Battery terminal micro soldering

Abstract

The example illustration relates to a method and apparatus including a battery cell with a weld seam. In the example method, a laser is moved to a shoulder of the battery cell. The method may further include micro-welding a first segment on the shoulder of the battery cell with the laser, and moving the laser a certain distance on the shoulder of the battery cell. The method may also include micro-welding a second segment on the shoulder of the battery cell with the laser in response to moving the laser that distance. For example, an example battery cell assembly for a battery pack may have a battery cell and a weld seam on the shoulder of the battery cell. The weld seam may include a first micro-welded segment and a second micro-welded segment spaced apart by a distance.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 246,236, filed September 20, 2021, the contents of which are expressly incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to systems and methods for manufacturing and assembling battery cell arrays. Background Technology

[0004] As the use of combustion-based power sources shifts to renewable and less polluting resources such as wind, solar, and nuclear power, storing and utilizing significant levels of electrical energy becomes increasingly important. Storing energy for applications with high current / voltage demands over extended periods (e.g., powering large / heavy-duty vehicles) can utilize a large number of battery cells (e.g., thousands) that store energy within them, along with infrastructure to deliver high levels of power to their destinations.

[0005] Importantly, the interconnection of numerous battery cells allows for high-power surges and requires consistent manufacturing. One electrical connection technology is laser welding, which can be sensitive to variations in the process. For example, variations in welding power or intensity, welding speed, etc., may result in incorrect energy levels being applied to the joint. Applying too much energy can cause the weld to over-penetrate the joint. On the other hand, insufficient energy input may prevent the contacts from adequately connecting to the substrate. Both situations reduce the efficiency of power transfer to / from the battery cell. Therefore, there is a need to improve the consistency of the energy input to the laser weld joint to reduce the incidence of incorrect weld penetration. Summary of the Invention

[0006] In at least some example methods, one method includes moving a laser to the shoulder of a battery cell and micro-welding a first line segment on the shoulder of the battery cell using the laser. The method may further include moving the laser a certain distance on the shoulder of the battery cell. The method may also include micro-welding a second line segment on the shoulder of the battery cell using the laser in response to moving the laser that distance.

[0007] In at least some example methods, the distance includes a predetermined distance, and moving the laser on the shoulder of the battery cell by this distance includes moving the laser on the shoulder of the battery cell by the predetermined distance. The method may further include turning on the laser to micro-weld a first segment, turning off the laser before moving the laser by the predetermined distance, and turning on the laser to micro-weld a second segment in response to moving the laser by the predetermined distance.

[0008] In at least some of the example examples, a method further includes, after micro-welding a second segment, turning off a laser, moving the laser a plurality of predetermined distances from the second segment in response to turning off the laser, and turning on the laser to micro-weld a third segment in response to moving the laser a plurality of predetermined distances.

[0009] In at least some example methods, moving the laser to the shoulder of the battery cell includes moving the laser to a first portion of the battery cell to micro-weld a first line segment. Alternatively, moving the laser a certain distance on the shoulder of the battery cell includes moving that distance to a second portion of the battery cell to micro-weld a second line segment.

[0010] In at least some examples, the method further includes moving the laser from the second part to the third part of the battery cell, and micro-welding the third segment in response to moving the laser from the second part to the third part.

[0011] In at least some example methods, the second and third line segments are on opposite sides of the first line segment.

[0012] In at least some examples, the first line segment is formed in the central portion of the weld.

[0013] In at least some examples, the first line segment and the second line segment extend along a first direction on the shoulder of the battery cell, and the distance extends along a direction perpendicular to the first line segment.

[0014] In at least some example methods, the first and second line segments form a weld between the contact and the shoulder of the battery cell.

[0015] In at least some of the example examples, the method also includes forming a first weld-free zone around the first line segment and forming a second weld-free zone around the second line segment.

[0016] In at least some example methods, the length of each of the first and second segments does not exceed 700 micrometers.

[0017] In at least some examples, the second line segment is parallel to the first line segment.

[0018] In at least some examples, the battery is typically cylindrical.

[0019] In at least some examples, a battery cell assembly is provided, including a battery cell and a weld on the shoulder of the battery cell. The weld includes a first micro-welded line segment and a second micro-welded line segment spaced apart by a distance.

[0020] In at least some example methods, the length of each of the first and second micro-welding lines does not exceed 700 micrometers.

[0021] In at least some examples, the first micro-welding line and the second micro-welding line are parallel to each other, and the distance is perpendicular to the first micro-welding line segment and the second micro-welding line segment.

[0022] In at least some example methods, the battery pack includes multiple battery cells and multiple weld seams. Each battery cell has one weld seam on its shoulder, wherein each weld seam includes a first micro-welded line segment and a second micro-welded line segment spaced apart by a certain distance.

[0023] In at least some examples, the length of each of the first and second micro-welding lines does not exceed 700 micrometers.

[0024] In at least some examples, the first micro-welding line and the second micro-welding line are parallel to each other, and the distance is perpendicular to the first micro-welding line and the second micro-welding line.

[0025] In at least some example methods, the first micro-welding segment of each weld is arranged as a second micro-welding segment parallel to the weld.

[0026] In at least some example methods, the battery pack further includes a negative contact that is connected to the battery cell via a weld. Attached Figure Description

[0027] The above and other features, properties, and various advantages of this disclosure will become more apparent when considering the following specific embodiments in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 These are illustrative diagrams of battery cell arrays and potential welding sites according to some embodiments of this disclosure;

[0029] Figure 2 Examples of some embodiments according to this disclosure are shown by means of... Figure 1 A cross-sectional view of the battery cells and electrical contacts of the battery pack, taken from line 2-2;

[0030] Figure 3A A first cross-sectional view is shown of the welding site between the battery cell substrate and the electrical contacts according to some embodiments of the present disclosure.

