Cylindrical secondary battery, battery pack including the same, and motor vehicle

Abstract

According to the present invention, a cylindrical secondary battery having a simple electrical connection structure with a through terminal and a positive electrode terminal and a negative electrode terminal positioned in the same direction can be obtained. Furthermore, since the cylindrical secondary battery of the present invention has a thin insulating coating layer on the inside wall of the battery can, it is possible to increase the capacity and improve the vibration characteristics.

Description

Technical Field

[0001] The present invention relates to a cylindrical secondary battery, a battery pack including the same, and a vehicle.

[0002] More specifically, the present invention relates to a cylindrical secondary battery having a structure in which both a positive electrode terminal and a negative electrode terminal are disposed on one side of the cylindrical secondary battery, and an insulating coating layer capable of efficiently insulating an electrode assembly and a current collector plate is formed on a battery can, a battery pack including the same, and a vehicle.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0025919 filed on Feb. 28, 2022, and all of the contents disclosed in the document of the Korean patent application are incorporated herein by reference.

Background Art

[0004] When manufacturing a battery pack using cylindrical secondary batteries, usually, a plurality of cylindrical secondary batteries are vertically arranged in a housing, and the upper and lower ends of the cylindrical secondary batteries are utilized as a positive electrode terminal and a negative electrode terminal, respectively, to electrically connect the plurality of cylindrical secondary batteries to each other.

[0005] That is, in a conventional cylindrical secondary battery, generally, the bottom surface of the battery can is used as a negative electrode terminal, and a top cap covering the upper end opening of the battery can is used as a positive electrode terminal.

[0006] However, when the positive electrode terminal and the negative electrode terminal of the cylindrical secondary battery are located on opposite sides of each other, electrical connection components such as a bus bar for electrically connecting the plurality of cylindrical secondary batteries must be applied to both the upper and lower portions of the cylindrical secondary battery. Further, as a result, components for insulation and components for ensuring waterproofness and airtightness need to be individually applied to the upper and lower portions of the battery pack, resulting in an increase in the number of applied components and a complication of the structure.

[0007] In order to eliminate such a complex structure, the applicant of the present application has proposed a cylindrical secondary battery structure in which the positive electrode terminal and the negative electrode terminal are applied in the same direction.

[0008] FIG. 1 is a schematic diagram showing a simplified upper structure of such a cylindrical secondary battery.

[0009] However, in FIG. 1, in order to insulate the electrode assembly 1 or a current collector plate (not shown) coupled thereto from the battery can 2, a cap (CAP)-shaped insulator 3 is applied. That is, the insulator 3 is in a form that completely wraps the current collector plate and the electrode assembly 1 in order to insulate the inner wall of the battery can 2 from the electrode assembly 1 and the like. The insulator 3 has side portions 3a interposed between the current collector plate / electrode assembly and the inner wall of the battery can on both sides thereof. In such a form, the volume of the electrode assembly 1 becomes smaller as the thickness of the side portion 3a is, so the capacity decreases. In addition, as the thickness of the side portion 3a is, the distance between the electrode assembly 1 and the battery can 2 is increased, so there is a problem that the vibration characteristics of the secondary battery deteriorate.

[0010] Therefore, it can be said that there is a demand for the development of a cylindrical secondary battery having an insulating structure capable of preventing such a decrease in capacity and deterioration of vibration characteristics.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention has been devised in consideration of the above-described problems, and is a cylindrical secondary battery having a structure in which a positive electrode terminal and a negative electrode terminal are applied in the same direction, and an object thereof is to provide a cylindrical secondary battery having an insulating structure capable of preventing a decrease in capacity and deterioration of vibration characteristics.

Means for Solving the Problem

[0013] A cylindrical secondary battery according to an embodiment of the present invention for solving the above problems includes an electrode assembly including a first electrode tab and a second electrode tab, a battery can housing the electrode assembly and electrically connected to the electrode assembly, a through terminal passing through one surface of the battery can and electrically connected to the electrode assembly, a first current collector plate having a first surface coupled to the first electrode tab and a second surface coupled to the through terminal, an insulator interposed between the first current collector plate and the battery can, and a cap plate covering an opening of the battery can, and an insulating coating layer is formed along an inner peripheral surface of a side wall of the battery can facing side portions of the first electrode tab and the first current collector plate.

[0014] The through terminal is electrically connected to the first electrode tab having a first polarity, and the battery can may be electrically connected to the second electrode tab having a second polarity different from the first polarity.

[0015] As an example, the through terminal may be located at a central portion of one surface of the battery can located on the opposite side of the opening.

[0016] Specifically, the through terminal may include a terminal exposed portion extending outside the battery can and a terminal insertion portion passing through an upper surface of the battery can.

[0017] The through terminal may be riveted to an inner surface of the battery can.

[0018] A central region of the terminal insertion portion may be coupled to the first current collector plate.

[0019] The through terminal may be coupled to the first current collector plate through the insulator.

