Soft package battery structure

Abstract

The utility model discloses a soft package battery structure which comprises a naked battery cell, the naked battery cell comprises a plurality of pole pieces, and the parts, extending out of the naked battery cell, of the pole pieces are foil pole lugs; the tab group comprises a plurality of foils which are stacked together, and the plurality of foils are respectively connected with the corresponding foil tabs; the aluminum-plastic film assembly is used for accommodating the naked battery cell, the aluminum-plastic film assembly comprises a packaging edge, the packaging edge is connected with the foil close to one end of the naked battery cell, and the tab group extends out of the packaging edge and is used for being electrically connected with the outside. According to the utility model, the thickness of the foil is thinner than that of the outer tab, and when the single foil is welded with the single foil tab, the required welding energy is relatively small, and the hot melting area is relatively small, so that the welding area when the foil tab is welded with the foil can be reduced, and the length of the foil tab along the length direction of the pole piece can be shortened; the volume of the area in the battery cell is reduced, and the volume energy density of the battery cell is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a soft-pack battery structure. Background Technology

[0002] A pouch battery is a lithium-ion battery that uses an aluminum-plastic composite film (abbreviated as aluminum-plastic film) as its outer casing material. Compared with traditional hard-shell batteries (such as steel or aluminum casings), pouch batteries have higher energy density, a lighter and more compact shape, and better flexibility, and are therefore widely used in products that pursue high performance and miniaturization.

[0003] Currently, in the manufacturing of pouch cells, an 8-10 mm blank foil area, also known as a foil tab, is typically reserved outside the electrode coating area. After multiple layers of electrodes are stacked or wound, the outer tabs of the multiple foil tabs need to be welded together. Finally, the outer tabs are heat-sealed with an aluminum-plastic film using tab adhesive, thus achieving the sealed encapsulation of the pouch cell. However, because welding the multiple foil tabs to the outer tabs, which are thicker than the foil, requires greater welding energy to weld them together, the heat-affected zone at the welding point is relatively large. Therefore, the length of the welding point along the electrode length needs to be longer, thus occupying more cell volume and reducing the cell's volumetric energy density.

[0004] Therefore, this application aims to propose a pouch battery structure to solve the above-mentioned problems. Utility Model Content

[0005] The main objective of this invention is to provide a soft-pack battery structure that addresses the technical problem in the prior art where the welding area between the foil tabs and the outer tabs in multilayer electrode sheets is large, occupies a significant amount of cell volume, and reduces the volumetric energy density of the cell.

[0006] To achieve the aforementioned utility model objectives, this utility model proposes a soft-pack battery structure, including a bare cell, wherein the bare cell includes multiple electrode sheets, and the portions of the electrode sheets extending beyond the bare cell at both ends are foil tabs; a tab assembly, including multiple stacked foil sheets, each of which is connected to its corresponding foil tab; and an aluminum-plastic film assembly for housing the bare cell, the aluminum-plastic film assembly including an encapsulation edge, the encapsulation edge being connected to the foil sheet near one end of the bare cell, and the tab assembly extending beyond the encapsulation edge for external electrical connection.

[0007] Furthermore, adjacent foil sheets are hot-pressed together by an adhesive layer.

[0008] Furthermore, the thickness of the adhesive layer ranges from 1 to 20 micrometers.

[0009] Furthermore, a first connecting area and a second connecting area are provided on the two large surfaces of the foil, and the adhesive layer is disposed between the first connecting area and the second connecting area. The foil is connected to the foil tab through the first connecting area.

[0010] Furthermore, the encapsulation edge of the aluminum-plastic film assembly is heat-sealed with the tab assembly using an adhesive layer.

[0011] Furthermore, the length of the foil tab along the length direction of the electrode sheet ranges from 1 to 4 millimeters.

[0012] Furthermore, the aluminum-plastic film assembly includes an upper aluminum-plastic film and a lower aluminum-plastic film, both of which are connected to the portion of the foil where an adhesive layer is provided, thus encapsulating the bare battery cell.

[0013] Furthermore, both the upper and lower aluminum-plastic films are provided with grooves that match the bare battery cells, and the grooves are used to accommodate the bare battery cells.

[0014] Furthermore, the opening edges of the grooves in the upper and lower aluminum-plastic films extend away from the side of the grooves to form the encapsulation edges of the upper and lower aluminum-plastic films.

