Welding structure of battery can, current collecting plate and cap, and battery cell using same

Abstract

The present invention provides a welding structure of a battery can, a current collecting plate, and a cap, a battery cell using same, and a manufacturing method therefor. The current collecting plate of the battery cell includes: a main body part connected to an electrode tab of an electrode assembly; a can connection part disposed on the radial direction outer side of the main body part and connected to a sidewall member and / or the cap; and a bridge having a radial direction inner side that is connected to the main body part, and having a radial direction outer side that is connected to the can connection part and extends in the radial direction. The bridge includes: a first bent part bent such that the extension direction of a bridge part extending toward the radial direction outer side faces an axial direction outer side; a second bent part bent such that the extension direction of the bridge part extending toward the axial direction outer side faces the radial direction outer side; and an offset bridge part having a radial direction inner side connected to the first bent part and a radial direction outer side connected to the second bent part. Therefore, the influence of welding heat of the can and the cap on the electrode assembly through the current collecting plate can be minimized.

Description

Welding structure of battery can, collector plate and cap and battery cell using the same

[0001] The present invention relates to a welding structure of a battery can, a current collector plate, and a cap, and a battery cell using the same.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0149868, filed on November 2, 2023, and all contents disclosed in the specification and drawings of the said application are incorporated by reference into this application.

[0003] The process of manufacturing a battery cell using a cylindrical can includes the steps of deep drawing a metal sheet to form a circular bottom portion and a circular tubular side wall member connected thereto, accommodating an electrode assembly therein, and then closing the open end of the side wall member with a cap.

[0004] Meanwhile, at one of the axial ends of the electrode assembly facing the open end, a current collector plate is provided that contacts and is electrically connected to the electrode tab of the electrode assembly. The current collector plate is connected to the cap or the side wall member by welding or the like so that it contacts and is electrically connected to the cap or the side wall member.

[0005] When closing the open end of a cylindrical can, a process of connecting the current collector to the cap or the side wall member, and a process of connecting the cap to the side wall member are performed separately. This increase in labor costs reduces the production efficiency of cylindrical battery cells and increases the production cost.

[0006] To reduce the number of individual welding processes, a method of welding the sidewall members, cap, and current collector simultaneously may be considered. This welding can be accomplished using a laser.

[0007] However, it is not easy to assemble three parts (sidewall member, cap, and collector plate) that are not fixed to each other so that they are strong enough to be welded.

[0008] Furthermore, when laser irradiation is performed on the sidewall member, cap, and collector plate in a state in which they are simply assembled, gaps may occur due to tolerances among the individual components of the sidewall member, cap, and collector plate, as well as assembly errors. If laser irradiation is performed to assemble these in a state in which such gaps exist, the laser may directly penetrate the interior of the can, causing damage to the electrode assembly required inside the can. Furthermore, such tolerances may lead to inaccurate assembly or deformation of components during the assembly process.

[0009] Meanwhile, if the cap and can have high melting points, the welding area must be heated above their melting points to weld them. Furthermore, the can, cap, and current collector are made of metals with high thermal conductivity. Therefore, the heat generated during welding can affect the electrode assembly contained within the can, potentially deteriorating the electrode assembly or electrolyte during the welding process.

[0010] The present invention has been devised to solve the above-described problems, and provides a welding structure of a battery can, a collector plate, and a cap, which facilitates assembly of the can, the collector plate, and the cap, enables correct positioning and close contact through a mutually abutting structure during the assembly process, and suppresses deformation of the parts during the assembly process even when there is a dimensional tolerance of the parts, and enables accurate assembly, and a battery cell using the welding structure.

[0011] In addition, the present invention aims to provide a welding structure of a battery can, a collector plate, and a cap, and a battery cell using the welding structure, which can increase the energy density of a battery cell while minimizing the impact of heat generated during the welding process on components inside the battery cell.

[0012] In addition, the present invention aims to provide a welding structure of a battery can, a current collector plate, and a cap, and a battery cell using the same, which can increase the production efficiency of a cylindrical battery cell and reduce the production cost by integrating the process of welding a current collector plate to a can and the process of welding the cap to the side wall member into a single welding process.

[0013] In addition, the present invention aims to provide a welding structure of a battery can, a current collector plate, and a cap, and a battery cell using the same, which can prevent a laser from directly penetrating into the can during a laser welding process even if component tolerances and assembly errors occur between the side wall member, the cap, and the current collector plate.

[0014] In addition, the present invention aims to provide a welding structure of a battery can, a current collector plate, and a cap, and a battery cell using the welding structure, which has shapes of the can, a current collector plate, and a cap and an interlocking relationship thereof that can secure weldability, increase process stability, and guarantee durability of welding.

[0015] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0016] The present invention, which aims to solve the above-described problem, can be applied to a battery cell including an electrode assembly, a current collector electrically connected to the electrode assembly, and a can that accommodates the electrode assembly and the current collector.

[0017] The can includes a side wall member extending in an axial direction, and an open end provided at one axial end of the side wall member.

[0018] The above battery cell includes a cap covering the open end.

[0019] A floor member is connected to the other axial end of the side wall member, and thus the other axial end of the side wall member can form a closed end.

[0020] The above electrode assembly may be in the form of a jelly-roll wound around a predetermined axis.

[0021] An electrode tab is provided at one of the axial ends of the electrode assembly corresponding to the open end, and the current collector plate can be electrically connected to the electrode tab.

[0022] The above-mentioned current collector plate includes a main body that is electrically connected to the electrode tab.

[0023] The above main body part may include an electrode tab connecting part that is connected to the electrode tab.

[0024] The connection between the electrode tab connection portion and the electrode tab can be achieved by welding, brazing, or soldering. Preferably, the connection can be achieved by laser welding, which irradiates a laser onto the surface of the electrode tab connection portion.

[0025] The above main body part may include an inner part connected to the electrode tab connection part on the radially inner side of the electrode tab connection part.

[0026] The above-mentioned collector plate includes a can connection portion that is electrically connected to at least one of the side wall member and the cap.

[0027] The above can connection portion and the above main body portion can be electrically connected.

[0028] The above can connection part may be positioned radially outside the above main body part.

[0029] The above-mentioned collector plate includes a bridge extending radially, the radially inner side of which is connected to the main body portion, the radially outer side of which is connected to the can connection portion.

[0030] The above bridge includes, in order from the radially inner side to the outer side, a first bend portion, an offset bridge portion, and a second bend portion.

[0031] The above first bending portion is bent so that the extension direction of the bridge portion extending radially outward faces axially outward.

[0032] The offset bridge portion is connected radially inwardly to the first bend portion and radially outwardly to the second bend portion.

[0033] The above second bending portion is bent so that the extension direction of the bridge portion extending axially outward faces radially outward.

[0034] The above body part may be positioned axially further inward than the can connection part. That is, the can connection part may be positioned axially further outward than the above body part.

[0035] Accordingly, the axial distance between the can connection and the electrode assembly can be further secured.

[0036] The above bridge may further include an inner bridge portion having a radially inner side connected to the main body portion and a radially outer side connected to the first bend portion.

[0037] The above bridge may further include an outer bridge portion having a radially inner side connected to the second bending portion and a radially outer side connected to the can connecting portion.

[0038] The inner bridge portion may be arranged axially further inward than the outer bridge portion. That is, the outer bridge portion may be arranged axially further outward than the inner bridge portion.

[0039] The angle formed by the extension direction of the outer bridge portion with the radial direction may be 10 degrees or less. Preferably, the extension direction of the outer bridge portion may be parallel to the radial direction.

[0040] Accordingly, the axial distance between the can connection part and the outer bridge part and the electrode assembly can be further secured.

[0041] The bending angle of the first bending portion may be an acute angle.

[0042] The above offset bridge portion can extend axially outward as it extends radially outward. That is, the above offset bridge portion can extend obliquely.

[0043] The degree to which the above offset bridge portion is inclined with respect to the axial direction may be 0 degrees or more and less than 90 degrees.

[0044] The bending angle of the above second bending portion may be an acute angle.

[0045] The difference between the bending angle of the first bending portion and the bending angle of the second bending portion may be 10 degrees or less. Accordingly, the space occupied by the inner bridge portion and the outer bridge portion in the axial direction can be minimized.

[0046] The can connection portion may include an axial extension extending axially from the radially outer end.

[0047] The can connection portion may include a radial extension portion extending radially.

[0048]

[0049] The above axial extension portion can be connected to the above radial extension portion through a bend portion.

[0050] The above-mentioned bending portion can bend the radially extending portion that extends radially outward axially.

