Top sealing process of soft package battery

Abstract

This invention relates to the field of lithium-ion battery applications and discloses a top-sealing process for a pouch battery. The process includes: placing the top sealing edge of the pouch battery to be packaged between an upper sealing head and a lower sealing head of a top-sealing device; driving the upper sealing head to close with the lower sealing head; hot-pressing the positive tab region of the pouch battery using a first set of packaging parameters; simultaneously hot-pressing the negative tab region of the pouch battery using a second set of packaging parameters; and hot-pressing other regions besides the positive and negative tab regions using a third set of packaging parameters. The first set of packaging parameters includes a first packaging temperature and a first packaging time, and the second set of packaging parameters includes a second packaging temperature and a second packaging time. The first packaging temperature is higher than the second packaging temperature, and the first packaging time is shorter than the second packaging time.

Description

Technical Field

[0001] This invention relates to the field of pouch cell manufacturing, and more particularly to a top sealing process for pouch cells. Background Technology

[0002] The soft-pack battery uses an aluminum-plastic composite film as the outer shell material, and the battery cell is sealed inside the packaging through a heat-sealing process. Top sealing is one of the key processes in the packaging of soft-pack batteries. It requires sealing the positive and negative tabs and the two layers of aluminum-plastic film together by heat pressing. While ensuring the insulation and isolation of the positive and negative tabs, it achieves reliable adhesion and sealing between the polypropylene layer of the aluminum-plastic film and the tabs, as well as between the polypropylene layer of the aluminum-plastic film itself.

[0003] In existing top sealing processes, the same heat sealing parameters are usually used to encapsulate the positive tab area, the negative tab area, and the inter-tab sealing area between them. That is, the entire top sealing edge area is heat-pressed and sealed with a uniform encapsulation temperature and time during mold closing. Summary of the Invention

[0004] One of the objectives of this invention is to provide a top sealing process for a pouch battery to improve the reliability of the top sealing.

[0005] This invention provides a top sealing process for a pouch battery, comprising: Place the top sealing edge of the soft-pack battery to be packaged between the upper and lower sealing heads of the top sealing equipment; The upper end cap is driven to close with the lower end cap, and the positive tab area of ​​the soft pack battery is heat-sealed with the first packaging parameter group, the negative tab area of ​​the soft pack battery is heat-sealed with the second packaging parameter group, and the other areas except the positive tab area and the negative tab area are heat-sealed with the third packaging parameter group. The first packaging parameter set includes a first packaging temperature and a first packaging time, and the second packaging parameter set includes a second packaging temperature and a second packaging time; the first packaging temperature is higher than the second packaging temperature, and the first packaging time is shorter than the second packaging time.

[0006] Optionally, the first encapsulation temperature is 190°C to 210°C, and the first encapsulation time is 1.5s to 2.5s.

[0007] Optionally, the second encapsulation temperature is 150°C to 170°C, and the second encapsulation time is 3.0s to 4.5s.

[0008] Optionally, the third encapsulation temperature is 160°C to 190°C, and the third encapsulation time is 2.0s to 3.5s.

[0009] Optionally, the heat sealing pressure for the positive electrode tab region is greater than the heat sealing pressure for the negative electrode tab region.

[0010] Optionally, the heat sealing pressure for the positive electrode tab region is 0.4 MPa to 0.6 MPa, and the heat sealing pressure for the negative electrode tab region is 0.3 MPa to 0.45 MPa.

[0011] Optionally, before the hot-press sealing, the surface of the positive electrode tab that contacts the aluminum-plastic film polypropylene layer is roughened to form a micron-level uneven structure.

[0012] Optionally, a second ceramic heat insulation layer is further provided below the tab groove of the upper end cap and / or the lower end cap corresponding to the negative electrode tab area.

[0013] Optionally, when the top sealing edge is hot-pressed and sealed, a lateral pre-sealing section is also formed at each intersection of the top sealing edge and the two side sealing edges along the side sealing direction, and the two lateral pre-sealing sections extend from both ends of the top sealing edge along the side sealing direction.

[0014] Optionally, before the hot-press sealing, a plurality of parallel recesses are stamped on an integral aluminum-plastic film, and each battery cell is correspondingly installed in each of the recesses. The positive and negative tabs of each battery cell extend outward from the top of each recess, and the bottom end of the aluminum-plastic film is folded over to cover each recess. The upper end cap and the lower end cap are respectively provided with a plurality of pairs of tab grooves along the length direction. The tab grooves on the upper end cap and the lower end cap are respectively facing each other, and each pair of tab grooves corresponds to the two tabs of one battery cell. During mold closing, each of the positive and negative tab regions of each of the battery cells is located in the tab groove. The positive tab regions are heat-sealed using the first packaging parameter set, while the negative tab regions are heat-sealed using the second packaging parameter set. The other regions, excluding the positive and negative tab regions, are heat-sealed using the third packaging parameter set. A continuous heat-sealed area is formed on the top of the overall aluminum-plastic film during the mold closing process.

[0015] Optionally, on the upper and lower end caps, partition grooves are respectively provided on both sides of each tab groove, and a first ceramic heat insulation layer is embedded and fixed in each partition groove to thermally isolate each tab groove from the adjacent non-tab area.

[0016] Compared with the existing technology that uses a uniform packaging temperature and packaging time to thermo-seal the entire top edge, the application of this technology has the following advantages: In the same top sealing molding process, the positive electrode tab area is thermo-sealed using a first set of packaging parameters, the negative electrode tab area is thermo-sealed using a second set of packaging parameters, and the non-tab area is thermo-sealed using a third set of packaging parameters. The first set of packaging parameters includes a first packaging temperature and a first packaging time, and the second set of packaging parameters includes a second packaging temperature and a second packaging time. The first packaging temperature is higher than the second packaging temperature, and the first packaging time is shorter than the second packaging time.