[0015] Furthermore, a fireproof layer is provided inside the groove.

[0016] Beneficial effects:

[0017] Compared with the prior art, a soft-pack battery structure according to an embodiment of this application includes a bare cell, which includes multiple electrodes, with the two ends of the electrodes extending out of the bare cell forming foil tabs; foils corresponding to the multiple electrodes, each foil being connected to its corresponding foil tab; and an aluminum-plastic film assembly for housing the bare cell. The aluminum-plastic film assembly includes an encapsulation edge, which is connected to the foil near one end of the bare cell. The foil extends out of the encapsulation edge for external electrical connection. This technical solution replaces the external tabs with foil tabs for connection. Since the foil is thinner than the external tab, the welding energy required when welding a single foil to a single foil tab is relatively small, and the hot-melt area is relatively small. Therefore, the welding area when welding the foil tab to the foil can be reduced, thereby shortening the length of the foil tab along the length of the electrode, reducing the volume occupied by this area inside the cell, and improving the volumetric energy density of the cell. Attached Figure Description

[0018] Figure 1 This is an exploded view of the soft-pack battery structure in one embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram showing the connection between the electrode sheet and the foil sheet in one embodiment of the present invention;

[0020] Figure 3 for Figure 1 Enlarged view of point I in the middle;

[0021] Figure 4 This is a three-dimensional schematic diagram of the polar coil extension and foil connection in one embodiment of the present invention;

[0022] Figure 5 This is a three-dimensional schematic diagram of the polar roll extension and foil connection in another embodiment of the present invention.

[0023] in:

[0024] 1. Soft-pack battery structure; 10. Bare cell; 100. Electrode sheet; 1000. Foil tab; 11. Aluminum-plastic film assembly; 110. Upper aluminum-plastic film; 1100. Encapsulation edge; 111. Lower aluminum-plastic film; 1111. Groove; 12. Foil sheet; 120. Tab assembly; 121. Tab adhesive; 122. Adhesive layer; 123. First connection area; 124. Second connection area.

[0025] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They 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 utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly and specifically defined.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] Please see Figures 1 to 5 In this embodiment, a soft-pack battery structure is provided, including a bare cell 10, which includes multiple electrode sheets 100, the two ends of which extend out of the bare cell 10 to form foil tabs 1000; a tab assembly 120, which includes multiple stacked foil sheets 12, each of which is connected to its corresponding foil tab 1000; and an aluminum-plastic film assembly 11, which is used to house the bare cell 10, the aluminum-plastic film assembly 11 including an encapsulation edge 1100, the encapsulation edge 1100 being connected to the foil sheet 12 near one end of the bare cell 10, and the tab assembly 120 extending out of the encapsulation edge 1100 for external electrical connection.

[0031] In this embodiment, each electrode 100 has foil tabs 1000 extending outward at both ends. The electrode 100 includes a positive electrode 100 and a negative electrode 100. A diaphragm is provided between the positive electrode 100 and the negative electrode 100. The positive electrode 100 and the negative electrode 100 are stacked or wound to form a bare cell 10.

