Battery cell having structure for preventing side wall member of can from rupturing

Abstract

The present invention provides a battery cell capable of preventing a side wall portion of a can from rupturing during thermal runaway. The battery cell comprises: a can including a side wall member extending in an axial direction and an open end portion provided at one axial end portion of the side wall member; a cap covering the open end portion; an electrode assembly accommodated in the can; and a current collection plate electrically connecting the electrode assembly and the can. An edge of the cap is bonded to the one axial end portion of the side wall member. The cap is provided with a rupture-inducing portion having a loop shape concentric with the edge of the cap. The current collection plate comprises: a main body portion connected to an electrode tab of the electrode assembly; a loop shaped can connection portion which is arranged centrifugally relative to the main body portion and is bonded to at least one of the side wall member or the cap; and a bridge which extends radially, and of which the centripetal side is connected to the main body portion and the centrifugal side is connected to the can connection portion. The rupture-inducing portion of the cap is disposed further outward in the radial direction than the centripetal edge of the can connection portion.

Description

Battery cell having a structure to prevent damage to the side wall member of the can

[0001] The present invention relates to a battery cell capable of preventing the side wall of a can from being damaged during thermal runaway.

[0002] This application claims priority to Korean Application No. 10-2023-0182390, filed December 14, 2023, and Korean Application No. 10-2024-0114839, filed August 27, 2024, the entire contents of which are incorporated herein by reference.

[0003] With the expansion of the electric vehicle market, demand for high-capacity, high-voltage cylindrical lithium-ion batteries is increasing. This, in turn, is fueling growing demands for battery safety. Typically, cylindrical batteries have a notch on the surface of the cap to prevent damage before thermal runaway occurs due to abnormal operation.

[0004] Meanwhile, despite the high explosive potential of high-capacity and high-voltage cells, achieving high battery capacity also requires a significant reduction in the thickness of the battery can's sidewall components. Consequently, the pressure and flame generated by thermal runaway are highly likely to damage the can's sidewall components.

[0005] The process of manufacturing a battery cell using a cylindrical can includes the steps of deep drawing a metal sheet to form a circular bottom portion and a circular tubular side wall member connected thereto, accommodating an electrode assembly therein, and then closing the open end of the side wall member with a cap.

[0006] Meanwhile, at one of the axial ends of the electrode assembly facing the open end, a current collector plate is provided that contacts and is electrically connected to the electrode tab of the electrode assembly. The current collector plate is connected to the cap or the side wall member by welding or the like so that it contacts and is electrically connected to the cap or the side wall member.

[0007] Referring to Fig. 23, in closing the open end of the cylindrical can (10), first, with the electrode assembly (20) housed inside the can (10), a predetermined section of the side wall member located axially outer than the electrode assembly is concavely beaded toward the center to form a beading portion (117). Next, the current collector plate (32) is connected to the beading portion (117). Then, with the edge of the cap (16) placed on top of the beading portion (117), the axial end of the side wall member is crimped toward the center to secure it. A gasket (169) is interposed between the edge of the cap and the side wall member to seal the space between the cap and the side wall member.

[0008] Meanwhile, the cap is provided with a loop-shaped breakage inducing part (165) that causes breakage when thermal runaway of the battery cell occurs and the internal pressure of the can increases, thereby allowing gas and flames generated during thermal runaway to be discharged.

[0009] However, as explained above, when applying a crimping structure to secure the cap to the can, it is difficult to secure the diameter (D1) of the breakage inducing portion because the crimping portion (118) extends toward the center. In other words, the diameter (D1) of the breakage inducing portion cannot but be smaller than the inner diameter of the tip of the crimping portion (118).

[0010] In contrast, due to the structural characteristics that require the cap (16) to be fixed, the inner diameter (D2) of the recessed portion of the beading portion (117) is similar to or slightly smaller than the inner diameter of the crimping portion. Therefore, when thermal runaway occurs and the damage inducing portion (165) is damaged and venting occurs, as illustrated in FIG. 24, a type of bottleneck phenomenon (A, B) occurs due to the venting passage being smaller than the inner diameter (D2) of the beading portion (117), and as a result, there is a possibility that the flame may damage the beading portion (117), resulting in damage to the side wall.

[0011] If a single cell in an electric vehicle module or pack experiences thermal runaway and a sidewall member fails, it could affect adjacent cells, potentially leading to thermal runaway throughout the entire battery pack system. Therefore, sidewall member failure in cylindrical lithium-ion batteries poses a direct threat to user safety, and a structure capable of preventing this is critically needed.

[0012] The present invention has been devised to solve the above-described problem, and aims to provide a battery cell having a structure capable of preventing a side wall member of a battery can from being damaged even if thermal runaway occurs.

[0013] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0014] The present invention, which aims to solve the above-described problem, can be applied to a battery cell including an electrode assembly, a can that accommodates the electrode assembly, and a cap that closes and seals an open end of the can.

[0015] The can includes a side wall member extending in an axial direction, and an open end provided at one axial end of the side wall member.

[0016] The edge of the cap is joined to the axial end of the side wall member. In addition, the cap is provided with a loop-shaped breakage inducing portion concentric with the edge of the cap.

[0017] The above current collector plate includes a main body portion connected to the electrode tab of the electrode assembly; a loop-shaped can connection portion disposed on a centrifugal side relative to the main body portion and joined to at least one of the side wall member and the cap; and a bridge having a centrifugal side connected to the main body portion and a centrifugal side connected to the can connection portion and extending in a radial direction; wherein the breakage inducing portion of the cap is disposed radially further outward than the centrifugal edge of the can connection portion.

[0018] By joining the axial end of the side wall member and the radial end of the cap without a crimping process that plastically deforms one axial end of the side wall member toward the center, the diameter of the failure inducing portion can be secured to be larger.

