Battery cell assembly primary structure, battery and processing method

Abstract

The embodiment of the present application provides a kind of battery and processing method of battery cell assembly primary structure.The battery cell assembly primary structure includes: battery cell body, the battery cell body has tab portion, the tab portion includes a plurality of sub-tab arranged in the thickness direction layer by layer, the tab portion includes the first face and the second face opposite in the thickness direction, the first face is used to be connected with cover plate;Exhaust assembly is at least provided to the first face, the exhaust assembly includes a plurality of first recesses arranged in the first face array, the first recess is used to provide gas escape path when the tab portion is welded with the cover plate.The battery cell assembly primary structure of the present application, when the tab portion is laser welded with the cover plate, part of the sub-tab that constitutes the inner wall of the first recess melts, forms gas escape path, reduces the influence on production rhythm.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a primary structure of a battery cell assembly, a battery, and a processing method thereof. Background Technology

[0002] In the manufacturing of new energy power batteries, the tabs, as the key structure for electrical connection between the internal electrode current collector and the external circuit (such as the battery cover or casing), directly determine the battery's conductivity, thermal management capability, and overall safety through their welding quality. With the continuous pursuit of high energy density and high-rate charge / discharge performance in electric vehicles and large-scale energy storage systems, the capacity and output power of single-cell power batteries are constantly increasing, and correspondingly, the current density carried by the tabs is significantly increasing.

[0003] To meet the demand for high current transmission, the number of layers of the electrode tabs has been increasing. This has led to a significant reduction in the efficiency of pores escaping during welding. In order to ensure production quality, it is necessary to reduce the production cycle and affect production efficiency. Summary of the Invention

[0004] This application provides a primary structure of a battery cell assembly, a battery, and a processing method. When the tab is laser-welded to the cover plate, part of the sub-tab forming the inner wall of the first groove melts, forming a gas escape path and reducing the impact on the production rhythm.

[0005] In a first aspect, embodiments of this application provide a primary structure for a battery cell assembly, comprising: a battery cell body having a tab portion, the tab portion including a plurality of sub-tabs stacked along the thickness direction, the tab portion including a first surface and a second surface opposite to each other along the thickness direction, the first surface being used to connect with a cover plate; and an exhaust assembly at least disposed on the first surface, the exhaust assembly including a plurality of first grooves arrayed on the first surface, the first grooves being used to provide a gas escape path when the tab portion is welded to the cover plate.

[0006] In some embodiments, along the thickness direction of the tab, the depth H1 of the first groove satisfies: 0.2mm≤H1≤0.3mm; and / or, along the first direction, the distance W1 between the bottom walls of two adjacent first grooves satisfies: 0.7mm≤W1≤0.8mm.

[0007] According to some embodiments of the present invention, the first groove has a first opening located on the first surface, and the distance W2 between two adjacent first openings satisfies: W2 = W1 - 2H1.

[0008] In some embodiments, the exhaust assembly further includes a plurality of first exhaust channels, the first exhaust channels being disposed within the tab portion and located between two adjacent first grooves, the first exhaust channels being along a first direction and penetrating the peripheral wall of the tab portion, the first direction being perpendicular to the thickness direction of the tab portion; and / or, the first exhaust channels being along a second direction and penetrating the peripheral wall of the tab portion, the first direction and the second direction being perpendicular to the thickness direction of the tab portion in pairs.

[0009] In some embodiments, the exhaust assembly further includes a second groove arrayed on the second surface.

[0010] According to some embodiments of the present invention, along the thickness direction of the tab portion, the depth H1 of the first groove and the depth H2 of the second groove satisfy the condition: H1 > H2.

[0011] According to some embodiments of the present invention, the second groove has a second opening located on the second surface, and along the first direction, the distance W1 between the bottom walls of two adjacent first grooves and the width W3 of the second opening satisfy the condition: W1 > W3.

[0012] According to some embodiments of the present invention, along the first direction, the length W4 of the bottom wall of the second groove satisfies: W4 = W3 - 2H2.

[0013] In some embodiments, along the thickness direction of the electrode portion, the number M of the sub-electrode layers satisfies: 100≤M≤130.

[0014] Secondly, embodiments of this application provide a battery, comprising: a housing defining a receiving cavity having an installation port communicating with the outside; the aforementioned primary structure of a battery cell assembly disposed within the receiving cavity; and a cover plate disposed at the installation port, wherein the cover plate and a first surface of the tab portion of the primary structure of the battery cell assembly are laser-welded to form a welded portion extending from the first surface to the second surface.

[0015] Thirdly, embodiments of this application provide a processing method for processing batteries as described above, the method comprising:

[0016] The electrode ear is held in place by a clamp;

[0017] Under preset processing conditions, an exhaust assembly is processed on the electrode tab by ultrasonic welding to form the primary structure of the battery cell assembly.