[0032] It should be noted that in the traditional assembly process of a bare cell 10, multiple foil tabs 100 of the electrode sheets 100 need to be ultrasonically welded or laser-welded together to form the inner tab of the bare cell 10. In this soft-pack battery structure 1, by welding the foil tabs 1000 of multiple electrode sheets 100 together, the resistance can be effectively reduced and the current conduction performance of the battery can be improved. Current can be conducted unimpeded from one electrode sheet 100 to another, reducing resistance and energy loss, thereby improving the battery efficiency. The aluminum-plastic film assembly 11 is used to house the bare cell 10 and is sealed to the outer tab by the adhesive layer 122 between the encapsulation edge 1100 and the outer tab. However, since the outer tab is used to connect to the external circuit, its current-carrying area cannot be too small, and it generally needs to be connected to the external circuit by welding. Therefore, the outer tab is usually relatively thick. When connecting to multiple foil tabs 1000 welded together, the outer tab needs to be stacked with multiple layers of foil tabs 1000, and the connection is made using laser welding or ultrasonic welding. Specifically, when using laser welding, the required welding energy is relatively large to penetrate the outer tab, and the heat-affected zone of the molten pool is relatively large. Therefore, an 8 to 10 mm allowance needs to be reserved in the length of the foil tabs 1000 along the length of the electrode sheet 100 for welding the foil tabs 1000 to the outer tab after stacking. When using ultrasonic welding, the welding of the multiple layers of foil tabs 1000 to the outer tab includes welding between foil tabs 1000 and welding the foil tabs 1000 to the outer tab. The heat-affected zone is also relatively large, and an 8 to 10 mm allowance also needs to be reserved in the length of the foil tabs 1000 along the length of the electrode sheet 100 for welding the foil tabs 1000 to the outer tab after stacking. In the packaging of pouch batteries, the area of ​​the foil tabs 1000 used for welding is also within the aluminum-plastic film packaging space, thus occupying the volume of the cell and reducing its volumetric energy density. To solve this problem, some technical solutions propose not using external tabs, but directly setting tab adhesive 121 on multiple stacked foil tabs 1000 near the bare cell 10. The foil tabs 1000 are then directly heat-fused to the aluminum-plastic film assembly 11, which solves the technical problem of the welding area of ​​the foil tabs 1000 being within the aluminum-plastic film packaging space, occupying the cell volume and reducing its volumetric energy density. However, the above technical solutions have significant drawbacks in the actual manufacturing stage. When multiple foil tabs 1000 are stacked or wound to form the bare cell 10, an adhesive layer needs to be set on the foil tabs 1000, increasing the manufacturing process of the bare cell 10. This requires additional equipment and manual inspection steps, significantly increasing manufacturing costs. Furthermore, the adhesive layer is usually placed on the foil tab 1000 near the bare cell 10. After encapsulation, the foil tab 1000 is directly led out to the outside. When the cell is in use, the current is easily concentrated on the foil tab 1000 near the bare cell 10, which accelerates the aging of the tab adhesive 121 and affects the use of the cell.

[0033] To address the issues of the foil tabs 1000 occupying space within the aluminum-plastic film encapsulation, thus reducing the cell's volumetric energy density and causing current to concentrate near the bare cell 10 during use, accelerating the aging of the tab adhesive 121, and impacting cell usability and increasing manufacturing costs, this embodiment replaces the traditional external tabs with multi-layer foil sheets 12. Multiple foil sheets 12 are connected to their respective corresponding foil tabs 1000. During connection, since the foil tabs 1000 and foil sheets 12 are connected one-to-one, and the foil sheets 12 are relatively thinner than traditional external tabs, the heat-affected zone is relatively small. This reduces the length of the welding area along the electrode sheet 100, thereby reducing the volumetric space occupied within the cell. Meanwhile, the introduction of foil 12 can expand the conductive area, disperse the current density, reduce the generation of hot spots, and solve the problem that when the battery cell is in use, the current tends to concentrate near the bare battery cell 10 at the foil tab 1000, which accelerates the aging of the tab adhesive 121 and affects the use of the battery cell, thus improving the battery's service life.

[0034] In the above embodiments, foil 12 refers to a thin sheet made of pure metal, which can be selected according to actual needs. For example, foil 12 can be aluminum foil or copper foil.

[0035] Please see Figures 1 to 5 In one embodiment, adjacent foils 12 are hot-pressed together by an adhesive layer 122.

[0036] It should be noted that adjacent foils 12 are connected by hot melt adhesive. Compared with complex mechanical connection methods, hot melt adhesive connection is simpler, reduces manufacturing costs and the complexity of the production process, and achieves a simple and effective connection structure. Therefore, in this embodiment, multiple adjacent foils 12 are preferably hot-pressed together by adhesive layer 122 to form tab assembly 120. Specifically, adhesive layer 122 can be naphthenic rubber, hydrogenated petroleum resin, SEBS rubber (Styrene Ethylene Butylene Styrene: hydrogenated styrene-butadiene block copolymer), etc.