[0017] The positive electrode tab is typically made of aluminum, with a dense oxide layer on its surface that hinders the adhesion of the polypropylene layer to the tab. A higher initial encapsulation temperature softens the oxide layer, allowing molten polypropylene to penetrate the oxide layer cracks and contact the fresh aluminum surface, forming a physicochemical bond. A shorter initial encapsulation time prevents the aluminum tab from being damaged or over-oxidized due to sustained high temperatures. The negative electrode tab is typically made of nickel or copper. Copper and nickel have much higher thermal conductivity than aluminum, allowing heat to be rapidly conducted along the tab body into the cell within the negative electrode tab area. A lower second encapsulation temperature reduces the temperature difference between the end cap and the negative electrode tab, slowing the heat conduction rate from the end cap to the tab, allowing heat to remain at the interface between the polypropylene layer and the tab for a longer period. Combined with a longer second encapsulation time, this gives the polypropylene layer sufficient time to fully melt and fill the microstructure of the tab surface. The non-tab area is the area where the two aluminum-plastic films are in direct contact. There is no thermal conduction effect from the tab metal strip. Its heat conduction path is significantly different from that of the tab area. It is thermo-sealed with an independent third packaging parameter group. The packaging parameters can be reasonably set according to the material properties and heat conduction conditions of this area, so that the packaging quality of the non-tab area is not affected by the parameter differences between the two tab areas.

[0018] The encapsulation of the positive electrode tab area, negative electrode tab area, and non-tab area is completed in parallel at the same workstation. The differentiated heat sealing parameters of the three areas are implemented synchronously in the same mold closing process without adding any additional process steps. This ensures the differentiated encapsulation effect of each area while maintaining the simplicity and efficiency of the top sealing process. Attached Figure Description

[0019] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, do not constitute an undue limitation of the invention.

[0020] Figure 1 A schematic cross-sectional view of the upper and lower end caps of the end cap for the top sealing of a soft-pack battery provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the sealing surfaces of the upper and lower sealing heads of a top seal for a soft-pack battery, provided in an embodiment of the present invention. Figure 3A schematic cross-sectional view of the upper and lower end caps of the end caps suitable for mass top sealing of soft-pack batteries, provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the sealing surfaces of the upper and lower sealing heads of the sealing heads for batch top sealing of soft-pack batteries, provided in an embodiment of the present invention.

[0021] The reference numerals in the figure are as follows: 1: Upper end cap; 2: Lower end cap; 3: Ear groove; 31: Middle area; 32: Transition section; 41: First ceramic insulation layer; 42: Second ceramic insulation layer; 51: Lateral pressure head section; 52: Top sealing pressure head section; 6: Head body. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this application, it should be noted that the terms "top", "end", "axial", "radial", etc., indicating orientation or positional relationship are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "fixing," etc., should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] Example 1: A cap suitable for top sealing of a pouch battery.

[0026] See Figure 1 , 2 .

[0027] This embodiment provides a top seal suitable for pouch batteries, including a rigid upper seal 1 and a lower seal 2 with good thermal conductivity. Optionally, but not limited to, the upper seal 1 and the lower seal 2 can be, but are not limited to, copper molds. A tab groove 3 is provided on the opposite surfaces of the upper seal 1 and the lower seal 2 to accommodate the tab area of ​​the battery cell. On the upper seal 1 and the lower seal 2, a partition groove is provided on both sides of each tab groove 3, and a first ceramic heat insulation layer 41 is embedded and fixed in each partition groove, which thermally isolates each tab groove 3 from its adjacent seal body 6. Independent heating elements and temperature detection elements are provided in the tab groove 3 area corresponding to the positive tab area, the tab groove 3 area corresponding to the negative tab area, and other seal areas (hereinafter referred to as the seal body 6) corresponding to non-tab areas. The temperature of each area is independently set and adjusted by a control system.

[0028] Regarding the dimensional fit, along the width direction of the tab, the width of the widest part of the tab groove 3 is greater than the width of the tab, and the width of the tab adhesive attached to both surfaces of the tab is greater than the width of the widest part of the tab groove 3. During mold closing, the tab metal strip and the tab adhesive on both sides are contained within the tab groove 3, and the tab adhesive exceeding the width of the tab groove 3 is pressed between the head bodies 6 corresponding to the non-tab areas of the upper and lower head, and sealed between the two opposing aluminum-plastic film layers.

[0029] Each tab groove 3 has a groove wall consisting of a central region 31 at the bottom and groove walls on both sides of the central region 31. Each side groove wall consists of two transition sections 32 that gradually rise outward from the central region 31 at an angle. The end of the outermost transition section 32 extends to the surface of the head body 6, so that the two ends of the bottom of the tab groove 3 smoothly transition to the surface of the head body 6. In the height direction, the groove depth at the central region 31 is greater than the thickness of the tab metal strip, and the depth of the position between the two transition sections 32 from the surface of the head body 6 is less than or equal to the thickness of the tab metal strip. In the width direction, the width of the central region 31 is less than the width of the tab metal strip, the distance between the positions of the two transition sections 32 on both sides of the same tab groove 3 is greater than or equal to the width of the tab metal strip contained in the tab groove 3, and the distance between the ends of the outermost transition sections 32 on both sides of the same tab groove 3 is greater than or equal to the width of the tab metal strip. With the above settings, the two ends of the bottom of the tab groove 3 gradually rise and extend to the surface of the end cap, forming a smooth transition, avoiding the problems of stress concentration and uneven glue overflow caused by the traditional right-angle stepped groove wall.

