Laser welding of an external tip stack of an electrode to a terminal

Abstract

The invention relates to laser welding of an external tab stack of an electrode to a terminal. A method for joining an external tab of a battery cell to a terminal includes: providing a battery cell stack; arranging an external tab stack of one of the C cathode electrodes and the A anode electrodes on the terminal; laser melting an end portion of the external tab stack; and after the laser melting, laser welding the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal.

Description

Technical Field

[0001] introduction

[0002] The information provided in this section is for the purpose of generally presenting the background of the present disclosure. The work of the presently named inventors, to the extent it is described in this section and in all aspects of this description that may not otherwise be considered prior art at the time of filing, is neither explicitly nor implicitly admitted to be prior art against the present disclosure.

[0003] The present disclosure relates to battery cells, and more particularly to laser welding an external tab stack of an electrode to a terminal of a battery cell. Background Art

[0004] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles include one or more motors and a battery system, which includes one or more battery cells, modules, and / or battery packs. A power control system is used to control the charging and / or discharging of the battery system during charging and / or driving. Summary of the invention

[0005] A method for coupling an external tab of a battery cell to a terminal, the method comprising providing a battery cell stack, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrodes, the anode electrodes comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S separators, wherein C, S, and A are integers greater than 1. The method comprises: arranging a stack of external tabs of one of the C cathode electrodes and the A anode electrodes on the terminal; laser melting an end of the stack of external tabs; and, after laser melting, laser welding the stack of external tabs of one of the C cathode electrodes and the A anode electrodes to the terminal.

[0006] In other features, a first laser heats an end of the outer tab stack and performs laser welding. The method includes adjusting at least one of a laser power, a laser scanning speed, a laser focus / defocus, a laser oscillation mode, a workpiece speed, a pulse frequency, and / or a pulse shape of the first laser between laser melting and laser welding.

[0007] In other features, the first laser performs laser melting and the second laser performs laser welding. The first laser uses different operating parameters than the second laser. At least one of the laser power, laser scanning speed, laser focus / defocus, workpiece speed, laser oscillation mode, pulse frequency and / or pulse shape of the second laser is different from the first laser.

[0008] A method for coupling an external tab of a battery cell to a terminal, the method comprising providing a battery cell stack, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrodes, the anode electrodes comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S separators, wherein C, S, and A are integers greater than 1. The method comprises: arranging a stack of external tabs of one of the C cathode electrodes and the A anode electrodes on the terminal; using a laser to generate L welds between the stack of external tabs and the terminal, wherein L is an integer greater than 1; and laser welding the stack of external tabs of one of the C cathode electrodes and the A anode electrodes to the terminal.

[0009] In other features, a first laser forms L spot welds and performs laser welding. The method includes adjusting at least one of a laser power, a laser scanning speed, a laser focus / defocus, a laser oscillation mode, a workpiece speed, a pulse frequency, and / or a pulse shape of the first laser between the L spot welds and the laser welding. The first laser forms the L spot welds and the second laser performs the laser welding. The first laser uses different operating parameters than the second laser.

[0010] In other features, at least one of laser power, laser scanning speed, laser focus / defocus, workpiece speed, laser oscillation mode, pulse frequency and / or pulse shape of the second laser is different from that of the first laser. The laser welding includes at least one of lap welding and edge welding.

[0011] A method for coupling an external tab of a battery cell to a terminal, the method comprising providing a battery cell stack, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrodes, the anode electrodes comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S separators, wherein C, S, and A are integers greater than 1. The method comprises forming a gas release channel between an external tab stack of one of the cathode electrode and the anode electrode and the terminal; and laser welding the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal.

[0012] In other features, forming the gas release channel includes disposing a rod on the terminal; and disposing an external tab stack of one of the C cathode electrodes and the A anode electrodes on the rod and the terminal to form the gas release channel.