[0031] Figure 3B This disclosure illustrates some embodiments relative to... Figure 3A The cross-sectional view is taken at a 90-degree angle. Figure 3A A second cross-sectional view of the welding site;

[0032] Figure 4 This is a top view of a welding process for battery cells and contacts according to some embodiments of this disclosure;

[0033] Figure 5 This is a top view of another welding of battery cells and contacts according to some embodiments of this disclosure;

[0034] Figures 6A to 6I This is a cross-sectional view of each weld completed between the substrate of the battery cell and the segmented electrical contacts according to some embodiments of this disclosure;

[0035] Figure 7 An exemplary welding system according to some embodiments of this disclosure is shown; and

[0036] Figure 8 A flowchart illustrating an exemplary process for soldering electrical contacts to a substrate according to some embodiments of the present disclosure is shown. Detailed Implementation

[0037] For example, the battery of an electric vehicle may be a battery pack having multiple battery cells, and in some cases, a large number (e.g., thousands) of battery cells, configured to provide electrical energy to propel the vehicle. In the exemplary embodiments described herein, multiple battery cells are electrically connected together via one or more contacts or current collectors. The current collector may be electrically connected to one or more busbars. Thus, power can be supplied from the battery pack via the contacts, current collectors, and busbars. Furthermore, the battery pack can be recharged via the contacts, current collectors, and busbars, for example, by regenerative power generated by the vehicle or a charging station or other external power source. More specifically, the positive and negative terminals of the cells may be electrically connected via corresponding positive and negative contacts. In some exemplary methods, these electrical contacts may be formed of a relatively thin metallic material (e.g., foil and / or aluminum). For example, the contacts may be micro-welded to the battery cells via laser welding.

[0038] Now for reference Figure 1 A portion of an example battery pack 100 is shown in a plan view or top view, with a portion of it magnified. Pack 100 includes a plurality of battery cells 102. Cells 102 can be of any convenient configuration or type. In this example, cell 102 is a cylindrical 2170 type lithium-ion battery cell. In another example, cell 102 is a prismatic battery cell.

[0039] Each cell 102 includes a battery positive terminal 104, and the group 100 also includes a positive contact 106 for electrically connecting the battery positive terminal 104 of each cell 102 to a positive current collector 108 of the group 100. As shown, the contact 106 may have a generally circular tab shape. Additionally, the negative current collector 112 of the group 100 may include a negative contact 110 for electrically connecting to the negative terminal 105 of each battery cell 102. As shown, the negative contact 110 may include a generally curved section, for example, corresponding to the cylindrical shape of the cell 102. The positive terminal 104 and the negative terminal 105 may each be any terminal or region of the battery that can be positively or negatively connected. The positive contact 106 and the negative contact 110 may each be any electrical contact that can be positively or negatively connected to the cell 102, respectively, to facilitate electrical communication between the cell 102 and a load or power source.

[0040] The positive terminal 104 and negative terminal 105 of each unit can be micro-welded to the positive contact 106 and negative contact 110, respectively. In this example, a laser welding process is used to weld each positive terminal 104 to the corresponding contact 106, applying multiple weld points to form one or more distinct weld seams 114. Figure 1 As shown in the example, each positive terminal 104 is connected to a single positive contact 106 via two different welds 114a and 114b (collectively referred to as 114), although any convenient number of welds 114 can be used. Furthermore, a laser welding process can be used to weld the negative terminal 105 of each unit 102 to the negative contact 110. More specifically, each negative contact 110 is connected to the lower negative terminal 105 of two adjacent units 102 via four welds 116a and 116b (collectively referred to as 116), two of which are applied to each adjacent unit 102. Thus, terminals 104 and 105 can each be connected to their respective contacts 106 and 110 via welds 114 and welds 116, respectively.

[0041] Now for reference Figure 2 The diagram shows a cross-sectional view of the upper shoulder 111 of one of the battery cells 102 according to an example method. While cell 102 is shown as generally cylindrical, any other shape or construction of cell 102 may be used. As an example only, cell 102 may be prismatic. As described above, battery cell 102 includes a positive terminal 104 at the center of the circular upper surface of cell 102 and a negative terminal 105 extending circumferentially around the radially outer shoulder region 111. Positive contacts 106 can electrically connect the positive terminals 104 of a plurality of additional battery cells 102 together (see [reference]). Figure 1Similarly, negative contact 110 can electrically connect the negative terminals 105 of the auxiliary battery unit 102 together. As described above, each negative terminal 105 can be micro-welded to negative contact 110, and positive terminal 104 can be micro-welded to positive contact 106 via one or more weld seams. Also as described above, in some example methods, laser welding can be used to weld terminals 104 and 105 to electrical contacts 106 and 110, respectively.

[0042] In some examples, the shoulder region 111 of the battery cell is relatively narrow in the radial direction, for example, about 700 micrometers wide. The shoulder region 111 of the battery cell 102 may be formed of a rolled material (along the radial outer edge) that radially surrounds a gasket 113, which electrically separates the negative terminal 105 from the positive terminal 104 at the center / button area of ​​the battery cell 102. The gasket 113 may be formed of an electrically insulating material, such as nylon, polypropylene, or polybutylene terephthalate (PBT), by way of example only.