[0037] In the above embodiments, the adhesive layers 122 between multiple foils 12 are connected by fusion welding. Fusion welding is a method of melting and bonding two objects together by heating. By heating the adhesive layers 122, they melt and form a connection, thereby connecting the adhesive layers 122 between multiple foils 12. Through fusion welding, a strong connection can be formed between the adhesive layers 122. Compared with traditional laser welding, the equipment used for fusion welding is cheaper, thereby reducing manufacturing costs. Due to the high temperature and melting state during the fusion welding process, the adhesive layers 122 can be better bonded together, resulting in a more uniform connection. This helps ensure a uniform distribution of stress and pressure inside the battery, reduces stress concentration between battery components, strengthens the sealing of the connection between the foils 12, and improves the battery's durability and reliability. Furthermore, through fusion welding, a dense connection is formed between the adhesive layers 122, allowing current to be conducted more smoothly, reducing resistance loss at the connection point, improving the battery's energy conversion efficiency, and enhancing the battery's safety performance.

[0038] Furthermore, in one embodiment, the thickness of the adhesive layer 122 ranges from 1 to 20 micrometers. It is understood that an excessively thick adhesive layer 122 can easily lead to increased contact resistance between the foil tabs 1000, affecting the charging and discharging efficiency of the battery cell; an excessively thin adhesive layer 122 will result in unevenness, leading to insufficient local conductivity. Therefore, in this embodiment, the adhesive layer 122 disposed between the foil tabs 1000 is in the range of 1 to 20 micrometers, which is beneficial for ensuring the continuity of the conductive path. Specifically, in this embodiment, the adhesive layer 122 can be a conductive hot melt adhesive. For example, adding silver powder to the hot melt adhesive can both ensure the continuity of the conductive path and avoid introducing too much insulating substrate due to an excessively thick adhesive layer 122.

[0039] It should be noted that after the bare cell 10 is encapsulated inside the aluminum-plastic film assembly 11, the second connection area 124 between adjacent foils 12 can also be ultrasonically welded together after extending out of the aluminum-plastic film.

[0040] Please see Figures 1 to 5 In one embodiment, a first connecting area 123 and a second connecting area 124 are further provided on the large surface of the foil 12, and the adhesive layer 122 is disposed between the first connecting area 123 and the second connecting area 124. The foil 12 is connected to the foil tab 1000 through the first connecting area 123.

[0041] In this embodiment, the first connection area 123 is used to connect the foil tabs 1000. Specifically, the connection can be made using ultrasonic welding, electromagnetic pulse welding, or laser welding; this embodiment is not limited in this regard. The second connection area 124 is used to connect to an external circuit. It should be noted that, in order to minimize the space occupied by the welding area within the battery cell, the size of the first welding area is determined based on the size of the foil tabs 1000. The second connection area 124 is used for connections between adjacent foils 12 and for connections to external circuits. Specifically, the bare battery cell 10 is encapsulated within an aluminum-plastic film, and the second connection area 124 extends out of the aluminum-plastic film. When the second connection area 124 is connected to an external circuit, multiple layers of the second connection area 124 and the external circuit can be welded together using ultrasonic welding, electromagnetic pulse welding, or laser welding.

[0042] Please see Figures 1 to 5 In one embodiment, the encapsulation edge 1100 of the aluminum-plastic film assembly 11 is heat-sealed with the tab assembly 120 by an adhesive layer 122.

[0043] In this embodiment, an adhesive layer 122 is provided on the large surface of the foil 12. This adhesive layer 122 can be provided on one side of the foil 12 or on both sides of the foil 12. Specifically, since the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120 need to be hot-pressed and fused to the aluminum-plastic film assembly 11 via the adhesive layer 122, an adhesive layer 122 can be provided on the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120. In the actual manufacturing process of the soft-pack battery structure 1, to reduce unnecessary steps, in this embodiment, an adhesive layer 122 is uniformly provided on both large surfaces of the foil 12, and the thickness of the adhesive layer 122 covering the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120 is greater than the thickness of the adhesive layer between foils 12.

[0044] It should be noted that, in the traditional case, the aluminum-plastic film assembly 11 is connected to the outer tab by heat-melting the tab adhesive 121 on the outer tab. Specifically, the tab adhesive 121 is a gel-like substance, typically comprising a multi-layer structure, including a core layer, an upper surface layer, and a lower surface layer. The core layer is an insulating layer, while the upper and lower surface layers are heat-sealing layers. The upper and lower surface layers can fill the space between the tab assembly 120 and the aluminum-plastic film assembly 11, forming a sealed connection. This sealed connection effectively prevents gas or liquid from penetrating into the battery, improving connection stability. Because the tab adhesive 121 provides good sealing, it helps reduce oxidation and leakage within the battery, lowering internal resistance and improving energy conversion efficiency and power output. Furthermore, after melting, the tab adhesive 121 can also fill the space between the foil 12 and the adhesive layer 122, acting as a buffer to reduce electrode vibration and deformation, decrease stress concentration in the electrode material, and extend battery life. In one embodiment, the encapsulation edge 1100 of the aluminum-plastic film assembly 11 is heat-sealed with the tab assembly 120 by tab adhesive 121.

