Jelly-roll electrode assembly, secondary battary, battary pack and vehicle

Abstract

The present invention relates to a jelly-roll type electrode assembly, a secondary battery, a battery pack, and an automobile, and more specifically, to a jelly-roll type electrode assembly including a separator overlap portion, a cylindrical secondary battery, a battery pack, and an automobile.

Description

Technology Field

[0001] The present invention relates to a jelly-roll type electrode assembly, a secondary battery, a battery pack, and an automobile, and more specifically, to a jelly-roll type electrode assembly including a separator overlap portion, a cylindrical secondary battery, a battery pack, and an automobile. Background Technology

[0002] Secondary batteries, which offer high applicability across product categories and possess electrical characteristics such as high energy density, are widely applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric driving sources.

[0003] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium-polymer batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. The operating voltage of these individual secondary battery cells is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, multiple secondary battery cells are connected in series to form a battery pack. Additionally, depending on the charge / discharge capacity required for the battery pack, multiple secondary battery cells are connected in parallel to form a battery pack. Accordingly, the number of secondary battery cells included in the battery pack and the electrical connection type can be set in various ways depending on the required output voltage and / or charge / discharge capacity.

[0005] Meanwhile, if the form factor is increased to apply cylindrical secondary battery cells to electric vehicles, a problem may arise where the cells ignite due to the significant heat generated during rapid charging. For example, the possibility of deformation of the electrode assembly located in the core increases due to the shrinkage or expansion of the electrode assembly during charging and discharging. Furthermore, if the separator located between the negative and positive electrodes is damaged, the negative and positive electrodes come into direct contact, leading to an internal short circuit that causes heat generation and ignition.

[0006] When the rate of heat generation inside a secondary battery cell due to an internal short circuit exceeds the rate of heat release to the outside of the secondary battery cell, the temperature of the secondary battery cell begins to rise, and the secondary battery cell that has generated heat and ignited acts as an external heat source, which can lead to a rise in the temperature of neighboring secondary battery cells. When the secondary battery cell reaches a critical temperature, thermal decomposition of the components occurs, and the rapid decomposition of the anode material and the rapid exothermic reaction between the electrolyte and the anode material, known as thermal runaway, continue until the reactants are completely depleted.

[0007] If the cap of a secondary battery separates due to a rapid increase in pressure inside a secondary battery cell where thermal runaway has occurred, flammable and toxic gases may be released; if exhaust occurs in the early stages, the thermal runaway may be accelerated by oxygen and moisture in the air; and if unburned electrode assemblies are discharged from the battery case before the exothermic reaction is complete, they may propagate to adjacent cells, causing secondary ignition and explosion.

[0008] In particular, when unburned electrode assemblies are discharged, metals with excellent electrical conductivity can come into contact with different cells and form an external short circuit; therefore, battery modules or battery packs containing multiple secondary battery cells have a problem in which the risk of secondary ignition and explosion increases significantly if the same phenomenon occurs in some of the included secondary battery cells.

[0009] Therefore, there is a need to develop technology that can suppress heat generation and ignition caused by internal short circuits, and prevent the problem of unburned electrode assemblies being discharged from the battery case and propagating to adjacent cells even in the event of thermal runaway. The problem to be solved

[0010] The present invention aims to provide a jelly-roll type electrode assembly, a secondary battery, a battery pack, and an automobile with a modified design of a jelly-roll type electrode assembly.

[0011] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0012] One embodiment of the present invention provides a jelly-roll type electrode assembly in which a cathode; a separator; and an anode are sequentially stacked and wound, wherein the anode comprises a first surface in the direction of the winding axis of the jelly-roll type electrode assembly and a second surface opposite to the first surface, and in the core portion of the electrode assembly, a separator overlap portion is included between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode, and the core portion of the electrode assembly comprises a hollow having a diameter of 5 mm or more and 7.5 mm or less.

[0013] Another embodiment of the present invention provides a secondary battery comprising: the electrode assembly; a positive terminal having a riveting structure; and a sealing body, wherein the electrode assembly is housed inside a battery case, the negative electrode and the battery case are electrically connected, the positive electrode and the positive terminal are electrically connected, and the sealing body seals an open end of the battery case so as to be insulated from the battery case.

[0014] Another embodiment of the present invention provides a battery pack comprising at least one secondary battery and a vehicle comprising at least one battery pack. Effects of the invention

[0015] A jelly-roll type electrode assembly according to one embodiment of the present invention includes a separator overlap portion in which the folding structure of the core separator is modified, thereby preventing damage to the negative electrode and separator from deformation of the electrode assembly caused by shrinkage / expansion of the electrode during battery charging / discharging, and even if damage to the separator occurs, the separator overlap portion prevents an internal short circuit between the positive and negative electrodes, thereby improving battery stability and lifespan characteristics.

[0016] In addition, the secondary battery according to one embodiment of the present invention can improve battery stability and lifespan characteristics by preventing an internal short circuit between the positive and negative electrodes through the separator overlap portion even when the electrode assembly is deformed due to shrinkage / expansion of the electrodes during battery charging / discharging, and can prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to an internal short circuit, etc.

[0017] A battery pack and an automobile according to one embodiment of the present invention suppress heat generation and ignition caused by an internal short circuit of a secondary battery cell, and prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs in each secondary battery cell, thereby improving stability.

[0018] The effects of the present invention are not limited to those described above, and unmentioned effects will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. Brief explanation of the drawing

[0019] FIG. 1 illustrates a jelly-roll type electrode assembly according to one embodiment of the present invention. FIG. 2 schematically illustrates a cross-section and a core portion of a jelly-roll type electrode assembly according to one embodiment of the present invention. FIG. 3 schematically illustrates a core portion including a separator overlap portion of a jelly-roll type electrode assembly according to one embodiment of the present invention. FIG. 4 illustrates a secondary battery according to one embodiment of the present invention. Figure 5 is a cross-sectional view of the secondary battery of Figure 4. FIGS. 6 to 8 are cross-sectional views showing the schematic configuration of a secondary battery according to one embodiment of the present invention. FIG. 9 illustrates an exemplary form of a negative electrode collector plate according to one embodiment of the present invention. FIG. 10 illustrates a battery pack according to one embodiment of the present invention. FIG. 11 illustrates a vehicle according to one embodiment of the present invention. Specific details for implementing the invention

[0020] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0021] Throughout this specification, when a component is described as being located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0023] One embodiment of the present invention is a jelly-roll type electrode assembly in which a cathode; a separator; and an anode are sequentially stacked and wound, wherein the anode comprises a first surface in the direction of the winding axis of the jelly-roll type electrode assembly and a second surface opposite to the first surface.

[0024] A jelly-roll type electrode assembly is provided, wherein the core portion of the electrode assembly includes a separator overlap portion between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode, and the core portion of the electrode assembly includes a hollow having a diameter of 5 mm or more and 7.5 mm or less.

[0025] Here, the 'core portion' is a region including a hollow located on the winding axis of the electrode assembly and a part of the wound stacked structure of the anode / separator / cathode, and may mean a region within 2 turns of the anode from one end in the longitudinal direction of the anode among the stacked structure located at the innermost angle of the electrode assembly.

[0026] A jelly-roll type electrode assembly according to one embodiment of the present invention includes a separator overlap portion in which the folding structure of the core separator is modified, thereby preventing damage to the negative electrode and separator from deformation of the electrode assembly caused by shrinkage / expansion of the electrode during battery charging / discharging, and even if damage to the separator occurs, the separator overlap portion prevents an internal short circuit between the positive and negative electrodes, thereby improving battery stability and lifespan characteristics.

[0027] In addition, the secondary battery according to one embodiment of the present invention can improve battery stability and lifespan characteristics by preventing an internal short circuit between the positive and negative electrodes through the separator overlap portion even when the electrode assembly is deformed due to shrinkage / expansion of the electrodes during battery charging / discharging, and can prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to an internal short circuit, etc.

[0028] FIGS. 1 and FIGS. 2 illustrate a jelly-roll type electrode assembly according to an embodiment of the present invention. Specifically, FIG. 1 illustrates a jelly-roll type electrode assembly according to an embodiment of the present invention, and FIG. 2 schematically illustrates a cross-section and a core portion of a jelly-roll type electrode assembly according to an embodiment of the present invention. More specifically, FIG. 2(a) is a cross-sectional view of the jelly-roll type electrode assembly of FIG. 1, and FIG. 2(b) is a schematic illustration of a core portion including a stepped portion of the electrode assembly.

[0029] According to one embodiment of the present invention, in the core portion of the electrode assembly, the cathode and the separator may be extended further than the longitudinal end of the anode and additionally wound. Specifically, referring to FIGS. 1 and 2, the cathode (110') and the separator (200') may be extended further than the longitudinal end (310e) of the anode and additionally wound. That is, after the winding of the cathode (110') and the separator (200') is completed for a predetermined length, they may be wound together with the anode (310). For example, after the cathode (110') and the separator (200') are wound together around the circumference of the winding core for at least one turn, they may be wound together with the anode (310).