[0020] As an example, the insulator may be formed in a flat plate shape having a through hole through which the through terminal passes.

[0021] The insulating coating layer may be formed to extend beyond the inner peripheral surface region of the side wall of the battery can facing the side portions of the first electrode tab and the first current collector plate and to the inner peripheral surface of the side wall of the battery can and / or the inner surface of the upper plate of the battery can.

[0022] As a specific example, the insulating coating layer may include one or more selected from the group consisting of epoxy, ceramics, and Teflon.

[0023] The cylindrical secondary battery may further include an insulating gasket interposed between the battery can and the through terminal to insulate the through terminal from the battery can.

[0024] Specifically, the insulating gasket may include a gasket exposed portion extending outside the battery can and a gasket insertion portion penetrating the upper surface of the battery can.

[0025] The cap plate may be provided with a venting portion configured to break and discharge gas when the internal pressure of the battery can increases to a certain level or more.

[0026] A battery pack according to an embodiment of the present invention may include a plurality of the cylindrical secondary batteries and a pack housing that houses the plurality of cylindrical secondary batteries.

[0027] An automobile according to an embodiment of the present invention may include the battery pack.

Advantages of the Invention

[0028] According to the present invention, a cylindrical secondary battery can be obtained in which the positive electrode terminal and the negative electrode terminal are located in the same direction and the electrical connection structure is simple.

[0029] Also, according to the present invention, since an insulating coating layer having a thin thickness is provided, an increase in capacity can be achieved and vibration characteristics can be improved.

[0030] However, the effects obtained by the present invention are not limited to the effects described above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

Brief Description of the Drawings

[0031] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later. Therefore, the present invention should not be construed as being limited only to the matters described in such drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0032] Hereinafter, the detailed configuration of the present invention will be described in detail with reference to the attached drawings and various embodiments. The embodiments described below are illustratively shown to assist in understanding the present invention, and the attached drawings are not illustrated at an actual scale to assist in understanding the invention, and the dimensions of some components may be exaggerated.

[0033] Since the present invention can be subjected to various modifications and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention.

[0034] The cylindrical secondary battery of the present invention includes an electrode assembly including a first electrode tab and a second electrode tab, a battery can accommodating the electrode assembly and electrically connected to the electrode assembly, a through terminal penetrating one surface of the battery can and electrically connected to the electrode assembly, a first current collector plate having a first surface coupled to the first electrode tab and a second surface coupled to the through terminal, an insulator interposed between the first current collector plate and the battery can, and a cap plate covering an opening of the battery can, and an insulating coating layer is formed along an inner circumferential surface of a side wall of the battery can facing side portions of the first electrode tab and the first current collector plate.

[0035] A battery pack according to an embodiment of the present invention may include a plurality of the cylindrical secondary batteries and may further include a pack housing for accommodating the plurality of cylindrical secondary batteries.

[0036] An automobile according to an embodiment of the present invention may include the battery pack.

[0037] Referring to FIGS. 2 to 4, a cylindrical secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 10, a battery can 20, a cap plate 30, a through terminal 40, a first current collector 60, and an insulator 70. In addition to the above-described components, the cylindrical secondary battery 100 may further include an insulating gasket 50 and / or a second current collector 80.

[0038] The electrode assembly 10 includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first electrode and the second electrode. The first electrode is a positive electrode or a negative electrode, and the second electrode corresponds to an electrode having a polarity opposite to that of the first electrode. The electrode assembly 10 may have, for example, a jelly-roll shape. That is, the electrode assembly 10 may be manufactured by winding a laminate formed by sequentially laminating the first electrode, the separator, and the second electrode at least once around a winding center C. In this case, an additional separator may be provided on the outer peripheral surface of the electrode assembly 10 for insulation from the battery can 20.

[0039] The first electrode includes a first electrode active material applied on one or both surfaces of a first electrode current collector. At one end portion in the width direction (a direction parallel to the Z-axis) of the first electrode current collector, there is a plain portion where the first electrode active material is not applied. The plain portion functions as a first electrode tab 11. The first electrode tab 11 is provided at an upper portion in the height direction (a direction parallel to the Z-axis) of the electrode assembly 10 housed in the battery can 20.

[0040] The second electrode includes a second electrode active material applied on one or both surfaces of a second electrode current collector. At the other end portion in the width direction (a direction parallel to the Z-axis) of the second electrode current collector, there is a plain portion where the second electrode active material is not applied. The plain portion functions as a second electrode tab 12. The second electrode tab 12 is provided at a lower portion in the height direction of the electrode assembly 10 housed in the battery can 20.

[0041] In the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate can be used without limitation as long as they are active materials known in the art.

[0042] In one example, the positive electrode active material may contain an alkali metal compound represented by the general chemical formula A[A X M Y O 2+Z (A contains at least one or more elements among Li, Na, and K; M contains at least one or more elements selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Sc, Ru, and Cr; x ≧ 0, 1 ≦ x + y ≦ 2, -0.1 ≦ z ≦ 2: The stoichiometric coefficients of x, y, z, and the components contained in M are selected so that the compound maintains electrical neutrality).