[0051] The axial extension of the above can connection portion can extend axially outward from the above bend portion.

[0052] The above can connection part may have a mating outer surface defined by the outer surface of the can connection part.

[0053] The above outer surface of the mating member can be defined by the outer surface of the axial extension.

[0054] The above-mentioned outer surface may face the inner surface of the side wall member in the radial direction.

[0055] At least a portion of the outer surface of the abutting member in the axial direction can define a first section that contacts the inner surface of the side wall member in the radial direction.

[0056] The above can connection portion may have a cap mating surface defined by an axial outer end surface.

[0057] The above cap mating surface can be defined by the end face of the axial extension portion.

[0058] The above cap mating surface can be in contact with the inner surface of the cap in the axial direction.

[0059] The above cap may include a joint outer surface facing the inner surface of the side wall member in the radial direction.

[0060] The above-mentioned outer surface of the joint can be in contact with the inner surface of the side wall member in the radial direction.

[0061] The above cap may have a collector plate mating surface defined by an axial inner surface.

[0062] The abutting surface of the above-mentioned collector plate can be in contact with the cap abutting surface of the can connection part of the above-mentioned collector plate in the axial direction.

[0063] The outer surface of the above cap may be positioned axially outside the contact surface of the collector plate.

[0064] The outer surface of the above cap may be positioned radially outside the contact surface of the collector plate.

[0065] The cap may have a pressing surface that contacts the collector plate and presses the collector plate radially outward. Accordingly, the collector plate may be brought into close contact with the inner surface of the side wall member in the radial direction.

[0066] At least a portion of the inner surface of the side wall member and at least a portion of the outer surface of the current collector plate can be joined.

[0067] At least a portion of the inner surface of the side wall member and at least a portion of the joint outer surface of the cap can be joined. Preferably, the joint outer surface of the cap can be entirely joined to the inner surface of the side wall member.

[0068] At least a portion of the cap mating surface of the above collector plate and at least a portion of the collector plate mating surface of the cap can be joined.

[0069] The above joint can be made by welding.

[0070] The above side wall member, the cap and the collector plate can be triple-welded together.

[0071] The above triple welding can be performed by welding together at least a portion of the side wall member, at least a portion of the cap, and at least a portion of the can connection portion of the current collector plate.

[0072] The above welding can be performed by a laser irradiating the abutting portion of the inner surface of the side wall member and the outer surface of the cap in the axial direction.

[0073] At least a portion of the inner surface of the side wall member, at least a portion of the joint outer surface of the cap, and at least a portion of the can connection portion of the current collector plate can be welded together and joined.

[0074] The outer diameter of at least a portion of the outer circumferential surface facing the axial direction may be larger than the inner diameter of the inner circumferential surface of the side wall member facing the section in the radial direction.

[0075] The outer diameter of the first section of the abutting outer surface may be larger than the inner diameter of the inner surface of the side wall member facing it in the radial direction. Accordingly, when the collector plate is inserted into the can, the first section of the abutting outer surface of the collector plate may be forcibly pressed into the side wall member.

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

[0077] The outer surface of the joint of the above cap and the outer surface of the mating portion of the above can connection can each face the inner surface of the side wall member in the radial direction.

[0078] The outer surface of the cap and the outer surface of the can connection portion can each be in contact with the inner surface of the side wall member in the radial direction.

[0079] The axial ends of the outer surface of the cap and the inner surface of the side wall member, which are radially facing or abutting each other, can be exposed axially outward.

[0080] The above welded portion can be formed by a laser radiating axially toward the axial ends of the outer surface of the cap and the inner surface of the side wall member from the axial outer side of the battery cell.

[0081] According to the present invention, since the first section of the outer surface of the current collector plate, which is positioned axially inner than the cap, faces and comes into contact with the inner surface of the side wall member, the laser can be prevented from being directly irradiated into the internal space of the can.

[0082]

[0083] The above-mentioned current collector plate may have a higher thermal conductivity than the side wall member. Accordingly, the welding heat is quickly distributed to the electrode assembly through the current collector plate, thereby preventing the welding heat from being transmitted to the outer surface of the electrode assembly through the side wall member, thereby damaging the separator provided on the outer surface of the electrode assembly.

[0084] In the bridge connecting the main body of the above-mentioned collector plate and the can connection portion, a portion positioned close to the can connection portion is axially spaced from the electrode assembly. In addition, the can connection portion is also axially spaced from the electrode assembly.

[0085] Accordingly, when welding is performed, the current collector plate, which is relatively hotter as it moves from the main body to the can connection, is made to have the can connection and outer bridge portions further apart in the axial direction from the electrode assembly, thereby preventing the electrode assembly from being damaged due to the high temperature of the welding heat.

[0086] An inner diameter expansion portion may be provided at one axial end of the above side wall member.

[0087] The first inner surface of the side wall member provided axially inward from the inner diameter expansion portion may have an inner diameter smaller than the second inner surface of the side wall member provided axially outward from the inner diameter expansion portion.

[0088] The above inner diameter expansion portion may have a shape that expands the inner diameter of the side wall member as it goes outward in the axial direction.

[0089] The above inner diameter expansion portion may include an inclined surface shape provided on the inner surface of the side wall member and extending radially outward as it goes axially outward.

[0090] The above inner diameter expansion portion can prevent internal penetration of laser that may enter through the gap between the side wall member and the cap or collector plate.

[0091] At least a portion of the first section of the above-mentioned outer surface in the axial direction can be in contact with the above-mentioned first inner surface.

[0092] At least a portion of the first section of the outer circumferential surface facing in the axial direction may also be in contact with the inner diameter expansion portion.

[0093] At least a portion of the first section of the above-mentioned outer circumferential surface in the axial direction can also be in contact with the second outer circumferential surface.

[0094] The outer diameter of the first section of the above-mentioned outer surface may be larger than the inner diameter of the above-mentioned first inner surface.

[0095] The outer diameter of the mating outer surface of the can connection portion of the above-mentioned collector plate may be larger than the inner diameter of the first inner surface.

[0096] The material of the above-mentioned collector plate may be softer than the material of the above-mentioned side wall member.

[0097] When the outer diameter of the above-mentioned outer circumference is set slightly larger than the inner diameter of the first inner circumference, the above-mentioned outer circumference is pressed into the above-mentioned first inner circumference during the process of inserting the collector plate, so that the above-mentioned outer circumference and the above-mentioned first inner circumference can be brought into close contact in the radial direction.

[0098] As a result, with the collector plate inserted, the outer diameter of the first section of the abutting outer surface in contact with the first inner surface can correspond to the inner diameter of the first inner surface.

[0099] By means of the above-mentioned bending portion, a curved surface whose outer diameter gradually decreases as it goes axially inward can be provided axially inwardly from the above-mentioned cap connecting portion.

[0100] The minimum outer diameter of the above-mentioned curved surface may be smaller than the inner diameter of the first inner surface.

[0101] Accordingly, in the process of inserting the collector plate, forced pressing of the cap connection part to the first inner surface can be guided.

[0102] The first inner surface of the side wall member into which the first section of the outer surface of the mating member is forcibly pressed may be arranged closer to the bend portion in the axial direction than the second inner surface of the side wall member.

[0103] The outer surface of the above cap may face the second inner surface in the radial direction.

[0104] The mating outer surface of the above can connection part can face the second inner surface in the radial direction from an axial direction further inward than the above joining outer surface.

[0105] The outer surface of the joint of the above cap and the outer surface of the can connection of the above collector plate can each be in contact with the second inner surface.

[0106] The outer diameter of the above-mentioned outer surface may correspond to or be smaller than the inner diameter of the above-mentioned second inner surface.

[0107] The above cap may be provided with a cap body, a thickness reduction portion, and a joint portion in that order from the radial center outward.

[0108] In other words, the thickness reduction portion may be provided on the radially outer side of the cap body, and the joint portion may be provided on the radially outer side of the thickness reduction portion.

[0109] The outer surface of the joint of the above cap can be provided at the joint.

[0110] The above first thickness may be a thickness of the joint measured in the axial direction.

[0111] The above first thickness may be smaller than the second thickness of the cap body measured in the axial direction.

[0112] By increasing the second thickness of the cap body, which occupies the overall shape of the cap, the deformation of the cap due to the internal pressure of the can is minimized, while the axial dimension of the welding portion for the side wall member, i.e. the outer circumferential surface of the joint, is suppressed so that the welding portion is formed over the entire axial direction of the outer circumferential surface of the joint, thereby increasing both the strength of the cap itself and the bonding strength of the cap to the side wall member.

[0113] The above thickness reduction portion may be provided on the axial inner surface of the cap.