[0043] Now for reference Figure 3A and Figure 3B An exemplary micro-solder joint 120 for electrical contact, for example, with the positive or negative terminal of a battery cell, is shown in a segment perpendicular to each other. As will be further discussed below, the example weld may have multiple different solder joints 120 within the segment. Typically, the example micro-solder joint 120 may be formed in a line or line segment such that its width is substantially smaller than the length of the micro-solder joint 120, such as... Figure 3A and 3B As shown in the example. In this example, the electrical contact (e.g., negative contact 110) can be a cover plate whose height H1 is relatively small compared to the height H2 of the electrical terminal (e.g., negative terminal 105), thus forming a terminal substrate for the weld. In one example, the electrical contact / cover plate 110 can be formed of 125µm thick aluminum material (e.g., 3003 series aluminum), while the terminal 105, which forms the substrate and thus the terminal substrate, is 250µm thick nickel-plated steel material. Furthermore, the micro-solders 120 each penetrate the terminal substrate 105 of the battery without penetrating the maximum thickness of the terminal 105. In other words, as Figure 3B As shown, the soldering depth T1 of the micro solder joint 120 in the terminal 105 is less than the maximum thickness T2 of the terminal 105 of the substrate forming the micro solder joint 120.

[0044] Refer again Figure 1 and Figure 2As shown in the figure, in some example methods, a first pass of the laser welding process can be initiated on the positive terminals 104 of cell 102 and their corresponding positive contacts 106, thereby connecting the positive contacts 106 to the lower positive terminals 104 of the battery cell 102 along a first weld 114a of each. Subsequently, a second pass of the laser can pass through the positive contacts 106, thereby forming a second weld 114b connecting the positive contacts 106 to the lower positive terminals 104 of the battery cell.

[0045] As also shown in the figures, in some example methods, a first pass of the laser welding process can be initiated on the negative contact 110 to connect the negative contact 110 to the lower negative terminal 105 of the battery cell 102 to form a first plurality of welds 116a. Subsequently, a second pass of laser welding can be initiated on the negative contact 110 to form welds 116b connecting the negative contact 110 to the lower negative terminal 105 of the battery cell 102. As will be further discussed below, each of welds 116a and welds 116b may have a plurality of micro-weld points 120. Furthermore, in at least some example methods, welds 114a and 114b from the positive contact 106 to the positive terminal 104 may also each include a plurality of micro-weld points 120.

[0046] While any convenient number and configuration of solder points 120 and weld seams 114 / 116 may be used, in the example shown, each positive terminal 104 is connected to the corresponding tab of the positive contact 106 via two separate weld seams 114, while each negative terminal 105 is connected to the corresponding negative contact 110 via four separate weld seams 116.

[0047] Turn now Figure 4 and Figure 5 Further detailed examples and descriptions of example welds (e.g., weld 114 and weld 116) are provided. More specifically, Figure 4 An example weld 114 is shown from the positive contact 106 to the positive terminal 104 of the battery cell 102, while Figure 5 An example weld 116 is shown from the negative contact 110 to the negative terminal 105 of the battery cell 102.

[0048] like Figure 4 and Figure 5 As shown in each of the examples, in the example method, the welded area or weld 114 / 116 includes a plurality of micro-solder points 120. Each micro-solder point 120 extends in line segment 123, as will be discussed further below. Each micro-solder point 120 is spaced apart from adjacent micro-solder points 120 such that a weld-free area 122 extends around the entire periphery of each micro-solder point 120. Therefore, the weld-free area 122 surrounds the micro-solder point 120. For example, as... Figure 4 and Figure 5As seen in the diagram, when viewed from above, each of the micro-solder points 120 is surrounded by a non-soldering area 122. This generally avoids unwanted spikes or "keyhole" shaped welds, for example, by preventing weld power concentration when the laser welding beam changes direction. In other words, confining the weld points within weld 114 and / or weld 116 to the line segments 123 provided by the micro-solder points 120 prevents the welding laser from slowing down around the curve in the welding path and prevents overheating of the material in weld 114 and / or weld 116. Therefore, compared to previous methods where there is a risk of overheating of the material in the weld, the spaced-out line segments 123 of the micro-solder points 120 shown advantageously form relatively shallow or conductive welds, which improve strength compared to deeper, narrower keyhole welds, as discussed further below. Example micro-solder joint 120 can be a line segment 123 with relatively small length and width, thereby allowing welding laser power to be applied in a relatively small area (such as the shoulder area 111 of battery cell 102) to form a relatively strong conductive solder joint.

[0049] exist Figure 4 In the example weld 114 shown, multiple segments 123 of the micro-weld points 120 are arranged substantially parallel to each other in a weld that is typically square or rectangular. The segments 123 of the micro-weld points 120 in weld 114 may be perpendicular to a path 132a obtained by a welding laser used to form the micro-weld points 120. In contrast, Figure 5 The weld 116 shown extends along a normally curved interface, for example, between the shoulder region 111 of the battery cell 102 and the associated electrical contact 110 of the battery pack 100.

[0050] As shown, weld 116 comprises twelve (12) spaced micro-solder points 120a-l (collectively referred to as 120), which are formed on corresponding line segments 123a-l (collectively referred to as 123). Line segments 123 are arranged on the shoulder region 111 of battery cell 102 such that they are longitudinally offset from each other, or offset in a direction perpendicular to the lateral spacing of the micro-solder points 120. The lateral spacing between line segments 123 may be defined by a distance D. For example, a distance D may be predetermined based on the desired spacing between the micro-solder points 120. Each line segment 123 may extend from radially outer (relative to the shoulder region 111 of battery cell 102) endpoints 121a to radially inner endpoints 121b. In addition, one or both ends of the micro-solder points 120 may be longitudinally offset from the laterally adjacent micro-solder points 120. Therefore, the micro-solder joints 120 are arranged within a weld seam 116, which is typically parallelogram-shaped, wherein the radially outer endpoint 121a of each line segment 123 is offset longitudinally (i.e., in a direction parallel to the line segment 123) from the radially outer endpoint 121a of the adjacent line segment 123. Similarly, the radially inner endpoint 121b of each line segment 123 is offset longitudinally from the radially inner endpoint 121b of the adjacent line segment 123. Thus, the radially outer endpoint 121a extends along the radially outer edge of the shoulder 111 of the battery cell 102. The radially inner endpoint 121b extends along the shoulder 111 at a position radially inside the radially outer endpoint 121a. As will be further discussed below, the line segments 123 of the micro-solder joints may be of the same length. In one example, each line segment 123 extends no more than 700 micrometers, corresponding to the radial width of the shoulder region 111 or an assumed flat region.

