector plate hole in the center of the negative electrode collector plate (140) is given the reference numeral H2.

[0143] In this cylindrical secondary battery (100'), the positive electrode unoccupied portion (12a) and the negative electrode unoccupied portion (14a) have a folded shape. As a result, the space occupied by each unoccupied portion (12a, 14a) is reduced, which can lead to an improvement in energy density. In addition, the increase in the bonding area between each unoccupied portion (12a, 14a) and each current collector plate (120, 140) can lead to an improvement in bonding strength and a reduction in resistance.

[0144] Now, various embodiments of the positive electrode collector plate (120) and the negative electrode collector plate (140) will be described. In a cylindrical secondary battery (100, 100'), the bonding area (S1) between the positive electrode non-positive portion (12a) and the positive electrode collector plate (120) is smaller than the bonding area (S2) between the negative electrode non-positive portion (14a) and the negative electrode collector plate (140). S1 <S2인 관계를 만족할 때에 양극과 음극간 키네틱 밸런스를 맞출 수 있다. 아래 설명하는 양극 집전판(120)과 음극 집전판(140)은 S1<S2인 관계를 만족시키는 것이다.

[0145] First, Figures 14 to 17 are drawings showing various forms of positive current collector plates.

[0146] Referring to FIGS. 14 to 17, the positive current collector plate (120) includes a rim portion (121), a positive tab connecting portion (122), and a terminal connecting portion (123). The rim portion (121), the positive tab connecting portion (122), and the terminal connecting portion (123) may all be located within the same plane. That is, the positive current collector plate (120) is a roughly plate-shaped member having a thickness smaller than the width or length of the portion having a large area, and when the portion having a large area of ​​the positive current collector plate (120) is placed on the top of the electrode assembly (10, 10'), the entire positive current collector plate (120) has a shape that extends parallel to the top surface of the electrode assembly (10, 10'), and there is no height difference between the rim portion (121), the positive tab connecting portion (122), and the terminal connecting portion (123) within the positive current collector plate (120). This flat structure does not take up much volume within the battery can (110), so it offers good space utilization.

[0147] The rim portion (121) may have a roughly rim shape with a void space (S) formed in at least a part of the inner area. Although the drawings only show the rim portion (121) having a roughly circular rim shape, the present invention is not limited thereto. The rim portion (121) may have a roughly square rim shape or other shapes, unlike what is shown.

[0148] The positive tab connecting portion (122) extends inward from the edge portion (121) and is welded to the positive non-positive portion (12a). The positive tab connecting portion (122) can also be seen as a strip as described with reference to FIG. 5. The terminal connecting portion (123) is spaced apart from the positive tab connecting portion (122) and is located on the inner side of the edge portion (121). The terminal connecting portion (123) can be joined by welding to the previously described rivet terminal (130). The terminal connecting portion (123) can be located, for example, at the center of the inner space of the edge portion (121). The terminal connecting portion (123) can be positioned at a location corresponding to the cavity (H1) formed at the center of the winding of the electrode assembly (10, 10').

[0149] The positive tab coupling portion (122) and the terminal coupling portion (123) are arranged to be spaced apart from each other and are not directly connected, but are electrically connected by the rim portion (121). In this way, the positive current collector plate (120) has a structure in which the positive tab coupling portion (122) and the terminal coupling portion (123) are not directly connected to each other but are connected through the rim portion (121), thereby dispersing the impact applied to the coupling portion between the positive tab coupling portion (122) and the positive non-positive portion (12a) and the coupling portion between the terminal coupling portion (123) and the rivet terminal (130) when an impact and / or vibration occurs in the cylindrical secondary battery (100, 100'). Therefore, the positive current collector plate (120) also has the effect of minimizing or preventing damage to the welded portion due to external impact. The positive current collector plate (120) has a structure in which stress can be concentrated at the connection point between the edge portion (121) and the terminal connection portion (123) when an external impact is applied. Since this connection point is not a part where a weld is formed for joining parts, it is possible to prevent product defects caused by damage to the weld due to an external impact. As such, the positive current collector plate (120) has a structure that prevents force from being concentrated at the connection point between parts even when an external impact and / or vibration is applied during use, thereby improving the performance of the cylindrical secondary battery (100, 100') including it.

[0150] The positive current collector plate (120) may further include a connecting portion (124) that extends inward from the edge portion (121) and is connected to the terminal connecting portion (123). At least a portion of the connecting portion (124) may be formed with a width smaller than that of the positive tab connecting portion (122). In this case, the electrical resistance increases in the connecting portion (124), so that when current flows through the connecting portion (124), a greater resistance occurs compared to other parts, and as a result, when an overcurrent occurs, a portion of the connecting portion (124) breaks, thereby blocking the overcurrent. The width of the connecting portion (124) may be adjusted to an appropriate level in consideration of this overcurrent blocking function. At least a portion of the connecting portion (124) may have a relatively narrow width to enhance the current blocking function.