[0114] By appropriately selecting the position where the thickness reduction portion is provided so that at least a part of the thickness reduction portion can contact the collector plate, the effect of the thickness reduction portion of the cap being in contact with the collector plate and the center of the cap being aligned can be enjoyed during the process of inserting the cap.

[0115] To enhance this alignment effect, the thickness reduction portion may include a sloped surface shape that extends axially outward as it goes radially outward.

[0116] The above thickness reduction portion and joint portion can be formed by forging.

[0117] As the above cap is inserted, the radially inner edge of the axial outer end of the cap connection portion of the above collector plate can come into contact with the inclined surface of the thickness reduction portion.

[0118] Accordingly, the center of the cap and the center of the collector plate can be aligned, and also, the axial outer end of the cap connection portion of the collector plate can be pressed radially outward to come closer to or adhere closely to the second inner surface of the side wall member.

[0119] The pressurized surface of the above cap can be implemented by the inclined surface.

[0120]

[0121] The present invention provides a method for manufacturing the above-described battery cell.

[0122] The battery cell may include 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 inside the can.

[0123] The method for manufacturing such a battery cell includes a first step of joining a current collector to an electrode tab provided at an end corresponding to the open end among the axial ends of the electrode assembly.

[0124] The above manufacturing method includes a second step of inserting the current collector into the can and contacting a first section, which is at least an axial portion of the outer surface of the abutting can connection provided on the radial outer edge of the current collector, with the inner surface of the side wall member.

[0125] At this time, the can connection part of the collector plate is forcibly pressed into the first inner surface which is positioned axially further inward than the inner diameter expansion part of the side wall member, thereby increasing the adhesion between the first inner surface and the joint outer surface of the collector plate.

[0126] The above manufacturing method includes a third step of covering the open end of the side wall member with a cap and contacting a radially outer edge of the cap with at least one of the side wall member and the can connecting portion of the current collector plate.

[0127] Specifically, in the third step, the outer surface of the joint provided on the edge of the cap and the abutting surface of the collector plate can be brought into contact with the inner surface of the side wall member and the cap abutting surface of the collector plate, respectively.

[0128] At this time, the thickness reduction portion in the form of an inclined surface provided on the axial inner surface of the cap may be brought into contact with the current collector plate to align the center of the cap (or), and the axial outer end of the cap-fitting surface of the current collector plate may be pressed radially outward to bring it closer to the second inner surface of the side wall member or to make close contact therewith.

[0129] The above manufacturing method includes a fourth step of welding together the side wall member, the cap, and the can connection portion of the current collector plate by irradiating a laser to the side wall member, the cap, and the can connection portion of the current collector plate.

[0130] Specifically, in the fourth step, a laser is irradiated from the axial outer side to the axial outer side to the abutting portion of the inner surface of the side wall member and the joint outer surface of the cap, so that the inner surface of the side wall member, the joint outer surface of the cap, and the can connection portion of the current collector can be welded together.

[0131] According to the present invention, through the radial elastic structure of the bridge having the first bending portion and the second bending portion, the assembly of the can, the collector plate, and the cap is easy, and during the assembly process, the mutually abutting structure enables correct position alignment and close contact, and even if there is a dimensional tolerance of the parts, deformation of the parts is suppressed during the assembly process, and accurate assembly is possible.

[0132] According to the present invention, the geometric structure of the bridge having the first bend and the second bend allows the can connection of the current collector plate to be spaced apart from the electrode assembly in the axial direction, thereby minimizing the influence of heat generated during the welding process of the can and the cap on components inside the battery cell, thereby further securing the axial volume of the electrode assembly, thereby increasing the energy density of the battery cell.

[0133] According to the present invention, through a forced pressing structure of the outer surface of the collector plate against the inner surface of the side wall member, alignment of the side wall member and the collector plate and adhesion of the welding portion between the side wall member and the collector plate are secured, and by the adhesion portion, a laser irradiated in the axial direction for welding can be prevented from being irradiated into the inside of the can.

[0134] According to the present invention, the cap connection portion of the current collector plate is formed to be long in the axial direction, so that even if a portion of the laser irradiated in the axial direction for welding penetrates into the gap between the cap connection portion and the side wall member, the laser can be prevented from being directly irradiated to the internal space of the can.

[0135] According to the present invention, by forming an inner diameter extension portion on the inner surface of a side wall member to provide a first inner diameter portion and a second inner diameter portion having different inner diameters, and forcibly pressing a cap connection portion of a collector plate into a section of the first inner diameter portion that is positioned further inward in the axial direction and has a smaller inner diameter, the pressing force required during assembly can be lowered while the pressing force between the collector plate and the side wall member can be concentrated on the corresponding section, thereby ensuring close contact between them.

[0136] According to the present invention, the inner diameter expansion portion of the side wall member functions as a barrier that blocks laser penetration radiated in the axial direction for welding, thereby reliably preventing the laser from being radiated directly into the inside of the can.

[0137] According to the present invention, a section of the axial section of the cap connection part close to the bending section is forcibly pressed into the first inner diameter section, thereby further securing radial support force of the bending section and the electrode tab connection section for the forced pressing section.

[0138] According to the present invention, the curved surface provided by the bending portion of the collector plate guides the forced pressing of the collector plate during the insertion process of the collector plate into the side wall member, thereby increasing the convenience of assembly.

[0139] According to the present invention, since the cap is inserted to a position where the axial inner surface of the cap contacts the axial outer end of the cap connection portion of the collector plate, the insertion depth of the cap can be regulated through the axial extension length of the cap connection portion, thereby increasing assembly accuracy.

[0140] According to the present invention, in the process of inserting the cap, the inclined surface provided in the thickness reduction portion of the cap comes into contact with the cap connection portion of the current collector plate, and the center of the cap can be aligned with respect to the center of the current collector plate, thereby increasing the convenience of assembly.

[0141] According to the present invention, when the cap is inserted, the axial outer end of the cap connection portion of the current collector plate can be pressed radially outward by the inclined surface of the thickness reduction portion of the cap, thereby allowing the axial outer end of the cap connection portion to come closer to, contact, or adhere to the second inner surface of the side wall member. Accordingly, the adhesion of the welding portion can be enhanced.

[0142] According to the present invention, weldability can be secured so that the side wall member, the cap, and the collector plate can be welded together.

[0143] According to the present invention, process stability can be secured by welding the side wall member, the cap, and the collector plate together.

[0144] According to the present invention, the assembly work of a battery cell can be significantly reduced by welding the side wall member, the cap, and the collector plate together.

[0145] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0146] Figure 1 is a perspective view of a cylindrical battery cell of an embodiment.

[0147] Figure 2 is an exploded perspective view of the electrode assembly accommodated inside the can of Figure 1 before winding.

[0148] Fig. 3 is a perspective view of the electrode assembly of Fig. 2 in a pre-winding laminated state.

[0149] Fig. 4 is a perspective view of an assembled cylindrical jelly-roll-shaped electrode assembly by winding up the laminate of Fig. 3.

[0150] Figure 5 is a perspective view showing a state in which a first collector plate is joined to an electrode tab of a first electrode of an electrode assembly.

[0151] Figure 6 is a perspective view showing a state in which a second collector plate is joined to an electrode tab of a second electrode of an electrode assembly.

[0152] Figure 7 is a perspective view of the second collector plate of Figure 6.

[0153] Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7.

[0154] Figure 9 is a cross-sectional view taken along line 9-9 of Figure 7.

[0155] Fig. 10 is a perspective view showing a portion of the cross-section of Fig. 8.

[0156] Figure 11 is a side cross-sectional view showing the process of accommodating an electrode assembly with a current collector plate bonded thereto inside a can.

[0157] Figure 12 is a side cross-sectional view showing the bonding process of the first collector plate and the first electrode terminal of the electrode assembly accommodated in the can.

[0158] Figure 13 is a side cross-sectional view showing the process of covering the open end of the can containing the electrode assembly with a cap.

[0159] Figures 14 and 15 are side cross-sectional views showing the process of closing the filling port of a cap that is joined to the side wall member of the can and has its open end closed with a stopper.

[0160] Fig. 16 is a cross-sectional view showing an enlarged area of ​​the open end portion of the battery cell of Fig. 15, where a dotted line is indicated, and is a drawing expressing the state of the process of inserting a cap while the electrode assembly is accommodated inside the can and the current collector is inserted.

[0161] Figure 17 is a drawing showing the state in which the cap is inserted in Figure 16.

[0162] Figure 18 is an enlarged view of the abutment portion of the side wall member, the collector plate, and the cap in Figure 17.

