Welding heat shielding member, electrode assembly damage prevention structure using the same, and battery cell using the same

Abstract

The present invention provides a battery cell comprising a can including: a bottom member; a side wall member connected to the bottom member and extending axially from the bottom member to one side; and a cap covering an open end provided at one end of the side wall member in the axial direction; and an electrode assembly housed inside the can. A current collector plate is connected to an electrode tab provided at the second end, which is located on the side of the open end of the can, among the first and second ends respectively arranged on both axial sides of the electrode assembly. The current collector plate comprises: an electrode tab connecting part that contacts the electrode tab and is electrically connected to the electrode tab; a can connecting part provided radially outward from the electrode tab connecting part and contacts the can and is electrically connected to the can; and a conductive connecting part that electrically connects the can connecting part and the electrode tab connecting part. The circumference of one end of the above-mentioned side wall member and the outer circumference of the cap in the radial direction are seam-welded along the circumference, and at least a portion of an insulating member is interposed between the current collector plate and the electrode assembly in the axial direction.

Description

Technology Field

[0001] The present invention relates to a welding heat shielding member applied to prevent welding heat generated during the welding process of a battery can, a current collector plate, and a cap from damaging the separator of an electrode assembly, an electrode assembly damage prevention structure applying the same, and a battery cell applying the same. Background Technology

[0002] The process of manufacturing a battery cell using a cylindrical can comprises the steps of deep drawing a metal sheet to form a circular bottom portion and a circular tubular side wall member connected thereto, accommodating an electrode assembly inside, and then covering the open end of the side wall member with a cap or lid to finish it. For convenience of explanation, the cap or lid will be collectively referred to as a cap below.

[0003] Meanwhile, at the end facing the open end among the axial ends of the electrode assembly, a current collector plate is provided that contacts the electrode tab of the electrode assembly and is electrically connected thereto. The current collector plate is connected to the cap or the side wall member by means such as welding so as to contact the cap or the side wall member and be electrically connected thereto.

[0004] Cylindrical lithium-ion batteries require excellent sealing properties to prevent performance degradation caused by electrolyte leakage and ignition due to contact with air or moisture. To this end, laser seam welding is being developed for the assembly process of cylindrical cans and caps.

[0005] Laser seam welding technology is known to ensure excellent sealing performance and mechanical strength by using a laser to melt and join cans and caps. However, as lasers are high-energy-density heat sources, welding heat can be transferred outside the weld area during welding. Consequently, there is a possibility that other components surrounding the weld area may be damaged by the welding heat.

[0006] In particular, separators in electrode assemblies made of microporous polymer films are more susceptible to damage, such as thermal alteration, loss, and melting, compared to the steel, aluminum, and copper materials constituting the electrode assembly or other components. However, if low-energy-density lasers are used to prevent this, the weld bead width and penetration depth decrease, raising concerns that the sealing performance and mechanical strength of the weld area may be compromised. In other words, there tends to be a trade-off between the potential for separator damage and sealing performance depending on laser output.

[0007] These characteristics make it difficult to optimize laser process parameters. Furthermore, they may narrow the process window during mass production, potentially lowering product yield.

[0008] Therefore, when performing laser seam welding, a method is required to prevent damage to the separator caused by welding heat while using a high-energy-density laser. The problem to be solved

[0009] The present invention has been devised to solve the aforementioned problems and aims to provide a method to prevent welding heat generated during the seam welding process of a battery can from damaging surrounding parts.

[0010] The present invention aims to provide a method for seam welding a battery can with a high energy density laser to ensure welding quality while preventing the welding heat generated from damaging surrounding parts.

[0011] The present invention aims to provide a method for increasing yield by expanding the process window for seam welding of battery cans.

[0012] The present invention aims to provide a method for securing a laser seam welding process margin for battery cans.

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

[0014] The present invention for solving the above-mentioned problem can be applied to a battery cell comprising an electrode assembly, a current collector plate electrically connected to the electrode assembly, and a can accommodating the electrode assembly and the current collector plate.

[0015] The above can comprises a bottom member, a side wall member connected to the bottom member and extending axially to one side, and a cap covering an open end provided at one axial end of the side wall member.

[0016] The outer circumference of the cap is seam welded along the circumference direction along the radial direction and the circumference of one end of the side wall member.

[0017] The above electrode assembly may be in the form of a jelly-roll wound around a predetermined axis.

[0018] An electrode tab is provided at the end facing the open end among the axial ends of the electrode assembly, and the current collector plate can be connected to the electrode tab.

[0019] The above current collector plate may include an electrode tab connection portion that is electrically connected in contact with the electrode tab.

[0020] The above current collector plate may include a can connection portion that is electrically connected in contact with the can.

[0021] The above current collector plate may include a conductive connection connecting the can connection part and the electrode tab connection part.

[0022] The above can connection part and the electrode tab connection part can be electrically connected to each other by the above conductive connection part.

[0023] The above collector plate may include an inner ring.

[0024] The inner ring portion above may define a hole facing the hollow portion of the core of the electrode assembly.

[0025] The above-mentioned collector plate may further include an outer ring extending radially outward from the inner ring in a manner that surrounds the inner ring.

[0026] The above current collector plate may further include at least one first spoke and at least one second spoke that are connected to the inner ring and extend radially outward from the inner ring.

[0027] The first spoke may extend radially outward from a first circumferential position of the inner ring.

[0028] The second spoke may extend radially outward from a second circumferential position of the inner ring that does not overlap with the first position.

[0029] The first spoke and the second spoke may be spaced apart from each other in the circumferential direction.

[0030] The above outer ring may be spaced apart from the first spoke and connected to the second spoke.

[0031] The above outer ring may be spaced radially outward from the radially outer end of the first spoke.

[0032] The above outer ring can be connected to the radially outer end of the above second spot.

[0033] The inner ring may be a closed-loop shape or an open-loop shape.