[0013] In other features, the cross-section of the rod is selected from the group consisting of semicircular, rectangular, polygonal, triangular, square and circular.

[0014] In other features, forming the gas release channel also includes clamping the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal on opposite sides of the rod; and removing the rod between the external tab stack of one of the C cathode electrodes and the A anode electrodes and the terminal before laser welding.

[0015] In other features, the terminal includes a groove, and the gas release channel is formed between an external tab stack of one of the cathode electrode and the anode electrode and the groove of the terminal. The laser welding includes at least one of lap welding and edge welding.

[0016] A method for coupling an external tab of a battery cell to a terminal, the method comprising providing a battery cell stack, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrodes, the anode electrodes comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S separators, wherein C, S, and A are integers greater than 1. The method comprises arranging an external tab stack of one of the C cathode electrodes and the A anode electrodes at a first acute angle relative to the terminal; and laser welding an end of the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal.

[0017] In other features, the ends of the external tab stack are trimmed to a second acute angle prior to laser welding of the ends, and wherein the trimmed surface of the ends faces the terminal. The ends of the external tab stack are trimmed to a second acute angle prior to laser welding, and the trimmed surface of the ends faces away from the terminal, and also includes biasing the ends of the external tab stack against the terminal prior to laser welding the ends to cause the external tab stack to bend against the terminal.

[0018] A method for coupling an external tab of a battery cell to a terminal, the method comprising providing a battery cell stack, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrodes, the anode electrodes comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S separators, wherein C, S, and A are integers greater than 1. The method comprises arranging an external tab stack of one of the C cathode electrodes and the A anode electrodes against the terminal, wherein the length of the terminal is oriented within 30° of the vertical direction; laser heating the terminal over an end of the external tab stack so that a molten portion of the terminal flows onto the end of the external tab stack; and laser welding the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal.

[0019] The present disclosure also provides the following technical solutions:

[0020] 1. A method for coupling an external tab of a battery cell to a terminal, the method comprising:

[0021] A battery cell stack is provided, the battery cell stack comprising:

[0022] C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector;

[0023] A anode electrode, the anode electrode comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and

[0024] S partitions, where C, S and A are integers greater than 1;

[0025] placing an external tab stack of the C cathode electrodes and one of the A anode electrodes on a terminal;

[0026] laser melting ends of the external tab stack; and

[0027] After the laser melting, the external tab stack of one of the C cathode electrodes and the A anode electrodes is laser welded to the terminal.

[0028] 2. The method according to technical solution 1, wherein a first laser heats the end of the external tab stack and performs the laser welding.

[0029] 3. The method according to Technical Solution 2 further includes adjusting at least one of the laser power, laser scanning speed, laser focus / defocus, laser oscillation mode, workpiece speed, pulse frequency and / or pulse shape of the first laser between the laser melting and the laser welding.

[0030] 4. The method according to technical solution 1, wherein the first laser performs laser melting and the second laser performs laser welding.

[0031] 5. The method according to technical solution 4, wherein the first laser uses operating parameters different from those of the second laser.

[0032] 6. A method according to technical solution 4, wherein at least one of the laser power, laser scanning speed, laser focus / defocus, workpiece speed, laser oscillation mode, pulse frequency and / or pulse shape of the second laser is different from that of the first laser.

[0033] 7. A method for coupling an external tab of a battery cell to a terminal, the method comprising:

[0034] A battery cell stack is provided, the battery cell stack comprising:

[0035] C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector;

[0036] A anode electrode, the anode electrode comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and

[0037] S partitions, where C, S and A are integers greater than 1;

[0038] placing an external tab stack of the C cathode electrodes and one of the A anode electrodes on a terminal;

[0039] Using a laser to create L welds between the external tab stack and the terminal, where L is an integer greater than 1; and

[0040] The external tab stack of one of the C cathode electrodes and the A anode electrodes is laser welded to the terminal.

[0041] 8. The method according to technical solution 7, wherein the first laser forms L welding spots and performs laser welding.