[0030] The beneficial effect of the end cap structure in this embodiment is that the area where the tab groove 3 corresponding to the positive tab area is located and the end cap body 6, and the area where the tab groove 3 corresponding to the negative tab area is located and the end cap body 6 are separated from each other by the first ceramic heat insulation layer 41, which has a thermal conductivity much lower than that of the end cap body 6. This achieves thermal isolation between the areas, significantly improves the temperature independent control accuracy of each area, and provides a structural basis for realizing the combination of differentiated heat sealing parameters for positive and negative electrodes.

[0031] In a preferred embodiment, a second ceramic heat insulation layer 42 is further provided on the upper end cap 1 and / or the lower end cap 2 of the aforementioned end cap, below the tab groove 3 corresponding to the negative tab region. This second ceramic heat insulation layer 42 forms a thermal resistance barrier in the heating path from the heating element to the tab groove 3, slowing down the conduction of heat along the tab thickness direction into the negative tab, allowing heat to diffuse laterally along the contact interface between the tab surface and the polypropylene layer. This enables the polypropylene layer to fully melt under lower temperature and longer time conditions, facilitating uniform heat sealing in the negative tab region.

[0032] In a preferred embodiment, on the upper end cap 1 and lower end cap 2 of the aforementioned end cap, lateral pressure head sections 51 extend in a direction perpendicular to the top sealing pressure head section 52 where the tab grooves 3 are located. The lateral pressure head sections 51 are parallel and directly opposite each other. During mold closing, the top sealing pressure head section 52 completes the heat sealing of the top sealing edge where the tabs are located. Simultaneously, at the intersection of the top sealing edge and the side sealing edge, the lateral pressure head sections 51 extend laterally along the battery cell, pressing the lateral aluminum-plastic film of the battery cell to form a lateral pre-sealing section of a certain length near the top sealing area. The lateral pre-sealing section is perpendicular to the top sealing area, defining the starting position for subsequent side final sealing. During side final sealing, the straight end of the side final seal is located within the lateral pre-sealing section, and the pressure block of the side final seal only contacts the surface of the aluminum-plastic film, not the outermost edge of the aluminum-plastic film, avoiding the problem of the polypropylene layer being squeezed out, contaminating the pressure block, and causing incomplete sealing.

[0033] Example 2: A top sealing head suitable for mass production of soft-pack batteries.

[0034] See Figure 3 , 4 .

[0035] This embodiment provides a top sealing head suitable for mass production of pouch batteries, comprising a rigid upper top sealing head 1 and a lower top sealing head 2 with good thermal conductivity. The upper top sealing head 1 and the lower top sealing head 2 are each sequentially integrated with a plurality of top sealing head units, the structure of each unit being the same as that of the top sealing head in Embodiment 1. On the opposing surfaces of the upper top sealing head 1 and the lower top sealing head 2, corresponding to the position of each top sealing head unit, a pair of vertically aligned tab grooves 3 are provided, each pair of tab grooves 3 corresponding to the positive tab region and the negative tab region of a battery cell.

[0036] Regarding the size fit, the width of the tab groove 3 of each end cap unit, the tab adhesive fit relationship, and the gradual transition structure of the groove wall are the same as in Embodiment 1, and will not be repeated here.

[0037] The advantages of this batch top-sealing head structure are as follows: During mold closing, the positive and negative tab areas of each battery cell are located within their respective tab grooves 3, allowing for complete coverage of all cells in a single mold closing operation, forming a continuous heat-sealing area on the top of the overall aluminum-plastic film. Compared to individual top-sealing, this batch top-sealing head significantly improves sealing efficiency. Furthermore, since each battery cell is encapsulated in the same mold closing process, the process parameters and environment are completely consistent, resulting in a substantial improvement in product consistency.

[0038] In a preferred embodiment, in the above-mentioned batch top sealing head structure, a second ceramic heat insulation layer 42 is further provided on the upper sealing head 1 and / or the lower sealing head 2 below the tab groove 3 corresponding to the negative tab area.

[0039] In a preferred embodiment, each end cap unit has two side pressure head sections 51 extending from the upper and lower end caps in a direction perpendicular to the top sealing pressure head section 52. The side pressure head sections 51 are parallel and facing each other. During mold closing, while the top sealing pressure head section 52 completes the heat sealing of each cell's tab area, the side pressure head sections 51 press together at the intersection of the top sealing edge and the side sealing edge of each cell along the side sealing direction to form a side pre-sealing section.

[0040] As an illustration of this embodiment, the heat-sealing width of each lateral pressure head section 51 in the batch top sealing head structure can be set to twice the width of the lateral pressure head section 51 in Embodiment 1, so that the lateral pre-sealing section formed by each lateral pressure head section 51 of the batch top sealing head is the common lateral heat-sealing section of two adjacent soft-pack cells, which can be cut along the centerline during the division.

[0041] Example 3: Top sealing process for pouch batteries.

[0042] This embodiment provides a top sealing process for a pouch battery, which can be implemented using, but is not limited to, the sealing head of Embodiment 1 or the batch top sealing head of Embodiment 2. The following description uses the sealing head of Embodiment 1 as an example. In the application scenario of batch top sealing, this process is implemented using the batch top sealing head of Embodiment 2.

