Battery cell and kit for assembling battery cell

Abstract

The utility model provides a battery cell and a kit for assembling the battery cell. A battery cell includes a collector plate having an axially extending can connection portion press-fitted within a side wall member having a plurality of stages of inner peripheral surfaces having different inner diameters. A battery cell is manufactured by inserting a cap into an open end of a can such that an axially inner surface of the cap contacts an axially outward end surface of a can connection portion and such that an outer peripheral surface of the cap contacts an inner peripheral surface of a side wall member. Then, laser light is irradiated in the axial direction on a region where the inner peripheral surface of the side wall member and the outer peripheral surface of the cap are in contact with each other, so as to form a triple welded portion.

Description

Technical Field

[0001] The present disclosure relates to the field of batteries, and in particular to a welding structure of a battery can, a current collecting plate and a cap, and to a battery cell using the welding structure. Background Art

[0002] The manufacturing process of the cylindrical cell battery may include deep drawing a metal plate to form a can having a circular bottom and a tubular side wall member connected to the circular bottom, then accommodating the electrode assembly in the can, and then covering the open end of the side wall member with a cap. At the same time, a current collector that contacts and is electrically connected to at least one electrode connector of the electrode assembly is provided at one of the two axial ends of the electrode assembly (i.e., the axial end facing the open end). The current collector is in contact with and electrically connected to the cap or the side wall member by a method of welding the current collector to the cap or the side wall member.

[0003] The process of connecting the current collecting plate to the cap or the sidewall member (e.g., by welding) and connecting the cap to the sidewall member is performed separately for each battery cell. The labor-intensive and time-consuming process of connecting these components separately reduces production efficiency and increases the production cost of manufacturing cylindrical battery cells.

[0004] In order to avoid such a separate welding process, it is possible to consider welding the side wall member, the cap, and the current collecting plate at one time, which can be performed by laser. However, in a large-scale production process, it is difficult to quickly assemble the three components (e.g., the side wall member, the cap, and the current collecting plate) and firmly fix them together to achieve a strong weld.

[0005] In addition, when the side wall member is irradiated with laser, the cap and the current collecting plate may be assembled roughly, and a gap may exist due to the tolerance of each component of the side wall member, the cap and the current collecting plate, which is caused by the assembly error. When assembling with laser irradiation in the presence of such a gap, the laser may directly penetrate into the can, thereby causing damage to the electrode assembly contained in the can. Therefore, it is desirable to improve the assembly of cylindrical battery cells. Utility Model Content

[0006] The present disclosure provides a welding structure of a battery can, a current collector and a cap, and a battery cell using the welding structure, wherein the process of welding the current collector to the can and the process of welding the cap to the side wall member are integrated into a single welding process, thereby improving the production efficiency of the cylindrical battery cell and reducing the production cost. Additionally or alternatively, even if there are component tolerances and assembly errors in the side wall member, the cap and the current collector, the structure can prevent the laser from directly penetrating into the can during the laser welding process.

[0007] Additionally or alternatively, the assembly of the tank, the collector plate, and the cap can be facilitated. In-place alignment and close contact can be achieved through the mutual contact structure in the assembly process, thereby facilitating triple welding. The shape and / or engagement relationship between the tank, the collector plate, and the cap of the present disclosure can also beneficially improve the effectiveness and / or durability of welding, and / or can improve process stability.

[0008] However, the technical problems solved by the present disclosure are not limited to the above-mentioned purposes, but other purposes and advantages not described in the present disclosure can be understood through the following description and examples. Although a cylindrical cell battery is described herein, aspects of the present disclosure can be applied to other similar battery shapes that are not cylindrical, such as an inclined cylinder or an elliptical cylinder, and other battery form factors, such as a pouch cell battery or a square cell battery.

[0009] Technical Solution

[0010] In order to solve the above-mentioned problems, the present disclosure may be applied to a battery cell including an electrode assembly, a current collecting plate electrically connected to the electrode assembly, and a can receiving or accommodating the electrode assembly and the current collecting plate therein.

[0011] The can includes an axially extending sidewall member and an open end disposed at one (eg, first) axial end of the sidewall member.

[0012] The battery cell includes a cap covering the open end.

[0013] The bottom member is connected to the other axial end of the side wall member (eg, the second end opposite to the first end), so the other axial end of the side wall member can constitute a closed end.

[0014] The electrode assembly may be in the form of a jellyroll type wound around a predetermined axis.

[0015] An electrode tap may be provided at one of both ends of the electrode assembly in the axial direction corresponding to the open end of the can, and the current collecting plate may be electrically connected to the electrode tap.

[0016] The current collecting plate may include an electrode tab connection portion contacting and electrically connected to the electrode tab.

[0017] The electrode joint connection portion may be combined with the electrode joint by welding, brazing or soldering.

[0018] The current collecting plate includes a tank connecting portion that contacts and is electrically connected to the tank.

[0019] The tank connection portion and the electrode tab connection portion may be electrically connected.

[0020] The can connection portion may be disposed radially outside the electrode tab connection portion.

[0021] The tank connecting portion may extend in the axial direction.

[0022] The tank connection portion may be connected to the electrode tab connection portion through a bent portion.

[0023] The bent portion may be a portion of the current collecting plate extending radially outwardly bent outwardly in the axial direction.

[0024] The tank connection portion may extend axially outward from the bent portion.

[0025] The tank connection portion has a peripheral contact surface defined by a periphery of the tank connection portion.

[0026] The outer peripheral contact surface faces the inner peripheral surface of the side wall member in the radial direction.

[0027] At least one section of the outer peripheral contact surface in the axial direction defines a first section in which the outer peripheral contact surface is in contact with the inner peripheral surface of the side wall member in the radial direction.

[0028] The can connection portion is provided with a cap contact surface defined by an axially outer end surface.

[0029] The cap contact surface faces the inner surface of the cap in the axial direction and contacts the inner surface of the cap.

[0030] The cap includes an outer peripheral bonding surface that faces and contacts the inner peripheral surface of the side wall member in a radial direction.

[0031] The outer peripheral bonding surface may be in contact with the inner peripheral surface of the side wall member in the radial direction.

[0032] The cap has a collector plate contact surface defined by an axial inner surface.

[0033] The current collecting plate contact surface faces and contacts a cap contact surface of the can connecting portion of the current collecting plate in the axial direction.

[0034] The outer peripheral engagement surface of the cap may be disposed axially outwardly relative to the current collecting plate contact surface.

[0035] The outer peripheral bonding surface of the cap may be disposed radially outwardly relative to the current collecting plate contact surface.

[0036] At least a portion of an inner peripheral surface of the sidewall member and at least a portion of an outer peripheral contact surface of the current collecting plate may be combined.

[0037] At least a portion of an inner peripheral surface of the side wall member and at least a portion of an outer peripheral bonding surface of the cap may be bonded.

[0038] At least a portion of the cap contact surface of the current collecting plate and at least a portion of the current collecting plate contact surface of the cap may be bonded.

[0039] The bonding may be performed by welding.

[0040] The side wall members, the cap and the collector plate may be triple welded together.

[0041] The welding may be performed by irradiating laser light in the axial direction to a contact area of ​​the inner peripheral surface of the side wall member and the outer peripheral joining surface of the cap.

[0042] At least a portion of an inner peripheral surface of the sidewall member, at least a portion of an outer peripheral bonding surface of the cap, and at least a portion of the tank connection portion of the current collecting plate may be welded together for bonding.

[0043] An outer diameter of at least one section of the outer peripheral contact surface in the axial direction may be larger than an inner diameter of an inner peripheral surface of the side wall member facing the section in the radial direction.

[0044] The outer diameter of the first section of the peripheral contact surface may be greater than the inner diameter of the inner peripheral surface of the side wall member radially facing the first section. Therefore, when the current collecting plate is inserted into the tank, the first section of the peripheral contact surface of the current collecting plate may be forced to be press-fitted into the side wall member.

[0045] The battery cell may include a welding portion in which an inner peripheral surface of the sidewall member, an outer peripheral bonding surface of the cap, and a can connection portion of the current collecting plate are welded together.

[0046] Each of the outer peripheral bonding surface of the cap and the outer peripheral contact surface of the can may face the inner peripheral surface of the sidewall member in the radial direction.

[0047] Each of the outer peripheral bonding surface of the cap and the outer peripheral contact surface of the can may be in contact with the inner peripheral surface of the sidewall member in the radial direction.

[0048] Axial ends of the outer peripheral joint surface of the cap and the inner peripheral surface of the sidewall member, which face or contact each other in the radial direction, may be exposed at the axially outer side of the can.

[0049] The welded portion may be formed by irradiating laser light in the axial direction from the axially outer side of the battery cell toward the axial end portions of the outer peripheral joining surface of the cap and the inner peripheral surface of the side wall member.

[0050] According to the present disclosure, a first section of the outer peripheral contact surface of the current collecting plate disposed axially inside the cap faces and contacts the inner peripheral surface of the side wall member, thereby preventing laser from being directly irradiated into the inner space of the can.