[0019] The ratio of the diameter of the breakage inducing portion to the diameter of the battery cell may be 38 / 46 or greater. More preferably, the ratio may be 40 / 46 or greater.

[0020] The above cap and side wall member can be joined by welding, brazing or soldering.

[0021] A floor member is connected to the other axial end of the side wall member, and thus the other axial end of the side wall member can form a closed end.

[0022] The above electrode assembly may be in the form of a jelly-roll wound around a predetermined axis.

[0023] A current collector plate can be electrically connected to the above electrode assembly.

[0024] An electrode tab is provided at one of the axial ends of the electrode assembly corresponding to the open end, and the current collector plate can be electrically connected to the electrode tab.

[0025] The above-mentioned current collector plate may include a main body that is electrically connected to the electrode tab.

[0026] The above main body part may include an electrode tab connecting part that is connected to the electrode tab.

[0027] The connection between the electrode tab connection portion and the electrode tab can be achieved by welding, brazing, or soldering. Preferably, the connection can be achieved by laser welding, which irradiates a laser onto the surface of the electrode tab connection portion.

[0028] The above main body part may include an inner part connected to the electrode tab connection part on the center side of the electrode tab connection part.

[0029]

[0030] The above can connection portion and the above main body portion can be electrically connected.

[0031] The above body part may be positioned axially further inward than the can connection part. That is, the can connection part may be positioned axially further outward than the above body part.

[0032] The can portion that is positioned radially further outward than the above-mentioned breakage inducing portion may be positioned axially further outward than the can connection portion of the above-mentioned current collector plate.

[0033] The ratio of the inner diameter of the concentric edge of the can connection to the diameter of the battery cell may be 40 / 46 or less.

[0034] The can connection portion may be joined to the can or side wall member by welding, brazing or soldering.

[0035] The method of joining between the above can connecting portion and the can or side wall member can correspond to the method of joining between the can and the side wall member.

[0036] The above can connection portion may include an axial extension portion extending axially from the centrifugal end.

[0037] The above can connection portion may include a radial extension portion extending in a radial direction.

[0038] The above axial extension portion can be connected to the above radial extension portion through a bending portion.

[0039] The above-mentioned bending portion can bend the radial extension portion extending in the centrifugal direction outward in the axial direction.

[0040] The axial extension of the above can connection portion can extend axially outward from the above bend portion.

[0041] The above can connection part may have a mating outer surface defined by the outer surface of the can connection part.

[0042] The above outer surface of the mating member can be defined by the outer surface of the axial extension.

[0043] The above-mentioned outer surface may face the inner surface of the side wall member in a radial direction.

[0044] The above can connection portion may have a cap mating surface defined by an axial outer end surface.

[0045] The above cap mating surface can be defined by the end face of the axial extension portion.

[0046] The above cap mating surface can be in contact with the inner surface of the cap in the axial direction.

[0047] Accordingly, an axial distance between the radial extension of the can connection portion and the connection portion between the cap and the side wall member can be secured by the axial length of the axial extension portion. In this section, the axial extension portion covers the inner surface of the side wall member. This further reduces the area of ​​the inner surface of the side wall member directly exposed to flame.

[0048] In addition, accordingly, the radial extension portion can be arranged close to the electrode assembly, so that a section of the side wall member provided axially inwardly of the radial extension portion of the current collector plate is arranged farther from the outside air, thereby preventing flames from reaching the section.

[0049] The above cap may include a bonding outer surface facing the inner surface of the side wall member in a radial direction.

[0050] The above-mentioned outer surface of the joint can be in contact with the inner surface of the side wall member in a radial direction.

[0051] The above cap may have a collector plate mating surface defined by an axial inner surface.

[0052] The abutting surface of the above-mentioned collector plate can be in contact with the cap abutting surface of the can connection part of the above-mentioned collector plate in the axial direction.

[0053] The outer surface of the above cap may be positioned axially outside the contact surface of the collector plate.

[0054] The outer surface of the above cap may be positioned radially outward from the contact surface of the collector plate.

[0055] At least a portion of the inner surface of the side wall member and at least a portion of the outer surface of the current collector plate can be joined.

[0056] At least a portion of the inner surface of the side wall member and at least a portion of the joint outer surface of the cap can be joined. Preferably, the joint outer surface of the cap can be entirely joined to the inner surface of the side wall member.

[0057] At least a portion of the cap mating surface of the above collector plate and at least a portion of the collector plate mating surface of the cap can be joined.

[0058] The above joint can be made by welding.

[0059] The above side wall member, the cap and the collector plate can be triple-welded together.

[0060] The above triple welding can be performed by welding together at least a portion of the side wall member, at least a portion of the cap, and at least a portion of the can connection portion of the current collector plate.

[0061] The above welding can be performed by a laser irradiating the abutting portion of the inner surface of the side wall member and the outer surface of the cap in the axial direction.

[0062] At least a portion of the inner surface of the side wall member, at least a portion of the joint outer surface of the cap, and at least a portion of the can connection portion of the current collector plate can be welded together and joined.

[0063] The above battery cell may include a welded portion in which the inner surface of the side wall member, the outer surface of the cap, and the can connection portion of the current collector plate are welded together.

[0064] The outer surface of the joint of the above cap and the outer surface of the mating portion of the above can may each face or contact the inner surface of the side wall member in a radial direction.

[0065] The axial ends of the outer surface of the cap and the inner surface of the side wall member, which are radially facing or abutting each other, can be exposed axially outward.

[0066] The above welded portion can be formed by a laser radiating axially toward the axial ends of the outer surface of the cap and the inner surface of the side wall member from the axial outer side of the battery cell.

[0067] The above cap may be provided with a cap body, a thickness reduction portion, and a joint portion in that order from the radial center outward.