[0030] That is, in the core portion (C) of the jelly-roll type electrode assembly, the longitudinal ends of the cathode (110) and the separator (200) may be located inward from the longitudinal end (310e) of the anode. In other words, the length and width of the cathode may be greater than those of the anode, and the length and width of the separators located on one side and opposite side of the cathode may also be greater than those of the anode.

[0031] When the above-mentioned cathode and separator are extended and additionally wound beyond the longitudinal end of the above-mentioned anode, the transfer of lithium ions from the anode to the cathode in the chemical reaction of the lithium-ion battery may be more facilitated. If the length or width of the cathode is formed wider, the surface area of ​​the cathode receiving lithium ions increases, which can prevent a decrease in charge / discharge efficiency and may result in excellent battery stability and lifespan characteristics.

[0032] According to one embodiment of the present invention, the core portion of the electrode assembly may include a stepped portion, which is an area where the cathode covers the longitudinal end of the anode. Specifically, referring to FIG. 2(b), the stepped portion (400) may refer to an area where the cathode (110) of the core portion (C) covers the longitudinal end (310e) where the winding of the anode begins, that is, an area where a step is formed by the thickness (T) of the longitudinal end of the anode. The stepped portion (400) may be such that the cathode (110) covers the longitudinal end (310e) of the anode, and the space (H3) next to the longitudinal end of the anode is empty due to the thickness (T) of the anode. At this time, the step caused by the thickness of the anode forms stress on the facing cathode, and this stress may be concentrated on the opposite side of the surface facing the anode during charging and discharging, thereby causing a cathode crack.

[0033] In other words, the core portion (C) of the electrode assembly (1000) may have a length of the anode (310) shorter than the remaining layers, and may form an empty space (H3) surrounded by the cathode (110) / longitudinal end (310e) of the anode / cathode (110'). That is, the core portion of the jelly-roll type electrode assembly according to one embodiment of the present invention may include a stepped portion (400) that includes a region forming a stacked structure of cathode (110') / separator (not shown) / anode (310) / separator (not shown) / cathode (110) in a wound state centered on the longitudinal end (310e) of the anode, and a region forming a stacked structure of cathode (110') / separator (not shown) / empty space (H3) / separator (not shown) / cathode (110).

[0034] According to one embodiment of the present invention, the step portion (400) may mean an area centered on the longitudinal end (310e) of the anode, extending from the longitudinal end (310e) of the anode to a point where the cathodes (110, 110') come into direct contact with each other, that is, an area containing a void space (H3) having a predetermined longitudinal length (L1) by the thickness (T) of the anode, and an area containing the anode (310) having the same longitudinal length (L1') as the void space in the opposite direction from the longitudinal end (310e) of the anode. That is, the stepped portion (400) may mean an area having a length of L1+L1'=L1+L1=2L1 centered on the longitudinal end (310e) of the anode, and may mean an area having a longitudinal length of 2L1 from the longitudinal end of the stepped portion (400), that is, the point where the cathodes (110, 110') come into direct contact with each other, toward the longitudinal end (310) of the anode.

[0035] According to one embodiment of the present invention, the core portion of the electrode assembly may include a separator overlap portion between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode. When the separator overlap portion is further included between the anode and the cathode facing the first or second surface of the anode, damage to the cathode and separator that may occur due to the step difference between the anode free edge and the step difference mitigation portion is prevented, and even if damage to the separator occurs, the separator overlap portion prevents an internal short circuit between the anode and the cathode, thereby improving battery stability and lifespan characteristics. Furthermore, even when thermal runaway occurs due to an internal short circuit, the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells can be prevented.

[0036] FIG. 3 schematically illustrates a step section including a separator overlap section of a jelly-roll type electrode assembly according to one embodiment of the present invention. Specifically, FIG. 3(a) schematically illustrates a step section (400) including a separator overlap section (S) provided between an anode (310) and a cathode (110') facing the first surface of the anode, and FIG. 3(b) schematically illustrates a separator overlap section (S) provided between an anode (310) and a cathode (110) facing the second surface of the anode.

[0037] According to one embodiment of the present invention, in the core portion of the electrode assembly, the separator may be extended and additionally wound longer than the longitudinal end of the cathode. Specifically, referring to FIG. 3, by folding back the separator (200') extended and additionally wound from the longitudinal end of the cathode (110') toward the longitudinal end (310e) of the anode, it may be possible to form a separator overlap portion (S) by a simple folding structure without a separate additional separator. That is, the separator overlap portion (S) may include a separator (200) and a separator (200') that is extended, additionally wound, and folded.

[0038] Here, the 'separator overlap portion' is an area extending from the longitudinal end (310e) of the anode to one longitudinal end of the additional overlap separator (200') included in the separator overlap portion (S), and may mean an area having a longitudinal length L2 when the distance between the longitudinal end of the separator overlap portion and the longitudinal end (310e) of the anode is denoted as L2.

[0039] According to one embodiment of the present invention, the separator overlap portion may be provided between the anode and the cathode facing the first surface of the anode. When the separator overlap portion is provided in the direction of the first surface of the anode with respect to the longitudinal end of the anode, damage to the cathode facing the first surface of the anode and the separator can be prevented more effectively.

[0040] According to one embodiment of the present invention, the separator overlap portion may be provided between the anode and the cathode facing the second surface of the anode. When the separator overlap portion is provided in the direction of the second surface of the anode with respect to the longitudinal end of the anode, damage to the cathode facing the second surface of the anode and the separator can be prevented more effectively.

[0041] According to one embodiment of the present invention, the core portion of the electrode assembly may include a hollow having a diameter of 5 mm or more and 7.5 mm or less. Specifically, referring to FIG. 1, the core portion (C) of the electrode assembly (1000) may include a hollow (H1) having a diameter of 5 mm or more and 7 mm or less, 5 mm or more and 6.5 mm or less, 5 mm or more and 6 mm or less, 5.5 mm or more and 7 mm or less, 6 or more and 7 mm or less, or 5.5 mm or more and 6.5 mm or less. For example, the diameter (Φ1) of the core portion hollow (H1) may be 6 mm.

[0042] According to one embodiment of the present invention, the diameter of the core hollow may be 10% or more and 17% or less based on 100% of the cross-sectional diameter of the electrode assembly perpendicular to the winding axis. Specifically, referring to FIG. 2(a), the diameter (Φ1) of the core hollow (H1) may be 10% or more, 10.5% or more, 11% or more, 11.5% or more, 12% or more, or 12.5% ​​or more based on 100% of the cross-sectional diameter (Φ2) of the electrode assembly (1000) perpendicular to the winding axis, and may be 17% or less, 16.5% or less, 16% or less, 15% or less, or 14.5% or less. For example, the diameter (Φ1) of the core hollow (H1) may be about 13% based on 100% of the cross-sectional diameter (Φ2) of the electrode assembly (1000) perpendicular to the winding axis.

[0043] Here, the 'diameter of the core hollow' may refer to the diameter of a virtual circle whose radius is the largest value among the distances from the center of the winding axis of the electrode assembly to the innermost layer in contact with the hollow of the electrode assembly. Additionally, the 'diameter of the cross-section of the electrode assembly perpendicular to the winding axis' may refer to the diameter of a virtual circle whose radius is the smallest value among the distances from the center of the winding axis of the electrode assembly to the outermost layer of the electrode assembly.

[0044] When the diameter of the core is reduced to an appropriate level for winding the electrode assembly, the curvature in the core portion (C) of the jelly-roll type electrode assembly is increased, and the elasticity due to the wound shape of the electrode assembly, that is, the elasticity of the laminate of the electrode and the separator to straighten out again from a bent state, can be further increased.

[0045] This increase in elasticity causes an increase in force applied from the core portion of the electrode assembly toward the outer surface of the electrode assembly, that is, toward the battery case housing the electrode assembly, and this may lead to an increase in frictional force between the negative / separator / positive laminates provided at each different winding turn of the wound electrode assembly.

[0046] When the frictional force between the above laminates increases, the phenomenon of the electrode assembly attempting to unravel from the core portion is reduced, and the phenomenon of the electrode assembly being discharged through the open end of the battery case during thermal runaway—that is, the phenomenon in which discharge from the core portion of the electrode assembly begins due to internal pressure when at least a part of the seal sealing the open end of the battery case is removed—may be suppressed.

[0047] In addition, the frictional force between the laminates may be further increased by including a separator overlap portion between the anode and the cathode facing the first surface of the anode in the core portion of the electrode assembly; or between the anode and the cathode facing the second surface of the anode, and accordingly, even when thermal runaway occurs due to an internal short circuit, the problem of unburned electrode assemblies being discharged from the battery case and propagating to adjacent secondary battery cells can be prevented.