[0163] Figure 19 is a drawing showing a state in which a welded portion is formed by welding the side wall member, the collector plate, and the cap portion in Figure 17.

[0164] FIG. 20 and FIG. 21 are flowcharts of a battery cell manufacturing process according to the present invention. FIG. 20 is a flowchart of a battery cell manufacturing process using a cap having a liquid filler port, and FIG. 21 is a flowchart of a battery cell manufacturing process using a cap without a liquid filler port.

[0165] Figures 22 and 23 illustrate a battery pack to which the battery cell of the embodiment is applied and a vehicle equipped with such a battery pack.

[0166] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0167] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0168] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0169] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0170] Additionally, when it is described that a component is "connected," "coupled," or "in contact with" another component, it should be understood that the components may be directly connected or in contact with each other, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "in contact with" another component.

[0171] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0172] Throughout the specification, when we refer to "A and / or B", this means A, B, or A and B, unless otherwise stated, and when we refer to "C through D", this means C or more and D or less, unless otherwise stated.

[0173] In describing the embodiment, the axial direction refers to the direction in which the axis forming the winding center of the jelly-roll type electrode assembly extends, the radial direction refers to the direction approaching (centripetal) or moving away (centrifugal) from the axis, and the circumferential direction refers to the direction surrounding the axis.

[0174] Hereinafter, with reference to FIGS. 1 to 17, an embodiment of a battery cell to which the welding structure of the present invention is applied will be described in detail.

[0175] The battery cell of the embodiment may be, for example, a cylindrical battery cell having a form factor ratio (defined as the ratio of the diameter (Φ) to the height (H) of a cylindrical battery cell) of greater than about 0.4.

[0176] Here, the form factor refers to a value indicating the diameter and height of a cylindrical battery cell. The cylindrical battery cell may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two numbers indicate the diameter of the cell, the next two numbers indicate the height of the cell, and the last number 0 indicates that the cross-section of the cell is circular.

[0177] The above battery cell may be a cylindrical battery cell having a roughly cylindrical shape, a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0178] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0179] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0180] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0181] According to another embodiment, a battery cell may be a cylindrical battery cell having a generally cylindrical shape, a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0182] The present invention can of course also be applied to battery cells having a form factor ratio of approximately 0.4 or less, such as 18650 cells, 21700 cells, etc. For 18650 cells, the diameter is approximately 18 mm, the height is approximately 65 mm, and the form factor ratio is 0.277. For 21700 cells, the diameter is approximately 21 mm, the height is approximately 70 mm, and the form factor ratio is 0.300.

[0183] The battery cell of the embodiment includes an electrode assembly (20), a current collector (31, 32) electrically connected to the electrode assembly (20), and a can (10) that accommodates the electrode assembly (20) and the current collector (31, 32).

[0184] The above can (10) includes a bottom member (12), a side wall member (11) connected to the bottom member (12) and extending in the axial direction, and an open end provided at one axial end of the side wall member (11).

[0185] The above can (10) includes a cap (16) covering the open end.

[0186] The above-mentioned floor member (12) has a disc shape with a hole formed in the center, and the side wall member (11) may have a circular tube shape.

[0187] The above-mentioned bottom member (12) and side wall member (11) can be manufactured by forming a metal sheet with a nickel plated surface using a deep drawing process, and trimming the front end of the side wall member (11) with a punch while holding it with a blank holder. Of course, the material of the can (10) is not limited to this.

[0188] A first electrode terminal (13) can be fitted into the hole. The first electrode terminal (13) can be fixed by riveting to the bottom member (12) with a gasket (14) interposed therebetween. The gasket (14) is interposed between the first electrode terminal (13) and the bottom member (12), sealing the inside and outside of the can (10) to prevent leakage of the electrolyte, and electrically insulating the first electrode terminal (13) and the bottom member (12).

[0189] However, the method of connecting the first electrode terminal (13) and the bottom member (12) is not limited to this. For example, if there is a structure that can seal 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 joint method, a glass seal method, or a chrome coating & PP-MAH thermal bonding method, can also be applied.

[0190] The first electrode terminal (13) above may have a first polarity, and the can (10) may have a second polarity. That is, the bottom member (12) of the can (10), the side wall member (11) connected thereto, and the cap (16) connected to the side wall member (11), which will be described later, may all have a second polarity.

[0191] Accordingly, the battery cell may have both the first electrode terminal (13) and the second electrode terminal (15) positioned at the axial end, i.e., the closed end, provided with the bottom member (12). Then, the battery cell may have both the bus bar connected to the first electrode terminal (13) and the bus bar connected to the second electrode terminal (15) positioned at the upper portion of the battery cell.

[0192] 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.

[0193] An electrode assembly (20) is accommodated within the can (10). The electrode assembly (20) is prepared by preparing a first electrode (21), a second electrode (22), and a separator (28) having a predetermined width and extending in the longitudinal direction as illustrated in FIG. 2, and forming a laminated body by sequentially stacking the first electrode (21), the separator (28), the second electrode (22), and the separator (28) as illustrated in FIG. 3, and then winding this around a core shaft as illustrated in FIG. 4, in the form of a jelly-roll.

[0194] The above first electrode (21) may be an anode, and the above second electrode (22) may be a cathode. Of course, the opposite may also be the case.

[0195] The above first electrode (21) and second electrode (22) are manufactured in the form of sheets. The electrode sheet is manufactured in the form of an active material layer (24) applied to the surface of a metal foil (23). The electrode sheet has a holding portion (25) region where the active material layer (24) is applied, and a non-coated portion (26) region where the active material layer (24) is not applied. The positive electrode sheet has a non-coated portion (26) region on one side in the width direction, and the negative electrode sheet has a non-coated portion (26) region on the other side in the width direction.

[0196] The non-conductive portion (26) is exposed or protrudes in the width direction of the laminate. The non-conductive portion (26) itself functions as an electrode tab (27).

[0197] In the above-mentioned blank portion (26), notches can be formed at a predetermined interval to form flag-shaped notching tabs (27).

[0198] In the embodiment, the notching tabs (27) are exemplified as having an equilateral trapezoidal shape. However, their shapes may be various, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0199] In addition, in the embodiment, a form in which the notching tabs (27) arranged along the longitudinal direction have the same width is exemplified. However, the width of the notching tabs may be gradually or stepwise widened from the core side to the outer periphery side.

[0200] In addition, in the embodiment, a form in which the height of the notching tabs (27) gradually increases from the core side to the outer circumference side is exemplified. However, the height of these notching tabs may be implemented in a form in which they are constant or gradually decrease.

[0201] In addition, in the embodiment, a structure is exemplified in which a notching tab (27) is deleted in a predetermined section of the centrifugal end of the non-conductive portion (26) and a predetermined section of the centrifugal end. However, it is of course possible that the notching tab may not be deleted in the centrifugal end of the non-conductive portion, and that the notching tab may not be deleted in the centrifugal end of the non-conductive portion.

[0202] In the jelly roll-shaped electrode assembly (20), the notched tab (27) can be bent radially and flattened as illustrated in FIG. 4. The notched tab (27) can be bent radially inward or outward. In the embodiment, a structure in which the notched tab (27) is bent radially inward is exemplified.

[0203] The above-mentioned notched tabs (27) can be bent one by one during the process of forming a jelly roll-shaped electrode assembly (20) by winding the laminate. Alternatively, the above-mentioned notched tabs (27) can be bent all at once after the laminate is wound to form a jelly roll-shaped electrode assembly.

[0204] The notching tabs (27) of the first electrode (21) and the notching tabs (27) of the second electrode (22), which are folded and overlapped in the radial direction, can provide a plane that is substantially perpendicular to the axial direction at each of the axial ends of the electrode assembly (20).

[0205] As shown in FIGS. 5 and 6, the first collector plate (31) and the second collector plate (32) can be joined to a substantially flat surface provided by bending the notched tabs (27) exposed at both axial ends of the electrode assembly (20).

[0206] In the embodiment, the first collector plate (31) is exemplified as a positive collector plate and the second collector plate (32) is exemplified as a negative collector plate. The first collector plate (31) may be made of aluminum, and the second collector plate (32) may be made of copper.

[0207] The above-mentioned collector plate (31, 32) can be manufactured by punching, trimming, piercing, and bending a metal sheet.

[0208] Referring to Fig. 5, the first collector plate (31) has a terminal connection portion (312) extending radially from the center, a ring portion (313) connecting the centrifugal edge of the terminal connection portion (312) in a circumferential direction, and an electrode connection portion (314) extending centripetally from the ring portion (313) but not connected to the terminal connection portion (312). The center portion of the terminal connection portion (312) covers at least a portion of the core hollow portion of the electrode assembly (20).