[0068] In other words, the thickness reduction portion may be provided on the centrifugal side of the cap body, and the joint portion may be provided on the centrifugal side of the thickness reduction portion.

[0069] The outer surface of the joint of the above cap can be provided at the joint.

[0070] The first thickness of the above joint may be smaller than the second thickness of the cap body.

[0071] By increasing the second thickness of the cap body, which occupies the overall shape of the cap, the deformation of the cap due to the internal pressure of the can is minimized, while the axial dimension of the welding portion for the side wall member, i.e. the outer circumferential surface of the joint, is suppressed so that the welding portion is formed over the entire axial direction of the outer circumferential surface of the joint, thereby increasing both the strength of the cap itself and the bonding strength of the cap to the side wall member.

[0072] A break inducing portion may be provided on the cap body having the second thickness. Accordingly, when the internal pressure of the battery can increases, deformation is concentrated on the break inducing portion, allowing breakage to occur smoothly.

[0073] According to the present invention, the diameter of the breakage inducing portion provided on the cap can be secured to be large, and thus the radial length of the centrifugal portion of the breakage inducing portion that remains attached to the can after breakage can be shortened. Accordingly, a wider exhaust area can be secured when gases and flames generated during thermal runaway are discharged, and the bottleneck phenomenon caused by the remaining portion of the cap can be minimized. Consequently, side wall breakage can be prevented.

[0074] According to the present invention, since the inner diameter of the can connection portion of the current collector plate provided at the bottom of the can is smaller than the diameter of the damage inducing portion, the phenomenon of gas and flame generated during thermal runaway directly contacting the side wall member existing between the can and the current collector plate can be minimized. Accordingly, damage to the side wall portion of the can can be prevented.

[0075] According to the present invention, since the axial extension of the can connecting portion is joined in a form that overlaps the inner surface of the side wall member, the side wall member at that portion can be reinforced, thereby preventing damage to the side wall portion.

[0076] According to the present invention, the radial extension of the can connection can be arranged closer to the electrode assembly by the axial extension of the can connection, thereby minimizing the phenomenon of gas and flame directly contacting or reaching the side wall member located axially inward of the radial extension. Accordingly, damage to the side wall can be prevented.

[0077] According to the present invention, it is possible to secure weldability (weldability) that allows the side wall member, the cap, and the collector plate to be joined together (welded).

[0078] According to the present invention, process stability can be secured for joining (welding) the side wall member, the cap, and the collector plate together.

[0079] According to the present invention, the assembly work of a battery cell can be significantly reduced by joining the side wall member, the cap, and the collector plate together.

[0080] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0081] Figure 1 is a perspective view of a cylindrical battery cell of an embodiment.

[0082] Figure 2 is an exploded perspective view of the electrode assembly accommodated inside the can of Figure 1 before winding.

[0083] Fig. 3 is a perspective view of the electrode assembly of Fig. 2 in a pre-winding laminated state.

[0084] Fig. 4 is a perspective view of an assembled cylindrical jelly-roll-shaped electrode assembly by winding up the laminate of Fig. 3.

[0085] Figure 5 is a perspective view showing a state in which a first collector plate is joined to an electrode tab of a first electrode of an electrode assembly.

[0086] Figure 6 is a perspective view showing a state in which a second collector plate is joined to an electrode tab of a second electrode of an electrode assembly.

[0087] Figure 7 is a perspective view of the second collector plate of Figure 6.

[0088] Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7.

[0089] Figure 9 is a cross-sectional view taken along line 9-9 of Figure 7.

[0090] Fig. 10 is a perspective view showing a portion of the cross-section of Fig. 8.

[0091] Figure 11 is a side cross-sectional view showing the process of accommodating an electrode assembly with a current collector plate bonded thereto inside a can.

[0092] Figure 12 is a side cross-sectional view showing the bonding process of the first collector plate and the first electrode terminal of the electrode assembly accommodated in the can.

[0093] Figure 13 is a side cross-sectional view showing the process of covering the open end of the can containing the electrode assembly with a cap.

[0094] Figures 14 and 15 are side cross-sectional views showing the process of closing the filling port of a cap that is joined to the side wall member of the can and has its open end closed with a stopper.

[0095] Figures 16 and 17 are upper and lower perspective views of the cap of the embodiment.

[0096] Fig. 18 is a cross-sectional view showing an enlarged area of ​​the open end portion of the battery cell of Fig. 15, where a dashed line is indicated.

[0097] Fig. 19 is a cross-sectional view of a battery cell viewed from a different position from the circumferential direction of Fig. 18.

[0098] Figure 20 is a drawing showing a venting state in which the breakage inducing part of the cap of Figure 19 is broken.

[0099] A battery pack having the battery cells of the embodiments of FIG. 21 and FIG. 222 applied thereto, and a vehicle equipped with such a battery pack are illustrated.

[0100] Figure 23 is a cross-sectional view of the fixing structure of a cap with a beading portion and a crimping portion applied.

[0101] Figure 24 is a drawing showing a venting state in which the breakage inducing part of the cap of Figure 23 is broken.

[0102] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0103] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0104] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0105] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0106] Additionally, when it is described that a component is "connected," "coupled," or "in contact with" another component, it should be understood that the components may be directly connected or in contact with each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "in contact with" another component.

[0107] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0108] Throughout the specification, when we refer to "A and / or B", this means A, B, or A and B, unless otherwise stated, and when we refer to "C through D", this means C or more and D or less, unless otherwise stated.

[0109] In describing the embodiment, the axial direction refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the radial direction refers to the direction approaching (centripetal) or moving away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

[0110] In addition, the loop shape refers to a ring shape having a noose or circle shape, the centrifugal side refers to a direction away from an axis forming the winding center of a jelly-roll-shaped electrode assembly, and the centripetal side refers to a direction approaching an axis forming the winding center of a jelly-roll-shaped electrode assembly.