[0042] 9. The method according to technical solution 8 further includes adjusting at least one of the laser power, laser scanning speed, laser focus / defocus, laser oscillation mode, workpiece speed, pulse frequency and / or pulse shape of the first laser between the L welds and the laser welding.

[0043] 10. The method according to technical solution 7, wherein the first laser forms L welding spots and the second laser performs laser welding.

[0044] 11. The method according to technical solution 10, wherein the first laser uses operating parameters different from those of the second laser.

[0045] 12. A method according to technical solution 10, wherein at least one of the laser power, laser scanning speed, laser focus / defocus, workpiece speed, laser oscillation mode, pulse frequency and / or pulse shape of the second laser is different from that of the first laser.

[0046] 13. The method according to Technical Solution 7, wherein the laser welding includes at least one of lap welding and edge welding.

[0047] 14. A method for coupling an external tab of a battery cell to a terminal, the method comprising:

[0048] A battery cell stack is provided, the battery cell stack comprising:

[0049] C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector;

[0050] A anode electrode, the anode electrode comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector;

[0051] S baffles, where C, S, and A are integers greater than 1; and

[0052] forming a gas release channel between an external tab stack and a terminal of one of the C cathode electrodes and the A anode electrodes; and

[0053] The external tab stack of one of the C cathode electrodes and the A anode electrodes is laser welded to the terminal.

[0054] 15. The method according to technical solution 14, wherein forming the gas release channel comprises:

[0055] arranging the rod on the terminal; and

[0056] An external tab stack of one of the C cathode electrodes and the A anode electrodes is arranged on the rod and the terminal to form the gas release channel.

[0057] 16. The method according to technical solution 15, wherein the cross-section of the rod is selected from the group consisting of semicircular, rectangular, polygonal, triangular, square and circular.

[0058] 17. The method according to technical solution 15, wherein forming the gas release channel further comprises:

[0059] clamping the external tab stack of one of the C cathode electrodes and the A anode electrodes to the terminal on opposite sides of the rod; and

[0060] The rod between the external tab stack and the terminal of one of the C cathode electrodes and the A anode electrodes is removed prior to the laser welding.

[0061] 18. The method according to technical solution 14, wherein the terminal includes a groove, and the gas release channel is formed between an external tab stack of one of the cathode electrode and the anode electrode and the groove of the terminal.

[0062] 19. The method according to Technical Solution 9, wherein the laser welding includes at least one of lap welding and edge welding.

[0063] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The present disclosure will become more fully understood through the detailed description and accompanying drawings, in which:

[0065] Figure 1 is a side cross-sectional view of an example of a battery cell including a cathode electrode, an anode electrode and a separator according to the present disclosure;

[0066] Figure 2A is a perspective view of an example of a pouch-type battery cell according to the present disclosure, the pouch-type battery cell including an external tab stack of an anode electrode or a cathode electrode welded to a terminal;

[0067] Figure 2B is a perspective view of an example of a prismatic battery cell according to the present disclosure, the prismatic battery cell including an external tab stack of an anode electrode or a cathode electrode welded to an internal terminal;

[0068] Figure 2C is a side cross-sectional view of an example of internal and external terminals of a prismatic battery cell according to the present disclosure;

[0069] Figures 3A to 3C illustrates an example of a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal disposed in a fixture by melting the external tab and then laser welding according to the present disclosure;

[0070] FIG. 4A to FIG. 4C illustrates another example of a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal by melting the external tab and then laser welding according to the present disclosure;

[0071] Figures 5A to 5C illustrates another example of a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal by laser spot welding and then laser welding according to the present disclosure;

[0072] FIG. 6A to FIG. 6C illustrates another example of a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal by clamping the external tab stack on a rod and then removing the rod to form a gas release channel in accordance with the present disclosure;

