Single battery and welding auxiliary tool

Abstract

The utility model provides a single battery and a welding auxiliary tool, and the single battery comprises a cover plate assembly which is provided with a pole; the shell is connected with the cover plate assembly to form an accommodating cavity; the electrode assembly is positioned in the accommodating cavity; the protection sheets are provided with a plurality of spot-shaped welding marks which are formed by laser welding and are distributed at intervals, a pole and a tab of the electrode assembly, the protection sheets are connected through the plurality of spot-shaped welding marks, and the protection sheets are positioned on one side, far away from the pole, of the tab; according to the invention, the ultrasonic pre-welding process of the tab can be omitted, and the formation of splash is avoided; meanwhile, the welding area between the two is reduced, so that the direct-current impedance of the single battery is reduced, and the safety performance of the single battery is improved.

Description

Technical Field

[0001] This application relates to the field of battery cell technology, and in particular to a single-cell battery and a welding auxiliary tool. Background Technology

[0002] Square-shell cells are a common type of single-cell battery.

[0003] In related technologies, ultrasonic welding is typically used to pre-weld the stacked tabs before connecting them directly to the terminals of the cover plate assembly or via adapter plates. However, ultrasonic welding generates spatter, which becomes foreign matter and increases the safety risks of individual cells. Utility Model Content

[0004] In view of this, the present application aims to provide a single cell and a welding auxiliary tool to solve some or all of the above-mentioned technical problems.

[0005] For the purposes described above, a first aspect of this application provides a single-cell battery, comprising:

[0006] A cover plate assembly, wherein the cover plate assembly is provided with pole posts;

[0007] A housing, which is connected to the cover assembly to form a receiving cavity;

[0008] An electrode assembly located within the receiving cavity;

[0009] The protective sheet has multiple spaced dot-shaped weld marks formed by laser welding. The electrode post, the electrode tab of the electrode assembly, and the protective sheet are connected by the multiple dot-shaped weld marks. The protective sheet is located on the side of the electrode tab away from the electrode post.

[0010] Optionally, a plurality of the dot-shaped solder marks are arranged in the protective sheet array, and the distance between two adjacent dot-shaped solder marks is greater than or equal to 1.5 mm.

[0011] Optionally, the dotted solder mark is circular, and the diameter of the dotted solder mark is 1.5 mm to 3.5 mm; or,

[0012] The dotted solder mark can be either square or rhomboid, and the diagonal length of the dotted solder mark is between 1.5mm and 3.5mm.

[0013] Optionally, the plurality of the dotted solder marks form at least one welding area within the surface of the protective sheet, the shape of the welding area matching the shape of the side of the pole away from the cover plate assembly;

[0014] The welding area can be one of the following: circular, semi-circular, elliptical, or polygonal.

[0015] Optionally, a plurality of the dotted solder marks form a welding area within the surface of the protective sheet, wherein the minimum distance between the edge of the welding area and the edge of the protective sheet is less than or equal to 2 mm.

[0016] Optionally, a plurality of the dotted solder marks form a welding area within the surface of the protective sheet, wherein the ratio of the area of ​​the welding area to the area of ​​the tab is 10% to 60%.

[0017] A second aspect of this application provides a welding aid tool suitable for assisting in the welding of single-cell batteries as described in the first aspect, the welding aid tool comprising:

[0018] The welding auxiliary tool is provided with a laser input end and a laser output end at opposite ends;

[0019] The emission end is used to abut against the surface of the protective sheet away from the cover plate assembly during laser welding, so as to press the protective sheet and the electrode tab tightly against the surface of the electrode post through the emission end.

[0020] Optionally, the emission end includes an outer frame and a grid disposed inside the outer frame, the grid having multiple grid holes for the laser to pass through.

[0021] The surface of the grille away from the incident end is flush with the surface of the exit end away from the incident end.

[0022] Optionally, the welding auxiliary tool is further provided with a protective gas release channel, and a laser channel is formed between the incident end and the exit end.

[0023] The protective gas release channel is connected to the laser channel;

[0024] One of the two ports of the protective gas release channel is located at the incident end, and the other is located on the inner wall of the laser channel.