[0051] As mentioned above, it is generally desirable to avoid spiked welds or "keyhole" welds, for example, by preventing extreme or localized concentrations of welding power in the laser welding beam. Therefore, the power, speed, intensity, and / or other parameters of the laser welding apparatus or laser welding beam can be adjusted to promote the formation of relatively strong (relative to spiked / keyhole welds) conductive welds. In at least some example methods, the laser speed along the weld seam can range from 500 mm / s to 3500 mm / s. In one example, this speed is 2040 mm / s.

[0052] The size of the micro-solder joint 120 can be any convenient size. As described above, in at least some example methods in which the micro-solder joint 120 is formed on the shoulder region 111 of the battery cell 102, the width of the underlying substrate provided by the cell terminal 105 can be about 700 mm, and thus in these examples, the micro-solder joint 120 can have a corresponding or similar length (e.g., a length of 700 mm). Additionally, as discussed herein, the micro-solder joints 120 of the weld 116 can typically have a spacing or distance D that separates each micro-solder joint 120 by 100-400 mm; in one example, the distance D is 250 mm. In some examples, a minimum peel strength associated with the weld 116 can be achieved, for example, a peel strength of 7 Newtons (N).

[0053] Micro solder joint 120 Figure 5 The positioning within the parallelogram weld 116 may be advantageous for the degree of flexibility of the lower electrical terminals 105 of the battery cell 102, for example, in Figure 1 and Figures 3A to 3B With respect to the negative contact 110 of the shoulder 111 of the battery cell 102 shown. For example, each micro-solder joint 120 may be offset from the adjacent micro-solder joint 120 to provide a parallelogram shape. Furthermore, each micro-solder joint 120 may define an oblique angle relative to the path 132b of the welding laser used to form the micro-solder joint 120. In contrast, in Figure 4 In the example weld 114 shown, the two ends of each line segment 123 forming the micro-solder point 120 are aligned with the ends of the laterally adjacent micro-solder points 120. Therefore, the weld 114 defines a square or rectangular shape.

[0054] In at least some examples, welds (such as...) Figure 4 and Figure 5 The welds 114 / 116 shown can be formed in a "center-outward" manner, for example, initially forming one micro-weld point 120 centrally located, and then forming additional micro-weld points 120 on either side. Subsequently, other micro-weld points 120 can be formed alternately in the weld on either side. In some examples, the first micro-weld point 120 of weld 114 / 116 is formed in the central portion 150 of weld 114 / 116, wherein subsequent micro-weld points 120 are formed in the outer portion 152 or outer portion 154. Furthermore, as shown by... Figure 4 and Figure 5 As indicated by the pointing arrows shown and further discussed below, in some examples, the micro-solder joints 120 may be formed as a "zigzag" pattern, for example, in which a first solder joint 120 is formed using a laser traveling in a first direction, wherein subsequent micro-solder joints 120 are formed by lasers traveling in different or opposite directions as the first micro-solder joint 120. In other words, as... Figure 4As shown in the example welding area 130a, a first micro-solder joint 120 may begin to form at a first axis 140a and end at a second axis 140b, wherein a second micro-solder joint 120 begins to form at the second axis 140b and ends at the first axis 140a. Similarly, as Figure 5 As shown in the example weld area 130b, a first micro-weld point 120 may begin to form at a first axis 142a and end at a second axis 142b, wherein a second micro-weld point 120 begins to form at the second axis 142b and ends at the first axis 142a. Forming the weld points 120 in a zigzag pattern on alternating sides of the weld area or weld region and / or within the weld area or weld region allows the heat generated by welding (e.g., by laser welding) to diffuse outward from the central portion 150 to the outer portions 152 and / or 154. Therefore, by forming weld points in a generally extended manner (e.g., gradually outward from each side), localized or extreme concentrations of welding power due to energy intensity and duration (which could otherwise lead to spiked weld points or keyhole weld points) are avoided. This may be particularly advantageous when the welds 114 / 116 involved are relatively small, for example, as... Figure 4 and Figure 5 As shown in the image. This is merely an example. Figure 4 and Figure 5 The respective areas of the welding regions 130 shown do not exceed 7.5 square millimeters. More specifically, Figure 4 Weld 114 is approximately 1.5 mm wide and 5 mm long. (Included in...) Figure 4 Each of the ten (10) spaced micro-weld points 120 in the weld is linear and approximately 1.5 mm wide. Figure 5 In the example shown, each of the spaced micro-solder dots 120 of weld 116 is approximately 700 micrometers (0.7 mm) long and, in any case, does not exceed 700 micrometers in width of the shoulder region 111. Therefore, the width of the weld area 130b is less than 1.0 mm and extends approximately 2 mm along the weld path 132b. In one example, the length of the spaced micro-solder dots 120 corresponds to, for example... Figure 1 and Figure 2 The lower battery terminal substrate of the shoulder region 111 of the battery cell 102 shown. Although in Figure 5 The weld shows twelve (12) spaced micro-weld points 120, wherein a weld-free area 122 is positioned around each weld point 120, thereby surrounding the weld point 120, but any convenient number of spaced weld points can be used. By way of example only, ten or eleven spaced weld points 120 can be used. Furthermore, as in Figure 4 As can be seen in the example weld area 130a and as described above, in some examples, the weld point 120 may extend at an angle perpendicular to the weld path 132a. In contrast, in Figure 5 In the example weld area 130b, in other examples, the weld point 120 may be defined at an angle (i.e., non-parallel and non-perpendicular) relative to the weld path 132b.