[0048] On the other hand, the above elasticity may decrease when the form factor is increased to apply the manufactured secondary battery to automobiles, etc. Specifically, in the case of a secondary battery with an increased form factor, it may be necessary to secure the rigidity of the winding core to support the increased weight of the electrode assembly, and if the diameter of the winding core is increased to secure the rigidity of the winding core, the diameter of the hollow (H1) of the core part may also increase. As the diameter of the hollow (H1) of the core part increases, the tension of the core part (C) decreases; therefore, when the electrode assembly is housed inside the battery case and the opening of the battery case is sealed with a sealant, a phenomenon in which the core electrode assembly rises may occur. Furthermore, if thermal runaway occurs while the rise of the core electrode assembly is occurring, the time for the electrode assembly to be discharged from the battery case, i.e., the burn duration time, is shortened, and a problem may occur in which an unburned electrode assembly is discharged. Accordingly, the risk of secondary ignition and explosion in adjacent secondary battery cells may increase significantly.

[0049] Here, the 'burn duration time' may refer to the time from the occurrence of a premature lid pop due to internal pressure when at least a part of the seal sealing the opening of the battery case is removed in the event of thermal runaway, until the discharge or finishing of the electrode assembly, and may be judged as a pass if it appears to be more than about 100 ms.

[0050] Accordingly, by adjusting the diameter of the hollow core of the electrode assembly to the aforementioned range, the rigidity of the winding core and the frictional force between the laminates can be adjusted to an appropriate range even in a secondary battery having an increased form factor, and the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells when thermal runaway occurs due to an internal short circuit, etc., can be prevented.

[0051] According to one embodiment of the present invention, the separator overlap portion may have three layers of separators arranged in overlap. If the separator overlap is less than three layers, the effect of preventing damage to the cathode and separator may be inferior, and if it exceeds three layers, stress may be concentrated in the corresponding area due to the formation of additional steps, causing additional damage to the separator, and local problems such as lithium precipitation due to insufficient electrolyte may occur. When the separator arranged in overlap is three layers, a manufacturing process using existing winding equipment is possible without separate equipment modification, making it easier to provide the separator overlap portion.

[0052] According to one embodiment of the present invention, the longitudinal length of the separator overlap portion may be 100% or more and 300% or less based on 100% of the inner circumference of the electrode assembly. Specifically, the longitudinal length of the separator overlap portion may be 100% or more, 150% or more, or 200% or more based on 100% of the inner circumference of the electrode assembly, or 300% or less, 250% or less, or 200% or less, and may be 1 turn or more and 3 turns or less of the inner circumference of the core portion of the electrode assembly. That is, the separator overlap portion may be disposed between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode, with 1 turn or more and 3 turns or less.

[0053] Here, the 'inner surface' may refer to a virtual circle with the largest value among the distances from the winding axis of the electrode assembly to the innermost layer in contact with the hollow of the electrode assembly as the radius, and the 'perimeter of the inner surface' may refer to the circumference of the virtual circle. Additionally, referring to FIG. 3, the longitudinal length (L2) of the separator overlap portion may refer to the distance between the longitudinal end of the separator overlap portion and the longitudinal end (310e) of the anode.

[0054] According to one embodiment of the present invention, the distance between the longitudinal end of the separator overlap portion and the longitudinal end of the anode may be 20 mm or more and 50 mm or less. Specifically, referring to FIG. 3, the distance (L2) between the longitudinal end of the separator overlap portion (S) and the longitudinal end (310e) of the anode may be 20 mm or more, 28 mm or more, or 32 mm or more, and may be 50 mm or less, 44 mm or less, or 38 mm or less. That is, the separator overlap portion may be positioned between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode, at a distance of 20 mm or more and 50 mm or less from the longitudinal end (310e) of the anode.

[0055] If the aforementioned longitudinal length of the separator overlap portion or the range of separation distance between the longitudinal end of the separator overlap portion and the longitudinal end of the anode is satisfied, the frictional force exerted by the separator overlap portion may be sufficient to prevent the problem of unburned electrode assemblies being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to internal short circuits, etc. If the aforementioned longitudinal length range of the separator overlap portion is exceeded, lithium ion transfer may be excessively inhibited by the increased area of ​​the separator overlap portion, and the electrochemical characteristics of the manufactured secondary battery may be inferior. If the aforementioned longitudinal length range of the separator overlap portion is not met, the stability of the manufactured secondary battery may be inferior, such as when unburned electrode assemblies are discharged from the battery case and propagated to adjacent secondary battery cells in the event of thermal runaway.

[0056] According to one embodiment of the present invention, the jelly-roll type electrode assembly may include a plurality of separators. For example, the jelly-roll type electrode assembly may have a structure in which a first separator / negative electrode / second separator / positive electrode are stacked in sequence. The separator (200) separates the negative electrode (110) and the positive electrode (310) and provides a passage for the movement of lithium ions. It can be used without special limitations as long as it is typically used as a separator in a secondary battery, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a stacked structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a high-melting-point glass fiber or a polyethylene terephthalate fiber, may be used. Furthermore, the separator may typically have a thickness of 10 μm or more and 20 μm or less, and a separator may be used in which a slurry containing a ceramic component or a polymer material is coated on the substrate layer to secure heat resistance or mechanical strength using the aforementioned separator material as a substrate layer, and may optionally be used in a single-layer or multi-layer structure.

[0057] According to one embodiment of the present invention, the separator may include a coating layer provided on both sides. Specifically, the separator may include a coating layer provided on both sides of a substrate layer, and the friction coefficient may be controlled by controlling the composition, content, and particle size of the coating layer.

[0058] According to one embodiment of the present invention, the coating layer may comprise an inorganic component, a binder component, and a lithium salt. Since the separator comprises the aforementioned components, the cell stability may be excellent because, even though it includes a binder for improving adhesion to the electrode and an inorganic component for improving the mechanical strength of the separator, the leaching of the lithium salt contained in the coating layer does not result in an increase in internal resistance.

[0059] Specifically, the lithium salt may be substantially the same as that contained in the electrolyte of a lithium secondary battery, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 It may be one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, and lithium tetraphenylborate.

[0060] The above-mentioned inorganic component is within the operating voltage range of the battery (e.g., Li / Li). + As long as it does not cause oxidation and / or reduction reactions, i.e., electrochemical reactions, with the anode or cathode current collector at a standard of 0–5 V and does not impair conductivity, it is not particularly limited, for example, BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB (Mg3Nb 2 / 3 )O 3- It may be one or more selected from the group consisting of PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, and TiO2.

[0061] The above binder is not particularly limited as long as it is a component that is not easily dissolved by the electrolyte while exhibiting bonding strength with the electrode laminated on the separator and bonding strength between the inorganic component and the lithium salt in the mixed coating layer. For example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-cohexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polyvinylidene fluoride-chlorotrifluoroethylene (PVdF-CTFE), polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, It may be one or more mixtures selected from the group consisting of cyanoethylpolyvinyl alcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, and polyimide, and preferably may be PVdF or PVdF-CTFE.

[0062] According to one embodiment of the present invention, the positive electrode may comprise a positive electrode current collector and a positive electrode active material layer provided on the positive electrode current collector. Specifically, referring to FIG. 3, the positive electrode (310) may comprise a positive electrode current collector (301) and a positive electrode active material layer (302, 303) formed on one or both sides of the positive electrode current collector (301) and containing a positive electrode active material. In other words, the positive electrode active material layer (302, 303) may be formed on the positive electrode holding portion (310b) of the positive electrode current collector (301), and the side not provided with the positive electrode active material layer may be represented as a positive electrode non-retaining portion (310a).

[0063] According to one embodiment of the present invention, the positive current collector may include a positive retaining portion to which a positive active material is applied and a positive non-positive portion to which a positive active material is not applied, and may include a tab on the positive non-positive portion. Specifically, the positive (310) may include a positive non-positive portion (310a) and may include a positive tab formed on the positive non-positive portion (310a).

[0064] According to one embodiment of the present invention, the anode (310) may have an anode-free portion (310a) at one end in the winding axis direction (direction parallel to the Z-axis). At least a portion of the anode-free portion (310a) may be used as an electrode tab itself. That is, the anode-free portion (310a) may function as an anode tab provided in the anode (310). For example, the anode-free portion (310a) may be provided on the upper side in the width direction (direction parallel to the Z-axis) of the electrode assembly (1000) housed in the battery case (600). An insulating layer may be additionally provided at the boundary between the anode-free portion (310a) and the anode-holding portion (310b). The insulating layer may prevent short circuits of the electrodes even if the separator shrinks.