[0025] Optionally, the area of ​​the ejector end is less than or equal to the area of ​​the protective sheet, and the ejector end is located within the protective sheet during the welding process.

[0026] As can be seen from the above, the single cell and welding auxiliary tool provided in this application connect the terminal, tab and protective sheet of the single cell through multiple spaced dot-shaped weld marks formed by laser, which can eliminate the ultrasonic pre-welding process of the tab and avoid the formation of spatter; and the multiple dot-shaped weld marks can ensure the connection quality between the tab and the terminal, reduce the welding area formed between the two, reduce the DC resistance of the single cell, and thus improve the safety performance of the single cell. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a single battery cell;

[0029] Figure 2 This is a schematic diagram showing the connection between the cover plate assembly and an electrode assembly.

[0030] Figure 3 This is a schematic diagram showing the connection between the pole post and the pole tab;

[0031] Figure 4 A bottom view of the welding auxiliary tools;

[0032] Figure 5 Top view of welding auxiliary tools;

[0033] Figure 6 A side view of the welding auxiliary tools;

[0034] Figure 7 This is a top view of the electrode assembly and cover plate assembly during welding.

[0035] Figure 8 An oblique axonometric view of the electrode assembly and cover plate assembly under welding conditions;

[0036] Figure 9 A schematic diagram illustrating the welding of the pole post and the pole tab using welding auxiliary tools;

[0037] Figure 10 This is an exploded view of the cover plate assembly, electrode assembly, and welding auxiliary tools.

[0038] Explanation of reference numerals in the attached figures:

[0039] 10-1, Cover plate assembly; 10-1-1, Terminal post; 10-1-2, Plastic parts;

[0040] 10-2, Electrode assembly; 10-2-1, Tab;

[0041] 10-3, Protective sheet; 10-3-1, Dotted solder marks;

[0042] 10-4. Shell;

[0043] 20-1 Welding auxiliary tools; 20-1-1 Injection end; 20-1-2 Exit end; 20-1-2-1 Outer frame; 20-1-2-2 Grating; 20-1-2-2-1 Grating holes; 20-1-3 Laser channel;

[0044] 20-2, Protective gas release channel. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0046] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0047] A typical prismatic cell includes a cover plate assembly, a casing, and an electrode assembly. The electrode assembly has multiple tabs extending outwards, which are electrically connected to the terminals on the cover plate assembly. Currently, the industry commonly uses ultrasonic welding technology to pre-weld the stacked tabs. This involves using the heat generated by mechanical vibration to pre-connect the tabs, and then connecting the pre-welded tabs directly to the terminals of the cover plate assembly or via adapter plates to achieve electrical connection between the tabs and terminals.

[0048] However, the applicant discovered that the application of ultrasonic welding technology in practical applications also has many drawbacks that limit the performance of individual cells. Specifically, firstly, because ultrasonic welding technology uses high-frequency amplitude to perform welding, it generates spatter. If the spatter becomes a foreign object and enters the individual cell, it may cause internal short circuits or other forms of failure, increasing the risk of abnormality and threatening the stability and safety of the individual cell.

[0049] This application provides a single-cell battery, including a cover plate assembly 10-1, an electrode assembly 10-2, a protective sheet 10-3, and a casing 10-4, combined with... Figures 1-3 The content shown illustrates the single-cell battery provided in this application.

[0050] A single-cell battery includes a cover plate assembly 10-1, an electrode assembly 10-2, a protective sheet 10-3, and a housing 10-4. The cover plate assembly 10-1 is connected to the housing 10-4, and the inner surface of the cover plate assembly 10-1 and the inner surface of the housing 10-4 form a receiving cavity, within which the electrode assembly 10-2 is located. The cover plate assembly 10-1 is provided with a terminal post 10-1-1, and the electrode assembly 10-2 extends a tab 10-2-1 on the side near the terminal post 10-1-1. The protective sheet 10-3 has a plurality of spaced dot-shaped weld marks 10-3-1 formed by laser welding. The terminal post 10-1-1, the tab 10-2-1 of the electrode assembly 10-2, and the protective sheet 10-3 are connected through the plurality of dot-shaped weld marks 10-3-1, with the protective sheet 10-3 located on the side of the tab 10-2-1 away from the terminal post 10-1-1.