[0018] The battery cell assembly is encapsulated into a housing in a primary structure, and the cover plate is laser welded to the first surface.

[0019] In some embodiments, the processing conditions include: processing pressure P: 0.2MPa≤P≤0.4MPa; processing amplitude A: 15μm≤A≤40μm; processing frequency f: 15kHz≤f≤25kHz.

[0020] The primary structure, battery, and processing method of the battery cell assembly provided in this application embodiment involve setting an exhaust component on the tab portion. Before laser welding the battery cell assembly to the battery cover, the first surface of the tab portion has multiple arrayed first grooves pre-set. When the laser beam irradiates the contact area between the tab portion and the cover, the local metal rapidly melts to form a molten pool. At the same time, gases (such as interlayer air, adsorbed water vapor, oxide decomposition products, etc.) carried by the ultrasonic pre-welding or the material itself expand due to heat and escape upwards from the molten pool.

[0021] Since the electrode tab is formed by stacking multiple sub-tabs, during laser welding, the foil material of the sub-tabs melts, causing the first groove to break. This creates several discrete but interconnected microchannels between the first surface of the electrode tab and the cover plate. These microchannels shorten the diffusion path of gas from the deepest layer inside the electrode tab to the free surface of the molten pool. In other words, even with a large number of sub-tab layers (e.g., 120 layers), gas can quickly escape along the first groove, preventing it from being trapped and forming pores before the molten pool solidifies. This effectively alleviates the problem of gas stagnation caused by excessively long paths.

[0022] In this way, while ensuring sufficient venting, laser final welding can be completed at a higher welding speed, which not only ensures the density and conductivity of the weld but also improves the production cycle. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] Figure 1 This is a schematic diagram of the primary structure of the battery cell assembly provided in the embodiments of this application;

[0025] Figure 2 A partial cross-sectional view of the tab provided in an embodiment of this application;

[0026] Figure 3 A schematic diagram of the first surface of the tab provided in an embodiment of this application;

[0027] Figure 4 A schematic diagram of the second side of the tab provided in an embodiment of this application;

[0028] Figure 5 A disassembled diagram of the battery provided in an embodiment of this application;

[0029] Figure 6This is a flowchart illustrating the processing method according to an embodiment of this application.

[0030] Figure label:

[0031] 100-Cell assembly primary structure;

[0032] 110 - Cell body; 111 - Terminal tab; 1111 - First side; 1112 - Second side;

[0033] 120 - Exhaust assembly; 121 - First groove; 1211 - First opening; 122 - First exhaust passage; 123 - Second groove; 1231 - Second opening;

[0034] 200-battery;

[0035] 210 - Casing;

[0036] 220 - Cover plate; 221 - Welding part.

[0037] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0038] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0039] In the manufacturing of new energy power batteries, the tabs, as the key structure for electrical connection between the internal electrode current collector and the external circuit (such as the battery cover or casing), directly determine the battery's conductivity, thermal management capability, and overall safety through their welding quality. With the continuous pursuit of high energy density and high-rate charge / discharge performance in electric vehicles and large-scale energy storage systems, the capacity and output power of single-cell power batteries are constantly increasing, and correspondingly, the current density carried by the tabs is significantly increasing.

[0040] To meet the demands of high-current transmission, the number of electrode layers is increasingly increasing. Currently, the industry commonly employs a composite welding process combining ultrasonic welding and laser welding to achieve a reliable connection between multi-layer electrode layers and the battery cover. This process typically includes three main steps: First, ultrasonic welding is used to create several pre-weld points between the multi-layer electrode layers and the casing or transition structure to provide initial mechanical positioning and fixation; second, low-power laser welding is used for pre-welding, forming a preliminary metallurgical bond between the pre-welded area and the cover; finally, high-power laser welding is used for final welding, completing a high-strength, low-resistance final connection. The advantage of this composite process is that it eliminates the need for intermediate components such as metal protective sheets used for buffering or protection in traditional structures, thereby achieving lightweight battery structure and simplified assembly process.

[0041] However, during ultrasonic pre-welding, due to the presence of tiny gaps, oxide films, or adsorbed gases between the metal foil layers, a large amount of gas will be released into the high-temperature molten pool formed by subsequent laser welding. These gases must escape fully before the molten pool solidifies; otherwise, porosity defects will form.

[0042] The inventors' research shows that when the number of tab layers increases from 60 to 120, the path length for gas to escape from the innermost layer to the surface of the molten pool almost doubles, resulting in an escape time that is approximately 2.3 times longer. Under conventional laser welding parameters, the liquid lifespan of the molten pool is insufficient to support complete gas expulsion, leading to a porosity residual rate of 8%–12% in the weld, which severely weakens the density and conductivity of the weld joint.