[0073] Figures 7A to 7C Another example of a method for laser welding an external tab stack of an anode electrode or a cathode electrode to a terminal including a groove forming a gas release channel according to the present disclosure is illustrated;

[0074] Fig. 8A and 8B Another example of a method for laser welding an end of an external tab stack of an anode electrode or cathode electrode to a terminal at an angle according to the present disclosure is illustrated;

[0075] Fig.9A and 9B illustrates another example of a method for laser welding an end of an external tab stack of an anode electrode or cathode electrode to a terminal at an angle according to the present disclosure; and

[0076] Figures 10A to 10D Another example of a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal using autogenous brazing according to the present disclosure is illustrated.

[0077] In the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0078] Although the battery cells including laser welded terminals are shown in the context of an electric vehicle, the battery cells including laser welded terminals may be used in stationary applications and / or other applications.

[0079] The present disclosure solves the problem of welding quality between external tabs extending from current collectors of anode and / or cathode electrodes and battery cell terminals. In some examples, the terminals are laser welded to the external tab stacks of cathode electrodes or anode electrodes in pouch-type battery cells. The terminals extend through the pouch-type housing.

[0080] In some examples, the terminals are internal terminals of the prismatic battery cell that contact external terminals of the prismatic battery cell. In other words, the external terminals contact internal terminals of external tabs that are laser welded to the cathode electrode and / or the anode electrode. It is understood that separate terminals are used to connect to the cathode and anode electrodes, respectively, to external devices. Although prismatic and pouch battery cells are shown for illustration purposes, other battery cell form factors may also be used.

[0081] When welding multiple layers of external tabs (e.g., external tabs extending from a current collector made of foil), the weld may be porous and separation may occur at the fusion boundary. When laser welding is used, defects may occur. The present disclosure relates to using various laser welding methods to connect a stack of external tabs of anode and / or cathode current collectors to terminals to reduce or eliminate defects and improve weld quality. In some examples, laser welding is performed with or without prior ultrasonic welding.

[0082] Reference now Figure 1 , the battery cell 10 includes C cathode electrodes 20, A anode electrodes 40, and S separators 32, which are arranged in a predetermined order in a stack 12, which is arranged in a housing 50. The cathode electrodes 20-1, 20-2, ... and 20-C (where C is an integer greater than 1) include a cathode active material layer 24 arranged on one side or both sides of a cathode current collector 26. The A anode electrodes 40-1, 40-2, ... and 40-A (where A is an integer greater than 1) include an anode active material layer 42 arranged on one side or both sides of an anode current collector 46.

[0083] Connections to the C cathode electrodes 20 and the A anode electrodes 40 are typically made to terminals. The C cathode electrodes 20 and the A anode electrodes 40 include external tabs 28 and 48, respectively. The external tabs correspond to portions of the current collectors of the C cathode electrodes 20 and the A anode electrodes 40 that extend beyond the edge of the cathode active material layer 24 or the anode active material layer 42.

[0084] In some examples, the external tabs 28 of the C cathode electrodes 20 are connected to one terminal, and the external tabs 48 of the A anode electrodes 40 are connected to another terminal. The terminals extend through the battery cell housing or are connected to the external terminals of the battery cell that extend through the battery cell housing. Although the lengths of the external tabs 28 and 48 are Figure 1 48 are shown as relatively short, but the external tabs 28 and 48 can extend any distance required for welding or other purposes. The external tabs 28 and 48 can include a single external tab per electrode, or can include multiple external tabs per electrode to provide redundant connections. The external tabs 28 and 48 can extend the width of the current collector or only a portion of the width of the current collector.

[0085] In some examples, the cathode current collector 26 and the anode current collector 46 include foil layers. In some examples, the current collector is made of one or more materials selected from the group including copper, stainless steel, brass, bronze, zinc, aluminum and alloys thereof. In some examples, the anode active material layer 42 and / or the cathode active material layer 24 include a free-standing cathode or anode active layer. In other examples, the anode active material layer 42 and / or the cathode active material layer 24 include a coating including one or more active materials, one or more conductive fillers / additives, and / or one or more adhesive materials. In some examples, the battery cells and / or electrodes are manufactured by applying a slurry to coat the current collector in a roll-to-roll manufacturing process.