[0209] The above electrode connection part (314) is joined to the notched tab (27) of the first electrode (21) of the electrode assembly (20) by laser welding or the like before the electrode assembly (20) is placed in the can (10). The welding line of the laser may extend radially.

[0210] Referring to FIGS. 6 to 10, the second collector plate (32) includes a main body portion (320) connected to the electrode tab (27) of the electrode assembly (20) and an outer ring-shaped can connection portion (324) disposed radially outside the main body portion (320) and surrounding the edge of the second collector plate (32). The can connection portion (324) is disposed radially apart from the main body portion (320).

[0211] The second collector plate (32) includes a bridge (33) whose radially inner side is connected to the main body (320) and whose radially outer side is connected to the can connection part (324).

[0212] The main body (320) includes an inner ring (321) that defines a hole (322) corresponding to the core hollow portion of the electrode assembly (20) and is provided in a form that surrounds the core hollow portion, and an electrode tab connection portion (323) that extends radially from the inner ring portion (321). The main body (320) can be electrically connected to the electrode tab (27) of the electrode assembly (20) by welding with a laser irradiated onto the electrode tab connection portion (323).

[0213] The above electrode tab connection portion (323) can be joined to the notched tab (27) of the second electrode (22) of the electrode assembly (20) by laser welding or the like before placing the electrode assembly (20) into the can (10). The welding line of the laser can extend radially.

[0214] The above can connection part (324) is electrically connected to the main body part (320) through the bridge (33) extending in the radial direction.

[0215] The above can connection part (324) has a radial extension part (3242) extending in the radial direction, a bend part (327) provided at the centrifugal end of the radial extension part (3242), and an axial extension part (3241) extending axially outward from the bend part (327).

[0216] The above bridge (33) can be arranged alternately with the electrode tab connection portion (323) in the circumferential direction. The above bridge (33) can be connected to the inner ring portion (321).

[0217] The above bridge (33) includes an inner bridge portion (333) that is connected radially inwardly to the main body portion (320) and extends radially outwardly from the main body portion (320). A first bend portion (331) is provided at the radially outward end of the inner bridge portion (333) so that the extension direction of the inner bridge portion (333) extending radially outwardly faces the axial outward.

[0218] The above bridge (33) includes an outer bridge portion (335) that is connected radially outer to the can connection portion (324) and extends radially inward from the can connection portion (324). A second bend portion (332) is provided at the radially inner end of the outer bridge portion (335) so that the extension direction of the outer bridge portion (335) extending radially inward faces axially inward.

[0219] Between the first bend portion (331) and the second bend portion (332), an offset bridge portion (334) is provided, the radially inner side of which is connected to the first bend portion (331) and the radially outer side of which is connected to the second bend portion (332). The offset bridge portion (334) extends axially outward as it extends radially outward. Accordingly, the second bend portion (332) is arranged radially further outward and axially further outward than the first bend portion (331).

[0220] The bending angle (b1) of the first bending portion may be an acute angle, and the bending angle (b2) of the second bending portion may be an acute angle. The difference between the two bending angles may be 10 degrees or less.

[0221] The above inner bridge portion (333) can extend substantially parallel to the radial direction.

[0222] The angle formed by the extension direction of the outer bridge portion (335) with the radial direction may be 10 degrees or less. Preferably, the outer bridge portion (335) may extend substantially parallel to the radial direction.

[0223] By means of the first bending portion (331), the can connection portion (324), the outer bridge portion (335), and the offset bridge portion (334) can be arranged axially further outward than the inner bridge portion (333) and the main body portion (320).

[0224] By means of the second bending portion (332), the can connection portion (324) and the outer bridge portion (335) can be positioned further outward in the axial direction than the inner bridge portion (333) and the main body portion (320).

[0225] In this way, the bridge (33) of the second collector plate (32) of the present invention can be provided with an offset bridge portion (334), whereby the outer bridge portion (335), which is positioned further outward than the inner bridge portion (333) in the radial direction, can be spaced upward from the electrode assembly (20). Therefore, in the case where the can connection portion (324) and the can (10) are joined by a thermal bonding method such as welding, for example, even if a large amount of heat is transferred to the inner bridge portion (333), which is positioned relatively closer from the can connection portion (324) than the outer bridge portion (335), the risk of damage to the electrode assembly (20) due to such heat can be greatly reduced.

[0226] By means of the first bending portion (331) and the second bending portion (332), the bridge (33) can be easily elastically deformed in the radial direction.

[0227] As illustrated in FIGS. 11 and 12, the electrode assembly (20) is accommodated in the can (10) in a state where the first collector plate (31) is aligned toward the bottom member (12) of the can (10). At this time, an insulator (19) is interposed between the first collector plate (31) and the bottom member (12) of the can (10) to electrically insulate the first collector plate (31) and the bottom member (12).

[0228] And, the terminal connection part (312) of the first collector plate (31) is joined to the first electrode terminal (13) fixed to the can (10) by resistance welding, ultrasonic welding, laser welding, or the like. The welding device for welding the first collector plate (31) and the first electrode terminal (13) can approach the back surface of the center of the terminal connection part (312) of the first collector plate (31) through the core hollow part of the electrode assembly (20) from the open end of the can (10) and perform welding. Of course, in addition to this, the first collector plate (31) and the first electrode terminal (13) can also be joined by brazing or soldering. In other words, various methods can be applied to the first collector plate (31) and the first electrode terminal (13) as long as they are a joining method that can electrically connect them and fix them to each other.

[0229] With the electrode assembly (20) housed inside the can (10), the electrode tab (27) of the second electrode (22) and the second collector plate (32) are positioned to face the open end of the side wall member (11). In addition, the outer circumferential surface of the second collector plate (32) is in contact with the inner circumferential surface of the side wall member (11) and is pressed into it.

[0230] As shown in FIG. 6, when the second collector plate (32) is joined to the electrode assembly (20), if the center of the second collector plate (32) is not exactly aligned with the center of the electrode assembly (20), as shown in FIG. 11, the inner surface of the can (10) and the outer surface of the second collector plate (32) may not be concentrically aligned during the process of inserting the electrode assembly (20) into the can (10) in the axial direction.

[0231] In addition, even if the center of the second collector plate (32) is precisely aligned with the center of the electrode assembly (20), if the center of the can (10) and the center of the electrode assembly (20) are not aligned during the process of inserting the electrode assembly (20) into the can (10) in the axial direction as shown in FIG. 11, the inner surface of the can (10) and the outer surface of the second collector plate (32) may not be concentrically aligned.

[0232] At this time, if the second collector plate (32) is a rigid body that does not elastically deform, the external force generated by the eccentricity of the inner surface of the can (10) and the outer surface of the second collector plate (32) applies a load to the welding area of ​​the second collector plate (32) and the electrode tab (27) of the electrode assembly (20).

[0233] On the other hand, if the bridge (33) has a first bend portion (331) and a second bend portion (332) such as the second collector plate (32) of the present invention so that elastic deformation in the radial direction can be easily achieved, even if the outer surface of the second collector plate (32) is eccentric with the inner surface of the can (10), most of the load generated by this is absorbed by the elastic deformation of the bridge (33), and almost no load is applied to the welding portion of the second collector plate (32) and the electrode tab (27) of the electrode assembly (20).

[0234] In this way, the first bend (331) and the second bend (332) of the above bridge (33) protect the welding area between the second collector plate (32) and the electrode assembly (20) during the process of pressing the second collector plate (32) into the can (10).

[0235] After the first collector plate (31) and the first electrode terminal (13) are joined, the open end of the side wall member (11) is covered by a cap (16) as shown in FIGS. 13 and 14 and finished through seam welding or the like. Then, an electrolyte can be injected into the can (10) through the injection port (18) provided in the center of the cap (16).

[0236] After injecting the electrolyte, as shown in FIGS. 14 and 15, the injection port (18) can be closed by a stopper (40).

[0237] Of course, the welding structure of the present invention can also be applied to a cap without a liquid injection port. Accordingly, before covering the open end of the side wall member (11) with the cap (16), the electrolyte can be injected first, and after the electrolyte injection is complete, the open end can be covered with the cap (16) for final closure.

[0238] The edge of the cap (16) is joined by laser welding with the edge of the side wall member (11) as shown in Fig. 18, and thus the can (10) can be sealed.

[0239] Referring to FIGS. 16 and 17, the side wall member (11) has an inner diameter expansion portion (113) on the open end side. The inner diameter expansion portion (113) has an inclined surface shape provided on the inner surface of the side wall member (11) so as to expand the inner diameter of the side wall member (11) as it goes outward in the axial direction. That is, the inner diameter expansion portion (113) includes an inclined surface shape provided on the inner surface of the side wall member (11) and extending radially outward as it goes outward in the axial direction.

