Composite cover plate, soft package battery and preparation method of soft package battery

Abstract

The invention provides a composite cover plate, a soft package battery and a preparation method thereof, and relates to the technical field of new energy batteries. Wherein the composite cover plate comprises a cover plate main body and a pole lug, the pole lug is arranged in the circumferential direction of the cover plate main body, the outer edge of the pole lug is provided with a folding edge perpendicular to the cover plate main body, the folding edge is used for being connected with a soft package material in a sealing manner, the cover plate main body is provided with a pole column, and the pole column is used for being connected with an electrode end of a battery cell. According to the composite cover plate, the soft package battery and the preparation method of the composite cover plate, the pole is arranged in the middle of the cover plate main body, the tabs are arranged in the circumferential direction of the cover plate main body, the overcurrent capacity of the battery is improved by means of the large sectional area of the pole, and the folded edge is perpendicular to the cover plate main body, so that sealing with an aluminum-plastic film wound in the circumferential direction of a battery cell is facilitated; therefore, the packaging of the battery cell is realized by means of the cover plate and the soft package material, a space is expanded for increasing the thickness of the soft package battery, and the capacity of the battery is favorably improved.

Description

Technical Field

[0001] This invention relates to the field of new energy battery technology, and in particular to a composite cover plate, a soft-pack battery, and a method for preparing the same. Background Technology

[0002] A major direction in lithium-ion battery development is to improve energy density to extend the driving range of electric vehicles. Energy density includes gravimetric energy density and volumetric energy density. Pouch batteries use a thin aluminum-plastic film as the pouch material, which helps reduce the weight of auxiliary materials within the battery structure, resulting in a generally higher gravimetric energy density. The aluminum-plastic film pouch material has a three-layer structure: the outermost layer is a nylon / polyethylene terephthalate (PET) layer, used to prevent oxygen penetration from the air, maintain the internal environment of the cell, and provide external protection; the middle layer is an aluminum layer, which, relying on the natural advantages of metallic bonds, isolates moisture and oxygen from the cell, preventing them from reacting with the electrolyte and generating large amounts of gas that could cause battery expansion; the innermost layer is a cast polypropylene (CPP) layer, which has good heat-sealing properties and mainly serves as a heat-melt encapsulation layer.

[0003] Soft-pack batteries use thin-film tabs as a current conduction method, resulting in lighter weight and better mass energy density compared to aluminum-cased batteries. However, the aluminum-plastic film used for encapsulation in soft-pack batteries has a limited depth, making it difficult for the thickness of the soft-pack cell to exceed 15mm, thus limiting battery capacity. Furthermore, the thin tabs in soft-pack batteries, limited by the density of the battery itself, result in a smaller cross-sectional area, leading to significant heat generation during high-current charging and discharging, potentially causing battery damage or shortening cycle life. Summary of the Invention

[0004] This invention provides a composite cover plate, a soft-pack battery, and a method for preparing the same, in order to solve the defects of existing soft-pack batteries, which use thin sheet-like tabs, have small cross-sectional areas, low current carrying capacity, and have battery capacity limited by aluminum-plastic film.

[0005] In a first aspect, embodiments of the present invention provide a composite cover plate, including a cover plate body and an electrode tab, wherein the electrode tab is arranged circumferentially around the cover plate body, wherein the outer edge of the electrode tab has a folded edge perpendicular to the cover plate body, the folded edge is used for sealing connection with a soft-pack material, and the cover plate body is provided with an electrode post, the electrode post is used for connecting to the electrode terminals of a battery cell.

[0006] According to an embodiment of the present invention, a composite cover plate is provided in which the electrode tab and the cover plate body are integrally formed.

[0007] According to an embodiment of the present invention, a composite cover plate is provided in which the electrode lug is welded and fixed to the cover plate body.

[0008] According to an embodiment of the present invention, a composite cover plate is provided, wherein the pole post and the cover plate body are an integral structure.

[0009] According to an embodiment of the present invention, a composite cover plate is provided, wherein the cover plate body is provided with a pole hole, and the pole is installed in the pole hole.

[0010] According to an embodiment of the present invention, a composite cover plate is provided, wherein there are two poles, one of which is a positive pole and the other is a negative pole.

[0011] According to an embodiment of the present invention, a composite cover plate is provided with tab adhesive on the outer side of the folded edge.

[0012] According to an embodiment of the present invention, a composite cover plate is provided, wherein the inner side of the folded edge is provided with the tab adhesive.