[0051] Specifically, Figure 1 This is a schematic diagram of a single battery cell. Figure 2 This is a schematic diagram showing the connection between the cover plate assembly and an electrode assembly 10-2. Figure 3 This is a schematic diagram showing the connection between pole post 10-1-1 and pole tab 10-2-1.

[0052] For cover plate assembly 10-1, such as Figure 1 and Figure 2 As shown, the cover plate assembly 10-1 is used to seal the housing 10-4 to isolate the internal and external environments of the individual battery cells and ensure the stability of the battery. The cover plate assembly 10-1 is provided with a terminal post 10-1-1. The post of the terminal post 10-1-1 penetrates the cover plate assembly 10-1 and extends to the outer surface of the cover plate assembly 10-1 to establish an electrical connection with external devices. The connecting part of the terminal post 10-1-1 can be integrally formed with the post and located in the receiving cavity to establish a connection with the tab 10-2-1.

[0053] Furthermore, the cover assembly 10-1 is equipped with an explosion-proof valve, which can be opened when a single cell experiences thermal runaway, to promptly eject the high-temperature and high-pressure gas generated inside the containment cavity, as well as ejected materials containing solid or gel-like substances, thereby improving the safety of the single cell.

[0054] Furthermore, the cover plate assembly 10-1 may be provided with an injection hole, through which electrolyte can be injected into the receiving cavity to ensure the performance of the single cell.

[0055] Furthermore, the terminals 10-1-1 of a single cell may include a positive terminal and a negative terminal.

[0056] For electrode components, such as Figures 1-3As shown, the electrode assembly 10-2 includes a stacked and wound positive electrode, a negative electrode, and a separator. The positive electrode and the negative electrode are electrically connected to the positive electrode post and the negative electrode post respectively through the tabs 10-2-1, and store and release energy through chemical reactions. The separator is used to physically isolate the positive electrode and the negative electrode and allows ions in the electrolyte to migrate freely during charging and discharging, while also preventing the positive electrode and the negative electrode from contacting each other and causing a short circuit.

[0057] For protective film 10-3, such as Figures 1-3 As shown, the protective sheet 10-3 is located on the side of the tab 10-2-1 away from the terminal post 10-1-1, ensuring that the protective sheet 10-3 covers at least part of the overlapping area between the terminal post 10-1-1 and the tab 10-2-1. This helps to improve the welding strength between the terminal post 10-1-1 and the tab 10-2-1, avoids cracking or falling off under severe working conditions such as external impact or vibration, and helps to ensure the overall performance of the single cell.

[0058] Furthermore, one of the apex corners of the protective sheet 10-3 can be removed to form a foolproof chamfer, which can be used as an assembly mark to improve the assembly efficiency and accuracy of the protective sheet 10-3, and help reduce the assembly difficulty and error rate of the protective sheet 10-3.

[0059] Furthermore, the protective plate 10-3 can be configured according to the type and material of the terminal 1-1-1; for example, the protective plate 10-3 corresponding to the positive terminal can be made of aluminum, and the protective plate 10-3 corresponding to the positive terminal can be made of copper, which will not be elaborated here.

[0060] For dotted solder marks 10-3-1, such as Figures 1-3 As shown, multiple dot-shaped weld marks 10-3-1 can be formed using laser spot welding technology. Specifically, during the welding process, the stacked tabs 10-2-1 and the protective sheet 10-3 can be placed on the connecting surface of the terminal post 10-1-1. Then, dot-shaped weld marks 10-3-1 are formed within the protective sheet 10-3 using laser welding technology. These dot-shaped weld marks 10-3-1 fix the protective sheet 10-3 and the tabs 10-2-1 to the terminal post 10-1-1, meaning the tabs 10-2-1 are directly welded to the terminal post 10-1-1 using the dot-shaped weld marks 10-3-1 formed by laser welding. Therefore, compared to the original assembly process, the ultrasonic pre-welding process of the tabs 10-2-1 can be eliminated, thus preventing the formation of spatter and foreign matter, thereby reducing the application risk of the single-cell battery and ensuring its safety in use.