[0055] As mentioned above, in Figure 5 In the example weld 116 shown, each micro-solder point 120 is spaced apart by a distance D. The distance D can be determined based on the desired spacing of the micro-solder points 120, which may depend on factors such as the cover plate (e.g., contact 110, see...). Figure 3A / Figure 3B The thickness of the substrate (e.g., terminal 105, see...) is related to the thickness of the substrate. Figure 3A / Figure 3B Factors such as the thickness ratio, the power of the welding laser, and / or the beam diameter of the welding laser. In one example, [the following will be used]. Figure 5 The distance D between the micro-solder points 120 is 100 to 400 µm. In another example, the distance D is 250 µm. In this example, the thickness of the cladding of the weld 116 (e.g., contact 110) can be approximately half the thickness of the underlying substrate (e.g., terminal 105). In another example, the thickness of the cladding / contact 110 is 125 µm and the thickness of the underlying substrate / terminal 105 is 250 µm. Continuing with this example, the laser used to weld the contact 110 to the terminal 105 is a foil welding laser. In this example, a fiber laser is used, which is a Class 4 continuous wave laser, for example, with a maximum power output of 1200 watts. In this example, the wavelength of the welding laser is 1070 nanometers (nm), although any other convenient wavelength can be used. The focal length of the laser beam, the beam size at the lens, and the beam diameter at the workpiece can also be any convenient value. In one example, a focal length of 441.6 mm is used in conjunction with a 15 mm beam size at the lens. The beam diameter at the workpiece (i.e., the cover plate / substrate) is typically between 20 µm and 40 µm. In one example, the beam diameter is 31 µm. The laser power can also be adjusted during the welding process, for example, to increase the power used for the subsequent formation of the micro-solder joints 120. For example, in Figure 5 In the example weld 116 shown, micro-solder joint 120a can be formed with a relatively reduced power level, while subsequent micro-solder joints 120b, 120c, 120d, etc., are formed with a relatively higher power level. In some methods, the relatively higher power level can be several times the power level used to form the first micro-solder joint 120a. In some examples, the relatively higher power level can be thirty times greater than the power level used to form the first micro-solder joint 120a.

[0056] Turn now Figures 6A to 6IThe diagram illustrates an example solder joint from electrical contacts to electrical terminals, such as those formed along the shoulder region 111 of battery cell 102 in electrical contacts 110 and lower terminals 105. As shown, solder joints 120 are typically shallow, preventing them from extending through the substrate (e.g., negative terminal 105). Therefore, the thermal insulation material 107 and terminals located beneath each micro-solder joint 120 are not damaged by the soldering process. Furthermore, as described above, the conductive or convection solder joints shown are relatively more robust than spiked or keyhole solder joints.

[0057] Turn now Figure 7 This illustration shows an exemplary welding system 700, for example, for welding battery cells and contacts together, according to some embodiments of the present disclosure. The welding system 700 may include processing circuitry 704, which may include any suitable software, hardware, or both for guiding welding equipment 706. Processing circuitry 704 may provide information indicating the location of any suitable components to be micro-welded, such as that described above, to guide welding equipment 706. For example, information indicating the location of battery terminals, contacts, overlapping areas between terminals and contacts, any suitable reference position features, etc., may be provided by processing circuitry 704.

[0058] The processing circuit 704 may communicate with one or more sensors 702, which may include imaging devices such as image sensors (e.g., photodetectors or cameras for detecting visible light or any other suitable photon signals), lidar devices, proximity sensors, Doppler effect-based devices, any other suitable sensors or imaging devices for determining the location of welds, or any combination thereof.

[0059] Processing circuitry 704 includes any suitable software, hardware, or both, for generating welding control signals 710. Control signals 710 may include, for example, welding paths, signals indicating when the laser should be turned on, laser power levels, etc. Welding control signals 710 are transmitted to welding equipment 706 using any suitable hardware and communication protocols (e.g., wired, wireless, or optical communication). Processing circuitry 704 may include, for example, one or more computing devices having one or more processors capable of executing instructions based on input. For example, processing circuitry 704 may include a computer, mobile / tablet computing device, embedded system, any other suitable computing device, or any combination thereof, with programmed instructions to determine where the solder joints on the battery cell should be located. Such processing may include, for example, any suitable computer vision technology.

[0060] Welding apparatus 706 includes any suitable hardware, software, or both for performing welding operations in response to and in accordance with welding control signal 710. Example welding apparatus may include a laser welding apparatus configured to generate a beam for propagating micro-solder joints (e.g., micro-solder joint 120). However, other welding apparatus may be used, such as metal welding apparatus, any other suitable welding apparatus, or any combination thereof. Processing circuitry 704 may provide information directly to welding apparatus 706 to allow welding apparatus 706 to, for example, fine-tune the position for placing the solder joint. Welding apparatus 706 may include any suitable automated moving / robotic device for moving appropriate means to perform the desired weld. Given instructions to cause the laser to follow a path for forming micro-solder joint 120 may, by way of example only, include instructions for the starting point of the laser where the micro-solder joint 120 (e.g., endpoint 121) begins, the length of line segment 123 of the micro-solder joint 120 formed by the laser, or instructions for the endpoint 121 of the micro-solder joint 120. The instructions may also include the spacing between laterally adjacent solder joints 120, such as the distance D between solder joints 120. Furthermore, the instructions may include the order in which the solder joints 120 are formed, such as the positions of the first solder joint 120 and subsequent solder joints 120.

[0061] Turn now Figure 8 An example process 800 for welding one or more welding zones is shown and described in further detail. In one example, process 800 may be performed by processing circuitry 704 or welding equipment 706.

[0062] Process 800 may begin at block 805, where a count variable is used to form micro-solder joints. Typically, process 800 forms the first micro-solder joint and continues to form up to a desired number of micro-solder joints. n Additional micro-solder joints. Process 800 can initially count variables. n Set to an integer one (1). Then, process 800 can proceed to box 810.