[0034] The above outer ring may be a closed-loop shape or an open-loop shape.

[0035] Preferably, the outer ring may have a closed-loop shape.

[0036] The electrode tab connection portion can be placed on at least the first spoke.

[0037] The above electrode tab connection part may also be placed at a first position in the circumferential direction of the inner ring.

[0038] The above can connection part can be placed on the above outer ring.

[0039] The above-mentioned challenge connection may be placed on at least the second spoke.

[0040] The above-mentioned challenge connection may also be positioned at a second circumferential position of the inner ring.

[0041] The above-mentioned conductive connection may be further disposed at a third position located between the first position and the second position in the circumferential direction of the inner ring.

[0042] The above-mentioned conductive connection may be further disposed at a first position in the circumferential direction of the inner ring.

[0043] The battery cell includes an insulating member that prevents heat generated during the seam welding process of the side wall member and the cap from being transferred to the electrode assembly.

[0044] At least a portion of the above-mentioned insulating member is interposed between the current collector plate and the electrode assembly in the axial direction.

[0045] The above insulating member may be disposed out of the space between the electrode tab connection part and the electrode assembly in the above axial direction.

[0046] The above insulating member may be disposed out of the space between the first spoke and the electrode assembly in the axial direction.

[0047] Due to the avoidance groove provided in the insulating member, the insulating member may not be interposed axially between the electrode tab connection part and the electrode assembly.

[0048] At least a portion of the above-mentioned insulating member may be disposed between the can connecting portion and the electrode assembly in the axial direction.

[0049] At least a portion of the above insulating member may be disposed between the outer ring and the electrode assembly in the axial direction.

[0050] At least a portion of the above insulating member may be disposed between the second spoke and the electrode assembly in the axial direction.

[0051] At least a portion of the above insulating member may be disposed between the second circumferential position of the inner ring in the axial direction and the electrode assembly.

[0052] At least a portion of the above insulating member may be disposed between the third circumferential position of the inner ring in the axial direction and the electrode assembly.

[0053] At least a portion of the above insulating member may be disposed between the first circumferential position of the inner ring and the electrode assembly in the axial direction.

[0054] At least a portion of the above-mentioned insulating member may be positioned outside the electrode tab connection portion in the radial direction.

[0055] At least a portion of the above-mentioned insulating member may be positioned outward from the first spoke in the radial direction.

[0056] At least a portion of the above-mentioned insulating member may be disposed between two electrode tab connections adjacent in the circumferential direction.

[0057] At least a portion of the above insulating member may be disposed between the first spokes in the circumferential direction.

[0058] The above insulating member can cover the space between the electrode tab connection part and the can connection part in the radial direction.

[0059] The above insulating member can cover the space between the first spoke and the outer ring in the radial direction.

[0060] The above insulating member can cover the space between the inner ring and the outer ring in the radial direction.

[0061] The above insulating member can cover the space between the electrode tab connection part and the conductive connection part in the perimeter direction.

[0062] The above insulating member can cover the space between the first spoke and the second spoke in the circumferential direction.

[0063] The above insulating member can cover the gap between the electrode tab connection part and the can connection part in the radial and / or circumferential direction.

[0064] The above-mentioned insulating member may include a high-heat-resistant polymer material.

[0065] The above insulating member may be made of a material that is substantially non-reactive with the electrolyte.

[0066] The above insulating member can be substantially chemically stable with respect to the electrolyte injected into the can.

[0067] The above-mentioned insulating material may include at least one of polycarbonate (PC), polyethylene naphthalate (PEN), polyetheretherketone (PEEK), and polyethylene terephthalate (PET).

[0068] The above can connecting portion or outer ring may include a first portion in contact with a side wall member and a second portion in contact with a cap.

[0069] The above-mentioned first portion and side wall member can be joined by welding.

[0070] The above second part and the cap can be joined by welding.

[0071] The above first and second parts can be welded at once.

[0072] The above welding may be laser welding.

[0073] The first portion above may be the outer surface of a can connection portion or an outer ring that faces and contacts the inner surface of the side wall member in the radial direction.

[0074] The second portion may be the axial outer surface of the outer ring that faces and contacts the axial inner surface of the cap in the axial direction.

[0075] The above cap may include an outer surface that faces and contacts the inner surface of the side wall member in the radial direction.

[0076] The battery cell may include a welded portion in which the inner surface of the side wall member, the outer surface of the cap, and the first and second portions of the can connection portion or outer ring of the current collector plate are welded together.

[0077] The outer surface of the cap and the outer surface of the can connection part or outer ring can each come into contact with the inner surface of the side wall member.

[0078] The axial end of the outer surface of the cap and the inner surface of the side wall member, which are mutually butted in the radial direction, may be exposed axially outward.

[0079] The above weld can be formed by a laser irradiated from the axial outer side of the battery cell to the axial end of the outer surface of the cap and the inner surface of the side wall member.

[0080] The thermal conductivity of the above current collector plate may be higher than the thermal conductivity of the side wall member. Accordingly, welding heat can be dispersed to the electrode assembly through the current collector plate.

[0081] As the welding heat is conducted through the collector plate, the temperature can gradually decrease. Accordingly, it is preferable that the insulating member be interposed between the collector plate and the electrode assembly at least in a portion corresponding to the initial path through which the welding heat is conducted.

[0082] The location where welding heat is first conducted from the above current collector plate may be the outer ring. The welding heat may be conducted from the current collector plate in the order of the outer ring, the second spoke, the inner ring, and the first spoke, or in the order of the can connection part, the conductive connection part, and the electrode tab connection part.

[0083] Accordingly, the insulating member may be disposed between at least the can connection portion or outer ring of the current collector plate and the electrode assembly. Preferably, the insulating member may be further disposed between the conductive connection portion or second spoke of the current collector plate and the electrode assembly.