[0061] More specifically, such as Figures 1-3As shown, after welding, the tab 10-2-1 and the post 10-1-1 are fixedly connected by multiple dot-shaped weld marks 10-3-1. By using multiple spaced dot-shaped weld marks 10-3-1, the connection area formed by the weld marks between the tab 10-2-1 and the post 10-1-1 can be increased to ensure the connection effect between the two. At the same time, since there are gaps between adjacent dot-shaped weld marks 10-3-1, the actual welding area between the tab 10-2-1 and the post 10-1-1 can be reduced, which can reduce the excessive heat accumulation during laser welding and prevent damage to the plastic part 10-1-2 in the cover plate assembly 10-1.

[0062] In some embodiments, a plurality of dot-shaped solder marks 10-3-1 are arranged in an array on the protective sheet 10-3, and the distance between two adjacent dot-shaped solder marks 10-3-1 is greater than or equal to 1.5 mm.

[0063] For example, the distance between two adjacent spot welds 10-3-1 can be ≥1.5mm (e.g., 1.5mm, 1.7mm or 2.0mm); when the distance between two adjacent spot welds 10-3-1 is 1.5mm, the heat-affected zone of the two adjacent spot welds 10-3-1 can be reduced, avoiding the situation of weld burn-through due to heat accumulation between adjacent spot welds 10-3-1 during the welding process, and also reducing the heat-affected zone of the cover plate assembly 10-1.

[0064] Furthermore, by setting the distance between the two dot-shaped solder marks 10-3-1 to 1.5mm, multiple dot-shaped solder marks 10-3-1 can form a larger connection area, thereby ensuring the connection quality between the pole post 10-1-1 and the tab 10-2-1.

[0065] In some embodiments, the dotted solder mark 10-3-1 can be circular, with a diameter of 1.5mm to 3.5mm; or the dotted solder mark 10-3-1 can be square or rhomboid, with a diagonal length of 1.5mm to 3.5mm. That is, for the dotted solder mark 10-3-1, such as... Figure 2 and Figure 3 As shown, the dotted solder mark 10-3-1 can be circular, elliptical, or other shapes. All of these shapes can achieve the purpose of controlling the welding area between the barrier tab 10-2-1 and the pole post 10-1-1, and ensuring the connection strength between the two.

[0066] For example, when the dotted weld mark 10-3-1 is circular, the heat distribution of the dotted weld mark 10-3-1 is uniform and easy to form, so the welding quality is relatively stable and the heat-affected zone is relatively small. Furthermore, the diameter of the circular dotted weld mark 10-3-1 can be 1.5-3.5mm (e.g., 1.5mm, 2.5mm or 3.5mm), which can increase the density of the dotted weld mark 10-3-1 distribution, so as to ensure the connection quality between the pole post 10-1-1 and the tab 10-2-1, while also preventing the plastic part 10-1-2 of the cover plate assembly 10-1 from melting.

[0067] For example, when the dotted weld mark 10-3-1 is square, the structure of the dotted weld mark 10-3-1 is relatively regular, and the strength of the welding area formed by the dotted weld mark 10-3-1 is also relatively high. Furthermore, the diagonal length of the dotted weld mark 10-3-1 can be set to 1.5-3.5mm (e.g., 1.5mm, 2.5mm, or 3.5mm), which can increase the density of the distribution of the dotted weld mark 10-3-1, ensuring the connection quality between the pole post 10-1-1 and the tab 10-2-1, while also preventing the plastic part 10-1-2 of the cover plate assembly 10-1 from melting.

[0068] In some embodiments, a plurality of dot-shaped solder marks 10-3-1 form at least one welding area in the surface of the protective sheet 10-3. The shape of the welding area is adapted to the end face of the pole post 10-1-1 near the electrode assembly 10-2, that is, the connection part of the pole post 10-1-1 is adapted to the welding area; wherein, the welding area is one of the following: circular, semi-circular, elliptical and polygonal.

[0069] Specifically, since multiple dot-shaped solder marks 10-3-1 can form at least one welding area within the protective sheet 10-3, by matching the shape of the welding area with the surface shape of the pole post 10-1-1 away from the cover plate assembly 10-1, the forming area of ​​the welding area within the pole post 10-1-1 can be increased, and the proportion of the welding area to the surface of the pole post 10-1-1 can be increased, thereby improving the connection effect between the pole post 10-1-1 and the tab 10-2-1.