[0043] Preferably, the positive electrode active material may contain primary particles and / or secondary particles formed by aggregation of the primary particles.

[0044] In one example, as the negative electrode active material, a carbon material, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, low-crystalline carbon, highly crystalline carbon, etc. can all be used.

[0045] The separator can be used alone or in a laminated form a porous polymer film, for example, a porous polymer film made from polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer, etc. As another example, the separator can use a normal porous non-woven fabric, for example, a non-woven fabric such as high-melting-point glass fiber and polyethylene terephthalate fiber.

[0046] At least one surface of the separator may include a coating layer of inorganic particles.

[0047] In addition, the separation membrane itself can also consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that an interstitial volume exists between adjacent particles.

[0048] The electrolyte can be a salt having a structure such as A + B -- . Here, A + includes ions composed of alkali metal cations such as Li + , Na + , K + and combinations thereof. And B -- is F -- , Cl -- , Br -- , I -- , NO3 -- , N(CN)2 -- , BF4 -- , ClO4 -- , AlO4 -- , AlCl4 -- , PF6 -- , SbF6 -- , AsF6 -- , BF2C2O4 -- , BC4O8 -- , (CF3)2PF4 -- , (CF3)3PF3 - , (CF3)4PF2 -- , (CF3)5PF -- , (CF3)6P -- , CF3SO3 -- , C4F9SO3 -- , CF3CF2SO3 -- , (CF3SO2)2N -- , (FSO2)2N -- , CF3CF2(CF3)2CO -- , (CF3SO2)2CH -- , (SF5)3C -- , (CF3SO2)3C -- , CF3(CF2)7SO3 -- , CF3CO2 -- , CH3CO2 - , SCN --, and (CF3CF2SO2)2N -- contains any one or more anions selected from the group consisting of

[0049] The electrolyte can also be used by dissolving it in an organic solvent.

[0050] Referring to FIGS. 2 to 4, the battery can 20 is a substantially cylindrical container having an opening formed therein below, and is made of, for example, a conductive metal material. The bottom of the battery can 20 provided with the opening is referred to as an opened end. The side surface (outer peripheral surface) and the upper surface of the battery can 20 can be integrally formed. The upper surface of the battery can 20 (a surface parallel to the X-Y plane) has a substantially flat form. The upper surface located on the opposite side of the opening (or opened end) is referred to as a closed end. The battery can 20 houses the electrode assembly 10 through the opening formed below, and also houses the electrolyte together.

[0051] The battery can 20 is electrically connected to the electrode assembly 10. The battery can 20 is electrically connected to, for example, the second electrode tab 12 of the electrode assembly 10.

[0052] In this case, the battery can 20 has the same polarity as the second electrode tab 12.

[0053] Referring to FIGS. 3 and 8, the battery can 20 may include a beading portion 21 and a crimping portion 22 formed at the lower end. The beading portion 21 has a form in which the outer peripheral edge of the battery can 20 is press-fitted to a predetermined depth. The beading portion 21 is formed at the lower part of the electrode assembly 10. The beading portion 21 can function as a support portion on which the electrode assembly 10 having a size substantially corresponding to the width of the battery can 20 does not come out through the opening formed at the lower end of the battery can 20, and to which the cap plate 30 is seated.

[0054] The crimping portion 22 is formed at the lower part of the beading portion 21. The crimping portion 22 has a form that extends and bends so as to wrap the outer peripheral surface and the lower surface of the cap plate 30 disposed below the beading portion 21.

[0055] However, the present invention does not exclude the case where the battery can 20 does not include such a beading portion 21 and / or crimping portion 22. In the present invention, when the battery can 20 does not include the beading portion 21 and / or crimping portion 22, the fixing of the electrode assembly 10 and / or the fixing of the cap plate 30 and / or the sealing of the battery can 20 can be achieved, for example, by additional application of a component that can function as a stopper for the electrode assembly 10 and / or additional application of a structure to which the cap plate 30 can be seated and / or welding between the battery can 20 and the cap plate 30.

[0056] Referring to FIGS. 3 and 8, the cap plate 30 can be made of, for example, a metal material in order to ensure rigidity. The cap plate 30 covers an opening (or open end) formed at the lower end of the battery can 20. That is, the cap plate 30 forms the lower surface of the cylindrical secondary battery 100. In the cylindrical secondary battery 100 of the present invention, the cap plate 30 has no polarity even when it is made of a conductive metal material. Having no polarity may mean that the cap plate 30 is electrically insulated from the battery can 20 and the through terminal 40. Therefore, the cap plate 30 does not function as a positive electrode terminal or a negative electrode terminal. Therefore, the cap plate 30 does not need to be electrically connected to the electrode assembly 10 and the battery can 20, and its material does not necessarily need to be a conductive metal.