[0051] The current collecting plate may have a higher thermal conductivity than the side wall member. Therefore, welding heat is dispersed to the electrode assembly through the current collecting plate, thereby preventing the welding heat from being transferred to the outer peripheral surface of the electrode assembly through the side wall member to cause damage to the separator disposed on the outer peripheral surface of the electrode assembly.

[0052] An enlarged inner diameter portion may be provided at one axial end of the side wall member.

[0053] An inner diameter of a first inner peripheral surface of the side wall member disposed axially inside the inner diameter expansion portion may be smaller than an inner diameter of a second inner peripheral surface of the side wall member disposed axially outside the inner diameter expansion portion.

[0054] The inner diameter-enlarged portion may have a shape in which the inner diameter of the side wall member increases as the inner diameter-enlarged portion extends toward the axially outer side.

[0055] The expanded inner diameter portion is provided on the inner surface of the side wall member and may include an inclined surface that further extends radially outward as the expanded inner diameter portion extends toward the axially outer side.

[0056] The expanded inner diameter portion may prevent internal penetration of laser light that may enter through a gap between the side wall member and the cap or the current collecting plate.

[0057] At least a portion of a first section of the outer peripheral contact surface in the axial direction may be in contact with the first inner peripheral surface.

[0058] At least a portion of the first section of the outer peripheral contact surface in the axial direction may also be in contact with the expanded inner diameter portion.

[0059] At least a portion of the first section of the outer peripheral contact surface in the axial direction may also be in contact with the second outer peripheral surface.

[0060] The outer diameter of the first section of the outer peripheral contact surface may be greater than the inner diameter of the first inner peripheral surface.

[0061] An outer diameter of an outer peripheral contact surface of the tank connection portion of the current collecting plate may be greater than an inner diameter of the first inner peripheral surface.

[0062] The material of the current collecting plate may be softer than that of the side wall member.

[0063] When the outer diameter of the outer peripheral contact surface is selected to be slightly larger than the inner diameter of the first inner peripheral surface, the outer peripheral contact surface can be pressed on the first inner peripheral surface during the insertion process of the current collecting plate, so that the outer peripheral contact surface and the first inner peripheral surface are in close contact in the radial direction.

[0064] Therefore, in the case where the current collecting plate is inserted, an outer diameter of a first section of the outer peripheral contact surface contacting the first inner peripheral surface may correspond to an inner diameter of the first inner peripheral surface.

[0065] The curved surface may be formed by a bent portion at the axial inner side of the cap connecting portion, and an outer diameter of the curved surface gradually decreases as the curved surface extends toward the axial inner side.

[0066] A minimum outer diameter of the curved surface may be smaller than an inner diameter of the first inner circumferential surface.

[0067] Therefore, in the process of inserting the current collecting plate, forced press-fitting of the cap connecting portion may be applied to the first inner circumferential surface.

[0068] The first inner peripheral surface of the side wall member, into which the first section of the outer peripheral contact surface is forcibly press-fitted, may be positioned closer to the bent portion in the axial direction than the second inner peripheral surface of the side wall member.

[0069] The outer peripheral bonding surface of the cap may face the second inner peripheral surface in a radial direction.

[0070] The outer peripheral contact surface of the tank connecting portion may face the second inner peripheral surface in the radial direction at the axially inner side of the outer peripheral joint surface.

[0071] Each of an outer peripheral bonding surface of the cap and an outer peripheral contact surface of the can connection portion of the current collecting plate may be in contact with the second inner peripheral surface.

[0072] An outer diameter of the outer peripheral contact surface may correspond to or be smaller than an inner diameter of the second inner peripheral surface.

[0073] The cap may include a cap body, a reduced thickness portion, and a coupling portion in sequence from the center toward the radial outer side of the cap.

[0074] In other words, the reduced thickness portion may be disposed radially outside the cap body, and the coupling portion may be disposed radially outside the reduced thickness portion.

[0075] An outer peripheral bonding surface of the cap may be provided in the bonding portion.

[0076] The first thickness may be a thickness of the bonding portion measured along the axial direction.

[0077] The first thickness may be smaller than a second thickness of the cap measured in the axial direction.

[0078] Thus, the axial dimension of the welding area of ​​the side wall member, that is, the axial dimension of the peripheral bonding surface, is suppressed, so that a welding portion is formed on the entire peripheral bonding surface along the entire axial direction. At the same time, by increasing the second thickness of the cap body that forms the overall shape of the cap, the deformation of the cap due to the internal pressure of the tank can be minimized, thereby improving the strength of the cap itself and the bonding strength between the cap and the side wall member.

[0079] The reduced thickness portion may be provided on an axially inner surface of the cap.

[0080] When the position of the reduced thickness portion is appropriately selected so that at least a portion of the reduced thickness portion contacts the current collecting plate, an alignment effect of the center of the cap is achieved due to the reduced thickness portion of the cap contacting the current collecting plate during the process of inserting the cap. That is, due to the presence of the reduced thickness portion of the cap, the cap is effectively aligned and centered when the cap is inserted into the can.

[0081] In order to enhance this alignment effect, the reduced thickness portion may include an inclined surface that further extends outward in the axial direction as the reduced thickness portion extends toward the radially outer side of the cap.

[0082] The reduced thickness portion and the joining portion may be formed by forging.

[0083] As the cap is inserted, a radially inner edge of an axially outward end of the cap connecting portion of the current collecting plate may contact the inclined surface of the reduced thickness portion.

[0084] Therefore, the center of the cap can be aligned with the center of the current collecting plate, and the axial outer end of the cap connecting portion of the current collecting plate can be pressed radially outward to be closer to or contact the second inner circumferential surface of the sidewall member.

[0085] The present disclosure provides a method for manufacturing the above-mentioned battery cell.

[0086] The battery cell includes: a can including a bottom member, a side wall member connected to the bottom member and extending in an axial direction, and an open end provided at one axial end of the side wall member; a cap covering the open end; and an electrode assembly accommodated in the can.

[0087] The manufacturing method of the battery cell comprises a first step of combining a current collecting plate to an electrode joint, wherein the electrode joint is arranged at one of two axial ends of an electrode assembly corresponding to an open end.

[0088] The manufacturing method includes a second step of bringing a first section, which is an axial portion of an outer peripheral contact surface of a can connection portion provided at a radial outer edge of the current collecting plate, into contact with an inner peripheral surface of the side wall member when the current collecting plate is inserted into the can.

[0089] Here, the tank connection portion of the current collecting plate is forcibly press-fitted into the first inner peripheral surface provided axially inside the inner diameter enlarged portion of the side wall member so that the attachment strength of the first inner peripheral surface and the outer peripheral bonding surface of the current collecting plate is improved.

[0090] The manufacturing method includes a third step of making the outer peripheral bonding surface and the current collecting plate contact surface provided at the edge of the cap contact the inner peripheral surface of the side wall member and the cap contact surface of the current collecting plate respectively when covering the open end of the side wall member with the cap.

[0091] Here, a thickness reduction portion in the form of an inclined surface provided on the axial inner surface of the cap can be brought into contact with the collecting plate to align the center of the cap, or the axially outward end of the cap contact surface of the collecting plate can be pressed radially outward so as to be closer to or contact the second inner circumferential surface of the side wall member.

[0092] The manufacturing method may include a fourth step of irradiating a laser axially from the axially outer side to a contact area between an inner peripheral surface of the side wall member and an outer peripheral joining surface of the cap to weld together the inner peripheral surface of the side wall member, the outer peripheral joining surface of the cap and the tank connection portion of the collecting plate.

[0093] According to another aspect of the present disclosure, a battery cell may include a can, a cap, an electrode assembly, and a current collector. The can may include an axially extending sidewall member and an open end disposed at a first axial end of the sidewall member. The first axial end of the sidewall member may include a radially inclined first conical portion. The cap may cover the open end of the can. The electrode assembly may be placed in the can. The current collector may electrically connect the electrode assembly and the can. The radially outer portion of the current collector may include a first outer contact surface defined by the outer periphery of the radially outer portion, wherein the outer contact surface faces the inner surface of the sidewall member. The radially outer portion may also include a second surface defined by the axially outward end of the radially outer portion of the current collector, wherein the second surface faces and contacts the axially inward surface of the cap. The cap may include a first outer cap surface facing the inner surface of the sidewall member. The cap may also include an axially inward second cap surface, wherein the second cap surface faces and contacts the radially outer second surface of the current collector.

[0094] In addition, in the above aspects of the present disclosure, the first outer cap surface may be arranged radially and axially outside the second cap surface. At least a portion of the inner surface of the side wall member and at least a portion of the outer contact surface of the current collecting plate may be combined by welding. At least a portion of the inner surface of the side wall member and at least a portion of the first cap surface may be combined by welding. At least a portion of the second surface of the radially outer portion of the current collecting plate and at least a portion of the second cap surface may be combined by welding. At least a portion of the inner surface of the side wall member, at least a portion of the first cap surface, and at least a portion of the radially outer portion of the current collecting plate may be welded together. Before the current collecting plate is inserted into the tank, the outer diameter of the current collecting plate may be greater than the inner diameter of the inner surface of the side wall member, so that the portion of the inner surface of the side wall member in contact with the radially outer outer contact surface of the current collecting plate is press-fitted into the side wall member.