[0111] Hereinafter, with reference to FIGS. 1 to 20, an embodiment of a battery cell having a side wall member damage prevention structure of the present invention will be described in detail.

[0112] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the ratio of the diameter (Φ) to the height (H) of a cylindrical battery cell) of greater than about 0.4.

[0113] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two numbers indicate the diameter of the cell, the next two numbers indicate the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

[0114] The above battery cell may be a cylindrical battery cell having a roughly cylindrical shape, a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0115] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0116] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0117] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0118] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0119] The present invention can of course also be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. For 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0120] The battery cell of the embodiment includes an electrode assembly (20), a current collector (31, 32) electrically connected to the electrode assembly (20), and a can (10) that accommodates the electrode assembly (20) and the current collector (31, 32).

[0121] The above can (10) includes a bottom member (12), a side wall member (11) connected to the bottom member (12) and extending in the axial direction, and an open end provided at one axial end of the side wall member (11).

[0122] The above can (10) includes a cap (16) covering the open end.

[0123] The above-mentioned floor member (12) has a disc shape with a hole formed in the center, and the side wall member (11) may have a circular tube shape.

[0124] The above-mentioned bottom member (12) and side wall member (11) can be manufactured by forming a metal sheet with a nickel plated surface using a deep drawing process, and trimming the front end of the side wall member (11) with a punch while holding it with a blank holder. Of course, the material of the can (10) is not limited to this.

[0125] A first electrode terminal (13) can be fitted into the hole. The first electrode terminal (13) can be fixed by riveting to the bottom member (12) with a gasket (14) interposed therebetween. The gasket (14) is interposed between the first electrode terminal (13) and the bottom member (12), sealing the inside and outside of the can (10) to prevent leakage of the electrolyte, and electrically insulating the first electrode terminal (13) and the bottom member (12).

[0126] However, the method of connecting the first electrode terminal (13) and the floor member (12) is not limited to this. For example, if the structure can seal the space between the first electrode terminal (13) and the floor member (12) and electrically insulate the first electrode terminal (13) and the floor member (12), various other methods can also be applied.

[0127] The first electrode terminal (13) above may have a first polarity, and the can (10) may have a second polarity. That is, the bottom member (12) of the can (10), the side wall member (11) connected thereto, and the cap (16) connected to the side wall member (11), which will be described later, may all have a second polarity.

[0128] Accordingly, the battery cell may have both the first electrode terminal (13) and the second electrode terminal (15) disposed at the axial end, i.e., the closed end, provided with the bottom member (12), as illustrated in FIG. 1. Then, the battery cell may have both the bus bar connected to the first electrode terminal (13) and the bus bar connected to the second electrode terminal (15) positioned at the upper portion of the battery cell. In one example, the first electrode terminal (13) may be a positive terminal, and the second electrode terminal (15) may be a negative terminal. Of course, the opposite may also be the case.

[0129] An electrode assembly (20) is accommodated within the can (10). The electrode assembly (20) is manufactured in the form of a jelly-roll by preparing a first electrode (21), a second electrode (22), and a separator (28) having a predetermined width and extending in the longitudinal direction as illustrated in FIG. 2, and then forming a laminate by sequentially stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28) as illustrated in FIG. 3, and then winding this around a core shaft as illustrated in FIG. 4. The first electrode (21) may be a positive electrode, and the second electrode (22) may be a negative electrode. Of course, the opposite may also be the case.

[0130] The above first electrode (21) and second electrode (22) are manufactured in the form of sheets. The electrode sheet is manufactured in the form of an active material layer (24) applied to the surface of a metal foil (23). The electrode sheet has a holding portion (25) region where the active material layer (24) is applied, and a non-coated portion (26) region where the active material layer (24) is not applied. The positive electrode sheet has a non-coated portion (26) region on one side in the width direction, and the negative electrode sheet has a non-coated portion (26) region on the other side in the width direction.

[0131] The non-conductive portion (26) is exposed or protrudes in the width direction of the laminate. The non-conductive portion (26) itself functions as an electrode tab (27).

[0132] In the above-mentioned blank portion (26), notches can be formed at a predetermined interval to form flag-shaped notching tabs (27).

[0133] In the embodiment, the notching tabs (27) are exemplified as having an equilateral trapezoidal shape. However, their shapes may be various, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0134] In addition, in the embodiment, a form in which the notching tabs (27) arranged along the longitudinal direction have the same width is exemplified. However, the width of the notching tabs may be gradually or stepwise widened from the core side to the outer periphery side.

[0135] In addition, in the embodiment, a form in which the height of the notching tabs (27) gradually increases from the core side to the outer circumference side is exemplified. However, the height of these notching tabs may be implemented in a form in which they are constant or gradually decrease.

[0136] In addition, in the embodiment, a structure is exemplified in which a notching tab (27) is deleted in a predetermined section of the centrifugal end of the non-conductive portion (26) and a predetermined section of the centrifugal end. However, it is of course possible that the notching tab may not be deleted in the centrifugal end of the non-conductive portion, and that the notching tab may not be deleted in the centrifugal end of the non-conductive portion.

[0137] In the jelly roll-shaped electrode assembly (20), the notched tab (27) can be bent radially and flattened as shown in FIG. 4. The notched tab (27) can be bent radially or outwardly. In the embodiment, a structure in which the notched tab (27) is bent radially is exemplified.

[0138] The above-mentioned notched tabs (27) can be bent one by one during the process of forming a jelly roll-shaped electrode assembly (20) by winding the laminate. Alternatively, the above-mentioned notched tabs (27) can be bent all at once after the laminate is wound to form a jelly roll-shaped electrode assembly.