[0057] When the battery can 20 of the present invention includes a beading portion 21, the cap plate 30 can be seated on the beading portion 21 formed on the battery can 20. Further, when the battery can 20 of the present invention includes a crimping portion 22, the cap plate 30 is fixed by the crimping portion 22. An airtight gasket 90 can be interposed between the cap plate 30 and the crimping portion 22 of the battery can 20 to ensure the airtightness of the battery can 20.

[0058] On the other hand, as described above, the battery can 20 of the present invention may not include the beading portion 21 and / or the crimping portion 22. In this case, the airtight gasket 90 can be interposed between the fixing structure provided on the opening side of the battery can 20 and the cap plate 30 to ensure the airtightness of the battery can 20.

[0059] Referring to FIG. 8, the cap plate 30 may further include a venting portion 31 formed to prevent the internal pressure from increasing beyond a preset value due to the gas generated inside the battery can 20. The venting portion 31 corresponds to a region having a thickness thinner than that of the peripheral region of the cap plate 30. The venting portion 31 is structurally weaker than the peripheral region. Therefore, when an abnormality occurs in the cylindrical secondary battery 100 and the internal pressure of the battery can 20 increases above a certain level, the venting portion 31 is broken and the gas generated inside the battery can 20 is discharged. The venting portion 31 can be formed, for example, by notching on one or both surfaces of the cap plate 30 to partially reduce the thickness of the battery can 20.

[0060] The cylindrical secondary battery 100 according to an embodiment of the present invention has a structure in which both a positive electrode terminal and a negative electrode terminal are present at the upper part. Therefore, the upper structure is more complicated than the lower structure. Thus, in order to smoothly discharge the gas generated inside the battery can 20, a venting portion 31 may be formed on a cap plate 30 forming the lower surface of the cylindrical secondary battery 100. As illustrated in FIG. 8, the lower end portion of the cap plate 30 is preferably positioned further upward than the lower end portion of the battery can 20. In this case, even if the lower end portion of the battery can 20 hits the ground or hits the bottom surface of a housing for module or pack configuration, the cap plate 30 does not hit the ground or the bottom surface of a housing for module or pack configuration. Therefore, due to the weight of the cylindrical secondary battery 100, a phenomenon in which the pressure required for breaking of the venting portion 31 is different from the design value can be prevented, and thereby, the breakage smoothness of the venting portion 31 can be ensured.

[0061] Referring to FIGS. 2 to 4, the through terminal 40 is made of a conductive metal material and passes through the upper surface of the battery can 20, that is, the surface (a surface parallel to the X-Y plane) located on the opposite side of the opening of the battery can 20. The through terminal 40 is electrically connected to, for example, the first electrode tab 11 of the electrode assembly 10. In this case, the through terminal 40 has a first polarity. Therefore, the through terminal 40 can function as a first electrode terminal in the cylindrical secondary battery 100 of the present invention. When the through terminal 40 has such a first polarity, the through terminal 40 is electrically insulated from the battery can 20 having a second polarity. The electrical insulation between the through terminal 40 and the battery can 20 can be realized in various ways. For example, insulation can be realized by interposing an insulating gasket 50 between the through terminal 40 and the battery can 20.

[0062] The above through terminal 40 includes a terminal exposed portion 41 and a terminal insertion portion 42. The above terminal exposed portion 41 is exposed outside the battery can 20. The above terminal exposed portion 41 may be located at substantially the center of the upper surface of the battery can 20. The maximum width of the above terminal exposed portion 41 may be formed to be even larger than the maximum width of the hole formed in the battery can 20 due to the penetration of the through terminal 40. The above terminal insertion portion 42 penetrates substantially the center of the upper surface of the battery can 20 and can be electrically connected to the first electrode tab 11. The peripheral region of the above terminal insertion portion 42 can be rivet - coupled to the inner surface of the battery can 20. That is, the peripheral region of the above terminal insertion portion 42 may have a form bent toward the inner surface of the battery can 20, whereby the maximum width of the end of the terminal insertion portion 42 can be formed to be even larger than the maximum width of the hole of the battery can 20 formed by the penetration of the terminal insertion portion 42.

[0063] On the other hand, the cylindrical secondary battery 100 of the present invention includes a first current collector 60. The first surface of the above first current collector 60 is coupled to the first electrode tab 11, and the second surface is coupled to the above through terminal 40. In this case, the central region of the terminal insertion portion 42 of the above through terminal 40 can be coupled to the second surface (upper surface) of the above first current collector 60. The central region of the above terminal insertion portion 42 may have, for example, a substantially cylindrical shape. The diameter of the bottom surface of the central region of the above terminal insertion portion 42 can be set to about 6.2 mm.

[0064] The connection between the bottom surface of the central region of the above terminal insertion portion 42 and the first current collector 60 can be performed, for example, by laser welding or ultrasonic welding.

[0065] The above laser welding can be performed by irradiating a laser through a hole formed at the winding center C of the electrode assembly 10 to form a laser welding line on one surface of the first current collector 60.