[0065] According to one embodiment of the present invention, the electrode assembly may comprise a positive electrode, a separator, and a negative electrode stacked and wound, wherein the positive electrode comprises a positive current collector; and a positive active material layer provided on at least one surface of the positive current collector and having a longitudinal end at the same position as the positive current collector. Specifically, referring to FIG. 3, the electrode assembly may comprise a positive electrode (310), a separator (200), and a negative electrode (110) stacked and wound, wherein the positive electrode (310) comprises a positive current collector (301); and a positive active material layer (302, 303) provided on at least one surface of the positive current collector (301) and having a longitudinal end (310e) at the same position as the positive current collector (301). In other words, the longitudinal end (310e) of the positive electrode may be in the form of a free-edge.

[0066] Through this, economic efficiency can be secured by reducing the area of ​​the unnecessary unused portion of the positive current collector, and the slitting process can be performed after forming an active material layer on the electrode, thereby allowing the roll-to-roll process including the slitting and winding processes to be carried out more efficiently. Here, 'same position' means that the longitudinal ends are identical, and may include cases where the ends are formed at substantially the same position due to process errors that may occur during the slitting process, etc.

[0067] According to one embodiment of the present invention, the positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery. Specifically, the positive current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. That is, the positive current collector may be provided in the form of surface-treated stainless steel, aluminum foil, etc.

[0068] In addition, the anode current collector can typically have a thickness of 3 to 50 μm, and fine irregularities can be formed on the surface of the current collector to increase the adhesion of the anode active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0069] According to one embodiment of the present invention, the positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; or a compound with the chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (0≤x≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-y M y Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤y≤0.3); chemical formula LiMn 2-z M z Examples include lithium manganese composite oxides represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, satisfying 0.01≤z≤0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); and LiMn2O4 in which part of the Li of the chemical formula is substituted with alkaline earth metal ions, but are not limited thereto. The anode may also be Li-metal.

[0070] According to one embodiment of the present invention, the positive active material layer may further include a positive conductive material and a positive binder. The positive conductive material is used to impart conductivity to the electrode and can be used without special limitations as long as it has electronic conductivity without causing chemical changes in the battery being constructed. Specifically, the positive conductive material may be graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxide such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used.

[0071] In addition, the anode binder serves to improve adhesion between anode active material particles and adhesion between the anode active material and the anode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used.

[0072] According to one embodiment of the present invention, the cathode may comprise a cathode current collector and a cathode active material layer provided on the cathode current collector. Specifically, referring to FIG. 3, the cathode (110) may comprise a cathode current collector (101) and a cathode active material layer (102, 103) formed on one or both sides of the cathode current collector (101) and containing a cathode active material. In other words, the cathode active material layer (102, 103) may be formed on the cathode retaining portion (110b) of the cathode current collector (101), and the side not provided with the cathode active material layer may be represented as a cathode non-retaining portion (110a).

[0073] According to one embodiment of the present invention, the negative current collector may include a negative retaining portion where a negative active material layer is formed and a negative non-negative portion where a negative active material layer is not formed, and may include a tab on the negative non-negative portion. Specifically, the negative current collector (101) may include a negative non-negative portion (110a) and may include a negative tab formed on the negative non-negative portion (110a). Accordingly, the electrode assembly manufactured may include one or more negative tabs.

[0074] According to one embodiment of the present invention, the cathode (110) may have a cathode-free portion (110a) at one end in the width direction (direction parallel to the Z-axis) where no cathode active material is applied. At least a portion of the cathode-free portion (110a) may be used as an electrode tab itself. That is, the cathode-free portion (110a) may function as a cathode tab provided in the cathode (110). For example, the cathode-free portion (110a) may be provided at the lower part in the width direction (direction parallel to the Z-axis) of an electrode assembly (1000) housed in a battery case (600).

[0075] According to one embodiment of the present invention, the positive electrode unsupported portion (310a) and the negative electrode unsupported portion (110a) may be in a shape that protrudes in opposite directions. For example, referring to FIGS. 1 and FIGS. 5 to 8, the positive electrode unsupported portion (310a) may protrude toward the upper side in the width direction (direction parallel to the Z-axis) of the electrode assembly (1000), and the negative electrode unsupported portion (110a) may protrude toward the lower side in the width direction (direction parallel to the Z-axis) of the electrode assembly (1000). Accordingly, the positive electrode unsupported portion (310a) provided on the positive electrode (310) and the negative electrode unsupported portion (110a) provided on the negative electrode (110) may be in a shape that extends and protrudes in opposite directions along the width direction of the electrode assembly (1000), that is, the height direction (direction parallel to the Z-axis) of the secondary battery (2000).

[0076] According to one embodiment of the present invention, the negative electrode active material layer may comprise a negative electrode active material comprising one or more selected from the group consisting of silicon-based materials and carbon-based materials. Additionally, the negative electrode active material layer may further comprise a negative electrode conductive material and a negative electrode binder, and the negative electrode active material; the negative electrode conductive material; and the negative electrode binder may be any material used in the art without limitation.

[0077] According to one embodiment of the present invention, the negative current collector may be conductive without causing chemical changes in the battery, and is not particularly limited. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used as the negative current collector. Specifically, transition metals that adsorb carbon well, such as copper and nickel, may be used as the negative current collector. The thickness of the negative current collector may be 6 μm or more and 80 μm or less, but the thickness of the negative current collector is not limited thereto.

[0078] According to one embodiment of the present invention, the cathode binder may comprise at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and materials in which hydrogens thereof are substituted with Li, Na, or Ca, etc., and may also comprise various copolymers thereof.

[0079] According to one embodiment of the present invention, the cathode conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0081] Another embodiment of the present invention provides a secondary battery comprising: the electrode assembly; a positive terminal having a riveting structure; and a sealing body, wherein the electrode assembly is housed inside a battery case, the negative electrode and the battery case are electrically connected, the positive electrode and the positive terminal are electrically connected, and the sealing body seals an opening of the battery case so as to be insulated from the battery case.

[0082] A secondary battery according to one embodiment of the present invention can improve battery stability and lifespan characteristics by preventing an internal short circuit between the positive and negative electrodes through the separator overlapping portion even when the electrode assembly is deformed due to shrinkage / expansion of the electrodes during battery charging / discharging, and can prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to an internal short circuit, etc.

[0083] FIG. 4 illustrates a secondary battery according to one embodiment of the present invention, FIG. 5 is a cross-sectional view of the secondary battery of FIG. 4, and FIG. 6 to 8 are cross-sectional views showing a schematic configuration of a secondary battery according to one embodiment of the present invention.

[0084] According to one embodiment of the present invention, the positive terminal may have a riveting structure. Specifically, referring to FIGS. 4 to 6, the riveting structure may include a battery case (600) with one side open; a positive terminal (330) riveted through a through hole (H5) formed in the bottom portion (610) of the battery case; and a terminal gasket (340) provided between the positive terminal (330) and the outer diameter of the through hole (H5).

[0085] According to one embodiment of the present invention, the battery case (600) may be a cylindrical receptacle with one side open, and may be made of a conductive material such as metal. The material of the battery case (6000) may be, for example, aluminum. The opening of the battery case (600) with one side open may be defined as an open end. The side (outer surface) and the top surface of the battery case (600) may be formed integrally. The other side of the battery case (600) may be a flat surface (a surface parallel to the XY plane), i.e., a bottom part (610). The bottom part located opposite the open end may be defined as a closed end. The battery case (600) may accommodate an electrode assembly (1000) through the opening formed on one side and may also accommodate an electrolyte.

[0086] According to one embodiment of the present invention, the battery case (600) may be electrically connected to the electrode assembly (1000). For example, the battery case (600) may be electrically connected to the negative electrode (110) of the electrode assembly (1000). In this case, the battery case (600) may have the same polarity as the negative electrode (110).

[0087] According to one embodiment of the present invention, the battery case (600) may include a beading portion (620) pressed into the inside of the battery case (600) in an area adjacent to an open end; and a clamping portion (630) that extends and bends into the inside of the battery case (600) and wraps around and fixes the edge of the cap plate (641) together with a sealing gasket (140).

[0088] Specifically, referring to FIGS. 7 and 8, the beading portion (620) may be formed by pressing the outer circumference of the battery case (600), and may function as a support portion on which a seal (640) is seated, so that an electrode assembly (1000) having a size corresponding to the width of the battery case (600) does not come out through an opening formed at one end of the battery case (20).

[0089] The above-mentioned clamping portion (630) may be formed adjacent to the above-mentioned beading portion (620). Specifically, the above-mentioned clamping portion (630) may have a shape that is extended and bent to wrap around the outer surface of the sealing body (640) positioned adjacent to the above-mentioned beading portion (620) and a part of the cathode current collector plate (120) described later.