[0086] Reference now Figure 2A , the pouch cell 52 includes a pouch housing 53 that includes a cell stack 56. As will be further described below, external tabs 57 of the anode and cathode electrodes are laser welded to terminals 54 and 55 extending through the pouch housing 53, respectively.

[0087] Reference now Figure 2B , the prismatic battery cell 58 includes a housing 60. In some examples, the housing 60 has a rectangular cross-section in the x, y, and z axis planes. The prismatic battery cell 58 includes external terminals 62 and 64 and a vent cap 66. The stack 12 of C cathode electrodes 20, A anode electrodes 40, and S separators 32 is arranged in the housing 60. As will be further described below, the external tabs of the anode current collector and / or cathode current collector are laser welded to the corresponding terminals. The terminals are arranged to contact the external terminals 62 and 64 of the battery cell 10 to provide external connections to the anode electrode and the cathode electrode.

[0088] Reference now Figure 2C, examples of internal terminals 84 and 86 of prismatic battery cells are shown in the housing 60. The stack 12 of A anode electrodes or C cathode electrodes includes an external tab 88. The external tabs 88 of the A anode electrodes and / or the C cathode electrodes are laser welded to the internal terminals 84 and 86, respectively, as will be further described below. Although the internal terminals 84 and 86 are shown as "L" shaped terminals, flat terminals or terminals having other shapes may be used.

[0089] Reference now Figures 3A to 3C , a method for laser welding an external tab stack 112 of an anode electrode or a cathode electrode of a battery cell stack 110 to a terminal 114 by melting and then laser welding the external tab stack 112 is shown. The external tab stack 112 and the terminal 114 are mounted in a fixture 124, which includes a clamp 122 that is configured to hold the external tab stack 112 and the terminal 114 together during laser welding. A scanner 132 is attached to the laser 130 and is configured to move a laser beam output by the laser 130 over the external tab stack 112 and / or the terminal 114. Although the scanner 132 can be used to move the laser 130, the fixture 124 can be moved by an actuator to move the battery cell stack 110 relative to the laser (e.g., instead of or in addition to movement of the scanner 132).

[0090] exist Figure 3A In the embodiment, the scanner 132 directs the laser beam output by the laser 130 onto the end 120 of the outer tab stack 112 to melt the end 120 of the outer tab stack 112. Figure 3B In FIG. 1 , the end 120 of the outer tab stack 112 is partially melted, as shown at 120 ′. Figure 3C In the embodiment of the present invention, the scanner 132 directs the laser beam output by the laser 130 onto the end 120 ′ of the external tab stack 112 and the terminal 114 to generate a weld 134 between the external tab stack 112 and the terminal 114 .

[0091] In some examples, the laser 130 is arranged at an acute angle relative to the external tab stack 112 and the terminal 114. In some examples, the laser 130 is defocused during melting and focused during laser welding. In some examples, the scanner 132 uses a first scanning speed during melting and a second scanning speed (less than the first scanning speed) during laser welding. In some examples, the laser 130 uses beam oscillation during laser welding. In some examples, the laser 130 uses power modulation during laser welding. It will be understood that the laser weld can partially or completely penetrate the terminal 114.

[0092] Reference now Figures 4A to 4C , a method for laser welding an external tab stack 212 of an anode electrode or cathode electrode of a battery cell stack 210 to a terminal 214 is shown. The external tab stack 212 and the terminal 214 are mounted in a fixture 224, which includes a clamp 222 configured to hold the external tab stack 212 and the terminal 214. The scanner 132 is attached to the laser 130 and is configured to direct the laser 130 onto the external tab stack 212 and / or the terminal 214.