[0063] At box 810, process 800 can determine the first... n The location or positioning of each micro-weld point. As described above, in some example methods, the first micro-weld point 120 of the weld begins in the middle or central region (e.g., the central portion 150 of weld 116), and subsequent micro-weld points begin alternately on either side of the first micro-weld point 120. The process 800 can then proceed to frame 815.

[0064] At box 815, the laser can be moved to form the first... nThe location of each micro-weld point. For example, the laser can be moved to a desired location as defined in frame 810. In some examples, the laser is moved to, for example, the shoulder of a cylindrical battery cell. In another example, the laser is moved to a first portion of battery cell 102 to micro-weld a first segment.

[0065] Proceeding to box 820, process 800 can begin welding the nth weld point in the selected welding area. In at least some examples, processing circuitry 704 generates a welding control signal based on the selected welding area. In some embodiments, the welding control signal includes an analog signal. For example, the voltage, current, frequency, or other suitable characteristics of the welding control signal may indicate one or more welding parameters (e.g., current, duration, or other suitable parameters). In some embodiments, the welding control signal includes a digital signal. For example, the welding control signal may include a message, value, set of values, or other suitable information indicating one or more welding parameters (e.g., current, duration, or other suitable parameters). Processing circuitry 704 may also transmit the welding control signal to welding equipment 706, thereby causing welding equipment 706 to perform welding, for example, as micro-weld point 120. Processing circuitry 704 may use any suitable communication network (e.g., wired, wireless, or optical) and protocol to generate and transmit the welding control signal.

[0066] As discussed above, in some example methods, the micro-solder point 120 begins with a solderless region 122 surrounding it. As mentioned above, in some examples, the solderless region may extend around the periphery (e.g., the entire periphery) of the micro-solder point 120. As mentioned above, the micro-solder point 120 may be elongated or formed as a line such that once formed, the micro-solder point 120 is surrounded by the solderless region 122. As an example only, as mentioned above, the example micro-solder point 120 may extend across a relatively narrow (e.g., approximately 700 micrometers wide) shoulder region 111 of the battery cell 102. Furthermore, applying the micro-solder point 120 as a line can be a conductive solder point and can avoid over-penetration of the solder area or the formation of "keyhole" solder points. Therefore, the depth of the solder point may be less than the maximum thickness of the terminal substrate of the solder point (e.g., the lower contact of the battery cell 102). By avoiding excessive penetration of the weld seam through the micro-solder joints 120, damage to the underlying insulation of unit 102 (e.g., the insulation material 107 as discussed above) can be reduced or eliminated.

[0067] Then, process 800 can proceed to box 825, where process 800 queries whether the soldering area has been completed. In the example of forming multiple solder joints 120 (e.g., weld 116), after forming the first micro-solder joint 120, process 800 will proceed to box 830 where the count variable n is incremented, and then can proceed to box 810. Thus, process 800 can determine the position and begin each subsequent micro-solder joint 120 (e.g., second micro-solder joint, third micro-solder joint, fourth, etc.) until the desired number of micro-solder joints n.

[0068] It should be noted that subsequent weld points 120 formed in the weld (e.g., weld 116) can be located and initiated in any convenient manner. As described above, in some example methods, an initial micro-weld point 120 is formed in the middle or generally central portion of the weld 116, wherein subsequent weld points 120 are formed alternately on either side of the first micro-weld point 120. Each subsequent micro-weld point 120 may have a corresponding unwelded area 122 formed around the micro-weld point 120. In some examples, a plurality of micro-weld points 120 may be formed, which are laterally adjacent and spaced apart by their respective unwelded areas 122. Furthermore, in some examples, the micro-weld points 120 may be longitudinally offset relative to their adjacent micro-weld points 120. The longitudinal offset of the micro-weld points 120 may facilitate the weld 114 and / or weld 116 along a non-straight surface, such as a curved surface or a circular surface, or provide a parallelogram shape, as described above. Figure 5 As shown in the diagram. The longitudinally offset micro-solder joint 120 may be convenient for substrates with curved surfaces (e.g., the shoulder region 111 of cylindrical unit 102). The solder area can be other shapes, for example, as described above. Figure 4 The shapes shown are usually rectangular, square, etc.

[0069] Process 800 can be exemplified by determining, at box 830, that the welded area is complete based on the expected number of solder joints x in a given welded area being equal to the count integer n. Then, process 800 can be terminated.

[0070] It should be noted that process 800 can be employed in the context of a battery pack welding process, wherein multiple positive contacts / terminals are micro-welded together in multiple passes, and multiple negative contacts / terminals are micro-welded together in multiple passes. For example, as detailed above, in the example welding process, the first pass may begin laser welding on a first side of a row of positive terminals 104 and associated positive contacts 106. A second pass of the laser may subsequently begin laser welding at another location of each of the positive terminals 104 / positive contacts 106. Negative contacts and negative terminals may be connected in a similar multi-pass manner. More specifically, also as described above, the first pass may begin laser welding on a first side of a row of negative terminals 105 and associated negative contacts 110. A second pass of the laser may subsequently begin laser welding at another location of each of the negative terminals 105 / negative contacts 110.

[0071] Refer again Figure 5 and Figure 8 For use in forming Figure 5 The example embodiment of process 800 for the example weld 116 shown is described in further detail. As described above, Figure 5 The example weld 116 shown includes twelve (12) different micro-weld points 120a-l, each formed with a different line segment 123a-l. Each segment 123 extends between a corresponding radially outer endpoint 121a and a radially inner endpoint 121b. Also as described above, the weld 116 and each of its micro-weld points 120 can be positioned on the shoulder of the battery cell, for example, in different portions 150, 152, 154 of the cylindrical battery cell 102. Therefore, the desired number of micro-weld points x can be set to 12. As described above, the process 800 can initially set the count integer n to the integer one.