[0045] In the above embodiments, since the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120 need to be hot-pressed to the aluminum-plastic film assembly 11 via tab adhesive 121, tab adhesive 121 can also be provided on the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120. Specifically, in the actual manufacturing process, only tab adhesive 121 can be provided on the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120, or an adhesive layer 122 can be provided on the outer sides of the uppermost and lowermost foils 12 of the tab assembly 120, and then tab adhesive 121 can be provided on the adhesive layer 122.

[0046] It is understandable that, since the tab adhesive 121 is usually a multi-layered structure, the manufacturing process is relatively complex, and more material components are used. For example, in the tab adhesive 121, the insulating material of the core layer is usually modified polypropylene, while the upper and lower surface layers are made of cast polypropylene. Therefore, the market price of the tab adhesive 121 is higher than that of the adhesive layer 122. In order to reduce the cost of materials, the cost of the battery is relatively high. In the embodiments provided in this application, the encapsulation edge 1100 of the aluminum-plastic film assembly 11 and the tab assembly 120 are preferably heat-sealed by the adhesive layer 122.

[0047] Please see Figures 1 to 5 In one embodiment, the length of the foil tab 1000 along the length direction of the electrode 100 ranges from 1 to 4 millimeters.

[0048] In this embodiment, multiple foil sheets 12 and corresponding foil tabs 1000 are connected by ultrasonic welding. Compared with the laser welding method used in the prior art, the heat-affected zone is relatively small. In the welding area, the length range of the tab along the length direction of the electrode sheet 100 can be reduced from 8 to 10 mm to 1 to 4 mm, thereby reducing the proportion of the welding area.

[0049] Please see Figures 1 to 5 In one embodiment, the aluminum-plastic film assembly 11 includes an upper aluminum-plastic film 110 and a lower aluminum-plastic film 111. Both the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111 are connected to the portion of the foil 12 where the adhesive layer 122 is provided, thus wrapping the bare battery cell 10 inside.

[0050] In this embodiment, the aluminum-plastic film assembly 11 includes an upper aluminum-plastic film 110 and a lower aluminum-plastic film 111. The upper and lower aluminum-plastic films 110 and 111 are used to wrap the bare battery cell 10, forming a complete protective layer. The bonding at the tab adhesive 121 ensures a strong connection between the aluminum-plastic film and the bare battery cell 10, effectively preventing external substances from entering the battery and protecting the bare battery cell 10 from damage. By coating the foil 12 with adhesive layer 122 and bonding it to the aluminum-plastic film, a stable connection of the battery structure is achieved, ensuring a tight bond between the foil 12 and the aluminum-plastic film, improving the overall strength and stability of the battery. The use of the upper and lower aluminum-plastic films 110 and 111 effectively wraps the bare battery cell 10, forming a sealed protective layer to prevent external substances (such as moisture and oxygen) from entering the battery, reducing the risk of the battery's internal components being affected by the external environment, and improving the battery's reliability and safety.

[0051] Please see Figures 1 to 5 In one embodiment, both the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111 are provided with grooves 1111 that match the bare battery cell 10, and the grooves 1111 are used to accommodate the bare battery cell 10.

[0052] In this embodiment, the aluminum-plastic film assembly 11 connects to the bare battery cell 10 by providing a groove 1111. Specifically, the surface of the aluminum-plastic film assembly 11 is provided with a groove 1111, the shape and size of which match the bare battery cell 10, so that the bare battery cell 10 can be placed in the groove 1111. By placing the bare battery cell 10 in the groove 1111 of the aluminum-plastic film assembly 11, the connection process can be completed quickly without complicated instruments or tools. The design of the groove 1111 allows the bare battery cell 10 to be firmly embedded therein, thereby achieving a stable and reliable connection. The high fit between the groove 1111 and the bare battery cell 10 forms a large contact area, increasing the stability of the connection. This structural connection method can effectively resist the interference of external forces and vibrations, improve the reliability of the connection, and the structural connection between the groove 1111 and the bare battery cell 10 has excellent sealing performance. Through the design of the groove 1111, a sealing effect can be achieved, preventing external moisture, dust and other substances from entering the connection components and protecting the battery cell from damage. Especially in harsh environments, this high sealing performance is very beneficial. Compared with other complex connection methods, the aluminum-plastic film assembly 11 has a relatively simple design and requires less material, thereby reducing manufacturing costs.