[0093] exist Figure 4A In the embodiment, the scanner 132 directs the laser beam output by the laser 130 onto the end 220 of the outer tab stack 212 to melt the end 220 of the outer tab stack 212. Figure 4B In the embodiment, the end 220' of the outer tab stack 212 is melted. Figure 4C In the embodiment, the scanner 132 directs the laser beam outputted by the laser 130 onto the end 220 ′ of the external tab stack 212 and the terminal 214 to form a weld 234 between the external tab stack 212 and the terminal 214 .

[0094] In some examples, the laser 130 is arranged at an angle relative to the external tab stack 212 and the terminal 214. In some examples, the laser 130 is defocused during melting and focused during laser welding. In some examples, the scanner 132 uses a first scanning speed during melting and a second scanning speed (less than the first scanning speed) during laser welding. In some examples, the laser 130 uses beam oscillation during laser welding. In some examples, the laser 130 uses power modulation during laser welding. It will be appreciated that the laser weld may partially or completely penetrate the terminal 214.

[0095] Reference now Figures 5A to 5C , shows a method for laser welding an external tab stack 312 of an anode electrode or cathode electrode of a battery cell stack 310 to a terminal 314. Figure 5A and 5B , the scanner 132 moves the laser beam output by the laser 130 to a plurality of locations on the terminal 314 to generate a plurality of weld spots 316-1, ..., and 316-L, where L is an integer greater than 1. Prior to laser welding, the plurality of weld spots 316-1, ..., and 316-L secure the end of the external tab stack 312 to the terminal 314. In some examples, the plurality of weld spots 316-1, ..., and 316-L are arranged along one or more lines parallel to and spaced apart from the edge of the external tab stack 312.

[0096] After the plurality of spot tack welds 316-1, ... and 316-L are completed, the scanner 132 and laser 130 lap weld (or edge weld) the edge 320 of the outer tab stack 312 to the terminal 314. It is understood that the laser weld may partially or completely penetrate the terminal 314.

[0097] In some examples, the laser 130 is used for both spot welding and laser welding. In other examples, the first laser is used for spot welding and the second laser is used for laser welding. In some examples, the second laser produces a lap weld or edge weld between the external tab stack 312 and the terminal 314.

[0098] Reference now Figures 6A to 6C , shows a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal. Fig. 6A 4, the rod 420 is arranged on the surface of the terminal 414. The external tab stack 412 of the anode electrode or the cathode electrode in the battery cell stack 410 is arranged on the rod 420 and the terminal 414. The clamp 415 applies pressure to the external tab stack 412 on the opposite side of the rod 420.

[0099] like Figure 6B As shown, the outer tab stack 412 is deformed by the rod 420. Figure 6C 4, the rod 420 is removed after clamping. Since the external tab stack 412 is clamped on opposite sides of the rod 420, a gas release channel 424 extending from one side of the external tab stack 412 to the other side is created. In some examples, the rod 420 has a semicircular, polygonal, rectangular, triangular, square, circular or other regular or irregular cross-section. The scanner 132 and the laser 130 direct the laser beam onto the top surface and / or edge of the external tab stack 412 to weld the external tab stack 412 to the terminal 414. In some examples, the laser weld completely or partially penetrates the terminal 414.

[0100] Reference now Figures 7A to 7C , shows a method for laser welding an external tab stack of an anode electrode or cathode electrode to a terminal. Fig. 7A In the embodiment, the external tab stack 512 of the anode electrode or cathode electrode in the battery cell stack 510 is arranged on the terminal 514. The terminal 514 includes a groove 520 that extends the width of the terminal 514 and / or the width of the external tab stack 512. The groove 520 forms a gas release channel relative to the external tab stack 512 to release welding gas during laser welding. Figure 7CIn the embodiment, the scanner 132 and the laser 130 direct the laser beam 130 onto the top surface and / or edge of the external tab stack 412 to overlap or edge weld the external tab stack 412 to the terminal 414. In some examples, the laser weld penetrates the terminal 414 completely or partially.