[0043] The top sealing edge of a pouch battery includes a positive tab area, a negative tab area, and other areas located outside these two (i.e., the areas where the two aluminum-plastic films are in direct contact). The positive and negative tabs are led out from the cell body and sandwiched between the upper and lower aluminum-plastic films, the inner layer of which is a polypropylene layer. Both surfaces of the tab metal strips serving as the positive and negative tabs are coated with tab adhesive. During top sealing, the upper sealing head 1 and the lower sealing head 2 are heated and pressurized from both surfaces of the aluminum-plastic film, causing the polypropylene layer of the inner layer of the aluminum-plastic film to melt and fuse with the tab adhesive, sealing the top sealing edge at the tab end, forming the top sealing area.

[0044] During fabrication, a recess is punched into an aluminum-plastic film to form a cavity for housing the battery cell. The battery cell is then inserted into the cavity, with the two tabs extending from the cavity to the edge of the aluminum-plastic film. The protruding ends of the battery cell's tabs are designated as the top. The aluminum-plastic film is folded along the bottom of the cavity, covering the top of the cavity and aligning it with the aluminum-plastic film layer containing the cavity, forming two opposing layers of aluminum-plastic film. The battery cell is positioned between these two layers for encapsulation. The top sealing edge of the pouch battery to be encapsulated is placed between the upper sealing head 1 and the lower sealing head 2. The upper sealing head 1 is driven to close with the lower sealing head 2. During mold closing, the positive tab area is heat-sealed using the first encapsulation parameter set, the negative tab area is heat-sealed using the second encapsulation parameter set, and the remaining areas of the top sealing edge are heat-sealed using the third encapsulation parameter set. This completes the top sealing of the pouch battery using a hard-sealing process.

[0045] The first packaging parameter set includes a first packaging temperature and a first packaging time, and the second packaging parameter set includes a second packaging temperature and a second packaging time. The first packaging temperature is higher than the second packaging temperature, and the first packaging time is shorter than the second packaging time. That is, the positive electrode area is thermo-sealed with a higher first packaging temperature and a shorter first packaging time. During the research of this invention, the inventors discovered that the positive electrode is made of aluminum, and its dense oxide layer hinders the adhesion between the polypropylene layer and the electrode. Using a higher first packaging temperature can instantly soften the oxide layer, allowing the molten polypropylene material to penetrate the cracks in the oxide layer and contact the fresh aluminum surface, forming a physical and chemical bond, effectively improving the packaging strength of the positive electrode area. Using a shorter first packaging time can prevent the aluminum electrode from being damaged or over-oxidized due to continuous high temperatures.

[0046] For the negative tab area, thermosealing is performed with a lower second encapsulation temperature and a longer second encapsulation time. The negative tab is made of nickel or copper. Copper and nickel have much higher thermal conductivity than aluminum, so heat will be rapidly conducted from the negative tab area along the tab body into the cell. If the second encapsulation temperature is too high, the heat transferred by the heating element will be quickly absorbed by the highly thermally conductive negative tab and conducted longitudinally along the tab into the cell. This results in the actual temperature of the contact interface between the PP layer and the tab being much lower than the encapsulation set temperature. The PP will cool and solidify due to heat loss before it has fully melted. Using a lower second temperature reduces the temperature difference between the end cap and the negative tab. When the end cap temperature is close to the tab body temperature, the heat conduction rate from the end cap to the tab is significantly reduced. The heat will not be lost rapidly but will remain at the contact interface between the PP layer and the tab for a longer time. Combined with a longer second heat sealing time, this gives the PP layer sufficient time to fully melt and fill the microstructure of the tab surface.

[0047] For the other sealing areas of the top sealing edge, the two layers of aluminum-plastic film are in direct contact, and there is no thermal influence from the tab metal strip. Its heat conduction path is significantly different from that of the tab area. It is heat-pressed and sealed with an independent third packaging parameter group. The third packaging parameter group can be reasonably set according to the material characteristics and heat conduction conditions of the area itself.

[0048] As can be seen from the above, the packaging of the positive tab area, the negative tab area, and other areas is completed in parallel at the same workstation. The differentiated heat sealing parameters of the three areas are implemented synchronously in the same mold closing process without adding any additional process steps. While ensuring differentiated packaging of each area, the simplicity and efficiency of the top sealing process are maintained.

[0049] In a preferred embodiment, the first heat-sealing pressure for the positive electrode tab region is greater than the second heat-sealing pressure for the negative electrode tab region. More preferably, the first heat-sealing pressure for the positive electrode tab region is 0.4 MPa to 0.6 MPa, and the second heat-sealing pressure for the negative electrode tab region is 0.3 MPa to 0.45 MPa. Using a higher first sealing pressure for the positive electrode tab region helps ensure that the polypropylene layer fully fills the micro-uneven structure of the aluminum electrode tab surface in the molten state, enhancing the mechanical interlocking effect. Using a lower second sealing pressure for the negative electrode tab region avoids deformation of the copper or nickel electrode tabs at high temperatures due to excessive pressure. By using a high first sealing pressure, a high first sealing temperature, and a short first sealing time for the positive electrode, and a lower second sealing pressure, a lower second sealing temperature, and a longer second sealing time for the negative electrode, the three-dimensional parameters of pressure, temperature, and time work synergistically to achieve reliable sealing of both the aluminum electrode tab and the copper / nickel electrode tab in the same molding process.

[0050] In a preferred embodiment, prior to hot-press sealing, the surface of the positive electrode tab in contact with the polypropylene layer of the aluminum-plastic film is further roughened to form a micron-level uneven structure on the surface of the positive electrode tab. This roughening treatment can be achieved through methods such as sandblasting, chemical etching, or laser etching, forming a uniformly distributed micron-level uneven structure on the electrode tab surface. This significantly increases the effective contact area between the aluminum electrode tab surface and the polypropylene layer of the aluminum-plastic film, enhancing the mechanical interlocking effect between the polypropylene layer and the electrode tab. The molten polypropylene material penetrates into the gaps of the uneven structure, and after cooling and solidification, forms physical anchoring points, effectively improving the encapsulation strength of the positive electrode tab area.