[0139] The notched tabs (27) of the first electrode (21) and the notched tabs (27) of the second electrode (22), which are folded and overlapped in a radial direction, can provide a plane that is substantially perpendicular to the axial direction at each of the axial ends of the electrode assembly (20).

[0140] As shown in FIGS. 5 and 6, the first collector plate (31) and the second collector plate (32) can be joined to a substantially flat surface provided by bending the notched tabs (27) exposed at both axial ends of the electrode assembly (20).

[0141] In the embodiment, the first collector plate (31) is exemplified as a positive collector plate and the second collector plate (32) is exemplified as a negative collector plate. The first collector plate (31) may be made of aluminum, and the second collector plate (32) may be made of copper.

[0142] The above-mentioned collector plate (31, 32) can be manufactured by punching, trimming, piercing, and bending a metal sheet.

[0143] Referring to Fig. 5, the first collector plate (31) has a terminal connection portion (312) extending radially from the center, a ring portion (313) connecting the centrifugal edge of the terminal connection portion (312) in a circumferential direction, and an electrode connection portion (314) extending centripetally from the ring portion (313) but not connected to the terminal connection portion (312). The center portion of the terminal connection portion (312) covers at least a portion of the core hollow portion of the electrode assembly (20).

[0144] The above electrode connection part (314) is joined to the notched tab (27) of the first electrode (21) of the electrode assembly (20) by laser welding or the like before the electrode assembly (20) is placed in the can (10). The welding line of the laser may extend radially.

[0145] Referring to FIGS. 6 to 9, the second collector plate (32) includes a main body portion (320) connected to the electrode tab (27) of the electrode assembly (20) and an outer ring-shaped can connection portion (324) disposed on a more distal side than the main body portion (320) and surrounding the edge of the second collector plate (32). The loop-shaped can connection portion (324) is disposed radially apart from the main body portion (320).

[0146] The second collector plate (32) includes a bridge (33) whose centripetal side is connected to the main body (320) and whose centrifugal side is connected to the can connection part (324).

[0147] The main body (320) includes an inner ring (321) that defines a hole (322) corresponding to the core hollow portion of the electrode assembly (20) and is provided in a form that surrounds the core hollow portion, and an electrode tab connection portion (323) that extends radially from the inner ring portion (321). The main body (320) can be electrically connected to the electrode tab (27) of the electrode assembly (20) by welding with a laser irradiated onto the electrode tab connection portion (323).

[0148] The above electrode tab connection portion (323) can be joined to the notched tab (27) of the second electrode (22) of the electrode assembly (20) by laser welding or the like before placing the electrode assembly (20) into the can (10). The welding line of the laser can extend radially.

[0149] The above can connection part (324) is electrically connected to the main body part (320) through the bridge (33) extending in a radial direction.

[0150] The above can connection part (324) has a radial extension part (3242) extending in a radial direction, a bend part (327) provided at the centrifugal end of the radial extension part (3242), and an axial extension part (3241) extending axially outward from the bend part (327).

[0151] The above bridge (33) can be arranged alternately with the electrode tab connection portion (323) in the circumferential direction. The above bridge (33) can be connected to the inner ring portion (321).

[0152] As illustrated in FIGS. 11 and 12, the electrode assembly (20) is accommodated in the can (10) in a state where the first collector plate (31) is aligned toward the bottom member (12) of the can (10). At this time, an insulator (19) is interposed between the first collector plate (31) and the bottom member (12) of the can (10) to electrically insulate the first collector plate (31) and the bottom member (12).

[0153] And, the terminal connection part (312) of the first collector plate (31) is joined to the first electrode terminal (13) fixed to the can (10) by resistance welding, ultrasonic welding, laser welding, or the like. The welding device for welding the first collector plate (31) and the first electrode terminal (13) can approach the back surface of the center of the terminal connection part (312) of the first collector plate (31) through the core hollow part of the electrode assembly (20) from the open end of the can (10) and perform welding. Of course, in addition to this, the first collector plate (31) and the first electrode terminal (13) can also be joined by brazing or soldering. In other words, various methods can be applied to the first collector plate (31) and the first electrode terminal (13) as long as they are a joining method that can electrically connect them and fix them to each other.

[0154] With the electrode assembly (20) housed inside the can (10), the electrode tab (27) of the second electrode (22) and the second collector plate (32) are positioned to face the open end of the side wall member (11). In addition, the outer circumferential surface of the second collector plate (32) is in contact with the inner circumferential surface of the side wall member (11) and is pressed into it.

[0155] After the first collector plate (31) and the first electrode terminal (13) are joined, the open end of the side wall member (11) is covered by a cap (16) as shown in FIGS. 13 and 14 and finished through seam welding or the like. Then, an electrolyte can be injected into the can (10) through the injection port (18) provided in the center of the cap (16).

[0156] After injecting the electrolyte, as shown in FIGS. 14 and 15, the injection port (18) can be closed by a stopper (40).

[0157] Of course, the welding structure of the present invention can also be applied to a cap without a liquid injection port. Accordingly, before covering the open end of the side wall member (11) with the cap (16), the electrolyte can be injected first, and after the electrolyte injection is complete, the open end can be covered with the cap (16) for final closure.

[0158] The edge of the cap (16) is joined by laser welding with the edge of the side wall member (11) as shown in Fig. 18, and thus the can (10) can be sealed.

[0159] The can connection portion (324) provided at the edge of the second collector plate (32) and electrically connected to the can (10) includes a first portion that faces or comes into contact with the inner surface of the side wall member (11). The first portion is provided with a mating outer surface (325) that faces or comes into contact with the inner surface of the side wall member (11) in a radial direction.

[0160] The above can connection portion (324) includes a second portion that comes into contact with the cap (16). The second portion is provided with a cap mating surface (326) that faces and comes into contact with the inner surface of the cap (16) in the axial direction.