[0053] Please see Figures 1 to 5 In one embodiment, the opening edge of the groove 1111 of the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111 extends away from the groove 1111 to form the encapsulation edge 1100 of the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111.

[0054] In this embodiment, the structural connection between the groove 1111 and the foil 12 is achieved by bonding the encapsulation edges 1100 of the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111 to the tab adhesive 121 or adhesive layer 122. Specifically, the opening edges of the grooves 1111 of the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111 extend away from the side of the grooves 1111, forming the encapsulation edges 1100 of the upper aluminum-plastic film 110 and the lower aluminum-plastic film 111. Then, the encapsulation edges 1100 are firmly bonded to the foil 12 by adhesive to form the encapsulation edges 1100 of the aluminum-plastic film assembly. By using adhesive bonding, a high connection strength can be achieved. The adhesive possesses excellent bonding properties, firmly bonding the encapsulation edges 1100 of the upper and lower aluminum-plastic films 110 and 111 to the foil 12, ensuring the stability and reliability of the connection. It effectively prevents malfunctions and safety hazards caused by loose connections during battery use. A strong connection reduces the risk of loose internal solder joints, avoiding short circuits or other safety issues. Compared to traditional welding methods, adhesive bonding simplifies the encapsulation process. It eliminates the need for high-temperature welding and additional connecting materials, reducing production steps and equipment costs, improving production efficiency, and providing lower internal resistance and better current conduction performance, thereby enhancing battery discharge performance and cycle life. Furthermore, adhesive bonding effectively reduces contact resistance at connection points, improving overall battery performance and energy efficiency.

[0055] In one embodiment, a fireproof layer is provided in the groove 1111.

[0056] In this embodiment, the plastic film assembly not only accommodates the bare battery cell 10 but also includes a fireproof layer. This fireproof layer is disposed within the aluminum-plastic film groove 1111 to provide additional fire protection. The presence of the fireproof layer provides excellent fire resistance for the bare battery cell 10. During use, the bare battery cell 10 may face unexpected situations such as overcharging or short circuits, which could lead to overheating, combustion, or even explosion. The fireproof layer effectively isolates the battery cell from the external environment, preventing the spread of flames and thus reducing the risk of fire and protecting user safety. Furthermore, the fireproof layer can also reduce damage to the bare battery cell 10 when subjected to mechanical compression or external impact.

[0057] Specifically, the fireproof layer can be a fire-retardant coating or a composite flame-retardant material, such as adding a flame retardant to the adhesive layer of the aluminum-plastic film. In actual preparation, a roll forming process can be used to calender and laminate the fire-retardant coating layer with the aluminum-plastic film.

[0058] To more clearly illustrate the specific implementation of the pouch battery structure 11 in the embodiments of this application, this application also provides a fabrication process for the pouch battery structure 1, the specific steps of which are as follows:

[0059] S1. Positive electrode roll and negative electrode roll are prepared by coating positive electrode slurry and negative electrode slurry;

[0060] S2. Bake the above positive electrode roll and negative electrode roll, and then roll them.

[0061] S3. Connect the positive electrode roll and the negative electrode roll to the corresponding foil 12 respectively;

[0062] S4. Cut the positive electrode roll and negative electrode roll after welding foil 12 into slices to obtain positive electrode sheet and negative electrode sheet respectively.

[0063] S5. Stack the positive electrode and the negative electrode in sequence to obtain the bare cell 10, and set a separator between the positive electrode and the negative electrode.

[0064] S6. The bare cell 10 is encapsulated in the aluminum-plastic film assembly 11 to obtain the soft-pack battery structure 1.