[0084] Additionally, the insulating member may be further disposed between at least a portion of the inner ring and the electrode assembly.

[0085] In addition, the welding heat can also be transferred to the electrode assembly by radiation.

[0086] Accordingly, preferably, the insulating member can cover the gap between the electrode tab connection part and the can connection part in the radial and / or circumferential direction, or the gap between the outer ring and the inner ring and the first spoke and the second spoke. Specifically, the insulating member can cover the electrode assembly so that the electrode assembly is not exposed through the gap.

[0087] Laser seam welding can be performed circumferentially along the edge of the collector plate. Accordingly, preferably, the insulating member may include a ring shape extending a predetermined distance radially inward from the edge of the collector plate.

[0088] At this time, the insulating member may have a shape in which at least the portion corresponding to the electrode tab connection portion of the current collector plate or the first spoke is removed. Effects of the invention

[0089] According to the present invention, the effect of welding heat on the electrode assembly can be minimized by applying a welding heat shielding member. Accordingly, seam welding can be performed using a laser with a high energy density.

[0090] According to the present invention, the influence of welding heat on the electrode assembly can be minimized while sufficiently securing the width and penetration depth of the weld bead. Accordingly, the sealing ability and mechanical strength of the weldment can be sufficiently secured, while preventing damage to the separator.

[0091] According to the present invention, the optimization of laser process parameters is easy, the process window can be widened during mass production, and the production yield of the product can be increased by securing a process margin.

[0092] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0093] FIG. 1 is a perspective view of a cylindrical battery cell of an embodiment. FIG. 2 is an exploded view of the electrode assembly before winding, which is housed inside the can of FIG. 1. Figure 3 is a perspective view of the electrode assembly of Figure 2 in a laminated state before winding. FIG. 4 is a perspective view of an electrode assembly in the form of a cylindrical jelly-roll formed by winding the laminate of FIG. 3. FIG. 5 is a perspective view showing the state in which a first current collector plate is bonded to the electrode tab of the first electrode of the electrode assembly. FIG. 6 is a perspective view showing the process of joining a second current collector plate by interposing an insulating member on the electrode tab of the second electrode of the electrode assembly. FIG. 7 is a perspective view showing a state in which a second current collector plate is joined with an insulating member interposed in the electrode tab of the second electrode of the electrode assembly. FIG. 8 is a side cross-sectional view showing the process of housing an electrode assembly with a current collector plate attached inside a can. FIG. 9 is a side cross-sectional view showing the joining process of the first current collector plate and the first electrode terminal of the electrode assembly housed in a can. FIG. 10 is a side cross-sectional view showing the process of covering the open end of a can containing an electrode assembly with a cap. FIG. 11 is a side cross-sectional view showing the open end of a can containing an electrode assembly covered with a cap. FIG. 12 is a side cross-sectional view showing the process of injecting electrolyte through the injection port of the cap after seam welding the side wall members of the cap and the can. FIG. 13 is a side cross-sectional view showing the state in which the injection port of the cap is sealed with a stopper after the injection of the electrolyte is completed. FIG. 10 is a cross-sectional view showing an enlarged view of the open end portion of a battery cell with the open end of the can covered by a cap. FIG. 14 is an enlarged view of the side wall member, current collector plate, and cap portion to be welded in the battery cell of FIG. 11. FIG. 15 is a drawing showing the process of forming a weld by welding the side wall member, the collector plate, and the cap part in FIG. 14. Fig. 16 is a plan view of the second collector plate. Figure 17 is a plan view of an insulating member. FIG. 18 is a plan view showing an insulating member superimposed on a second collector plate. FIG. 19 is a cross-sectional view taken along line XIX-XIX of FIG. 18. FIG. 20 is a cross-sectional view of XX-XX of FIG. 18. FIG. 21 is a flowchart of the battery cell manufacturing process of an embodiment according to the present invention. FIG. 22 is a flowchart of a battery cell manufacturing process of a modified example according to the present invention. FIGS. 23 and FIGS. 24 illustrate a battery pack to which the battery cells of an embodiment are applied, and a vehicle equipped with such a battery pack. Specific details for implementing the invention

[0094] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0095] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0096] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0097] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0098] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0099] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0100] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0101] In describing the embodiments, the term "axial direction" refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the term "radial direction" refers to the direction toward (central) or toward (centrifugal) the axis, and the term "circumferential direction" refers to the direction surrounding the axis.

[0102] Hereinafter, with reference to FIGS. 1 to 20, an embodiment of a battery cell to which the welded heat shielding member, i.e., the thermal insulation member of the present invention is applied will be described in detail.

[0103] The battery cell of the embodiment may be a cylindrical battery cell in which the ratio of the form factor (defined as the ratio of the diameter of the cylindrical battery cell to the height, i.e., the ratio of the diameter (Φ) to the height (H)) is approximately greater than 0.4.

[0104] Here, the form factor refers to a value representing the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value representing the form factor, the first two digits represent the diameter of the cell, the next two digits represent the height of the cell, and the last digit 0 indicates that the cross-section of the cell is circular.

[0105] The battery cell may be a cylindrical battery cell that is approximately cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0106] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0107] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0108] A battery cell according to another embodiment may be a cylindrical battery cell having a roughly cylindrical shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0109] A battery cell according to another embodiment may be a cylindrical battery cell having a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0110] The present invention may, of course, be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. In the case of 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. In the case of 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0111] The battery cell of the embodiment includes an electrode assembly (20), a current collector plate (31, 32) electrically connected to the electrode assembly (20), and a can (10) that accommodates the electrode assembly (20) and the current collector plate (31, 32).

[0112] The can (10) comprises a bottom member (12), a side wall member (11) connected to the bottom member (12) and extending axially, and a cap (16) covering an open end provided at one axial end of the side wall member (11).

[0113] The bottom member (12) may be in the shape of a disc with a hole formed in the center, and the side wall member (11) may be in the shape of a circular tube.