[0051] In a preferred embodiment, a second ceramic heat insulation layer 42 is further provided on the upper end cap 1 and / or the lower end cap 2 below the tab groove 3 corresponding to the negative tab region. The second ceramic heat insulation layer 42 can be made of alumina, aluminum nitride, etc. The second ceramic heat insulation layer 42 forms a thermal resistance barrier in the heating path, slowing down the conduction of heat along the thickness direction of the tab to the interior of the negative tab, and allowing heat to diffuse laterally along the contact interface between the tab surface and the polypropylene layer, which is beneficial for uniform heat sealing in the negative tab region.

[0052] In a preferred embodiment, during the hot-press sealing of the top edge, lateral pre-sealing sections are formed at each intersection of the top edge and the two side edges along the side-sealing direction. These lateral pre-sealing sections extend from both ends of the top edge along the side-sealing direction. The lateral pre-sealing sections pre-define the starting position for the subsequent final side sealing: during final side sealing, the end of the sealing section is located within the lateral pre-sealing area, without touching the edge line of the side edge. The pressure block for final side sealing only contacts the surface of the aluminum-plastic film, not its outer edge, thus avoiding the problem of the polypropylene layer being squeezed out and contaminating the pressure block, leading to a false seal.

[0053] As a preferred embodiment, this process is implemented using a batch top-sealing method, and the end cap can be the end cap shown in Example 2, suitable for batch top-sealing of soft-pack batteries. During preparation, a plurality of parallel recesses are stamped into a monolithic aluminum-plastic film. Each battery cell is inserted into its corresponding recess, with the positive and negative tabs of each cell extending from the top edge of each recess. The aluminum-plastic film is folded along the bottom edge of all recesses to cover them, with each battery cell positioned between two opposing layers of aluminum-plastic film for batch packaging. During mold closing, the positive and negative tab areas of each battery cell are located within their corresponding tab grooves 3. The positive tab areas are heat-sealed using a first packaging parameter set, the negative tab areas are heat-sealed using a second packaging parameter set, and the other areas are heat-sealed using a third packaging parameter set. A continuous heat-sealed area is formed at the top of the monolithic aluminum-plastic film during the single mold closing process. After the batch top sealing is completed, the side-connected pouch cells are divided into individual pouch cells, and each is subjected to side final sealing, followed by electrolyte injection and capacity testing to obtain the finished product. Using the process in this embodiment, the top sealing of multiple pouch cells can be completed at one time, and the top sealing process parameters and top sealing environment of each cell are completely consistent, which greatly improves the consistency of top sealing and production efficiency.

[0054] Example 1a, wherein the first encapsulation temperature is 190°C and the first encapsulation time is 2.5s.

[0055] In this embodiment, the first encapsulation temperature is 190℃, and the first encapsulation time is 2.5s. Under these parameters, the encapsulation strength of the positive electrode area is measured to be approximately 54N / 15mm.

[0056] Example 1b, wherein the first encapsulation temperature is 200°C and the first encapsulation time is 2.0s.

[0057] In this embodiment, the first encapsulation temperature is 200℃, and the first encapsulation time is 2.0s. Under these parameters, the encapsulation strength of the positive electrode area is measured to be approximately 58N / 15mm.

[0058] Example 1c, wherein the first packaging temperature is 210°C and the first packaging time is 1.5s.

[0059] In this embodiment, the first encapsulation temperature is 210℃, and the first encapsulation time is 1.5s. Under these parameters, the encapsulation strength of the positive electrode area is approximately 60N / 15mm.

[0060] In the three embodiments described above, the encapsulation strength of the positive electrode area is significantly higher than the industry standard requirement (≥20N / 15mm).

[0061] Example 2a, wherein the second encapsulation temperature is 150°C and the second encapsulation time is 4.5s.

[0062] In this embodiment, the second encapsulation temperature is 150°C, and the second encapsulation time is 4.5 seconds. Under these parameters, the encapsulation strength of the negative electrode tab region is measured to be approximately 52 N / 15 mm.

[0063] Example 2b, wherein the second encapsulation temperature is 160°C and the second encapsulation time is 3.8s.

[0064] In this embodiment, the second encapsulation temperature is 160°C, and the second encapsulation time is 3.8 seconds. Under these parameters, the encapsulation strength of the negative electrode tab region is measured to be approximately 55 N / 15 mm.

[0065] Example 2c, wherein the second packaging temperature is 170°C and the second packaging time is 3.0s.

[0066] In this embodiment, the second encapsulation temperature is 170°C, and the second encapsulation time is 3.0 s. Under these parameters, the encapsulation strength of the negative electrode tab region is measured to be approximately 57 N / 15 mm.

[0067] In all three embodiments, the encapsulation strength of the negative electrode tab region is significantly higher than the industry standard requirement (≥20N / 15mm). Observation of the encapsulation interface cross-sectional morphology in each embodiment shows that the polypropylene layer is fully fused, the interface is dense, and there are no obvious defects.

[0068] Example 3a, wherein the third encapsulation temperature is 160°C and the third encapsulation time is 3.5s.

[0069] In this embodiment, the third encapsulation temperature is 160°C, and the third encapsulation time is 3.5 seconds. Under these parameters, the encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact is measured to be approximately 48 N / 15 mm.

[0070] Example 3b, wherein the third encapsulation temperature is 175°C and the third encapsulation time is 2.8s.