[0070] For example, the welding area is one of a circle, a semi-circle, an ellipse, and a polygon, and matches the surface shape of the pole post 10-1-1 away from the cover plate assembly 10-1; for example, as Figures 2-3 As shown, when the connecting part of the pole post 10-1-1 is square, the welding area formed by multiple dot-shaped solder marks 10-3-1 can be square, so that it can be adapted to the surface of the pole post 10-1-1. For example, when the connecting part of the pole post 10-1-1 is circular, the welding area formed by multiple dot-shaped solder marks 10-3-1 can be circular.

[0071] In some embodiments, a plurality of dot-shaped solder marks 10-3-1 form a welding area within the surface of the protective sheet 10-3, and the minimum distance between the edge of the welding area and the edge of the protective sheet 10-3 is less than or equal to 2 mm.

[0072] Specifically, for the welding area, by ensuring that the distance between the edge of the welding area and the edge of the protective sheet 10-3 is less than or equal to 2 mm (e.g., 1 mm, 1.5 mm, or 2 mm), it is ensured that the multiple point weld marks 10-3-1 forming the welding area are all located within the protective sheet 10-3, so that each point weld mark 10-3-1 can be at the connection point of the pole post 10-1-1 and the tab 10-2-1, thereby ensuring the connection strength between the pole post 10-1-1, the tab 10-2-1, and the protective sheet 10-3.

[0073] In some embodiments, a plurality of dotted solder marks 10-3-1 form a welding area within the surface of the protective sheet 10-3, and the ratio of the area of ​​the welding area to the area of ​​the tab 10-2-1 is 10% to 60%.

[0074] Specifically, for the welding area, when the ratio of the area of ​​the welding area to the area of ​​the tab 10-2-1 is greater than 10%, the connection area between the post 10-1-1 and the tab 10-2-1 can be increased to ensure good connection strength between the two. When the ratio of the area of ​​the welding area to the area of ​​the tab 10-2-1 is less than 60%, sufficient bending allowance can be reserved for the tab 10-2-1 to ensure that the electrode assembly 10-2 can be smoothly assembled into the casing of the single cell.

[0075] In addition, this application also provides a welding aid tool 20-1, which can reduce the possibility of incomplete soldering and is suitable for assisting in the welding of single cells described in any of the above embodiments. Figures 4-10 The welding auxiliary tool 20-1 is described in detail.

[0076] The welding auxiliary tool 20-1 has a laser incident end 20-1-1 and an exit end 20-1-2 at opposite ends. During the laser welding process, the exit end 20-1-2 is used to press the protective plate 10-3 away from the surface of the cover plate assembly 10-1, and press the protective plate 10-3 and the electrode tab 10-2-1 onto the surface of the electrode post 10-1-1.

[0077] Specifically, Figures 4-6 These are the bottom view, top view, and side view of welding auxiliary tool 20-1. Figure 7 This is an oblique axonometric view of electrode assembly 10-2 and cover plate assembly 10-1 under welding conditions. Figure 8 This is a top view of electrode assembly 10-2 and cover plate assembly 10-1 in the welding process. Figure 9This is a schematic diagram of the connection between pole post 10-1-1 and pole lug 10-2-1 in the welded state. Figure 10 Exploded view of cover plate assembly 10-1, electrode assembly 10-2 and welding auxiliary tool 20-1.

[0078] This application also provides a welding auxiliary tool 20-1 for improving the connection effect between the electrode post 10-1-1, the electrode tab 10-2-1, and the protective sheet 10-3 during the welding process. This welding auxiliary tool is suitable for assisting in the welding of single-cell batteries described in any of the above embodiments. Specifically, for the welding auxiliary tool 20-1, such as... Figures 4-6 As shown, the welding auxiliary tool 20-1 has a laser incident end 20-1-1 and an exit end 20-1-2 at opposite ends. During the welding process, the laser enters the welding auxiliary tool 20-1 from the incident end 20-1-1 and exits from the welding auxiliary tool 20-1 from the exit end 20-1-2, acting on the protective plate 10-3. The high energy of the laser is used to weld the pole post 10-1-1, the tab 10-2-1 and the protective plate 10-3.