[0161] The above first and second parts are provided in the axial extension (3241) of the can connection part (324).

[0162] The axial extension (3241) of the above can connection (324) is connected to the axial outer side of the above bending portion (327) and has a shape extending axially outward from the above bending portion (327). Accordingly, the area and axial length of the mating outer surface (325) of the second collector plate (32) can be further secured.

[0163] The material of the above second collector plate (32) may be softer than the material of the side wall member (11).

[0164] The thermal conductivity of the above second collector plate (32) may be higher than the thermal conductivity of the side wall member (11).

[0165] For example, the material of the second collector plate (32) may include copper, and the material of the side wall member (11) may include iron.

[0166] The outer diameter of the mating outer surface (325) of the above can connection portion (324) is set to correspond to or be larger than the inner diameter of the inner surface of at least a portion of the axial direction of the side wall member (11).

[0167] Then, in the process of inserting the second collector plate (32), the bending portion (327) is elastically deformed and the outer surface of the mating member (325) is forcibly pressed into the inner surface of the side wall member (11) and adhered in a radial direction.

[0168] The radial extension (3242) of the can connection portion (324) supports the outer shape of the can connection portion (324) when the bend portion (327) is elastically deformed by applying a force toward the center.

[0169] The above-mentioned bending portion (327) provides a curved surface whose outer diameter gradually decreases as it goes axially inward compared to the outer diameter of the axial extension portion (3241) of the can connection portion (324). Accordingly, in the process of inserting the second collector plate (32) into the inner space of the side wall member (11), the can connection portion (324) can be guided to be forcibly pressed into the inner surface of the side wall member (11).

[0170] Referring to FIGS. 16 to 20, the cap (16) is provided with a cap body (160), a thickness reduction portion (161), and a joint portion (17) in that order from the radial center outward. That is, the thickness reduction portion (161) is provided on the centrifugal side of the cap body (160), and the joint portion (17) is provided on the centrifugal side of the thickness reduction portion (161).

[0171] At the joint portion (17) of the cap (16), a joint outer surface (171) is provided that faces or comes into contact with the inner surface of the side wall member (11) in a radial direction. In addition, at the axial inner surface of the joint portion (17) of the cap (16), a collector plate mating surface (173) that faces and comes into contact with the cap mating surface (326) of the can connection portion (324) of the second collector plate (32) in the axial direction is provided.

[0172] The above thickness reduction portion (161) is a thickness change portion provided in the cap (16).

[0173] By appropriately selecting the position where the thickness reduction portion (161) is provided so that at least a portion of the thickness reduction portion (161) can contact the second collector plate (32), the thickness reduction portion (161) of the cap (16) comes into contact with the second collector plate (32) during the process of inserting the cap (16), and the effect of aligning the center of the cap (16) can be enjoyed. In order to enhance the alignment effect, the embodiment implemented the thickness reduction portion (161) in the form of an inclined surface that extends axially outward as it goes toward the centrifugal side.

[0174] In the process of inserting the cap (16) into the side wall member (11), the thickness reduction portion (161) in the form of an inclined surface can come into contact with the centripetal edge of the cap abutment surface (326). Accordingly, the axial outer end of the can connection portion (324) of the second collector plate (32) provided with the cap abutment surface (326) is pressed toward the centrifugal side by the thickness reduction portion (161), so that it can be arranged closer to or in closer contact with the inner surface of the side wall member (11).

[0175] And, in the axial direction, the cap mating surface (326) provided on the axial outer end surface of the can connection portion (324) of the second collector plate (32) is in contact with the collector plate mating surface (173) provided on the inner surface of the joint portion (17) of the cap (16). According to this assembly structure, the insertion depth of the cap (16) can be precisely regulated by the height of the second collector plate (32), which can be determined by the axial extension length of the can connection portion (324).

[0176] In the above battery cell, a welded portion (W) is formed in which the inner peripheral surface of the side wall member (11), the joint outer peripheral surface (171) of the cap (16), and the axial extension (3241) of the can connection portion (324) of the second collector plate (32) are welded together at the abutting portion between the side wall member (11), the cap (16), and the second collector plate (32).

[0177] As shown, the axial end of the joint outer surface (171) of the cap (16) and the inner surface of the side wall member (11), which are radially opposed to each other, are exposed to the axial outer side.

[0178] The above welding part (W) is formed by a laser irradiating the axial end of the second inner surface (115) of the side wall member (11) and the joint outer surface (171) of the cap (16) from the axial outer side of the battery cell.

[0179] The above welding portion (W) includes a portion where at least a portion of the inner surface of the side wall member (11) and at least a portion of the mating outer surface (325) of the collector plate (32) are joined, a portion where at least a portion of the inner surface of the side wall member (11) and at least a portion of the mating outer surface (171) of the cap (16) are joined, and a portion where at least a portion of the cap mating surface (326) of the collector plate (32) and at least a portion of the mating surface (173) of the cap (16) are joined. Preferably, the mating outer surface (171) of the cap (16) can be entirely welded. That is, the above welding portion (W) can be formed by triple welding.

[0180] The abutting portion of the side wall member (11) and the cap (16) is heated to a high temperature by a laser (L) that is irradiated to form the above welding portion (W).

[0181] Then, the heat generated in the side wall member (11) by the laser can be quickly dispersed and conducted through the second collector plate (32) having a wider contact area, and the heat generated in the cap (16) by the laser can be somewhat more slowly dispersed and conducted through the second collector plate (32) having a narrower contact area. Accordingly, the melting point of the side wall member (11), which is relatively thinner than the joint (17) of the cap (16), can be further delayed.