[0240] Accordingly, the inner surface of the side wall member (11) may include a first inner surface (111) provided axially inwardly than the inner diameter expansion portion (113), and a second inner surface (115) provided axially outwardly than the inner diameter expansion portion (113).

[0241] The outer circumferential surface of the side wall member (11) may have a uniform diameter along the axial direction, while the second inner circumferential surface (115) may have an inner diameter greater than that of the first inner circumferential surface (111). Accordingly, the side wall member (11) may have a thickness measured in the radial direction at a portion where the second inner circumferential surface (115) is provided that is smaller than a thickness measured in the radial direction at a portion where the first inner circumferential surface (111) is provided.

[0242] The can connection portion (324) provided at the edge of the second collector plate (32) and electrically connected to the can (10) includes a first portion that faces or comes into contact with the inner surface (111, 113, 115) of the side wall member (11). The first portion is provided with an abutting outer surface (325) that faces or comes into contact with the inner surface (111, 113, 115) of the side wall member (11) in the radial direction.

[0243] The above can connection portion (324) includes a second portion that comes into contact with the cap (16). The second portion is provided with a cap mating surface (326) that faces and comes into contact with the inner surface of the cap (16) in the axial direction.

[0244] The above first and second parts are provided in the axial extension (3241) of the can connection part (324).

[0245] The axial extension (3241) of the above can connection (324) is connected to the axial outer side of the above bending portion (327) and has a shape extending axially outward from the above bending portion (327). Accordingly, the area and axial length of the mating outer surface (325) of the second collector plate (32) can be further secured.

[0246] The material of the above second collector plate (32) may be softer than the material of the side wall member (11).

[0247] The thermal conductivity of the second collector plate (32) may be higher than the thermal conductivity of the side wall member (11).

[0248] For example, the material of the second collector plate (32) may include copper, and the material of the side wall member (11) may include iron.

[0249] The outer diameter of the mating outer surface (325) of the above can connection portion (324) is set to be larger than the inner diameter of the first inner surface (111). The outer diameter of the mating outer surface (325) may correspond to or be smaller than the inner diameter of the second inner surface (115).

[0250] Then, in the process of inserting the second collector plate (32), the bending portion (327) is elastically deformed and the abutting outer peripheral surface (325) is forcibly pressed into the first inner peripheral surface (111), so that the abutting outer peripheral surface (325) and the first inner peripheral surface (111) are in close contact in the radial direction. Accordingly, as a result, the outer diameter of the first section (a) of the abutting outer peripheral surface (325) pressed into the first inner peripheral surface (111) in the axial direction corresponds to the inner diameter of the first inner peripheral surface (111).

[0251] The radial extension (3242) of the can connection portion (324) supports the outer shape of the can connection portion (324) when the bend portion (327) is elastically deformed by receiving a force in the radial direction.

[0252] In this way, by the multi-stage inner surface structure of the side wall member (11) and the can connection part (324) structure of the collector plate (32), at least a portion of the axial direction of the abutting outer surface (325) is firmly adhered to the inner surface of the side wall member (11).

[0253] The above-mentioned bending portion (327) provides a curved surface whose outer diameter gradually decreases as it goes axially inward compared to the outer diameter of the axial extension portion (3241) of the can connection portion (324). In addition, the minimum outer diameter (d) of the curved surface measured from the lower end of the radial extension portion (3242) may be smaller than the inner diameter of the first inner peripheral surface (111). This shape guides the can connection portion (324) to be forcibly pressed into the first inner peripheral surface (111) during the process of inserting the second collector plate (32) into the inner space of the side wall member (11). Therefore, the process of forcibly pressing in the second collector plate (32) can be performed more easily.

[0254] Ultimately, according to the present invention, if only the dimensional relationship can be maintained so that the minimum outer diameter (d) of the bent portion (327) is smaller than the inner diameter of the first inner peripheral surface (111) of the side wall member (11), and the outer diameter of the bonding outer peripheral surface (171) of the second collector plate (32) is larger than the inner diameter of the first inner peripheral surface (111), despite the dimensional tolerance of the parts, the first section (a) of the abutting outer peripheral surface (325) is reliably brought into close contact with the first inner peripheral surface (111) of the side wall member (11). In addition, such dimensional control can be easily achieved. In addition, according to the present invention, despite the assembly error between the parts, the assembly error is absorbed by the first bent portion (331) and the second bent portion (332) of the bridge (33).

[0255] Accordingly, the present invention can reliably prevent the phenomenon of the laser (L) being directly irradiated into the inside of the can (10) by the can connection portion (324) of the second collector plate (32) extended in the axial direction, the forced fit portion (P) through forced pressing between the first inner peripheral surface (111) of the side wall member (11) and the first section (a) of the abutting outer peripheral surface (325) of the second collector plate (32), and the inner diameter expansion portion (113) of the side wall member (11), even if a part of the laser (L) penetrates inside as shown in FIG. 18 during the welding process described later.

[0256] The cap (16) is provided with a cap body (160), a thickness reduction portion (161), and a joint portion (17) in that order from the radial center to the outside. That is, the thickness reduction portion (161) is provided on the radial outside of the cap body (160), and the joint portion (17) is provided on the radial outside of the thickness reduction portion (161).

[0257] Accordingly, the first thickness (t1) of the joint (17) measured in the axial direction is smaller than the second thickness (t2) of the cap body (160) measured in the axial direction.

[0258] At the joint portion (17) of the cap (16), a joint outer circumferential surface (171) is provided that faces or comes into contact with the second inner circumferential surface (115) of the side wall member (11) in the radial direction. In addition, at the axial inner surface of the joint portion (17) of the cap (16), a collector plate mating surface (173) that faces and comes into contact with the cap mating surface (326) of the can connection portion (324) of the second collector plate (32) in the axial direction is provided.

[0259] The above thickness reduction portion (161) is a thickness change portion provided in the cap (16).

[0260] By appropriately selecting the position where the thickness reduction portion (161) is provided so that at least a part of the thickness reduction portion (161) can contact the second collector plate (32), the thickness reduction portion (161) of the cap (16) can come into contact with the second collector plate (32) during the process of inserting the cap (16), and the effect of the center of the cap (16) being aligned can be enjoyed.

[0261] In order to enhance the alignment effect, the embodiment implemented the thickness reduction portion (161) in the form of a slope that extends axially outward as it goes radially outward.

[0262] In the process of inserting the cap (16) into the side wall member (11), the thickness reduction portion (161) in the form of an inclined surface can come into contact with the radially inner edge of the cap abutment surface (326). Accordingly, the axial outer end of the can connection portion (324) of the second collector plate (32) provided with the cap abutment surface (326) is pressed radially outward by the thickness reduction portion (161), so that it can be arranged closer to or in closer contact with the second inner peripheral surface (115) of the side wall member (11).

[0263] That is, the thickness reduction portion (161) in the form of the inclined surface is brought into contact with the can connection portion (324) of the second collector plate (32) during the process of inserting the cap (16) into the open end of the side wall member (11), and can not only guide the center alignment of the cap (16) with respect to the center of the second collector plate (32), but also press the axial outer end of the can connection portion (324) of the second collector plate (32) radially outward to bring the axial outer end of the can connection portion (324) of the second collector plate (32) into close contact with the second inner surface (115) of the side wall member (11).

[0264] In a state where the cap (16) is inserted into the open end of the side wall member (11), the joint outer circumference (171) of the cap (16) and the mating outer circumference (325) of the second collector plate (32) face or contact very closely to the second inner circumference (115) of the side wall member (11) in the radial direction. In other words, the joint outer circumference (171) of the cap (16) can face or contact the second inner circumference (115) in the radial direction, and the mating outer circumference (325) of the can connection portion (324) can face or contact the second inner circumference (115) in the radial direction further inward than the joint outer circumference (171).

[0265] And, in the axial direction, the cap mating surface (326) provided on the axial outer end surface of the can connection portion (324) of the second collector plate (32) is in contact with the collector plate mating surface (173) provided on the inner surface of the joint portion (17) of the cap (16).

[0266] According to this assembly structure, the insertion depth of the cap (16) can be precisely regulated by the height (H) of the second collector plate (32), which can be influenced by the axial extension length of the can connecting portion (324).