[0079] For example, the welding aid 20-1 may be formed of a material such as copper or a copper alloy. In one example, the welding aid 20-1 may be a nozzle, and further, the welding aid 20-1 may be a copper nozzle.

[0080] More specifically, such as Figures 7-10 As shown, when welding with welding auxiliary tool 20-1, the ejector end 20-1-2 of welding auxiliary tool 20-1 abuts against the surface of protective plate 10-3 away from cover plate assembly 10-1. The ejector end 20-1-2 of welding auxiliary tool 20-1 can press protective plate 10-3 and tab 10-2-1 onto the surface of pole post 10-1-1, so that protective plate 10-3 and tab 10-2-1, and pole post 10-1-1 and tab 10-2-1 are in full contact, to ensure that pole post 10-1-1, tab 10-2-1 and protective plate 10-3 have good compactness after welding, reduce the DCR (Direct Current Resistance) of pole post 10-1-1 and tab 10-2-1, and ensure the connection strength of the three after welding.

[0081] In some embodiments, the emitting end 20-1-2 includes an outer frame 20-1-2-1 and a grid 20-1-2-2 disposed inside the outer frame 20-1-2-1. The grid 20-1-2-2 has a plurality of grid holes 20-1-2-2-1 for laser to pass through. The surface of the grid 20-1-2-2 away from the incident end 20-1-1 is flush with the surface of the emitting end 20-1-2 away from the incident end 20-1-1.

[0082] For grille 20-1-2-2, as Figure 4 , Figure 5 as well as Figure 9 As shown, the firing end 20-1-2 of the welding auxiliary tool 20-1 may include an outer frame 20-1-2-1 and a grid 20-1-2-2. The outer surface of the grid 20-1-2-2 is flush with the surface of the firing end 20-1-2, and it is provided with multiple grid holes 20-1-2-2-1 for the laser to pass through. That is, the grid 20-1-2-2 can form a grid-like compacted surface at the firing end 20-1-2. This compacted surface can both press the electrode tab 10-2-1 and the protective plate 10-3 tightly onto the surface of the electrode post 10-1-1, and allow the laser to pass through. After passing through the grid holes 20-1-2-2-1 within the grid 20-1-2-2, it can act on the surface of the protective sheet 10-3; the grid 20-1-2-2 can further compact the tabs 10-2-1, improve the compaction effect, reduce the interlayer gap, increase the absorption rate of laser energy by the material forming the pole post 10-1-1 and the tabs 10-2-1, and increase the welding strength; at the same time, multiple spaced dot weld marks 10-3-1 are formed within the protective sheet 10-3 for connecting the pole post 10-1-1 and the tabs 10-2-1.

[0083] In some embodiments, the welding auxiliary tool 20-1 is further provided with a protective gas release channel 20-2, and a laser channel 20-1-3 is formed between the incident end 20-1-1 and the exit end 20-1-2. The protective gas release channel 20-2 is connected to the laser channel 20-1-3. One of the two ports of the protective gas release channel 20-2 is opened at the incident end 20-1-1, and the other is opened on the inner sidewall of the laser channel 20-1-3.

[0084] For welding auxiliary tool 20-1, to prevent water and oxygen molecules in the air from affecting the welding quality of spot weld marks 10-3-1, such as... Figure 5 as well as Figures 7-10 As shown, in addition to the laser channel 20-1-3 connecting the incident end 20-1-1 and the exit end 20-1-2, the welding auxiliary tool 20-1 is also provided with a protective gas release channel 20-2 that releases protective gas toward the area where the dotted weld mark 10-3-1 is located.