[0013] According to an embodiment of the present invention, a composite cover plate is provided, wherein the electrode lug includes a base plate, a folded edge, and a connecting edge. The base plate is parallel to the cover plate body, the folded edge and the connecting edge are perpendicularly disposed on opposite sides of the base plate, and the connecting edge is connected to the cover plate body.

[0014] Secondly, embodiments of the present invention also provide a soft-pack battery, which includes a battery cell and a composite cover plate as described in the first aspect, wherein the positive and negative electrodes of the battery cell are respectively connected to the terminals of the composite cover plate.

[0015] Thirdly, embodiments of the present invention also provide a method for preparing a pouch cell, comprising:

[0016] The positive and negative terminals of the battery cell are welded and fixed to the terminals of the composite cover plate, respectively.

[0017] The battery cell and the composite cover are covered with a soft-pack material, with an air pocket provided; the soft-pack material is pre-sealed at both ends near the battery cell.

[0018] The tabs are sealed to the soft packaging material by hot pressing.

[0019] According to the method for preparing a soft-pack battery provided in the embodiments of the present invention, the step of welding and fixing the positive and negative terminals of the battery cell to the terminals of the composite cover plate specifically includes:

[0020] The current collector of the battery cell is bent at 90°, and the bent current collector is welded and fixed to the flexible connecting piece. Then the flexible connecting piece is welded and fixed to the pole of the composite cover plate.

[0021] According to the method for preparing a soft-pack battery provided in the embodiments of the present invention, the step of sealing the tab to the soft-pack material by hot pressing specifically includes:

[0022] The tabs and the soft-pack material are rolled and heat-pressed together using aligned cylindrical or segmented end caps.

[0023] Alternatively, inner and outer straight end caps or inner and outer circular arc end caps can be used to splice and encapsulate the electrode tabs and the soft packaging material.

[0024] According to the method for preparing a soft-pack battery provided in the embodiments of the present invention, after sealing the tabs to the soft-pack material by hot pressing, the method further includes:

[0025] Top sealing operations are performed on the positive and negative sides of the battery cell, and the positive and negative terminals of the air bag are sealed respectively.

[0026] Electrolyte is injected into the battery cell, and the side of the gas bag is sealed after the injection is completed; the battery cell is subjected to formation treatment, and after the formation of the battery cell is completed, the gas is vented and sealed again.

[0027] The composite cover plate, soft-pack battery, and preparation method provided by the present invention have an electrode post in the middle of the cover plate body and electrode tabs arranged around the circumference of the cover plate body. The large cross-sectional area of ​​the electrode post improves the current carrying capacity of the battery. The folded edge is perpendicular to the cover plate body, which facilitates sealing with the aluminum-plastic film around the circumference of the battery cell. This allows the battery cell to be encapsulated by the cover plate and soft-pack material, opening up space for increasing the thickness of the soft-pack battery and helping to increase the battery capacity. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a cross-sectional view of the composite cover plate provided in an embodiment of the present invention;

[0030] Figure 2 This is a cross-sectional view of a composite cover plate provided in another embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the fit between the battery cell and the composite cover plate provided in an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the structure of the soft-pack battery after side sealing pre-sealing according to an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of the structure of the soft-pack battery after the tabs are packaged, according to an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the structure of the soft-pack battery after top sealing according to an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the structure of the soft-pack battery after vacuuming and double sealing according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the structure of the soft-pack battery after folding, as provided in an embodiment of the present invention.

[0037] Figure label:

[0038] 210. Composite cover plate; 211. Cover plate body; 212. Electrode lug; 213. Electrode post; 214. Electrode lug adhesive; 215. Folded edge; 216. Connecting edge; 100. Battery cell; 111. Current collector welding end; 300. Aluminum-plastic film; 301. Air bag; 311. Positive electrode side seal pre-sealing edge; 312. Negative electrode side seal pre-sealing edge; 321. Positive electrode top seal edge; 322. Negative electrode top seal edge; 331. Positive electrode air bag seal edge; 332. Negative electrode air bag seal edge; 340. Vacuum double seal edge; 341. Sealing folded edge; 400. Flexible connecting piece; 501. Outer end cap; 502. Inner end cap. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0041] In the description of this invention, 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," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] The following is combined with Figures 1-2 The composite cover plate of the present invention is described.

[0044] Figure 1 and Figure 2 This is a cross-sectional view of the composite cover plate provided in an embodiment of the present invention, with the cross-sectional line along the length or width direction of the composite cover plate. The composite cover plate 210 provided in this embodiment of the present invention includes a cover plate body 211 and electrode tabs 212, the electrode tabs 212 being arranged circumferentially around the cover plate body 211. A pole post 213 is provided on the cover plate body 211, the pole post 213 being used to connect to the electrode terminals of the battery cell 100. The outer edge of the electrode tab 212 has a flange 215 perpendicular to the cover plate body 211, the flange 215 being used for a sealed connection with the soft-pack material.