[0267] Meanwhile, even if there is a slight error in the outer diameter of the joint outer circumference (171) of the cap (16), the inner diameter of the second inner circumference (115) of the side wall member (11), and the outer diameter of the mating outer circumference (325) of the second collector plate (32), so that the joint outer circumference (171) of the cap (16) and the mating outer circumference (325) of the second collector plate (32) do not come into close contact with the second inner circumference (115) of the side wall member (11), there is no concern at all that the laser (L) irradiated for welding will penetrate into the inside of the can (10) due to the structure of the forced fit portion (P) and the inner diameter expansion portion (113) as illustrated in FIG. 18.

[0268] In the above battery cell, a welded portion (W) is formed in which the second inner peripheral surface (115) portion of the side wall member (11), the joint outer peripheral surface (171) portion of the cap (16), and the axial extension portion (3241) portion of the can connection portion (324) of the second collector plate (32) are welded together at the abutting portion between the side wall member (11), the cap (16), and the second collector plate (32).

[0269] As shown, the axial end of the joint outer surface (171) of the cap (16) and the inner surface of the side wall member (11), which are radially opposed to each other, are exposed to the axial outer side.

[0270] The above welding part (W) is formed by a laser irradiating the axial end of the second inner surface (115) of the side wall member (11) and the joint outer surface (171) of the cap (16) from the axial outer side of the battery cell.

[0271] At this time, since the outer surface (325) of the second collector plate (32) positioned axially inner than the cap (16) faces and comes into contact with the inner surface of the side wall member (11), the laser is prevented from entering the internal space of the can through the gap between the side wall member (11) and the cap (16).

[0272] In addition, the inner diameter expansion portion (113) of the side wall member (11) also prevents the internal penetration of a laser that may enter through the gap between the side wall member (11) and the cap (16) or the second collector plate (32).

[0273] The above welding portion (W) includes a portion where at least a portion of the inner surface of the side wall member (11) and at least a portion of the mating outer surface (325) of the collector plate (32) are joined, a portion where at least a portion of the inner surface of the side wall member (11) and at least a portion of the joining outer surface (171) of the cap (16) are joined, and a portion where at least a portion of the cap mating surface (326) of the collector plate (32) and at least a portion of the collector plate mating surface (173) of the cap (16) are joined. Preferably, the joining outer surface (171) of the cap (16) can be entirely welded.

[0274] That is, the above welded portion (W) can be formed by triple welding.

[0275] The abutting portion of the side wall member (11) and the cap (16) is heated to a high temperature by a laser (L) that is irradiated to form the above welding portion (W).

[0276] Then, the heat generated in the side wall member (11) by the laser can be quickly dispersed and conducted through the second collector plate (32) having a wider contact area, and the heat generated in the cap (16) by the laser can be somewhat more slowly dispersed and conducted through the second collector plate (32) having a narrower contact area. Accordingly, the melting point of the side wall member (11), which is relatively thinner than the joint (17) of the cap (16), can be further delayed.

[0277] In addition, since most of the welding heat transmitted through the side wall member (11) is distributed through the second collector plate (32), the phenomenon of heat being transmitted toward the separator (28) of the electrode assembly (20) in contact with the first inner peripheral surface (111) of the side wall member (11) can be further reduced.

[0278] According to the present invention, the can connection part (324) and the outer bridge part (335) of the second current collector plate (32) are spaced apart from the electrode assembly (20) in the axial direction by a predetermined distance (g) by the first bend part (331) and the second bend part (332) provided in the bridge (33) of the second current collector plate (32), as illustrated in FIG. 17. In addition, as illustrated in FIG. 16, the second current collector plate (32) is spaced apart from the electrode assembly (20) in the axial direction by a predetermined radial width (r1) radially inward from the can connection part (324) by the first bend part (331).

[0279] Accordingly, in the process of welding the cap (16), the can (10), and the second collector plate (32), the welding heat transferred to the second collector plate (32) is conducted radially inwardly through the bridge (33) for a predetermined distance (r1) before reaching the surface of the electrode tab (27) of the electrode assembly (20). If the heat conduction path is set long in this way, the temperature drops significantly during the heat conduction process. Therefore, the heat conducted to the inner bridge portion (333) or the main body portion (320) does not have a significant effect on the electrode assembly (20).

[0280] Meanwhile, as previously described, 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. Accordingly, the depth at 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 bulging phenomenon of the cap (16) caused by an increase in internal pressure of the can (10) due to thermal runaway of the battery cell, etc., is determined by the second thickness (t2).

[0281] According to the present invention, even if welding is performed between the cap (16) and the side wall member (11) to a depth of the first thickness (t1), the abutting portion of the cap (16) and the side wall member (11) is completely bonded and connected, so that no portion where stress is concentrated occurs when bulging occurs, and the cap body (160) is made of a second thickness (t2) that is thicker, so that it can have greater bulging resistance.

[0282] In addition, according to the present invention, since the thickness reduction portion (161) of the cap (16) for interaction with the can connection portion (324) during the assembly process is positioned radially inward from the joint outer surface (171) only to an extent corresponding to the radial thickness of the can connection portion (324), the area of ​​the cap body (160) having the second thickness (t2) can be secured more widely, thereby further increasing the bulging resistance. Since a current collector plate such as the second current collector plate (32) is typically manufactured by a forming process that presses a thin metal sheet, it will be understood that the thickness reduction portion (161) can be positioned very close to the radial outer edge of the cap (16).

[0283] According to the embodiment described above, despite the wide range of the welding process, the weldability can be improved by securing sealing force without perforation or leakage, and the process stability can be improved by preventing thermal damage to cell components or separators due to welding heat, and the durability can also be improved by securing dimensional stability or bulging resistance by suppressing dimensional deformation due to internal pressure.

[0284] Referring to FIGS. 11 to 15 and FIG. 20 below, a first embodiment of a method for manufacturing the above-described battery cell will be described.

[0285] According to the manufacturing method of the above battery cell, first, a can (10) with a first electrode terminal (13) fixed to a bottom member (12) is prepared, and an electrode assembly (20) with a first collector plate (31) and a second collector plate (32) bonded to each of the axial ends is prepared.

[0286] Then, the electrode assembly (20) is inserted and accommodated in the can (10) with the first collector plate (31) facing the bottom member (12). Then, the second collector plate (32) is positioned toward the open end of the can (10). In the process of accommodating the electrode assembly (20) in the can (10), the mating outer surface (325) of the can connecting portion (324) provided at the radially outer edge of the second collector plate (32) is brought into contact with the first inner surface (111) of the side wall member (11).

[0287] Next, the first collector plate (31) and the first electrode terminal (13) are joined.

[0288] Then, the open end of the side wall member (11) is covered with a cap (16), and the outer surface of the joint (171) and the collector plate mating surface (173) provided on the edge of the cap (16) are brought into contact with the second inner surface (115) of the side wall member (11) and the cap mating surface (326) of the second collector plate (32), respectively.

[0289] At this time, the thickness reduction portion (161) in the form of an inclined surface provided on the axial inner surface of the cap (16) can be brought into contact with the second collector plate (32), thereby aligning the center of the cap (16) and pressing the axial outer end of the can connection portion (324) radially outward to bring it into contact with the second inner surface (115).

[0290] Next, a laser is irradiated from the axial outer side to the abutting portion of the second inner surface (115) of the side wall member (11) and the joint outer surface (171) of the cap (16), thereby triple-welding the inner surface of the side wall member (11), the joint portion (17) of the cap (16), and the can connection portion (324) of the second collector plate (32). The weld portion (W) thus formed joins the side wall member (11), the cap (16), and the second collector plate (32).

[0291] Next, the electrolyte is injected into the can (10) through the injection port (18) of the cap (16). After the electrolyte injection is completed, the injection port (18) is sealed with a stopper (40). The sealing of the injection port (18) can be accomplished, for example, by welding. However, such sealing can be accomplished by applying various known techniques capable of sealing joints.

[0292] Referring to Fig. 21, a second embodiment of a method for manufacturing a battery cell is described. The manufacturing method of the second embodiment is applicable when using a cap without a liquid filler port.

[0293] First, a can (10) with a first electrode terminal (13) fixed to a base member (12) is prepared, and an electrode assembly (20) with a first collector plate (31) and a second collector plate (32) joined to each of the axial ends is prepared.

[0294] Then, the electrode assembly (20) is inserted and accommodated in the can (10) with the first collector plate (31) facing the bottom member (12). Then, the second collector plate (32) is positioned toward the open end of the can (10). In the process of accommodating the electrode assembly (20) in the can (10), the mating outer surface (325) of the can connecting portion (324) provided at the radially outer edge of the second collector plate (32) is brought into contact with the first inner surface (111) of the side wall member (11).