[0043] Therefore, to alleviate the porosity problem, existing processes have had to significantly reduce laser welding speed (typically to 260–280 mm / s, only 40%–60% of conventional welding speed) to prolong the molten pool duration and promote gas escape. While this adjustment improves welding quality to some extent, it significantly extends the welding cycle time for a single electrode, becoming a key bottleneck restricting the capacity improvement of high-speed automated production lines.

[0044] Furthermore, the residual gas inside the molten pool expands rapidly under the high temperature and pressure of laser welding, which can easily trigger local turbulence or even explosions, resulting in a 2-4 fold increase in the amount of metal spatter. This spatter not only affects the uniformity of the weld appearance but may also adhere to other components inside the battery, posing a short circuit risk. More seriously, gas disturbances may induce internal defects such as microcracks and shrinkage cavities, creating potential safety hazards during long-term use.

[0045] In view of this, this application provides a primary structure of a battery cell assembly, a battery, and a processing method. When the tab is laser welded to the cover plate, part of the sub-tab forming the inner wall of the first groove melts, forming a gas escape path and reducing the impact on the production rhythm.

[0046] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0047] refer to Figures 1 to 5 In a first aspect, embodiments of this application provide a primary structure 100 for a battery cell assembly, which includes a battery cell body 110 and an exhaust assembly 120.

[0048] The cell body 110 is the core energy storage unit of the battery 200, providing a site for electrochemical reactions, and achieving electrical connection between the internal electrodes and the external circuit through the tabs 111 on the cell body 110.

[0049] The tab portion 111 includes a plurality of sub-tabs arranged in layers along the thickness direction, and the thickness of the tab portion 111 increases with the number of layers of sub-tabs.

[0050] The tab portion 111 includes a first surface 1111 and a second surface 1112. The first surface 1111 and the second surface 1112 are opposite each other along the thickness direction of the tab portion 111. The first surface 1111 is the welding interface facing the cover plate 220 and directly participates in the metallurgical bonding process with the cover plate 220. The second surface 1112 is opposite to the cover plate 220.

[0051] The exhaust assembly 120 is used to actively guide and accelerate the escape of internal gas during laser welding to avoid the formation of porosity defects. The exhaust assembly 120 is provided at least on the first surface 1111, that is, the exhaust assembly 120 can be provided on the first surface 1111, or the exhaust assembly 120 can be provided on both the first surface 1111 and the second surface 1112, or the exhaust assembly 120 can also be provided on the first surface 1111, the second surface 1112 and inside the tab portion 111.

[0052] The exhaust assembly 120 includes a plurality of first grooves 121 arranged in an array on the first surface 1111. The first grooves 121 are used to provide a gas escape path when the electrode tab 111 is welded to the cover plate 220. That is, the first grooves 121 form a partially open channel between the electrode tab 111 and the cover plate 220, shortening the escape path of gas from the inside of the electrode tab 111 to the surface of the molten pool and improving the exhaust efficiency.

[0053] The primary structure 100 of the battery cell assembly of this application includes an exhaust assembly 120 on the tab 111. Before laser welding of the battery cell assembly to the cover plate 220 of the battery 200, the first surface 1111 of the tab 111 has multiple arrayed first grooves 121 pre-set. When the laser beam irradiates the contact area between the tab 111 and the cover plate 220, the local metal melts rapidly to form a molten pool. At the same time, gases (such as interlayer air, adsorbed water vapor, oxide decomposition products, etc.) carried by the ultrasonic pre-welding or the material itself expand due to heat and escape upwards from the molten pool.

[0054] Since the tab portion 111 is formed by stacking multiple sub-tabs, during laser welding, the foil material of the sub-tabs melts, causing the first groove 121 to break. This creates several discrete but interconnected microchannels between the first surface 1111 of the tab portion 111 and the cover plate 220. These channels significantly shorten the diffusion path of gas from the deepest layer inside the tab portion 111 to the free surface of the molten pool. In other words, even when the number of sub-tab layers in the tab portion 111 is large (e.g., 120 layers), the gas can be quickly discharged along the first groove 121, preventing it from being trapped and forming pores before the molten pool solidifies. This effectively alleviates the gas retention problem caused by excessively long paths.

[0055] In this way, while ensuring sufficient venting, laser final welding can be completed at a higher welding speed, which not only ensures the density and conductivity of the weld but also improves the production cycle.

[0056] Furthermore, since multiple first grooves 121 are arranged in an array on the first surface 1111, the exhaust path is evenly distributed throughout the welding area, which helps to maintain the overall stability of the molten pool during welding, thereby reducing turbulence and spatter and ensuring welding quality.