[0066] In one embodiment of the present invention, the upper surface of the battery can 20 and the through terminal 40 exposed outside the battery can 20 have opposite polarities and face the same direction. Further, a step may be formed between the through terminal 40 and the upper surface of the battery can 20. Specifically, when the entire upper surface of the battery can 20 has a flat shape or a shape protruding upward from its central portion, the terminal exposed portion 41 of the through terminal 40 can protrude further above the upper surface of the battery can 20. Conversely, when the upper surface of the battery can 20 has a concave shape that is recessed downward from its central portion, that is, in the direction toward the electrode assembly 10, the upper surface of the battery can 20 can protrude further above the terminal exposed portion 41 of the electrode terminal 40.

[0067] On the other hand, when the upper surface of the battery can 20 has a concave shape that is recessed downward from its central portion, that is, in the direction toward the electrode assembly 10, depending on the depth of the recess and the thickness of the terminal exposed portion 41 of the electrode terminal 40, the upper surface of the battery can 20 and the upper surface of the terminal exposed portion 41 can be in the same plane. In this case, a step may not be formed between the upper surface of the battery can 20 and the terminal exposed portion 41.

[0068] The insulating gasket 50 is interposed between the battery can 20 and the through terminal 40 to prevent the battery can 20 and the through terminal 40 having opposite polarities from coming into contact with each other. Thereby, the upper surface of the battery can 20 having a substantially flat shape can function as the second electrode terminal of the cylindrical secondary battery 100.

[0069] The insulating gasket 50 includes a gasket exposed portion 51 and a gasket insertion portion 52. The gasket exposed portion 51 is interposed between the terminal exposed portion 41 of the through terminal 40 and the battery can 20. The gasket insertion portion 52 is interposed between the terminal insertion portion 42 of the through terminal 40 and the battery can 20. The gasket insertion portion 52 can be deformed together during the riveting of the terminal insertion portion 42 and can be in close contact with the inner surface of the battery can 20. The insulating gasket 50 can be made of, for example, an insulating resin material.

[0070] When the insulating gasket 50 is made of a resin material, the insulating gasket 50 can be joined to the battery can 20 and the through terminal 40 by heat fusion. In this case, the airtightness at the joining interface between the insulating gasket 50 and the through terminal 40 and at the joining interface between the insulating gasket 50 and the battery can 20 can be enhanced.

[0071] Among the upper surface of the battery can 20, the entire remaining area excluding the area occupied by the through terminal 40 and the insulating gasket 50 corresponds to the second electrode terminal 20a having a polarity opposite to that of the through terminal 40.

[0072] The cylindrical side wall of the battery can 20 can be formed integrally (one piece) with the second electrode terminal 20a so that there is no discontinuous portion between them. The connection from the side wall of the battery can 20 to the second electrode terminal 20a can be a smooth curve. However, the present invention is not limited to this, and the connection portion may include at least one angle having a predetermined angle.

[0073] Referring to FIGS. 3 and 4, the first current collector plate 60 is joined to the upper part of the electrode assembly 10. The first current collector plate 60 is made of a conductive metal material and is connected to the first electrode tab 11. Although not shown in the drawings, the first current collector plate 60 may be provided with a plurality of irregularities formed radially on its lower surface. When the irregularities are formed, the first current collector plate 60 can be pressed to press the irregularities into the first electrode tab 11.

[0074] Although not shown, the first current collector plate 60 can be joined to a joining surface formed by bending the end of the first electrode tab 11 in a direction parallel to the first current collector plate 60. The bending direction of the first electrode tab 11 can be, for example, a direction toward the winding center C of the electrode assembly 10. When the first electrode tab 11 has such a bent form, the space occupied by the first electrode tab 11 is reduced, which can lead to an improvement in energy density. In addition, an increase in the joining area between the first electrode tab 11 and the first current collector plate 60 can bring about an improvement in the joining force and a resistance reduction effect.

[0075] Referring to FIGS. 3 and 4, the insulator 70 is provided between the first current collector plate 60 coupled to the upper part of the electrode assembly 10 and the inner surface of the battery can 20. The insulator 70 prevents contact between the first current collector plate 60 and the battery can 20.

[0076] On the other hand, as shown in FIG. 1, when the insulator is formed in a cap shape having a side portion 3a interposed between the upper end of the outer peripheral surface of the electrode assembly and the inner surface of the battery can, contact between the first electrode tab and the battery can can be prevented. However, in this case, the capacitance may decrease due to the thickness of the side wall of the insulator by the side portion, and the vibration characteristics may deteriorate.

[0077] Therefore, in the present invention, the insulator is formed, for example, in a flat plate shape without a side portion, and only contact between the first current collector plate 60 and the battery can 20 is prevented.

[0078] The first current collector plate 60 may be a plate extending completely across the upper end of the outer peripheral surface of the electrode assembly 10. However, the present invention is not limited to this, and the first current collector plate 60 may also be formed so as to extend only partially across the upper end of the outer peripheral surface of the electrode assembly 10.