[0085] Specifically, in the welding auxiliary tool 20-1, the laser channel 20-1-3 allows the laser to pass through so that the laser is emitted from the output end 20-1-2 and acts on the surface of the protective sheet 10-3 to form dotted weld marks 10-3-1 on the protective sheet 10-3. The shielding gas release channel 20-2 is connected to the laser channel 20-1-3; one end of it is located at the incident end 20-1-1, and the other end is located on the inner wall of the laser channel 20-1-3; when welding is performed using a laser, the shielding gas can enter the shielding gas release channel 20-2 through the port located at the incident end 20-1-1 via an external pipe, and then be released through the port located on the inner wall surface of the laser channel 20-1-3; since the outlet port of the shielding gas release channel 20-2 is close to the grid 20-1-2-2, the shielding gas can be directly released to the welding area of ​​the shielding plate 10-3. The shielding gas can be used to isolate and protect the molten pool before the formation of the spot weld 10-3-1, avoiding welding defects such as porosity or cracks in the spot weld 10-3-1, and ensuring the forming quality and welding effect of the spot weld 10-3-1.

[0086] For example, the shielding gas can be an inert gas such as nitrogen; specifically, since nitrogen is inert, it does not react with the spot weld marks 10-3-1 and the gas in the air at high temperatures, and the laser does not deflect or attenuate when passing through nitrogen, so it can be used in the laser welding process, which will not be elaborated here.

[0087] In some embodiments, the area of ​​the ejector end 20-1-2 is less than or equal to the area of ​​the protective sheet 10-3, and the ejector end 20-1-2 is located inside the protective sheet 10-3 when it abuts against the protective sheet 10-3 during the welding process.

[0088] For welding auxiliary tool 20-1, to ensure that the laser emitted from the output end 20-1-2 of welding auxiliary tool 20-1 can form evenly distributed and high-quality dot weld marks 10-3-1 on the surface of protective sheet 10-3, such as... Figure 8 As shown, the area of ​​the emission end 20-1-2 of the welding auxiliary tool 20-1 can be set to be less than or equal to the area of ​​the protective plate 10-3, and the emission end 20-1-2 of the welding auxiliary tool 20-1 can be located inside the protective plate 10-3 during the welding process, so that the laser emitted from the emission end 20-1-2 inside the welding auxiliary tool 20-1 can completely act on the protective plate 10-3, that is, the dotted weld marks 10-3-1 formed after welding are all inside the protective plate 10-3.

[0089] Furthermore, combined Figures 7-10 The welding process of pole post 10-1-1 and pole lug 10-2-1 is further described.

[0090] When assembling the single cell provided in this application, the cover plate assembly 10-1 and the electrode assembly 10-2 can be assembled first. Specifically, the tab 10-2-1 of the electrode assembly 10-2 is placed on the surface of the terminal post 10-1-1 on the inner surface of the cover plate assembly 10-1, and the protective sheet 10-3 is placed on the side of the tab 10-2-1 away from the terminal post 10-1-1. Then, the welding auxiliary tool 20-1 is placed on the surface of the protective sheet 10-3 to press the protective sheet 10-3 and the tab 10-2-1 onto the terminal post 10-1-1 using the welding auxiliary tool 20-1. Laser welding technology such as laser spot welding is then used to weld the terminal post 10-1-1 and the tab 10-2-1 together. Welding is performed on the protective sheet 10-1 and the protective sheet 10-3. With the help of the welding auxiliary tool 20-1, multiple spaced and discontinuous dot-shaped weld marks 10-3-1 can be formed in the protective sheet 10-3. The tab 10-2-1 is welded to the terminal post 10-1-1 through the multiple dot-shaped weld marks 10-3-1, and the protective sheet 10-3 is welded to the surface of the tab 10-2-1. Since the dot-shaped weld marks 10-3-1 are spaced on the surface of the protective sheet 10-3, it not only increases the connection area between the terminal post 10-1-1 and the tab 10-2-1 and ensures the connection strength between the two, but also reduces the actual welding area, so as to reduce the DCR in the single cell.

[0091] Furthermore, since the laser energy is relatively large and the heat is high during continuous welding, dividing the welding area into multiple dot-shaped weld marks 10-3-1 and distributing them at intervals can reduce the thermal impact of the dot-shaped weld marks 10-3-1 on the plastic part 10-1-2 inside the cover plate assembly 10-1, and prevent the plastic part 10-1-2 from melting due to excessive temperature.