[0114] The bottom member (12) and the side wall member (11) can be manufactured by forming a metal sheet with nickel plated on the surface of steel using a deep drawing process, and then trimming the front end of the side wall member (11) with a punch while holding it with a blank holder. Of course, the material of the can (10) is not limited to this.

[0115] A first electrode terminal (13) can be fitted into the hole. The first electrode terminal (13) can be fixed by riveting to the bottom member (12) with a gasket (14) interposed therebetween. The gasket (14) is interposed between the first electrode terminal (13) and the bottom member (12) to seal the inside and outside of the can (10) to prevent leakage of the electrolyte and to electrically insulate the first electrode terminal (13) and the bottom member (12).

[0116] However, the method of connecting the first electrode terminal (13) and the bottom member (12) is not limited to this. For instance, if there is a structure that can seal the space between the first electrode terminal (13) and the bottom member (12) and electrically insulate the first electrode terminal (13) and the bottom member (12), various other fixing methods, such as a bolt-nut connection method, a glass seal method, or a chrome coating & PP-MAH heat bonding method, can also be applied.

[0117] 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) to be described later connected to the side wall member (11) may all have a second polarity.

[0118] Accordingly, the battery cell may have both the first electrode terminal (13) and the second electrode terminal (15) disposed at the axial end, i.e., the closed end, which is equipped with a bottom member (12). Then, the busbar connected to the first electrode terminal (13) and the busbar connected to the second electrode terminal (15) may both be located at the top of the battery cell.

[0119] In one example, the first electrode terminal (13) may be a positive terminal and the second electrode terminal (15) may be a negative terminal. Of course, the opposite may also be true.

[0120] An electrode assembly (20) is accommodated in the can (10). The electrode assembly (20) is prepared by preparing a first electrode (21), a second electrode (22), and a separator (28) that have a predetermined width and extend in the longitudinal direction as shown in FIG. 2, forming a laminate by stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28) in the order shown in FIG. 3, and then winding it around a core axis as shown in FIG. 4 to produce a jelly-roll shape.

[0121] The first electrode (21) may be an anode, and the second electrode (22) may be a cathode. Of course, the opposite may also be true.

[0122] The first electrode (21) and the second electrode (22) are manufactured in the form of a sheet. The electrode sheet is manufactured in a form in which an active material layer (24) is coated on the surface of a metal foil (23). The electrode sheet has a retaining portion (25) where the active material layer (24) is coated and a non-retaining portion (26) where the active material layer (24) is not coated. The positive electrode sheet has a non-retaining portion (26) on one side in the width direction, and the negative electrode sheet has a non-retaining portion (26) on the other side in the width direction.

[0123] The unexposed area (26) is exposed or protrudes in the width direction from the laminate. The unexposed area (26) itself functions as an electrode tab (27).

[0124] In the above-mentioned blank portion (26), notches can be formed at predetermined intervals to form flag-shaped notching tabs (27).

[0125] In the embodiment, the notching tabs (27) are exemplified as being in the shape of an isosceles trapezoid. However, their shapes may be various shapes such as semicircles, semi-ellipses, triangles, rectangles, parallelograms, etc.

[0126] In addition, the embodiments exemplify a form in which the notching tabs (27) arranged along the longitudinal direction have the same width. However, the width of the notching tabs may be gradually or stepwise widening from the core side to the outer circumference side.

[0127] In addition, the embodiment illustrates a form in which the height of the notching tabs (27) increases stepwise from the core side to the outer circumference side. However, the height of these notching tabs may also be implemented as a constant or gradually decreasing form.

[0128] In addition, in the embodiment, a structure in which a notching tab (27) is removed from a predetermined section of the centripetal end and a predetermined section of the centrifugal end of the bare portion (26) is exemplified. However, it is obvious that a notching tab may not be removed from the centripetal end of the bare portion, and a notching tab may not be removed from the centrifugal end of the bare portion.

[0129] In the jelly roll-shaped electrode assembly (20), the notching tab (27) can be flattened by being bent radially as shown in FIG. 4. The notching tab (27) can be bent radially inward or outward. In the embodiment, a structure in which the notching tab (27) is bent radially inward is exemplified.

[0130] The above notching tabs (27) can be folded one by one during the process of winding the laminate to form a jelly roll-shaped electrode assembly (20). Alternatively, the above notching tabs (27) may be folded all at once after winding the laminate to form a jelly roll-shaped electrode assembly.

[0131] The notching tabs (27) of the first electrode (21) and the notching tabs (27) of the second electrode (22), which are folded and stacked in the radial direction in this way, can each provide a plane that is substantially perpendicular to the axial direction at both axial ends of the electrode assembly (20).

[0132] As shown in FIGS. 5 and 6, a first current collector plate (31) and a second current collector plate (32) can be respectively joined to a substantially flat surface provided by bending a notching tab (27) exposed at both axial ends of the electrode assembly (20).

[0133] In an example, the first current collector plate (31) is exemplified as an anode current collector plate, and the second current collector plate (32) is a cathode current collector plate. The first current collector plate (31) may be made of aluminum, and the second current collector plate (32) may be made of copper.

[0134] The above current collector plates (31, 32) can be manufactured by punching, trimming, piercing, and folding a metal sheet.

[0135] Referring to FIG. 5, the first current collector plate (31) comprises a terminal connection portion (312) extending radially from the center, a ring portion (313) connecting the centrifugal edge of the terminal connection portion (312) in a circumferential direction, and an electrode connection portion (314) extending from the ring portion (313) toward the center 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 of the electrode assembly (20).

[0136] The electrode connection portion (314) is joined to the notching tab (27) of the first electrode (21) of the electrode assembly (20) by a method such as laser welding before the electrode assembly (20) is placed in the can (10). The laser welding line may be extended radially.