[0090] According to one embodiment of the present invention, the seal (640) may include a non-polar cap plate (641) and a sealing gasket (140) interposed between the edge of the cap plate (641) and the open end of the battery case (600). Specifically, the seal (640) may be seated on a beading portion (620) formed in the battery case (600). Additionally, the seal (640) may be secured by a clamping portion (630). A sealing gasket (140) may be interposed between the seal (640) and the clamping portion (630) of the battery case (600) to ensure airtightness of the battery case (600).

[0091] According to one embodiment of the present invention, the seal (640) may be made of a metal material to ensure rigidity. Additionally, the seal (640) may cover the open end of the battery case (600). In other words, the seal (640) may form one side of the secondary battery (2000), that is, the other side of the bottom portion (610).

[0092] According to one embodiment of the present invention, the seal (640) may seal the open end of the battery case (600) so as to be insulated from the battery case (600). Specifically, the seal (640) may not have polarity, even if it is made of a conductive metal material. In other words, the seal (640) may be electrically insulated from the battery case (600) and the positive terminal (330) which function as the negative terminal (130).

[0093] Therefore, the seal (640) may not function as a positive terminal (330) or a negative terminal (130). Accordingly, the seal (640) does not need to be electrically connected to the electrode assembly (1000) and the battery case (600), and its material does not necessarily have to be a conductive metal.

[0094] According to one embodiment of the present invention, the cap plate (641) may include a venting portion (641a) that ruptures when the internal pressure of the battery case (600) exceeds a critical value.

[0095] According to one embodiment of the present invention, the positive terminal (330) may be electrically connected to the positive electrode (310). That is, the positive terminal (330) may be electrically connected to the positive electrode (310) and may have opposite polarity to the battery case (600) which is electrically connected to the negative electrode (110). For example, the surface of the positive terminal (330) may be exposed to the outside.

[0096] According to one embodiment of the present invention, the positive terminal (330) may be made of a conductive metal material. The positive terminal (330) may, for example, penetrate the center of the closed end, i.e., the bottom portion (610), formed at one end of the battery case (600). A portion of the positive terminal (330) may be exposed to the outside of the battery case (600), and the remaining portion may be located inside the battery case (600). The positive terminal (330) may be fixed on the inner surface of the closed end of the battery case (600), for example, by riveting. The positive terminal (330) may penetrate the insulator (500) and be coupled to the positive non-positive portion (310a) provided on the positive current collector plate (320) or the positive (310). In this case, the positive terminal (330) may have a positive electrode and may be electrically insulated from the battery case (600) which functions as the negative terminal (130).

[0097] Electrical insulation between the positive terminal (330) and the battery case (600) can be achieved in various ways. For example, insulation can be achieved by interposing a terminal gasket (340) between the positive terminal (330) and the battery case (600). Alternatively, insulation can be achieved by forming an insulating coating layer on a part of the positive terminal (330). Or, a method of structurally and firmly fixing the positive terminal (330) so that contact between the positive terminal (330) and the battery case (600) is impossible may be applied, or multiple of the aforementioned methods may be applied together.

[0098] According to one embodiment of the present invention, the positive terminal (330) may comprise: a body portion (331) inserted into the through hole (H5); an outer flange portion (332) extending along the outer surface (610a) from one side of the body portion (331) exposed through the outer surface (610a) of the bottom portion (610); and an inner flange portion (333) extending toward the inner surface (610b) from the other side of the body portion (331) exposed through the inner surface (610b) of the bottom portion (610).

[0099] According to one embodiment of the present invention, the positive terminal (330) may further include a flat portion (331a) provided at the end of the body portion (331) exposed through the inner surface (610b) of the bottom portion (610). Specifically, the flat portion (331a) and the inner surface (610b) of the bottom portion (640) of the battery case (600) may be parallel to each other. Here, 'parallel' means substantially parallel when observed with the naked eye.

[0100] According to one embodiment of the present invention, the angle (θ) between the inner flange portion (333) and the inner surface (610b) of the bottom portion (610) of the battery case (600) may be 0° or greater and 60° or less. The size of the angle may be determined by the corking strength when the positive terminal (330) is installed in the through hole (H5) of the battery case (600) by the corking method, for example, as the corking strength increases, the angle (θ) may decrease to 0°, and if the angle exceeds 60°, the sealing effect of the terminal gasket (340) may be reduced.

[0101] According to one embodiment of the present invention, a recess may be provided between the inner flange portion (333) and the flat portion (331a). The recess may be formed by the shape of a corking jig when the positive terminal (330) is installed in the through hole (H5) of the battery case (600) by a corking method.

[0102] According to one embodiment of the present invention, the recess may have a cross-sectional structure of an asymmetric groove. For example, the asymmetric groove may be V-shaped. The asymmetric groove may include a side wall of a flat portion (331a) and an inclined surface of an inner flange portion (333) connected to the end of the side wall, and the side wall may be substantially perpendicular to the inner surface (610b) of the bottom portion (610) of the battery case (600). Here, 'vertical' means that it is substantially perpendicular when observed visually.

[0103] According to one embodiment of the present invention, the terminal gasket (340) may be interposed between the battery case (600) and the positive terminal (330) to prevent the battery case (600) and the positive terminal (330), which have opposite polarities, from coming into contact with each other. That is, the terminal gasket (340) may block the electrical connection between the battery case (600) and the positive terminal (330). Through this, the closed end of the battery case (600) having a flat shape, i.e., the bottom part (610), may function as the negative terminal (130) of the secondary battery (2000).

[0104] According to one embodiment of the present invention, the terminal gasket (330) comprises an outer gasket portion (342) interposed between the outer flange portion (332) and the outer surface (610a) of the bottom portion (610); and an inner gasket portion (341) interposed between the inner flange portion (333) and the inner surface (610b) of the bottom portion (610), wherein the inner gasket portion (341) may be extended longer than the inner flange portion (333). Specifically, the inner gasket portion (341) may be extended longer than the inner flange portion (333) while forming an angle of 0° to 60° with the inner surface (610b) of the bottom portion (610) of the battery case (600).

[0105] According to one embodiment of the present invention, the thickness of the inner gasket portion (341) and the outer gasket portion (342) may vary depending on the location. For example, the thickness of the area of ​​the inner gasket portion (341) interposed between the inner side of the through hole (H5) connected to the inner surface (610b) of the bottom portion (610) of the battery case (600) and the inner flange portion (333) may be relatively small. Specifically, a minimum thickness point may exist in the terminal gasket (340) area interposed between the inner side of the through hole (H5) and the inner flange portion (333).

[0106] According to one embodiment of the present invention, the inner side of the through hole (H5) may include an opposing surface facing the inner flange portion (333). Meanwhile, the upper and lower ends of the inner wall of the through hole (H5), which is perpendicular to the bottom portion (610) of the battery case (600), may be corner-cut to form a tapered surface toward the positive terminal (330), and the upper and / or lower ends of the inner wall of the through hole (H5) may be deformed into a smooth curved surface with curvature. In this case, the stress applied to the terminal gasket (340) near the upper and / or lower ends of the inner wall of the through hole (H5) can be further relieved.

[0107] According to one embodiment of the present invention, the secondary battery may further include a negative electrode collector plate. Specifically, the negative electrode collector plate (120) may be coupled to the other end in the width direction of the electrode assembly (1000). The negative electrode collector plate (120) may be made of a conductive metal material. The negative electrode collector plate (120) may be connected to a negative electrode non-transferable portion (110a) provided on the negative electrode (110). Additionally, the negative electrode collector plate (120) may be electrically connected to a battery case (600). The negative electrode collector plate (120) may be fixed by being interposed between the inner surface of the battery case (600) and a sealing gasket (140). Meanwhile, the negative electrode collector plate (120) may be welded to the inner wall surface of the battery case (600).

[0108] According to one embodiment of the present invention, the cathode collector plate (120) may have a plurality of irregularities formed radially on one surface. When the irregularities are formed, the cathode collector plate (120) may be pressed to press the irregularities into the cathode non-removable portion (110a).

[0109] The above-mentioned cathode collector plate (120) may be coupled to one end in the width direction of the cathode non-coupling portion (110a). The coupling between the cathode non-coupling portion (110a) and the cathode collector plate (120) may be achieved, for example, by laser welding. The laser welding may be performed by partially melting the base material of the cathode collector plate (120), or by interposing solder for welding between the cathode collector plate (120) and the cathode non-coupling portion (110a). In this case, it is preferable that the solder has a lower melting point compared to the cathode collector plate (120) and the cathode non-coupling portion (110a). Meanwhile, in addition to laser welding, resistance welding, ultrasonic welding, etc. are possible, but the welding method is not limited thereto.