[0079] In the cylindrical secondary battery 100 according to an embodiment of the present invention, the terminal insertion portion 42 of the through terminal 40 may pass through the insulator 70 and be coupled to the first current collector plate 60. The insulator 70 may have an opening adjacent to the winding center C. Through the opening, the terminal insertion portion 42 of the through terminal 40 can be in direct contact with the first current collector plate 60.

[0080] In the present invention, in order to increase the capacity and improve the vibration characteristics, an insulating coating layer 23 is formed along the inner peripheral surface of the side wall of the battery can 20 facing the side portions of the first electrode tab 11 and the first current collector plate 60. That is, as shown in FIG. 1, instead of having a thick insulator side portion facing the side portions of the battery can, the first electrode tab, and the first current collector plate, a thin insulating coating layer 23 is formed on the battery can, thereby replacing the insulating function of the cap-shaped insulator. For example, the thickness of the side portion 3a of the insulator in FIG. 1 is 0.3t (0.3 mm), and when the thicknesses of the side portions on both sides are combined, it becomes 0.6 mm. That is, as the thickness increases, the width of the electrode assembly in the cylindrical secondary battery 100 decreases, resulting in a decrease in the battery capacity. Further, since the thick side portion 3a is interposed between the electrode assembly and the battery can, when vibration is applied, the vibration characteristics deteriorate, such as an increase in vibration.

[0081] On the other hand, as shown in FIGS. 3 and 4, when the insulating coating layer 23 is formed in the inner peripheral surface region of the side wall of the battery can 20 facing the side portions of the first electrode tab 11 and the first current collector plate 60, the thickness of the insulating coating layer 23 can be determined in the range of about 3 to 100 μm. In this way, the insulating coating layer 23 has a much thinner thickness compared to the insulator in FIG. 1, and the width of the electrode assembly 10 can be further increased accordingly, so that the battery capacity can be increased. Also, the vibration characteristics of the cylindrical secondary battery 100 are further improved.

[0082] The insulating coating layer 23 may include, but is not limited to, one or more selected from the group consisting of epoxy, ceramics, and Teflon. For example, the insulating coating layer 23 can be formed using other materials that can be used for electrical insulation between other metal bodies in a metal battery can.

[0083] Such an insulating coating layer 23 can be applied to the inner wall of the battery can by, for example, a spray method, and other suitable coating methods are also applicable.

[0084] FIG. 5 is a partial cross-sectional view showing the formation position of the insulating coating layer which is a main part of the present invention, and FIGS. 6 and 7 are partial cross-sectional views showing other examples of the formation position of the insulating coating layer which is a main part of the present invention.

[0085] In FIGS. 5 to 7, for the purpose of clearly showing the formation position of the insulating coating layer, the illustration of the insulator, the first current collector plate, and the electrode assembly is omitted.

[0086] Referring to FIG. 5, the insulating coating layer 23 is basically formed in a region facing the side portion of the first electrode tab 11 and the side portion of the first current collector plate 60. That is, if the insulator 70 insulates between the upper portion of the first current collector plate 60 and the battery can 20, the insulating coating layer 23 insulates between the side portion of the first current collector plate 60 and the battery can 20. Therefore, the upper region of the insulating coating layer 23 must be a region including at least the side portion of the first current collector plate 60. In order to more surely insulate between the first current collector plate 60 and the battery can 20, as shown in FIG. 6, the insulating coating layer 23 can be formed by expanding beyond the region facing the first current collector plate 60.

[0087] In addition, the insulating coating layer 23 is coated along the inner peripheral surface of the side wall of the battery can facing the side portion (the outer peripheral portion of the first electrode tab) of the first electrode tab 11 in order to insulate between the side portion of the first electrode tab 11 and the battery can 20. Therefore, the lower region of the insulating coating layer 23 must be a region including at least the side portion of the first electrode tab 11. In order to more surely insulate between the first electrode tab 11 and the battery can 20, basically, it is preferable that the lower region of the insulating coating layer 23 is formed beyond the region facing the first electrode tab 11 (see FIGS. 4 and 5).

[0088] On the other hand, in order to more surely insulate the first current collector 60 and the battery can 20, as shown in FIG. 7, it is also possible to form the insulating coating layer 23 by expanding up to the inner side surface of the upper plate of the battery can beyond the inner peripheral surface region of the side wall of the battery can 20. However, in this case, since welding must be performed on the rivet joint portion of the through terminal 40, it is necessary to form the insulating coating layer only on the inner side surface of the battery can 20 excluding this rivet joint portion.

[0089] The height of the insulating coating layer 23 can be determined according to the size of the battery, the current collector, and the height of the electrode tab. For example, as one embodiment, the height of the insulating coating layer 23 can be determined within a range of 5 mm or less. However, in order to obtain an insulating effect, the height of the insulating coating layer 23 is preferably 2 mm or more.