[0137] Referring to FIGS. 6, 7, and 16, the second current collector plate (32) comprises an inner ring (321) provided in a shape that surrounds the core hollow portion of the electrode assembly (20) and defines a hole (322) corresponding to the core hollow portion of the electrode assembly (20), a first spoke (326) extending radially from the inner ring (321), a second spoke (327) extending radially from the inner ring (321), and an outer ring (328) positioned on the centrifugal side of the first spoke (326) and connected to the centrifugal end of the second spoke (327). The first spoke (326) and the second spoke (327) are respectively connected to a first position and a second position, which are different positions of the inner ring (321) in the circumferential direction. Additionally, the first spoke (326) and the second spoke (327) are spaced apart from each other in the circumferential direction. Additionally, the outer ring (328) is concentric with the inner ring (321) and is spaced radially outward from the inner ring (321) and the first spoke (326).

[0138] The embodiment illustrates that both the inner ring (321) and the outer ring (328) have a closed-loop shape, but the shape is not necessarily limited thereto. For instance, the inner ring (321) may be in the shape of a "C," and the outer ring (328) may be a plurality of arc shapes formed intermittently and arranged along the circumferential direction.

[0139] The second current collector plate (32) comprises an electrode tab connecting part (323) that is electrically connected by being joined to the electrode tab (27) of the second electrode (22) of the electrode assembly (20), a can connecting part (324) that is electrically connected by being joined to the can (10), and a conductive connecting part (325) that electrically connects the electrode tab connecting part (323) and the can connecting part (324) to each other.

[0140] According to the embodiment, the electrode tab connecting portion (323) is exemplified as being placed on the first spoke (326), but the placement of the electrode tab connecting portion (323) is not limited thereto. For instance, the electrode tab connecting portion (323) may be further placed on the inner ring (321), specifically at a first position in the circumferential direction.

[0141] According to an embodiment, the can connecting portion (324) is exemplified as being placed on the outer ring (328). The embodiment exemplifies that the can connecting portion (324) is placed throughout the entire circumferential direction of the outer ring (328), but the can connecting portion (324) must not necessarily be placed throughout the entire circumferential direction. For example, the can connecting portion (324) may be placed intermittently along the circumferential direction of the outer ring (328).

[0142] According to an embodiment, the conductive connection portion (325) is positioned on the second spoke (327). However, the conductive connection portion (325) may be further positioned at the inner ring (321), specifically at a second position in the circumferential direction, complementary to the positioning of the electrode tab connection portion (323), and may be further positioned at a third position between the first and second positions in the circumferential direction.

[0143] In the embodiment, four first spokes (326) and four second spokes (327) are alternately arranged at 90-degree intervals. That is, the spokes (326, 327) can be arranged at 45-degree intervals. Meanwhile, accordingly, four electrode tab connection parts (323) are provided at 90-degree intervals.

[0144] The can connection part (324) is positioned radially outward from the electrode tab connection part (323).

[0145] The electrode tab connection part (323) and the can connection part (324) are spaced apart in the radial direction. The electrode tab connection part (323) and the conductive connection part (325) are spaced apart in the circumferential direction. Specifically, the first spoke (326) and the outer ring (328) are spaced apart in the radial direction, and the first spoke (326) and the second spoke (327) are spaced apart in the circumferential direction.

[0146] These separated parts can define a "U" shaped separation space (329).

[0147] Accordingly, the current flow path in the second collector plate (32) may be in the order of the electrode tab connection part (323), the conductive connection part (325), and the can connection part (324), or the first spoke (326), the inner ring (321), the second spoke (327), and the outer ring (328), or the reverse order.

[0148] Likewise, the path of welding heat transfer by conduction in the second collector plate (32) may be in the order of the can connection part (324), the conductive connection part (325), and the electrode tab connection part (323), or the outer ring (328), the second spoke (327), the inner ring (321), and the first spoke (326).

[0149] The electrode tab connection portion (323) of the second current collector plate (32) can be joined to the notching tab (27) of the second electrode (22) of the electrode assembly (20) by means such as laser welding before the electrode assembly (20) is placed in the can (10). The laser welding line can be extended radially.

[0150] According to an embodiment, a welding heat shielding member may be interposed between the second collector plate (32) and the electrode assembly (20) to prevent the welding heat of the side wall member (11) and the cap (16), which will be described later, from affecting the separator (28) of the electrode assembly (20). The welding heat shielding member may be an insulating member (18).

[0151] The above-mentioned insulating member (18) is preferably made of a material that is not reactive with the electrolyte and is a high-heat resistant material. The above-mentioned insulating member (18) may be a polymer material. It may be polycarbonate, polyethylene naphthalate, polyether ether ketone, or polyethylene terephthalate.

[0152] Referring to FIGS. 6, FIGS. 7, and FIGS. 16 to 20, the insulating member (18) is interposed axially between the second current collector plate (32) and the electrode assembly (20).

[0153] The above-mentioned insulating member (18) may include an outer ring portion (181) and a centripetal extension portion (182) extending radially inward from the outer ring portion (181).

[0154] The above centripetal extension (182) can be extended inward by a predetermined distance (d) from the radial outer edge of the insulation member (18).

[0155] The above-mentioned insulating member (18) may be provided with an avoidance groove (185) in which a portion corresponding to the electrode tab connection portion (323) of the second current collector plate (32) is deleted. Four of the avoidance grooves (185) may also be provided at 90-degree intervals to correspond to the second current collector plate of the embodiment.

[0156] With the above insulating member (18) interposed between the second collector plate (32) and the electrode assembly (20), the outer ring portion (181) of the insulating member (18) covers part of the gap space (329) with the outer ring (328) of the second collector plate (32), and the center extension portion (182) of the insulating member (18) covers the remainder of the gap space (329) with the second spoke (327) of the second collector plate (32).