[0065] Please see Figure 4 and Figure 5 In step S3, adhesive layers 122 are provided on both sides of the foil 12, and the adhesive layers 122 are provided between the first connection area 123 and the second welding area 124. The electrode roll includes a coating area and a reserved foil tab 1000. The first connection area 123 of one foil 12 and the foil tab 1000 of the positive electrode roll are welded together by ultrasonic welding, and the first connection area 123 of another foil 12 and the foil tab 1000 of the negative electrode roll are welded together by ultrasonic welding.

[0066] It should be noted that in step S3, the connection method between the foil 12 and the electrode roll can also be as follows: the first connection area 123 of one foil 12 and the foil tab 1000 of the positive electrode roll are welded together by resistance welding, and the first connection area 123 of another foil 12 and the foil tab 1000 of the negative electrode roll are welded together by resistance welding. Alternatively, the connection method between the foil 12 and the electrode roll can be as follows: the first connection area 123 of one foil 12 and the foil tab 1000 of the positive electrode roll are welded together by ultrasonic welding, and the first connection area 123 of another foil 12 and the foil tab 1000 of the negative electrode roll are welded together by resistance welding; or the first connection area 123 of one foil 12 and the foil tab 1000 of the positive electrode roll are welded together by resistance welding, and the first connection area 123 of another foil 12 and the foil tab 1000 of the negative electrode roll are welded together by ultrasonic welding. Resistance welding, also known as spot welding, involves applying pressure through electrodes and using the resistance heat generated by electric current to melt overlapping metal workpieces at local contact points and form weld points.

[0067] In step S5, the positive electrode and the negative electrode are stacked in sequence, and the corresponding foils 12 are also stacked together, and the adhesive between adjacent foils 12 is stacked together.

[0068] It should be noted that, in manufacturing bare cells, this application preferably uses the above-mentioned process of stacking positive and negative electrode sheets, but the use of the above-mentioned stacking process should not be a limitation of this application in manufacturing bare cells. For example, positive electrode sheets, negative electrode sheets, and separators can also be prepared into bare cells by winding, with the adhesive between adjacent foils 12 being stacked together.

[0069] In step S6, encapsulating the bare cell 10 in the aluminum-plastic film assembly 11 includes placing the bare cell 10 in the groove 1111 of the lower aluminum-plastic film 111, applying sealant to the encapsulation edge of the lower aluminum-plastic film 111, aligning the groove 1111 of the upper aluminum-plastic film 110 with the groove 1111 of the lower aluminum-plastic film 111, and covering them together. The foil 12 abuts against the encapsulation edge of the lower aluminum-plastic film 111 and the encapsulation edge of the lower aluminum-plastic film 111 through the adhesive layer 122. Finally, the adhesive layer 122 is melted by hot pressing to seal the bare cell 10 in the aluminum-plastic film assembly 11. Finally, the encapsulation edge coated with sealant is wound to form a rolled edge, resulting in the soft-pack battery structure 1.

[0070] It should be noted that in the traditional soft-pack battery structure 1, after the positive and negative electrode sheets are stacked, they need to be connected to the outer tabs by laser or ultrasonic welding. The outer tabs are usually provided with tab adhesive 121 on both sides. Since the outer tabs are relatively thick and need to be welded to the multi-layer foil tabs 1000, the required welding energy is relatively large, the heat-affected zone is large, and the outer tabs are usually copper or aluminum sheets that can conduct heat, which can affect the tab adhesive 121 to a certain extent, melting part of the tab adhesive 121, thereby reducing the subsequent aluminum-plastic film encapsulation effect and easily leading to battery leakage. The above-mentioned preparation process provided in this application has a lower welding energy required because the foil material is thinner than the outer electrode in step S3, and the foil electrode 1000 is a single-layer structure. The welding energy required to connect the foil sheet 12 to the single-layer foil electrode 1000 is much lower than that required to weld the outer electrode to the multi-layer foil electrode 1000 in the transmission process. Therefore, the impact on the adhesive layer 122 is lower. After the foil sheet 12 and the single-layer foil electrode 1000 are ultrasonically welded, it does not have a significant impact on the adhesive layer 122 on the foil, and is not enough to melt the adhesive layer 122. Therefore, compared with the traditional preparation process, it can improve the packaging effect of the aluminum-plastic film.

[0071] Furthermore, the adhesive layer 122 used in this application embodiment has a relatively lower cost compared to the tab adhesive 121. In the above process, the aluminum-plastic film is encapsulated using the adhesive layer 122, which reduces the manufacturing cost of the soft-pack battery structure 1.