[0072] Proceeding to frame 810, the position of the nth / first micro-solder point (i.e., micro-solder point 120a) is determined. As described above, each micro-solder point 120 can be formed as a line segment 123, and can be formed sequentially such that one or more centrally located micro-solder points (e.g., micro-solder point 120a) are initially formed within the central portion 150 of the weld 116. Subsequently, additional micro-solder points 120 can be formed on each side of the initial micro-solder point 120a and on different portions 152 / 154, for example by alternating between different sides of the initial micro-solder point 120a and / or between different portions 152 / 154 of the battery cell 102. Thus, at frame 810, process 800 can determine the starting position corresponding to micro-solder point 120a, for example, the radially outer endpoint 121a of line segment 123a.

[0073] Proceeding to frame 815, for example, the welding laser of welding equipment 706 can be moved to the position defined at frame 810. Therefore, process 800 can move the welding laser to the radially outer endpoint 121a of line segment 123a. At frame 820, process 820 can turn on the laser and form a micro-solder joint 120a by moving the laser along the first line segment 123a from endpoint 121a to endpoint 121b. When the laser reaches endpoint 121b, the laser can be turned off to complete the micro-solder joint 120a. Additionally, as described above, the micro-solder joint 120a may have a weld-free area 122a extending around its periphery or surrounding the micro-solder joint 120a. Then, process 800 can proceed to frame 825.

[0074] At box 825, process 800 checks whether weld 116 is complete. Since additional micro-welds 120 (i.e., micro-welds 120b-l) are still to be formed, process 800 then proceeds to box 830, where the count integer n is incremented (i.e., incremented to two (2)). Then, process 800 proceeds to box 810.

[0075] At block 810, process 800 determines the position of the second (i.e., n=2) micro-solder point 120b. As described above, the micro-solder point 120b can be formed as a line segment 123b extending between its radially outer endpoint 121a and its radially inner endpoint 121b. The line segment 123b is located in a different part of the battery cell, i.e., in part 154. Furthermore, in this example, i.e., by moving the laser from the radially inner endpoint 121b of the micro-solder point 120b to the radially outer endpoint 121a, the micro-solder point 120b is formed in the opposite direction to the previous micro-solder point 120a, but other directions or methods may also be used. Therefore, the position can be determined at block 810 as the radially inner endpoint 121b of the micro-solder point 120b.

[0076] Moving to frame 815 allows the laser to be moved to the position defined at frame 810. Thus, upon completion of a previous micro-solder joint 120a, the laser can move, for example, a distance D in response to being switched off. As described above, micro-solder joint 120b can be spaced apart from micro-solder joint 120a by a distance D. Therefore, movement of the welding laser of the welding apparatus 706 at frame 815 can include moving the laser a distance D, for example, from the radially inner endpoint 121b of line segment 123a to the radially inner endpoint 121b of line segment 123b. As described above, micro-solder joint 120a is located in the central portion 150 of the weld 116 on the battery cell 102, and therefore the laser can move from portion 150 to different portions 154 of the battery cell 102 to reach line segment 123b. Therefore, in some examples, when forming different micro-solder joints 120, movement of the laser can cause the laser to move between different portions of the battery cell 102.

[0077] In response to the welding laser of welding equipment 706 moving to a determined position, for example by moving the laser a distance D, process 800 can advance to micro-welding segment 123b at frame 820. For example, using a welding laser positioned at the radially inner endpoint 121b of segment 123b, the welding laser can be turned on and subsequently moved along segment 123b. When the radially outer endpoint 121a of segment 123b is reached, the welding laser can be turned off, thereby forming micro-weld 120b. Furthermore, a weld-free area 122b surrounding segment 123b / micro-weld 120b can be maintained. Process 800 can then advance to frame 825.

[0078] At frame 825, process 800 determines that the weld is incomplete because micro-weld joint 120c-l still needs to be formed. Therefore, process 800 proceeds to frame 830 to increment n, and then proceeds to frame 810.

[0079] At block 810, process 800 determines the position of the third (i.e., n=3) micro-solder point 120c. As described above, micro-solder point 120c can be formed as a line segment 123c extending between its radially outer endpoint 121a and its radially inner endpoint 121b. In this example, that is, by moving the laser from the radially outer endpoint 121a of the line segment 123c to the radially inner endpoint 121b, micro-solder point 120c is formed in the opposite direction to the previous micro-solder point 120b. Furthermore, the direction of movement of the welding laser when forming micro-solder point 120c can be the same as when forming micro-solder point 120a, that is, radially inward along the shoulder of battery cell 102. Other directions or methods can also be used. Therefore, the position can be determined at block 810 as the radially outer endpoint 121a of the line segment 123c.

[0080] Moving to frame 815, the laser can be moved to the position defined at frame 810. As described above, micro-solder point 120c can be spaced apart from micro-solder point 120a by a distance D and can be positioned on the side of micro-solder point 120a opposite to micro-solder point 120b. Therefore, the movement of the welding laser of the welding apparatus 706 at frame 815 can include moving the laser a plurality of distances D (e.g., twice the distance D), corresponding to the distance from the radially outer endpoint 121a of line segment 123b to the radially outer endpoint 121a of line segment 123c. Line segment 123c is shown as being positioned in a different portion 152 of the battery cell 102, different from micro-solder point 120a (which is within the central portion 150) and micro-solder point 120b (which is within portion 154). Therefore, the welding laser can be moved from portion 154 of the battery cell 102 to a different portion, namely portion 152 at frame 815.