[0157] When the portion where the insulation member (18) covers the outer ring (328) of the second collector plate (32) is referred to as the circumferential extension cover portion (186), the circumferential extension cover portion (186) may be defined by a part of the outer ring portion (181).

[0158] And, when the portion where the insulation member (18) covers the second spoke (327) of the second collector plate (32) is called the radius extension cover portion (184), the radius extension cover portion (184) can be defined by a part of the centripetal extension portion (182).

[0159] And, when the portion where the insulation member (18) covers the gap space (329) of the second collector plate (32) is called the gap space cover portion (183), the gap space cover portion (183) can be defined by the remainder of the outer ring portion (181) and the remainder of the centripetal extension portion (182).

[0160] To explain in reverse, the outer ring (328) of the second collector plate (32) is covered by the outer ring portion (181) of the insulation member (18), the second spoke (327) of the second collector plate (32) is covered by the center extension portion (182) of the insulation member (18), and the gap space (329) of the second collector plate (32) is covered by the outer ring portion (181) and the center extension portion (182) of the insulation member (18).

[0161] The above insulating member (18) is interposed axially between the second current collector plate (32) and the electrode assembly (20), and with the avoidance groove (185) of the insulating member (18) aligned with the first spoke (326) or electrode tab connection part (323) of the second current collector plate (32), the first spoke (326) or electrode tab connection part (323) of the second current collector plate (32) is joined to the electrode tab (27) of the second electrode (22) of the electrode assembly (20). This joining can be achieved by irradiating a laser onto the surface of the electrode tab connection part (323), and the laser can be irradiated by scanning in a radial direction. The laser scanning can be performed multiple times and can be performed at multiple locations spaced apart along the circumferential direction.

[0162] When welding the electrode tab connection part (323), the welding is performed while the first spoke (326) is pressed in the direction of the electrode tab (27), so the first spoke (326) is elastically deformed axially from the inner ring (321) and can be in close contact with the electrode tab (27). Accordingly, the first spoke (326) or the electrode tab connection part (323) can be fitted into the avoidance groove (185) of the insulating member (18).

[0163] Then, since the circumferential surface of the first spoke (326) interferes with the circumferential surface of the avoidance groove (185), the position of the insulating member (18) is restricted as shown in FIG. 7 when the electrode tab connection part (323) and the electrode tab (27) of the electrode assembly (20) are welded.

[0164] As illustrated in FIGS. 9 and 10, the electrode assembly (20) is received in the can (10) with the first current collector plate (31) aligned toward the bottom member (12) of the can (10). At this time, an insulator (19) is interposed between the first current collector plate (31) and the bottom member (12) of the can (10) to electrically insulate the first current collector plate (31) and the bottom member (12).

[0165] Furthermore, the terminal connection portion (312) of the first current collector plate (31) is joined to the first electrode terminal (13) fixed to the can (10) by means such as resistance welding, ultrasonic welding, or laser welding. A welding device for welding the first current collector plate (31) and the first electrode terminal (13) can proceed with welding by approaching the back side of the center of the terminal connection portion (312) of the first current collector plate (31) through the hollow core of the electrode assembly (20) from the open end of the can (10). Of course, the first current collector plate (31) and the first electrode terminal (13) may also be joined by methods such as brazing or soldering. In other words, various methods can be applied to the first current collector plate (31) and the first electrode terminal (13) as long as they are a joining method that electrically connects and mutually fixes them.

[0166] When the electrode assembly (20) is housed inside the can (10) and the first current collector plate (31) and the first electrode terminal (13) are joined, the electrode tab (27) of the second electrode (22) and the second current collector plate (32) are positioned to face the open end of the side wall member (11).

[0167] In this state, as shown in FIGS. 10 to 12, the open end of the can (10) is covered with a cap (16), and the edge of the cap (16) is welded to the edge of the side wall member (11) and the second current collector plate (32). Then, an electrolyte is injected into the can (10) through the injection port (162) of the cap (16).

[0168] After injecting the electrolyte, the injection port (162) of the cap (16) is covered with a stopper (164) and sealed as shown in FIG. 13, thereby completing the assembly of the battery cell.

[0169] Unlike the illustrated embodiment, in a structure where the cap (16) is not provided with an injection port, the battery cell assembly may be completed by first injecting the electrolyte into the can (10) before covering the open end of the can (10) with the cap (16), then covering the open end of the can (10) with the cap (16), and welding the edge of the cap (16) to the edge of the side wall member (11) and the second current collector plate (32).

[0170] As illustrated in FIG. 14, the area where the edge of the side wall member (11) and the edge of the cap (16) meet is exposed axially outward. A laser for seam welding this area can be irradiated axially onto the area where the edge of the side wall member (11) and the edge of the cap (16) meet. The area where the laser is irradiated can move relatively along the circumferential direction of the can (10) to continuously form a weld (W).

[0171] In the battery cell above, the weld (W) is formed at the butt joint between the side wall member (11), the cap (16), and the second current collector plate (32).

[0172] As shown in FIG. 15, during the process of forming the weld (W), the welding heat is conducted along the side wall member (11) and also along the second collector plate (32).

[0173] The second current collector plate (32) may be made of a material with a higher thermal conductivity than the side wall member (11), such as copper. The second current collector plate (32) is in contact with the side wall member (11). Therefore, when the welding heat generated in the side wall member (11) by the laser is conducted along the axial direction of the side wall member (11), it is dispersed to the electrode assembly (20) through the second current collector plate (32), thereby preventing the welding heat from being conducted axially along the side wall member (11) and transmitted to the separator (28) portion of the outer surface of the electrode assembly (20) facing the inner surface of the side wall member (11), thereby preventing damage to the separator (28) in that portion.