[0045] like Figure 1As shown, the cover plate body 211 is a flat metal plate. A terminal post 213 is provided in the middle of the cover plate body 211 for connection to the current collector welding end 111 of the battery cell 100. It is understood that the position of the terminal post 213 can also be set on the side closer to the cover plate body 211 according to the specific structure of the battery cell 100; this embodiment of the invention does not specifically limit the setting position of the terminal post 213. Since the positive and negative terminals of the battery cell 100 can be located at the same end or different ends of the core, the cover plate body 211 can have only one terminal post 213 or two terminal posts 213 to adapt to different types of battery cells 100. When the positive and negative terminals of the battery cell 100 are located at different ends of the core, only one terminal post 213 is provided on the composite cover plate 210. During assembly, composite cover plates 210 are respectively provided at the positive and negative terminals of the battery cell 100, with one composite cover plate 210 serving as the positive terminal cover plate and the other composite cover plate 210 serving as the negative terminal cover plate. The terminal 213 in the positive electrode cover is connected to the positive terminal of the cell 100, and the terminal 213 in the negative electrode cover is connected to the negative terminal of the cell 100. With the positive and negative terminals of the cell 100 located at the same end of the cell body, the composite cover 210 has two terminals 213, one serving as the negative terminal and the other as the positive terminal. During assembly, only one composite cover 210 needs to be installed on the cell 100. Thus, the terminals 213 enable the internal and external connection of the pouch battery, drawing electricity to form a circuit. The cross-sectional area of ​​the terminals 213 is larger than that of the thin tabs in traditional pouch batteries, significantly improving the battery's overcurrent capacity.

[0046] The outer edge of the tab 212 refers to the side of the tab 212 away from the center of the cover body 211. When the tab 212 is arranged around the circumference of the cover body 211, the folded edge 215 forms a side edge in the circumference of the cover body 211 so as to connect with the soft packaging material to achieve a seal.

[0047] Among them, the soft-pack battery uses air bag liquid injection, so the composite cover plate 210 does not need to be equipped with liquid injection hole and explosion-proof valve compared with the cover plate of traditional aluminum shell battery.

[0048] During encapsulation, a composite cover plate 210 is installed on the electrode of the cell 100, and a soft-pack material such as an aluminum-plastic film 300 is wrapped around the circumference of the cell 100, so that the aluminum-plastic film 300 is in contact with the folded edge 215, and then the encapsulation operation is carried out. Finally, the soft-pack material and the composite cover plate 210 are used to achieve sealing compatibility, breaking the technical barrier of sealing between traditional aluminum-cased batteries and soft-pack batteries, opening up space for increasing the thickness of soft-pack batteries, and helping to increase the upper limit of capacity and volumetric energy density of soft-pack batteries.

[0049] The composite cover plate 210 provided in this embodiment of the invention has a terminal post 213 in the middle of the cover plate body 211, and a tab 212 is arranged around the circumference of the cover plate body 211. The large cross-sectional area of ​​the terminal post 213 improves the current carrying capacity of the battery. The folded edge 215 on the tab 212 is perpendicular to the cover plate body 211, which facilitates sealing with the aluminum-plastic film around the circumference of the battery cell. This allows the battery cell to be encapsulated with the cover plate and the soft-pack material, opening up space for increasing the thickness of the soft-pack battery and helping to increase the battery capacity.

[0050] In one optional embodiment, the tab 212 and the cover plate body 211 are an integral structure. Specifically, the opposite ends of the cover plate body 211 are bent towards the welding end of the pole post 213 to form the tab 212, which is simple and easy to manufacture. In yet another optional embodiment, the tab 212 is welded to the cover plate body 211. Specifically, the tab 212 and the cover plate body 211 are separate structures, and the inner edge of the tab 212 is fixed to the cover plate body 211 by laser welding. The inner edge of the tab 212 refers to the side edge of the tab 212 closest to the pole post 213.

[0051] The terminal 213 is used to output the internal electrical energy of the battery cell 100, serving as a conductive connection. Optionally, the terminal 213 and the cover plate body 211 are an integral structure; or, the terminal 213 and the cover plate body 211 are separate, with terminal holes provided on the cover plate body 211, and the terminal 213 installed in the terminal holes. In the case where the terminal 213 and the cover plate body 211 are separate, the assembly of the terminal 213 and the cover plate body 211 can adopt the assembly method of the terminal and cover plate in aluminum-cased batteries.