[0071] In this embodiment, the third encapsulation temperature is 175°C, and the third encapsulation time is 2.8 seconds. Under these parameters, the encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact is measured to be approximately 50 N / 15 mm.

[0072] Example 3c, wherein the third encapsulation temperature is 190°C and the third encapsulation time is 2.0s.

[0073] In this embodiment, the third encapsulation temperature is 190℃, and the third encapsulation time is 2.0s. Under these parameters, the encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact is measured to be approximately 52N / 15mm.

[0074] In the above three embodiments, the sealing strength of the sealing area where the two aluminum-plastic films are in direct contact meets or exceeds the requirements of the top / side sealing strength in the industry standard (≥40N / 15mm).

[0075] Experimental examples and comparative experimental data: To verify the technical solution of this application, which applies different encapsulation temperatures and times to the positive electrode tab area, negative electrode tab area, and the area in direct contact between the two aluminum-plastic films in the same top-sealing molding process, and to demonstrate its beneficial effects compared to the existing unified heat sealing parameter scheme for positive and negative electrodes and the existing preheating compensation scheme, the following sample cells were prepared: Example Combination 1 (corresponding to Examples 1a, 2a, 3a), Example Combination 2 (corresponding to Examples 1b, 2b, 3b), Example Combination 3 (corresponding to Examples 1c, 2c, 3c), and Control Example Group 1 (traditional unified parameter scheme), Control Example Group 2 (hard sealing scheme with the same parameters for positive and negative electrodes), and Control Example Group 3 (hard sealing scheme with unified parameters after preheating). 100 battery cell samples were prepared for each experimental group.

[0076] The parameter settings for each experimental group are as follows: Example combination one (corresponding to Examples 1a, 2a, and 3a): First encapsulation temperature 190℃, first encapsulation time 2.5s; second encapsulation temperature 150℃, second encapsulation time 4.5s; third encapsulation temperature 160℃, third encapsulation time 3.5s. Hard sealing process was used, and the encapsulation pressure was uniformly 0.5MPa.

[0077] Example combination two (corresponding to Examples 1b, 2b, and 3b): First encapsulation temperature 200℃, first encapsulation time 2.0s; second encapsulation temperature 160℃, second encapsulation time 3.8s; third encapsulation temperature 175℃, third encapsulation time 2.8s. Implemented using a hard-sealing process, with a uniform encapsulation pressure of 0.5MPa.

[0078] Example combination three (corresponding to Examples 1c, 2c, and 3c): First encapsulation temperature 210℃, first encapsulation time 1.5s; second encapsulation temperature 170℃, second encapsulation time 3.0s; third encapsulation temperature 190℃, third encapsulation time 2.0s. Implemented using a hard-sealing process, with a uniform encapsulation pressure of 0.5MPa.

[0079] Comparative Example Group 1 (Traditional Unified Parameters): The same encapsulation parameters were used for thermo-sealing of the positive tab area, the negative tab area, and the area where the two aluminum-plastic films directly contacted. The encapsulation temperature was uniformly 180℃, the encapsulation time was uniformly 3.0s, and the encapsulation pressure was uniformly 0.5MPa.

[0080] Comparative Example Group 2 (Same parameters for positive and negative electrodes in hard sealing): The same encapsulation parameters are used for the positive electrode tab area, the negative electrode tab area, and the area where the two aluminum-plastic films are in direct contact, and the hard sealing process is used for thermo-press sealing. The hard sealing process is carried out using a copper mold head with tab grooves and limiting height. The encapsulation temperature is uniformly 180℃, the encapsulation time is uniformly 3.0s, and the encapsulation pressure is uniformly 0.5MPa.

[0081] Comparative Example Group 3 (Unified Parameter Hard Sealing Scheme after Preheating): First, the positive electrode tab (aluminum material) is preheated to 200°C using an auxiliary heating element, so that the temperature of the positive electrode tab is similar to that of the negative electrode tab; then, the positive electrode tab area, the negative electrode tab area, and the sealing area where the two layers of aluminum-plastic film are in direct contact are hard sealed with the same sealing parameters, with the sealing temperature uniformly set at 180°C, the sealing time uniformly set at 3.0s, and the sealing pressure uniformly set at 0.5MPa.

[0082] I. Sample preparation.

[0083] Using aluminum-plastic film, positive electrode tabs (aluminum), negative electrode tabs (nickel or copper), and cell body materials from the same batch, cell samples for each experimental group were prepared. The aluminum-plastic film model, cell body size, and capacity design were identical across all experimental groups; the only variable was the top sealing process parameters. In Control Group 3, the preheating step was completed before top sealing and mold closing. The positive electrode tab was preheated using an auxiliary heating element, and top sealing and mold closing were performed immediately after preheating.

[0084] II. Testing Methods.

[0085] Encapsulation strength test: 20 battery cell samples were taken from each experimental group, and 15mm wide samples (both the positive and negative tab areas) were cut from the seals of each cell. The peel force was tested on a tensile testing machine at a 180° peel angle. The tab area was evaluated according to the industry standard requirement of tab encapsulation strength ≥20N / 15mm, and the sealing area where the two aluminum-plastic films are in direct contact was evaluated according to the top / side seal encapsulation strength requirement of ≥40N / 15mm.

[0086] Leakage test: 20 battery cell samples were taken from each experimental group, and the leakage rate was detected using a helium mass spectrometer in a vacuum chamber method. The detection sensitivity was 1×10⁻⁻⁻⁶. 9 On the order of Pa·m³ / s.

[0087] Cross-sectional micromorphology observation: Five cell samples were taken from each experimental group, and cross-sectional sections were prepared for sealing the positive and negative tab areas. The fusion state of the encapsulation interface was observed under an optical microscope to check for encapsulation defects such as bubbles and delamination.