[0151] The connecting portion (124) may include a tapered portion (124a) whose width gradually narrows along the direction from the inner surface of the edge portion (121) toward the terminal connecting 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 edge portion (121) can be improved.

[0152] A plurality of positive tab coupling portions (122) may be included in the positive current collector plate (120). A plurality of positive tab coupling portions (122) may be arranged at equal intervals along the circumferential direction. The extension length of each of the plurality of positive tab coupling portions (122) may be equal to each other. A terminal coupling portion (123) may be arranged to be surrounded by a plurality of positive tab coupling portions (122). A connecting portion (124) may be located between a pair of adjacent positive tab coupling portions (122). In this case, the distance from the connecting portion (124) to one of the pair of positive tab coupling portions (122) along the direction along the edge portion (121) may be equal to the distance from the connecting portion (124) to the other of the pair of positive tab coupling portions (122) along the direction along the edge portion (121).

[0153] Multiple connecting parts (124) may be included. Each of the multiple connecting parts (124) may be positioned between a pair of adjacent positive tab connecting parts (122). The multiple connecting parts (124) may be positioned at equal intervals along the circumferential direction.

[0154] As described above, in the case where a plurality of positive tab coupling parts (122) and / or connecting parts (124) are included, if the distance between the positive tab coupling parts (122) and / or the distance between the connecting parts (124) and / or the distance between the positive tab coupling parts (122) and the connecting parts (124) is formed to be constant, the flow of current from the positive tab coupling parts (122) toward the connecting parts (124) or the flow of current from the connecting parts (124) toward the positive tab coupling parts (122) can be formed smoothly.

[0155] The positive tab connecting portion (122) can be welded over a certain area while seated on the folded surface of the positive non-positive portion (12a) in the electrode assembly (10'). That is, the positive tab connecting portion (122) can be connected to an area where multiple segments (12c in FIG. 12) are superimposed in multiple layers. A positive weld can be formed for each positive tab connecting portion (122). Through the positive weld in the positive tab connecting portion (122), a connection area (S1) between the positive non-positive portion (12a) and the positive current collector plate (120) is secured. The positive weld can be formed by extending along the extension direction of the positive tab connecting portion (122).

[0156] In FIGS. 14, 15 and 17, the number of positive tab connecting parts (122) is 4, and in FIG. 16, the number of positive tab connecting parts (122) is 3. The number of positive tab connecting parts (122) may vary, and the connecting area (S1) between the positive non-positive part (12a) and the positive current collector plate (120) may vary by adjusting the number of positive tab connecting parts (122) and the number and area of ​​the positive welding parts.

[0157] FIGS. 18 to 25 are drawings showing various forms of cathode current collector plates.

[0158] First, referring to FIGS. 18 to 21, the negative electrode collector plate (140) includes at least one negative electrode tab coupling portion (142) coupled to the negative electrode non-coupling portion (14a) and at least one can coupling portion (143) extending from the negative electrode tab coupling portion (142) and electrically coupled to the beading portion (112) on the inner surface of the battery can (110). The negative electrode tab coupling portion (142) and the can coupling portion (143) may not be in the same plane. That is, the negative electrode collector plate (140) is a roughly plate-shaped member having a thickness smaller than the width or length of the portion having a large area, and when the portion having a large area of ​​the negative electrode collector plate (140) is placed at the bottom of the electrode assembly (10, 10'), there is a height difference between the negative electrode tab coupling portion (142) and the can coupling portion (143) within the negative electrode collector plate (140). This three-dimensional structure can improve the bonding strength of the bonding portion with the battery can (110) by ensuring a contact area between the negative electrode tab coupling portion (142) and the negative electrode non-coupling portion (14a), while allowing the can coupling portion (143) to be raised upward and fixed to the beading portion (112) of the battery can (110).

[0159] The center (141) of the cathode collector plate (140) may have a roughly circular plate shape. The center (141) may optionally be combined with the cathode non-recycled portion (14a). The center (141) may have a ring-shaped plate shape with a cathode collector plate hole (H2) provided in its center.

[0160] The negative electrode collector plate hole (H2) may be 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 electrode collector plate hole (H2) communicating with each other may function as a passage for inserting a welding rod for welding between the rivet terminal (130) and the positive electrode collector plate (120) or for irradiating a laser welding beam.

[0161] The diameter of the negative electrode collector plate hole (H2) may be equal to or larger than the diameter of the cavity (H1) of the electrode assembly (10'). Preferably, if the diameter of the negative electrode collector plate hole (H2) is set larger than the diameter of the cavity (H1) of the electrode assembly (10'), it becomes easier to secure space for inserting a welding guide when inserting a welding rod or irradiating a laser welding beam for welding between the rivet terminal (130) and the positive electrode collector plate (120).