[0052] like Figure 1 As shown, the cover plate body 211 has only one pole post 213. During manufacturing, the pole post 213 can be constructed on the cover plate body 211 in a one-piece molding manner, or it can be installed separately on the cover plate body 211. For example... Figure 2 As shown, the cover plate body 211 is provided with two pole posts 213, one of which serves as the negative pole post and the other as the positive pole post. During manufacturing, the cover plate body 211 and the pole posts 213 are separately arranged and then assembled on the same cover plate body 211.

[0053] The outer side of the folded edge 215 is provided with tab adhesive 214. The outer side of the folded edge 215 refers to the wall surface of the folded edge 215 facing the outside of the battery cell after the composite cover plate 210 is installed on the battery cell 100. The inner side of the folded edge 215 is opposite to the outer side of the folded edge 215 and belongs to the opposite side of the folded edge 215.

[0054] The tab adhesive 214 covers the outer surface of the folded edge 215 or only a portion of the folded edge 215. For example, the tab adhesive may be applied only to the area near the end of the outer surface of the folded edge 215. The coverage area of ​​the tab adhesive 214 is determined according to the requirements of the heat-pressed packaging width of the flexible packaging material and the tab 212.

[0055] Optionally, the tab adhesive 214 can be any of white adhesive, black adhesive, yellow adhesive, or a single-layer adhesive. White adhesive is made by co-extrusion of three layers of polypropylene material with different functions. The heat-sealing temperature of the functional layers of white adhesive is 150°C–180°C, a relatively wide range, slightly lower than the battery's encapsulation temperature of 180°C–220°C, effectively preventing cross-sectional short circuits and increasing the operable temperature range during encapsulation. Yellow adhesive has a functional layer with a melting point close to 300°C, making heat sealing easier. The middle functional layer is a non-woven fiber layer, resulting in better interface fusion. The appropriate type of tab adhesive 214 should be selected based on factors such as the adhesion between the tab adhesive 214 and the soft-pack material, the tightness of edge sealing, and the sealing process.

[0056] During encapsulation, the soft packaging material and the tab adhesive 214 on the outer side of the folded edge 215 melt together under hot pressing or hot fusion processes to achieve a sealing effect and realize a sealed adhesive connection.

[0057] Optionally, tab adhesive 214 is also provided on the inner side of the folded edge 215. The sealing width of a pouch battery is usually more than 2mm. Under the same thermo-pressed sealing width target, tab adhesive 214 is provided on both the inner and outer sides of the folded edge 215. Compared with tab adhesive only being provided on the outer side of the folded edge 215, the setting width of tab adhesive on one side can be shortened, and the sealing effect of the pouch material and the tab can be effectively improved.

[0058] During the use of pouch batteries, the tabs 212 are constantly immersed in the electrolyte. With continuous charging and discharging during the application of the pouch battery, the tab adhesive 214 will age under alternating high and low temperature and high voltage environments, affecting its mechanical properties and adhesive performance, thereby reducing the bonding reliability and service life. To address this, this embodiment of the invention provides tab adhesive 214 on both the inner and outer sides of the folded edge 215, thereby increasing the sealing width and improving the reliability and durability of the tabs 212 and the pouch material encapsulation.

[0059] In one specific embodiment, the tab 212 is L-shaped, with its horizontal plate connected to the cover plate body 211 and its vertical plate arranged vertically to form a folded edge 215.

[0060] In yet another specific embodiment, such as Figure 1 As shown, the tab 212 includes a base plate and a connecting edge 216. The base plate is parallel to the cover plate body 211, and the folded edge 215 and the connecting edge 216 are perpendicularly arranged on opposite sides of the base plate. The connecting edge 216 is connected to the cover plate body 211.

[0061] like Figure 1 As shown, the tab 212 is recessed towards the inner connection end of the terminal post 213, forming two vertical edges on the left and right. The vertical edge farther from the terminal post 213 is the folded edge 215, and the vertical edge closer to the terminal post 213 is the connection edge. It should be noted that the inner connection end of the terminal post 213 refers to the end of the terminal post 213 connected to the battery cell 100; the outer connection end of the terminal post 213 is opposite to the inner connection end of the terminal post 213, and it refers to the end of the terminal post 213 farther away from the battery cell 100.

[0062] like Figure 1 As shown, the folded edge 215 and the connecting edge 216 have different lengths, with the folded edge 215 being longer than the connecting edge 216, in order to increase the connection length between the tab 212 and the soft-pack material and improve the connection stability.