[0057] In this embodiment, the first groove 121 on the tab 111 can be formed by ultrasonic processing. The ultrasonic instrument processes the first groove 121 under preset pressure, amplitude and frequency conditions. The specific structure of the first groove 121 is determined by the shape of the ultrasonic welding head. For example, the ultrasonic welding head can be a ball head, a conical head or other structures.

[0058] refer to Figure 2 and Figure 3 In some embodiments, along the thickness direction of the tab 111, the depth H1 of the first groove 121 satisfies: 0.2mm≤H1≤0.3mm. For example, the depth H1 of the first groove 121 can be 0.2mm, 0.25mm or 0.3mm. Of course, the depth H1 of the first groove 121 can also be other values, which are not limited in this application.

[0059] On the one hand, the depth of the first groove 121 should not be too large (e.g., exceeding 0.3 mm), which would excessively weaken the effective load-bearing cross-section of the contact area between the tab 111 and the cover plate 220. This would prevent a sudden drop in the mechanical strength of the tab 111 or an aggravation of the current concentration effect after welding due to the excessive depth of the first groove 121, thus affecting the service life of the battery 200. On the other hand, the depth of the first groove 121 should not be too small (e.g., less than 0.2 mm). Insufficient depth of the first groove 121 would prevent the formation of an effective airflow channel during laser welding, affecting the gas discharge efficiency.

[0060] For ease of description and understanding, in this application, the direction extending away from the battery cell body 110 along the tab 111 can be a second direction, and the width direction of the tab 111 can be a first direction.

[0061] refer to Figure 2 In some embodiments, along the first direction, the distance W1 between the bottom walls of two adjacent first grooves 121 satisfies: 0.7mm≤W1≤0.8mm. For example, the distance W1 between the bottom walls of two adjacent first grooves 121 can be 0.7mm, 0.75mm or 0.8mm. Of course, the distance W1 between the bottom walls of two adjacent first grooves 121 can also be other values, which are not limited in this application.

[0062] On the one hand, it avoids the distance W1 between the bottom walls of two adjacent first grooves 121 being too small, resulting in an excessively high density of the first grooves 121. This would significantly reduce the effective connection area of ​​the first surface 1111 of the electrode tab 111, affecting the uniformity of heat conduction during laser welding and potentially causing local overmelting or collapse. On the other hand, it avoids the distance W1 between the bottom walls of two adjacent first grooves 121 being too large, resulting in a sparse distribution of microchannels formed by the first grooves 121 during welding. Under high-speed welding conditions, this would not be able to cover the entire molten pool area, leaving some areas at risk of gas retention. A distance W1 between the bottom walls of two adjacent first grooves 121 of 0.7mm-0.8mm ensures that the arrayed first grooves 121 form a continuous and efficient "micro-venting network" across the entire welding interface, while also allowing the electrode tab 111 to retain sufficient solid metal area for a strong metallurgical bond with the cover plate 220, thus balancing porosity suppression and connection strength.

[0063] Understandably, in this embodiment, the distance W1 between the bottom walls of two adjacent first grooves 121 can be the distance between the adjacent ends of two adjacent first grooves 121 along the first direction.

[0064] According to some embodiments of the present invention, the first groove 121 has a first opening 1211 located on the first surface 1111, and the distance W2 between two adjacent first openings 1211 satisfies: W2=W1-2H1.

[0065] In this embodiment, the first groove 121 can be a tapered structure that gradually tapers along the depth direction. The sidewall of the first groove 121 can have a certain inclination angle. By setting W2=W1-2H1, a compensation mechanism for the lateral expansion effect of the first groove 121 is provided: that is, given the known bottom wall distance W1 of two adjacent first grooves 121 and the depth H1 of the first groove 121, the actual net distance W2 at the opening of two adjacent first grooves 121 can be deduced, thereby ensuring that the gas escape channel distribution density on the outermost surface (i.e., the welding interface) of the electrode tab 111 matches the internal structure.

[0066] refer to Figure 2 In some embodiments, the exhaust assembly 120 further includes a plurality of first exhaust channels 122, which are disposed within the tab portion 111 and are located between two adjacent first grooves 121. Understandably, when the first grooves 121 are formed by ultrasonic processing, the first exhaust channels 122 are formed between the two first grooves 121 by adjusting the processing parameters.

[0067] The first exhaust channel 122 runs along a first direction and penetrates the peripheral wall of the tab 111, and the first direction is perpendicular to the thickness direction of the tab 111. The exhaust path relying solely on the first groove 121 mainly escapes to the surface of the molten pool along the thickness direction. However, in the tab 111 with multiple layers (such as 120 layers), the internal gas still needs to pass through a large number of metal foil layers of the sub-tabs to reach the outside of the tab 111, resulting in a long path and high resistance.

[0068] By setting the first exhaust channel 122 to penetrate the peripheral wall of the electrode lug 111 in the first direction, the gas can diffuse laterally in the horizontal plane and be directly discharged from the side of the electrode lug to the external environment or welding protective atmosphere.