[0088] III. Test Results.

[0089] Table 1: Comparison of test results between the example combination and the main control group: Encapsulation strength of the positive tab region 180° peel test, sample width 15mm 38N / 15mm 40N / 15mm 48N / 15mm 58N / 15mm Encapsulation strength of the negative electrode area Same as above 42N / 15mm 44N / 15mm 43N / 15mm 55N / 15mm Encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact Same as above 45N / 15mm 46N / 15mm 46N / 15mm 50N / 15mm Helium leakage rate (Pa·m³ / s) Vacuum chamber method for helium detection <![CDATA[1.2×10⁻ 8 ]]> <![CDATA[1.0×10⁻ 8 ]]> <![CDATA[7.0×10⁻ 9 ]]> <![CDATA[3.5×10⁻ 9 ]]> Cross-sectional morphology of the positive electrode ear region Optical microscopy observation The interface is layered, and bubbles are visible in some areas. Melting is acceptable, with occasional tiny bubbles. It melts well and has no obvious bubbles. The interface is dense and has no obvious defects. Cross-sectional morphology of the negative electrode ear region Same as above The melting was relatively complete, with occasional tiny bubbles. The melting was relatively complete, with occasional tiny bubbles. The melting was relatively complete, with occasional tiny bubbles. Fully melted, with a dense interface .

[0090] Table 2: Comparison of test results among the three sets of example combinations: Encapsulation strength of the positive tab region 180° peel test, sample width 15mm 54N / 15mm 58N / 15mm 60N / 15mm Encapsulation strength of the negative electrode area Same as above 52N / 15mm 55N / 15mm 57N / 15mm Encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact Same as above 48N / 15mm 50N / 15mm 52N / 15mm Helium leakage rate (Pa·m³ / s) Vacuum chamber method for helium detection <![CDATA[3.8×10⁻ 9 ]]> <![CDATA[3.5×10⁻ 9 ]]> <![CDATA[3.8×10⁻ 9 ]]> Cross-sectional morphology of the positive electrode ear region Optical microscopy observation The interface is dense and has no obvious defects. The interface is dense and has no obvious defects. The interface is dense and has no obvious defects. Cross-sectional morphology of the negative electrode ear region Same as above Fully melted, with a dense interface Fully melted, with a dense interface Fully melted, with a dense interface .

[0091] Table 3: Comparison of test results between Example Combinations 4 and 5 and Example Combination 2: Encapsulation strength of the positive tab region 180° peel test, sample width 15mm 57N / 15mm 39N / 15mm 58N / 15mm Encapsulation strength of the negative electrode area Same as above 42N / 15mm 56N / 15mm 55N / 15mm Encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact Same as above 46N / 15mm 46N / 15mm 50N / 15mm Helium leakage rate (Pa·m³ / s) Vacuum chamber method for helium detection <![CDATA[1.0×10⁻ 8 ]]> <![CDATA[9.0×10⁻ 9 ]]> <![CDATA[3.5×10⁻ 9 ]]> Cross-sectional morphology of the positive electrode ear region Optical microscopy observation The interface is dense and has no obvious defects. The interface is layered, and bubbles are visible in some areas. The interface is dense and has no obvious defects. Cross-sectional morphology of the negative electrode ear region Same as above The melting was relatively complete, with occasional tiny bubbles. Fully melted, with a dense interface Fully melted, with a dense interface .

[0092] IV. Results Analysis.

[0093] (I) A comparison of Tables 1, 2, and 3 shows that: In Comparative Example 1 (traditional uniform parameters), the encapsulation strength of the positive tab area is only about 38 N / 15 mm, and delamination and bubble defects exist in the cross-section of the positive tab area. In Comparative Example 2, the encapsulation strength of the positive tab area is about 40 N / 15 mm, only slightly improved compared to Comparative Example 1, and small bubbles are still occasionally seen in the cross-sectional morphology. This indicates that simply changing the process from conventional heat sealing to hard sealing has limited overall improvement in encapsulation effect. In Comparative Example 3, by preheating the positive tab to make its temperature consistent with that of the negative tab and then hard sealing with uniform parameters, the encapsulation strength of the positive tab area is about 48 N / 15 mm, which is improved compared to both Comparative Example 1 and Comparative Example 2. However, the encapsulation strength of its negative tab area is about 43 N / 15 mm, basically the same as that of Comparative Example 1 and Comparative Example 2, and the helium leakage rate is still lower than that of Example Combination 2. Although the preheating compensation scheme improves the encapsulation effect of the positive tab area, the encapsulation effect of the negative tab area is not improved simultaneously.

[0094] As shown in Table 3, in Example Combination 4 (differentiation only of the positive electrode), the encapsulation strength of the positive electrode tab region is approximately 57 N / 15 mm, but the encapsulation strength of the negative electrode tab region is only approximately 42 N / 15 mm. In Example Combination 5 (differentiation only of the negative electrode), the encapsulation strength of the negative electrode tab region is approximately 56 N / 15 mm, but the encapsulation strength of the positive electrode tab region is only approximately 39 N / 15 mm. The helium leakage rate of both groups is higher than that of Example Combination 2. The effect produced by the combination of high temperature for short time on the positive electrode and low temperature for long time on the negative electrode is something that cannot be achieved by simply differentiating the positive electrode or simply differentiating the negative electrode. As shown in Table 2, the encapsulation strength of the positive tab region in all three sets of examples is higher than that of all three control examples, and the encapsulation strength of the negative tab region is also higher than that of all three control examples. The helium leakage rate is also better than that of all three control examples.