[0101] Reference now Fig. 8A and 8B , a method for laser welding an external tab stack 612 of an anode electrode or a cathode electrode of a battery cell stack 610 to a terminal 614 is shown. The end 616 of the external tab stack 612 is optionally trimmed at a first predetermined acute angle α. The battery cell stack 610 maintains a second predetermined acute angle β relative to the terminal 614 (where the trimmed surface of the external tab stack 712 faces the terminal 714). In some examples, the first predetermined acute angle α and the second predetermined acute angle β are the same and / or within + / - 10°. In some examples, the first predetermined acute angle α and the second predetermined angle β are in the range of 30° to 60°.

[0102] The end 616 of the external tab stack 612 is moved to contact the soldering location on the terminal 614. In some examples, the plane including the end 616 of the external tab stack 612 is aligned with the plane including the facing surface of the terminal 614. Figure 8B , the scanner 132 and the laser 130 direct the laser beam across the end 616 of the external tab stack 612 to form a laser weld 624 between the external tab stack 612 and the terminal 614. In some examples, the laser weld penetrates the terminal 614 completely or partially.

[0103] Reference now Fig.9A and 9B , a method for laser welding an external tab stack 712 of an anode electrode or cathode electrode of a battery cell stack 710 to a terminal 714 is shown. An end 716 of the external tab stack 712 is trimmed at a first predetermined acute angle α. The battery cell stack 710 maintains a second predetermined acute angle β relative to the terminal 714 (where the trimmed surface of the external tab stack 712 faces away from the terminal 714). In some examples, the first predetermined acute angle α and the second predetermined acute angle β are the same and / or within + / -10°.

[0104] The end 716 of the external tab stack 712 is moved into contact with the terminal 614, and the external tab stack 612 is allowed to bend or flex. Figure 8B In the embodiment of the present invention, the scanner 132 and the laser 130 direct the laser beam across the end 716 of the external tab stack 712 to form a laser weld 724 between the external tab stack 712 and the terminal 714. In some examples, the laser weld penetrates the terminal 714 completely or partially.

[0105] Reference now Figures 10A to 10C , another example of a method for laser welding an external tab stack 812 of an anode electrode or cathode electrode of a stack 810 to a terminal 814 using autogenous brazing is shown. During laser welding, the stack 810 can be arranged in a fixture, such as a clamp. The scanner 132 and the laser 130 direct the laser beam to a surface 820 of the terminal 814 above the end 816 of the external tab stack 812. In some examples, the laser beam output by the laser 130 rotates, oscillates, or moves on the surface of the terminal 814.

[0106] In some examples, the ends 816 of the external tab stack 812 are trimmed at an acute angle (e.g., facing away from the contact surface of the terminal 814) prior to laser welding. In some examples, during laser welding, the terminal 814 and the stack 810 are tilted at an acute angle relative to the vertical direction so that the molten portion 822 of the terminal flows onto the ends 816 of the external tab stack 812. In some examples, the length of the terminal is vertically oriented to within 10° of the vertical direction, within 30° of the vertical direction, or at another suitable angle so that the molten portion of the terminal 814 flows onto the ends 816 of the external tab stack 812.

[0107] The laser 130 melts a surface 820 of the terminal 814 above the end 816 of the external tab 812. A molten portion 822 of the terminal 814 flows down onto the end 816 of the external tab stack 812. The scanner 132 then directs the laser 130 onto the molten portion 822 and the end 816 of the external tab stack 812 to laser weld the external tab stack 812 to the terminal 814. In some examples, the laser weld penetrates completely or partially through the terminal 814.