[0095] In addition, in the above aspects of the present disclosure, the tapered portion of the inner surface of the side wall member may taper radially outward as the inclined surface extends axially outward. When the current collecting plate is placed in the tank, the radial outer portion of the current collecting plate may include a bend, and the radial outer portion extends axially outward from the bend. The bend may define a curved surface that bends from the radial direction toward the axial direction, and as the radial outer portion of the current collecting plate extends axially inward, the outer diameter of the current collecting plate may gradually decrease. The minimum outer diameter of the curved surface is less than the minimum inner diameter of the first tapered portion of the side wall member.

[0096] In addition, in the above aspects of the present disclosure, the cap may include a cap body, an inclined surface located radially outside the cap body, and a joint portion arranged radially outside the cap body, the joint portion including a first cap surface and a second cap surface. The first thickness of the joint portion measured axially is less than the second thickness of the cap body measured axially. The inclined surface of the cap body may be arranged on the axial inner surface of the cap, and may extend axially outward as the inclined surface extends radially outward. At least a portion of the inclined surface of the cap body contacts the collector plate.

[0097] In addition, in the above-mentioned aspects of the present disclosure, the inner wall member may include: a first inner circumferential surface, which is adjacent to the first tapered portion and positioned axially inward, and defines a first inner diameter of the tank; and a second inner circumferential surface, which is adjacent to the first tapered portion and positioned axially outward, and defines a second inner diameter of the tank, the second inner diameter being larger than the first inner diameter.

[0098] According to another aspect of the present disclosure, a method for manufacturing a battery cell may include: providing a can, a cap, and an electrode assembly, the can including an axially extending side wall member and an open end disposed at a first axial end of the side wall member, the cap being configured to cover the open end, and the electrode assembly being placed in the can; coupling a current collecting plate to the electrode assembly; inserting the current collecting plate into the can, wherein the step of inserting the current collecting plate includes deforming the radially outer portion of the current collecting plate from a first shape to a second shape; when covering the open end of the side wall member with the cap, contacting the first outer cap surface and the second axially inward cap surface of the cap with the inner surface of the side wall member, and contacting the second cap surface of the cap with the second radially outer surface of the current collecting plate; and irradiating a laser from the axially outer side to a contact area between the inner surface of the side wall member and the first cap surface to weld the inner surface of the side wall member, the first cap surface, and the radially outer portion of the current collecting plate together.

[0099] In addition, in the above aspects of the present disclosure, during the inserting step, the radially outer portion of the current collecting plate may contact the inner surface of the sidewall member. During the step of contacting the first cap surface and the second cap surface with the inner surface of the sidewall member, the inclined surface on the inner surface of the cap may contact the current collecting plate.

[0100] According to another aspect of the present disclosure, a battery cell may include a can, a cap, an electrode assembly, and a current collector. The can may include an axially extending sidewall member and an open end disposed at a first axial end of the sidewall member. The cap may be configured to cover the open end. The electrode assembly may be configured to be received in the can. The current collector is configured to electrically connect the electrode assembly and the can. Before the current collector is placed in the can, the current collector may define a first shape, and when the current collector is placed in the can, the current collector may define a second shape different from the first shape. The radially outer portion of the current collector may include a first outer contact surface defined by the outer periphery of the radially outer portion when the current collector is in the second shape. The first outer contact surface may face the inner surface of the sidewall member. When the current collector is in the second shape, the second surface may be defined by the axially outward end of the radially outer portion of the current collector. When the battery cell is assembled, the second surface may face and contact the axial inner surface of the cap (e.g., the first cap surface). The cap may include a first radially outer surface (e.g., the first cap surface) facing the inner surface of the sidewall member when the battery cell is assembled. The cap may further include a second axially inner surface (eg, a second cap surface). When the battery cell is assembled, the second cap surface may face and contact the radially outer second surface of the current collecting plate.

[0101] In addition, in the above aspects of the present disclosure, in the first shape, the radially outer portion of the current collecting plate may extend radially, and in the second shape, the radially outer portion of the current collecting plate may extend axially. The current collecting plate may be configured to elastically deform from the first shape to the second shape during the process of inserting the current collecting plate into the can. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Figure 1 is a perspective view of a cylindrical battery cell according to one aspect of the present disclosure.

[0103] Figure 2 The electrode assembly is wound and contained in Figure 1 Exploded perspective view of the tank before.

[0104] Figure 3 yes Figure 2 A three-dimensional view of an electrode assembly in a laminated state before winding.

[0105] Figure 4 By winding Figure 3 A three-dimensional view of a cylindrical jellyroll-type electrode assembly assembled from laminated parts.

[0106] Figure 5 is shown with Figure 4 A perspective view of a first current collecting plate coupled to an electrode connector of a first electrode of an electrode assembly.

[0107] Figure 6 is shown with Figure 4A perspective view of an electrode assembly in which an electrode connector of a second electrode is coupled to a second current collecting plate.

[0108] Figure 7 is a side cross-sectional view showing a process of placing an electrode assembly in which a first current collecting plate and a second current collecting plate are combined into a can.

[0109] Figure 8 is a side cross-sectional view illustrating a coupling process of a first current collecting plate and a first electrode terminal of an electrode assembly accommodated in a can.

[0110] Fig. 9 is a side cross-sectional view showing the process of placing a cap to cover the open end of a can having an electrode assembly housed therein.

[0111] Fig.10 and Fig.11 is a side cross-sectional view showing a process of closing a filling port of a cap using a stopper, the cap being coupled to a sidewall member of a can to close the open end.

[0112] Fig.12 yes Fig.11 1 is an enlarged cross-sectional view of an area marked with a two-dot chain line at an open end of a battery cell in FIG. 1 , showing a process of inserting a cap with the electrode assembly housed in a can and a current collecting plate inserted.

[0113] Fig.13 It is shown Fig.12 FIG. 1 is a diagram showing a state in which the cap is inserted.

[0114] Fig.14 yes Fig.13 An enlarged view of the contact area of ​​the side wall member, collector plate and cap.

[0115] Fig.15 It shows that Fig.13 A diagram showing a state in which a side wall member, a current collecting plate and a cap are welded to form a welded portion.

[0116] Fig.16 and Fig.17 is a flow chart of a manufacturing process of a battery cell according to the present disclosure, wherein Fig.16 The present invention is a flow chart of a manufacturing process of a battery cell using a cap provided with a liquid injection port. Fig.17 The present invention is a flow chart of a manufacturing process of a battery cell using a cap without a liquid injection port.

[0117] Fig.18 is a perspective view of a battery pack including a plurality of battery cells according to aspects of the present disclosure.

[0118] Fig.19 Is equipped with Fig.18 Diagram of a battery pack for a car. DETAILED DESCRIPTION

[0119] The above-mentioned objects, features and advantages will be described in detail below with reference to the accompanying drawings so that those skilled in the art can realize the technical concept of the present disclosure. When describing the present disclosure, when it is determined that the detailed description of the prior art related to the present disclosure unnecessarily obscures the main points of the present disclosure, its detailed description will be omitted. Aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are used to represent the same or similar components.

[0120] Although "first", "second", etc. are used to describe various elements, these elements are not limited by these terms. Instead, these terms are only used to distinguish one element from another element, and unless otherwise explicitly stated, a component identified as a first element may also be a second element, and vice versa.

[0121] Throughout the specification, unless otherwise specified, each element may be in the singular or in the plural.

[0122] Hereinafter, “arranging an element at the upper (or lower) part of a component” or “arranging an element at the top (or bottom) of a component” not only means arranging the element to be in contact with the upper surface (or lower surface) of the component, but also means arranging the element above the upper surface (or below the lower surface) with another element interposed therebetween.

[0123] In addition, when an element is described as being “connected to,” “coupled to,” or “in contact with” a component, it should be understood that the element may be directly connected to, directly coupled to, or directly in contact with the component, or the element may be connected to, coupled to, or in contact with the component through one or more other elements interposed therebetween.

[0124] Unless the context clearly dictates otherwise, expressions in the singular form herein include expressions in the plural form.

[0125] Throughout the specification, unless explicitly stated otherwise, “A and / or B” means A, B, or A and B, and “C to D” includes both endpoints and all values ​​in between.

[0126] In the description of the implementation scheme, "axial" refers to the direction in which the central longitudinal axis of the winding center constituting the core-wound electrode assembly extends, that is, the direction parallel to the central longitudinal axis, "radial" refers to the direction toward (centripetal) or away from (eccentric) the axis, and "circumferential" refers to the direction around the axis.

[0127] The following will refer to Figures 1 to 13 One aspect of a battery cell employing the welding structure of the present disclosure is described in detail.

[0128] The battery cell of this aspect of the disclosure may, for example, be a cylindrical battery cell having a form factor ratio (defined as the diameter of the cylindrical battery cell divided by the height, ie, the ratio of diameter Φ to height H) greater than about 0.4.