[0069] Furthermore, the first exhaust channel 122 extends along the second direction and penetrates the peripheral wall of the tab 111, with the first direction and the second direction being perpendicular to the thickness direction of the tab 111. In other words, the first exhaust channel 122, extending along the first direction and the second direction respectively, forms an exhaust network inside the tab 111. During laser welding, it forms a composite exhaust mechanism with the microchannels formed by the first groove 121, shortening the average escape distance of the innermost gas in the tab 111 and improving exhaust efficiency.

[0070] Understandably, under the instantaneous high temperature of laser welding, the gas inside the multi-layered sub-tabs expands rapidly. If only the first groove 121 is used for venting, a high-pressure gas pocket is easily formed in the middle of the tab 111, leading to an explosive release at the bottom of the molten pool and causing violent spatter. However, the first venting channel 122, which runs laterally through the tab 111, provides a low-pressure venting path, allowing the gas to be released evenly in the circumferential direction. This effectively balances the gas pressure distribution below the molten pool, which helps reduce turbulence intensity and the probability of metal spatter, and improves weld formation quality and process stability.

[0071] refer to Figure 2 and Figure 4 In some embodiments, the exhaust assembly 120 further includes a second groove 123 arrayed on the second surface 1112.

[0072] During laser welding, the tab 111 needs to be subjected to uniform pressure from both the top and bottom sides by the clamp to ensure interlayer adhesion and a flat welding interface. If the second surface 1112 is a complete plane, under high pressure clamping, slight thickness deviations or surface unevenness of the multilayer foil can easily lead to local suspension or stress concentration, which can cause welding misalignment or incomplete welding. The arrayed second grooves 123 can form a micro-buffer zone and stress dispersion point between the clamping head and the tab 111, making the clamping force more evenly distributed throughout the tab 111 area, effectively avoiding welding misalignment caused by local warping or slippage, and significantly improving clamping repeatability accuracy.

[0073] Furthermore, the tab portion 111 of the high-level digital electrode is prone to expansion along the thickness direction and contraction and springback after cooling under laser heat input. If the second surface 1112 is a continuous solid structure with strong rigid constraints, it will aggravate the accumulation of internal residual stress, causing the electrode to warp as a whole after welding, affecting subsequent assembly (such as the fit with the cover plate 220). The second groove 123 forms a controllable flexible area on the second surface 1112, allowing the tab portion 111 to undergo slight deformation during thermal cycling without generating excessive internal stress, thereby reducing the amount of deformation after welding and ensuring that the tab portion 111 maintains good flatness after welding.

[0074] According to some embodiments of the present invention, along the thickness direction of the tab 111, the depth H1 of the first groove 121 and the depth H2 of the second groove 123 satisfy the condition: H1 > H2.

[0075] By making the depth H1 of the first groove 121 greater than the depth H2 of the second groove 123, on the one hand, while ensuring that the first groove 121 has sufficient venting function, the depth of the second groove 123 is avoided from being too large, which would reduce the structural strength of the tab 111 and affect the service life of the battery 200. On the other hand, during the laser welding process, energy is mainly input from the first surface 1111, and the heat-affected zone extends along the thickness direction towards the second surface 1112. If the second groove 123 is too deep, its bottom may approach or enter the heat-affected core area, causing local molten metal to flow into the second groove 123, forming uncontrollable burrs or weld beads, which would affect the post-weld flatness.

[0076] According to some embodiments of the present invention, the second groove 123 has a second opening 1231 located on the second surface 1112, and along the first direction, the distance W1 between the bottom walls of two adjacent first grooves 121 and the width W3 of the second opening 1231 satisfy the condition: W1 > W3.

[0077] During laser welding, the first groove 121, which serves as the primary venting area, is a crucial load-bearing region for maintaining the overall mechanical strength and conductive continuity of the tab 111. If the width of the second opening 1231 is too large, the projection of the second groove 123 in the thickness direction may completely cover or even exceed the solid area between the bottom walls of adjacent first grooves 121, resulting in slotting on both the upper and lower surfaces of this area, forming a "through-type weak zone." Under the combined effects of the high temperature and fixture pressure of laser welding, such areas are prone to local collapse, tearing, or excessive plastic deformation, thereby affecting the weld formation quality. By ensuring that the distance W1 between the bottom walls of two adjacent first grooves 121 is greater than the width W3 of the second opening 1231, it can be ensured that the opening of the second groove 123 is always recessed within the solid area defined by the distance between the bottom walls of the first grooves 121, preserving sufficient through-metal bridging and maintaining structural integrity.

[0078] According to some embodiments of the present invention, along the first direction, the length W4 of the bottom wall of the second groove 123 satisfies: W4 = W3 - 2H2.