[0174] Additionally, the welding heat conducted to the second collector plate (32) travels along the outer ring (328), second spoke (327), inner ring (321), and electrode tab connection part (323) of the second collector plate (32). As the movement of the welding heat progresses, the temperature gradually decreases. At this time, since an insulating member (18) is interposed between the outer ring (328) and second spoke (327) of the second collector plate (32), which have relatively high temperatures, and the electrode assembly (20), the high temperature heat is transferred to the inside of the electrode assembly (20) through the electrode tab (27), thereby preventing it from affecting the axial tip of the separator (28).

[0175] According to the embodiment, since the insulating member (18) is extended by a predetermined distance (d) from the radial outer edge, the inner ring (321) can be kept from being covered. Additionally, the insulating member (18) can be kept from covering the electrode tab connection part (323) by means of the avoidance groove (185). Since the temperature of the welding heat reached by conduction to the inner ring (321) and the electrode tab connection part (323) is relatively low, there is no risk that the heat transferred from there to the electrode assembly (20) will damage the separator (28).

[0176] Meanwhile, the insulating member (18) covers the gap (329) of the second current collector plate (32) between the second current collector plate (32) and the electrode assembly (20). Accordingly, the portion of the electrode assembly (20) corresponding to the gap (329) is covered by the insulating member (18).

[0177] Since the outer ring (328) of the second current collector plate (32) is very close to the area where welding heat is generated, there is a risk that heat radiated from the heated outer ring (328) will be transferred through the gap space (329) to the electrode assembly (20) area corresponding to that area.

[0178] However, according to the embodiment, since the insulating member (18) covers the portion of the electrode assembly (20), the radiant heat is shielded so that the radiant heat does not damage the separator (28) of the electrode assembly (20).

[0179] A method for manufacturing the battery cell described above will be explained below with reference to FIG. 21.

[0180] According to the method for manufacturing the battery cell described above, first, a can (10) is prepared in which a first electrode terminal (13) is fixed to a bottom member (12), and an electrode assembly (20) is prepared in which a first current collector plate (31) and a second current collector plate (32) are joined to each of the axial ends. At this time, an insulating member (18) is interposed between the second current collector plate (32) and the electrode assembly (20).

[0181] Then, the electrode assembly (20) is inserted and received into the can (10) such that the first current collector plate (31) faces the bottom member (12). Then, the second current collector plate (32) is positioned at the open end of the can (10). In the process of receiving the electrode assembly (20) into the can (10) in this way, the radial outer edge of the second current collector plate (32) is brought into contact with the inner circumference of the side wall member (11).

[0182] Next, the first current collector plate (31) and the first electrode terminal (13) are joined.

[0183] Then, the open end of the side wall member (11) is covered with a cap (16), and the edge of the cap (16) is brought into contact with the inner surface of the side wall member (11) and the upper edge of the second collector plate (32).

[0184] Next, a laser is irradiated onto the butting portion between the inner surface of the side wall member (11) and the outer surface of the cap (16) to weld the can connection portion (324) of the side wall member (11), the cap (16), and the second collector plate (32) together. Accordingly, the welded portion (W) joins the side wall member (11), the cap (16), and the second collector plate (32).

[0185] At this time, the overhang portion (117) of the side wall member (11), which protrudes further outward in the axial direction than the cap (16), is inserted into the weld area between the inner surface of the side wall member (11) and the outer surface of the cap (16) to sufficiently secure a weld pool.

[0186] Even if the energy density of the above laser is high, because the thermal conductivity of the second collector plate (32) is higher, high-temperature heat can be transferred to the separator (28) on the outer circumference of the electrode assembly (20) through the side wall member (11) without damaging it. In addition, since the insulating member (18) covers the electrode assembly (20), the welding heat transferred through the second collector plate (32) does not affect the separator (28) of the electrode assembly (20).

[0187] After the seam welding is completed, the electrolyte is injected into the interior of the can (10) through the injection port (162) of the cap (16).

[0188] Then, after the electrolyte injection is completed, the injection port (162) of the cap (16) is covered and sealed with a stopper (164). Since the sealing of the stopper (164) can be performed using known techniques, a detailed description is omitted.

[0189] Meanwhile, another embodiment of the method for manufacturing the battery cell described above will be explained below with reference to FIG. 22.

[0190] First, a can (10) is prepared in which a first electrode terminal (13) is fixed to a bottom member (12), and an electrode assembly (20) is prepared in which a first current collector plate (31) and a second current collector plate (32) are joined to each of the axial ends. At this time, an insulating member (18) is interposed between the second current collector plate (32) and the electrode assembly (20).

[0191] Then, the electrode assembly (20) is inserted and received into the can (10) such that the first current collector plate (31) faces the bottom member (12). Then, the second current collector plate (32) is positioned at the open end of the can (10). In the process of receiving the electrode assembly (20) into the can (10) in this way, the radial outer edge of the second current collector plate (32) is brought into contact with the inner circumference of the side wall member (11).

[0192] Next, the first current collector plate (31) and the first electrode terminal (13) are joined.

[0193] In this state, the electrolyte is injected into the can (10) through the open end of the can (10).

[0194] After the injection is completed, the open end of the side wall member (11) is covered with a cap (16), and the edge of the cap (16) is brought into contact with the inner surface of the side wall member (11) and the upper edge of the second collector plate (32).

[0195] Next, a laser is irradiated onto the butting portion between the inner surface of the side wall member (11) and the outer surface of the cap (16) to weld the can connection portion (324) of the side wall member (11), the cap (16), and the second collector plate (32) together. Accordingly, the welded portion (W) joins the side wall member (11), the cap (16), and the second collector plate (32).

[0196] The battery cell (72) produced through the welding structure and welding process described above can be accommodated in the housing (71) of the battery pack (70) as shown in FIG. 23. The battery pack (70) may be constructed using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be constructed directly without a battery module as shown.

[0197] Since the aforementioned battery cell (72) itself has a large volume, there is no particular difficulty in implementing the battery pack (70) even without using an intermediate structure called a battery module. Furthermore, the battery cell (72) has low internal resistance and a higher energy density. Accordingly, the energy density of the battery pack (70) equipped with the battery cell (72) can be implemented at a higher level.