[0063] Traditional tabs 212 are flat, thin sheet structures. In the composite cover plate 210 provided in this embodiment of the invention, tabs 212 are three-dimensional structures. When the composite cover plate 210 is fixed to the end of the cell 100, it is used in conjunction with soft-pack material to complete the encapsulation of the cell 100, thereby improving the upper limit of the capacity and the volumetric energy density of the cell 100.

[0064] The following is combined with Figure 3 The present invention describes a pouch cell battery.

[0065] This invention also provides a pouch cell battery, which includes a cell 100 and a composite cover plate 210 as described above. The positive and negative terminals of the cell 100 are respectively connected to the terminals of the composite cover plate 210.

[0066] Among them, cell 100 has the same cell structure as that of a traditional soft-pack battery. The soft-pack battery uses... Figure 1 The composite cover plate shown, Figure 3 This is a schematic diagram illustrating the fit between the battery cell and the composite cover plate provided in an embodiment of the present invention. Figure 3 As shown, a positive terminal is reserved at the top of the battery cell 100, and a negative terminal is reserved at the bottom of the battery cell 100. A composite cover plate 210 serves as the positive terminal cover plate and is installed at the positive terminal connection of the battery cell 100; another composite cover plate 210 serves as the negative terminal cover plate and is installed at the negative terminal connection of the battery cell 100. Specifically, the terminal post 213 of the positive terminal cover plate is connected to the positive terminal connection via a flexible connecting piece 400, and the terminal post 213 of the negative terminal cover plate is connected to the negative terminal connection via another flexible connecting piece 400. The tab 212 of the positive terminal cover plate is heat-pressed with the aluminum-plastic film 300 to form a positive side seal pre-sealing edge 311, and the tab 212 of the negative terminal cover plate is heat-pressed with the aluminum-plastic film 300 to form a negative side seal pre-sealing edge 312.

[0067] Understandably, if a pouch battery uses such... Figure 2As shown in the composite cover plate, the positive and negative terminals of the battery cell 100 are located at the same end. The two terminals 213 on the composite cover plate are connected to the two battery terminals respectively. The specific connection process is similar to that above and will not be repeated.

[0068] Compared to traditional soft-pack batteries that rely entirely on aluminum-plastic film encapsulation, in this soft-pack battery, the terminals of the cell 100 are encapsulated with a composite cover plate 210, and the circumferential direction of the cell 100 is encapsulated with an aluminum-plastic film 300. The composite cover plate 210 provides space for the charging expansion of the cell 100 and the terminal post 213 improves the battery's overcurrent capacity. At the same time, the circumferential encapsulation with the aluminum-plastic film 300 avoids the problem of low energy density in traditional aluminum-cased batteries.

[0069] The following is combined with Figures 3-8 The method for preparing the pouch cell of the present invention is described.

[0070] This invention also provides a method for preparing the soft-pack battery as described above, which includes the following steps:

[0071] Step S10: Weld and fix the positive and negative terminals of the battery cell 100 to the terminal post 213 of the composite cover plate 210, respectively.

[0072] Step S20: Use soft packaging material to cover the battery cell 100 and the composite cover plate 210, and leave an air bag 301; pre-seal the soft packaging material at both ends near the battery cell 100.

[0073] Step S30: The tab 212 is sealed and connected to the soft packaging material by hot pressing.

[0074] Specifically, such as Figure 3 As shown, one end of the battery cell 100 is the positive terminal, and the other end is the negative terminal. The negative terminal current collector is connected to the terminal post 213 of a composite cover plate 210, which serves as the negative terminal lead. Similarly, the positive terminal current collector is connected to the terminal post 213 of another composite cover plate 210, which serves as the positive terminal lead. Alternatively, the positive and negative terminals of the battery cell 100 can be located at the same end, in which case a composite cover plate 210 with two terminals 213 can be used. The cross-sectional area of ​​the terminal post 213 is larger than that of the traditional thin-plate tab 212, which can support a larger charging and discharging current and effectively improve the battery's overcurrent capacity.

[0075] The packaging of a composite cover plate 210 with a single terminal and a cell 100 is similar to the packaging of a composite cover plate 210 with two terminals and a cell 100. The following describes the preparation method of a pouch battery by taking the packaging process of a composite cover plate 210 with a single terminal 213 and a cell 100 as an example.