[0162] The center (141) and the negative tab coupling portion (142) are positioned at the bottom 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).

[0163] The negative electrode collector plate (140) may have at least one leg structure extending along the radial direction in a state where the negative electrode tab coupling portion (142) and the can coupling portion (143) are interconnected. Preferably, the leg structure may be provided in multiple numbers. For example, referring to FIGS. 18 to 20, the negative electrode collector plate (140) may have four leg structures. Referring to FIG. 21, the negative electrode collector plate (140) may have six leg structures. When multiple leg structures are provided in this manner, multiple can coupling portions (143) may also be provided. At this time, although not shown in the drawings, multiple can coupling portions (143) may be interconnected and formed as a single unit.

[0164] The negative tab connecting portion (142) may have a shape that extends approximately radially from the center (141) of the negative electrode collector plate (140) toward the side wall of the battery can (110). For example, a plurality of negative tab connecting portions (142) may be provided. Each of the plurality of negative tab connecting portions (142) may be positioned spaced apart from one another along the circumference of the center (141). The negative tab connecting portion (142) may also be viewed as a strip as described with reference to FIG. 5. By providing a plurality of negative tab connecting portions (142), the connecting area with the negative electrode non-part (14a) can be increased. Accordingly, the connecting force between the negative electrode non-part (14a) and the negative tab connecting portion (142) can be secured and the electrical resistance can be reduced.

[0165] The cathode tab connecting portion (142) can be welded to the cathode non-connecting portion (14a). Welding can be performed on a certain area while the cathode tab connecting portion (142) is seated on the folded surface of the cathode non-connecting portion (14a) in the electrode assembly (10'). That is, the cathode tab connecting portion (142) can be connected to an area where multiple segments are superimposed in multiple layers. A cathode weld can be formed for each cathode tab connecting portion (142). Through the cathode weld in the cathode tab connecting portion (142), a connection area (S2) between the cathode non-connecting portion (14a) and the cathode current collector plate (140) is secured. The cathode weld can be formed extending along the extension direction of the cathode tab connecting portion (142).

[0166] The longitudinal end of the negative tab coupling portion (142) may be located further inward than the innermost point of the beading portion (112) formed on the battery can (110). More specifically, the boundary area between the negative tab coupling portion (142) and the can coupling portion (143) may be located further inward in the direction toward the cavity (H1) of the electrode assembly (10, 10') than the innermost point of the beading portion (112) formed on the battery can (110). With such a structure, damage to the coupling portion between parts that may occur when the negative electrode collector plate (140) is excessively bent to position the end of the can coupling portion (143) on the beading portion (112) can be prevented.

[0167] The can coupling portion (143) may be connected to the beading portion (112) on the inner surface of the battery can (110) by extending from the end of the negative tab coupling portion (142). For example, the can coupling portion (143) may have a shape that extends from the end of the negative tab coupling portion (142) toward the side wall of the battery can (110). For example, a plurality of can coupling portions (143) may be provided. Each of the plurality of can coupling portions (143) may be spaced apart from one another along the circumference of the center (141). As illustrated in FIGS. 11 and 13, the plurality of can coupling portions (143) may be connected to the beading portion (112) on the inner surface of the battery can (110). In addition, by a structure in which the negative electrode collector plate (140) is coupled to the beading portion (112) of the battery can (110) rather than the inner surface of the cylindrical portion of the battery can (110), the distance between the negative electrode collector plate (140) and the beading portion (112) can be reduced. Accordingly, the dead space inside the battery can (110) is minimized, and the energy density of the cylindrical secondary battery (100, 100') can be improved.

[0168] The can coupling portion (143) can be compressed and fixed by the crimping portion (114) of the battery can (110). The can coupling portion (143) may include a contact portion (143a) coupled to the beading portion (112) on the inner surface of the battery can (110), and a connecting portion (143b) connecting the negative tab coupling portion (142) and the contact portion (143a).

[0169] The contact portion (143a) is coupled to the inner surface of the battery can (110). In the case where a beading portion (112) is formed on the battery can (110), the contact portion (143a) may be coupled to the beading portion (112). In this case, as described above, for stable contact and coupling, both the beading portion (112) and the contact portion (143a) may have a shape that extends along a direction approximately parallel to the lower surface of the battery can (110), that is, a direction approximately perpendicular to the side wall of the battery can (110). That is, the contact portion (143a) includes at least a portion of a flat portion approximately parallel to the lower surface of the battery can (110).