[0182] In addition, since most of the welding heat transmitted through the side wall member (11) is distributed through the second collector plate (32), the phenomenon of heat being transmitted toward the separator (28) of the electrode assembly (20) in contact with the inner surface of the side wall member (11) can be further reduced.

[0183] Meanwhile, as previously described, in the cap (16), the first thickness of the joint (17) is smaller than the second thickness of the cap body (160) measured in the axial direction. Accordingly, the depth at which the cap (16) must be welded to the side wall member (11) is determined by the first thickness, and the resistance to the bulging phenomenon of the cap (16) caused by an increase in internal pressure of the can (10) due to thermal runaway of the battery cell, etc., is determined by the second thickness.

[0184] According to the present invention, even if welding is performed between the cap (16) and the side wall member (11) to a depth of the first thickness, the abutting portion of the cap (16) and the side wall member (11) is completely bonded and connected, so that no portion where stress is concentrated occurs when bulging occurs, and the cap body (160) is made of a thicker second thickness, so that it can have greater bulging resistance.

[0185] In addition, according to the present invention, since the thickness reduction portion (161) of the cap (16) for interaction with the can connection portion (324) during the assembly process is positioned centripetally from the joint outer circumferential surface (171) only to an extent corresponding to the radial thickness of the can connection portion (324), the area of ​​the cap body (160) of the second thickness can be secured more widely, thereby further increasing the bulging resistance. Since a current collector plate such as the second current collector plate (32) is typically manufactured by a molding process that presses a thin metal sheet, it will be understood that the thickness reduction portion (161) can be positioned very close to the radial edge of the cap (16).

[0186] The cap (16) is provided with a loop-shaped breakage inducing portion (165) that is substantially concentric with the edge of the cap (16). The breakage inducing portion (165) may be defined as a portion having a thin thickness by forming a notch on each of the front and back surfaces of the cap (16).

[0187] The above-mentioned breakage inducing member (165) may be arranged adjacent to the edge of the cap (16). According to an embodiment, the side wall member (11) is extended in the axial direction, and the axial end of the side wall member (11) is also joined to the edge of the cap (16) by welding or the like without being bent toward the center, so that the joint portion of the can (10) and the cap (16) takes up almost no space in the radial direction. Accordingly, it is possible for the breakage inducing member (165) to be arranged adjacent to the edge of the cap (16).

[0188] As the diameter of the above-mentioned breakage inducing portion (165) increases, the area occupied in the radial direction by the cap (16) portion (C) that remains connected to the can (10) in a state where the breakage inducing portion (165) is broken due to thermal runaway as illustrated in FIG. 19 can be reduced. This can minimize or eliminate the bottleneck phenomenon in which gas and flame are not immediately discharged when they are discharged but remain in the internal space of the can.

[0189] Accordingly, it is possible to prevent the flame from directly contacting the side wall member (11), thereby preventing side wall rupture from occurring, and when a thermal runaway occurs in one battery cell in a battery pack or the like, causing venting of gas and flame, it is possible to prevent other cylindrical battery cells positioned side by side from being affected.

[0190] The ratio of the diameter of the above-mentioned breakage inducing portion (165) to the diameter of the above-mentioned can (10) may be 38 / 46 or more. Of course, it is obvious that the above-mentioned ratio is naturally less than 1.

[0191] Preferably, the diameter ratio may be 40 / 46 or more. As a result of the experiment, in a structure where the edge of the cap (16) is connected to the can (10) in a plane perpendicular to the side wall member, when the ratio is 38 / 46 or more, no damage to the side wall member occurred during the venting process. In addition, when the ratio is 40 / 46 or more, it was confirmed that a bottleneck phenomenon did not occur during the venting process, and thus the side wall member did not come into direct contact with the flame.

[0192] The breakage inducing portion (165) of the cap (16) may be positioned radially further outward than the radially inner edge of the can connection portion (324) of the second collector plate (32). When the can connection portion (324) extends further radially than the breakage inducing portion (165) of the cap (16) during venting, gas and flame are actively ejected near the radially inner edge of the can connection portion (324), making it difficult for external oxygen to flow into the space located axially inner than the can connection portion (324). Accordingly, the phenomenon of flames directly contacting the side wall member (11) axially inner than the can connection portion (324) can be minimized.

[0193] The ratio of the inner diameter of the radial extension (3242) of the can connection (324) to the diameter of the can (10) may be 42 / 46 or less. Preferably, the ratio may be 40 / 46 or less.

[0194] If the ratio of the inner diameters of the radial extension portion (3242) is 42 / 46 or more, the length of the radial extension portion (3242) cannot be sufficiently secured, so that when the second collector plate (32) is pressed into the inner periphery of the side wall member (11) of the can (10), it is difficult to sufficiently secure a supporting force to support the axial extension portion (3241) toward the centrifugal side with only the radial extension portion (3242), and it is difficult to rule out the possibility that the flame will directly contact the side wall member during thermal runaway.

[0195] The ratio of the inner diameter of the radial extension (3242) of the can connection (324) to the diameter of the can (10) may be 36 / 46 or greater. Preferably, the ratio may be 38 / 46 or greater. If the ratio is less than 36 / 46, there is a possibility that gas and flame ejection may be impeded during the venting process.

[0196] According to the present invention, the distance between the radial extension (3242) of the can connection (324) and the can (10) can be determined by the extension length of the axial extension (3241) of the can connection (324). Accordingly, the axial distance between the radial extension (3242) and the electrode assembly (20) can also be adjusted. As the distance between the radial extension (3242) and the electrode assembly (20) increases, the influence of the welding heat of the can (10) and the cap (16) on the electrode assembly (20) can be reduced, but the possibility that the side wall member (11) located between the axial radial extension (3242) and the electrode assembly (20) will be directly exposed to the flame during the venting process increases.