[0095] (II) As can be seen from the comparison in Table 2, the three sets of example combinations correspond to the parameter combinations of Examples 1a, 2a, 3a, 1b, 2b, 3b, 1c, 2c, and 3c, respectively. As the positive electrode temperature increases from 190℃ to 210℃, the encapsulation strength of the positive electrode tab region gradually increases from approximately 54N / 15mm to 60N / 15mm. The helium leakage rate of Example Combination 2 is approximately 3.5×10⁻⁻⁻⁶. 9 This is superior to the approximately 3.8 × 10⁻ of the first embodiment. 9 Approximately 3.8 × 10⁻ in combination with Example 3 9 In the high-temperature, short-time strategy for the positive electrode, higher temperatures lead to more thorough damage to the oxide layer. However, in the low-temperature, long-time strategy for the negative electrode, while excessively low temperatures can prevent premature curing of the polypropylene layer, they require a longer time to compensate for the high thermal conductivity; excessively high temperatures may cause premature curing of the polypropylene layer in the negative electrode. These two approaches are inversely related, and parameter selection requires a trade-off between these two opposing strategies. The intermediate parameters of Example Combination Two achieved a better balance between the encapsulation strength of the positive and negative electrodes, while also obtaining a lower helium leakage rate.

[0096] (III) As can be seen from the comparison of Tables 1 and 3: Based on all the experimental data in Tables 1 to 3, Example Combination 2 (intermediate parameters) shows good overall performance in all test indicators: the encapsulation strength of the positive tab area is about 58 N / 15 mm, the encapsulation strength of the negative tab area is about 55 N / 15 mm, the encapsulation strength of the sealing area where the two aluminum-plastic films are in direct contact is about 50 N / 15 mm, and the helium leakage rate is about 3.5 × 10⁻ 9 The cross-sectional morphology of both examples showed a dense interface with no obvious defects. The helium leakage rates of combinations four and five in examples were approximately 1.0 × 10⁻ ... 8 Approximately 9.0 x 10⁻ 9 The value was significantly higher than that of Example Combination 2, indicating a synergistic effect between the positive and negative electrode differentiation strategies.

[0097] It should be noted that, in the description of this specification, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with an embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A top sealing process of a pouch battery, characterized by, include: Place the top sealing edge of the soft-pack battery to be packaged between the upper and lower sealing heads of the top sealing equipment; The upper end cap is driven to close with the lower end cap, and the positive tab area of ​​the soft pack battery is heat-sealed with the first packaging parameter group, the negative tab area of ​​the soft pack battery is heat-sealed with the second packaging parameter group, and the other areas except the positive tab area and the negative tab area are heat-sealed with the third packaging parameter group. The first packaging parameter set includes a first packaging temperature and a first packaging time, and the second packaging parameter set includes a second packaging temperature and a second packaging time; the first packaging temperature is higher than the second packaging temperature, and the first packaging time is shorter than the second packaging time.

2. The top sealing process of a pouch battery according to claim 1, wherein The first encapsulation temperature is 190°C to 210°C, and the first encapsulation time is 1.5s to 2.5s.

3. The top sealing process of a pouch battery according to claim 1, wherein, The second encapsulation temperature is 150°C to 170°C, and the second encapsulation time is 3.0s to 4.5s.

4. The top sealing process for the soft-pack battery according to claim 1, characterized in that, The third encapsulation temperature is 160°C to 190°C, and the third encapsulation time is 2.0s to 3.5s.

5. The top sealing process for the soft-pack battery according to claim 1, characterized in that, The heat sealing pressure for the positive electrode tab region is greater than the heat sealing pressure for the negative electrode tab region.

6. The top sealing process of a pouch battery according to claim 5, wherein The heat sealing pressure for the positive electrode tab region is 0.4 MPa to 0.6 MPa, and the heat sealing pressure for the negative electrode tab region is 0.3 MPa to 0.45 MPa.

7. The top sealing process of a pouch battery according to claim 1, wherein Before the hot-press sealing, the surface of the positive electrode tab that contacts the aluminum-plastic film polypropylene layer is roughened to form a micron-level uneven structure.

8. The top sealing process of a pouch battery according to claim 1, wherein, A second ceramic heat insulation layer is also provided below the tab groove of the upper end cap and / or the lower end cap corresponding to the negative electrode tab area.

9. The top sealing process for the soft-pack battery according to claim 1, characterized in that, When the top sealing edge is hot-pressed and sealed, a lateral pre-sealing section is also formed at each intersection of the top sealing edge and the two side sealing edges along the side sealing direction. The two lateral pre-sealing sections extend from both ends of the top sealing edge along the side sealing direction.

10. The top sealing process of a pouch battery according to claim 1, wherein Before the hot-press sealing, a plurality of parallel recesses are stamped on an integral aluminum-plastic film. Each battery cell is installed in one of the recesses, and the positive and negative tabs of each battery cell extend out from the top of each recess. The bottom of the aluminum-plastic film is folded over to cover each recess. The upper and lower end caps are provided with a plurality of pairs of tab grooves along their length. The tab grooves on the upper and lower end caps are directly opposite each other, and each pair of tab grooves corresponds to the two tabs of one battery cell. During mold closing, each of the positive and negative tab regions of each of the battery cells is located in the tab groove. The positive tab regions are heat-sealed using the first packaging parameter set, while the negative tab regions are heat-sealed using the second packaging parameter set. The other regions, excluding the positive and negative tab regions, are heat-sealed using the third packaging parameter set. A continuous heat-sealed area is formed on the top of the overall aluminum-plastic film during the mold closing process.

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