[0170] As shown in FIG. 18, the connecting portion (143b) may have at least one bending portion (B) in which the extension direction between the center (141) and the contact portion (143a) changes at least once. That is, the connecting portion (143b) may have 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 bending portion (B). The structure of such a connecting portion (143b) allows the contact portion (143a) to be in close contact with the beading portion (112) during the process of accommodating the electrode assembly (10, 10') combined with the negative electrode collector plate (140) into the battery can (110), even if there is a height variation of the electrode assembly (10, 10') within a certain range. In addition, according to the structure of this connecting part (143b), the shape can be implemented more stably during the sizing process. The sizing process is a compression process for reducing the height occupied by the beading part (112) of the battery can (110) in order to reduce the total height of the cylindrical secondary battery (100, 100') when manufacturing the cylindrical secondary battery (100, 100'). In addition, the contractible and expandable structure of the connecting part (143b) allows the shock caused by the movement of the electrode assembly (10, 10') to be mitigated within a certain range, even if the electrode assembly (10, 10') moves up and down due to vibration and / or shock during the use of the cylindrical secondary battery (100, 100').

[0171] The shape of the contact portion (143a) and the connection portion (143b) can be varied. The negative electrode collector plate (140) of FIG. 18 and the negative electrode collector plate (140) of FIG. 19 differ only in the shape of the contact portion (143a), but otherwise, the structure of the negative electrode collector plate (140) described above can be applied substantially identically.

[0172] Referring to FIG. 19, the contact portion (143a) may have a shape in which at least a portion extends along the inner circumference of the battery can (110). For example, the contact portion (143a) may have an arc shape that extends along the beading portion of the battery can (110). Additionally, although not shown in the drawing, to maximize the contact area, the negative electrode current collector (140) may be configured such that the sum of the extended lengths of the contact portions (143a) of each of at least one can coupling portion (143) is approximately equal to the inner circumference of the battery can (110). In such an embodiment, the effect of improved coupling strength and reduced electrical resistance due to the maximization of the coupling area may be achieved.

[0173] Next, referring to FIG. 20, the negative current collector plate (140) of FIG. 20 differs from the negative current collector plate (140) of FIG. 19 only in the shape of the contact portion (143a) and the connection portion (143b), except that the structure of the negative current collector plate (140) described above can be applied substantially identically.

[0174] Referring to FIG. 20, the connecting portion (143b) may have a shape in which at least a portion extends along the inner surface of the battery can (110). Specifically, the contact portion (143a) may have an arc shape extending along the beading portion of the battery can (110), and the connecting portion (143b) may have an arc shape extending along the contact portion (143a). With such a structure, the area of ​​the negative electrode collector plate (140) is additionally increased compared to the negative electrode collector plate (140) shown in FIG. 20, so the effect of reducing electrical resistance can be maximized.

[0175] As shown in FIGS. 18, 19, and 21, the connection portion between the contact portion (143a) and the connection portion (143b) may be bent. Alternatively, as shown in FIG. 20, the connection portion between the contact portion (143a) and the connection portion (143b) may have a complementary shape corresponding to the inner surface of the beading portion (112). In particular, the connection portion between the contact portion (143a) and the connection portion (143b) may be joined to the beading portion (112) without gaps while having a shape that matches the inner surface of the beading portion (112). According to such a structure, the beading portion (112) can effectively support the negative electrode collector plate (140). Furthermore, according to such a structure, unnecessary interference between the beading portion (112) and the connection portion (143b) can be prevented. Therefore, a stable connection between the contact portion (143a) and the beading portion (112) can be effectively maintained.

[0176] Meanwhile, referring to FIG. 20, the negative electrode collector plate (140) may not have a bending portion (B), unlike the negative electrode collector plate (140) shown in FIG. 18, FIG. 19 and FIG. 21. If the bending portion (B) is not provided in this way, the raw materials required for manufacturing the negative electrode collector plate (140) can be reduced. Accordingly, the manufacturing cost of the negative electrode collector plate (140) can be saved.

[0177] Meanwhile, the contact portion (143a) can be interposed and fixed between the beading portion (112) of the battery can (110) and the sealing gasket (180). That is, the contact portion (143a) can be fixed by the crimping force of the crimping portion (114) while the contact portion (143a) is interposed between the beading portion (112) of the battery can (110) and the sealing gasket (180).

[0178] According to one embodiment of the present invention, the circumferential length of the contact portion (143a) may be the same as the circumferential length of the cathode tab coupling portion (142). Additionally, 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 FIGS. 21, it can be seen that the cathode tab coupling portion (142), the connecting portion (143b), and the contact portion (143a) are extended with the same width.