[0072] It should be noted that before step S6, the second welding area 124 of the multilayer foil 12 is pressed together to reduce the gap at the interface between adjacent foils 12, thereby reducing the contact resistance. Simultaneously, if a multilayer adhesive tab 121 is used for thermoforming, delamination can easily occur due to differences in the coefficients of thermal expansion during electrolyte immersion or thermal cycling. By pressing the second welding area 124 of the multilayer foil 12 together, the interface peeling between the adhesive tab 121 and the foil can be suppressed, preventing leakage at the encapsulation point.

[0073] In summary, a soft-pack battery structure 1 according to an embodiment of this application includes a bare cell 10, wherein the bare cell 10 includes a plurality of electrode sheets 100, and the portions of the electrode sheets 100 extending out of the bare cell 10 are foil tabs 1000; a tab assembly 120 includes a plurality of stacked foil sheets 12, wherein the plurality of foil sheets 12 are respectively connected to their respective corresponding foil tabs 1000; and an aluminum-plastic film assembly 11 for accommodating the bare cell 10, wherein the aluminum-plastic film assembly 11 includes an encapsulation edge 1100, the encapsulation edge 1100 is connected to the foil sheet 12 near one end of the bare cell 10, and the tab assembly 120 extends out of the encapsulation edge 1100 for electrical connection with the outside. This technical solution replaces the connection between the outer electrode tab and the foil electrode tab 1000 with the foil sheet 12. That is, the connection between the multi-layer foil electrode tab 1000 and a single outer electrode tab is changed to a one-to-one connection between the foil electrode tab 1000 and the foil sheet 12. Since the thickness of the foil sheet 12 is thinner than that of the outer electrode tab, the welding energy required when welding a single foil sheet 12 to a single foil electrode tab 1000 is relatively small, and its hot melt area is relatively small. Therefore, it can reduce the welding area when welding the foil electrode tab 1000 to the foil sheet 12, reduce the volume occupied by this area inside the cell, and improve the volumetric energy density of the cell.

[0074] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A soft-pack battery structure, characterized in that, include: A bare battery cell, comprising multiple electrode plates, wherein the portion of the electrode plate extending out of the bare battery cell is a foil tab; The electrode assembly includes multiple stacked foils, each of which is connected to its corresponding foil electrode. An aluminum-plastic film assembly is used to house the bare battery cell. The aluminum-plastic film assembly includes an encapsulation edge connected to a foil sheet near one end of the bare battery cell. The tab assembly extends out of the encapsulation edge for electrical connection to an external source.

2. The soft-pack battery structure according to claim 1, characterized in that, The adjacent foils are hot-pressed together by an adhesive layer.

3. The soft-pack battery structure according to claim 2, characterized in that, The thickness of the adhesive layer ranges from 1 to 20 micrometers.

4. The soft-pack battery structure according to claim 2, characterized in that, The foil sheet also has a first connection area and a second connection area on its large surface. The adhesive layer is disposed between the first connection area and the second connection area. The foil sheet is connected to the foil tab through the first connection area.

5. The soft-pack battery structure according to claim 2, characterized in that, The encapsulation edge of the aluminum-plastic film assembly is sealed to the tab assembly by heat fusion with an adhesive layer.

6. The soft-pack battery structure according to claim 4, characterized in that, The length of the foil tab along the length direction of the electrode sheet ranges from 1 to 4 millimeters.

7. The soft-pack battery structure according to claim 5, characterized in that, The aluminum-plastic film assembly includes an upper aluminum-plastic film and a lower aluminum-plastic film. Both the upper and lower aluminum-plastic films are connected to the part of the tab assembly where the adhesive layer is provided, thus wrapping the bare battery cell inside.

8. The soft-pack battery structure according to claim 7, characterized in that, Both the upper and lower aluminum-plastic films are provided with grooves that match the bare battery cells, and the grooves are used to accommodate the bare battery cells.

9. The soft-pack battery structure according to claim 8, characterized in that, The opening edges of the grooves in the upper and lower aluminum-plastic films extend away from the side of the grooves to form the encapsulation edges of the upper and lower aluminum-plastic films.

10. The soft-pack battery structure according to claim 8, characterized in that, A fireproof layer is provided inside the groove.

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