[0110] According to one embodiment of the present invention, the cathode collector plate (120) may be coupled to a coupling surface formed by bending one end of the cathode non-coupling portion (110a) in the width direction parallel to the cathode collector plate (120). The bending direction of the cathode non-coupling portion (110a) may be, for example, a direction toward the core portion (C) of the electrode assembly (1000). When the cathode non-coupling portion (110a) has a bent shape, the space occupied by the cathode non-coupling portion (110a) is reduced, which can lead to an improvement in energy density. Additionally, due to the increase in the coupling area between the cathode non-coupling portion (110a) and the cathode collector plate (120), an improvement in coupling strength and a reduction in resistance may be achieved.

[0111] FIG. 9 illustrates an exemplary form of a negative electrode collector plate according to one embodiment of the present invention.

[0112] Referring to FIG. 9, the negative electrode collector plate (120) may include a central part (121) welded to the uncoated part (110a) of the negative electrode (110); a tab connecting part (122) extending from the central part (121) and coupled to a negative electrode tab provided in the electrode assembly (1000); and a battery case connecting part (123) extending from the central part (121) and located between adjacent tab connecting parts (122).

[0113] According to one embodiment of the present invention, the battery case coupling portion (123) may be interposed between the beading portion (620) and the sealing gasket (140) and fixed by the clamping portion (630).

[0114] According to one embodiment of the present invention, the battery case coupling portion (123) of the negative electrode current collector plate (120) may include a contact portion (123a) fixed by welding to the inner circumference of the beading portion (620) adjacent to the clamping portion (630); and at least one bending portion having a changing direction of extension, and a connecting portion (123b) connecting the central portion (121) and the contact portion (123a).

[0115] According to one embodiment of the present invention, the negative electrode collector plate (120) includes a negative electrode collector plate hole (H2) formed at a position corresponding to the core hollow (H1) of the electrode assembly (1000), and the difference between the diameter of the negative electrode collector plate hole (H2) and the diameter of the core hollow (H1) of the electrode assembly may be 0.1 mm or more and 1 mm or less. Specifically, the difference in diameter between the diameter of the negative electrode collector plate hole (H2) and the diameter of the core hollow (H1) of the electrode assembly may be 0.1 mm or more, 0.2 mm or more, 0.3 or more, 0.4 or more, or 0.5 or more, and may be 1 mm or less, 0.9 mm or less, 0.8 mm or less, 0.7 mm or less, or 0.6 mm or less. More specifically, it may be preferable for the diameter of the core hollow (H1) to be larger than the diameter of the negative electrode collector plate hole (H2), for example, the diameter of the core hollow (H1) may be formed to be 5 mm or more and 7.5 mm or less, and the diameter of the negative electrode collector plate hole (H2) may be formed to be 0.5 mm or more and 1 mm or less smaller than this.

[0116] When the aforementioned difference in diameter is satisfied, processability can be ensured while preventing the ejection of the electrode assembly during thermal runaway. Specifically, reducing the diameter of the core hollow (H1) may be advantageous for preventing the ejection of the electrode assembly during thermal runaway of the secondary battery. However, as mentioned above, in the case of a secondary battery with an increased form factor, it may be necessary to secure the rigidity of the winding core to support the increased weight of the electrode assembly, and if the winding core diameter is increased to secure the rigidity of the winding core, the diameter of the core hollow (H1) may also increase. Meanwhile, if the diameter of the cathode collector plate hole (H2) is excessively small, it may be impossible to inject the electrolyte through the cathode collector plate hole (H2) or to weld using a laser welder (CRW), which may reduce processability. If the diameter of the cathode collector plate hole (H2) is excessively large, it may be disadvantageous to prevent the ejection of the electrode assembly during thermal runaway, and the reduction in the bonding area between the cathode non-bonding portion (110a) and the cathode collector plate (120) may result in a decrease in bonding strength and an increase in resistance. Meanwhile, if the difference between the diameter of the cathode collector plate hole (H2) and the diameter of the core hollow (H1) of the electrode assembly exceeds a certain range, alignment between the electrode assembly and the cathode collector plate is not easy, which may reduce processability.

[0117] According to one embodiment of the present invention, the secondary battery may further include a positive current collector. Specifically, the positive current collector (320) may be welded to the non-bonded portion (310a) of the positive (310), and at least a portion of the positive current collector (320) may be welded to the flat portion (331a) of the positive terminal (330).

[0118] According to one embodiment of the present invention, the positive current collector plate (320) may be coupled to one end in the width direction of the electrode assembly (1000). Specifically, the positive current collector plate (320) may be coupled to the positive non-positive portion (310a) provided on the positive (310) at one end in the width direction of the electrode assembly (1000). The positive current collector plate (320) may be made of a conductive metal material.

[0119] According to one embodiment of the present invention, the positive electrode collector plate (320) may have a plurality of irregularities formed radially on one surface. When the irregularities are formed, the positive electrode collector plate (320) may be pressed to press the irregularities into the uneven portion (310a) provided on the positive electrode (310).

[0120] According to one embodiment of the present invention, the connection between the anode non-positive portion (310a) and the anode collector plate (320) may be achieved, for example, by laser welding. The laser welding may be performed by partially melting the base material of the anode collector plate (320), or by interposing solder for welding between the anode collector plate (320) and the anode non-positive portion (310a). In this case, it is preferable that the solder has a lower melting point compared to the anode collector plate (320) and the anode non-positive portion (310a). Meanwhile, in addition to laser welding, resistance welding, ultrasonic welding, etc., are possible, but the welding method is not limited thereto.

[0121] According to one embodiment of the present invention, the secondary battery may further include an insulator. Specifically, the insulator (500) may prevent contact between the positive electrode unoccupied portion (310a) and the battery case (600) and / or contact between the positive electrode current collector plate (320) and the battery case (600). That is, the insulator (500) may be housed inside the battery case (600) and configured to block electrical connection between the positive electrode unoccupied portion (310a) and the battery case (600). Accordingly, the insulator (500) may be made of a material having insulating properties, and may include, for example, a polymer material.

[0122] According to one embodiment of the present invention, the insulator (500) may be interposed between the positive current collector (320) and the inner surface (610b) of the bottom portion (610) of the battery case (600); and between the inner surface of the battery case (600) and the electrode assembly (1000). Specifically, the insulator (500) may be provided between one end in the width direction of the electrode assembly (1000) and the inner surface (610b) of the bottom portion (610) of the battery case (600), or between the positive current collector (320) coupled to one end in the width direction of the electrode assembly (1000) and the inner surface of the battery case (600).

[0123] According to one embodiment of the present invention, the insulator (500) may include a welding hole (H4) that exposes the flat portion (331a) of the positive terminal (330) toward the positive current collector plate (320), and may cover the surface of the positive current collector plate (320) and one edge of the electrode assembly (1000).

[0124] According to one embodiment of the present invention, the secondary battery may be a cylindrical secondary battery. In other words, the battery case in which the jelly-roll type electrode assembly is accommodated may be cylindrical. The dimensions of the battery case may be such that the circular diameter at both ends in the width direction is 30 mm to 55 mm and the height is 60 mm to 120 mm. For example, the circular diameter x height of the cylindrical battery case may be 40 mm x 60 mm, 40 mm x 80 mm, or 40 mm x 90 mm, or 40 mm x 120 mm. The secondary battery may be a secondary battery cell.

[0125] Preferably, the cylindrical secondary battery cell may be a cylindrical secondary battery cell having, for example, a ratio of form factor (defined as the ratio of the diameter of the cylindrical secondary battery cell to the height, i.e., the ratio of the diameter (Φ) to the height (H)) greater than about 0.4.

[0126] Here, the form factor may refer to a value representing the diameter and height of a cylindrical battery cell. A cylindrical secondary battery cell according to one embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, a 46800 cell, or a 46900 cell. In the numerical value representing the form factor, the first two digits may represent the diameter of the cell, the next two digits may represent the height of the cell, and the last digit 0 may indicate that the cross-section of the cell is circular.

[0127] A secondary battery cell according to one embodiment of the present invention may be a cylindrical secondary battery cell having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0128] A secondary battery cell according to another embodiment may be a cylindrical secondary battery cell having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0129] A secondary battery cell according to another embodiment may be a cylindrical secondary battery cell having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0130] A secondary battery cell according to another embodiment may be a cylindrical secondary battery cell having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0131] A secondary battery cell according to another embodiment may be a cylindrical secondary battery cell having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0132] A battery cell according to another embodiment may be a cylindrical secondary battery cell having a diameter of about 46 mm, a height of about 90 mm, and a form factor ratio of 0.511.

[0133] Conventionally, battery cells with a form factor ratio of about 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 about 18 mm, its height is about 65 mm, and its form factor ratio is 0.277. Also, in the case of the 21700 cell, its diameter is about 21 mm, its height is about 70 mm, and its form factor ratio is 0.300.

[0135] One embodiment of the present invention provides a battery pack comprising at least one secondary battery according to the above embodiment and an automobile comprising at least one battery pack.