[0076] Flexible packaging materials, such as aluminum-plastic film 300, are wrapped around the outside of the battery cell 100 and the composite cover plate 210, with an air bag 301 reserved on one side of the battery cell 100. The flexible packaging materials are pre-sealed at both ends near the battery cell 100. Figure 4 This is a schematic diagram of the structure of a soft-pack battery after side sealing pre-sealing, as provided in an embodiment of the present invention. Figure 4 As shown, after side sealing, a positive side sealing pre-sealing edge 311 and a negative side sealing pre-sealing edge 312 are formed on the side of the positive and negative terminals of the flexible packaging material closest to the battery cell. The positive and negative side sealing pre-sealing edges 311 and 312 are used to bond the flexible packaging material to the outer surface of the tab 212 of the composite cover plate 210. The outer surface of the tab 212 is provided with tab adhesive 214, which facilitates hot-pressing for fusion sealing after the flexible packaging material is bonded to the outer surface of the tab 212 of the composite cover plate 210. During hot pressing, the functional layer in the tab adhesive 214 melts and bonds with the encapsulation layer in the flexible packaging material, such as the aluminum-plastic film 300, to form an effective encapsulation structure, achieving tab encapsulation. The encapsulation layer of the aluminum-plastic film 300 refers to the innermost layer of the aluminum-plastic film.

[0077] The pouch battery manufacturing method provided in this embodiment of the invention, compared with the traditional pouch battery manufacturing method, first installs composite cover plates 210 at opposite ends of the cell 100, and then covers the cell 100 with pouch material along the circumference. The pouch material and the composite cover plates 210 jointly seal the cell 100, thereby introducing the outer casing packaging process of aluminum-cased batteries into the pouch battery process, reducing the space occupied by the electrode tab 212 welding area in the traditional pouch battery, improving the volume utilization rate of the cell 100, and thus improving the battery capacity and volumetric energy density.

[0078] Step S10, which involves welding and fixing the positive and negative terminals of the battery cell 100 to the terminal posts 213 of the composite cover plate 210, specifically includes:

[0079] Step S11: Bend the current collector of cell 100 by 90°. Step S12: Weld the bent current collector to the flexible connector 400 for fixation. Step S13: Weld the flexible connector 400 to the terminal post 213 of composite cover plate 210 for fixation.

[0080] When installing the composite cover plate 210 at the negative terminal of the battery cell 100, the negative current collector of the battery cell 100 is bent at 90°, and then the flexible connecting piece 400 is welded to the welding end of the negative current collector. Then, the flexible connecting piece 400 is welded to the terminal post 213 of the composite cover plate 210. The method of installing the composite cover plate 210 at the positive terminal of the battery cell 100 is similar to that at the negative terminal and will not be described again. During the process, the composite cover plate 210 can be installed at either the positive or negative terminal of the battery cell 100 first, and then another composite cover plate 210 can be installed at the other end; alternatively, the composite cover plates 210 can be installed simultaneously at both ends of the battery cell 100.

[0081] Specifically, the connection between the flexible connecting piece 400 and the current collector welding end 111, as well as the connection between the flexible connecting piece 400 and the composite cover plate 210, are all achieved by laser welding, which reduces welding deformation, increases welding speed, and improves welding effect.

[0082] The method for preparing a soft-pack battery provided in this embodiment of the invention involves bending the current collector of the cell 100 by 90° before welding, which avoids the waste of welding space caused by the straight tabs during conventional soft-pack battery packaging, and can significantly improve the energy density of the battery. The electrode of the cell 100 is welded to the composite cover plate 210, and the current is conducted by the electrode post 213 on the composite cover plate 210, thereby improving the current carrying capacity of the battery.

[0083] In an optional embodiment, step S30, sealing the tab 212 and the soft packaging material by hot pressing, specifically includes: using aligned cylindrical heads or segmented heads to perform rolling hot pressing encapsulation of the tab 212 and the soft packaging material.

[0084] Figure 5 This is a schematic diagram of the structure of a pouch battery after the tabs are packaged, according to an embodiment of the present invention. In one embodiment, as shown... Figure 5 As shown, both the inner end cap 502 and the outer end cap 501 are cylindrical end caps, with the tab 212 and the flexible packaging material located between the two cylindrical end caps. During the forward movement of the tab 212 and the flexible packaging material, the two cylindrical end caps heat-seal the edges of the tab 212 and the flexible packaging material. Because the forward movement of the tab 212 and the flexible packaging material is continuous and uninterrupted, this rolling heat-sealing method is also called continuous sealing. This sealing method greatly improves production efficiency and prevents misalignment of the tab 212 and the flexible packaging material. Using aligned cylindrical end caps for sealing reduces the contact area, allowing for heat-sealing under lower pressure. Alternatively, both the inner end cap 502 and the outer end cap 501 can be segmented end caps to prevent the PP layer from being pushed outwards, causing fusion failure and reducing sealing abnormalities that occur during normal heat sealing.