[0129] The shape factor refers to the numerical value representing the diameter and height of a cylindrical battery cell. A cylindrical battery cell 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 shape factor, the first two numbers represent the diameter of the cell, the next two numbers represent the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

[0130] The battery cell may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0131] A battery cell according to another aspect may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0132] A battery cell according to yet another aspect may be a substantially cylindrical cell having a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0133] The battery cell according to yet another aspect may be a substantially cylindrical cell having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0134] A battery cell according to another aspect may be a substantially cylindrical cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0135] The present disclosure can be applied to the context of battery cells with a form factor ratio of about 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is about 18 mm, the height is about 65 mm, and the form factor ratio is 0.277. For 21700 cells, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0136] The battery cell of the present disclosure includes an electrode assembly 20 , first and second current collecting plates 31 and 32 electrically connected to the electrode assembly 20 , and a can 10 accommodating the electrode assembly 20 and the current collecting plates 31 and 32 therein.

[0137] The 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 .

[0138] The can 10 includes a cap 16 covering its open end.

[0139] The bottom member 12 may have a disc shape with a hole provided at the center thereof, and the sidewall member 11 may have a circular tube shape surrounding the inner volume of the can 10 .

[0140] The bottom member 12 and the side wall member 11 may be manufactured by performing a deep drawing process on a metal plate having a nickel-plated steel surface (but the material is not limited thereto), and then trimming the side wall member 11 with a punch while clamping the front end of the side wall member with a blank holder.

[0141] The first electrode terminal 13 may be loaded and coupled to the hole. The first electrode terminal 13 may be riveted and fixed to the bottom member 12 with the gasket 14 sandwiched therebetween. Specifically, the gasket 14 is interposed between the first electrode terminal 13 and the bottom member 12 to seal the inside and outside of the can 10, thereby preventing electrolyte leakage, and electrically insulating the first electrode terminal 13 from the bottom member 12.

[0142] However, the connection method between the first electrode terminal 13 and the bottom member 12 is not limited thereto. For example, if the resulting structure can form a seal between the first electrode terminal 13 and the bottom member 12 and can also electrically insulate the first electrode terminal 13 from the bottom member 12, various other fixing methods such as a bolt and nut connection method, a glass sealing method, and a PP-MAH (maleic anhydride grafted polypropylene or maleated polypropylene) and a chrome coating thermal bonding method can be used.

[0143] The first electrode terminal 13 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 (described in more detail below) may all have a second polarity.

[0144] Thus, the battery cell may have a first electrode terminal 13 and a second electrode terminal 15, both of which are disposed at an axial end where the bottom member 12 is disposed, such as at the closed end of the can 10. As a result, the battery cell may have a bus bar connected to the first electrode terminal 13 and another bus bar connected to the second electrode terminal 15, both of which are located at the top of the battery cell.

[0145] In one example, the first electrode terminal 13 may be a cathode terminal and the second electrode terminal 15 may be an anode terminal. In other examples, the first electrode terminal 13 may be an anode terminal and the second electrode terminal may be a cathode terminal.

[0146] The electrode assembly 20 is housed or received within the internal volume of the can 10. The electrode assembly 20 is manufactured as follows: Figure 2 As shown, a first electrode 21, a second electrode 22 and a separator 28 extending in the length direction and having a predetermined width are prepared, and then Figure 3 As shown, a laminate is formed by sequentially stacking the first electrode 21, the separator 28, the second electrode 22 and the separator 28, and then Figure 4 As shown, the laminate is coiled into a core shape having a winding mandrel.

[0147] In some examples, the first electrode 21 may be a cathode and the second electrode 22 may be an anode. In other examples, the first electrode 21 may be an anode and the second electrode 22 may be a cathode.

[0148] The first electrode 21 and the second electrode 22 are manufactured in a sheet shape. The electrode sheet is manufactured by coating the active material layer 24 on the surface of the metal foil 23. The electrode sheet includes a coating area 25 coated with the active material layer 24 and a non-coating area 26 not coated with the active material layer 24. The positive electrode sheet is provided with the non-coating area 26 on one side in the width direction, and the negative electrode sheet is provided with the non-coating area 26 on the other side in the width direction.

[0149] The first electrode 21 and the second electrode 22 are arranged in the laminate so that their non-coated regions 26 are exposed or protruded from the laminate in the width direction, wherein the non-coated region 26 of the first electrode 21 protrudes at one axial end of the wound core, and the non-coated region 26 of the second electrode 22 protrudes at the opposite axial end of the core. The non-coated region 26 itself serves as at least one electrode tab 27.

[0150] Notches may be formed at predetermined intervals along the non-coated region 26 so as to define notches in the electrode tab 27. The electrode tab 27 may also be referred to as a notch tab 27 herein.

[0151] Each notch joint 27 can be formed into a flag shape. In the illustrated aspect, the notch joint 27 has an equilateral trapezoidal shape. However, it is conceivable that the notch joint 27 can be alternatively formed into various shapes, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc. In addition, in the illustrated aspect, each notch joint 27 has the same width along the length direction. However, it is also conceivable that the width of the notch joint along the length direction can be gradually widened from the core side to the peripheral side.

[0152] In addition, if Figure 2 and Figure 3 As shown, the height of the notch joint 27 gradually increases from the core side to the outer peripheral side. However, it is also contemplated that the height of the notch joint may be constant, or may gradually decrease.

[0153] In addition, according to the illustrated aspect, the notch joint 27 may be removed or absent from the non-coated regions 26 at both opposite ends of the first electrode 21 and the second electrode 22 along the length direction. However, it is also contemplated that when the electrode assembly 20 is wound into a jellyroll configuration, the notch joint may not be removed from either end, or the notch joint may be removed only from the non-coated region of the radially inner end or the radially outer end.

[0154] In the jellyroll-type electrode assembly 20, the notch joint 27 may be bent in the radial direction and flattened, as shown in FIG. Figure 4 That is, the notch joint 27 can be bent radially inward or outward. However, according to aspects of the present disclosure, the notch joint 27 is bent radially inward as shown.

[0155] The notch tabs 27 may be bent one by one in the process of winding the laminate to form the jellyroll type electrode assembly 20. Alternatively, the notch tabs 27 may be formed by bending all the notch tabs at once after the laminate is wound to form the jellyroll type electrode assembly.

[0156] The notch joint 27 of the first electrode 21 and the notch joint 27 of the second electrode 22 that are bent in the radial direction and overlap each other may define or form a plane substantially perpendicular to the axial direction at each opposite end of the electrode assembly 20 .

[0157] The first and second current collecting plates 31 and 32 may be coupled to a substantially flat surface formed by the bent notch joints 27 exposed at both axial ends of the electrode assembly 20, as shown in FIG. Figure 5 and Figure 6 shown.

[0158] In some examples, the first current collecting plate 31 is a cathode current collecting plate and the second current collecting plate 32 is an anode current collecting plate. The first current collecting plate 31 may be made of aluminum and the second current collecting plate 32 may be made of copper. The current collecting plates 31 and 32 may be manufactured by stamping, trimming, perforating and / or bending metal sheets.

[0159] refer to Figure 5 , the first current collecting plate 31 includes a terminal connection portion 312 extending radially from the center, a ring portion 313 connecting the radial outer end of the terminal connection portion 312 and extending in the circumferential direction, and an electrode connection portion 314 extending radially inward from the ring portion 313 but not connected to the terminal connection portion 312. The center of the terminal connection portion 312 covers at least a portion of the core hollow portion along the central longitudinal axis of the electrode assembly 20. The terminal connection portion 312 is generally formed in an X-shape, which is connected to the ring portion 313 at four connection points that are approximately equidistant from each other around the inner circumference of the ring portion 313. It is contemplated that the terminal connection portion 312 may be formed in other shapes and extend along the first current collecting plate 31 in other forms.

[0160] Before the electrode assembly 20 is inserted into the can 10, the electrode connection part 314 is bonded to the notch joint 27 of the first electrode 21 of the electrode assembly 20 using a method such as laser welding. The welding line of the laser may extend radially.

[0161] refer to Figure 6 , the second current collecting plate 32 defines a hole 322 corresponding to the core hollow portion of the electrode assembly 20. The second current collecting plate 32 includes an inner ring portion 321 surrounding the core hollow portion and an electrode joint connection portion 323 extending radially from the inner ring portion 321. The electrode joint connection portion 323 may be in the form of a plurality of spokes extending radially outward from the inner ring portion, wherein the radial outer end of one or more spokes is connected to the outer peripheral portion of the current collecting plate 32, which is referred to as a can connection portion 324. In addition, the radial outer end of one or more spokes of the electrode joint connection portion 323 may not reach the can connection portion 324. The can connection portion 324 has an outer ring shape surrounding the electrode joint connection portion 323, and the can connection portion 324 may include a step away from the electrode assembly 20 in the axial direction, so that at least the outermost periphery of the can connection portion 324 is farther from the electrode assembly 20 than from other parts of the can connection portion 324 (including the electrode joint connection portion 323 and the inner ring portion 321).