[0136] A battery pack and an automobile according to one embodiment of the present invention suppress heat generation and ignition caused by an internal short circuit of a secondary battery cell, and prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs in each secondary battery cell, thereby improving stability.

[0137] The secondary battery according to the above-described embodiment may be used to manufacture the battery pack.

[0138] FIG. 10 illustrates a battery pack according to one embodiment of the present invention. Specifically, FIG. 10 is a diagram showing the schematic configuration of a battery pack including the secondary battery of FIG. 4.

[0139] Referring to FIG. 10, a battery pack (3000) according to one embodiment of the present invention may include an assembly in which a secondary battery (1000) is electrically connected and a pack housing (700) that accommodates the same. The secondary battery (1000) may be a secondary battery cell according to the above embodiment.

[0140] According to one embodiment of the present invention, the battery pack may further include components such as a busbar for electrical connection of cylindrical secondary batteries (1000), a cooling unit, and an external terminal.

[0141] According to one embodiment of the present invention, the battery pack (3000) may be mounted on a vehicle (4000). Specifically, the vehicle may be an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may include a four-wheeled vehicle or a two-wheeled vehicle.

[0142] FIG. 11 illustrates a vehicle according to one embodiment of the present invention. Specifically, FIG. 11 is a diagram showing the schematic configuration of a vehicle including the battery pack of FIG. 10.

[0143] Referring to FIG. 11, a vehicle (4000) according to one embodiment of the present invention may include a battery pack (3000) according to one embodiment of the present invention. The vehicle (4000) may operate by receiving power from the battery pack (3000) according to one embodiment of the present invention.

[0145] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0147] Examples

[0148] Example 1

[0149] Electrode assembly manufacturing

[0150] A cathode (cathode current collector: Cu foil, cathode active material: graphite), a separator made of polyethylene material with an SRS coating layer, and an anode (anode current collector: Al foil, active material: NCM) were prepared.

[0151] Before winding the jelly-roll type electrode assembly, two separator sheets were overlapped, and a separator extension was provided in the reverse direction of the winding direction for a length corresponding to two turns of the core.

[0152] Afterwards, winding was started by folding back a point corresponding to 2 turns of the core from the longitudinal end of the first and second separators in the winding direction, and the cathode and anode were fed in sequence to manufacture a jelly-roll type electrode assembly.

[0153] Specifically, the core portion of the jelly-roll type electrode assembly has a structure according to FIG. 3 (a) by interposing a separator extension portion with a length corresponding to one turn from the longitudinal end of the anode between a separator located on one side in the winding axis direction of the anode and a separator located on one side of the cathode.

[0154] At this time, the diameter of the hollow core of the electrode assembly was adjusted to 6 mm, the diameter of one end perpendicular to the winding axis of the electrode assembly to 45 mm, and the longitudinal length of the separator overlap portion to 20 mm.

[0155] manufacturing of secondary batteries

[0156] After inserting the manufactured electrode assembly into a cylindrical battery case (diameter: 45 mm to 47 mm, material: steel) having an opening on one side, an electrolyte solution was injected by mixing ethylene carbonate (EC):ether methyl carbonate (EMC) in a volume ratio of 30:70 and dissolving LiPF6 to 1.0 M, and the cylindrical battery case was sealed with a sealant to manufacture a secondary battery.

[0157] At this time, by manufacturing a riveting structure for a positive terminal such that a positive terminal is riveted through a through hole formed in the bottom portion of the battery case and a terminal gasket is provided between the positive terminal and the outer diameter of the through hole, in a secondary battery including the same, the negative electrode of the electrode assembly and the battery case are electrically connected, the positive electrode and the positive terminal are electrically connected, and the sealant is insulated from the battery case.

[0158] Example 2

[0159] A jelly-roll type electrode assembly and a secondary battery were manufactured in the same manner as in Example 1, except that a separator overlapping portion was provided by interposing a separator extension portion with a length corresponding to 1.6 turns from the longitudinal end of the anode between a separator located on one side in the winding axis direction of the anode and one side of the cathode in the core portion of the jelly-roll type electrode assembly. At this time, the longitudinal length of the separator overlapping portion was adjusted to approximately 40 mm.

[0160] Example 3

[0161] A jelly-roll type electrode assembly and a secondary battery were manufactured in the same manner as in Example 1, except that a separator overlapping portion was provided by interposing a separator extension portion with a length corresponding to 2.0 turns from the longitudinal end of the anode between a separator located on one side in the winding axis direction of the anode and one side of the cathode in the core portion of the jelly-roll type electrode assembly. At this time, the longitudinal length of the separator overlapping portion was adjusted to about 50 mm.

[0162] Reference Example 1

[0163] A jelly-roll type electrode assembly and a secondary battery were manufactured in the same manner as in Example 1, except that a separator overlapping portion was provided by interposing a separator extension portion with a length corresponding to 0.4 turns from the longitudinal end of the anode between a separator located on one side in the winding axis direction of the anode and one side of the cathode in the core portion of the jelly-roll type electrode assembly. At this time, the longitudinal length of the separator overlapping portion was adjusted to about 10 mm.

[0164] Reference Example 2

[0165] A jelly-roll type electrode assembly and a secondary battery were manufactured in the same manner as in Example 1, except that a separator overlapping portion was provided by interposing a separator extension portion with a length corresponding to 0.6 turns from the longitudinal end of the anode between a separator located on one side in the winding axis direction of the anode and one side of the cathode in the core portion of the jelly-roll type electrode assembly. At this time, the longitudinal length of the separator overlapping portion was adjusted to about 15 mm.

[0166] Comparative Example 1

[0167] A jelly-roll type electrode assembly and a secondary battery were manufactured in the same manner as in Example 1, except that the diameter of the hollow core of the electrode assembly was adjusted to 8 mm.

[0169] Experimental Example

[0170] Experimental Example 1 - Appearance Evaluation

[0171] The secondary batteries prepared in Example 1 and Comparative Example 1 above were each prepared, the electrode assembly was placed inside a battery case, and immediately after the opening of the battery case was vented with a sealant, the occurrence of the phenomenon of the core electrode assembly rising was evaluated using external images and computed tomography (CT) images, and the results are shown in Table 1 below. Specifically, '○' was indicated when the core rise was 7 mm or more and the core was visible to the naked eye on the exterior of the secondary battery cell, and 'Ⅹ' was indicated when the core rise was not visible to the naked eye.

[0172] Referring to Table 1 below, it was confirmed that the secondary battery according to Comparative Example 1 had a core portion rise of about 10 to 20 mm, whereas the secondary battery according to one embodiment of the present invention did not have a phenomenon in which the core portion electrode assembly rose.

[0173] Through this, it can be seen that the jelly-roll type electrode assembly and secondary battery according to one embodiment of the present invention can improve battery stability and lifespan characteristics by preventing internal short circuits between the positive and negative electrodes by the separator overlapping portion even when the electrode assembly is deformed due to shrinkage / expansion of the electrodes during battery charging / discharging, and can prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to internal short circuits, etc.

[0174] Experimental Example 2 - Secondary Battery Safety Evaluation

[0175] Secondary batteries prepared in Examples 1 to 3, Reference Example 1, Reference Example 2, and Comparative Example 1 were prepared, and the safety of the secondary batteries was evaluated by measuring the burn duration time under thermal runaway conditions, and the results are shown in Table 1 below. At this time, the burn duration time was measured as the time from the occurrence of a premature lid pop due to internal pressure when at least a part of the seal sealing the opening of the battery case is removed until the discharge or finishing of the electrode assembly. Since there is a high possibility that an unburned electrode assembly will be discharged if the burn duration time is less than 1000 ms, it was checked whether the burn duration time was 1000 ms or more.

[0177]

[0178]

[0180] Referring to Table 1 above, it was confirmed that the secondary batteries according to Examples 1 to 3, in which the core hollow diameter is 6 mm, have a burn duration time of 1000 ms or more, and that the electrode assembly does not discharge when thermal runaway occurs, and have a sufficient burn duration time.

[0181] On the other hand, it was confirmed that in the secondary battery according to Comparative Example 1, in which the core hollow diameter is 8 mm, the flame sustainment time is less than 1000 ms. Specifically, it was confirmed that in the secondary battery cells of Comparative Examples 1-5 and 1-6, in which the flame sustainment times are 82 ms and 97 ms, respectively, the discharge of an unburned electrode assembly occurs when thermal runaway occurs. In addition, it was confirmed that the secondary battery cell of Comparative Example 1-8 has a short flame sustainment time of 250 ms, so it does not have a sufficient flame sustainment time for the electrode assembly in which thermal runaway occurred to burn.