[0108] In some examples, the laser 130 is used for both melting and laser welding. In some examples, at least one of the laser power, laser scanning speed, laser focus / defocus, laser oscillation mode, workpiece speed, pulse frequency, and / or pulse shape of the first laser is adjusted during melting compared to during laser welding. In other examples, the first laser is used for melting the terminal 814 and the second laser is used for laser welding. In some examples, the first laser and the second laser use different operating parameters during melting and laser welding.

[0109] The foregoing description is merely illustrative in nature and is not intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, because other modifications will become apparent when studying the drawings, the specification and the following claims. It should be understood that one or more steps in the method can be performed in different orders (or simultaneously) without changing the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described in any embodiment of the present disclosure can be implemented in any of the other embodiments and / or combined with its features, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the transformation of one or more embodiments to each other is still within the scope of the present disclosure.

[0110] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "immediately adjacent," "on top of," "above," "below," and "disposed." Unless explicitly described as "directly," when describing a relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship in which no other intervening elements exist between the first element and the second element, but can also be an indirect relationship in which one or more intervening elements exist (either spatially or functionally) between the first element and the second element. As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean a logical (A or B or C) using a non-exclusive logical or, and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C."

[0111] In a diagram, the direction of the arrows, as indicated by the arrows, generally demonstrates the flow of information (e.g., data or instructions) of interest in the diagram. For example, when element A and element B exchange various information but the information transmitted from element A to element B is relevant to the diagram, the arrow may be directed from element A to element B. Such a unidirectional arrow does not mean that no other information is transmitted from element B to element A. In addition, for information sent from element A to element B, element B may send a request for the information or a receipt confirmation to element A.

Claims

1. A method for coupling an external tab of a battery cell to a terminal, the method comprising: A battery cell stack is provided, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrode, the anode electrode comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S partitions, where C, S and A are integers greater than 1; placing an external tab stack of the C cathode electrodes and one of the A anode electrodes on a terminal; laser melting ends of the external tab stack; and After the laser melting, the external tab stack of one of the C cathode electrodes and the A anode electrodes is laser welded to the terminal.

2. The method according to claim 1, wherein: A first laser heats the end of the external tab stack and performs the laser welding.

3. The method according to claim 2, further comprising adjusting at least one of laser power, laser scanning speed, laser focus / defocus, laser oscillation mode, workpiece speed, pulse frequency and / or pulse shape of the first laser between the laser melting and the laser welding.

4. The method according to claim 1, wherein: The first laser performs laser melting and the second laser performs laser welding.

5. The method according to claim 4, wherein: The first laser uses different operating parameters than the second laser.

6. The method according to claim 4, wherein: At least one of laser power, laser scanning speed, laser focus / defocus, workpiece speed, laser oscillation mode, pulse frequency and / or pulse shape of the second laser is different from that of the first laser.

7. A method for coupling an external tab of a battery cell to a terminal, the method comprising: A battery cell stack is provided, the battery cell stack comprising: C cathode electrodes, each cathode electrode comprising a cathode current collector made of foil, a cathode active layer disposed on the cathode current collector, and an external tab extending from the cathode current collector; A anode electrode, the anode electrode comprising an anode current collector made of foil, an anode active layer disposed on the anode current collector, and an external tab extending from the anode current collector; and S partitions, where C, S and A are integers greater than 1; placing an external tab stack of the C cathode electrodes and one of the A anode electrodes on a terminal; Using a laser to create L welds between the external tab stack and the terminal, where L is an integer greater than 1; and The external tab stack of one of the C cathode electrodes and the A anode electrodes is laser welded to the terminal.

8. The method according to claim 7, wherein: The first laser forms L welding spots and performs laser welding.

9. The method of claim 8, further comprising adjusting at least one of laser power, laser scanning speed, laser focus / defocus, laser oscillation mode, workpiece speed, pulse frequency and / or pulse shape of the first laser between the L weld spots and the laser welding.

10. The method according to claim 7, wherein: The first laser forms L weld spots and the second laser performs laser welding.

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