[0179] According to another embodiment of the present invention, the circumferential length of the contact portion (143a) may be formed to be relatively longer than the circumferential length of the cathode tab coupling portion (142). Additionally, preferably, the circumferential length of the contact portion (143a) may be formed to be relatively longer than the circumferential length of the connecting portion (143b). For example, referring to FIGS. 19 and FIGS. 20, it can be seen that the circumferential length of the contact portion (143a) is formed to be relatively longer than the circumferential length of the cathode tab coupling portion (142). Also, referring to FIG. 19, it can be seen that the circumferential length of the contact portion (143a) is formed to be 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 way, the bonding strength with the beading portion (112) of the cathode current collector plate (140) can be improved. Furthermore, the internal resistance of the battery can be reduced by forming the circumferential length of the contact portion (143a) and / or the connection portion (143b) longer.

[0180] In FIGS. 18 to 20, the number of cathode tab connecting portions (142) is 4, and in FIG. 21, the number of cathode tab connecting portions (142) is 6. The number of cathode tab connecting portions (142) in the cathode collector plate (140) may vary, and the connecting area (S2) between the cathode non-connecting portion (14a) and the cathode tab connecting portions (142) may vary by adjusting the number of cathode tab connecting portions (142) and the number and area of ​​the cathode welding portions.

[0181] A cylindrical secondary battery (100, 100') can be implemented with various combinations of the positive electrode current collector (120) exemplified in FIGS. 14 to 17 and the negative electrode current collector (140) exemplified in FIGS. 18 to 21.

[0182] The area of ​​one weld in each current collector plate can be made equal, and the number of welds formed on the positive current collector plate (120) can be reduced so that the combined area (S1) between the positive non-positive portion (12a) and the positive current collector plate (120) is smaller than the combined area (S2) between the negative non-positive portion (14a) and the negative current collector plate (140). When a positive weld is formed at each positive tab joint (122) and a negative weld is formed at each negative tab joint (142), the number of positive tab joints (122) can be made smaller than the number of negative tab joints (142) to satisfy these conditions. Accordingly, the number of negative tab coupling portions (142) of the negative electrode collector plate (140) can be M, and the number of positive tab coupling portions (122) of the positive electrode collector plate (120) can be 1 to M-1 (M is a natural number greater than or equal to 2), and in this case, the ratio of appropriate coupling areas (S1 / S2) between the positive electrode collector plate and the negative electrode collector plate can be adjusted within the range of 1 / M to (M-1) / M.

[0183] The welding process on the positive electrode collector plate (120) and the welding process on the negative electrode collector plate (140) can have the same set conditions applied, such as laser output, irradiation time, and irradiation speed, and applying them in this way is easier in terms of process management than not doing so. In such a case, the area of ​​one positive electrode weld and one negative electrode weld are formed equally. Therefore, it is a preferred embodiment to control 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 on the positive electrode collector plate (120) and the welding process on the negative electrode collector plate (140). In terms of resistance, it is preferable to form a positive electrode weld for each positive electrode tab connection part (122) and a negative electrode weld for each negative electrode tab connection part (142). Therefore, it is a preferred embodiment to control the welding area by making the number of positive electrode tab connection parts (122) smaller than the number of negative electrode tab connection parts (142).

[0184] For example, a combination of an anode current collector (120) having four anode tab coupling portions (122) as exemplified in FIGS. 14 to 17 and a cathode current collector (140) having six cathode tab coupling portions (142) as exemplified in FIG. 21 may be used. As another example, a combination of an anode current collector (120) having three anode tab coupling portions (122) as exemplified in FIG. 16 and a cathode current collector (140) having four cathode tab coupling portions (142) as exemplified in FIG. 18 to 21 may be used.

[0185] Of course, as another example, in order to make the bonding area (S1) between the positive electrode unbonded portion (12a) and the positive electrode collector plate (120) smaller than the bonding area (S2) between the negative electrode unbonded portion (14a) and the negative electrode collector plate (140), it is possible to make the area of ​​one weld formed on the positive electrode collector plate (120) smaller, even though the number of welds on each collector plate is the same.

[0186] Next, referring to FIGS. 22 to 25, a deformed cathode collector plate (140) is shown compared with the cathode collector plate (140) shown in FIGS. 18 to 21.

[0187] Referring to FIG. 22, the cathode collector plate (140) of FIG. 22 differs from the cathode collector plate (140) of FIG. 18 only in that the cathode tab coupling part (142) and the can coupling part (143) are not directly connected to each other, unlike the cathode collector plate (140) of FIG. 18 in which the can coupling part (143) extends from the cathode tab coupling part (142), and otherwise, the structure of the cathode collector plate (140) described above can be applied substantially the same way.

[0188] In the negative electrode collector plate (140) of FIG. 22, the negative electrode tab coupling portion (142) and the can coupling portion (143) are indirectly connected through the center (141) and are not directly connected to each other. Therefore, when an external impact is applied to the cylindrical secondary battery (100, 100') of the present invention, the possibility of damage occurring to the coupling portion between the negative electrode collector plate (140') and the electrode assembly (10, 10') and the coupling portion between the negative electrode collector plate (140') and the battery can (110) can be minimized.