[0079] During the manufacturing process of the tab 111, the second groove 123 can be formed by stamping, laser etching, or molding. Regardless of the process used, the sidewall of the second groove 123 often has a certain slope (not ideally vertical), resulting in the bottom wall dimension of the second groove 123 being smaller than the dimension of the second opening 1231. W4=W3−2H2 implicitly assumes that the sidewall is straight and the angle is fixed (for example, if H2=0.1mm, W3=0.5mm, then W4=0.3mm, corresponding to a horizontal offset of 0.1mm on one side, i.e., a 45° sidewall). This formula directly links the design parameters with the actual processing results, providing a clear basis for mold or laser path design, avoiding the bottom wall being too narrow or even closed due to ignoring the influence of depth on the bottom width, thereby ensuring the stable reproduction of the second groove 123 structure in mass production.

[0080] In some embodiments, along the thickness direction of the tab portion 111, the number of sub-tab layers M satisfies: 100 ≤ M ≤ 130. For example, the number of sub-tab layers M can be 100, 110, 120, or 130. Of course, the number of sub-tab layers M can also be other values, which are not limited in this application.

[0081] In the existing technology, when the number of sub-electrode layers is less than 80, the gas escape path is relatively short, and conventional welding processes can still meet the quality requirements; however, once the number of sub-electrode layers exceeds 130, even if the exhaust structure of this solution is adopted, the total thickness may be too large (more than 1.5mm), resulting in severe laser energy attenuation and insufficient penetration depth, making it difficult to guarantee welding reliability.

[0082] In existing electric vehicles and energy storage systems, the number of positive / negative electrode layers in blade batteries 200 or large cylindrical batteries 200 is generally between 100 and 130 layers to meet the requirements of fast charging above 3C and continuous high-rate discharge. Limiting M to this range makes the implementation of this highly feasible technical solution even more feasible.

[0083] refer to Figure 5 Secondly, embodiments of this application provide a battery 200, which includes a housing 210, the aforementioned primary structure 100 of the battery cell assembly, and a cover plate 220.

[0084] The housing 210 constitutes the external encapsulation structure of the battery 200. The cavity formed inside it is used to fix and protect the cell assembly and prevent external mechanical impact, moisture or contaminants from entering. The cavity has an installation port that communicates with the outside. The housing 210 provides a reference for the assembly of the cover plate 220 by defining the position and size of the installation port, and ensures the alignment accuracy between the tab 111 and the cover plate 220.

[0085] The primary structure 100 of the battery cell assembly is located within the receiving cavity, and the cover plate 220 is located at the mounting port. The cover plate 220 serves as both a sealing cap for the battery 200 and an electrical input terminal for the external circuit. The cover plate 220 is directly connected to the tab 111 and performs multiple functions, including current lead-out and safety pressure relief (if an explosion-proof valve is integrated).

[0086] The cover plate 220 and the first surface 1111 of the tab portion 111 of the primary structure 100 of the battery cell assembly are laser welded together to form a welded portion 221, which extends from the first surface 1111 to the second surface 1112.

[0087] Laser welding utilizes a high-energy-density laser beam to instantly melt metal, forming a molten pool with a large depth-to-width ratio. In this design, the welded portion 221 extends from the first surface 1111 to the second surface 1112, indicating that the laser energy fully penetrates the entire tab portion 111, achieving full-section metallurgical bonding. This process is highly coordinated with the venting design of the first groove 121: the first groove 121 guides gas to escape rapidly before the molten pool solidifies, preventing pore encapsulation; while the penetrating weld depth ensures reliable connection between all layers, eliminating the risk of "surface penetration, internal incomplete connection".

[0088] Furthermore, since the welded part 221 forms a through-welded structure, while improving the exhaust efficiency, the tensile strength of the welded part 221 between the cover plate 220 and the tab part 111 can exceed 200MPa, thereby improving the structural stability of the battery 200 during long-term use.

[0089] refer to Figure 6 Thirdly, embodiments of this application provide a processing method for processing the battery 200 as described above, the method comprising the following steps:

[0090] S1: Clamp the tab 111 using a clamp;

[0091] S2: Under preset processing conditions, an exhaust assembly 120 is processed on the tab 111 by ultrasonic welding to form a primary structure 100 of the battery cell assembly.

[0092] S3: The primary structure 100 of the battery cell assembly is encapsulated in the housing 210, and the cover plate 220 is laser welded to the first surface 1111.

[0093] In step S1, a contour jig is used to clamp and fix the tabs 111 of the battery cell body 110 that has been stacked or wound. The jig includes an upper pressure head and a lower support platform. Both apply uniform pressure along the thickness direction of the tabs 111 to make the multi-layer tabs fit tightly together and eliminate interlayer gaps and warping.