[0081] In response to the welding laser of welding equipment 706 moving to a determined position, for example by moving the laser to the radially outer endpoint 121a of line segment 123c, process 800 can proceed to micro-welding line segment 123c at frame 820. For example, using a welding laser positioned at the radially outer endpoint 121a of line segment 123c, the welding laser can be turned on and subsequently moved along line segment 123c to the radially inner endpoint 121b. When the radially inner endpoint 121b of line segment 123c is reached, the welding laser can be turned off, thereby forming a micro-weld point 120c. Furthermore, a weld-free area 122c surrounding line segment 123c / micro-weld point 120c can be maintained. As described above, the second formed micro-weld point 120b and the third formed micro-weld point 120c are on opposite sides of the first formed micro-weld point 120a, and therefore, line segment 123b and line segment 123c are also on opposite sides of line segment 123a of the first formed micro-weld point 120a. Then, process 800 can proceed to box 825.

[0082] At frame 825, process 800 determines that the weld is incomplete because micro-weld joint 120d-l still needs to be formed. Therefore, process 800 proceeds to frame 830 to increment n, and then proceeds to frame 810.

[0083] Process 800 can continue to cycle through boxes 810 to 830, along... Figure 5 The corresponding line segments 123 shown form the fourth micro-solder point 120d, the fifth micro-solder point 120e, and so on. Process 800 can eventually form the twelfth micro-solder point 120l, where the count integer n advances to the integer twelve (12). Therefore, process 800 can determine the completion of the weld 16 at block 825 because the count integer n is equal to the desired number of micro-solder points x. As mentioned above, in other example methods, different numbers of micro-solder points 120 can be implemented to form a weld between, for example, the contacts and the shoulder of the battery cell 102.

[0084] As described above, in the example weld 116, each segment 123 of the micro-weld point 120 extends parallel to each other. Furthermore, each segment 123 is laterally spaced by the same distance D, which extends in a direction perpendicular to the first segment 123a. Furthermore, as described above, in Figure 5 In the example shown, the length of each line segment 123 of the micro-weld point 120 in weld 116 does not exceed 700 micrometers.

[0085] The foregoing description includes exemplary embodiments according to this disclosure. These examples are provided for illustrative purposes only and not for limiting purposes. It should be understood that this disclosure may be implemented in different forms than those expressly described and shown herein, and various modifications, optimizations, and variations accorded to the following claims can be implemented by those skilled in the art.

Claims

1. A method for micro-welding battery terminals, the method comprising: Move the laser to the shoulder of the battery cell; The laser is used to micro-weld a first line segment onto the shoulder of the battery cell; The laser is moved a certain distance on the shoulder of the battery cell in a direction perpendicular to the first line segment; In response to moving the laser by the distance, a second segment is micro-welded parallel to the first segment on the shoulder of the battery cell using the laser; A first weld-free zone is formed around the first line segment; as well as A second weld-free zone is formed around the second line segment. Each of the first and second line segments is elongated, such that each segment has a width less than its length and has two endpoints along its extension direction. The first line segment and the second line segment form a weld between the contact and the shoulder of the battery cell. The length of each of the first and second line segments does not exceed 700 micrometers.

2. The method according to claim 1, wherein, The distance includes a predetermined distance, and the method further includes: Turn on the laser to micro-weld the first line segment; The laser is turned off before it is moved the predetermined distance; In response to moving the laser by the predetermined distance, the laser is turned on to micro-weld the second line segment.

3. The method according to claim 2, wherein the method further comprises: After micro-welding the second segment, the laser is turned off; In response to shutting down the laser, the laser is moved a plurality of the predetermined distances from the second line segment; In response to moving the laser by the plurality of predetermined distances, the laser is activated to micro-weld the third line segment.

4. The method according to claim 1, wherein, Moving the laser to the shoulder of the battery cell includes moving the laser to a first portion of the battery cell to micro-weld the first line segment; and Moving the laser a certain distance on the shoulder of the battery cell in a direction perpendicular to the first line segment includes moving the laser a certain distance to a second part of the battery cell to micro-weld the second line segment.

5. The method according to claim 4, wherein the method further comprises: Move the laser from the second part to the third part of the battery cell; as well as In response to moving the laser from the second part to the third part, the third segment is micro-welded.

6. The method according to claim 5, wherein, The second line segment and the third line segment are on opposite sides of the first line segment.

7. The method according to claim 6, wherein, The first line segment is formed in the central part of the weld.

8. The method according to claim 1, wherein, The battery unit is cylindrical.

9. A battery cell assembly, the battery cell assembly comprising: Battery cell; At least one weld seam is provided on the shoulder of the battery cell, wherein each weld seam comprises a first micro-welded segment and a second micro-welded segment that are spaced apart and adjacent to each other. The first micro-welding segment and the second micro-welding segment are parallel to each other. Each of the first and second micro-welding segments is elongated, such that each micro-welding segment has a width less than its length and two endpoints along its extension direction. Wherein, the distance is perpendicular to the first micro-welding segment and the second micro-welding segment. The first weld-free area surrounds the first micro-welded segment, and the second weld-free area surrounds the second micro-welded segment. The length of each of the first micro-welding segment and the second micro-welding segment does not exceed 700 micrometers.

10. A battery pack, the battery pack comprising: Multiple battery cells; Multiple weld seams, each battery cell having at least one weld seam on its shoulder, each weld seam comprising a first micro-welded segment and a second micro-welded segment spaced apart and adjacent to each other. The first micro-welding segment and the second micro-welding segment are parallel to each other. Each of the first and second micro-welding segments is elongated, such that each micro-welding segment has a width less than its length and two endpoints along its extension direction. Wherein, the distance is perpendicular to the first micro-welding segment and the second micro-welding segment. The first weld-free area surrounds the first micro-welded segment, and the second weld-free area surrounds the second micro-welded segment. The length of each of the first micro-welding segment and the second micro-welding segment does not exceed 700 micrometers.

11. The battery pack of claim 10, further comprising a negative contact connected to the battery cell via the weld.

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