[0189] Next, referring to FIG. 23, the negative electrode collector plate (140) of FIG. 23 differs from the negative electrode collector plate (140) described earlier with reference to FIG. 22 only in the shape of its contact portion (143a), except that the structure of the negative electrode collector plate (140) of FIG. 18 and FIG. 22 described earlier can be applied substantially identically. In addition, the contact portion (143a) of the negative electrode collector plate (140) of FIG. 23 has a shape that extends along the inner circumference of the battery can (110), and the description for this is the same as the description of the negative electrode collector plate (140) described with reference to FIG. 19.

[0190] Referring to FIG. 24, the cathode collector plate (140) of FIG. 24 differs from the cathode collector plate (140) described earlier with reference to FIG. 22 only in that it includes an additional can coupling portion (144), otherwise, the structure of the cathode collector plate (140) of FIG. 18 and FIG. 22 described earlier can be applied substantially identically.

[0191] An additional can coupling portion (144) extends from the end of the negative tab coupling portion (142) and is coupled to the inner surface of the battery can (110). At least one end of a plurality of negative tab coupling portions (142) is provided with such an additional can coupling portion (144). The additional can coupling portion (144) includes an additional contact portion (144a) coupled to the inner surface of the battery can (110) and an additional connection portion (144b) connecting the end of the negative tab coupling portion (142) and the additional contact portion (144a).

[0192] The additional contact portion (144a) is coupled to the inner surface of the battery can (110). In the case where a beading portion (112) is formed on the battery can (110), the additional contact portion (144a) may be coupled to the beading portion (112) in the same way as the contact portion (143a). Also, like the shape of the contact portion (143a) shown in FIG. 23, the additional contact portion (144a) may also have a shape in which at least a portion extends along the inner circumference of the battery can (110).

[0193] The additional connecting portion (144b) may have at least one bending portion in which the extension direction is switched at least once between the negative tab connecting portion (142) and the additional contact portion (144a), similar to the connecting portion (143b) described earlier with reference to FIG. 18. As previously described, the additional connecting portion (144b) has a structure capable of contracting and expanding due to the formation of the bending portion, and thus has advantages in the assembly process of the cylindrical secondary battery (100, 100') and a buffering effect.

[0194] Referring to FIG. 25, the negative electrode current collector (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). In the case where multiple negative electrode tab coupling portions (142) are provided, the liquid injection hole (H3) may be provided in at least one negative electrode tab coupling portion (142). The liquid injection hole (H3) may be provided, for example, on one side of the negative electrode weld portion (W) formed on the negative electrode tab coupling portion (142) or on both sides. In manufacturing a cylindrical secondary battery (100, 100'), an assembly including an electrode assembly (10, 10') and a negative electrode current collector (140) may be housed in a battery can (110), and then an electrolyte may be injected. At this time, the liquid injection performance may be improved due to the liquid injection hole (H3).

[0195] Multiple injection holes (H3) may be provided. Multiple injection holes (H3) may be arranged approximately symmetrically to the left and right with respect to the center of the width direction of the cathode tab coupling part (142). Between the injection holes (H3) arranged approximately symmetrically to the left and right, a cathode welding part (W) for coupling the cathode tab coupling part (142) and the cathode non-coupling part (14a) may be formed.

[0196] The negative tab coupling portion (142) may be formed such that the width at a position spaced a predetermined distance from the connection portion toward the longitudinal end of the tab coupling portion is greater than the width at the connection portion between the negative tab coupling portion (142) and the center (141). At least a portion of the area where the injection hole (H3) is formed may be included in an area that has been expanded by increasing the width at a position spaced a predetermined distance from the connection portion toward the end of the negative tab coupling portion (142) compared to the width at the connection portion between the negative tab coupling portion (142) and the center (141). Meanwhile, the longitudinal end of the negative tab coupling portion (142) may have a roughly arc shape to correspond to the inner circumference of the battery can (110). Furthermore, the description regarding the structure of the negative current collector plate (140) of FIG. 25 may be applied as described above with reference to FIG. 18, FIG. 19, FIG. 22, FIG. 23, etc.

[0197] A cylindrical secondary battery (100, 100') may also be implemented with various combinations of the positive electrode current collector (120) exemplified in FIGS. 14 to 17 and the negative electrode current collector (140) exemplified in FIGS. 22 to 25.

[0198] The area of ​​one weld in each current collector plate can be made equal, and the number of welds formed on the positive current collector plate (120) can be reduced so that the combined area (S1) between the positive non-positive portion (12a) and the positive current collector plate (120) is smaller than the combined area (S2) between the negative non-positive portion (14a) and the negative current collector plate (140). When a positive weld is formed at each positive tab joint (122) and a negative weld is formed at each negative tab joint (142), the number of positive tab joints (122) can be made smaller than the number of negative tab joints (142) to satisfy these conditions.