[0094] In step S2, a forming mold with a preset array of micro-convex molds is used to locally plastically deform the clamped tab 111 under the assistance of ultrasonic vibration, thereby forming a first groove 121 on the first surface 1111 and a second groove 123 on the second surface 1112.

[0095] In step S3, the formed primary structure 100 of the battery cell assembly is placed into the receiving cavity of the housing 210, ensuring that the tab 111 faces the mounting opening and is centered. A cover plate 220 (typically made of aluminum or copper alloy) is placed over the mounting opening of the housing 210, ensuring its lower surface is in close contact with the first surface 1111 of the tab 111. A high-power fiber laser (wavelength 1070nm, power 800–1500W) is used in an inert gas (such as Ar or...) Under the protection of the cover plate 220, the first surface 1111 of the electrode ear 111 is welded along the preset trajectory.

[0096] During the welding process, the first groove 121 serves as a gas escape channel, allowing the gas released between layers to exit along a short path. Simultaneously, the laser energy fully penetrates the tab 111, forming a continuous welded section 221 extending from the first surface 1111 to the second surface 1112, achieving full-thickness metallurgical bonding. After welding, the finished battery 200 is obtained through airtightness testing and electrical performance testing.

[0097] Thus, by processing the exhaust structure before the final laser welding, laser welding can be completed under high-speed and high-quality conditions, taking into account efficiency, strength and safety, and fully meeting the mass production requirements of the high-power power battery 200.

[0098] In some embodiments, in step S2, high-frequency mechanical vibration is used to reduce the local yield strength of the metal foil (i.e., the sub-tab) to achieve fine plastic deformation under low load, forming the first groove 121 and the second groove 123.

[0099] The processing conditions include: processing pressure P: 0.2MPa ≤ P ≤ 0.4MPa. For example, the processing pressure P can be 0.2MPa, 0.3MPa, or 0.4MPa. Of course, the processing pressure P can also be other values, and this application does not limit it.

[0100] On the one hand, it avoids the processing pressure being too low, which is insufficient to drive the mold protrusion to penetrate the multi-layer sub-tabs, resulting in insufficient depth of the first groove 121 and failure to form an effective exhaust channel; on the other hand, it avoids the processing pressure being too high, which would cause the bottom foil of the tab portion 111 to be excessively stretched, torn, or have interlayer misalignment.

[0101] Processing amplitude A: 15μm≤A≤40μm. For example, the processing amplitude A can be 15μm, 30μm, or 40μm. Of course, the processing amplitude A can also be other values, and this application does not limit it.

[0102] A≥15μm can effectively stimulate the movement of dislocations inside the metal foil of the tab 111, thereby reducing flow stress and allowing the first groove 121 to be formed completely. A≤40μm avoids energy scattering, local overheating or mold jumping caused by excessive amplitude, and prevents the edges of adjacent first grooves 121 from merging or dimensional distortion.

[0103] Processing frequency f: 15kHz ≤ f ≤ 25kHz. For example, the processing frequency f can be 15kHz, 20kHz, or 25kHz. Of course, the processing frequency f can also be other values, and this application does not limit this.

[0104] Among them, f≥15kHz can ensure a sufficient number of friction cycles per unit time, and f≤25kHz avoids entering the high-frequency attenuation region, thereby ensuring the forming quality of the first groove 121.

[0105] The following are some specific examples to illustrate this:

[0106] Example 1

[0107] The first groove is ultrasonically machined into the tab, with H1 being 0.2 mm and W1 being 0.7 mm. The cover plate is then laser-welded to the tab.

[0108] Example 2

[0109] The first groove is ultrasonically machined into the electrode tab, with H1 being 0.25mm and W1 being 0.75mm. The cover plate is then laser-welded to the electrode tab.

[0110] Example 3

[0111] The first groove is ultrasonically machined into the electrode tab, with H1 being 0.3mm and W1 being 0.8mm. The cover plate is then laser-welded to the electrode tab.

[0112] Comparative Example 1

[0113] The electrode tabs are made with electrical discharge etching to create ultrasonic pre-welding points, and the electrode tabs are laser-welded to the cover plate.

[0114] Comparative Example 2

[0115] The first groove is ultrasonically machined into the electrode tab, with H1 being 0.15mm and W1 being 0.6mm. The cover plate is then laser-welded to the electrode tab.

[0116] Comparative Example 3

[0117] The electrode tabs are made with an electrical discharge etching pattern and a mesh pattern design to create ultrasonic pre-welding points, and the cover plate is laser-welded to the electrode tabs.

[0118] The following table shows the test results.