[0162] Before the electrode assembly 20 is inserted into the can 10, the electrode tab connection portion 323 is coupled to the notch tab 27 of the second electrode 22 of the electrode assembly 20 by laser welding or the like. The welding line of the laser may extend radially.

[0163] like Figure 7 and Figure 8 As shown, the electrode assembly 20 is housed in the can 10 in such a manner that the first current collecting plate 31 faces the bottom member 12 of the can 10. The insulator 19 is interposed between the first current collecting plate 31 and the bottom member 12 of the can 10 to electrically insulate the first current collecting plate 31 from the bottom member 12. The terminal connection portion 312 of the first current collecting plate 31 is bonded to the first electrode terminal 13 by resistance welding, ultrasonic welding, laser welding, or the like. The welding device for welding the first current collecting plate 31 and the first electrode terminal 13 can perform welding by entering the inner side of the center of the terminal connection portion 312 of the first current collecting plate 31 (i.e., the side of the terminal connection portion 312 facing the electrode assembly 20). Specifically, the welding device can enter this position of the first current collecting plate 31 from the open end of the can 10 through the core hollow portion of the electrode assembly 20, as shown in FIG. Figure 8 As shown. As an alternative to the above-mentioned welding method, the first current collecting plate 31 and the first electrode terminal 13 may be combined with each other by brazing or soldering. That is, various combining methods may be used as long as the first current collecting plate 31 and the first electrode terminal 13 are fixed to each other and electrically connected.

[0164] When the electrode assembly 20 is accommodated inside the can 10 , the electrode tab 27 of the second electrode 22 and the second current collecting plate 32 will be arranged to face the open end of the sidewall member 11 .

[0165] After the first current collecting plate 31 is combined with the first electrode terminal 13, Fig. 9 and Fig.10 As shown, the open end of the side wall member 11 is covered and closed with the cap 16. Then, the electrolyte solution can be injected into the can 10 through the injection port provided at the center of the cap 16.

[0166] After injecting the electrolyte, Fig.10 and Fig.11 As shown, the filling port 18 can be closed with a plug 40.

[0167] In other embodiments, the welding method of the present disclosure can be applied to a cap without a liquid injection port. In such an example, the electrolyte solution can be injected before the open end of the side wall member 11 is covered with the cap 16, and after the injection of the electrolyte solution is completed, the open end can be covered with the cap 16.

[0168] like Fig.14 As shown, the edge of the cap 16 is joined to the edge of the side wall member 11 by laser seam welding, thereby sealing the can 10. The can 10 is thus in Fig.15 , in which the side wall member 11 , the second current collecting plate 32 and the cap 16 are welded together.

[0169] refer to Fig.12 and Fig.13 , an inner diameter expansion portion 113 is provided at the open end of the side wall member 11. The inner diameter expansion portion 113 includes an inclined surface provided on the radial inner surface of the side wall member 11, so that the inner diameter of the side wall member 11 increases as the side wall member 11 extends axially outward. That is, the inner diameter expansion portion 113 is provided on the inner surface of the side wall member 11, and the inner diameter expansion portion 113 has an inclined surface that extends further radially outward as the inner diameter expansion portion 113 extends axially outward of the side wall member 11. In other words, the side wall member 11 has a first thickness at the second inner surface 115, and the thickness gradually decreases along the inner diameter expansion portion 113 as the side wall member 11 extends axially outward from the second inner surface 115, and the side wall member 11 has a second thickness at the first inner surface 111, and the second thickness is greater than the first thickness at the second inner surface 115, as shown in FIG. Figures 12 to 15As shown. The first inner surface 111 is adjacent to the inner diameter expansion portion 113, so that the axially outward end of the inner diameter expansion portion 113 is connected to the axially inner end of the first inner surface 111. In addition, the second inner surface 115 is adjacent to the inner diameter expansion portion 113 (on the side of the inner diameter expansion portion opposite to the first inner surface 111), so that the axially inner end of the inner diameter expansion portion 113 is connected to the axially outward end of the second inner surface 115. In this way, as the side wall member 11 extends axially inward, the inner surface of the side wall member 11 sequentially transitions from the first inner surface 111 to the inner diameter expansion portion 113, and then to the second inner surface 115.

[0170] Therefore, the radial inner surface of the side wall member 11 may include a first inner surface 111 and a second inner surface 115, wherein the first inner surface 111 is axially positioned inward relative to the inner diameter expansion portion 113 (i.e., below or away from the opening at the open end of the side wall member 11), and the second inner surface 115 is axially positioned outward relative to the inner diameter expansion portion 113 (i.e., above or close to the opening at the open end of the side wall member 11).

[0171] Although the diameter of the outer peripheral surface of the side wall member 11 is uniform in the axial direction, the inner diameter of the second inner surface 115 may be greater than the inner diameter of the first inner surface 111. Therefore, the thickness of the side wall member 11 measured in the radial direction at the portion where the second inner surface 115 is located is smaller than the thickness measured in the radial direction at the portion where the first inner surface 111 is located.

[0172] The tank connection portion 324 disposed at the edge of the second current collecting plate 32 and electrically connected to the tank 10 includes a first portion that faces or contacts the inner surfaces 111, 113, and 115 of the sidewall member 11. In the first portion (i.e., at the radially outer portion of the current collecting plate 32), there is a peripheral contact surface 325 that faces or contacts the inner surfaces 111, 113, and 115 of the sidewall member 11 in the radial direction.

[0173] The tank connection portion 324 (also referred to herein as the radially outer portion of the collector plate 32) includes an outer surface that is configured to contact the cap 16 when the cap is assembled to the tank 10. The outer surface (also referred to as the cap contact surface 326) faces and contacts the axial inner surface of the cap 16 (i.e., the underside of the cap 16) when the cap is assembled to the tank 10.

[0174] The second current collecting plate 32 includes a bent portion 327. The bent portion 327 is a portion of the current collecting plate 32 that is bent axially outward while extending radially outward. The tank connection portion 324 (e.g., radially outer portion) of the second current collecting plate 32 is connected to the electrode joint connection portion 323 through the bent portion 327 and the inner ring portion 321.

[0175] The tank connection portion 324 is connected to the axially outer side of the bent portion 327 and has a shape extending axially outward from the bent portion 327. Therefore, the area and axial length of the outer peripheral contact surface 325 of the second current collecting plate 32 can be further ensured by using the tank 10. It should be noted that the tank connection portion 324 is described as being positioned axially outward relative to the bent portion 327 because it is arranged in accordance with Fig.12 and Fig.13 As shown in Fig.12 and Fig.13 The diagram illustrates the configuration of the current collecting plate 32 after being inserted into the tank 10. However, the current collecting plate 32 is elastically deformable, so the bend 327 can be formed after the current collecting plate 32 is inserted into the tank 10. For example, the current collecting plate 32 can be elastically deformed to an angle of approximately 90 degrees relative to the horizontal plane along which the radial inner portion of the current collecting plate extends. In some examples, the bend 327 can form an angle of between approximately 70 degrees and 85 degrees relative to the horizontal plane due to contact with the inclined inner surface of the side wall member 11. It is contemplated that before being inserted into the tank 10, the current collecting plate 32 can extend along a single plane across its entire diameter. It is also contemplated that before the current collecting plate 32 is inserted into the tank 10, the bend 327 may still exist, but the angle is less than 90 degrees. Fig.12 and Fig.13 Therefore, the cap contact surface 326 can be referred to as the radially outer surface of the current collector plate 32, because the cap contact surface 326 can generally face the radially outward direction before the current collector plate is inserted into the can 10. In addition, before the current collector plate is inserted into the can 10, the outer peripheral contact surface 325 of the current collector plate 32 can face the axial interior, rather than the axially inner surface as shown in FIG. Fig.12 and Fig.13 is shown facing radially outward.

[0176] The material of the second current collecting plate 32 may be softer than that of the sidewall member 11 . The thermal conductivity of the second current collecting plate 32 may be higher than that of the sidewall member 11 .

[0177] For example, the material of the second current collecting plate 32 may include copper, and the material of the sidewall member 11 may include iron.

[0178] The outer diameter of the outer peripheral contact surface 325 of the tank connection portion 324 is greater than the inner diameter of the first inner surface 111. The outer diameter of the outer peripheral contact surface 325 may correspond to (eg, may be approximately equal to or may be smaller than) the inner diameter of the second inner surface 115.

[0179] Therefore, in the process of inserting the second current collecting plate 32 into the open end of the side wall member 11, the bent portion 327 is elastically deformed. Therefore, the outer peripheral contact surface 325 is forcibly press-fitted into the second inner surface 115, so that the outer peripheral contact surface 325 is in close contact with the second inner surface 115 in the radial direction. As a result, the outer diameter of the first section of the outer peripheral contact surface 325 press-fitted into the first inner surface 111 in the axial direction corresponds to the inner diameter of the first inner surface 111.

[0180] In this way, due to the multi-stage inner surface structure of the side wall member 11 and the structure of the tank connection portion 324 of the current collecting plate 32 , at least one section of the outer peripheral contact surface 325 in the axial direction is reliably in close contact with the radial inner surface of the side wall member 11 .