[0198] A battery pack (70) with such increased energy density can store the same amount of energy while reducing its volume and load. Therefore, if a battery pack (70) with such battery cells (72) is installed in a vehicle such as an electric vehicle (80) that uses electricity as an energy source, as shown in FIG. 24, the vehicle's mileage relative to energy can be further increased.

[0199] The embodiments described above should be understood as exemplary in all respects and not limiting, and the scope of the invention will be defined by the claims set forth below rather than by the detailed description above. Furthermore, the meaning and scope of the claims set forth below, as well as all modifications and variations derived from equivalents thereof, should be interpreted as being included within the scope of the invention.

[0200] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized. Explanation of the symbols

[0201] 10: Can 11: Sidewall member 117: Overhang 12: Floor member 13: First electrode terminal (positive terminal) 14: Gasket 15: Second electrode terminal 16: Cap 162: Injection point 164: Stopper 18: Thermal insulation member (welded heat shield member) 181: Outer ring 182: Centripetal extension 183: Separation space cover 184: Radius extension cover part 185: Evasion Home 186: Circular extension cover section 19: Insulator 20: Electrode assembly 21: First electrode 22: Second electrode 23: Metal foil 24: Active material layer 25: Maintenance Department 26: Mujibu 27: Electrode tab (notching tab) 28: Separator 31: First collector plate (positive collector plate) 312: Terminal connection part 313: Ringbu 314: Electrode connection part 32: Second collector plate (negative collector plate) 321: Inner ring section 322: Hall 323: Electrode tab connection 324: Can connector 325: Challenge Connection 326: 1st spoke 327: 2nd spoke 328: Outer Ring 329: Separation space W: Welded part 70: Battery pack 71: Housing 72: Battery cell 80: Vehicle

Claims

Claim 1 A battery cell comprising: a can including a bottom member; a side wall member connected to the bottom member and extending axially from the bottom member to one side; and a cap covering an open end provided at one end of the side wall member in the axial direction; and an electrode assembly contained within the can, wherein a current collector plate is connected to an electrode tab provided at the second end, which is located on the side of the open end of the can among the first and second ends respectively arranged on both axial sides of the electrode assembly, and the current collector plate comprises: an electrode tab connecting part that contacts the electrode tab and is electrically connected to the electrode tab; and a can connecting part provided radially outward from the electrode tab connecting part and contacts the can and is electrically connected to the can. A battery cell comprising: a conductive connection portion electrically connecting the can connection portion and the electrode tab connection portion; wherein the circumference of the one end portion of the side wall member and the outer circumference of the cap in the radial direction are seam welded along the circumference direction, and at least a portion of an insulating member is interposed between the current collector plate and the electrode assembly in the axial direction. Claim 2 A battery cell according to claim 1, wherein at least a portion of the insulating member is disposed radially outward from the electrode tab connection portion. Claim 3 A battery cell according to claim 1, wherein at least a portion of the insulating member is disposed between two circumferentially adjacent electrode tab connections. Claim 4 A battery cell according to claim 1, wherein at least a portion of the insulating member is disposed between the can connecting portion and the electrode assembly in the axial direction. Claim 5 A battery cell according to claim 1, wherein the insulating member covers the space between the electrode tab connecting portion and the can connecting portion in the radial direction. Claim 6 A battery cell according to claim 1, wherein the insulating member covers the space between the electrode tab connection part and the conductive connection part in the circumferential direction. Claim 7 A battery cell according to claim 1, wherein the insulating member is disposed out of the space between the electrode tab connecting part and the electrode assembly in the axial direction. Claim 8 The battery cell according to claim 1, wherein the current collector plate comprises: an inner ring surrounding a hole facing a hollow portion of the winding core of the electrode assembly; at least one first spoke and at least one second spoke extending radially outward from the inner ring and spaced apart from each other in the circumferential direction; and an outer ring extending radially outward from the inner ring in a manner that surrounds the inner ring, wherein the outer ring is spaced apart from the first spoke and connected to the second spoke. Claim 9 A battery cell according to claim 8, wherein the outer ring is a closed-loop shape. Claim 10 A battery cell according to claim 8, wherein the electrode tab connection portion is disposed on at least the first spoke, the conductive connection portion is disposed on at least the second spoke, and the can connection portion is disposed on the outer ring. Claim 11 In claim 8, at least a portion of the insulating member is disposed outwardly from the first spoke in the radial direction, a battery cell. Claim 12 In claim 8, at least a portion of the insulating member is disposed between the first spokes in the circumferential direction, a battery cell. Claim 13 In claim 8, at least a portion of the insulating member is disposed between the second spoke and the electrode assembly in the axial direction, a battery cell. Claim 14 In claim 8, at least a portion of the insulating member is disposed between the outer ring and the electrode assembly in the axial direction, a battery cell. Claim 15 In claim 8, the insulating member is a battery cell disposed out of the space between the first spoke and the electrode assembly in the axial direction. Claim 16 In claim 8, the insulating member covers the space between the first spoke and the outer ring in the radial direction, a battery cell. Claim 17 In claim 8, the insulating member covers the space between the first spoke and the second spoke in the circumferential direction, a battery cell. Claim 18 In claim 8, the insulating member covers the space between the inner ring and the outer ring in the radial direction, a battery cell. Claim 19 A battery cell according to claim 1, wherein the insulating member comprises a high heat-resistant polymer material. Claim 20 In claim 19, the insulating member is substantially chemically stable with respect to the electrolyte injected into the can, a battery cell. Claim 21 In claim 20, the insulating member is substantially non-reactive to the electrolyte, in a battery cell. Claim 22 In claim 19, the insulating member comprises at least one of PC, PEN, PEEK, and PET, forming a battery cell.

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