[0119]

[0120] In conjunction with Examples 1-3, Comparative Examples 1 and 3, a first groove was ultrasonically machined on the electrode tab. The first groove plays a guiding role in the subsequent laser welding process, shortening the diffusion path of gas from the deepest part inside the electrode tab to the free surface of the molten pool. The gas can be quickly discharged along the first groove, avoiding being trapped and forming pores before the molten pool solidifies. This effectively alleviates the problem of gas retention caused by excessively long paths, resulting in a good appearance quality of the welded part.

[0121] In conjunction with Examples 1-3 and Comparative Example 2, there is a certain relationship between the size of the first groove and its flow guiding capacity. When the size of the first groove is outside the preferred range, the flow guiding capacity is poor, the melting depth of the formed molten pool is insufficient, and the connection stability between the electrode tab and the cover plate is affected.

[0122] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A primary structure (100) for a battery cell assembly, characterized in that, include: The battery cell body (110) has a tab portion (111), the tab portion (111) includes a plurality of sub-tabs stacked along the thickness direction, the tab portion (111) includes a first surface (1111) and a second surface (1112) opposite to each other along the thickness direction, the first surface (1111) is used to connect with the cover plate (220); An exhaust assembly (120) is provided at least on the first surface (1111). The exhaust assembly (120) includes a plurality of first grooves (121) arranged in an array on the first surface (1111). The first grooves (121) are used to provide a gas escape path when the tab (111) is welded to the cover plate (220).

2. The primary structure (100) of the battery cell assembly according to claim 1, characterized in that, Along the thickness direction of the tab (111), the depth H1 of the first groove (121) satisfies: 0.2mm ≤ H1 ≤ 0.3mm; and / or, Along the first direction, the distance W1 between the bottom walls of two adjacent first grooves (121) satisfies: 0.7mm≤W1≤0.8mm.

3. The primary structure (100) of the battery cell assembly according to claim 2, characterized in that, The first groove (121) has a first opening (1211) located on the first surface (1111), and the distance W2 between two adjacent first openings (1211) satisfies: W2=W1-2H1.

4. The primary structure (100) of the battery cell assembly according to claim 1, characterized in that, The exhaust assembly (120) further includes a plurality of first exhaust channels (122), each first exhaust channel (122) being disposed within the tab (111) and located between two adjacent first grooves (121). The first exhaust channel (122) extends along a first direction and penetrates the peripheral wall of the tab (111), the first direction being perpendicular to the thickness direction of the tab (111); and / or, The first exhaust channel (122) runs along the second direction and penetrates the peripheral wall of the tab (111), and the first direction and the second direction are perpendicular to the thickness direction of the tab (111).

5. The primary structure (100) of the battery cell assembly according to claim 1, characterized in that, The exhaust assembly (120) further includes a second groove (123) arrayed on the second surface (1112).

6. The primary structure (100) of the battery cell assembly according to claim 5, characterized in that, Along the thickness direction of the tab (111), the depth H1 of the first groove (121) and the depth H2 of the second groove (123) satisfy the condition: H1 > H2.

7. The primary structure (100) of the battery cell assembly according to claim 6, characterized in that, The second groove (123) has a second opening (1231) located on the second surface (1112). Along the first direction, the distance W1 between the bottom walls of two adjacent first grooves (121) and the width W3 of the second opening (1231) satisfy the condition: W1 > W3.

8. The primary structure (100) of the battery cell assembly according to claim 7, characterized in that, Along the first direction, the length W4 of the bottom wall of the second groove (123) satisfies: W4 = W3 - 2H2.

9. The primary structure (100) of the battery cell assembly according to claim 1, characterized in that, Along the thickness direction of the tab portion (111), the number of layers M of the sub-tabs satisfies: 100≤M≤130.

10. A battery (200), characterized in that, include: A housing (210) defines a receiving cavity having an installation port communicating with the outside; The primary structure (100) of the battery cell assembly according to any one of claims 1-9, wherein the primary structure (100) of the battery cell assembly is disposed within the receiving cavity; A cover plate (220) is provided at the mounting port. The cover plate (220) and the first surface (1111) of the tab portion (111) of the primary structure (100) of the battery cell assembly are laser welded to form a welded part (221). The welded part (221) extends from the first surface (1111) to the second surface (1112).

11. A processing method, characterized in that, The method for processing the battery (200) as described in claim 10 includes: The tab (111) is held by a clamp. Under preset processing conditions, an exhaust assembly (120) is processed on the electrode tab (111) by ultrasonic welding to form a primary structure (100) of the battery cell assembly. The primary structure (100) of the battery cell assembly is encapsulated in the housing (210), and the cover plate (220) is laser welded to the first surface (1111).

12. The processing method according to claim 11, characterized in that, The processing conditions include: processing pressure P: 0.2MPa ≤ P ≤ 0.4MPa; Processing amplitude A: 15μm≤A≤40μm; Processing frequency f: 15kHz≤f≤25kHz.

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