[0092] Furthermore, since the electrode post 10-1-1 and the tab 10-2-1 of the electrode assembly 10-2 can be connected by laser welding technology, compared with the original welding process, this application can complete the welding of the protective sheet 10-3, the tab 10-2-1 and the electrode post 10-1-1 in one go, which not only ensures the welding strength, but also shortens the welding time.

[0093] Furthermore, the equipment used for laser welding is relatively simple, occupies little space, and has low investment and process costs.

[0094] Furthermore, the use of laser spot welding technology can avoid the formation of spatter, thereby reducing the generation of foreign matter and preventing the risk of abnormal K-value due to the presence of foreign matter, thus improving the overall performance and yield of individual cells.

[0095] It should be noted that the K-value refers to the voltage drop of a secondary battery per unit time, usually expressed in mV / d, and is used as an indicator to measure the self-discharge rate of a secondary battery. For example, the K-value of a secondary battery can be obtained by the following method: when the secondary battery has 60% charge, measure its voltage at 25±5℃ and record it as the first voltage. After standing for 48 hours, measure its voltage again and record it as the second voltage. The voltage drop per unit time at this time is recorded as K, i.e., K = (first voltage - second voltage) / standing time.

[0096] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of this application as described above, which are not provided in the details for the sake of brevity.

[0097] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A single-cell battery, characterized in that, include: A cover plate assembly, wherein the cover plate assembly is provided with pole posts; A housing, which is connected to the cover assembly to form a receiving cavity; An electrode assembly located within the receiving cavity; The protective sheet has multiple spaced dot-shaped weld marks formed by laser welding. The electrode post, the electrode tab of the electrode assembly, and the protective sheet are connected by the multiple dot-shaped weld marks. The protective sheet is located on the side of the electrode tab away from the electrode post.

2. The single-cell battery according to claim 1, characterized in that, Multiple dot-shaped solder marks are arranged in the protective sheet array, and the distance between two adjacent dot-shaped solder marks is greater than or equal to 1.5 mm.

3. The single-cell battery according to claim 2, characterized in that, The dotted solder marks are circular, and the diameter of the dotted solder marks is 1.5 mm to 3.5 mm; or, The dotted solder mark can be either square or rhomboid, and the diagonal length of the dotted solder mark is between 1.5mm and 3.5mm.

4. The single-cell battery according to claim 1, characterized in that, The plurality of the dotted solder marks form at least one welding area within the surface of the protective sheet, the shape of the welding area matching the shape of the side of the pole away from the cover plate assembly; The welding area can be one of the following: circular, semi-circular, elliptical, or polygonal.

5. The single-cell battery according to claim 1, characterized in that, Multiple dot-shaped solder marks form a welding area within the surface of the protective sheet, and the minimum distance between the edge of the welding area and the edge of the protective sheet is less than or equal to 2 mm.

6. The single-cell battery according to claim 1, characterized in that, The plurality of the dotted solder marks form a welding area within the surface of the protective sheet, and the ratio of the area of ​​the welding area to the area of ​​the electrode tab is 10% to 60%.

7. A welding auxiliary tool, characterized in that, Suitable for assisting in welding the single cell as described in any one of claims 1-6, wherein, The welding auxiliary tool is provided with a laser input end and a laser output end at opposite ends; The emission end is used to abut against the surface of the protective sheet away from the cover plate assembly during laser welding, so as to press the protective sheet and the electrode tab tightly against the surface of the electrode post through the emission end.

8. The welding auxiliary tool according to claim 7, characterized in that, The emission end includes an outer frame and a grid disposed inside the outer frame. The grid has multiple grid holes for the laser to pass through. The surface of the grille away from the incident end is flush with the surface of the exit end away from the incident end.

9. The welding auxiliary tool according to claim 8, characterized in that, The welding auxiliary tool is also equipped with a protective gas release channel, and a laser channel is formed between the incident end and the exit end. The protective gas release channel is connected to the laser channel; One of the two ports of the protective gas release channel is located at the incident end, and the other is located on the inner wall of the laser channel.

10. The welding auxiliary tool according to claim 7, characterized in that, The area of ​​the ejector end is less than or equal to the area of ​​the protective sheet, and the ejector end is located inside the protective sheet during the welding process.

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