[0197] According to the present invention, the length of the axial extension portion (3241) is determined within a range in which the welding heat of the can (10) and the cap (16) does not affect the electrode assembly (20), and the side wall member (11) portion located axially inside the radial extension portion (3242) is not exposed to the flame during the venting process, so that the welding heat does not affect the electrode assembly (20), and the side wall member (11) is not exposed to the flame during the venting process.

[0198] Meanwhile, in the section between the radial extension (3242) and the can (10), the axial extension (3241) is joined to the side wall member (11) of the can (10), so that the can connection member (324) can prevent the flame from directly contacting the side wall member (11).

[0199] A battery cell (72) having the assembly structure of the second collector plate, cap, and can described above can be accommodated in a housing (71) of a battery pack (70) as illustrated in Fig. 21. The battery pack (70) may be configured using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be configured directly without a battery module as illustrated.

[0200] Since the battery cell (72) described above has a large volume in itself, there is no particular difficulty in implementing a battery pack (70) even without using an intermediate structure called a battery module. Furthermore, the battery cell (72) has low internal resistance and a higher energy density. Accordingly, the energy density of a battery pack (70) equipped with the battery cell (72) can be implemented even higher.

[0201] According to the present invention, the energy density of the battery cell (72) can be sufficiently secured, and even if thermal runaway occurs due to abnormal operation of the battery cell, the sidewalls are not damaged, thereby preventing the thermal runaway from spreading to surrounding battery cells. Accordingly, even if the battery cells are configured as modules and then directly configured as a pack, the phenomenon of thermal runaway spreading throughout the entire battery pack can be prevented.

[0202] This battery pack (70), which enhances safety while also increasing energy density, can store the same amount of energy while reducing its volume and weight. Therefore, when a battery pack (70) equipped with such battery cells (72) is installed in a vehicle, such as an automobile (80) that uses electricity as its energy source, as illustrated in FIG. 22, the vehicle's mileage per unit of energy consumed can be further increased.

[0203] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow, rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all possible modifications and variations derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0204] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

[0205] [Explanation of symbols]

[0206] 10: Can

[0207] 11: Side wall member

[0208] 117: Bidding Department

[0209] 118: Crimping section

[0210] 12: Flooring

[0211] 13: First electrode terminal (positive terminal)

[0212] 14: Gasket

[0213] 15: Second electrode terminal

[0214] 16: Cap

[0215] 160: Cap body

[0216] 161: Thickness reduction section

[0217] 165: Breakage induction section

[0218] 169: Gasket

[0219] 17: Joint

[0220] 171: Joint outer circumference

[0221] 173: The collector plate is facing each other

[0222] 18: Injection hole

[0223] 19: Insulator

[0224] 20: Electrode assembly

[0225] 21: First electrode

[0226] 22: Second electrode

[0227] 23: Metal foil

[0228] 24: Active material layer

[0229] 25: Maintenance Department

[0230] 26: Ministry of Immigration

[0231] 27: Electrode tab (notching tab)

[0232] 28: Membrane

[0233] 31: First collector plate (positive collector plate)

[0234] 312: Terminal connection

[0235] 313: Ringbu

[0236] 314: Electrode connection

[0237] 32: Second collector plate (negative collector plate)

[0238] 320: Main body

[0239] 321: Inner ring

[0240] 322: Hall

[0241] 323: Electrode tab connection

[0242] 324: Can connector

[0243] 3241: Axial extension

[0244] 3242: Radial extension

[0245] 325: Matching outer circumference

[0246] 326: If the cap is aligned

[0247] 327: Bend

[0248] 33: Bridge

[0249] 40: Stopper

[0250] W: Welding

[0251] 70: Battery pack

[0252] 71: Housing

[0253] 72: Battery cell

[0254] 80: Vehicle

Claims

1. A battery cell including a can including a side wall member extending in the axial direction; and an open end provided at one axial end of the side wall member; a cap covering the open end; an electrode assembly accommodated inside the can; and a current collector electrically connecting the electrode assembly and the can. The edge of the above cap is joined to one axial end of the above side wall member, The above cap is provided with a loop-shaped breakage inducing portion concentric with the edge of the cap, The above collector plate: A main body part connected to the electrode tab of the above electrode assembly; A loop-shaped can connecting portion positioned on the centrifugal side relative to the main body and joined to at least one of the side wall member and the cap; and A bridge is included, the centripetal side being connected to the main body part, the centrifugal side being connected to the can connection part, and extending radially; The breakage inducing portion of the above cap is a battery cell positioned radially further outward than the centric edge of the above can connection portion.

2. In claim 1, A battery cell characterized in that the cap and side wall members are joined by welding, brazing or soldering.

3. In claim 1, A battery cell, characterized in that the ratio of the diameter of the breakage inducing portion to the diameter of the battery cell is 38 / 46 or more.

4. In claim 1, A battery cell characterized in that the can connection part is joined to the can or the side wall member by welding, brazing or soldering.

5. In claim 1, A battery cell characterized in that the method of joining the can connecting portion and the can or side wall member corresponds to the method of joining the cap and the side wall member.

6. In claim 1, A battery cell, characterized in that the ratio of the inner diameter of the center edge of the can connection to the diameter of the battery cell is 40 / 46 or less.

7. In claim 1, The above can connection part: Radial extension extending in a radial direction; An axial extension portion extending axially from the centrifugal end of the above radial extension portion; An outer surface defined by the outer surface of the axial extension and facing and in contact with the inner surface of the side wall member; and A battery cell characterized by including a cap mating surface defined by an axial outer end surface of the axial extension portion and facing and contacting the inner surface of the cap in the axial direction.

8. In claim 7, A battery cell characterized in that the cap includes a collector plate mating surface defined by an axial inner surface and axially facing and contacting a cap mating surface of a can connection portion of the collector plate.

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