[0181] The bent portion 327 provides a curved surface, wherein the outer diameter of the bent portion 327 gradually decreases relative to the outer diameter of the tank connection portion 324 near the axial inner side of the bent portion 327. In addition, the minimum outer diameter d of the curved surface measured at the lower end of the second current collecting plate 32 may be smaller than the inner diameter of the first inner surface 111. Such a shape guides the tank connection portion 324 to be forcibly press-fitted into the first inner surface 111 during the process of inserting the second current collecting plate 32 into the inner space of the sidewall member 11. Therefore, the forced press-fitting process of the second current collecting plate 32 may be performed more efficiently.

[0182] Finally, according to the present disclosure, no matter what the dimensional tolerance of the components is, as long as the minimum outer diameter d of the bending portion 327 is kept smaller than the inner diameter of the first inner surface 111 of the side wall member 11 and the outer diameter of the peripheral bonding surface 171 of the cap 16 is larger than the inner diameter of the first inner surface 111, it is possible to achieve the effect of ensuring that the radial outer part of the collecting plate 32 including the peripheral contact surface 325 is in close contact with the first inner surface 111 of the side wall member 11.

[0183] Therefore, according to the present disclosure, even if a portion of the laser L is used in the welding process further described below, Fig.14 In the case of penetrating into the interior as shown, the laser L can be prevented from directly irradiating into the tank 10 by the tank connection portion 324 of the second current collecting plate 32 which is elongated along the axial direction, by the forced press-fit portion P between the first inner surface 111 of the side wall member 11 and the first section of the outer peripheral contact surface 325 of the second current collecting plate 32, and the inner diameter expansion portion 113 of the side wall member 11.

[0184] The cap 16 includes, in order from the center to the outside in the radial direction: a cap body 160, a thickness reduction portion 161 (a position where the thickness of the cap changes), and a coupling portion 17. That is, the cap body 160 is located in the central area of ​​the cap 16, the thickness reduction portion 161 is arranged radially outside the cap body 160, and the coupling portion 17 is arranged radially outside the thickness reduction portion 161, thereby defining an annular area of ​​the cap 16 where the thickness is reduced relative to the cap body 160. That is, the first thickness t1 of the coupling portion 17 measured in the axial direction is less than the second thickness t2 of the cap body 160 measured in the axial direction.

[0185] Along the radial outer surface of the cap 16, specifically along the radial outer surface of the joint 17, there is provided an outer peripheral joint surface 171 (also referred to herein as the first cap surface of the cap 16), which radially faces the vicinity of the second inner surface 115 of the side wall member 11 or contacts the second inner surface 115 of the side wall member 11. In addition, the lower side of the cap 16 along the joint 17 includes a collector plate contact surface 173 (also referred to herein as the second cap surface of the cap 16) facing downward in the axial direction so as to contact the cap contact surface 326 of the tank connection portion 324 of the second collector plate 32 (also referred to as the radially outer second surface of the collector plate 32).

[0186] The position of the reduced thickness portion 161 is selected so that at least a portion of the reduced thickness portion 161 contacts the second current collecting plate 32. This contact is beneficial so that when the reduced thickness portion 161 of the cap 16 contacts the second current collecting plate 32 during the process of inserting the cap 16 into the open end of the side wall member 11, the center of the cap 16 is effectively aligned. In the illustrated aspect, in order to improve the alignment effect, the reduced thickness portion 161 is implemented in the form of an inclined surface, which extends further outward in the axial direction as the cap 16 extends radially outward. That is, the reduced thickness portion 161 is defined by an inclined surface, and the thickness of the cap 16 measured in the axial direction is reduced along the inclined surface. In this way, the axial inner surface of the cap body 160 extends along a first plane, and the collector plate contact surface 173 of the cap 16 (also referred to as the second axial inward surface of the cap 16) extends along a second plane, which second plane can be basically parallel to the first plane and is positioned axially outward relative to the first plane due to the inclined surface between the axial inner surface of the cap body 160 and the collector plate contact surface 173 of the cap 16.

[0187] In the process of inserting the cap 16 into the side wall member 11, the reduced thickness portion 161 having the inclined surface may contact the radial inner edge of the cap contact surface 326. Therefore, the axially outward end of the tank connection portion 324 of the second current collecting plate 32 including the cap contact surface 326 is pressed radially outward by the reduced thickness portion 161, so that the axially outward end of the tank connection portion 324 is closer to the second inner surface 115 of the side wall member 11 or is in closer contact with the second inner surface 115 of the side wall member 11.

[0188] That is, in the process of inserting the cap 16 into the open end of the side wall member 11, the thickness reduction portion 161 in the form of an inclined surface contacts the tank connection portion 324 of the second current collecting plate 32, which can not only guide the cap 16 to align with the center of the second current collecting plate 32, but also press the axially outward end of the tank connection portion 324 of the second current collecting plate 32 toward the radial outside, so that the axially outward end of the tank connection portion 324 of the second current collecting plate 32 is in close contact with, or even in close abutment with, the second inner surface 115 of the side wall member 11. The combination of forces generated by the shapes of the components forms a tight press fit, thereby creating a secure package of the elements contained in the battery.

[0189] When the cap 16 is inserted into the open end of the side wall member 11, each of the outer peripheral joint surface 171 of the cap 16 and the outer peripheral joint surface 325 of the second current collecting plate 32 radially faces the second inner surface 115 of the side wall member 11 or is in close contact with the second inner surface 115 of the side wall member 11. In other words, the outer peripheral joint surface 171 of the cap 16 may radially face or contact the second inner surface 115, and the outer peripheral contact surface 325 of the tank connection portion 324 may radially face or contact the second inner surface 115 at a portion of the second inner surface 115 axially inward / lower than a portion of the second inner surface 115 abutting or facing the outer peripheral joint surface 171.

[0190] In addition, in the axial direction, the cap contact surface 326 provided on the axially outer end surface of the tank connection portion 324 of the second current collecting plate 32 contacts the current collecting plate contact surface 173 provided on the inner surface of the coupling portion 17 of the cap 16 .

[0191] According to such an assembly structure, the insertion depth of the cap 16 can be precisely adjusted by the height H of the second current collecting plate 32 , which in turn is affected by the axial extension length of the tank connecting portion 324 .

[0192] At the same time, even if there may be errors in the outer diameter size of the outer diameter size of the outer peripheral bonding surface 171 of the cap 16, the inner diameter size of the second inner surface 115 of the side wall member 11 and / or the outer peripheral size of the second collecting plate 32, resulting in the outer peripheral bonding surface 171 of the cap 16 and the outer peripheral contact surface 325 of the second collecting plate 32 not being in close contact with the second inner surface 115 of the side wall member 11, there will be no risk of the welding laser L penetrating into the tank 10 due to the structure of the forced press-fit portion P and the inner diameter expansion portion 113.

[0193] A weld W is formed along the contact area between the side wall member 11, the second current collecting plate 32 and the cap 16, specifically where the second inner surface 115 of the side wall member 11, the peripheral bonding surface 171 of the cap 16 and the tank connection portion 324 of the second current collecting plate 32 are welded together.

[0194] As shown, the outer peripheral joint surface 171 of the cap 16 and the upper axial ends of the radially inner surface of the side wall member 11 , which are in contact with each other in the radial direction, are exposed along the outside of the battery cell.

[0195] The welded portion W is formed by irradiating laser in the axial direction from the outside of the battery cell, and faces the axial end portions of the outer peripheral joining surface 171 of the cap 16 and the second inner surface 115 of the side wall member 11 .

[0196] Since the outer peripheral contact surface 325 of the second current collecting plate 32 is disposed axially inside / below the cap 16 and in contact with the radial inner surface of the side wall member 11, it is possible to prevent the laser from being irradiated into the inner volume of the tank through any gap that may exist between the side wall member 11 and the cap 16. In addition, the inner diameter enlarged portion 113 of the side wall member 11 also prevents the laser from being irradiated and penetrating the gap between the side wall member 11 and the cap 16 or between the side wall member 11 and the second current collecting plate 32.

[0197] The welding portion W includes: a portion where at least a portion of the radial inner surface of the side wall member 11 is combined with at least a portion of the outer peripheral contact surface 325 of the collecting plate 32; a portion where at least a portion of the radial inner surface of the side wall member 11 is combined with at least a portion of the outer peripheral bonding surface 171 of the cap 16; and a portion where at least a portion of the cap contact surface 326 of the collecting plate 32 is combined with at least a portion of the collecting plate contact surface 173 of the cap 16.

[0198] That is, the welded portion W may be formed by triple welding.

[0199] The contact area between the side wall member 11 and the cap 16 is heated to a high temperature by the irradiated laser light L, so that a welded portion W is formed.

[0200] Therefore, the heat generated by the laser in the side wall member 11 can be dispersed and conducted relatively quickly through the second current collecting plate 32 with a larger contact surface area, while the heat generated by the laser in the cap 16 can be dispersed and conducted relatively slowly through the second current collecting plate 32 with a smaller contact surface area. Therefore, the melting time of the side wall member 11, which is relatively thinner than the joint 17 of the cap 16, can be further delayed.