[0085] In another optional embodiment, step S30, sealing the tab 212 and the soft packaging material by hot pressing, specifically includes: splicing and encapsulating the tab 212 and the soft packaging material using inner and outer straight end caps or inner and outer arc end caps.

[0086] Specifically, the tab 212 and the flexible packaging material are conveyed forward. When they reach the heating position, the inner end cap 502 and the outer end cap 501 simultaneously move to opposite sides of the tab 212 and the flexible packaging material and heat-seal them. After the inner end cap 502 and the outer end cap 501 leave the surface of the tab 212 and the flexible packaging material, the tab 212 and the flexible packaging material continue to move forward, causing the next packaging section to move to the heating position. The inner end cap 502 and the outer end cap 501 then move to opposite sides of the tab 212 and the flexible packaging material again and heat-seal them. This cycle repeats, and the various packaging sections are spliced ​​together to form a continuous packaging area until the entire area to be packaged is intermittently packaged. Optionally, both the inner end cap 502 and the outer end cap 501 are cylindrical end caps or straight end caps.

[0087] Based on any of the above embodiments, step S30, after sealing the tab 212 to the soft packaging material by hot pressing, further includes:

[0088] Step S40: Perform top sealing operations on the positive and negative sides of the cell 100 respectively, and seal the positive and negative terminals of the air bag 301 respectively.

[0089] Step S50: Inject electrolyte into cell 100, and seal the side of gas bag 301 after the electrolyte injection is completed; perform formation treatment on cell 100, and perform exhaust and resealing after the formation of cell 100 is completed.

[0090] Specifically, after hot pressing to seal the tab 212 and the soft-pack material, top sealing operations are performed on the positive and negative sides of the cell 100 respectively. Figure 6 This is a schematic diagram of the structure of the soft-pack battery provided in an embodiment of the present invention after top sealing. Figure 6 As shown, a positive top seal edge 321 is formed on the positive electrode side of the battery cell 100, and a negative top seal edge 322 is formed on the negative electrode side. Then, the positive and negative terminals of the gas bag 301 are sealed, forming a positive gas bag seal edge 331 and a negative gas bag seal edge 332, respectively. The positive terminal of the gas bag 301 is the end of the gas bag 301 on the same side as the positive electrode side of the battery cell 100, and the negative terminal of the gas bag 301 is the end on the same side as the negative electrode side of the battery cell 100. After the top sealing operation and the sealing operations of the positive and negative terminals of the gas bag 301, only the side of the gas bag 301 away from the battery cell 100 remains open, through which electrolyte is injected into the battery cell 100. After the electrolyte injection is completed, the sidewall of the gas bag 301 is sealed, completely isolating the inside of the battery cell 100 from the external environment. Then, the cell 100 is allowed to stand, with high-temperature or room-temperature standing depending on the manufacturing process, to ensure that the injected electrolyte fully wets the electrode plates. After standing, the cell 100 undergoes formation treatment.

[0091] During the formation process, the battery cell 100 undergoes its first charge. The electrode material and electrolyte react at the solid-liquid interface, forming a passivation layer covering the electrode material surface. This passivation layer exhibits the characteristics of a solid electrolyte and is called a solid electrolyte interface (SEI) film. The SEI film is insoluble in organic solvents and can exist stably in organic electrolyte solutions. Solvent molecules can pass through this passivation layer, effectively preventing the co-intercalation of solvent molecules and avoiding damage to the electrode material caused by solvent molecule co-intercalation. This significantly improves the cycle performance and lifespan of the electrode. Since the battery cell 100 may deform after formation, a shaping process can be added after formation.

[0092] It should be noted that after pre-sealing and top sealing are completed, the sealing quality needs to be checked with a testing device to prevent defective products from flowing to the next stage.