[0295] Next, the first collector plate (31) and the first electrode terminal (13) are joined.

[0296] And, before covering the open end of the side wall member (11) with the cap (16), an electrolyte is injected into the inside of the can (10).

[0297]

[0298] After the electrolyte injection is completed, the open end of the side wall member (11) is covered with a cap (16), and the outer surface of the joint (171) and the collector plate mating surface (173) provided on the edge of the cap (16) are brought into contact with the second inner surface (115) of the side wall member (11) and the cap mating surface (326) of the second collector plate (32), respectively.

[0299] Next, a laser is irradiated from the axial outer side to the abutting portion of the second inner surface (115) of the side wall member (11) and the joint outer surface (171) of the cap (16), thereby triple-welding the inner surface of the side wall member (11), the joint portion (17) of the cap (16), and the can connection portion (324) of the second collector plate (32). The weld portion (W) thus formed joins the side wall member (11), the cap (16), and the second collector plate (32).

[0300] The battery cell (72) manufactured through the welding structure and welding process described above can be accommodated in the housing (71) of the battery pack (70) as illustrated in Fig. 22. The battery pack (70) may be configured using a battery module, which is an intermediate form of assembly, or the battery pack (70) may be configured directly without a battery module as illustrated.

[0301] Since the battery cell (72) described above has a large volume in itself, there is no particular difficulty in implementing a battery pack (70) even without using an intermediate structure called a battery module. Furthermore, the battery cell (72) has low internal resistance and a higher energy density. Accordingly, the energy density of a battery pack (70) equipped with the battery cell (72) can be implemented even higher.

[0302] A battery pack (70) with such a high energy density can store the same amount of energy while reducing its volume and weight. Therefore, when a battery pack (70) equipped with such battery cells (72) is installed in a vehicle, such as an automobile (80) that uses electricity as its energy source, as illustrated in FIG. 23, the vehicle's mileage per unit of energy consumed can be further increased.

[0303] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow, rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all possible modifications and variations derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0304] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

[0305] [Explanation of symbols]

[0306] 10: Can

[0307] 11: Side wall member

[0308] 111: First inner circle

[0309] 113: Inner diameter expansion

[0310] 115: Second inner surface (joint inner surface)

[0311] 12: Flooring

[0312] 13: First electrode terminal (positive terminal)

[0313] 14: Gasket

[0314] 15: Second electrode terminal

[0315] 16: Cap

[0316] 160: Cap body

[0317] t1: second thickness

[0318] 161: Thickness reduction section

[0319] 17: Joint

[0320] t2: first thickness

[0321] 171: Joint outer circumference

[0322] 173: The collector plate is facing each other

[0323] 18: Injection hole

[0324] 19: Insulator

[0325] 20: Electrode assembly

[0326] 21: First electrode

[0327] 22: Second electrode

[0328] 23: Metal foil

[0329] 24: Active material layer

[0330] 25: Maintenance Department

[0331] 26: Ministry of Immigration

[0332] 27: Electrode tab (notching tab)

[0333] 28: Membrane

[0334] 31: First collector plate (positive collector plate)

[0335] 312: Terminal connection

[0336] 313: Ringbu

[0337] 314: Electrode connection

[0338] 32: Second collector plate (negative collector plate)

[0339] 320: Main body

[0340] 321: Inner ring

[0341] 322: Hall

[0342] 323: Electrode tab connection

[0343] 324: Can connector

[0344] 3241: Axial extension

[0345] 3242: Radial extension

[0346] a: Section 1

[0347] 325: Matching outer circumference

[0348] 326: If the cap is aligned

[0349] 327: Bend

[0350] d: diameter

[0351] 33: Bridge

[0352] 331: First bend

[0353] 332: Second bend

[0354] b1, b2: bending angle

[0355] 333: Inner Bridge Section

[0356] 334: Offset bridge section

[0357] 335: Outer Bridge Department

[0358] 40: Stopper

[0359] H: Height of the second collector plate

[0360] g: axial spacing

[0361] r1: radial width

[0362] P: Forced fit

[0363] W: Welding

[0364] 70: Battery pack

[0365] 71: Housing

[0366] 72: Battery cell

[0367] 80: Vehicle

Claims

1. A battery cell including a can including a side wall member extending in the axial direction; and an open end provided at one axial end of the side wall member; a cap covering the open end; an electrode assembly accommodated inside the can; and a current collector electrically connecting the electrode assembly and the can. The above collector plate: A main body portion connected to the electrode tab of the above electrode assembly; A can connection portion positioned radially outside the main body portion and connected to at least one of the side wall member and the cap; and A bridge is included, the radially inner side being connected to the main body, the radially outer side being connected to the can connection part, and extending radially; The above bridge: A first bending portion that bends so that the extension direction of the bridge portion extending radially outward faces axially outward; A second bending portion that bends so that the extension direction of the bridge portion extending axially outward faces radially outward; and A battery cell comprising an offset bridge portion having a radially inner side connected to the first bend portion and a radially outer side connected to the second bend portion.

2. In claim 1, A battery cell in which the main body portion is positioned axially further inward than the can connection portion.

3. In claim 1, A battery cell, wherein the bridge further includes an inner bridge portion having a radially inner side connected to the main body portion and a radially outer side connected to the first bend portion.

4. In claim 1, A battery cell, wherein the bridge further includes an outer bridge portion having a radially inner side connected to the second bending portion and a radially outer side connected to the can connecting portion.

5. In claim 4, A battery cell in which the angle formed by the extension direction of the outer bridge portion with the radial direction is 10 degrees or less.

6. In claim 1, A battery cell in which the bending angle of the first bending portion is acute.

7. In claim 1, A battery cell in which the bending angle of the second bending portion is acute.

8. In claim 1, A battery cell wherein the difference between the bending angle of the first bending portion and the bending angle of the second bending portion is 10 degrees or less.

9. In claim 1, At one axial end of the above side wall member, An inner diameter expansion portion in which the inner diameter of the above side wall member is expanded; A first inner surface provided on the axial inner side of the above inner diameter expansion portion; and A battery cell, wherein a second inner surface is provided on the axial outer side of the inner diameter expansion portion and has an inner diameter larger than that of the first inner surface.

10. In claim 9, A battery cell in which the outer circumference of the can connection part of the above-mentioned collector plate is in contact with the first inner circumference.

11. In claim 9, A battery cell in which the outer circumference of the above cap is in contact with the second inner circumference.

12. In claim 1, The above can connection part is, An outer surface defined by the outer circumference of the can connection portion, facing the inner circumference of the side wall member in the radial direction, and having at least a portion of the axial section facing and contacting the inner circumference of the side wall member in the radial direction; and A battery cell, comprising a cap mating surface defined by an axial outer end of the can connection portion and facing and contacting the inner surface of the cap in the axial direction.

13. In claim 1, The above cap: The outer surface of the joint facing the inner surface of the side wall member in the radial direction; and A battery cell, comprising a current collector mating surface defined by the axial inner surface of the cap and facing and contacting the can connection portion of the current collector in the axial direction.

14. In claim 1, A battery cell in which at least a portion of the side wall member, at least a portion of the cap, and at least a portion of the can connection portion of the current collector plate are welded together.

15. In claim 12, A battery cell, wherein the portion where the inner surface of the side wall member and the outer surface that is mated are in contact includes a portion where the outer diameter of the outer surface that is mated is larger than the inner diameter of the inner surface of the side wall member and the outer surface that is mated is forcibly pressed into the side wall member.

16. In claim 1, A battery cell, wherein a bent portion is provided at the axial inner end of the above can connection portion so that the can connection portion extending radially outward is bent to extend axially outward.

17. In claim 1, A battery cell, wherein the cap is in contact with the current collector and has a pressing surface that presses the current collector radially outward.

18. In claim 17, A battery cell, wherein the above-mentioned pressure surface includes an inclined surface provided on the axial inner surface of the cap and extending axially outward as it goes radially outward.

19. A method for manufacturing a battery cell, comprising a can including a side wall member 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 inside the can, A first step of bonding a current collector to the above electrode assembly; A second step of inserting the current collector plate into the can and forcibly pressing at least a portion of the axial direction of the outer surface of the can connection portion provided on the radial outer edge of the current collector plate into the inner surface of the side wall member; A third step of covering the open end of the side wall member with a cap and contacting the radially outer edge of the cap with at least one of the can connection portions of the side wall member and the collector plate; and A method for manufacturing a battery cell, comprising a fourth step of welding together the side wall member, the cap, and the can connection portion of the current collector plate by irradiating a laser to the side wall member, the cap, and the can connection portion of the current collector plate.

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