[0201] In addition, since a portion of welding heat transferred through the sidewall member 11 is dispersed through the second current collecting plate 32 , heat transfer to the separator 28 of the electrode assembly 20 contacting the first inner surface 111 of the sidewall member 11 may be further reduced.

[0202] Meanwhile, as described above, in the cap 16, the first thickness t1 of the joint 17 is smaller than the second thickness t2 of the cap body 160 measured in the axial direction. Therefore, the depth to which the cap 16 must be welded to the side wall member 11 is determined by the first thickness t1, and the resistance to the expansion phenomenon of the cap 16 caused by the increase in the internal pressure of the can 10 due to thermal runaway of the battery cell, etc. is determined by the second thickness t2.

[0203] According to the present disclosure, even when the welding between the cap 16 and the side wall member 11 is performed to the first thickness t1, the contact area of ​​the cap 16 and the side wall member 11 (i.e., the area where the cap 16 contacts the side wall member 11) is completely bonded, thereby preventing expansion in the stress concentration area, while providing greater expansion resistance because the cap body 160 has a second thickness t2 that is greater than the first thickness t1 at the radially outer part of the cap 16.

[0204] In addition, according to the present disclosure, the reduced thickness portion 161 of the cap 16 for interacting with the tank connection portion 324 during the assembly process is disposed at a radially inward position of the peripheral bonding surface 171, and its distance substantially corresponds to the thickness of the tank connection portion 324 in the radial direction, so that the area of ​​the cap body 160 having the second thickness t2 can be ensured to be wider, thereby increasing the anti-expansion property. Generally, since the current collecting plate (e.g., the second current collecting plate 32) is manufactured by pressing a thin metal sheet with a press, it should be understood that the reduced thickness portion 161 can be disposed very close to the radial outer edge of the cap 16.

[0205] According to the above-mentioned various aspects, despite a wide range of welding processes, sealing force can be ensured without perforation or leakage, and welding performance can be improved. In addition, process stability can be improved by preventing thermal damage to battery components or separators caused by welding heat, and dimensional stability and expansion resistance can be obtained by suppressing dimensional deformation due to internal pressure, thereby increasing durability.

[0206] The following will refer to Figures 7 to 11 as well as Fig.16A first aspect of the method for manufacturing the battery cell will be described below.

[0207] According to the manufacturing method of the battery cell, the can 10 having the first electrode terminal 13 fixed to the bottom member 12 is first prepared, and then the electrode assembly 20 having two axially opposite ends respectively coupled to the first and second current collecting plates 31 and 32 is prepared.

[0208] Subsequently, the electrode assembly 20 is placed in the can 10 so that the first current collecting plate 31 faces the bottom member 12. As a result, the second current collecting plate 32 is located on the open end side of the can 10. In the process of placing the electrode assembly 20 in the can 10, the outer peripheral contact surface 325 of the can connection portion 324 provided at the radial outer edge of the second current collecting plate 32 is brought into contact with the second inner surface 115 of the sidewall member 11.

[0209] Next, the first current collecting plate 31 is combined with the first electrode terminal 13 .

[0210] In addition, when the open end of the side wall member 11 is covered with the cap 16, the peripheral bonding surface 171 and the current collecting plate contact surface 173 provided at the edge of the cap 16 are respectively contacted with the second inner surface 115 of the side wall member 11 and the cap contact surface 326 of the second current collecting plate 32.

[0211] Here, as described above, the thickness reduction portion 161 defining the inclined surface provided on the axial inner surface of the cap 16 may contact the second current collecting plate 32 so that the center of the cap 16 is aligned with the center of the battery cell, and the axially outward end of the tank connection portion 324 may be pressed against the radially outer side of the tank 10 to contact the second inner surface 115. That is, after the current collecting plate 32 is inserted into the tank 10, the radially outer portion of the current collecting plate 32 (e.g., the tank connection portion 324) is elastically deformed to bend in the axial direction, and the outer portion of the tank connection portion 324 may extend at an angle slightly less than 90 degrees relative to the horizontal plane along which the inner portion of the current collecting plate extends. Since the radially inner surface of the side wall member 11 has a sloped surface, the angle of the tank connection portion 324 may be slightly less than 90 degrees.

[0212] Subsequently, the laser is irradiated from the axially outer side along the axial direction onto the contact area between the second inner surface 115 of the side wall member 11 and the outer peripheral bonding surface 171 of the cap 16 to triple-weld the radial inner surface of the side wall member 11, the bonding portion 17 of the cap 16, and the tank connection portion 324 of the second current collecting plate 32. Therefore, the weld W combines all of the side wall member 11, the cap 16, and the second current collecting plate 32.

[0213] Next, the electrolyte is injected into the tank 10 through the injection port 18 of the cap 16. After the electrolyte injection is completed, the injection port 18 is sealed with a plug 40. The injection port 18 can be sealed by welding, for example. However, various known techniques that can be sealed by bonding can also be used.

[0214] refer to Fig.17 , a second aspect of the battery cell manufacturing method will be described. When a cap without a liquid injection port is used, the manufacturing method of the second aspect can be applied.

[0215] First, the can 10 having the first electrode terminal 13 fixed to the bottom member 12 is prepared, and the electrode assembly 20 having both opposite axial ends coupled to the first and second current collecting plates 31 and 32 , respectively, is prepared.

[0216] Subsequently, the first current collecting plate 31 is guided toward the bottom member 12, and the electrode assembly 20 is inserted into and placed in the can 10. Therefore, the second current collecting plate 32 is now located at the open end of the can 10. In the process of placing the electrode assembly 20 in the can 10, the outer peripheral contact surface 325 of the can connection portion 324 provided on the radially outer side of the current collecting plate 32 is brought into contact with the first inner surface 111 of the sidewall member 11.

[0217] Next, the first current collecting plate 31 and the first electrode terminal 13 are bonded together.

[0218] Thereafter, the electrolyte solution is injected into the can 10 before covering the open end of the side wall member 11 with the cap 16 .

[0219] After the electrolyte injection is completed, when the open end of the side wall member 11 is covered with the cap 16, the peripheral bonding surface 171 and the current collecting plate contact surface 173 set at the edge of the cap 16 are in contact or facing the second inner surface 115 of the side wall member 11 and the cap contact surface 326 of the second current collecting plate 32 respectively.

[0220] Subsequently, laser is irradiated from the outside of the battery cell in the axial direction to the contact area between the second inner surface 115 of the side wall member 11 and the outer peripheral bonding surface 171 of the cap 16, so as to triple-weld the radial inner surface of the side wall member 11, the bonding portion 17 of the cap 16, and the can connection portion 324 of the second current collecting plate 32 to each other. Therefore, the weld W combines all of the side wall member 11, the cap 16, and the second current collecting plate 32 together.

[0221] The battery cell 72 manufactured by the above-mentioned welding structure and welding process can be placed in the housing 71 of the battery pack 70, as shown in FIG. Fig.18As shown. The battery pack 70 may be constructed using one or more battery modules, each of which is an intermediate form of assembly containing a plurality of battery cells 72. Alternatively, as shown, the battery pack 70 may be constructed directly from a plurality of battery cells 72 without any intermediate battery modules.

[0222] Since the battery cell 72 described above has a large volume, there is no particular difficulty in implementing the battery pack 70 even without using an intermediate structure such as a battery module. In addition, the battery cell 72 has a smaller internal resistance and a higher energy density than a conventional battery cell. Therefore, the energy density of the battery pack 70 including the battery cell 72 can be increased relative to the conventional battery cell.

[0223] The battery pack 70 having such an increased energy density can store the same amount of energy while reducing its volume and weight. Therefore, when the battery pack 70 using the battery cells 72 is installed in a vehicle (e.g., a car 80) that uses electricity as an energy source, Fig.19 As shown, the vehicle's driving range can be further increased and improved in terms of energy.

[0224] Although the above-mentioned seam welding structures and methods are disclosed in the context of cylindrical battery cans, it should be understood that within the scope of the present disclosure, such techniques can be similarly applied to other battery form factors. For example, the relevant battery cells do not need to have a circular cross-sectional profile orthogonal to the central longitudinal axis, but other cross-sectional shapes can be used, including elliptical, square, rectangular, partially circular, etc. In addition, the central longitudinal axis does not need to be oriented orthogonal to the bottom member and / or cap at the corresponding opposite ends. As an example, the sidewall member of the can (together with the internal components of the can) can form a tube extending along an axis that is oriented obliquely relative to the plane defined by the bottom member and / or the cap. In addition, the welding techniques disclosed herein can also be used outside the context of cylindrical battery cans, and can also be applied to batteries with square and pouch-shaped form factors, for example.

[0225] It is contemplated that the components for forming a battery cell described throughout this disclosure may be provided separately, for example, in kit form, or may be formed or manufactured in individual form and then assembled to form a battery cell. For example, components manufactured in individual form may include a can, a cap, an electrode assembly, and a current collector. As described above, the current collector may be configured to have a first shape, for example, extending substantially along a single plane, and the current collector may be elastically deformed from the first shape to a second shape during the process of inserting the current collector into the can.