[0090] As shown in FIGS. 5 to 7, when the electrode assembly 10, the first current collector 60, the through terminal 40, etc. described above are coupled to the battery can 20 in a state where the insulating coating layer 23 is previously applied to a predetermined position on the inner side wall of the battery can 20, the cylindrical secondary battery 100 of the present invention can be easily manufactured.

[0091] Referring to FIGS. 3 and 8, the second current collector 80 is coupled to the lower part of the electrode assembly 10. The second current collector 80 is made of a conductive metal material and is connected to the second electrode tab 12. Further, the second current collector 80 is electrically connected to the battery can 20. The second current collector 80 can be interposed and fixed between the inner side surface of the battery can 20 and the airtight gasket 90 as shown in FIG. 8. Alternatively, the second current collector 80 can also be welded to the inner wall surface of the battery can 20.

[0092] Although not shown, the second current collector 80 can be coupled to a coupling surface formed by bending the end of the second electrode tab 12 in a direction parallel to the second current collector 80. The bending direction of the second electrode tab 12 can be, for example, a direction toward the winding center C of the electrode assembly 10. When the second electrode tab 12 has such a bent form, the space occupied by the second electrode tab 12 is reduced, which can lead to an improvement in energy density. In addition, an increase in the coupling area between the second electrode tab 12 and the second current collector 80 can bring about an improvement in the coupling force and a resistance reduction effect.

[0093] Referring to FIGS. 3 and 4, a cylindrical secondary battery 100 according to an embodiment of the present invention includes a through terminal 40 having a first polarity on one side in its longitudinal direction (a direction parallel to the Z axis), and a second electrode terminal 20a that is electrically insulated from the through terminal 40 and has a second polarity. That is, in the cylindrical secondary battery 100 according to an embodiment of the present invention, since the pair of electrode terminals 40 and 20a are located in the same direction, when a plurality of cylindrical secondary batteries 100 are electrically connected, electrical connection components such as a bus bar can be arranged only on one side of the cylindrical secondary battery 100. This can lead to a simplification of the battery pack structure and an improvement in energy density.

[0094] In addition, the cylindrical secondary battery 100 has a structure in which one surface of the battery can 20 having a substantially flat form can be used as the second electrode terminal 20a, so that a sufficient bonding area can be ensured when an electrical connection component such as a bus bar is joined to the second electrode terminal 20a. As a result, the cylindrical secondary battery 100 can ensure sufficient bonding strength between the electrical connection component and the second electrode terminal 20a and can reduce the resistance at the bonding site to a preferable level.

[0095] In addition, the cylindrical secondary battery 100 of the present invention can form a thin insulating coating layer 23 on the inner wall of the battery can, and can increase the width of the electrode assembly 10 facing it, so that the capacity of the battery can be increased and the deterioration of the vibration characteristics can be prevented.

[0096] Further, the cylindrical secondary battery 100 of the present invention relates to a so-called tab-less type cylindrical battery in which the first current collector plate 60 is directly connected to the through terminal 40 and no tab is required. Conventional cylindrical secondary batteries generally have a structure in which a tab connecting a jelly roll type electrode assembly and an external terminal is welded to the foil of the jelly roll electrode assembly for connection. In a cylindrical secondary battery having such a structure, the current path is limited, and it is inevitable that the self-resistance of the jelly roll becomes extremely high. Thus, a method of increasing the number of tabs connecting the jelly roll and the external terminal to reduce the resistance has been attempted, but simply increasing the number of tabs in this way has limitations in reducing the resistance to a desired level and sufficiently securing the current path. As shown in FIGS. 3 and 4, the present invention directly connects the first current collector plate 60 to the through terminal 40, thereby electrically connecting the first current collector plate and the through terminal without a tab and solving the conventional problems. Further, by insulating the space between the first current collector plate, which has a high possibility of generating heat, and the battery can with the above-described insulating coating layer 23, there is an advantage that the safety of the battery can be improved.

[0097] Preferably, the cylindrical battery cell can be, for example, a cylindrical battery cell having a form factor ratio (defined as the value obtained by dividing the diameter of the cylindrical battery cell by the height, i.e., the ratio of the diameter (Φ) to the height (H)) greater than about 0.4.

[0098] Here, the form factor means a value indicating the diameter and height of the cylindrical battery cell. The cylindrical battery cell according to an embodiment of the present invention can be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 represents that the cross section of the cell is circular.

[0099] A battery cell according to an embodiment of the present invention can be a cylindrical battery cell that is substantially cylindrical, has a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0100] A battery cell according to another embodiment can be a cylindrical battery cell that is substantially cylindrical, has a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of about 0.640.

[0101] A battery cell according to another embodiment can be a cylindrical battery cell that is substantially cylindrical, has a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of about 0.418.

[0102] A battery cell according to another embodiment can be a cylindrical battery cell that is substantially cylindrical, has a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of about 0.600.

[0103] A battery cell according to another embodiment can be a cylindrical battery cell that is substantially cylindrical, has a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of about 0.575.

[0104] Conventionally, battery cells with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of 18650 cells, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is about 0.277.