[0199] For example, a combination of an anode current collector plate (120) having three anode tab coupling portions (122) as shown in FIG. 16 and a cathode current collector plate (140) having four cathode tab coupling portions (142) as shown in FIG. 22 to FIG. 25 can be used.

[0200] Referring to FIG. 26, a battery pack (200) according to one embodiment of the present invention comprises a secondary battery assembly in which a plurality of cylindrical secondary batteries (100) according to one embodiment of the present invention as described above are electrically connected, and a pack housing (210) that accommodates the same. For convenience of illustration, components such as a busbar for electrical connection, a cooling unit, and a power terminal have been omitted in the drawings of the present invention.

[0201] Referring to FIG. 27, a vehicle (300) according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack (200) according to one embodiment of the present invention. The vehicle (300) includes four-wheeled vehicles and two-wheeled vehicles. The vehicle (300) operates by receiving power from the battery pack (200) according to one embodiment of the present invention.

[0202] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0203] 10, 10': Electrode assembly 12: Positive plate 14: Cathode plate 16: Separator 12a: Positive indeterminate region 12b: Positive active material layer 12c: segment 14a: Cathode inert region 14b: Cathode active material layer 20, 100, 100': Cylindrical secondary battery 22, 120: Positive current collector 22a: Anode weld 22b, 24b: Strip 24, 140: Cathode current collector 24a: Cathode weld 110: Battery can 112: Bidding Department 114: Creaming Department 121: Border 122: Positive tab connection 123: Terminal connection part 130: Rivet terminal 142: Cathode tab connection 143: Can joint 143a: Contact part 143b: Connection 150: Insulator 160: Insulating gasket 170: Cap Plate 180: Sealing gasket 190: Bentling Department H1: Joint H2: Cathode collector plate hole H3: Injection hole 200: Battery pack 300: Car