[0182] Through this, it can be seen that a secondary battery according to one embodiment of the present invention can prevent the problem of an unburned electrode assembly being discharged from the battery case and propagating to an adjacent secondary battery cell when thermal runaway occurs due to an internal short circuit, even in a secondary battery having an increased form factor, by adjusting the diameter of the core portion of the electrode assembly to a specific range.

[0183] Meanwhile, it was confirmed that when the longitudinal length of the separator overlap portion of the secondary battery according to Reference Example 1 and Reference Example 2, in which the core portion hollow diameter is 6 mm, is adjusted to 0.4 turns and 0.6 turns, respectively, there are cases where the electrode assembly in which thermal runaway occurs does not have a sufficient flame sustainment time to burn, such as in the secondary battery cells of Reference Example 1-5 and Reference Example 2-2, in which the flame sustainment time is 310 ms and 501 ms, respectively.

[0184] Through this, it can be seen that the secondary battery according to one embodiment of the present invention has a superior effect in preventing the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells, even when thermal runaway occurs due to an internal short circuit, by adjusting the longitudinal length of the separator overlap portion to a specific range, by means of frictional force caused by the separator overlap portion.

[0185] In other words, it can be seen that the jelly-roll type electrode assembly and secondary battery according to one embodiment of the present invention can improve battery stability and lifespan characteristics by preventing an internal short circuit between the positive and negative electrodes through the separator overlapping portion even when the electrode assembly is deformed due to shrinkage / expansion of the electrodes during battery charging / discharging, and can prevent the problem of unburned electrode assembly being discharged from the battery case and propagating to adjacent secondary battery cells even when thermal runaway occurs due to an internal short circuit, etc.

[0187] The above detailed description is intended to illustrate and explain the present invention. Furthermore, the foregoing merely illustrates and describes preferred embodiments of the present invention, and as described above, the present invention may be used in various other combinations, modifications, and environments, and may be modified or altered within the scope of the concept of the invention disclosed herein, the scope equivalent to the foregoing disclosure, and / or the scope of the art or knowledge. Accordingly, the above detailed description of the invention is not intended to limit the present invention to the disclosed embodiments. Additionally, the appended claims should be interpreted as including other embodiments. Explanation of the symbols

[0189] 1000: Electrode assembly C: Core section H1: Core section hollow Φ1: Diameter of the hollow core Φ2: Cross-sectional diameter of the electrode assembly perpendicular to the winding axis 110: Cathode 101: Cathode current collector 102, 103: Cathode active material layer 110a: Cathode non-cathode region 110b: Cathode retaining part 120: Cathode current collector 121: Center 122: Tab joint 123: Battery case connection part 123a: Contact part 123b: Connection H2: Cathode collector plate hole 130: Negative terminal 140: Sealing gasket 200, 200': Separator S: Separator overlap section 310: Anode 301: Positive current collector 302, 303: Anode active material layer 310a: Positive indeterminate portion 310b: Anode retainer 310e: Longitudinal end of the anode 320: Positive current collector 321: Center 330: Positive terminal 331: Body 331A: Flat section 332: External flange 333: Internal flange 340: Terminal gasket 341: Internal gasket part 342: External gasket part 400: Step section H3: Empty space in the stepped section L1: Distance between the longitudinal end of the stepped portion and the longitudinal end of the positive electrode T: Thickness of the anode L2: Distance between the longitudinal end of the separator overlap and the longitudinal end of the anode 500: Insulator H4: Welding hole 600: Battery case 610: Bottom part 620: Bidding Department 630: Climbing section 640: Seal 641: Cap plate 641a: Venting section H5: Through hole 700: Pack Housing 2000: Secondary battery 3000: Battery pack 4000: Car

Claims

Claim 1 A jelly-roll type electrode assembly in which a cathode, a separator, and an anode are sequentially stacked and wound, wherein the anode comprises a first surface in the direction of the winding axis of the jelly-roll type electrode assembly and a second surface opposite to the first surface, and in the core portion of the electrode assembly, a separator overlap portion is included between the anode and the cathode facing the first surface of the anode; or between the anode and the cathode facing the second surface of the anode, and the core portion of the electrode assembly comprises a hollow having a diameter of 5 mm or more and 7.5 mm or less, and the longitudinal length of the separator overlap portion is 100% or more and 300% or less based on 100% of the inner circumference of the electrode assembly. Claim 2 In claim 1, the above-mentioned separator overlap portion is a jelly-roll type electrode assembly in which the separator arranged in overlap is three layers. Claim 3 delete Claim 4 A jelly-roll type electrode assembly according to claim 1, wherein the separator comprises a coating layer provided on both sides, and the coating layer comprises an inorganic component, a binder component, and a lithium salt. Claim 5 A jelly-roll type electrode assembly according to claim 1, wherein the positive electrode comprises a positive current collector; and a positive active material layer provided on at least one surface of the positive current collector and having a longitudinal end at the same position as the positive current collector. Claim 6 A secondary battery comprising: an electrode assembly according to any one of claims 1, 2, 4 and 5; a positive terminal having a riveting structure; and a sealing body, wherein the electrode assembly is housed inside a battery case, the negative electrode and the battery case are electrically connected, the positive electrode and the positive terminal are electrically connected, and the sealing body seals an opening of the battery case so as to be insulated from the battery case. Claim 7 In claim 6, the riveting structure comprises: a battery case with one side open; a positive terminal riveted through a through hole formed in the bottom portion of the battery case; and a terminal gasket provided between the positive terminal and the outer diameter of the through hole, in a secondary battery. Claim 8 A secondary battery according to claim 7, wherein the positive terminal comprises: a body portion inserted into the through hole; an outer flange portion extending along the outer surface from one side of the body portion exposed through the outer surface of the bottom portion; and an inner flange portion extending toward the inner surface from the other side of the body portion exposed through the inner surface of the bottom portion. Claim 9 A secondary battery according to claim 8, wherein the positive terminal further comprises a flat portion provided at the end of the body portion exposed through the inner surface of the bottom portion. Claim 10 A secondary battery according to claim 9, wherein a recess portion is provided between the inner flange portion and the flat portion. Claim 11 In item 10, the above-mentioned recess portion has an asymmetric groove cross-sectional structure, in a secondary battery. Claim 12 A secondary battery according to claim 8, wherein the terminal gasket comprises an outer gasket portion interposed between the outer flange portion and the outer surface of the bottom portion; and an inner gasket portion interposed between the inner flange portion and the inner surface of the bottom portion, wherein the inner gasket portion is extended longer than the inner flange portion. Claim 13 A secondary battery according to claim 6, wherein the sealing body comprises a non-polar cap plate and a sealing gasket interposed between the edge of the cap plate and the open end of the battery case, and the battery case comprises a beading portion pressed into the inside of the battery case in an area adjacent to the open end; and a clamping portion extending and bent into the inside of the battery case to wrap around and secure the edge of the cap plate together with the sealing gasket. Claim 14 A secondary battery according to claim 13, wherein the cap plate includes a venting portion that ruptures when the internal pressure of the battery case exceeds a critical value. Claim 15 A secondary battery according to claim 13, further comprising a negative electrode collector plate, wherein the negative electrode collector plate comprises: a central portion welded to a non-bonded portion of the negative electrode; a tab coupling portion extending from the central portion and coupled to a negative electrode tab provided in the electrode assembly; and a battery case coupling portion extending from the central portion and located between adjacent tab coupling portions, wherein the battery case coupling portion is interposed between the beading portion and the sealing gasket and fixed by the clamping portion. Claim 16 A secondary battery according to claim 15, wherein the battery case coupling portion of the negative electrode current collector plate comprises: a contact portion fixed by welding to the inner circumference of the beading portion adjacent to the clamping portion; and at least one bending portion having a changing direction of extension, and a connecting portion connecting the center portion and the contact portion. Claim 17 A secondary battery according to claim 15, wherein the negative electrode current collector plate includes a negative electrode current collector plate hole formed at a position corresponding to the hollow core portion of the electrode assembly, and the difference between the diameter of the negative electrode current collector plate hole and the diameter of the hollow core portion of the electrode assembly is 0.1 mm or more and 1 mm or less. Claim 18 A secondary battery according to claim 13, further comprising a positive current collector plate, wherein the positive current collector plate is welded to the non-positive portion of the positive, and at least a portion of the positive current collector plate is welded to the flat portion of the positive terminal. Claim 19 A secondary battery according to claim 18, further comprising an insulator interposed between the inner surface of the bottom portion of the positive current collector plate and the battery case; and between the inner surface of the battery case and the electrode assembly, wherein the insulator includes a welding hole that exposes the flat portion of the positive terminal toward the positive current collector plate and covers the surface of the positive current collector plate and one edge of the electrode assembly. Claim 20 A battery pack comprising at least one secondary battery according to paragraph 6. Claim 21 An automobile comprising at least one battery pack according to paragraph 20.

Images