[0093] Since gas is generated during the formation process, it needs to be extracted before the second sealing. Specifically, the gas bag 301 is punctured using a guillotine or similar tool, and a vacuum is simultaneously drawn to expel the gas from the gas bag 301. Then, the gas bag 301 is sealed on the side closest to the battery cell 100. Figure 7 This is a schematic diagram of the structure of the soft-pack battery provided in an embodiment of the present invention after vacuuming and double-sealing. Figure 7 As shown, after the gas bag 301 is sealed twice, a vacuum-sealed edge 340 is formed, completing the encapsulation of the entire battery cell. The second sealing operation is performed immediately after the gas is extracted to ensure the airtightness of the battery cell 100. Optionally, a segmented vacuuming method can be used during the vacuuming process. The gas bag 301 is divided into several segments, and the vacuum is slowly evacuated to the set vacuum level. Compared with the method of evacuating all the way through, the vacuuming speed is reduced, avoiding the extraction of too much electrolyte and reducing the defect rate of the battery cell 100 in the vacuum-sealing stage. After the second sealing is completed, the gas bag 301 is cut off. Figure 8 This is a schematic diagram of the soft-pack battery structure after folding, as provided in an embodiment of the present invention. The vacuum-sealed edge 340 is folded, as shown... Figure 8 As shown, after folding, a sealing fold 341 is formed. This sealing fold 341 is close to the battery cell 100 to ensure that the width of the battery cell 100 does not exceed the standard.

[0094] After being folded, the battery cell 100 undergoes capacity grading in a capacity grading cabinet to test whether its capacity reaches the specified minimum value. After the capacity grading test, any cells 100 that fail the capacity test are discarded to prevent them from entering the next stage. Cells 100 that pass the capacity test will proceed to subsequent processes, such as appearance inspection, application of adhesive tape, and edge voltage testing. The specific steps may be added or removed depending on the manufacturing requirements of the pouch battery.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite cover plate, characterized in that, The device includes a cover plate body and electrode tabs. The electrode tabs are arranged circumferentially around the cover plate body. The outer edge of the electrode tabs has a folded edge perpendicular to the cover plate body. The folded edge is used for sealing connection with soft packaging material. The cover plate body is provided with a pole post, which is used to connect to the electrode terminals of the battery cell.

2. The composite cover plate according to claim 1, characterized in that, The electrode tab and the cover plate body are an integral structure.

3. The composite cover plate according to claim 1, characterized in that, The electrode tab is welded and fixed to the cover plate body.

4. The composite cover plate according to claim 1, characterized in that, The pole and the cover plate are an integral structure.

5. The composite cover plate according to claim 1, characterized in that, The cover plate body is provided with pole hole, and the pole is installed in the pole hole.

6. The composite cover plate according to claim 5, characterized in that, The electrode has two terminals, one of which is the positive terminal and the other is the negative terminal.

7. The composite cover plate according to claim 1, characterized in that, The outer side of the folded edge is provided with tab adhesive.

8. The composite cover plate according to claim 7, characterized in that, The inner side of the folded edge is provided with the tab adhesive.

9. The composite cover plate according to claim 1, characterized in that, The electrode lug includes a base plate and a connecting edge. The base plate is parallel to the main body of the cover plate. The folded edge and the connecting edge are perpendicularly arranged on opposite sides of the base plate. The connecting edge is connected to the main body of the cover plate.

10. A pouch battery, characterized in that, It includes a battery cell and a composite cover plate as described in any one of claims 1 to 9, wherein the positive and negative terminals of the battery cell are respectively connected to the terminals of the composite cover plate.

11. A method for preparing a soft-pack battery as described in claim 10, characterized in that, include: The positive and negative terminals of the battery cell are welded and fixed to the terminals of the composite cover plate, respectively. The battery cell and the composite cover plate are covered with a soft-pack material, with an air pocket provided. The soft-pack material is pre-sealed at both ends near the battery cell; The tabs are sealed to the soft packaging material by hot pressing.

12. The preparation method according to claim 11, characterized in that, The specific steps of welding and fixing the positive and negative terminals of the battery cell to the terminals of the composite cover plate include: The current collector of the battery cell is bent at 90°, and the bent current collector is welded and fixed to the flexible connecting piece. Then the flexible connecting piece is welded and fixed to the pole of the composite cover plate.

13. The preparation method according to claim 11, characterized in that, The process of sealing the tab to the soft packaging material by hot pressing specifically includes: The tabs and the soft-pack material are rolled and heat-pressed together using aligned cylindrical or segmented end caps. Alternatively, inner and outer straight end caps or inner and outer circular arc end caps can be used to splice and encapsulate the electrode tabs and the soft packaging material.

14. The preparation method according to any one of claims 11 to 13, characterized in that, After sealing the electrode tab to the soft packaging material by hot pressing, the process further includes: Top sealing operations are performed on the positive and negative sides of the battery cell, and the positive and negative terminals of the air bag are sealed respectively. Electrolyte is injected into the battery cell, and the side of the gas bag is sealed after the injection is completed; the battery cell is subjected to formation treatment, and after the formation of the battery cell is completed, the gas is vented and sealed again.

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