Claims

Claim 1 A jelly-roll type electrode assembly having a structure in which an anode plate and a cathode plate having a sheet shape and a separator interposed between them are wound in one direction, wherein the anode plate includes an anode non-positive portion exposed to the outside of the separator at the long end and the cathode plate includes a cathode non-positive portion exposed to the outside of the separator at the long end; an anode current collector plate joined by the anode non-positive portion and the anode welded portion; and a cathode current collector plate joined by the cathode non-positive portion and the cathode welded portion, wherein the combined area (S1) between the anode non-positive portion and the anode current collector plate is smaller than the combined area (S2) between the cathode non-positive portion and the cathode current collector plate. Claim 2 A secondary battery according to claim 1, characterized in that at least a portion of the positive electrode non-existent part is used as a positive electrode tab itself, and at least a portion of the negative electrode non-existent part is used as a negative electrode tab itself. Claim 3 A secondary battery according to claim 1, wherein the positive electrode blank portion or the negative electrode blank portion is bent along the radial direction of the electrode assembly. Claim 4 A secondary battery according to claim 1, characterized in that at least a portion of the positive electrode unoccupied portion or the negative electrode unoccupied portion is divided into a plurality of segments. Claim 5 A secondary battery according to claim 4, characterized in that the plurality of segments are bent along the radial direction of the electrode assembly and overlapped in multiple layers. Claim 6 A secondary battery according to claim 4, wherein the unsold portion having a plurality of segments formed therein comprises a core-side unsold portion adjacent to the winding center of the electrode assembly, an outer-side unsold portion adjacent to the outer-side of the electrode assembly, and an intermediate unsold portion interposed between the core-side unsold portion and the outer-side unsold portion, wherein the plurality of segments are formed in the intermediate unsold portion. Claim 7 A secondary battery characterized in that, in claim 6, the segmented portion is not formed on the core-side unoccupied portion. Claim 8 A secondary battery characterized in that, in claim 6, the height of the outer circumference unoccupied portion is smaller than the height of the core side unoccupied portion and the intermediate unoccupied portion. Claim 9 A secondary battery characterized in that, in claim 6, the height of the intermediate non-removable portion increases stepwise from the core side to the outer periphery side of the electrode assembly. Claim 10 A secondary battery according to claim 6, wherein the electrode assembly includes a cavity in the center of the winding, and the width of the core-side unwound portion is set so as not to cover the cavity when the plurality of segmented pieces are bent. Claim 11 A secondary battery according to claim 1, wherein at least a portion of the positive electrode non-positive portion is divided into a plurality of segments, the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the positive electrode current collector is seated on the folded surface of the positive electrode non-positive portion and welded to the area where the plurality of segments overlap in multiple layers. Claim 12 A secondary battery according to claim 1, wherein at least a portion of the negative electrode non-part is divided into a plurality of segments, the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the negative electrode current collector is seated on the folded surface of the negative electrode non-part and welded to the area where the plurality of segments overlap in multiple layers. Claim 13 A secondary battery according to claim 1, wherein the positive electrode current collector covers the upper end of the electrode assembly and the negative electrode current collector covers the lower end of the electrode assembly, wherein the positive electrode current collector includes one or more strips extending along the radial direction of the electrode assembly from the center of the positive electrode current collector and the positive weld is formed on the strip of the positive electrode current collector, and the negative electrode current collector includes one or more strips extending along the radial direction of the electrode assembly from the center of the negative electrode current collector and the negative weld is formed on the strip of the negative electrode current collector. Claim 14 A secondary battery according to claim 13, characterized in that the number of strips of the positive electrode current collector is smaller than the number of strips of the negative electrode current collector. Claim 15 A secondary battery according to claim 13, characterized in that the number of positive electrode welds is smaller than the number of negative electrode welds. Claim 16 A secondary battery according to claim 1, characterized in that the number of positive electrode welds and the number of negative electrode welds are equal to each other, and the area of ​​one positive electrode weld is smaller than the area of ​​one negative electrode weld. Claim 17 The secondary battery according to claim 1, further comprising: a battery can accommodating the electrode assembly; a cap plate sealing the opening of the battery can; and a rivet terminal installed in a through hole of the battery can. Claim 18 A secondary battery according to claim 17, wherein the battery can includes an opening on one side, the closing part of the battery can located opposite the opening part and the side part of the battery can are integrally formed, and the rivet terminal is fixed on the inner surface of the closing part by riveting. Claim 19 A secondary battery according to claim 17, wherein the positive current collector plate comprises: a rim portion; a positive tab coupling portion extending inwardly from the rim portion and coupled by the positive non-positive portion and the positive welding portion; and a terminal coupling portion positioned spaced apart from the positive tab coupling portion. Claim 20 In claim 18, the secondary battery further comprises an insulator interposed between the closure portion and the positive current collector plate, and the rivet terminal penetrates the insulator and is coupled to the positive current collector plate. Claim 21 A secondary battery according to claim 19, characterized in that the rivet terminal and the terminal joint are joined by welding. Claim 22 A secondary battery according to claim 19, wherein the rim portion has a rim shape in which at least a portion of the inner region is empty, and the positive tab coupling portion and the terminal coupling portion are electrically connected by the rim portion. Claim 23 A secondary battery according to claim 19, wherein the positive tab coupling portions are a plurality and are arranged at equal intervals along the circumferential direction, and the terminal coupling portions are arranged to be surrounded by the plurality of positive tab coupling portions. Claim 24 A secondary battery according to claim 19, wherein the electrode assembly includes a cavity in the center of the winding, and the terminal coupling portion is positioned at a location corresponding to the cavity. Claim 25 A secondary battery according to claim 19, wherein at least a portion of the positive electrode non-existent portion is divided into a plurality of segments, the plurality of segments are folded along the radial direction of the electrode assembly and overlapped in multiple layers, and the positive electrode tab coupling portion is welded to an area where the plurality of segments overlap in multiple layers on the folded surface of the positive electrode non-existent portion. Claim 26 A secondary battery according to claim 25, characterized in that the positive electrode tab coupling portion is welded while seated on the bent surface of the positive electrode non-coupling portion to form the positive electrode weld portion. Claim 27 A secondary battery according to claim 19, characterized in that the rim portion, positive tab coupling portion, and terminal coupling portion are all located within the same plane. Claim 28 A secondary battery according to claim 1, wherein the negative electrode collector plate includes a negative electrode collector plate hole in the center, the electrode assembly includes a cavity in the center of the winding of the electrode assembly, and the diameter of the negative electrode collector plate hole is equal to or larger than the diameter of the cavity. Claim 29 A secondary battery according to claim 17, wherein at least a portion of the negative electrode non-removable portion is divided into a plurality of segments, and the plurality of segments are bent along the radial direction of the electrode assembly. Claim 30 A secondary battery according to claim 29, wherein the plurality of segments are overlapped in multiple layers along the radial direction of the electrode assembly. Claim 31 A secondary battery according to claim 30, wherein the negative electrode current collector plate comprises a negative electrode tab coupling portion joined by the negative electrode non-coupling portion and the negative electrode welding portion, and the negative electrode tab coupling portion is joined to an area where the plurality of segmented pieces are overlapped in multiple layers. Claim 32 A secondary battery characterized in that, in claim 31, the negative electrode welding portion is formed by welding the negative electrode tab coupling portion while seated on the folded surface of the negative electrode non-coupling portion. Claim 33 A battery pack comprising a secondary battery according to any one of paragraphs 1 to 32. Claim 34 An automobile including a battery pack pursuant to Paragraph 33.

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