[0105] In the case of 21700 cells, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is about 0.300.

[0106] Referring to FIG. 9, a battery pack 300 according to an embodiment of the present invention includes an assembly of secondary batteries 100 in which a plurality of cylindrical secondary batteries according to an embodiment of the present invention as described above are electrically connected, and a pack housing 200 that houses the same. In the drawings of the present invention, for the convenience of illustration, components such as bus bars, cooling units, and power terminals for electrical connection are omitted.

[0107] Referring to FIG. 10, a vehicle 500 according to an embodiment of the present invention can be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 300 according to an embodiment of the present invention. The vehicle 500 includes four-wheel vehicles and two-wheel vehicles. The vehicle 500 operates by being supplied with power from a battery pack 300 according to an embodiment of the present invention.

[0108] As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereby, and it goes without saying that various modifications and variations are possible within the scope of the technical idea of the present invention and the equivalent scope of the claims described below by those having ordinary knowledge in the technical field to which the present invention pertains.

Description of Reference Numerals

[0109] 10: Electrode assembly C: Winding center 11: First electrode tab 12: Second electrode tab 20: Battery can 21: Beading portion 22: Crimping portion 23: Insulating coating layer 30: Cap plate 31: Venting portion 40: Through terminal 41: Terminal exposed portion 42: Insertion portion 50: Insulating gasket 60: First current collector 70: Insulator 80: Second current collector 90: Hermetic gasket 100: Cylindrical secondary battery 200: Pack housing 300: Battery pack 500: Automobile

Claims

1. An electrode assembly including a first electrode tab and a second electrode tab; A battery can that houses the electrode assembly and is electrically connected to the electrode assembly, the battery can having a first end face with an opening formed therein and a second end face located on the side opposite to the first end face; A through terminal that penetrates the second end face of the battery can and is electrically connected to the electrode assembly; A first current collector plate having a first surface coupled to the first electrode tab and a second surface coupled to the through terminal; An insulator interposed between the first current collector plate and the battery can; A cap plate covering the opening of the first end face of the battery can, including; A cylindrical secondary battery in which an insulating coating layer is formed along the inner circumferential surface of the side wall of the battery can facing the side portions of the first electrode tab and the first current collector plate.

2. The through terminal is electrically connected to the first electrode tab having a first polarity; The battery can is electrically connected to the second electrode tab having a second polarity different from the first polarity; The cylindrical secondary battery according to Claim 1.

3. An electrode assembly including a first electrode tab and a second electrode tab; A battery can that houses the electrode assembly and is electrically connected to the electrode assembly; A through terminal that penetrates one end face of the battery can and is electrically connected to the electrode assembly; A first current collector plate having a first surface coupled to the first electrode tab and a second surface coupled to the through terminal; An insulator interposed between the first current collector plate and the battery can; A cap plate covering the opening of the battery can, including; An insulating coating layer is formed along the inner circumferential surface of the side wall of the battery can facing the side portions of the first electrode tab and the first current collector plate; The through terminal is located at the center of one end face of the battery can located on the side opposite to the opening, a cylindrical secondary battery.

4. The through terminal; A terminal exposed portion extended outside the battery can; A terminal insertion portion penetrating the upper surface of the battery can, the cylindrical secondary battery according to Claim 1.

5. The through terminal; The cylindrical secondary battery according to Claim 1, which is riveted and coupled to the inner surface of the battery can.

6. The central region of the terminal insertion portion is coupled to the first current collector plate, the cylindrical secondary battery according to Claim 4.

7. The through terminal; The cylindrical secondary battery according to Claim 1, which passes through the insulator and is coupled to the first current collector plate.

8. The cylindrical secondary battery according to claim 7, wherein the insulator is formed in a flat plate shape having a through hole through which the through terminal passes.

9. The cylindrical secondary battery according to claim 1, wherein the insulating coating layer is formed to extend to the inner peripheral surface of the side wall of the battery can and / or the inner surface of the upper plate of the battery can beyond the inner peripheral surface region of the side wall of the battery can facing the side portions of the first electrode tab and the first current collector plate.

10. The cylindrical secondary battery according to claim 1, wherein the insulating coating layer contains one or more selected from the group consisting of epoxy, ceramics, and Teflon (registered trademark).

11. The cylindrical secondary battery further includes an insulating gasket interposed between the battery can and the through terminal to insulate the through terminal and the battery can, the cylindrical secondary battery according to claim 1.

12. The insulating gasket includes a gasket exposed portion extending outside the battery can, and a gasket insertion portion penetrating the upper surface of the battery can, the cylindrical secondary battery according to claim 11.

13. The cap plate is provided with a venting portion configured to break and discharge gas when the internal pressure of the battery can increases to a certain level or more, the cylindrical secondary battery according to claim 1.

14. A plurality of cylindrical secondary batteries according to any one of claims 1 to 13, and a pack housing for housing the plurality of cylindrical secondary batteries, a battery pack.

15. An automobile including the battery pack according to claim 14.

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