[0226] According to the present disclosure, the alignment of the side wall member and the current collecting plate and the attachment strength of the area to be welded between the side wall member and the current collecting plate are ensured by the forced press-fit structure of the peripheral contact surface of the current collecting plate relative to the radial inner surface of the side wall member, and the laser used for welding can be prevented from being irradiated axially into the tank through the close contact area.

[0227] According to the present disclosure, the cap connection portion of the current collecting plate is formed to be extended in the axial direction so that even if a portion of laser irradiated in the axial direction for welding penetrates into the gap between the cap connection portion and the side wall member, the laser is not directly irradiated to the inside of the can.

[0228] According to the present disclosure, an inner diameter enlarged portion is formed on the radial inner surface of the side wall member to provide a first inner diameter portion and a second inner diameter portion having different inner diameters. By press-fitting the cap connection portion of the current collecting plate into a smaller diameter section of the radial inner surface of the side wall member axially disposed below the first inner diameter portion, the press-fitting force required during the assembly process is reduced, and the press-fitting force between the current collecting plate and the side wall member is concentrated on the corresponding section, thereby maintaining close contact between them.

[0229] According to the present disclosure, the enlarged inner diameter portion of the side wall member functions as a barrier to prevent the penetration of laser light for welding irradiated in the axial direction, thereby reliably preventing the laser light from being directly irradiated into the can.

[0230] According to the present disclosure, in the axial section of the cap connection portion, the section close to the bent portion is forcibly press-fitted into the first inner diameter portion, thereby further ensuring radial support of the bent portion and the electrode joint connection portion relative to the forced press-fit portion.

[0231] According to the present disclosure, the curved surface provided by the bent portion of the current collecting plate guides forced press-fitting of the current collecting plate during the process of inserting the current collecting plate into the sidewall member, thereby increasing assembly convenience.

[0232] According to the present disclosure, since the cap is inserted to a position where the axial inner surface of the cap contacts the axial outer end of the cap connecting portion of the collecting plate, the insertion depth of the cap can be adjusted by the axial extension length of the cap connecting portion, thereby improving assembly accuracy.

[0233] According to the present disclosure, during the process of inserting the cap, the inclined surface provided on the thickness reduction portion of the cap contacts the cap connection portion of the current collecting plate, so that the center alignment of the cap relative to the center of the current collecting plate can be achieved, thereby improving assembly convenience.

[0234] According to the present disclosure, when the cap is inserted, the axially outer end of the cap connection portion of the current collecting plate can be pressed radially outward by the inclined surface of the thickness reduction portion of the cap, so that the axially outer end of the cap connection portion can be closer to or contact the second inner surface of the side wall member. Therefore, the adhesion of the welding area can be improved.

[0235] According to the present disclosure, it is possible to ensure welding performance capable of welding the side wall member, the cap, and the current collecting plate together.

[0236] According to the present disclosure, the stability of welding the side wall member, the cap and the current collecting plate together can be ensured.

[0237] According to the present disclosure, by welding the side wall member, the cap and the current collecting plate together, the assembly time of the battery cell can be greatly reduced.

[0238] The above aspects should be understood as illustrative rather than restrictive in all aspects, and the scope of the present disclosure is not represented by the above detailed description. In addition, all changes and modifications derived from equivalent concepts and the meaning and scope of the present utility model should be interpreted as included in the scope of the present disclosure.

[0239] As described above, the present disclosure has been described with reference to the illustrative drawings, but the present disclosure is not limited to any aspect and drawings disclosed herein, and those skilled in the art may make various modifications within the technical concept of the present disclosure. In addition, when explaining aspects of the present disclosure, all operational effects produced by the present disclosure are not explicitly described and explained herein, but those of ordinary skill in the art will recognize such foreseeable effects.

[0240] CROSS-REFERENCE TO RELATED APPLICATIONS

[0241] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0073032 filed on June 7, 2023, Korean Patent Application No. 10-2023-0135318 filed on October 11, 2023, and Korean Patent Application No. 10-2024-0069605 filed on May 28, 2024, the disclosures of which are incorporated herein by reference in their entirety.

Claims

1. A battery cell, characterized in that: The battery cell comprises: A tank comprising a side wall member extending in an axial direction and an open end provided at a first axial end of the side wall member, wherein the first axial end of the side wall member comprises a radially inclined first tapered portion; a cap covering the open end; an electrode assembly disposed in the can; and a current collecting plate electrically connecting the electrode assembly and the can; Wherein, the radial outer portion of the current collecting plate includes: a first surface forming an outer contact surface defined by an outer periphery of the radially outer portion, wherein the first surface faces an inner surface of the sidewall member; and a second surface defined by an axially outward end of the radially outer portion of the current collecting plate, wherein the second surface faces and contacts an axially inner surface of the cap, and Wherein, the cap comprises: a first cap surface facing an inner surface of the sidewall member; and A second cap surface, wherein the second cap surface faces axially inward and contacts the radially outer second surface of the current collecting plate.

2. The battery cell according to claim 1, characterized in that: The first cap surface is disposed radially and axially outside the second cap surface.

3. The battery cell according to claim 1, characterized in that: At least a portion of the inner surface of the sidewall member and at least a portion of the first surface of the current collecting plate are bonded by welding.

4. The battery cell according to claim 3, characterized in that: At least a portion of the inner surface of the side wall member and at least a portion of the first cap surface are bonded by welding.

5. The battery cell according to claim 3, characterized in that: At least a portion of the second radially outer surface of the current collecting plate is bonded to at least a portion of the second cap surface by welding.

6. The battery cell according to claim 1, characterized in that: At least a portion of the inner surface of the sidewall member, at least a portion of the first cap surface, and at least a portion of the radially outer portion of the current collecting plate are welded together.

7. The battery cell according to claim 1, characterized in that: Before the current collecting plate is inserted into the can, the outer diameter of the current collecting plate is larger than the inner diameter of the inner surface of the sidewall member, so that the first radially outer surface of the current collecting plate is press-fitted relative to the inner surface of the sidewall member.

8. The battery cell according to claim 1, characterized in that: The first tapered portion of the sidewall member tapers radially outward as the sidewall member extends axially outward.

9. The battery cell according to claim 1, characterized in that: When the current collecting plate is placed in the can, the radially outer portion of the current collecting plate includes a bent portion, and the radially outer portion extends axially outward from the bent portion.

10. The battery cell according to claim 9, characterized in that: The curved portion defines a curved surface that curves from the radial direction toward the axial direction, and wherein the outer diameter of the current collecting plate gradually decreases as the radial outer portion of the current collecting plate extends axially inward, and A minimum outer diameter of the curved surface is smaller than a minimum inner diameter of the first tapered portion of the sidewall member.

11. The battery cell according to claim 1, characterized in that: The cap comprises: hat body; an inclined surface located radially outside the cap body; and A combination portion, the combination portion is arranged on the radial outer side of the cap body, the combination portion includes the first cap surface and the second cap surface, wherein: A first thickness of the coupling portion measured along the axial direction is smaller than a second thickness of the cap body measured along the axial direction.

12. The battery cell according to claim 11, characterized in that: The inclined surface of the cap body is disposed on an axially inner surface of the cap and extends axially outward as the inclined surface extends radially outward.

13. The battery cell according to claim 11, characterized in that: At least a portion of the inclined surface of the cap body is in contact with the current collecting plate.

14. The battery cell according to claim 1, characterized in that: The inner surface of the sidewall member comprises: a first inner surface located adjacent the first tapered portion and axially inwardly thereof and defining a first inner diameter of the can; and A second inner surface is located adjacent to the first tapered portion and axially outward and defines a second inner diameter of the canister, the second inner diameter being greater than the first inner diameter.

15. A kit for assembling a battery cell, characterized in that: The kit includes: a tank including an axially extending sidewall member and an open end disposed at a first axial end of the sidewall member; a cap configured to cover the open end; an electrode assembly configured to be received in the can; and a current collecting plate configured to electrically connect the electrode assembly and the can, wherein the current collecting plate defines a first shape prior to placement of the current collecting plate within the can, and wherein the current collecting plate defines a second shape different from the first shape when the current collecting plate is placed within the can; The radially outer portion of the current collecting plate comprises: a first surface defined by the outer periphery of the radially outer portion when the current collecting plate is in the second shape, wherein the first surface faces an inner surface of the sidewall member; and a second surface defined by the radially outer axially outward end of the current collecting plate when the current collecting plate is in the second shape, wherein the second surface faces and contacts the axially inward surface of the cap when the battery cell is assembled, and Wherein, the cap comprises: a first cap surface that faces the inner surface of the sidewall member when the battery cell is assembled; and A second cap surface faces and contacts the radially outer second surface of the current collecting plate when the battery cell is assembled.

16. The kit according to claim 15, characterized in that In the first shape, the radially outer portion of the current collecting plate extends in the radial direction, and in the second shape, the radially outer portion of the current collecting plate extends in the axial direction.

17. The kit according to claim 15, characterized in that The current collecting plate is configured to be elastically deformed from the first shape to the second shape during insertion of the current collecting plate into the can.

Images